Research Of Synthetic Robust Control Of Vehicle Active Suspension System And Electrical Power Steering

Integrated mathematical models are set up for a full vehicle suspension system with seven degrees of freedom and electrical power steering, meanwhile, mathematical models are set up for a half vehicle suspension system with four degrees of freedom. Robust controllers, based on robust control theory and game theory, are devised. Firstly, Multi-objective optimal control law is devised and applied to the active suspension system of 4 degree-of-freedom half-vehicle model. Norm H∞ is selected as the evaluated index of robust performance. Norm H2 is selected as the evaluated index of LQG. The multi-channel multi-objective mixed H2/H∞ controller is devised to balance the vehicle handling stability and the ride comfort performance. Secondly, the mixed H2/ H∞ control is formulated as a game problem of incomplete information, a suboptimal 2x2 non-zero game model is constructed, where two channels are chose as players and H2 and H∞ control are pure strategies, and an algorithm for mixed H2/ H∞ control, which is based on the Nash's bargaining theory, is derived to achieve the Nash equilibrium point. Finally, handling stability, ride comfort and steering handiness are related with vehicle suspension system and electrical power steering. H∞ robust controller is devised for the integrated mathematical models. Computer simulations with Matlab6.1 demonstrate that H2/H∞ output feedback controller of the active suspension system, based on Nash equilibrium point, achieves a good balance between robust stability and suspension performance. H∞ robust controller for integrated models of a full vehicle suspension system and electrical power steering attains optimal handling stability and ride comfort and improves handling sensitivity and steering handiness.