四轮独立电驱动高地隙喷雾机辅助转向系统设计与试验

针对四轮独立电驱动高地隙喷雾机因轮毂电机控制器遇到较大扰动无法及时响应而导致的转向不稳定问题,该研究提出了一种液压辅助转向方法。通过对四轮独立电驱动高地隙喷雾机的自转向底盘结构原理的分析,设计了液压辅助转向系统,在此基础上建立了简化二自由度车辆转向模型,用于对辅助转向系统转角控制进行分析,并通过仿真分析和试验验证自转向和辅助转向协调控制性能。四轮电驱动喷雾机分别在自转向系统单独作业以及自转向系统和辅助转向系统协同作业的工况下,以1 m/s的速度分别进行了坡度为15°的下坡转向对比试验和水田转向对比试验。试验结果表明:在下坡试验中,单独自转向系统作业的最大跟踪偏差为6.1°,自转向和辅助转向协同作业的最大跟踪偏差为0.9°;水田试验中,单独自转向系统作业的最大跟踪偏差为10.3°,自转向和辅助转向协同作业的最大跟踪偏差为1.5°。研究结果表明该文所设计的液压辅助转向系统具有可行性和较好的稳定性,能够满足实际作业需求。

Design and experiment of the auxiliary steering system for a four-wheel independent electrically driven high clearance sprayer

Aiming at the unstable steering of a four-wheel independent electrically driven high clearance sprayer due to the failure of the hub motor controller to respond to a large disturbance, an auxiliary steering method based on electrically controlled hydraulic pressure was proposed. Firstly, the structure and steering principle of the self-steering chassis of the four-wheel independent electrically driven highland gap sprayer were briefly introduced. Secondly, the realization method of the hydraulic assisted steering system was described, including the establishment of the steering resistance moment calculation model, and the analysis of the steering resistance moment required by the wheels under rolling and sliding conditions. The upper limit of the steering resistance moment can be calculated when the two wheels fail turning. Thirdly, based on the structural characteristics of the self-steering chassis, the kinematics model of the hydraulic auxiliary steering was established, the relevant parameters of the important components of the hydraulic system were calculated, the installation position of the hydraulic cylinder was determined, and the key components of the hydraulic system were selected. Finally, the simulation and experiment were carried out to verify the performance of coordinated control of auto steering and auxiliary steering. In the simulation test, the independent operation of self-steering, the independent operation of auxiliary steering, and the collaborative operation of the self-steering and auxiliary steering of the sprayer were simulated and adjusted to make the angle tracking trajectory of the self-steering and the auxiliary steering as consistent as possible. The simulation results showed that, self-steering alone, auxiliary steering alone, and coordinated self-steering and auxiliary steering could all track to the target angle by about 1.8 s. The response of the self-steering is relatively slow in the early stage, but it is a little faster than the auxiliary steering when tracking the target Aangle in the later stage. The auxiliary steering has a slight overshoot after tracking the target Aangle and keeps this slight error in the later stage. Since the self-steering and auxiliary work together has faster response performance than the first two separate operating systems, they are more stable when they reach the target angle. Under the working conditions of independent operation of the self-steering system and cooperative operation of the self-steering system and auxiliary steering system, the comparison tests of downhill and paddy field with a gradient of 15° were carried out at a speed of 1 m/s respectively. The test results showed that in the downhill test, the maximum tracking deviation of the independent auto-steering system operation was 6.1°, and the maximum tracking deviation of the co-operation of auto-steering and auxiliary steering was 0.9°. In the paddy field test, the maximum tracking deviation of the independent auto-steering system operation was 10.3°, and the maximum tracking deviation of the co-operation of auto-steering and auxiliary steering was 1.5°. The experimental results verify the feasibility and stability of the proposed hydraulic auxiliary steering system. The system has good test performance and can meet the actual operation requirements.