MR-SAS And EPS Variable Universe Fuzzy PID Integrated Control

With the development of control theory and its application, the vehicle chassis control technology has become intelligent gradually, and which has been to the development of integrated control. Nowadays, the control technology of vehicle chassis key subsystem have been developed relatively mature, and its separate application in the vehicle has a better effect. But there are some coupling between the subsystems, such as the semi-active suspension (SAS) and the electric power steering (EPS) are all related to the vehicle ride smoothness and handling stability, both have obvious coupling relationship. So the relationship between the SAS and EPS should be coordinated necessarily, and to have integrated control. For the further realize the integrated control, an in-depth study of integrated control of EPS and SAS applied magneto-rheological damper has been conducted in this paper.Firstly, the working mode of MR damper was studied, and its dynamic model was derived, and then the simulation analysis was conducted. In order to verify its application effect in suspension, the MR damper was applied to1/4vehicle suspension model, and considering its nonlinear characteristic, after accuracy linearization the model by the differential geometry theory, the LQG controller of linear system was designed, and the weighted coefficient of LQG controller was determined by the the analytic hierarchy process. The simulation result show that the MR damper can satisfy the vehicle demand, preparation for the work in the full vehicle suspension.Secondly, the fuzzy control and PID control theory and design method was studied. Considering the problem of difficult adaptive of fuzzy controller, the variable universe theory based on fuzzy inference was introduced. Avoid the previous subjective choice of universe adjusting function. Considering the superiority of compound control, the tandem type and parallel type variable universe fuzzy PID controller was studied. Comprehensive selected switch parallel type variable universe fuzzy PID control based on trapezoidal membership function. Prepare for the following application to the whole vehicle integrated control.Thirdly, the dynamic modeling of integrated system. In order to maximize the performance of suspension, and verified the effectiveness of variable universe fuzzy controller in integrated control,1/2vehicle dynamic model of MR-SAS in steering condition based on wheelbase preview was established. And then the integrated system dynamic model of full vehicle model in steering condition, EPS model, tire model road input model was established. And the effect of MR-SAS and EPS on body posture was analyzed.Last, the full vehicle variable universe fuzzy PID integrated controller of MR-SAS and EPS was designed, variable universe fuzzy PID integrated control was applied to suspension system, and fuzzy PD control was applied to EPS, and the variable universe fuzzy coordinated controller was designed to coordinated the relationship of MR-SAS and EPS. And the random road input and steering wheel angle step input simulation experiment was carried on. The simulation results show that compared with the passive system and separate control, the integrated control system has obvious superiority.