文章分析了电动助力转向(electric power steering, EPS)系统各部分的动力学模型,并由此搭建了其Simulink仿真模型;对于时变性、非线性较强的EPS系统,采用了单神经元自适应PIn(single neuron self-a-daptive PID, SNPID)控制算法;针对一般助力特性曲线下EPS系统动态响应特性较差的问题,提出了在转矩传感器检测的转矩之中加入相位超前补偿、应对路面冲击的转矩微分补偿、减轻转向系统摩擦对系统影响的摩擦补偿、改善快速转向或换向时电机助力的迟钝和驾驶员“顿挫”感的惯性及阻尼补偿;并在上述补偿的基础上,针对原地撒手抖动问题提出了基于转矩变化率的助力死区增大控制方案。仿真和实车试验结果表明,加入补偿控制的EPS助力策略的动态响应特性和转向轻便性均得到了改善。
The dynamic models of electric power steering(EPS) system components are analyzed, with which the simulation model based on Simulink is established. For EPS system with stronger time-var- ying and nonlinear characteristics, the single neuron self-adaptive PID(SNPID) control algorithm is a- dopted. Concerning the poor dynamic response characteristic of the EPS system under general assist characteristic curve, compensatory torques are added to the detected torque of the torque sensor inclu- ding the phase-lead compensation, the differential compensation which is used to deal with road shocks, the friction compensation which is used to reduce the impact on system from the friction of steering system and the inertia and damping compensation which is used to improve the insensitive performance of motor and the lock feeling of driver when fast turning or reversing. On the basis of the compensation above, in order to solve jitter in situ after relinquishing hands on steering wheel, a con- trol scheme of enlarging the assist dead zone based on rate of torque change is put forward. The re- sults of simulation and vehicle experiment show that the dynamic response characteristic is improved and the steering behavior is easier when the compensation control is contained in EPS assistance strategy.