Minimum-time predictive control of a servo engine with deadzone

This paper presents a hybrid approach to cope with deadzone types of nonlinearities, which are often present in many mechanical systems. If the effect of the deadzone is not directly considered in the control design, it may cause unwanted performance loss and may lead to chattering around the deadzone limits. It will be shown that the deadzone can be naturally modeled using piecewise affine (PWA) models, and that such models are suitable for design of control policies which take the deadzone behavior into account. In this paper, the controller design scheme is based on the so-called minimum-time principle. It is shown that such design task can be formulated as a model predictive control (MPC) problem, where the solution takes a form of a look-up table. It will be presented that such table can be evaluated in real-time, hence allowing to apply the concept of MPC to devices with very fast sampling rates. Experimental results show that the MPC controller based on a PWA description of the deadzone nonlinearity meets the desired goals. (C) 2009 Elsevier Ltd. All rights reserved.