以角速度为转向动作反馈的拖拉机自动导航控制系统

Navigation Control System for a Tractor which Used Angular Velocity as the Steering Feedback

针对传统农机导航控制系统中转向角度传感器安装麻烦、可靠性较低的缺点,采用角速度计作为拖拉机转向动作的反馈传感器,结合拖拉机加装的基于CAN总线结构的导航控制装置,设计了串级PID自动导航控制系统,内环PID控制器用于转向控制,外环PID控制器用于路径跟踪控制。由于角速度计噪声误差较大,为避免对角速度的积分运算引起误差持续累积增大,角速度计的测量数据仅直接用作内环PID控制器的反馈;外环PID控制器的控制量也设计为角速度值。因此,在以转向角为控制量的比例控制算法基础上,本文又推导、设计了以角速度为控制量的外环PID控制算法。路面实验结果表明,本文设计的以角速度为转向动作反馈的拖拉机自动导航控制系统,直线路径的稳态跟踪误差平均值约为4.1cm,误差绝对值最大为12.9cm,验证了角速度计在农机导航控制系统中应用的可行性及所提控制方法的正确性。

To counter the defects of complex installation and low reliability of steering angle sensor in the conventional ag -ricultural machine navigation control system , an angular velocity meter used as the Foton TA 800 tractor steering feedback sensor .Navigation control apparatus connected by CAN bus were mounted on the tractor , based on these apparatus , a cascade PID navigation control system was designed .The inner loop PID controller used for steering control , and the out-er loop PID controller used for path tracking control .Because of the comparatively large noise error of the angular velocity meter, integral operation would accumulate the error , to avoid integral operation , the angular velocity only used as the in-ner PID controller feedback .Correspondingly , angular velocity was chosen as the control variable of the outer PID control-ler.Accordingly,based on the proportional control algorithm which used steering angle as the control variable , an outer PID control algorithm which used steering angular velocity as the control variable was proposed .The experimental result indicates,the average tracking error of the straight line is 4.1cm,the maximum tracking error is 12.9cm.Therefore, it is feasible to employ the angular velocity meter as the steering feedback sensor in the agricultural machine navigation control system .