Performance indices in evolutionary CACSD automation with application to batch PID generation

This paper addresses the issue of transforming CACSD to `computer-automated control system design´, the fundamental step towards which is to devise simple performance indices that can reflect all time and frequency-domain requirements under constraints. The merit and selectivity of five commonly used indices are hence analysed and assessed against design specifications, together with five new indices proposed. It is shown that hybridising indices can offer selectivity for damping ratios ranging from 0.5 to 1.0 (and extending to the infinity) for the overall closed-loop system. Using the ITAE index, evolutionary computation is applied to enable batch PID design automation. This leads to multiple optimal controllers for various time-constant ratios, satisfying both time and frequency domain requirements, including robust stability and low maximum sensitivity