基于显式模型预测控制的轮毂驱动电动车垂向振动研究

Vertical vibration of hub motor driven electric vehicle based on EMPC

针对轮毂驱动电动车非簧载质量增大而引起的行驶平顺性和操纵稳定性恶化问题,提出了基于显式模型预测控制(EMPC)理论的主动悬架控制方法。建立由刚性环轮胎模型和空气悬架模型组成的四自由度系统模型,并确定车辆平顺性、稳定性和电机性能多目标函数及约束条件;基于多参数二次规划理论,将隐式模型预测控制系统转换为与之对应的显式多面体分段仿射(PPWA)系统,离线求解状态变量间的最优控制律,并运用参数分区上的显式控制律求得最优主动力。仿真结果表明:相较于被动悬架和运用天棚控制策略的主动悬架,基于EMPC理论控制的主动悬架对车身垂向加速度、轮胎动载荷和轮毂电机偏心距均方根值提升效果明显,改善了轮毂电机驱动电动车的行驶平顺性、操纵稳定性和电机性能。

Here,aiming at deterioration of ride comfort and handling stability caused due to increase in unsprung mass of hub driven electric vehicle,an active suspension control method based on the explicit model predictive control(EMPC)theory was proposed.A 4-DOF system model composed of rigid ring tire model and air suspension model was established,and the function of multi-objective including vehicle ride comfort,stability and motor performance and constraint conditions were determined.Based on the multi-parameter quadratic programming theory,the implicit model predictive control system was converted into the corresponding explicit polyhedral piece-wise affine(PPWA)system,the optimal control law of state variables was solved off-line,and the optimal active forces were obtained by using the explicit control law on parametric partitions.The simulation results showed that compared with the passive suspension and the active suspension using sky-hook control strategy,the active suspension based on EMPC theory has an obvious effect on improving RMS values of vehicle body vertical acceleration,tire dynamic load and hub motor eccentricity;it improves the ride comfort,handling stability and motor performance of hub motor driven electric vehicles.