Physical Modeling of a Nonlinear Semi-Active Vehicle Damper

In this paper a physical model of a continuously variable semi-active dual-tube damper, which will be used for controller design for a mechatronic suspension system, is presented. The model of the passive damper is extended with an electro-/fluid-mechanical model, which captures the continuously variable damping effects by two independently adjustable electromagnetic valves. The unknown physical model parameters are estimated with a genetic algorithm and a gradient-based optimization method to match measurement data. The fluid-dynamic effects are derived from the compressibility of the oil, geometry and the adiabatic compression of the gas. The electrical model of the damper's power unit also incorporates an internal current controller. The validity of the semi-active model is demonstrated for different currents by comparing the simulation results with measurement data from a test rig.