拖拉机线控液压转向系统的双通道PID控制仿真与试验  

Simulation and experiment of dual channel PID control for hydraulic steerby-wire system of tractor

作　　者：鲁植雄[1] 龚佳慧 鲁杨[1] 刁秀永[1] 程准[1] 姜春霞[1] 周晶[1] 

机构地区：[1]南京农业大学工学院,南京210031

出　　处：《农业工程学报》2016年第6期101-106,共6页Transactions of the Chinese Society of Agricultural Engineering

基　　金：江苏省科技支撑计划资金项目(BE2012384)

摘　　要：拖拉机线控液压转向系统采用的单杆液压缸具有非对称性,为了提高转向系统的控制精度,提出了双通道PID(proportional integral derivative)控制方法,对液压缸活塞杆伸出和缩回的运动进行分通道控制。基于Sim Hydraulics模块建立线控液压转向系统的物理模型,对转向轮的跟随响应、阶跃响应进行仿真试验;同时搭建了线控液压转向系统试验台,进行台架试验,从而分析双通道PID控制对转向系统的影响。仿真试验得出双通道PID控制的跟随误差为0.473°、响应时间为0.273 s,且左、右转向跟随误差基本一致,均优于单通道PID控制,台架试验结果与仿真试验的效果一致。结果表明,线控液压转向系统在双通道PID控制下响应快,跟随误差更小,具有良好的跟随性和较高的控制精度。The hydraulic steering-by-wire system abandons the mechanical connection between hand-wheel and front steering wheels, and thus the driver′ s intent is delivered via electrical signal. The actuator of hydraulic steering-by-wire system is the hydraulic cylinder. ECU（electronic control unit） generates the corresponding electric current to control the opening of electro-hydraulic proportional servo valve after receiving the steering signal, which correspondingly leads to the displacement of steering hydraulic cylinder. The displacement direction determines the steering direction and the magnitude determines the steering angle. At present, asymmetric hydraulic cylinders are mostly adopted. However, due to the piston areas are varied as the piston rod moves in different directions, even if the opening of electro-hydraulic proportional servo valve and the pressure are fixed, the displacements of the piston rod vary under stretch and retracting condition. Combining hydraulic steering-by-wire system with asymmetric hydraulic cylinder, we know that accuracy adjustment of steering is essentially the adjustment of the hydraulic cylinder piston rod′s displacement on the left or right side. Therefore, the traditional PID（proportional integral derivative） control of hydraulic steering-by-wire system is not efficient for precise control of steering angle. Considering the error is either positive or negative in steering angel, to improve control accuracy, the hydraulic cylinder can be regarded as different hydraulic cylinders with different piston areas working alternately. This paper presented the idea of dual-channel PID control, in which way the 2 hydraulic cylinders（positive or negative error） used different channels with different PID parameter values. The characteristic of dual-channel control was that when the errors, whose magnitudes were same and positivity and negativity were different, were adjusted with different PID values, the control current of electro-hydraulic proportional servo valves was not sa

关 键 词：农业机械 拖拉机 线控液压转向 PID控制 双通道 SIM Hydraulics 

分 类 号：TP23[自动化与计算机技术—检测技术与自动化装置] S24[自动化与计算机技术—控制科学与工程]