Path Tracking Study Based On Agricultural Tractor

Tractor autonomous navigation system not only improves agricultural productivity and relieve fatigue, but also collects different kinds of information and reduces pollution. This paper study on path tracing in tractor autonomous navigation system combined with the environment of actual farmland based on TN654. Then a solution about path tracing was proposed and position and orientation about tractor were studied on。Then a new solution combined fuzzy control with pure tracing method was presented and path tracking experiments were to test the idea that look-ahead distance can realize self-adjusting to improve robustness and adaptability. The main research contents are as follows:(1) This part aims to design a path tracing solution based on practical demands containing integr ity and feasibility, which includes: path design、tracing design、realizing functions、monitor terminal and operative part.(2) This chapter study on position and front wheel angle about tractor,longitude、lat itude and speed of east、north and up are processed by Kalman filter. In addition,combing angular displacement sensor with Kalman prediction model was used to estimate front-wheel steering angle in condition of static and dynamic state respectively. Results show standard deviation no more than 2 degree in static and average error at 2 degree in dynamic.(3) This section focus on path tracing method, contrasting fuzzy control with pure tracing method, a method was presented combined fuzzy control with pure tracing method while lateral error、heading error and look-ahead distance using fuzzy control. In order to achieve path tracing, using fuzzy control to realize look-ahead distance adaptively while different lateral error and heading error. It simulates the response curves of the same lateral error with different heading errors and the same heading error with different lateral errors respectively,which used Matlab / Simulink. Results of simulation indicate that the look-ahead distance is self-adjusting..(4) Path tracking experiment. This experiment contain laboratory experiment, bench test and path tracking experiment. laboratory experiment simulate the real move of front wheel and to test the solution about path tracing is right or not. Then the bench test concludes that τ getting 0.32 can describe the execute part taking considering hydraulic drive. Finally, the path tracking experiment concludes that the solution is useful,average error is 4.75 cm in the case of the speed of 1m/s and cement road.