An Application of Adaptive Scheme to Fluid Level Control

This paper presents an application of an adaptive control scheme to the problem of controlling fluid level in a coupled tanks apparatus. The study is intended to explore several practical issues arising in the use of adaptive control to realistic processes. The controlled system exhibits different time constants for filling and emptying, unmodelled static nonlinearity, unmodelled time delay, unmodelled high frequency lag and unmodelled d.c. offset. The control scheme has a PI structure and is designed using a certainty equivalence form of pole-assignment. The adaptive controller is shown to perform satisfactorily in the presence of these practical difficulties, and has characteristics which are superior to those obtained from a well-tuned PID controller.