Study On Path Tracking Control Technology Of Driverless Tracked Transport Vehicle

The field roads in hilly and mountainous orchards are tortuous and narrow,the labor intensity of agricultural transportation is high and the labor force is scarce,the efficiency of manual transportation is low,the mechanical transportation technology is backward and the transportation cost is high.Therefore,the automation of field transportation has become a key problem to be overcome,and solving this problem is of great significance to promote the modernization of agricultural production.In view of the requirements of improving the automation of field transportation operations,this paper focuses on the path tracking control technology of the transport vehicle based on the tracked transport vehicle platform,and studies the path planning and combined positioning technology before the tracking control to realize the automatic driving of the tracked transport vehicle.Finally,the navigation system platform is built and the field road test is carried out.The main research contents of this paper include:(1)According to the actual working environment of hilly orchard field,the sensor for environmental perception was selected to design and build the autonomous navigation system of transport vehicle.The positioning equipment based on the network differential global satellite positioning system(GNSS),the ZED binocular camera which can measure the depth information and the high precision inertial navigation sensor are selected.The positioning accuracy of GNSS equipment,the key parameters of binocular camera and the performance parameters of inertial sensor are determined by experiments.(2)Field aerial photography was collected for the orchard environment.According to the characteristics of aerial images,the image processing method of deep learning is selected to gradually create the characteristic map of orchard environment,which lays the foundation for the next path planning.(3)Through the significant semistructured characteristics of the orchard,the driving mode of the transporter in the orchard was determined,and the full coverage driving and the optimal path driving from the starting point to the end were completed.The global path planning of the transporter was completed,and the simulation experiment was carried out on the software platform.(4)The fuzzy PID control of transit vehicle path tracking.The fuzzy PID controller based on preview is used to adjust the PID parameters in real time by analyzing the motion of tracked vehicle,and the steering control method of tracked vehicle is designed.The deviation information of the current positioning and preview position is selected as the input of the tracking controller,and the speed of the two-way motor is used as the output of the controller.The fuzzy PID controller and the steering tracking model of the transporter are built on the MATLAB / Simulink software platform,and the path tracking simulation of the system is carried out.The simulation results show that the fuzzy PID control effect is better than the classical PID control,which can improve the stability of the automatic driving of the transporter in the orchard field road.(5)Field road driving test.In order to verify the effectiveness and feasibility of the path tracking control strategy,based on the orchard field road transport vehicle platform,the hardware system of the vehicle multi-sensor and vehicle control is built.The field experiment of the vehicle is carried out on the typical hilly mountain orchard field road.The effectiveness of the fuzzy PID control algorithm is verified,and the actual effect of the path tracking control through the fuzzy PID method is verified.According to the field road driving test results of the transporter in an orchard base in Chongqing,the fuzzy PID method adopted can realize the path tracking control of the transporter.The driving test results show that the lateral deviation of the track of the transporter in the field cement road is 6 cm,and the lateral deviation of the track in the field soil road is 13.6 cm,indicating that the accuracy of the path tracking control method is high,which can meet the requirements of the automatic driving of the transporter in the and mountainous orchards.