Hydraulic Four-wheel Steering Chassis Autopilot Key Technologies

Agricultural machinery automation and intelligence is the development direction of "precision agriculture".Agricultural tractor automatic driving technology can effectively reduce the workload of the driver, and effectively avoid the omission and overlap of the convergence line in the operation process, and greatly improve the working accuracy and working efficiency.Current automatic navigation technology has been more mature,but most of these systems are aimed at the agricultural machinery of two wheel drive.Four wheel drive four wheel steering chassis is less than two wheel drive two wheel steering chassis with strong steering, small turning radius, flexible operation, but the four wheel drive four wheel steering chassis automatic driving system is less studied.Therefore, this paper aims to of four wheel drive four wheel steering universal hydraulic chassis automatic driving technology research, design the automatic driving system of a kind of CAN bus communication of general hydraulic chassis, the hardware system is established, and the software program is compiled, and the overall performance test,which is meaningful to improve the automatic driving technology of agricultural chassis, and promote the development of "precision agriculture".The main research contents and conclusions were as follows:(1)The overall design of the system. According to the current research status and the demand of precision agriculture, the overall scheme of the universal hydraulic chassis automatic driving system based on CAN bus communication is established,and the chassis adopts four wheel drive four wheel steering system.(2)The design of a suitable model of agricultural machinery. According to the requirements of the automatic driving chassis, the design of a reasonable kinematic model, analysis of agricultural machinery in the movement process of the geometric model and the force model. The design of a reasonable navigation control algorithm,to provide the basis for the mathematical theory of agricultural.(3)Design control system.according to the navigation control algorithm, the design of a set of including driving state acquisition module, driving control module,vehicle computer and other navigation control system. Able to interpret the collectionof chassis movement information, and communication with the host computer. The driving controller selects DSP56F805, and designs its peripheral circuit. There are mainly, analog signal input and output interface circuit, CAN bus communication circuit, etc.. Car computer selection EPCS(4)Development of measurement and control program.Based on Ican protocol,written communication program and control program, achieves the chassis geographic location information and vehicle state parameters acquisition and processing and according to the navigation control algorithm, the output state control, chassis automatic driving software.(5) system performance test. Complete the hardware construction and software realization of the automatic driving system, according to the requirements of the chassis control, design the four wheel steering hydraulic chassis steering control test and path tracking test. Experiments show that the automatic driving system designed in this paper can realize the automatic control of the farm machinery chassis, and realize the automatic navigation.