Rule-based control of a semi-active suspension system for road holding using limited sensor information: design and experiments

This paper presents a design of a rule-based controller for a semi-active suspension system that improves the vehicle road holding behaviour. This behaviour is quantified by the evaluation of the dynamic tire deflection at each of the vehicle's wheels. The control rule switches based on the product of the unsprung mass- and suspension deflection velocity and the excitation frequency. To determine how much the dynamic tire deformation is improved, the controller is compared to multiple passive suspension configurations as well as existing semi-active suspension controllers. The proposed controller is capable of achieving a minimal tire deformation over the entire frequency range of interest. Additionally, experiments are performed on a test vehicle which is equipped with semi-active dampers and the designed controller. In the experiments, the unsprung mass acceleration is measured since the tire deflection is impossible to measure in practice. A fixed trajectory has been driven for the controlled system and for a set of passive suspension configurations, a reduction of up to 11% of the root mean square (RMS) unsprung acceleration is seen compared to the best passive setup.