Robust H∞ control design of an electromagnetic actuated active suspension considering the structure non-linearity

Abstract

Electromagnetic actuated active suspension (EAAS) benefits energy harvesting while providing active control. However, the inertia of the actuator introduces an equivalent mass coupled with the sprung and unsprung mass. In addition, the specific structure of the suspension features structure non-linearity, which results in the perturbation of the equivalent mass of the actuator, the variation of the transmission ratio of the actuator output torque to the actuator force at the wheel side and an extra force to be compensated with. A dynamic model of active control considering the equivalent mass and the structure non-linearity is proposed. Based on a gearbox type EAAS, respective non-linearity is studied. For multi-objective optimization, a robust controller is designed with proper weighting functions. A virtual prototype of the EAAS is built and simulated with a bump/pothole and random excitation road profiles. Results show that neglecting the structure non-linearity effects influences the accuracy of active control. The investigation of this paper provides a fundamental methodology for the control design of actual applications of EAASs.