Windup in Control

Actuator saturation is probably the most frequent nonlinearity encountered in control applications. Input saturation leads to controller windup, removable by structural modification during compensator realization and plant windup which calls for additional dynamics. Peter Hippe presents solutions to the windup prevention problem for stable and unstable single-input-single-output and multiple-input-multiple-output (MIMO) systems. The solutions use only standard tools for the investigation of linear systems - state equations, transfer functions, etc. The stability tests are based on well-known criteria for loops consisting of a linear part with isolated sector-type nonlinearity. Less rigorous "engineering solutions" which guarantee improved performance but without strict proof of stability are also demonstrated. MIMO systems in which the behaviour of controlled variables is decoupled require specific input vectors and so also suffer problems of directionality when their input signals saturate. This can have extremely deleterious consequences for closed-loop behaviour. Windup in Control offers an exact solution to this directionality problem for stable and unstable systems. The methods laid out in this survey also integrate solutions for applications with rate-constrained actuators and for bumpless transfer from manual to automatic during system start-up or in override control. Developments in control methods are always supplemented by easily repeated numerical examples. Academics doing control-related research in electronics, mechanics, or mechatronics and engineers working in the process industries will find this book an extremely useful overview of systematic windup prevention for all kinds of systems. It also has valuable insights to offer the graduate student of control.