Improvement of Working Quality of Trailing Implements by Hitching Position Control

本课题的研究目标是实现挂车技术要求驾驶中的轻松驾驶和自主行驶。拖车行驶中主要存在两个问题。首先是经常观察到的拖车比拖拉机跑在里面的趋势，这种现象被广泛地称为“偏离轨道”。二是在控制意义上的倒车机动中，挂车的运动变得不稳定。针对这些问题，本文研究了利用液压缸控制挂车的悬吊位置，以减少或消除挂车的脱轨现象。首先，从几何关系出发，计算了消除偏迹所需的悬挂位置与机构中心的偏移量；结果表明，在几何约束所确定的牵引车转向角一定范围内，系统可以消除偏迹，但超过该范围后，系统就会出现偏迹，并随着牵引车转向角的增大而增加，当牵引车转向角超过该范围时，系统最终变得不可控。但是，该方法的减偏性能与以往研究中提出的车轮转向方法相当。然后构建了实验挂载位置控制器，并进行了验证实验。实验证实，在测试条件下，偏离小于5厘米。在此基础上，对挂车倒车控制理论进行了研究。在本研究中，我们将行进路径设计为在极坐标上用多项式函数表示的曲线。仿真研究表明，采用最优控制理论设计的局部线性化反馈控制器作为路径方程，可以实现拖车的准确、安全导航。

Objectives of this research are to realize easier driving and autonomous traveling in skill requested driving of trailers. There are two main problems in trailer driving. The first is the tendency observed frequently the trailer run inside than a tractor, this phenomenon is widely known as "off tracking". The second problem is the motion of trailer becomes unstable in backing up maneuver in the sense of control To solve these problems, in this study novel approach to reduce or eliminate the off tracking of trailer by controlling the hitching position of the trailer by using hydraulic cylinders. Firstly the required offset of hitching position from the center of the mechanism for elimination of off tracking has been calculated from the geometrical relations. As a result, the off tracking can be eliminated up to the certain steering angle of the tractor determined by geometrical constraints, but above the limit, off tracking appeared, and increased with steering angle of tractor, the finally the system became uncontrollable when the steering and of the tractor exceeded the limit. But, the off tracking reduction performance was found to be almost equal that of wheel steering method proposed in previous researches. Then the experimental hitching position controller was constructed, and verification experimental was conducted. It confirmed by the experiments that off tracking was lesser than 5cm in testing conditions. Following this research, control theory for backing up of trailer was investigated. In this study, we designed the traveling path as a curve expressed by the polynomial function on the polar coordinates. It has been verified by simulation studies involving simulated error that the trailer could be navigated accurately and safety when the path equation was used with locally linearized feedback controller designed by optimal control theory.