受饱和约束的车辆转向非线性鲁棒模糊分布控制

Nonlinear robust fuzzy distributed control of vehicle steering with saturation constraint

针对极限状态下车辆转向非线性和执行器饱和问题,研究主动前轮转向(active front steering, AFS)和直接横摆力矩控制(direct yaw-moment control, DYC)对横摆-侧倾稳定的集成控制。采用Takagi-Sugeon(T-S)方法建立车辆3自由度横摆侧倾模型,结合模糊观测器实时获取模型动态参数。为准确反映车辆转向稳态过程,在T-S框架下建立改进横摆理想参考模型。考虑到极限转向对前轮侧偏特性的影响,构建T-S框架下主动前轮输入的动态饱和阈值。引入松弛因子提高AFS和DYC的执行器利用率,将反馈输入的饱和影响作为有界扰动进行控制。基于分布补偿结构设计状态反馈模糊分布控制器(parallel distributed compensation-TS,PDC-TS),采用范数有界的侧翻稳定阈作为侧倾性能约束,将车辆横摆-侧倾稳定性的H;性能转换为线性矩阵不等式(linear matrix inequalities, LMIs)凸优化问题。最后联合Trucksim-MATLAB/Labview软件进行控制仿真和硬件在环验证,结果表明,PDC-TS方法对强非线性转向过程的控制更加准确,执行器能力利用更充分,并在输入饱和约束下保持控制稳定性。

Aiming at nonlinear steering and actuator saturation problems in extreme state, the integrated control of active front steering(AFS) and direct yaw-moment control(DYC) of yaw-roll stability was studied. A 3 DOF yaw-roll vehicle model was established with the Takagi-Sugeon(T-S) method. Dynamic parameters of the model were obtained through a fuzzy observer. A novel yaw ideal reference model was conducted under the T-S framework, accurately reflecting vehicle steady-state during steering. The dynamic saturation threshold of active front steering was constructed under the T-S framework, considering the effect of extreme steering on sideslip characteristics of front wheels. A relaxation factor was introduced to improve the actuator of AFS and DYC efficiency, and saturation deviation of feedback control input was controlled as a bounded disturbance. A state feedback fuzzy controller PDC-TS(parallel distributed compensation-TS) was designed based on a PDC scheme, with the norm-bounded rollover stability threshold adopted as rollover performance constraint, and optimal H;performance control was derived in terms of an linear matrix inequalities(LMIs) convex optimization problem for vehicle yaw-roll stability. Finally, control simulation and hardware in loop simulation for the controller was constructed with TruckSim-MATLAB/Labview softwares. The obtained results show that the PDC-TS method is more precisely to control strong nonlinearity of vehicle during steering process, and actuator implementing is more efficiently, and stability is always maintained with saturation input.