H∞ Observer for Damper Force in a Semi-Active Suspension

An H ∞ observer for the Semi-Active (SA) force of an Electro-Rheological (ER) damper in a Quarter of Vehicle (QoV) model is proposed. This robust observer is designed in the H ∞ framework to minimize the effect of the unknown road disturbance on the force estimation and includes the damper nonlinearities and its dynamic behavior. Simulation and experimental rig tests results using a 1/5 scale car using easily accessible measurements for the observer, such as acceleration sensors, which are relatively cheap and easy to implement in a real environment. The estimated damper force could be used in a state feedback control strategy to improve comfort and road holding performance of a vehicle with a reduced number of sensors.