Research On Track Vehicle Path Tracking Algorithms

Currently,all aspects of agricultural production in China are developing towards precision agriculture and intelligent agriculture,and various agricultural machinery and equipment are gradually realizing automatic navigation operations.Crawler chassis is a common form of chassis in agricultural machinery and equipment.Studying track chassis path tracking algorithms is of great significance for improving the operational accuracy of tracked vehicles.Based on RTK(Real-Time Kinematic)technology,this paper designs a track tracking system for tracked vehicles,laying the foundation for the subsequent development of the Panax notoginseng combine harvester.The main research contents are as follows:(1)According to the working characteristics of tracked vehicles,the corresponding electric control modification scheme is designed,and the hardware equipment and circuit structure used are introduced in detail.The corresponding sensors are installed at the engine and driving wheel of the tracked vehicle,and the corresponding actuating elements are installed at the turning,clutch,throttle,and other control structures.The lower computer is responsible for collecting sensor signals and sending control commands to realize the monitoring and control of the running status of the tracked vehicle.(2)The lower computer integrates the Free RTOS real-time operating system and light weight IP protocol,ensuring the stable operation of various functions of the lower computer and improving the reliability of communication with the upper computer.The upper computer uses C# language to design the control interface,which can display the relative position relationship between the current position and the planned path in real time and realize the path planning function.(3)In order to give full play to the advantage of small turning radius of tracked vehicles with unilateral braking and reduce the error area in the process of large angle turning,this study proposes two control strategies for small angle and large angle paths.In the face of small angle turning path,this study designs a fuzzy controller based on the preview tracking model and optimizes the selection of target points to reduce the error area of turning path.The large angle turning strategy plans the optimal turning target point according to the turning instantaneous center of the tracked vehicle when facing the large angle path,so that the tracked vehicle can turn to the target heading at one time.The simulation results show that the average error area is reduced by 73.5%and the number of turns in the whole path is reduced by 71.1% by adding a large angle turn control strategy based on the fuzzy controller,which improves the control efficiency and reduces the path tracking error.(4)In order to further verify the effectiveness of the large angle turning strategy,this study build an automatic navigation experimental platform on a tracked transport vehicle,design an experimental path containing multiple large angle turns,and carry out multiple groups of real vehicle experiments on the open field.The experimental results show that at a driving speed of 0.2m/s,the error area of using the large angle turning strategy is reduced by 35.7% compare with not using it,and the number of turning control in the turning area is reduced by 33.0%,and the experimental results of using the large angle turning times are less affected by different load conditions and forward looking distance,which fully reflects that the system has good antiinterference ability and meets the requirements of automatic navigation of tracked vehicles.