Equilibrium optimiser tuned frequency-shifted internal model control proportional-derivative decoupled dual-loop design for industrial plants followed by experimental validation

Abstract

Integrating and unstable processes require rugged control demand by virtue of their non-self-regulation character. The occurrence of system poles located at the origin and on the right half of the complex frequency plane causes instability in an open-loop configuration. When these processes proceed with dead time, it demands more sophisticated control requirements. Therefore, binal-loop control schemes are recommended over single-loop controller schemes. For plants with prevalent unstable and integrating dynamics and dead time, a novel modified inferred internal model control-proportional derivative decoupled binal-loop control system is suggested. The inner-loop is controlled by the stabilising proportional derivative controller with Routh–Hurwitz stability constraints. The outer-loop contains an inferred internal model controller for reference-point tracking. The equilibrium optimiser is then used to minimise the integral squared error by tuning the inner and outer-loop controller settings in the confined search space. The suggested strategy delivers appreciable enhancement in the quantitative performance measures as compared to some of the contemporary control techniques. The effect of time-varying disturbance and robust stability analysis is also presented. Finally, utilising a magnetic levitation laboratory setup, the suggested method is experimentally verified using the hardware-in-loop method.