Research On Automatic Navigation Control System Of Facilities Agricultural Vehicles

The application of the automatic navigation technology on Controlled Environmental Agriculture make the robot replaces farmers for monotonous field operation. Because of this technology, the accuracy, production efficiency and dependability about farming automation are improved effectively. Meanwhile the labor, labor intensity of drivers and the production cost are saved. The principle of automatic navigation control system of agricultural vehicle is using the sensors mounted on agricultural vehicle without farmers to get the external environment information. Then it control the agricultural vehicles to track the target path which was given automatically according to the navigation control strategy. The location method of ZigBee is selected, the location based on ZigBee and the method of navigation control are researched and experimented in this paper. The main contents of this paper are as follows:(1)The principle of measuring distance based on ZigBee and its errors are analyzed. A first-order filter is designed to filter RSSI signal and remove abnormal points. Path attenuation model of RSSI signal(mapping of RSSI and distance) is obtained by the experiment. Then Estimating distance dynamically by Kalman filter, and get the best estimates of distance.(2)The location based on measuring distance is analyzed. The location algorithm according to two base node is selected. The suitable calculation method of coordinate positioning and the layout program of base nodes in the Two-dimensional space are designed. Then posing the redundant positioning program, as well as the merge method of two groups of locations.(3)The steering control system is designed based on PID and calibrate the PID parameter by the bench. Then establish the path tracking controller based on fuzzy theory. The controller input variables are coordinate by locating and heading angle, the controller output variables are the correction of front wheel angle. And verify the feasibility of the algorithm through simulation analysis.(4) Finally, the software of path tracking control and monitoring is designed under the Visual Studio development environment. Then the navigation system is validated and the test data show that the navigation system has a high positioning accuracy and the steering system has a reliable tracking performance. The results prove the system can meet the requirements of agricultural vehicle path tracking control system.