基于干扰观测器的插秧机路径跟踪滑模控制

Sliding Mode Control for Path Tracking of Rice Transplanter Based on Disturbance Observer

针对插秧机作业时,因农田环境复杂及空间差异性,在未知外部干扰下车辆容易发生滑移,从而影响路径跟踪效果、跟踪收敛时间长等问题,提出了一种基于干扰观测器的插秧机路径跟踪滑模控制方法。首先,建立了包含滑移的扩展运动学模型,在此基础上引入横向和航向的复合干扰,设计非线性干扰观测器对干扰精准观测,降低滑模控制的抖振。为了避免奇异现象和提高收敛速度,提出采用快速非奇异终端滑模面和变指数幂次趋近律设计的控制器削弱干扰。在MatLab软件平台上建立了无干扰模型对比仿真,相比于快速幂次趋近律,选择的变指数幂次趋近律快速性更好,相比于快速终端滑模,设计的快速非奇异终端滑模动态性能更好。仿真结果表明:非线性干扰观测器能精确观测复合干扰;与无干扰观测器的滑模控制器相比,所设计的控制器能快速有效收敛、削弱干扰、降低抖振。在速度0.8 m/s的实际水田作业试验中,整体直线路径跟踪的横向平均绝对偏差为2.50 cm,均方根为2.90 cm,偏差总体数值较小,有效提高了控制系统稳定性和快速性,满足路径跟踪精度要求。

A sliding mode control method for rice transplanter path tracking based on interference observer is proposed to address the problems that the vehicle is prone to slip under unknown external disturbance during transplanter operation due to complex farmland environment and spatial variability,thus affecting the path tracking effect and long path tracking convergence time.Firstly,an extended kinematic model including slip is established,based on which the composite disturbances in lateral and heading directions are introduced,and a nonlinear disturbance observer is designed to accurately observe the disturbances and reduce the jitter of the sliding mode control.In order to avoid the singularity phenomenon and improve the convergence speed,a controller designed with fast non-singular terminal sliding mode surface and variable exponential power convergence law is proposed to weaken the disturbance.A comparative simulation of the interference-free model is established on the MATLAB software platform.Compared with the fast power convergence law,the variable exponential power convergence law selected in this paper is faster,and compared with the fast terminal sliding mode,the fast non-singular terminal sliding mode has better dynamic performance;the simulation results show that the nonlinear interference observer can accurately observe the composite interference;compared with the sliding mode controller without interference observer,this paper Compared with the sliding mode controller without interference observer,this paper can converge quickly and effectively,weaken the interference and reduce the jitter.In the actual paddy field operation test with the speed of 0.8 m/s,the average absolute deviation of the overall linear path tracking is 2.50 cm and the root mean square is 2.90 cm,and the overall deviation value is small,which can effectively improve the stability and speed of the control system and meet the path tracking accuracy.