关键词: 插秧机, 自动驾驶, 模型预测控制, MATLAB/Simulink, 路径跟踪

Abstract: Aiming at the phenomenon that the path tracking accuracy of the domestic automatic driving rice transplanter is not high, a path tracking method based on linear timevarying model predictive control is proposed. It is linearized and discretized the established nonlinear rice transplanter kinematics model, and performed model prediction path tracking control based on this model. It is established an objective function with the control increment as the state quantity. Considering the system control quantity and control increment constraint conditions, the objective function is converted into a constrained quadratic programming problem. The interior point method is used to solve the problem, the first element of the obtained control sequence is applied to the system, and the above process is repeated to achieve optimal control. In the MATLAB/Simulink environment, the model predictive control system simulation is built and compared with the Stanley control algorithm with a good path tracking effect. The results show that the predictive model controller is better than the Stanley control algorithm. Using a satellite signal receiver, electric steering wheel, and angle sensor to transform the Jingguan PZ60 rice transplanter, an unmanned test platform for the rice transplanter is built, and field tests are conducted. The test results show that the predictive controller based on the linear timevarying model can make the automatic driving rice transplanter carry out path tracking effectively when the speed is 1 m/s. The tracking error of the straight line segment is up to 202 cm, which meets the accuracy requirements of the automatic driving path tracking of the rice transplanter.

Key words: rice transplanter, automatic driving, model predictive control, MATLAB/Simulink, path tracking