Mixed H2/H∞ control for electromagnetic active suspension

This paper presents a mixed H2/H∞control strategy under main/ torque-tracking loop structure for an electromagnetic active suspension. First, the modelling of the electromagnetic actuator is conducted. Then, the main/torque-tracking loop structure is proposed, in which the main loop calculates the demand torque for electromagnetic actuators based on a full-car suspension model, using mixed H2/H∞ control strategy. Body acceleration, suspension working space, dynamic tyre displacement and demand torque are considered as H2 performance indices, and suspension working space and demand torque are also H∞ performance indices. The torque-tracking loop applies hysteresis current control for electromagnetic actuators to track the demand torque calculated by the main loop. Finally, simulation results demonstrate that the designed controller can greatly improve ride comfort and is less conservative than H∞ controller. The effects of parameter perturbations and dynamic response of suspension system are also studied, indicating that good robustness can be achieved.