Minimizing the Effect of Disturbances Acting on Control Systems

This paper presents an analytical method for minimizing the effect of external undesirable disturbances acting on a closed loop control system. The approach used in this method is to design an optimal time-variant gain controller, in order to improve the dynamic performance of a closed loop control system, with the existence of external undesirable disturbances acting on the system states. The values of the gain computed at any switching instant of time is a function of the input signal to the system and the instantaneous values of the system states which are implicitly a function of the disturbances acting on them with respect to time. The measure of optimality is taken to be the minimum value of the Integral of Squared Error (ISE) criteria, computed between the output of the controlled system and the desired set-value. A third order servomechanism system, with the existence of different disturbance values effect, is taken as an example to show the usefulness and powerfulness of this technique.