Set Point Weighted Pid Controllers For Unstable Systems

Abstract

A systematic method is given for selection of the set point weighting parameter (b) in PI/PID controllers for unstable first-order plus time delay systems. The method is based on minimizing the integral square error (ISE) for a servo problem. The present work also extends the method of Chidambaram (2000a, 2000b) by minimizing overshoot for the cases of damping coefficient, ζ > 1 and ζ = 1. The responses of PID controllers without and with the set point weighting are compared. Simulation results are also given for an FOPTD transfer function system, for a higher order transfer function model, and on a nonlinear chemical reactor problem. The present method gives an improved performance.

Key Words:

• Set point weight
• PID controller
• Optimization
• ISE
• Overshoot
• Unstable system