The Development of Control Engineering in Britain
and the Cambridge Contribution continued...
The emergence of Control Engineering as a discipline, and the realisation
that there were common techniques and methods which could be used in a
wide variety of applications (ranging from control of power plants, chemical
processes, to aircraft stability, engines, even applications in economics
and biology), happened in the late 1930s and 1940s. A substantial part
of what came to be called "classical control'' originated in the work
on feedback amplifiers at the Bell Laboratories in America in the late
1920s and 1930s. Experience of engineers in Britain involved in key war-time
applications (such as radar fire control) helped to establish a strong
basis of expertise in the area. In 1942, a very influential committee
was formed to coordinate work and to facilitate an exchange of information:
the Interdepartmental Committee on Servomechanisms (the Servo Panel).
Several members of this committee played an important role in disseminating
control system design techniques after the war and in helping universities
to establish courses. Due partly to the Servo Panel, Britain was the first
country to hold a major international conference on automatic control
(the Cranfield Conference of 1951).
An influential figure in Britain at this time was Arnold Tustin, who
worked for Metropolitan Vickers until 1945 and became Professor at Birmingham
University (1947) and later at Imperial College (1955). In a lecture to
the Servo Panel in 1942, Tustin described the design methods developed
at Metro-Vick for gun control, which used the frequency response locus.
The connection with the Nyquist stability criterion and work going on
in America was later drawn to Tustin's attention by P.J. Daniell of the
Mathematics Department at the University of Sheffield. (Incidentally Daniell
was one of several people to independently develop the describing function
method in the 1940s; this is one of the topics taught in the I3 module
in the fourth year of the Engineering Tripos). Another influential member
of the Servo Panel was A.L. Whiteley who developed the use of inverse
Nyquist diagrams for feedback design in 1943 at British Thomson-Houston
Company (in parallel with H.T. Marcy in America). It seems that the experience
gained by early British designers in the use of frequency response methods
had a strong effect on the subsequent development of control in Britain.
It is possible that this influence extends to later research on multivariable
control design and H-infinity control.