Integrated Control Of Active Front Control And Direct Yaw Moment And Implementation Based On FPGA

As the vehicle active safety problem has been paid more and more attention, thesimple superposition between the electric control systems can not meet the demand, inte-grated control has became the trend of electronic control system research in recent years.In this paper, in order to further improve the vehicle lateral stability, active front wheelsteering and direct yaw moment have been aimed at for integrated control. Because whenthe traditional ESP system based on direct yawing moment control(DYC) does the brakeintervention, it will produce braking efect. Therefore，it will make the drivers obviouslyfeel the declining speed and influence the driving comfort. While AFS can detect activesteering intervention and do not afect the longitudinal dynamics. So, the integratedcontrol of active front wheel steering and direct yaw moment can not only improve thestability of the vehicle performance, but also reduce the influence of longitudinal dynamicsand improve the vehicle driving comfort.On the basis of the above problems, a nonlinear fraction tire model is used in theprocess of establishing simplifed vehicle model, and the front and rear tire side-slip anglewhich can response the stability of the vehicle are selected as the system state variables.It will lay a foundation for the design of the integrated controller. In the study of thecontroller design, a hierarchical supervisory control strategy is adopted. Considering thesafety and physical constraints of actuators, control problems are transformed into non-linear constraint problem with the application of the nonlinear model predictive control.The external yaw moment and front wheel steering can be obtained by solving optimiza-tion problems. Then, the distribution principle of single wheel is chose. According to thestate of the vehicle, the additional yaw moment can be distributed into brake force.To test the integrated controller designed in this paper, a variety of simulation work-ing conditions are set. The function, properties and advantages of controller are analyzedfrom various perspectives. At the same time, the influences of tire-road friction coefcientand longitudinal velocity for vehicle lateral stability have been analyzed.At last, this paper proposes a hardware implementation scheme to improve the online calculation performance of nonlinear model predictive control. Due to the confgurabilityand parallel computing characteristic of FPGA, online computing performance of NM-PC has been improved from the perspective of hardware implementation. The controllerfnally downloads to the FPGA board based on the FPGA development process. Com-bined with xPC target, simulation validation results can explain the realtime efect ofthe integrated controller, the hardware implementation scheme has better computationalperformance.