东方红拖拉机自动转向控制器设计及试验

以东方红-X804拖拉机为试验平台,设计了基于双闭环控制方法的转向控制器,以提高农业机械导航的精度。首先阐述了系统整体结构及工作原理,使用角度传感器KMA199和角速率传感器ADIS16300分别测量转向角度、转向角速率,电控液压阀、换挡电磁阀和溢流阀作为执行单元实现自动转向。建立了数学模型,介绍了转向控制器的硬件电路实现,设计了CAN总线网络功能节点。结合拖拉机田间作业过程中系统非线性特性,提出了以角速度控制为内环、转向角度控制为外环的双闭环控制方法,给出了控制算法的推导过程,并使用Matlab工具箱进行系统辨识得到传递函数的参数。试验结果表明:ADIS16300角速度积分的角度值有较高准确度,平均误差为0.53°。方波信号的角度跟踪稳态时平均误差为0.40°,平均跟踪时间为1.3 s,角速率跟踪稳态时平均误差为1.25(°)/s,延时时间平均值为0.2 s;双闭环控制方法较好抑制了稳态时的震荡现象。

Design and experiment of automatic steering control system based on Dongfanghong tractor

A Dongfanghong-X804 tractor was used as a platform and an automatic steering controller based on double closed-loop control was developed to realize autonomous navigation of agricultural machinery.The make-up of the whole steering system and the working principle are presented: using an angle sensor KMA199 to measure steering angle and a gyroscope integrated in ADIS16300 to measure angular rate.In order to realize servo control of steering system, electro-hydraulic valves, shift solenoid valve and relief valve were used as actuators for automatic steering.Then the mathematical model of steering system was derived and the hardware circuit realization was described with CAN network design.According to characteristic of the system nonlinear, the transfer function between the proportional valve input current and steering angular can be seen as a second-order inertial part and a latency part, and a double closed-loop control algorithm for steering system was designed, using Matlab System Identification Toolbox to estimate transfer function parameters.Finally, tests were conducted to examine the steering system, including a calibration test for ADIS16300, which indicated the high accuracy of ADIS16300 angular velocity integral values, with the average error of 0.53°; and a test of the steering control system was carried out to verify the performance of double closed-loop control algorithm, which showed that the steering control system solved the control overshoot well and the average error is 0.4°, with 1.3 s tracking time; the average angular rate tracking error is 1.25 °/s, with 0.2 s tracking time.