Model-based Control of Electrical Actuators with Nonlinear Dynamics

Conference: IKMT 2015 - 10. ETG/GMM-Fachtagung Innovative Klein- und Mikroantriebstechnik
09/14/2015 - 09/15/2015 at Köln, Deutschland

Proceedings: ETG-Fb. 146: IKMT 2015

Pages: 6Language: englishTyp: PDF

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Grotjahn, Martin (University of Applied Sciences Hannover, Germany)
Luck, Bennet; Feldt, Matthias (IAV GmbH, Gifhorn, Germany)

Modern drive systems often show strong time-varying and nonlinear effects. Commonly used linear controllers, however, are not able to systematically master these effects, which results in limited accuracy and dynamics of the closed-loop system. Distinct improvements can be achieved by nonlinear control methods. In this paper, such methods are presented and compared by application to an highly nonlinear automotive actuator. The first approach consists of a state controller with model-based feedforward control and disturbance observer. The approach is based on dividing the model into linear dynamics and static nonlinearities. Compensating the static nonlinearity leads to a predominantly linear control problem. The feedback of an observed disturbance yields an approximate deletion of all model simplifications and neglected influences. As second approach, Exact Linearisation (EL) is applied. It is combined with a joint state and parameter estimation by an Extended Kalman-Filter (EKF) to overcome its major drawback, the sensitivity with respect to model uncertainties. Both approaches are based on a nonlinear plant model which is automatically identified. Thus, the complete approaches are also applicable to other drives with nonlinear dynamics. The control structures are implemented in a real-time environment using rapid-prototyping hardware. Performance and robustness are confirmed by extensive tests in a climatic chamber including worst case scenarios.