丘陵山地拖拉机车身调平双闭环模糊PID控制方法

Double Closed Loop Fuzzy PID Control Method of Tractor Body Leveling on Hilly and Mountainous Areas

为提高丘陵山地拖拉机自动调平控制系统性能,基于已开发的丘陵山地拖拉机姿态调整机构,提出了利用双闭环模糊PID算法调整车轮摆动角度的自动调平控制方法。首先,建立被控对象状态空间模型,并基于该模型设计了双闭环模糊PID控制算法。然后,对自动调平控制系统进行仿真分析,结果表明,在使用相同PID参数条件下,双闭环模糊PID控制比双闭环PID控制性能更优,可有效减少超调量和调平时间。最后,开展了静态和动态试验验证,结果表明,采用所提出的自动调平双闭环模糊PID控制方法,在15°坡地上调平时间为12.5 s,调平误差小于0.5°,且无超调现象,左右两后轮摆角绝对值差在±1°以内;同时,以1.98 km/h的速度行驶在高低起伏的恶劣工作环境下,车身倾斜角可控制在±3°范围内,左右摆动机构摆动角度绝对值差在±5°范围内,相比于双闭环PID控制效果更优。

In order to improve the performance of automatic leveling control system of tractors in hilly and mountainous areas, based on the developed attitude adjustment mechanism of hilly mountain tractors, an automatic leveling control method for adjusting the swing angle of wheels by double closed loop fuzzy PID algorithm was proposed. The state space model of the controlled object was established, and a double closed-loop fuzzy PID control algorithm was designed based on the model. The simulation analysis of the automatic leveling control system showed that the double closed loop fuzzy PID control had better performance than the double closed loop PID control, which can effectively reduce the overshoot and leveling time. A large number of dynamic and static tests were carried out. The results showed that the proposed automatic leveling double closed-loop fuzzy PID control method had a leveling time of 12.5 s on the slope of 15°, the maximum leveling error was less than 0.5°, and there was no overshoot phenomenon. The absolute value of the difference between the left and right rear wheel swing angles was within ±1°;at the same time, driving at a speed of 1.98 km/h in a harsh working environment with high and low undulations, the tilt angle of the body can be controlled within ±3°, and the absolute difference of the left and right wheel swing angles was within ±5°. Generally, the control method proposed had better control effect than double closed loop PID control.