论文部分内容阅读
以东方红X-804拖拉机为平台,开发了一种基于RTK-DGPS定位和双闭环转向控制相组合的农业自动导航系统。系统主要包括RTK-DGPS接收机、姿态航向参考系统(AHRS)、转向控制器、电控液压转向装置和转向角检测传感器。设计了Kalman滤波器对定位数据进行平滑处理,同时实现航向角的校正。为实现自动转向,在拖拉机原有手动控制系统基础上加上电控比例液压阀,并设计电控单元。然后,推导了转向系统的数学模型,通过Matlab仿真工具箱得到传递函数的参数,设计了双闭环转向控制算法。最后,进行了算法验证试验和田间试验,结果表明,双闭环控制方法较好抑制了稳态时的震荡现象,方波信号的角度跟踪稳态时最大误差0.60°,平均误差0.40°,平均延时为0.20 s;设计的Kalman滤波器有助于提高定位系统的精度,横向跟踪误差不超过0.09 m,转向角度平均跟踪误差为0.43°,延时0.25 s。
Based on the Dongfanghong X-804 tractor, an agricultural automatic navigation system based on the combination of RTK-DGPS positioning and double-loop steering control was developed. The system mainly includes RTK-DGPS receiver, attitude and heading reference system (AHRS), steering controller, electronically controlled hydraulic steering and steering angle detection sensor. The Kalman filter is designed to smooth the positioning data and to correct the heading angle. In order to achieve automatic steering, electric proportional hydraulic valve is added to the original manual control system of the tractor, and the electronic control unit is designed. Then, the mathematical model of the steering system is deduced. The parameters of the transfer function are obtained through Matlab simulation toolbox, and the double closed-loop steering control algorithm is designed. Finally, the algorithm verification test and the field experiment are carried out. The results show that the double closed-loop control method can restrain the oscillation phenomenon at steady state, and the maximum error of the square-wave signal tracking steady state is 0.60 ° with the average error of 0.40 °. The average delay 0.20 s. The designed Kalman filter can improve the precision of the positioning system. The horizontal tracking error is less than 0.09 m, the average tracking error of the steering angle is 0.43 °, and the delay time is 0.25 s.