Vehicle suspension and steering nonlinear integrated system coordinated control based on human-vehicle function allocation

The coupled dynamics between the vehicle chassis suspension system and electrical power steering system(EPS) is analyzed, to establish the full-vehicle nonlinear model, EPS model, tire model and road input model. The tire’s complex nonlinear model is approximated by utilizing the least square method, so as to obtain the integrated system model with the 22-order. To simplify the nonlinear controller design, the nonlinear dynamics model is separated into two parts of nonlinear part and linear part. The state feedback optimal controller is designed for the linear part model, and the linear compensator based on the deviation separation is for the nonlinear part model, which can ensure the closed-loop control system is exponential asymptotic stability at the equilibrium point. The human-vehicle function allocation is adopted to adjust the two subsystems’ output weights based on the fuzzy rules, to restrain the suspension roll motion and adaptively compensating driver’s steering torque. The considerable simulations are carried out, and the results demonstrate that the suspension and EPS coordinated control system by applying bilinear control can obtain better performance than another nonlinear control method; the human-vehicle function allocation can further improve the vehicle whole-region control performance.