Adaptive Control of Active Suspension Systems
Introduction
The flexibility of (semi-)active suspension hardware can be fully exploited if an adaptive controller is designed that changes its parametrization depending on the current driving situation of the vehicle. Thus the suspension can be stiffened if the spring tends to hit its limit or a more safety oriented controller paramterization can be chosen if the vehicle moves over rough terrain. Otherwise a controller parametrization that focusses on the maximization of ride comfort can be chosen.
The goal of the project is to design adaptive suspension controllers for different hardware configurations of active suspension systems in order to ease the conflicting objectives of a suspension system as good as possible with reasonable power consumption of the actuators.
Adaptive Controller Structure
A switching controller structure based on linear quadratic optimal regulators combined with a Kalman Filter as well as linear parameter variant (LPV) control techniques are used for controller design. The switching between the controllers depends on the dynamic wheel load estimation and the suspension deflection measurement. The control concept is validated using simulations of the nonlinear quarter-vehicle model as well as measurements at the high bandwidth quadricycle testrig. The excitation signals are gained by measurements from real road profiles.
The performance benefit validated by measurements is in the range of 30% reduction of the chassis accelerations RMS value while keeping all given limits for ride safety and maximum suspension deflection.
Exemplary Publications
G. Koch, O. Fritsch, B. Lohmann, "Potential of Low Bandwidth Active Suspension Control with Continuously Variable Damper", 17th IFAC World Congress, Seoul, South Korea, 07/2008
G. Koch, K. J. Diepold, B. Lohmann, "Multi-Objective Road Adaptive Control of an Active Suspension System", The 9th International Conference on Motion and Vibration Control (MOVIC 2008), Munich, 09/2008 and in: Motion and Vibration Control - Selected Papers from MOVIC 2008, H. Ulbrich and L. Ginzinger (ed.), pp. 189 - 200, Springer Verlag, Berlin, 2008
G. Koch, E. Pellegrini, B. Lohmann, "Zustandsadaptive Regelung eines aktiven Fahrwerks - Entwurf und Implementierung am Viertelfahrzeugprüfstand", Presented at the 6. Paderborner Workshop "Entwurf mechatronischer Systeme", Paderborn, 04/2009 and in: Entwurf mechatronischer Systeme, J. Gausemeier, F. Rammig, W. Schäfer, A. Trächtler (ed.), pp. 43 - 56, Heinz Nixdorf Institut Verlagsschriftenreihe, Band 250, 2009
O. Fritsch, G. Koch, B. Lohmann, "Deflection Adaptive LPV Control of an Active Suspension System", Proceedings of the IEEE European Control Conference (ECC09), Budapest, Hungary, 08/2009
G. Koch, "Wheel load adaptive control of an active quadricycle suspension system", In: Methoden und Anwendungen der Regelungstechnik. Erlangen-Münchener Workshops 2007 und 2008, B. Lohmann and G. Roppenecker (ed.), pp. 95 - 107, Shaker-Verlag, 2009