Autotuning principles for time-delay systems

Abstract

This paper presents a set of single input - output (SISO) principles for tuning of continuous-time controllers used in autotuning schemes. The emphasis of designed autotuners is laid to SISO systems with time delay. Autotuners represent a combination of relay feedback identification and some control design method. In this contribution, models with up to three parameters are estimated by means of a single asymmetrical relay experiment. Then a stable low order transfer function with a time delay term is identified by a relay experiment. Controller parameters are analytically derived from general solutions of Diophantine equations in the ring of proper and stable rational functions RPS. The generalization for a two degree of freedom (2DOF) control structure is performed. This approach covers a generalization of PID controllers and enables to define a scalar positive parameter for further tuning of the control performance. The analytical simple rule is derived for aperiodic control response and the scalar tuning parameter m7gt;0. Autotuning principles of this contribution are applied to SISO systems with delays. Moreover, the Smith predictor scheme is applied for systems with a time delay term. The simulations are performed in the Matlab environment and a toolbox for automatic design and simulation was developed.