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History of Control

Contributed by Ljubo Vlacic.

Control Systems Timeline

A modern view of control systems is one of using feedback to control a system regardless of any external disturbances. It is this durability that explains why control systems are all around us in modern technology. Control Systems have widespread applications in a number of different fields however they are barely noticed, but without them many of today’s technological advancements would not be possible. They are found in our homes, cars, factories, communication, medical services, transport, military, and space systems to name a few. The evolution of the control system is a long and interesting one, dating back to around 300 B.C. From then on control systems have played an essential part in the development of wide variety of technology.

"One interesting aspect in the history of technology is the way in which an innovation was developed. In many cases, inventions were the result of numerous people making small advances until a critical point was reached". (Bernstein and Bushnell 2002 p22) ([38]). There are many examples of this throughout the history of control with inventions being improved and adapted for different tasks. A couple of these examples are listed below:

  • The centrifugal governor began in the works of windmills, but found itself in the control of steam engines.
  • Leon Foucault first described the gyrocompass in 1852, but it wasn’t until 1908 that H. Anschutz-Kampfe developed the first practical gyroscopic compass based on Foucault’s work. A couple of years later Elmer A. Sperry developed a gyrocompass that was an improvement over the Anschutz design. Between work on the gyrocompass, Sperry created his gyroscope for the stabilization and steering of ships, which was also later used in aircraft. This gradual advance marked the beginning of the modern day autopilots and navigation systems.

The examples above show that even though one person is credited with the invention, it is usually the result and effort of many before them. As you read through the following, and further enlighten your study on control systems engineering, you will become aware of the wide variety of applications and the opportunities that are presented by the use of control systems.

270 B.C
  • Water clock invented by a Greek mechanician named Ktesibios. ([3] p112)([4] p4)

  • 250 B.C
  • Philon of Byzantium used a float regulator to control the level of oil in a lamp. (Similar to the idea of liquid-level control used by Ktesibios). ([4] p4)

  • 1st Century A.D
  • Heron of Alexandria used the float valve principle to describe several devices in his book Pneumatica, including a wine dispenser and floating siphon. ([3], [11])

  • 10th Century
  • Archimedes of Syracuse designed a water clock using float valves, with features such as adjustable day length and hourly events. ([11] p28-31)

  • 12th Century
  • The south-pointing chariot and the drinking straw regulator invented in China. ([6], [11] p49-51)

  • 14th Century
  • The mechanical clock was invented sometime during the 14th century the true inventor however is not known. [6]

  • 1620
  • Cornelis Drebbel constructed the first underwater vessel, the submarine. ([36])

  • Thermostat invented by Cornelis Drebbel. ([2] p9) ([3] p114)

  • Other temperature regulators invented probably depending on Drebbel’s work are:
    1680   Johann Joachim Becher
    1747-1757   Antoine Ferchault Réaumur
    1771   William Henry’s "Sentinel Register" ([11])
    1783   Bonnemain

  • 1674
  • Hooke designed a mechanism for rotating a telescope at constant speed. ([1] p58)

  • 1681
  • Safety Valve (pressure regulator) invented by Denis Papin. ([4] p5) ([5] p3) ([6])

  • 1707
  • Papin used his safety valve as a regulating device on a steam engine. ([6] [11])

  • 1717/1718
  • The safety valve becomes a standard accessory of steam engines and can be found on practically every steam engine. ([11] p82)

  • 1745
  • Fantail, device for the automatic control of windmills, invented by Edmund Lee. ([3] p115) ([5] p3)

  • 1758
  • James Brindley was the first to use the float valve regulator in a steam boiler. ([11] p 77)

  • 1765
  • In Russia, Ivan Ivanovich Polzunov developed a water float regulator for a steam engine. ([6]) ([7] p4) ([11] p77-79)

  • 1775
  • Float regulator was used in the first patents for the flush toilet. ([6] [11] p76)

  • 1776
  • David Bushnell invented a hand-powered submarine called the Turtle. ([36])

  • 1784
  • Float valve regulators continued to advance with Sutton Thomas Wood using one for a steam engine in his brewery. ([6] [11] p78)

  • 1785
  • Robert Hilton took out the first patent for the lift tenter. ([11] p99)

  • 1787
  • Thomas Mead invented the practical lift tenter. ([1] p10) ([3] p116)

  • 1788
  • Centrifugal flyball governor for regulating the speed of a steam engine invented by James Watt. ([5] p4, [11] p2)

  • 1790
  • The brothers Périer of France came up with a float regulator to control the speed of a steam engine, but it was inferior to the Watt centrifugal governor, therefore not nearly as successful. ([6], [11] p115-118)

  • 1793
  • Abraham Louis Breguet invented a closed-loop feedback system to synchronize pocket watches. ([6], [11] p119)

  • 1799
  • Papin’s pressure regulator was further improved by Robert Delap then Matthew Murray. ([6], [11] p85-87)

  • 1803
  • Matthew Boulton and James Watt combined a pressure regulator with a float regulator for use in their steam engines. ([6])

  • 1809
  • Sir Humphrey Davy demonstrated the arc lamp. ([1] p153) ([42])

  • 1822
  • Mark Brunel devised a spring-loaded governor for marine steam engines. More practical versions were later developed, including that of John Bourne (1834), Thomas Silver (1855) and Thomas R. Pickering (1862). ([1] pp28,35) ([5] pp18,28)

  • 1824
  • Joseph Von Fraunhofer constructed a large telescope at Dorpat. It’s constant rotation (synchronous with that of the earth), was driven by clockwork and regulated by a friction governor. ([1] p58)

  • 1840
  • George Biddell Airy built a feedback device for a telescope to compensate for the earth’s rotation. ([6]) ([1] p57)

  • 1848
  • George Henry Corliss built the first successful automatic release cut-off control for the valve gear of a steam engine, resulting in greatly improved engine efficiency. ([5]) p8-9).

  • W. Edward Staite and Leon Foucault simultaneously solved the problem of automatically controlling the arc length in the arc lamp. ([5] p105)

  • 1851
  • H.A. Luttgens patents his steam engine speed regulator incorporating integral control for greatly improved accuracy. ([5] p16-17)

  • 1852
  • Leon Foucault described the gyroscopic compass. ([5] p101)

  • 1857
  • The first passenger elevator, invented by Elisha Otis, was installed at 488 Broadway in New York City. ([13], [43])

  • D.W. Snell and S.S. Bartlett invent and patent their “Bartlett Let-Off” mechanism for controlling and maintaining constant tension in yarn on power looms. It was implemented in the “Model A Northrop” power loom (1895) which was also famous for its automatic shuttle-bobbin changer. Similarly designed machines were also invented by Richard Walker (1867) and George Richardson (1867). ([5] p79-82)

  • H.N. Throop greatly improved the response of the marine-engine governor, designing a spring-loaded governor with proportional-plus-derivative response. ([1] pp27-29) ([5] p19)

  • 1858
  • Porter designed a loaded governor for high speed operation. The design was implemented in the Porter-Allen high speed steam engine (1881), leading to his reputation as the “father of the high speed engine”. ([1] pp29-34) ([5] pp13-15)

  • 1864
  • The first submarine, the Hunley, to sink an enemy ship in combat. ([36])

  • 1866
  • J. McFarlane Gray patents first steam powered ship steering engine incorporating feedback. ([1] pp98-100)

  • 1867
  • Robert Whitehead demonstrated the first self-propelled torpedo. ([1] p119)

  • 1868
  • J.C. Maxwell analysed the stability of Watt's flyball governor. ([2] p12)

  • Jean Joseph Léon Farcot patents his “servomechanism” for the steering of steam engines. ([1] p101)

  • 1870-84
  • Commander John Adams Howell worked on and developed the Howell torpedo. ([1] p121, [5] p100)

  • 1877
  • Edward J. Routh developed the Routh criterion for determining stability, known today as the Routh-Hurwitz criterion. Adolf Hurwitz also did this independently in 1895. ([6], [24])

  • I.I. Vishnegradsky analysed the stability of dynamic systems using differential equations independently of Maxwell. ([6], [24])

  • 1884
  • Charles A. Parsons invents the first practical steam turbine aimed at powering ships. ([5] p45-47) ([50])

  • 1885
  • First point in history that remote-controlled naval vessels appear. ([23])

  • 1887
  • Chichester Bell and Charles Tainter improved on Edison’s Phonograph (1877) with the Bell & Tainter Graphaphone. ([5] p65-68)

  • 1891
  • H Ward Leonard motor-generator system for speed control ([1] p.172)

  • 1892
  • A.M. Lyapunov studied the stability of non-linear differential equations. ([6])

  • 1892-1898
  • Over this period Oliver Heaviside contributed to the mathematical analysis of control systems, and is considered to be the inventor of operational calculus. ([6])

  • 1893
  • Aurel Boleslaw Stodola was the first to introduce the idea of the system time constant, while studying the dynamics involved in the regulation of a water turbine. In 1895 Stodola approached Adolf Hurwitz with the problem of determining the stability of the characteristic equation. Hurwitz solved the problem unaware of the work of Maxwell and Routh. ([6])

  • 1895
  • As an improvement to the torpedo, Ludwig Obry invented a gyroscopic device that was used for the directional control of the torpedo. ([1] p122, [5] p99)

  • 1898
  • Nikola Tesla built his propeller-driven radio controlled boat, considered the birth of all remotely operated vehicles. ([46])

  • 1902
  • Tirrill electric voltage regulator ([1] p.167)

  • 1903
  • (17 December) The Wright brothers demonstrate the first truly controlled, sustained, powered, and heavier than air flight. ([44])

  • 1908
  • H. Anschutz-Kampfe developed the first practical gyroscopic compass that was successfully tested in 1908 and widely used in navigation thereafter. ([5] p101)

  • 1909-1911
  • Elmer Ambrose Sperry developed his gyrocompass, which was an improvement over the Anschutz designed compass. ([5] p101, [54])

  • 1910
  • Elmer A. Sperry invented a gyroscope for use in the stabilization and control of ships. ([6], [1] p125)

  • 1912
  • Elmer A. Sperry began work on the Sperry gyropilot, an automatic steering system for ships. ([1] p130 and [5] p102)
  • Edwin Howard Armstrong invented a triode-based amplifier circuit that used positive feedback. ([10])

  • 1913
  • Henry Ford introduces a mechanized assembly line for automobile production ([21])

  • 1914-18
  • The Germans built 17 FL-7’s, electronically controlled motorboats, for coastal defence. ([23])

  • The U-boats of Germany demonstrated the effectiveness of the submarine in combat during World War I. ([36])

  • 1914
  • Lawrence Sperry demonstrated the displacement gyroscope (airplane autopilot) for planes that had been developed by his father Elmer Sperry. ([10] p63)
  • First automatic electricity sub-station. ([41] p262)
  • E.H. Bristol (Foxboro Company) patent for pneumatic flapper mechanism filed (granted 1922 no. 1,405,181) ([26] p31)

  • 1918
  • E. E. Wichersham designed and developed a demolitions carrier called the Land Torpedo. ([23])

  • The first successful flight of an unmanned and not radio controlled aircraft. ([23])

  • 1920s and 1930s
  • These years saw the boom of communication systems, and at the forefront were Bell Telephone Laboratories who were applying the frequency domain techniques of Laplace, Fourier, Cauchy, and others. ([6])

  • Early 1920s
  • The U.S. Naval Research Laboratory built a remote-controlled ground vehicle, the Electric Dog. ([23])

  • 1922
  • Nicholas Minorsky presented a clear theoretical analysis for the automatic steering of ships; he also developed a three-term controller, thereby becoming the first to use the proportional-integral-derivative (PID) controller. ([6], [24])

  • 1927
  • Harold Stephen Black invented the negative feedback amplifier in order to reduce distortion in repeater amplifiers used in telephone systems. ([6], [10], [24], [25], [45])

  • 1930
  • J Pestarini - Metadyne
  • Photoelectric cell begins to be widely used in industry as a control device. ([26] p21)

  • 1931
  • Foxboro Company Stabilog designed by Clesson E Mason. This controller provided proportional plus integral action control. ([26] p40)
  • MIT Differential Analyzer which incorporated high performance servomechanisms ([26] p103)

  • 1932
  • Harry Nyquist developed his regeneration theory as a result of investigating the conditions for which a feedback amplifier is stable. From this he derived his Nyquist stability criterion. ([6], [10], [24], [26])

  • 1933
  • The first time an unmanned aircraft, the Fairy Queen, is used as a target drone for gunfire practice. ([48])

  • 1934
  • Harold Locke Hazen papers on Theory of servomechanisms and design of a high speed servomechanism. ([26] p106)

  • 1935
  • British physicist Sir Robert Watson-Watt produced the first practical radar. ([32])

  • 1936
  • George A. Philbrick started work on an electronic analyser for control problems. ([5] p125)
  • A Callender, D R Hartree & A Porter use of a process simulator for analysis and simulation of the effects of time lag in a control system ([26] p55)

  • 1938
  • Hendrik Wade Bode was able to investigate stability using the magnitude and phase frequency response plots of a complex function, known today as Bode plots, he also introduced the notions of gain and phase margin. ([6], [26])

  • 1939
  • The Borgward Company in Bremen, Germany began the development of the B1V Demolition Vehicle, the first operational remote-controlled land vehicle. ([23])
  • Taylor Company Fulscope - a pneumatic controller with pre-PID control action. ([26] p49)
  • Foxboro Model 30 Stabilog - a pneumatic controller with PID control but only P and I were adjustable, changes in P and I resulted in automatic changes in setting of D term. Control action referred to as "Hyper-Reset" ([26] p49)

  • 1940
  • The British firm W. H. Allen & Company, with A. C. Hutchinson and F. S. Smith, designed the first military related walking machine. ([23])

  • David B. Parkinson (Bell Telephone Laboratories) designs anti-aircraft gun controller, with production starting early 1943. ([7] p8, [26] p126,171)

  • 1941
  • Albert C. Hall recognized the harmful effects of ignoring noise in control system design, while designing an airborne radar ([6], [26])

  • 1942
  • (October 3) The beginning of the modern day missile with the launch of the first V-2 (originally called A-4) missile by Wernher von Braun and Walter Dornberger ([29])
  • Rules for tuning PID controllers J G Ziegler & N B Nichols ([26] p60)
  • F. C. Williams invents the Velodyne a d.c. motor with an integral tachogenerator used initially in auto-tracking radar systems. ([26] p147)

  • 1943
  • (August 27) The first successful guided missile attack. ([46])
  • George R Stibitz relay controlled servo-system (sampled data system) ([26] p156)

  • 1944
  • (June 12) The German Fiesler 103, or the “V-1 Buzz Bomb”, was the first unmanned aircraft to be used in combat. ([48], [23])
  • Inverse Nyquist technique (developed independently by A. L. Whiteley in England and by H T Marcy and H Harris Jr in USA
  • ([26] p148)

  • 1945
  • Cruise control invented by Ralph Teetor. ([8])

  • 1947
  • Nathaniel B. Nichols developed his Nichols Chart. ([6], [26])

  • 1948
  • Walter R. Evans developed the root locus technique. ([4] p6, [28])

  • 1950s
  • During this time most of the work in control was associated with the s-plane and on obtaining desired closed-loop characteristics. ([6])

  • 1950
  • The Sperry Rand Corporation built UNIVAC I, the first commercial data processing machine. ([6])
  • John Hopps invented the world's first cardiac pacemaker. His device was far too large to be implanted inside of the human body, and therefore it was an external pacemaker. ([33])

  • 1951
  • The Ryan Aeronautical Company produced the first jet-engine target drone, the Firebee.
  • First commercial digital computers run Ferranti Mk in the UK in February and a little later the Sperry Univac in the USA. Followed in September 1951 by LEO 1 based on the Cambridge EDVAC design. The LEO—Lyons Electronic Office—was built for the Lyons Catering Company. ([53])

  • 1956
  • Lev Pontryagin developed his maximum principle theory. ([47])

  • Digital computers first used to control processes. The Port Arthur Refinery began development in 1956, going online with the computer controlled system in 1959. ([51] p3)

  • 1957
  • October 4, the Russians launch the first artificial satellite, Sputnik. ([17])

  • R. Bellman contributed to control theory with his dynamic programming technique. ([6] [47])

  • A New Jersey based company called Vare built a mobile underwater T.V. system and recharged the concept of using unmanned naval vessels. ([23])

  • (October) Soviet Union begins the first tests of Intercontinental Ballistic Missiles. ([37])

  • (December 17) U.S. tests its first Intercontinental Ballistic Missile. ([37])

  • 1957-1958
  • U.S. starts developing the first Anti-Ballistic Missile system to defend against incoming missiles. ([37])

  • 1958-1960
  • The implantable pacemaker was invented from 1958 through 1960 by William Chardack, Andrew Gage, and Wilson Greatbatch.([33])

  • 1958-1974
  • The U.S. Navy funded 8 more versions of this type of remotely operated vehicles, 3 of them being modifications of the original CURV. The purpose of these vessels was not military, but rather to inspect, retrieve and rescue. ([23])

  • 1958
  • The development of the cable-controlled underwater recovery vehicle (CURV) began at the U.S. Naval Ocean Systems Centre. ([23])

  • 1959
  • (March 13) The first reported use of a digital computer, the Ramo-Wooldridge RW-300, in a closed-loop process control. ([5] p 126)
  • Work begins on a digital computer for fully direct control of a process. ([53])

  • Late 1950s & 1960s
  • The U.S. Army developed several legged vehicles including the Quadroped and the ASV (Adaptive Suspension Vehicle). ([23])

  • 1960
  • Charles S. Draper developed and invented his inertial navigation system. ([6])

  • Rudolph E. Kalman published his famous paper on optimal filtering and estimation, describing the Kalman filter. ([6] [47])

  • 1961
  • George Devol and Joseph Engelberger invented the first industrial robot, Unimate. ([14])

  • (March 4) The Soviet Union carries out a successful Anti-Ballistic Missile demonstration by intercepting a ballistic missile. ([37])

  • April 12, Yuri Alexeyevich Gagarin was the first man in space on board the spaceship Vostok 1. ([20])

  • 1962
  • (March 19) The U.S. begins tests of its Anti-Ballistic Missile system. ([37])

  • 1963
  • The first reconnaissance flight performed by an unmanned aircraft. ([23])

  • The Applied Physics Laboratory of the University Of Washington began the development of the SPUR (Self-Propelled Underwater Research Vehicle). ([23])

  • 1969
  • First microprocessor invented by Ted Hoff. ([2],[12], [16]),

  • Mid 1970s
  • Cable controlled remotely operated sea vehicles were used as mine-destruction devices. ([23])

  • 1976
  • First Space Shuttle ([19])

  • 1981
  • Columbia becomes the first Space Shuttle to fly into Earth orbit ([18])

  • The first of the U.S. Navy’s ballistic missile submarines was commissioned, having the capability of carrying twenty-four nuclear missiles and being practically undetectable. ([36])

  • 1997
  • (July 4) First ever autonomous rover, Sojourner, explores Mars. Sojourner was designed by a large NASA team lead by Jacob Matijevic and Donna Shirley. ([15][7])

  • Control Systems Timeline Details

    270 B.C
  • Water clock invented by a Greek mechanician named Ktesibios. ([3] p112)([4] p4)

    The water clock, invented by the Greek mechanism Ktesibios, is the earliest known control device to be constructed. The device worked by way of a slow trickle of water, flowing at a constant rate, into a measuring container, where an indicator in the measuring container would then tell the time as the water level rises. In order for the device to be successful the supply tank had to be at a constant level so the water would flow into the measuring container at a constant rate. To do this Ktesbios used a float regulator, similar to the device used in today’s flush toilet. When the water in the supply tank is at the right level, the float only allows enough water into the timekeeping tank for the system to operate correctly. If the water level in the supply tank falls below or rises above the desired level, the float opens or closes the water supply until the water level returns to the desired level. From this description you can deduce that the water clock uses feedback to keep the supply tank at a constant level, therefore making it also the first device to incorporate feedback.

  • 250 B.C
  • Philon of Byzantium used a float regulator to control the level of oil in a lamp. (Similar to the idea of liquid-level control used by Ktesibios). ([4] p4)

    Using a similar principle of liquid-level control as Ktesibios, Philon of Byzantium was able to apply it to an oil lamp. He used a float regulator to keep a constant level of oil in the lamp. The idea of the float regulator was to replenish the oil as it burned, keeping the level constant. The lamp was made up of two containers filled with oil, sitting on top of each other. The lower container, which was open at the top, contained the fuel for the lamp, while the upper closed container held the reserve fuel that would be transferred to the lower container as the oil burned. Two capillary tubes and another tube, called a vertical riser, connected the containers. The vertical riser was inserted just below the surface of the oil in the lower container. As the oil burned, it was exposed to air, forcing oil to flow from the upper container through the capillary tubes into the fuel supply below. This continued until the fuel supply returned to its previous level and the vertical riser was no longer exposed to the air. In this way the lamp’s fuel supply was maintained by keeping a constant level of oil in the lower container.

  • 1st Century A.D
  • Heron of Alexandria used the float valve principle to describe several devices in his book Pneumatica, including a wine dispenser and floating siphon. ([3], [11])

    Heron wrote about several devices that use the float valve principle based on the work of Ktesibios, however they use a considerably more sophisticated technique than that of Ktesibios. In fact Heron showed that in a feedback control device the control element and the sensing element do not have to be connected to each other and can be separated. A good example of this was his ‘wine dispenser’ where the valve, the control element, is not directly attached to the float, the sensing element, with the system still able to keep a constant level of wine. Another of Heron’s creations is the floating siphon. The system consists of a siphon connecting two vessels that have different amounts of liquid levels. The siphon sits on the lower of the two and is attached to a small overflow vessel. The system operates by having liquid flow at a constant rate from the higher vessel to the lower vessel until a preset difference level has been reached. The system regulates the difference between the two with respect to the lower vessel. The distance between the level of the overflow and the bottom of the float is the liquid level difference between the two vessels. The system compensates for any disturbances such as the addition of liquid to the upper vessel or the removal of liquid from the lower vessel. As can be seen from these two descriptions the devices of Heron used the same float valve principles as those before him.

  • 10th Century
  • Archimedes of Syracuse designed a water clock using float valves, with features such as adjustable day length and hourly events. ([11] p28 - 31)

    Archimedes water clock was of a more complicated design, while still using float regulation for control. The clock was driven by a large float on a steadily dropping water reservoir. The rate at which the water flowed from this reservoir was kept constant using a float valve regulator. Flow of water then activated the special events at particular intervals (such as a number of marbles rolling from a bird’s mouth, etc). His design was published by an unknown third party in a work entitled “Work of Archimedes on the Building of Clocks”, and was found to influence many other works for some time thereafter.

  • 12th Century
  • The south-pointing chariot and the drinking straw regulator invented in China. ([6], [11] p49-51)

    The south-pointing chariot is a normal two-wheeled chariot with a small human statue attached to the front. The statue is turned by a gearing mechanism attached to the wheels of the chariot so that it continuously points south, regardless of the direction of the chariot. Thus the driver is able to determine in which direction they are going and easily follow a straight course without depending on any external help from landmarks for instance. The south-pointing chariot is only considered a feedback device if the driver is considered as part of the system, since it is the driver that does the comparing and the compensating.

    The purpose of the drinking straw regulator was to regulate the wine consumption of the participants in a drinking bout. The wine is drunk through a bamboo tube that has a movable stopper inside it. The purpose of the stopper is to limit the rate of flow. If one sucks too slowly or too quickly the holes will be automatically closed, therefore the objective is to try to keep a constant rate in between the two extremes.

  • 1620
  • Thermostat invented by Cornelis Drebbel. ([2] p9) ([3] p114)

    Cornelis Drebbel, a Dutch engineer who migrated to England, originally devised the thermostat to serve another purpose. Believing it was possible to transform base metals to gold if the temperature of the process was kept constant was the original motivation behind Drebbel’s temperature regulator. The set-up consisted of a box that contained the fire, with a ventilation shaft at the top fitted with a damper. Inside was the double-walled incubator box that had water between the walls to ensure even distribution of heat. The temperature sensor is a glass vessel located between the walls in the water and filled with alcohol and mercury. As the temperature in the box increases, the increased pressure of the heated alcohol pushes up the mercury, which in turn pushes up a rod that lowers and closes the damper. If the temperature is too cold, the pressure is reduced, the mercury drops lowering the rod and therefore opening the damper allowing the fire to burn hotter. The length of the rod is used to set the temperature of the incubator.

  • 1674
  • Hooke designed a mechanism for rotating a telescope at constant speed. ([1] p58)

    Hooke described a mechanism for rotating a telescope at constant speed, turning it synchronously with the earth’s rotation. This was the first description of such a device, though never implemented. His design used a centrifugal pendulum, with air resistance providing the force for resistance of overspeed.

  • 1681
  • Safety Valve (pressure regulator) invented by Denis Papin. ([4] p5) ([5] p3) ([6])

    Denis Papin invented the safety valve in 1681 as a pressure regulator for his pressure cooker. The valve top was weighted in order to set the pressure of the boiler to the desired level. The valve was used to compare the actual pressure (inside the boiler) with the desired pressure (the weight). If the upward pressure of the boiler exceeded the weight, the valve would open and steam would be released until equilibrium is reached. If the actual pressure did not exceed the weight, the valve did not open and the pressure inside the boiler would continue to increase. Therefore the weight on top of the valve set the internal pressure of the boiler. Although the safety valve was originally intended as a pressure regulator for a pressure cooker, it became a standard accessory for steam boilers within a few decades.

  • 1745
  • Fantail, device for the automatic control of windmills, invented by Edmund Lee. ([3] p115) ([5] p3)

    One of the groups that had a major influence upon 18th century technology was the English and Scottish millwrights. Patented by Edmund Lee in 1745 was the first of the millwright’s devices, the fantail. The fantail is designed to automatically keep a windmill facing the wind. It is a small auxiliary wind-wheel mounted at right angles to the main wheel and attached to the rear side of a windmill's moveable cap. The fantail, through a series of gears, controlled the turning of the cap. Therefore any rotation of the fantail would cause the cap and thus the main wheel to turn. When the main wheel faced the wind, the fantail (at right angles to the main wheel) is parallel to the wind and does not rotate. If the wind direction changes so the main wheel is no longer directly facing it, the wind will cause the fantail to rotate which in turn slowly turns the cap until the fantail becomes parallel to the wind again and the main wheel directly faces it. Thus the system would automatically turn the windmill to keep it directly facing the wind. The windmill also contained an invention that controlled its speed in spite of changes in the wind velocity. This was achieved by allowing the windmill blades to pivot around the arms that held them. The blades were connected to a counterweight that, in increasing winds, if the force was greater than that of the counterweight, pitched the blades farther back, so that less area was available. As the winds decreased to be less than that of the counterweight, more blade area was made available.

  • 1758
  • James Brindley was the first to use the float valve regulator in a steam boiler. ([11] p 77)

    James Brindley used the float valve in a steam boiler for regulating the level of the water. The float controls the feed valve, which in turn controls the input of water. The system works automatically, replenishing the lost water, but the whole arrangement is similar to the float regulators used by Heron around 1700 years earlier.

  • 1765
  • In Russia, Ivan Ivanovich Polzunov independently developed a water float regulator for a steam engine. ([6], [7] p 4, [11] p 77-79)

    The steam engine was designed to drive fans for the blast furnaces in a coal mine. Polzunov’s water float regulator was used to control the amount of water flowing into the boiler of the engine. Similar to previous designs, as the water level changed, movement of the float would result in a compensating change in the opening of the water intake valve. This design is considered to be developed independently of previous models due it its somewhat different implementation of the float regulator.

  • 1785
  • Robert Hilton took out the first patent for the lift tenter. ([11] p99)

    This was the first solution proposed to the problem that the millstones move apart as the speed of the windmill increases. The device also has, to a certain extent, the effect of regulating the speed of the windmill. Speed regulation is not the intention of the device; its sole purpose was to regulate the gap between the millstones to produce a uniform quality of flour. The speed regulation occurs when the speed increases and the stones are pushed together with a greater force, the friction between the stones therefore increases and the motion of the mill is consequently slowed down. The speed sensing method obtained may have been adequate for the time, but there would soon be a far superior method in the centrifugal pendulum that would render it insignificant.

  • 1787
  • Thomas Mead invented the practical lift tenter. ([1] p10) ([3] p116)

    The lift tenter designed in 1787 by Thomas Mead as a means to counteract the tendency of millstones to move apart as the speed of rotation of a windmill increased was far superior to that of Robert Hilton two years earlier. The idea of the lift tenter was to press the millstones together with a force proportional to the speed of the windmill. To produce a true feedback speed sensing system, Mead combined the lift tenter idea with the use of the centrifugal pendulum. The pendulum measured the speed of the millstones rotation and via mechanical connections, adjusted the area of the sails of the windmill to keep the speed of the wheel constant. Therefore the system kept the millstones the desired distance apart by keeping the speed constant.

  • 1788
  • Centrifugal flyball governor for regulating the speed of a steam engine invented by James Watt. ([5] p4, [11] p2)

    In 1788 James Watt completed the design of the centrifugal flyball governor for regulating the speed of a rotary steam engine. It is widely regarded as the first significant work in automatic feedback control to be used in an industrial process. The purpose of the flyball governor is to maintain constant speed of the steam engine despite any external influences such as load or steam pressure changes. The governor was able to accomplish this by sensing the actual speed of the engine and adjusting the steam inlet valve accordingly to maintain the desired speed. The speed of the engine is measured by two large metal spheres, the flyballs, on long metal rods that rotate at a speed proportional to that of the engine. As the speed of the engine increases the flyballs will swing further outward. The pendulum is connected to the steam inlet valve via mechanical connections so that it can control the amount of steam allowed. In this way the steam supply can be throttled when the speed rises and increased when the speed falls, so that the engine speed will reach a certain equilibrium under the given load. To keep the equilibrium speed constant the steam inlet valve is opened just enough to allow the required amount of steam needed to maintain this desired speed. If the speed drops due to an increase in the load, the reaction of the flyballs would be to increase the valve opening by an amount proportional to the change in speed, in order to get the speed back up to the equilibrium value. One of the minor setbacks of the Watt governor was a slight decrease in the equilibrium speed after a load increase; this offset however is a characteristic of all proportional control systems. Even though it was a major invention in control history, Watt never took out a patent for his governor; his view was that it wasn’t a new invention but an adaptation of the centrifugal pendulum. After Watt’s invention, there were many different governors patented and built, but the Watt centrifugal flyball governor remained the most successful and favoured as it performed what was required at the time. Other governors patented include William Siemens (1846,1853), Charles T. Porter (1858), Thomas Pickering (1862), and William Hartnell (1872), the aim of each being to improve on the Watt governor.

  • 1790
  • The brothers Périer of France came up with a float regulator to control the speed of a steam engine, but it was inferior to the Watt centrifugal governor, therefore not nearly as successful. ([6], [11] p115-118)

    The speed regulator designed by brothers Périer, while inferior for practical purposes (unreliable, sluggish, inefficient), was the first design utilizing integral control. Previous designs all used proportional control, which meant that any ongoing disturbances were tolerated, resulting in an ongoing control error. The integral control system, on the other hand, continues error correction until all error is eliminated. The regulator itself included a vessel into which water flowed in and out. The rate at which water was pumped into the vessel was proportional to the actual engine speed. The rate at which water flowed out was constant, and represented the desired speed. If the engine ran faster than desired, the vessel’s water level (and float) rose, causing the throttle valve to close, and thereby reducing the engine’s speed. It is this use of a float valve as a speed regulator that results in integral rather than proportional control.

  • 1793
  • Abraham Louis Breguet invented a closed-loop feedback system to synchronize pocket watches. ([6], [11] p119)

    Let us first discuss the synchronization and operation of pocket watches before this invention. Mechanical clocks keep time by means of the constantly repeated cycle of the oscillation of the escapement. This uniform cycle is accomplished by protecting the mechanism from external disturbances or by compensating for them. Changing the frequency of the oscillation varies the speed of the watch, which can be done via a regulating arm from the outside of the watch. To synchronise the watch to a chronometer, which is known to be accurate, one has to find the correct position of the regulating arm by trial and error and compare it to the chronometer. The pendule sympathique is able to do this automatically. Breguet’s system comprises two clocks, a conventional large accurate chronometer, whose only difference from a normal chronometer is that it is saddle shaped at the top, and a second clock (the pocket watch) that sits in the saddle on top of the larger clock. At precisely 12 o’clock a small pin protrudes from the chronometer to begin the synchronization process. To synchronize the pocket watch it is placed in the saddle of the chronometer before the process begins at 12 o’clock. The regulating mechanism is located in the pocket watch, the chronometer only has the projected pin. The projected pin is inserted into the watch through an opening. If the pocket watch is not synchronous with the chronometer, the movement of the pocket watch is altered, accelerated or decelerated depending on the result of the comparison, by adjusting the regulating arm of the watch's balance spring to better match the chronometer. Originally Breguet thought that the watch needed to be synchronized every night, but as it turned out synchronization was achieved in about 2 or 3 days.

  • 1799
  • Papin’s pressure regulator was further improved by Robert Delap, then Matthew Murray. ([6], [11] p85-87)

    The purpose of the pressure regulator of Robert Delap was to regulate the pressure of the steam entering the engine. However the device suffered a problem that compromised its operation. Its construction was such that it only provided on/off control; it could not reach and hold the desired equilibrium.([6], [11] p85-86)

    A few months after Delap, Mathew Murray patented his pressure regulator, overcoming the problems of the Delap regulator. A spiral-shaped cam was attached to the axel with a chain rolled around it. A weight at the end of this chain produced a torque which increased with rising pressure, and counteracted that produced by steam pressure through the rack and pinion. ([11] p86-87)

  • 1803
  • Matthew Boulton and James Watt combined a pressure regulator with a float regulator for use in their steam engines. ([6], [11] p87-89)

    The boiler’s steam pressure is measured using a vertical pipe which has one end in the boiler water, and the other open to the atmosphere. The difference in water level between the pipe and the boiler represents the boiler pressure. A float in the pipe, attached to a damper in the flue, closes the flue as pressure increases. The length of the chain between the float and the damper sets the desired pressure.

  • 1809
  • Sir Humphrey Davy demonstrated the arc lamp. ([1] p153) ([42])

    The demonstration of the arc lamp came about from several investigations that scientists were carrying out at the time concerning electricity, which were made possible by the development of the voltaic cell in 1800. The arc lamp works by bringing two carbon rods together, which are connected to a powerful electric source, and then moving them slightly apart. As the rods move apart, an arc is created between them that continues to conduct after they have been separated. This arc burns at a high temperature and causes the ends of the carbon to burn brightly. The arc lamp required constant attention to keep the gap between the rods constant, to ensure the arc did not burn out as more and more carbon burnt off the rods. The carbon arc lamp produced a very intense light, however in order to be a practical source of light automatic control of the lamps was required. This hurdle took several years before it could be overcome. At the time of Davy's demonstration, gas lighting was being used. It was well into the 20th century before a practical electric replacement for gas lighting was developed.

  • 1822
  • Mark Brunel devised a spring-loaded governor for marine steam engines. More practical versions were later developed, including that of John Bourne (1834), Thomas Silver (1855) and Thomas R. Pickering (1862). ([1] pp28,35) ([5] pp18,28)

    Ungoverned marine engines would race dangerously whenever the propeller or paddle wheel lifted out of the water in turbulent seas. However traditional pendulum governors proved unsuitable for marine engines. They were designed to operate from a vertically mounted platform, with a dependence on gravitational forces to balance the centrifugal forces on the flyball – a clearly unsuitable design for an engine operating on a rolling and pitching ship. They were also too slow to shut-off or let-on steam to meet the demands of the marine application.

    Brunel’s design (1822) is noted as the first design aimed at the marine engine. The more practical design of Thomas Silver (1855), also a spring-loaded governor, used 4 balls such that the added flyballs provided the balance for the original two, with a helical spring mounted on the governor's axis to provide the restoring force. Similar designs were created by a number of other inventors.

    Subsequent designs, such as that by Pickering, used smaller weights which could operate at very high speeds, resulting in a physically smaller, accurate and reliable governor, suited to many applications, including steam turbines and chronometric regulators.

  • 1824
  • Joseph Von Fraunhofer constructed a large telescope at Dorpat. It’s constant rotation (synchronous with that of the earth), was driven by clockwork and regulated by a friction governor. ([1] p58)

    Joseph Von Fraunhofer designed and constructed a large parallactic refractor at Dorpat for the Imperial Russian Observatory. His telescope rotated at a constant speed to compensate for the earth’s movement. This was the first practical application of such a design. Unlike that described by Hooke (1674), Fraunhofer used a friction governor for the clockwork speed regulator, with the change in centrifugal force used to vary the friction opposing the motion of the governor.

    The regulator consisted of a vertical axis with horizontal cross arms. At the end of these arms were springs with small weights at the ends. The regulator was then encased by a drum. As the regulator rotated, the centrifugal force of the balls bent the springs until they just touched the inner surface of a drum (determinate velocity). If velocity increases, balls press against the drum creating friction and reducing velocity until the balls only just touch the drum again.

    Note that this design results in small-amplitude, high-frequency oscillations in speed. For steam engines this would be smoothed out, but on a telescope, the result is magnified through the optical system.

  • 1840
  • George Biddell Airy built a feedback device for a telescope to compensate for the earth’s rotation. ([6]) ([1] p57).

    The purpose of Airy’s device was to turn the telescope automatically to compensate for the earth’s rotation, so that a certain star could be studied for an extended period of time. Essentially the device was a speed control system that rotated the telescope slowly at a uniform speed by the use of a friction governor. The use of a friction governor introduced oscillations into the system, these oscillations would be smoothed out by a steam engine, but a telescope magnifies them. This led Airy to be the first to discuss the instability of closed loop systems and the first to use differential equations in their analysis.

  • 1848
  • George Henry Corliss built the first successful automatic release cutoff control for the valve gear of a steam engine, resulting in greatly improved engine efficiency. ([5] p8-9).

    Steam engines using Watt’s governor for speed regulation changed the rate of flow of steam into the engine in order to decrease pressure, energy and consequently speed. Thus, steam was constantly being supplied, just at varying rates. The new approach aimed to supply steam to the engine at full pressure, but for only part of the engine’s stroke. This was a more efficient method of regulating engine speed. The valve gear with automatic cutoff, such as that designed by Corliss, used a trigger mechanism to disconnect the linkage that opens the inlet valve at the desired point in the engine stroke. If the engine began running too fast, the inlet valve was released earlier, allowing less steam into the engine during the stroke, and consequently decreasing pressure and speed. Conversely, to speed up the engine, the inlet valve was left open longer.

  • 1851
  • H.A. Luttgens patents his steam engine speed regulator incorporating integral control for greatly improved accuracy. ([5] p16-17)

    The steam-engine speed regulator patented by Luttgens in 1851 had three main features which set it apart from others of the day. Firstly it used positive cutoff control. At excessive speeds, the governor’s flyballs rise causing belt braking to be applied. This produces torque in the opposite direction and as a result, increases the throw of the eccentric. The result is earlier cutoff of steam supply to the engine and the engine slows down. At slower speeds, when the brake is off, the friction clutch drives the transmission forward so as to reduce the throw of the eccentric. In this case the steam is cutoff later in the engine’s stroke, allowing it to accelerate.

    Its second feature was a mechanical servo-power drive. This allowed the energy required to perform the controlling action to come from the crankshaft of the engine, not the governor itself.

    Finally, its most noted feature was its use of integral control. While traditional governors used the difference between desired and actual speeds to cause a one-time change in valve position with correction proportional to the error, an integral controlled device continues to make adjustments until the steady-state error is zero with correction proportional to the time integral of the error. The result is very high steady-state accuracy.

    While these features provided many advantages, it also featured poor dynamic behaviour. As a result, integral controlled governors were unpopular, but were later combined with proportional control to create governors with the advantages of both types.

  • 1852
  • Leon Foucault described the gyroscopic compass. ([5] p101)

    The French physicist Leon Foucault first described the gyroscopic compass in 1852. It consisted of a gyroscope with two degrees of freedom. Foucault found that if a weight were suspended from the inner gimbal in order to maintain the spin axis in a horizontal plane, the combined effect of gravity and the earth’s rotation would cause the gyroscope to precess until it is aligned with the meridian, pointing to the geographic North Pole. Foucault was unable to demonstrate this feature, as a gyroscope that could rotate at a high enough speed for a long enough period was unavailable at the time. During the next half-century there were many attempts to employ this effect in the construction of a compass, but it wasn’t until 1908 that H. Anschutz-Kampfe developed the first practical compass based on Foucault’s work. Later, Elmer Sperry developed his gyrocompass as an improvement on Anschutz’s design and was the most successful of the time.

  • 1857
  • The first passenger elevator, invented by Elisha Otis, was installed at 488 Broadway in New York City. ([13], [43])

    The history of the elevator can be traced back to ancient Greece, where Archimedes developed lifting devices operated by ropes and pulleys, in which the hoisting ropes were coiled around a winding drum. Medieval records contain numerous drawings of hoists lifting men and supplies to isolated locations. In 1743 a personal elevator for King Louis XV was built at his palace in France, but it was only a one-person contraption and worked by way of weights and pulleys and needed people to raise and lower it. By 1850 steam and hydraulic elevators had been introduced, but it wasn’t until 1852 that Elisha Otis invented the first safety elevator. The first passenger elevator was installed 5 years later in 1857. Today's elevators are fully automatic, using control systems to fully regulate their operation.

  • D.W. Snell and S.S. Bartlett invent and patent their “Bartlett Let-Off” mechanism for controlling and maintaining constant tension in yarn on power looms. It was implemented in the “Model A Northrop” power loom (1895) which was also famous for its automatic shuttle-bobbin changer. Similarly designed machines were also invented by Richard Walker (1867) and George Richardson (1867). ([5] p79-82)

    For high quality fabric, the tension of the yarn during weaving needed to be constant. Since the diameter of the yarn beam (on which the yarn is wound) decreases as it is used and the yarn is drawn through at a constant rate, the speed at which the yarn beam rotates therefore increases. This change in speed makes it difficult to maintain constant yarn tension. The Let-Off mechanisms designed by Snell and Bartlett, measured the tension on the yarn via a spring-loaded roller pressing against it. The distance that this roller was moved (from normal position) was assumed to be inversely proportional to the tension. This measurement was then used to adjust the speed at which the yarn beam rotated – increased for high tension and decreased for low tension. Speed was adjusted by altering the length of the ratchet stroke which rotated the yarn beam.

  • H.N. Throop greatly improved the response of the marine-engine governor, designing a spring-loaded governor with proportional-plus-derivative response. ([1] pp27-29) ([5] p19)

    The spring-loaded governor designed by Throop was a significant advancement in the design of marine engines. His design featured several weights around the circumference of a frame, arranged symmetrically so as to neutralize the effects of gravitational forces. A spring on the axis provided the centrifugal force.

    A key feature of this design was in the radial plus tangential movement of the flyballs, resulting in a proportional-plus-derivative response. Radial movement was proportional to speed, enabling it to respond to centrifugal forces. The tangential motion was proportional to acceleration, providing response to inertial forces. Consequently, the governor was able to quickly respond to the problem of engine racing (occurring when the propeller or paddle wheel lifted out of the water in turbulent seas). While the engine speed is suddenly increased in such conditions, the inertia of the weights of the governor causes the flyballs to fall back (from the radial line), and therefore outwards. As a result, the throttle valve is instantly closed. With the need for rapid response to sudden changes in engine speed being a major problem with marine engines at the time, Throop’s design was of particular significance.

  • 1858
  • Porter designed a loaded governor for high speed operation. The design was implemented in the Porter-Allen high speed steam engine (1881), leading to his reputation as the “father of the high speed engine”. ([1] pp29-34) ([5] pp13-15)

    While Porter was not the first to add weights to the traditional pendulum governor for the regulation of speed in a steam engine, he was the first to use such an approach to produce a high speed engine. The design he patented in 1858, with its very light flyballs, included counterweights to balance the centrifugal forces and increase the sensitivity of the device to small changes in speed. Using these smaller flyballs, his design featured greatly increased operating speeds, motion which was instantaneously powerful and responsive to sudden load changes, improved stability and accuracy, and reduced engine oscillation, and was a significant improvement on the traditional governors being used.

    The governor was later implemented in the Porter-Allen high speed steam-engine (1881), leading to Porter's reputation as the “father of the high speed engine”. J.F. Allen’s automatic cutoff gear (1862) was (unlike others of the time) suited to this high-speed design, featuring positively controlled variable cutoff, and a valve movement speed which was dependent on engine speed (rather than being constant).

  • 1866
  • J. McFarlane Gray patents first steam powered ship steering engine incorporating feedback. ([1] pp98-100)

    Traditionally, the helm of ships was operated manually. In large ships and heavy seas, the forces on the rudder were great, requiring a large number of men to turn the ship. When large gear ratios were used between the rudder and helm to help compensate for these forces, steering became imprecise and unresponsive. For warships, this problem was of particular importance. From this need came the motivation to use steam power to steer ships.

    While Frederick E. Sickels (1849) is attributed with inventing the steam steering engine, it was Gray in 1866 who was the first to patent a steering engine which incorporated feedback. In Gray’s design, the helm was connected via a bevel gear to the input shaft of the engine. As the helm was moved, the input shaft rotated, turning a pointer which indicated the desired rudder angle. The differential screw then moved linearly, opening the steam valve, and providing power to the motor which moved the rudder. While the input was held constant, any rudder movement was transmitted through the crown wheel and bevel gear, moving the differential screw (and pointer showing actual rudder angle), and closing the steam value. The resulting system was a true servo-mechanism.

  • 1867
  • Robert Whitehead demonstrated the first self-propelled torpedo. ([1] p119)

    Robert Whitehead first demonstrated the torpedo in 1967 to the Austrian government. It was described as a weapon that ran at a chosen depth below the surface, was propelled by a pneumatic engine, was completely independent of the firing vessel, and carried an explosive charge. This was the first demonstration of the self-propelled torpedo. The depth of immersion was sensed by the use of a hydrostatic valve, and the movement of the valve used to control the horizontal rudders. In 1869, this was improved to make the setting of the horizontal rudders proportional to the attitude as well as the depth of the torpedo. With the rate of depth proportional to the attitude, this effectively introduces velocity feedback into the depth control system.

  • 1868
  • J.C. Maxwell analysed the stability of Watt's flyball governor. ([2] p12)

    From the early history of the governor, there were reports of instability caused by the governors. This led to many attempts to try to determine the conditions for stable operation of the governor; two of the more notable names to attempt this problem are J. V. Poncelet, and G. B. Airy. They were able to show how the dynamic motion of the governor could be described by differential equations, but were unable to describe the conditions for stable behaviour. It wasn’t until 1868 that James Clerk Maxwell published his famous paper “On Governors”. In his paper, Maxwell describes how to derive the linear differential equations for various governor mechanisms. It was known at the time that the stability of a dynamic system was dependent on the location of the roots of the characteristic equation; a system is considered unstable if the real part of a complex root became positive. The problem faced was finding the location of the real parts of these roots without finding the roots of the equation. Maxwell was able to show that, by examining the coefficients of the differential equations, the stability of the system could be determined. He was able to do this for second, third, and fourth order equations, while for fifth order equations he gave two necessary conditions that had to be met. ([24])

  • Jean Joseph Léon Farcot patents his “servomechanism” for the steering of steam engines. ([1] p101)

    Jean Joseph Léon Farcot may have equal claim with Gray as the inventor of the steering engine incorporating feedback for his design patented in 1868, with the word “servomechanism” derived from his work. His design was a result of his attempt to devise a governor sufficiently powerful to operate the valves of 500 to 1000 h.p. marine engines. Farcot’s design uses a lever for input. If this lever is moved left, by means of a bell crank a slide valve is opened, allowing steam to flow to the right-hand-side of the piston. The piston is connected via a slider crank to a shaft which is connected to the rudder. As the piston moves left, the rudder is moved. Once the arm being moved is again vertical, the slide valve is closed, completing the rudder movement.

    By 1872, his steering engines were fitted to 5 small ships in the French Navy and also used for rotating gun turrets. Farcot published this and various other servomotor steam steering designs in his book “Le servo-moteur ou moteur asservi” (1873). Not only did his designs and inventions have practical importance, but his book is also the first extensive account of the general principles of position control mechanisms.

  • 1870-84
  • Commander John Adams Howell worked on and developed the Howell torpedo. ([1] p121, [5] p100)

    Between the years of 1870-1884, Commander John Adams Howell worked on and developed the Howell torpedo. This torpedo was in some areas superior to the Whitehead torpedo, for instance it contained better directional stability, it was quieter, and it did not leave a trail of bubbles behind it making it harder to detect. The torpedo was powered by the energy of a heavy flywheel that was spun to a speed of 10,000 rev/min before launching the torpedo. The depth control of the Howell torpedo is fundamentally derived from the Whitehead torpedo, except it utilises a mechanical servoamplifier, which is powered from the flywheel, instead of the pneumatic servoamplifier used in the Whitehead torpedo. The main advantage of the Howell torpedo is the directional control that it is able to obtain. The flywheel is mounted in the middle of the torpedo and spins on a horizontal axis perpendicular to that of the torpedo. It acts as a constrained gyroscope therefore it detects and responds to all horizontal forces that could deflect the torpedo from its course by rolling the torpedo about its horizontal axis. A pendulum, working through a mechanical servoamplifier, then detects this angle of roll and operates the rudder to return the torpedo back to the correct course. This use of the gyroscopic principle appears to be its first successful operation in a control system.

  • 1877
  • Edward J. Routh developed the Routh criterion for determining stability, known today as the Routh-Hurwitz criterion. Adolf Hurwitz also did this independently in 1895. ([6], [24])

    Edward J. Routh attacked the problem left by Maxwell of finding a numerical technique to determine the stability of the roots of higher order equations. In 1877 he produced his work “Stability of Motion” in which he looked back on the work of Augustino-Louis Cauchy and Charles Strum to develop what is known today as the Routh-Hurwitz criterion. In 1895 Adolf Hurwitz, who was approached by his friend A. B. Stodola for help on a turbine control problem, derived the criteria independently unaware of the work of Maxwell and Routh. His work was based on some of the results of C. Hermite. [24]

  • 1884
  • Charles A. Parsons invents the first practical steam turbine aimed at powering ships. ([5] p45-47) ([50])

    Charles Parsons is credited as the inventor of the first practical steam turbine in 1884. Realizing the need for a rotating machine or turbine to convert the power from steam directly into electricity, he built his first multi-stage reaction turbine. Parsons used an unconventional mechanical method of speed control for the engine. A centrifugal fan was used as the speed-sensing device, creating on its suction side a vacuum approximately proportional to speed. A large spring-loaded leather diaphragm connected to the vacuum linked by a rigid rod to the throttle valve so as to reduce steam flow to the turbine as speed increased. The system also featured electrical fine adjustment. A metal pipe connected to the vacuum system had its opening at the top of the generator. A spring-loaded baffle pivoting in front of this opening was actuated by the magnetic field of the dynamo. For increasing voltage, the vent hole closed, causing an increase of vacuum and therefore a decrease in turbine speed. For decreased generator output, the vent opened, the vacuum decreased, and therefore the throttle valve opened and speed increased. Seeing the potential of steam turbine driven electrical generators, Parsons also designed the turbo-generators. Early designs had an output of around 1 to 75 kW. By 1895, three 4 ton 100 kW radial flow generators were installed in the Cambridge Power station, supplying power for the first electric street lights in that city.

  • 1885
  • First point in history for remote-controlled naval vessels to appear. ([23])

    A boat was electronically controlled and steered remotely by an operator on board the British torpedo ship Vernon. The lack of technical developments at the time made full-scale development of the project impractical.

  • 1887
  • Chichester Bell and Charles Tainter improved on Edison’s Phonograph (1877) with the Bell & Tainter Graphaphone ([5] p65-68)

    Since tone reproduction quality was greatly dependent on maintaining a uniform turntable rotation speed, the use of a friction governor made a significant improvement in the quality of sound produced. The governor was mounted separately to the rest of the gramophone, and connected via a belt. It had two flyweights which, for an increase in turntable speed, swung out creating a breaking mechanism which slowed the rotation of the turntable.

  • 1892
  • A.M. Lyapunov studied the stability of non-linear differential equations. ([6])

    The Lyapunov theory was one of the first approaches to the qualitative analysis of the behaviour of non-linear dynamic systems. It was proposed that one could use Lyapunov functions not only for system stability analysis, but also in the design of stabilizing controllers. It was also realized that one could also utilize Lyapunov functions to analyse system performance. These realizations opened the door for using Lyapunov functions to design controllers for non-linear systems to achieve not only stability but also certain performance objectives. Even with these benefits the Lyapunov theory was not utilized or known in the West until about 1960, but his work continued to be used in Russia.

  • 1895
  • As an improvement to the torpedo, Ludwig Obry invented a gyroscopic device that was used for the directional control of the torpedo. ([1] p122, [5] p99)

    The purpose of the Obry gyroscope is to improve the directional control of the torpedo by correcting any deviation, bringing it back to its desired course. Any movement of the torpedo from its set course is detected by the outer gimbal of the gyroscope. This movement of the outer gimbal is then used to operate the vertical rudders to bring the torpedo back to the set course. Therefore the Obry gyroscope is used to detect and then correct any deviation of the torpedo. The Obry gyroscope was fitted to the Whitehead torpedoes one year later in the U.S., and 2 years later in Britain.

  • 1898
  • Nikola Tesla built his propeller-driven radio controlled boat, considered the birth of all remotely operated vehicles. ([46])

    In May of 1898, Nikola Tesla publicly demonstrated his propeller driven radio-controlled boat at Madison Square Garden in New York. His 'Telautomaton RC boat' is considered to be the original prototype of all modern day remotely operated vehicles either by air, land, or sea. Lead acid batteries and an electric motor powered the vessel, while it received instructions via a wireless remote control transmitter. The boat was designed to be moved up alongside the intended target then, upon command, detonate an explosive charge located in its forward compartment. The system also had a secure communication link between the controller and the torpedo to ensure control could be maintained in the presence of electronic countermeasures.

  • 1903
  • (17 December) The Wright brothers demonstrate the first truly controlled, sustained, powered, and heavier than air flight. ([44])

    The Wright brothers were not the first to fly. Before them there was the hot air balloon, invented by Jean Michel Montgolfier, the gliders of George Cayley and Otto Lilienthal, as well as many other hopeful attempts at flight. In 1884, Octave Chanute published a book “Progress in Flying Machines” in which he wrote about all the information available about these ideas and experiments. In 1899, the Wright brothers read Chanute’s book and their journey began. The Wright brothers were the first to demonstrate controlled, powered, sustained, and heavier than air flight. The key to their success was the use of wing warping, which effects lateral control, giving them control of the plane for turning. The idea of wind warping is one of three major contributions of the Wright brothers. They also introduced the first practical wind tunnel on which they tested prototypes before building full-scale versions. Perhaps of most importance was the compromise between controllability and stability. By having an operator in the loop, they were able to perform controlled flight even though the open-loop system was slightly unstable. The contributions of the Wright brothers were the beginnings of today’s modern aeroplanes and space shuttles.

  • 1909-1911
  • Elmer Ambrose Sperry developed his gyrocompass, which was an improvement over the Anschutz designed compass. ([5] p101, [54])

    From 1909 to 1911 (1910 developed the gyroscope for ship control) Elmer Sperry worked on and developed a gyrocompass that had greater sensitivity then the Anschutz design. Like many before him, Sperry’s compass was based on Foucault’s theory. A simple description of the compass is given below. It consists of two parts the sensitive element and the follow-up system. The function of the sensitive element is to precess the wheel until it points to the correct position, but it is not powerful enough to drive the indicating devices on the compass. This is where the follow-up system comes into effect to increase the power and display the output. The Sperry gyrocompass could be used as a master and transmit to several repeater compasses located at different positions around the ship.

  • 1910
  • Elmer A. Sperry invented a gyroscope for use in the stabilization and control of ships. ([6], [1] p125)

    Elmer Ambrose Sperry was able to apply the gyroscope to improve the stabilization and control of ships. In order to detect the rolling of the ship Sperry used a sensor. The sensor in turn operated a motor that caused the gyroscope to precess and generate a torque that opposed the roll. Sperry used a simple pendulum as the sensor and to transfer the activity of the sensor to the controller he used what he referred to as 'the phantom' (see more information). In this device Sperry has used feedback to obtain proportional action from a relay system. This was the first of the works that led to today’s autopilots.

  • 1912
  • Elmer A. Sperry began work on the Sperry gyropilot, an automatic steering system for ships. ([1] p130 and [5] p102)

    Considered his most famous invention, Sperry’s gyropilot was not the first of its kind but it was the most successful. In the 1870’s Werner Siemens had the idea for the automatic steering of a torpedo boat. He began trials of his idea in 1872, using an electric motor, operated through magnetic relays; he was able to turn the rudder of the boat in the desired direction. The operation of the boat could either be carried out by a station on land connected to the boat via light cable, or a magnetic needle of a compass located on the boat. With the introduction of steering engines began the attempts to connect the steering engine to the magnetic compass of the ship to create an automatic steering system. Some of those involved in this were A.B. Brown, Sir James B. Henderson, Elphinstone, and Wimperis. However the main contributor to the development of the automatic steering system was Sperry. Sperry was able to combine the gyrocompass with the steering system of the ship to develop the Sperry gyropilot, which had the capability of replacing the helmsman. The foundation of the Sperry gyropilot is an electric motor that could be rotated in both directions or held motionless by a 3-position controller. The motor controlled the wheel, which in turn operated the rudder by the normal steering engines of the ship, thus the gyropilot had control of the steering of the ship. Sperry incorporated in his design the effects of the helmsman to improve the performance of the gyropilot. Officers aboard one of the ships used for trials named the gyropilot ‘Metal-Mike’.

  • 1913
  • Henry Ford introduces a mechanized assembly line for automobile production ([21])

    The Ford motor company introduced its model T Ford in 1908. It was so successful that demand soon became too great for production. Ford needed to look at new ways to speed up its production, and the answer came in the form of a moving assembly line. Henry Ford introduced his famous assembly line in October 1913. This was the first of its kind and marked a revolutionary change in the way factory assembly was done. The purpose of the assembly line was to speed up the manufacturing process. The Ford assembly line was a moving 250-foot long line where each worker would perform a specific task over and over again on each car as it slowly passed by. Workers did not have to waste time moving around as parts were also delivered to them by way of a conveyor belt. The new system meant that a complete new car could be produced in just three man-hours. The new technology was a huge success and propelled the Ford Motor Company to the forefront of car manufacture in the world.

  • 1914-18
  • The Germans built 17 FL-7’s, electronically controlled motorboats, for coastal defence. ([23])

    The vessels known as FL-7's were 14.9m in length and were powered by 200-hp gasoline engines. They reached speeds of up to 30 knots and carried enough fuel to operate for 6 hours. Their range was limited by the visibility of the controller sitting at the 30.5m high control station who could manoeuvre the boat 24km away from the shore. The boats were steered by electricity transmitted through an insulated cable that could reach a length of 80km. The boats carried up to 202.5kg of explosives, which would destroy the target and the boat upon contact.

    By 1916, the control range of the unmanned boats had doubled, with a seaplane used to signal the operator the direction to manoeuvre the boat. This type of weapon did have some success, but repeated failures of the cable-controlled boats paved the way for radio-controlled boats.

     

  • 1914
  • Lawrence Sperry demonstrated the displacement gyroscope (airplane autopilot) for planes that had been developed by his father Elmer Sperry. ([10] p63)

    In a competition to demonstrate new technology for making flying safer, Lawrence Sperry, on June 18, piloted a Curtis flying machine along with his mechanic Emile Cachin to display the autopilot developed by his father Elmer Sperry. While in the air Lawrence stood up and placed his hands on his head, while Cachin walked onto the lower wing. At this point it was expected that the plane would roll out of control, instead they observed the beginnings of the autopilot and a new era in flight. The ailerons of the plane moved automatically to correct for the roll and the plane was able to maintain level flight. As soon as the plane deviated from level flight the gyro closed an electrical circuit. This in turn powered a valve that released compressed air, whose force was able to move the elevator and ailerons to compensate for the roll and bring the plane back to level flight. Sperry’s revolutionary new system connected the gyro and the ailerons in a feedback loop capable of stabilizing the airplane without any input from the pilot. The gyro has since had a profound effect on the history of flight and navigation; in many respects without the gyro space travel would not have become a reality.

    The following is a quote from Bernstein (2002 [10] p63) on the effect the gyro has had on history. The development of the gyro for determining angular displacement and angular rates created the ability to perform navigation without using external signals such as radio beacons, magnetic compasses, or optical sighting. Gyrocompasses provide the means to determine heading, while the signals from the rate gyros and accelerometers can be numerically integrated to determine location. These devices were essential to the development of missile guidance, submarine navigation, and space navigation technology. In addition, feedback control loops based on gyros have been used in autopilots for pilot assistance or fully autonomous operation. In short, the gyro opened the door to the space age.

  • 1918
  • E. E. Wichersham designed and developed a demolitions carrier called the Land Torpedo. ([23])

    The development of the Land Torpedo was considered the dawn of the world of robotic ground systems. E. E. Wichersham, who worked as an engineer with the Caterpillar Tractor Company, designed and developed a demolitions carrier to be called the Land Torpedo. The Land Torpedo was powered via a battery; it received and followed directional signals relayed by cable, however the Land Torpedo was never employed on the battlefield.

  • (March 6) The first successful flight of an unmanned and not radio controlled aircraft. ([23])

    Elmer A. Sperry, who developed the displacement gyro used for the stabilization of the aircraft and for autopilot implementation, was approached by the U.S. Navy to carry out work on "aerial torpedoes". A Ford 40-hp engine that was automated by Sperry powered the Curtis plane used in the project. The plane weighed 225kg, could travel at speeds approaching 144kph for a distance of 80km and was pilotless. The Curtis flying bomb was flown by presetting the gyroscope for direction and the aneroid barometer for altitude. Once the plane reached the estimated distance to the target the engine was stopped and a mechanical device removed the bolts holding the wings. The fuselage carrying the explosive would then drop on the target. On March 6, 1918 the Curtis flying bomb flew a prescribed course of about 900m making it the first successful flight of a robot aircraft.

    British interests in pilotless aircraft were renewed in the 1920’s, but failed to deliver the desired results. Efforts were then turned back to remote-controlled aircraft in the 30’s and 40’s. Of these the most famous were the British Queen Bee and the American Fiesler 103 or the V-1 Buzz Bomb.

  • Early 1920s
  • The U.S. Naval Research Laboratory built a remote-controlled ground vehicle, the Electric Dog. ([23])

    The Electric Dog was considered an early pioneer of remote-controlled ground vehicles. It is a 3-wheeled cart improvised from a tricycle and driven by a series of small motors supplied from a storage battery. The radio-controlled system was an enhanced version used in the German unmanned torpedo boats and the control switch was similar to the control stick of the planes at the time. The technology of the vehicle, which comprised of 4 circuits controlling the cart were connected for forward, reverse, and right and left turns, demonstrated the successful simultaneous and independent operation of control circuits. The technology was used by the Navy as a test for remote control of aircrafts and target ships rather than to develop unmanned ground systems.

  • 1922
  • Nicholas Minorsky presented a clear theoretical analysis for the automatic steering of ships; he also developed a three-term controller, thereby becoming the first to use the proportional-integral-derivative (PID) controller. ([6], [24])

    In 1922 Minorsky, through observing the way a helmsman steered a ship, presented a clear theoretical analysis of the automatic steering of ships. Minorsky introduced the control law that is now known as PID control. Minorsky’s contributions to control theory however did not become widely known until the late 1930’s after he had written a series of articles for The Engineer.

  • 1927
  • Harold Stephen Black invented the negative feedback amplifier in order to reduce distortion in repeater amplifiers used in telephone systems. ([6], [10], [24], [25], [45])

    In the 1920s amplification was causing problems and holding back the further development of long distance telephone systems. Improved cable lines and the use of impedance loading had extended the distance with no amplification needed, but long distance systems were dependent on the amplification process. Up until this point this was achieved via telephone repeaters that were based on the electronic amplification of the signal, but with each amplification, distortion was introduced into the system so the number that could be used in series was limited to the amount of noise that could be introduced into the system whilst maintaining a satisfactory signal. Harold Stephen Black began to tackle this problem in the early 1920s. The first solution he came up with was in March 1923, a repeater based on this idea was built and was found to function as required. However this approach was unsuitable for amplification, as it needed two exact amplifiers to function and this was not possible without constant human input to correct for component drift. Black finally arrived at a practical solution on the morning of the 2nd of August 1927 while on the ferry on his way to work. He wrote his theory on a page of The New York Times signed and dated it and had it verified by a colleague on his arrival to work. Black’s theory involved feeding back part of the output signal, in negative phase, into the amplifier and comparing it to the original signal. This proved to greatly reduce the distortion due to noise and component drift by sacrificing a small amount of the amplifier gain. Trials were carried out in 1930 and just a year later AT&T began using the amplifier. Although the idea was successful it took nine years for the patent application to be granted. There were questions about purposely lowering the gain of the amplifier and questions about the stability when the open loop gain was greater than unity as it was well known at the time that oscillations occurred in high gain positive feedback amplifiers. Harry Nyquist satisfied the stability question with his paper "Regeneration Theory" in 1932.

  • 1932
  • Harry Nyquist developed his regeneration theory as a result of investigating the conditions for which a feedback amplifier is stable. From this he derived his Nyquist stability criterion. ([6], [10], [24], [26])

    The "Regeneration Theory" paper by Harry Nyquist came about from a request from Harry Black for assistance in understanding the conditions under which his feedback amplifier is stable. The essential part of Nyquist's paper is the understanding that the behaviour of a system can be analysed in terms of its frequency characteristics and that all impressed signals can be described in terms of their Fourier components. In all, Nyquist was able to generate a theory that determined when negative feedback amplifiers are stable. The paper ultimately led to a method of analysing and designing control systems without the use of differential equations. The measured frequency response could be combined with the calculated data and from the combined response the degree of stability of the system could be estimated; therefore any changes that can improve the performance can easily be found. The techniques are known today as the Nyquist Stability Criterion.

  • 1935
  • British physicist Sir Robert Watson-Watt produced the first practical radar. ([32])

    The radar can be traced back to James Clerk Maxwell, who developed equations governing the behaviour of electromagnetic waves. The laws of radio wave reflection were present in Maxwell’s equations and were first demonstrated by Heinrich Hertz in 1886. The idea of the radar came several years later with Christian Huelsmeyer proposing a detecting device that uses radio echoes to avoid marine collisions. However it wouldn’t be until 1924 that the first successful experiment took place. Since the ionosphere reflects radio waves, Sir Edward Victor Appleton used radio echoes to determine the height of the ionosphere. Eleven years after this the first practical radar was invented by Sir Robert Watson-Watt. By 1939 England had a series of them along its south and east coasts to detect any attack by land or sea. The British were again responsible for the next advancement in the radar, when in 1939 Henry Boot and John T. Randall invented an electron tube called the resonant-cavity magnetron. This invention paved the way for the development of the microwave radar, which is used in today’s communications.

  • 1938
  • Hendrik Wade Bode was able to investigate stability using the magnitude and phase frequency response plots of a complex function, known today as Bode plots, he also introduced the notions of gain and phase margin. ([6], [26])

    Bode’s work continued along the lines of the work done by Black and Nyquist. In fact he was responsible for rotating the Nyquist diagram making (–1, 0) the critical point rather then (+1, 0) as it originally was. Bode’s significant work was the investigation of closed-loop stability using the notions of gain and phase margin, which he introduced. Bode put forward that the theoretical condition for stability, i.e. the phase shift must not exceed 180° until the loop gain is reduced to one or less, was not sufficient. He believed that the limiting phase angle must be less than 180° by some amount, which he called the phase margin. Similarly he claimed that it is impossible to restrict the phase shift to less than the maximum specified once the frequency increases beyond the required bandwidth. Therefore for a stable system the gain must be reduced; the gain margin is referred to as the amount by which the gain is less than 1 at a phase shift of 180°. Today Bode plots are used extensively with many electronic systems.

  • 1939
  • The Borgward Company in Bremen, Germany began the development of the B1V Demolition Vehicle, the first operational remote-controlled land vehicle. ([23])

    Picking up where the United States left off with the electric dog, the Germans developed the first operational remote-controlled ground vehicle. The B1V, a small 3660 kg vehicle was used for remote detonation of mines. The vehicle was driven until it was considered unsafe, then the B1V would resume its mission via radio remote control. The vehicle was supposed to reach its target, release a charge with a delay device and back away. The charge and detonation of the mine was not supposed to happen until the vehicle reached a safe distance. This was not always the case as the delay mechanism occasionally failed, resulting in the destruction of the B1V by the detonating mine. Throughout World War II, 500 B1V demolition vehicles were built. The Borgward Company also developed the Goliath Demolition Vehicle, which was used for demolition and mine clearing. This vehicle was designed to be cheap and expendable and therefore was sacrificed upon detonation.

  • 1940
  • The British firm W. H. Allen & Company, with A. C. Hutchinson and F. S. Smith, designed the first military related walking machine. ([23])

    The design was a four-legged, thousand ton tank, whose leg suspension function allowed it to operate effectively on uneven ground. It was controlled via an operator who used his feet on pedals to control the two hind legs and his hands on handles to control the forelegs. The model was successfully able to climb over a pile of books, but its funding was cancelled by the U.K. War Department to focus on other programs.

  • David B. Parkinson (Bell Telephone Laboratories) designs anti-aircraft gun controller, with production starting early 1943. ([7] p8, [26] p126,171)

    Parkinson suggested the idea of connecting the radar, the position predictor and the actual gun controller together to form an integrated control system instead of having the information passed manually. Parkinson had the idea of linking the components together to form a system but he was not responsible for the overall design of such systems. Parkinson’s antiaircraft gun controller used radar for its input. The controller then calculated the necessary position using the detected aircraft’s current position and prediction of its future one. The gun was then aimed accordingly.
    The work on the BTL predictor began in 1940 and was led by Bode. This predictor was in 1943 linked to the SCR-584 designed in the Radiation Laboratory at MIT and to anti-aircraft guns.

  • 1941
  • Albert C. Hall recognized the harmful effects of ignoring noise in control system design, while designing an airborne radar. ([6], [26])

    Albert C. Hall was part of a servomechanisms group that realized that the frequency-domain technology developed at Bell Labs, for communications purposes, could be employed to analyse high order servomechanisms instead of using the difficult differential equation approach. Hall worked with George C. Newton and the Sperry Gyroscope Company on the design of an auto-track radar, in which only the radar aerial tracks the target automatically - the whole system does not function automatically. Towards the end of 1941, the control system for the project had been designed, but fluctuated because they had ignored the importance of noise. Using the frequency-response techniques the group was able, in three months, to modify it to produce a stable control system with a satisfactory transient response and less fluctuations. Their success using frequency-domain techniques proved the importance of the frequency techniques in control system design.

  • 1942
  • (October 3) The beginning of the modern day missile with the launch of the first V-2 (originally called A-4) missile by Wernher von Braun and Walter Dornberger ([29])

    The launch of the first V-2 missile marked the launch of the world’s first unmanned guided ballistic missile and the first rocket to ever go to the fringes of space. The V-2 used a gyroscopic system that sends signals to aerodynamic steering tabs on the fins and vanes in the exhaust. The vanes were controlled individually by the guidance and control of the missile, allowing control of movement in three directions: roll, pitch, and yaw. The single stage rocket is fuelled by alcohol and liquid oxygen, generating about 25,000kg of thrust at the start and increasing to about 72,500 when the maximum speed was reached. The motor burned for 60 seconds pushing the rocket to 1341m/sec, an altitude of 83 to 93km, and a range of 321 to 362km. The V-2 carried an explosive warhead weighing about 738kg. Its first use in combat was on September 8, 1944.

  • 1945
  • Cruise control invented by Ralph Teetor. ([8])

    Although blind from the age of 5, Ralph Teetor invented, among other things, cruise control for cars. The idea came from a bumpy car ride with his patent attorney who kept on accelerating and slowing down while talking. Teetor claimed he would never have worked on it if not for this jerky trip. The cruise control system controls the speed of the car by adjusting throttle position. The throttle valve controls the power and speed of the engine by limiting how much air the engine takes in. By the 60s cruise control was a regular feature on all major manufacturer's cars.

  • 1947
  • Nathaniel B. Nichols developed his Nichols Chart. ([6], [26])

    A problem frequently faced by designers was the calculation of closed loop linear system response from open loop transfer characteristics. Algebraic calculation of the maximum closed loop system gain and frequency at which that gain occurred was somewhat tedious. It was from this need that the graphical design aid was created which we now call the Nichols Chart. The Nichols Chart is a tool for the designer to read off closed loop gain and phase directly from a plot of open loop logarithmic gain and phase, parameterised by frequency. It has proven to be one of the most useful closed loop system design tools in the history of the control field.

  • 1948
  • Walter R. Evans developed the root locus technique. ([4] p6, [28])

    The motivation behind the root locus technique developed in 1948 by Walter R. Evans, was a question asked by one of his students. The student asked ‘How large can the second time delay in a system be compared to the first one before the rules for a quadratic to be too much in error?’. [28] Evans worked on the problem and developed his graphical technique to plot the roots of the characteristic equation whose parameters changed over a range of values. The root locus technique is used in the design and analysis of transient response and system stability. The parameter ranges for system stability, instability, and oscillation can be easily found from the root locus plot. Evans also invented the spirule, a plastic protractor that enabled users to make quick and accurate root locus plots.

  • 1950
  • John Hopps invented the world's first cardiac pacemaker. His device was far too large to be implanted inside of the human body, and therefore it was an external pacemaker. ([33])

    The Canadian electrical engineer John Hopps is accredited with designing and building the first cardiac pacemaker in 1950. Far from today's small and compact pacemeakers, Hopps' was a large external device that looked crude and was painful for the patient to use. In the following years, several inventors would make smaller devices, but they were still quite large and not very comfortable for the patient. They were big, relied on external electrodes, and had to be plugged into an AC wall outlet. A couple of obvious problems for these pacemakers were the frequent external electric shocks and the possibility of the pacemaker failing during a blackout. ([33])

  • 1951
  • The Ryan Aeronautical Company produced the first jet-engine target drone, the Firebee.

    The Sperry Corporation also began converting manned aircraft into drones. During the Korean War the American’s used F6F Hellcats that were converted into drones, loaded with explosives and guided into heavily defended enemy territory. Manned aircraft were used as control planes to remotely manoeuvre the drones.

  • 1956
  • Digital computers first used to control processes. The Port Arthur Refinery began development in 1956, going online with the computer controlled system in 1959. ([51] p3)

    The digital computer controlled system measured pressure and other catalysts to determine the optimal distribution of hot water flow among the 5 reactors of the polymerization unit. The system controlled 26 flows, 72 temperatures, 3 pressures and 3 compositions.

  • 1958
  • The development of the cable-controlled underwater recovery vehicle (CURV) began at the U.S. Naval Ocean Systems Centre. ([23])

    The operation of the Vare caught the eye of the Navy who began the construction of the cable-controlled underwater recovery vehicle. Over the next 5 years the CURV was able to recover more than 600 objects, including torpedoes, and carry out some of the dangerous work usually performed by manned vehicles or divers. It generated some interest in the unmanned underwater vehicles, commonly referred to as Remote Operated Vehicles (ROV).

  • 1959
  • Work begins on a digital computer for fully direct control of a process.

    This was initiated by Imperial Chemical Industries (ICI) who began work in 1959 with the Ferranti Company on a Direct Digital Control (DDC) scheme for a soda ash plant at Fleetwood, Lancashire. The system was based on the Ferranti 200 computer which had a ferrite core memory, programmed by inserting pegs into a plug board, each peg representing one bit in a memory. The computer could handle 256 input measurements and 120 control loops—224 and 98 of which respectively were used in the Fleetwood system which went live in November 1962 and ran for three years. ([53])

  • Late 1950s & 1960s
  • The U.S. Army developed several legged vehicles including the Quadroped and the ASV (Adaptive Suspension Vehicle). ([23])

    The Quadroped, built by General Electric, was not technically a robot as an operator drove it, but it did contain extensive robot-related technology. It used cybernetic anthropomorphous machine systems (CAMS) technology to mimic the operator’s movements. The operator was situated in the vehicle’s cab, where the left and right legs of the Quadroped were controlled by the operators left and right hands while the hind legs were controlled by the operator’s foot controls. There were a total of 18 separate inputs by the operator to control the machine. Hydraulic actuators, driven by high-pressure oils, were located on each leg and powered the walking truck. The 1,350 kg test vehicle was able to climb obstacles, lift a jeep out of a mud hole, and load and unload a 250kg crate of ammunition. Although the operator was able to drive the machine while blindfolded, it demanded continuous movement from the operator who was too exhausted to continue after about 15 minutes, and for this reason the program was cancelled. As this program ended researchers at Ohio State University led by Dr. Robert McGhee began to build the Adaptive Suspension Vehicle (ASV). The ASV prototype was 3.08m long and weighed 2,250kg. It was able to step over 1.85m ditches and climb over 1.85m walls. The ASV, based on a spider, had six legs and used a vertical gyroscope and pendulums to keep its body level when travelling over irregular surfaces. The ASV also mimicked the spider by using its feet to check the ground ahead, by incorporating sensors into the ASV’s feet. An onboard computer was used to choose the proper footholds; it included a laser scanning system and incorporated algorithms to coordinate its way of walking. This work was completed in the mid 80’s and led to further projects.

  • 1961
  • George Devol and Joseph Engelberger invented the first industrial robot, Unimate. ([14])

    Inspired by science fiction to create a robot, George Devol and Joseph Engelberger invented the first industrial robot, Unimate. Unimate was first used at the General Motors Plant to work with heated die-casting machines. Unimate, which is basically a 4000-pound arm, would go through step-by-step commands that were stored on a magnetic drum. Its job was to take die-castings from machines and perform welding on auto bodies. The advantage of using robots is that they work tirelessly and can be sent into hazardous and unhealthy conditions and do work that humans cannot or are simply not prepared to do. A continual development and improvement in the robots and the advances made in robot control systems have made them an essential part of industry.

  • Yuri Alexeyevich Gagarin was the first man in space on board the spaceship Vostok 1. ([20])

    Gagarin onboard Vostok 1 was the first man to be sent to space. The journey lasted 108 minutes orbiting the Earth. It proved that man could endure the severity of space travel and opened the door for future explorations.

  • 1963
  • The Applied Physics Laboratory of the University Of Washington began the development of the SPUR (Self-Propelled Underwater Research Vehicle). ([23])

    A free-swimming vehicle that was not hindered by cables, the SPUR gathered data on physical properties of the sea. Communication between the support ship and the SPUR was via transducer array that sent frequency-shifted and digitally coded signals through an acoustic link.

  • Mid 1970s
  • Cable controlled remotely operated sea vehicles were used as mine-destruction devices. ([23])

    One of the first of this type of vehicles was the Société ECA of France built PAP 104. The PAP 104 destroyed the mines by either carrying explosive charges to detonate them or by cutting their anchoring lines, and floating them to the surface for detonation. 250 units of the PAP 104 were sold to 10 different navies.

  • 1976
  • First Space Shuttle ([19])

    Rockwell International built the first space shuttle, Enterprise, in 1976. In 1977 the shuttle was put into service at NASA’s Dryden flight research centre as a test vehicle used to give pilots training and NASA insight on system and performance characteristics. Even though Enterprise is referred to as an orbiter, it never went into space, but did provide essential information and training for future voyages.

  • 1997
  • (July 4) First ever autonomous rover, Sojourner, explores Mars. Sojourner was designed by a large NASA team lead by Jacob Matijevic and Donna Shirley. ([15][7])

    The 10.5kg rover Sojourner was launched on December 4, 1996 aboard pathfinder and arrived on Mars July 4, 1997. Sojourner was fitted with sophisticated laser eyes and through automated programming was able to react to spontaneous events. Another impressive feature of the rover was its hazard avoidance system, which allowed it to make trips to designated points without the need for detailed information to warn of potential obstacles. Sojourner would stop along the way to sense the terrain and process the information it collected. For this reason it moved relatively slowly at about one and a half feet per minute. In all it travelled about 100 metres in 230 commanded manoeuvres, covering about 250 meters squared. Sojourner was able to send back vital data, including images from the lander and rover, chemical analyses of rocks and soils, and measurements of atmospheric pressure, temperature, and wind. After 83 days the team lost contact with Sojourner, which operated 12 days though its expected lifetime was 7 days.

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