As at any time of rapid technical change the understanding of the problems and the adoption of new ideas, devices, and techniques varied greatly, both between and within various application areas, and there is no single definitive path of innovation. The experience of A.L. Whiteley when he joined the Industrial Engineering department of the British Thomson-Houston Company in September 1930 epitomises the general state of industrial control technology in the early 1930s. He recalls that the department designed electrical drive systems for the steel and paper manufacture, for printing, and for mine winders, lifts, cranes, excavators and machine tools. Design was done by 'control gear engineers' and amounted to no more than the layout of the system using standard relays and contactors. Occasionally, but with great reluctance, some design and development work might be done on a new relay or contactor.

This chapter discusses the developments and the use of electronic negative feedback amplifier. The comparison in the developments in telephone and then wireless communication systems illustrates the great significance of Black's recognition that negative feedback has benefits other than simply providing stability. In examining the way in which 'feedback' has been used in radio applications, Black clarified understanding and through his realisation that the behaviour of the complete system could be modified by changing the passive components in the feedback network, he pointed the way forward. John Taplin of MIT adapted the Nyquist tools for use in general feedback systems in about 1937 when he applied the techniques to a servomechanism. The use of frequency response techniques for investigating system performance led to attempts to relate frequency and transient response data. For the dominant position occupied by frequency domain techniques for control system design. The search of the communication engineers for methods of achieving stable frequency oscillators epitomises the use of negative feedback.

This chapter discusses wartime problems. The problems like anti-aircraft fire control and the attempts made at finding solutions. Most of the control system advances arose out of work on fire-control applications, that is the detection, tracking, and prediction of the future position of a moving target, and the aiming and firing of guns.

This chapter discusses how we can determine by gathering statistical data the dynamics of the system so that we can design appropriate control devices.