Pseudo-Derivative Feedback Control

The extensive presence of simple PID controllers all over the process and manufacturing industries attests to their continuing and lasting effectiveness in dealing with all but the most complex and demanding industrial control problem. Problems do arise with PID controllers however. In particular high frequency sensor noise problems can become severe in some applications, due to the presense of the D component of the PID controller. By altering the controller structure slightly, it is possible to obtain the attendant benefits of derivative action, without taking the derivative of the error function. This is called pseudo-derivative feedback and overcomes many of the major problems of derivative control. The structure and ramifications of this scheme is examined here, for both multivariable and single input single output systems.