高地隙自走式喷雾机多模式液压转向系统设计与试验

为提高高地隙喷雾机的机动性能和作业效率、减少压苗损伤,设计了基于PID控制算法的多模式液压转向系统。采用AMESim软件建立了机械-液压系统耦合模型,采用序列二次组合优化算法确定PID参数的最佳组合,并对不同负载力和负载质量下的系统控制精度进行仿真。仿真结果表明:当比例系数为19.087、积分时间常数为2.008、微分时间常数为0.032时,系统误差最小;前后液压缸负载力差值或负载质量变大,位移误差随之增大,最大误差为-2.18 mm,PID控制算法和压力补偿系统确保了变载荷下系统的控制精度。研制了多模式液压转向系统,进行了坡地和田间转向试验,田间试验时,前后轮转向液压缸之间平均位移误差为4.07 mm,最大误差为-17.59 mm;在坡度15°的路面上,前、后轮转向液压缸之间的平均位移误差为4.89 mm,最大误差为21.34 mm;在前轮转向和四轮转向模式下,不同外前轮转向角田间转向半径的实测值略均大于理论值,误差率均小于4.0%。试验结果验证了所设计的转向系统具有较高的控制精度和稳定性。

Design and Experiment of Multi-mode Hydraulic Steering System of High Clearance Self-propelled Sprayer

A multi-mode hydraulic steering system based on PID control algorithm was designed to improve the maneuverability and efficiency of high clearance sprayer. The new technical scheme of the hydraulic system was proposed. The coupling model of mechanical-hydraulic system was established in AMESim software, and the optimal combination of PID parameters was determined by sequential quadratic combination optimization algorithm. And then the control precision of the system was simulated under different load force and load mass. The simulation results showed that the controlling precision was superior when the proportional coefficient was 19.087, the integral time constant was 2.008, and the differential time constant was 0.032. When the loading force difference or the load mass of the front and rear hydraulic cylinders was increased, the displacement error was increased, and the maximum error was only -2.18mm, which meant that the PID control algorithm and pressure compensation system can ensure the control accuracy. The multi-mode hydraulic steering system was developed for sloping road and field experiment. For the field experiment, the average displacement error between steering cylinders of front and rear wheels was 4.07mm, and the maximum displacement error was -17.59mm. For the sloping road experiment, the average displacement error between steering hydraulic cylinders of front and rear wheels was 4.89mm, and the maximum displacement error was 21.34mm. The measured value of steering radius at different steering angles was a little greater than the theoretical value for both steering modes and the error rate was less than 4.0%. The experimental results showed that the designed steering system had superior control accuracy and stability.