Control engineering is a discipline that has in part been driven by practice, in part by theory. The earliest drivers were applications problems in the field of time measurement, mills and steam engine speed control. Major control tasks included control with zero steady state error, and achieving fast response to a step change, without instability or excessive overshoot. Work late in the 19th century provided the first formal solution to the stability problem, and an understanding of the value of integral control. A seventh order water turbine system had been successfully, and scientifically, controlled, by 1900.
In the first half of the 20th century, electronic amplifier design and then the second world war gave much impetus to the development of control engineering. The methods developed for design were predominantly graphical, and involved adjustment of only a few parameters. The role of high gain, proportional, integral and derivative control all became understood and control engineering ideas found applications throught chemical and mineral industries.
Theoretical developments in the second half of this century have been substantial. Many took some years to be translated into practice, such as LQG design, adaptive control and sampled data control. Aerospace applications requirements drove some of these developments, many of which are now finding their place also in materials processing and handling systems, as diverse as sugar cane mills and chemical process control.
Future developments will arise from applications pressure, and theoretical work. Applications pressure is strong in the areas of robotics, automobiles, discrete-event systems, environmental control ; replacement of existing nonadaptive by adaptive systems will be widespread. Theoretical developments will occur in many areas including nonlinear systems, robust control design and, perhaps, use of time-varying controllers for time-invariant plants.