Two adaptive root-locus control schemes for processes with time delays have been developed. The control design methodologies are based on classical feedback control and Smith predictor structures with simple pole placement. The overall behaviour of both control systems is adapted along the root loci of the system in each control horizon. Since the Smith predictor structure includes time delay compensation, the tuning gain can be enlarged to improve the performance of the control system. The optimal tuning gain is repeatedly updated by an optimization technique when the estimated model is confirmed. A comparison with simplified model predictive control (SMPC) is also given. SMPC in SISO systems is a special case of the proposed control laws.
KEY WORDS Adaptive control Smith predictor Root loci Pole placement
Time delay systems Self-tuning controllers overall transfer function Gd ( z ) is tedious because finding an implementable G d ( z ) requires a trial-and-error method based on computer simulations. l 3 The other drawback of the basic pole assignment algorithm is its non-optimality. l4 Therefore a guideline for selecting the desired poles of the closed-loop system and optimizing the basic pole placement algorithm is needed.
In this paper the overall behaviour of the control system is assigned by the root-locus