PID control system fed back along with squares of control error and its derivative-optimum design of nonlinear PID controller

A nonlinear PID controller has been proposed to improve the quality of control, by attaching the squares of control error and its derivative to the standard PID controller. Optimum control parameters are evaluated at time domain, by direct numerical simulation for PID control system and by direct numerical optimization algorithm, that has ability to find global optimum among local optimums. Robustness of the nonlinear PID controller has been checked for five control parameters and three process model parameters, on graphical pattern of the control error levels around the optimum point. Proposed nonlinear PID controller shows better quality of control than the standard PID controller.