Research On Plowing Depth Automatic Control For High-Power Tractor Electro-Hydraulic Hitch System

With the maturing of agricultural economy and the development of modern information technology, our country is now in a transitional time in which traditional agriculture is turning into modern agriculture. The study of tractor hydraulic hitch is related to the successful transformation of agricultural modernization, because tractor is an essential agricultural engineering equipment. Based on current research status at home and abroad, the key question to realize tractor electro-hydraulic hitch technology was introduced in this paper.The tractor electro-hydraulic hitch was upgraded on the basis of the tractor prototype of ‘Huanhai-Jinma’-1204. The traditional hydraulic distributor was replaced by electro-hydraulic proportional direction-changeover valve, control panel was applied instead of manipulation mechanism, the status parameters of tractor were collected by sensors, and the control information based on collected data was sent by controller. Eventually, the function of force control, position control and force-position combined control were realized in the upgraded tractor. The level of farming automation had been raised, meanwhile the quality and efficiency had also been significantly improved.The resistance coefficient was introduced in the relationship of deep tillage and traction to reduce the deviation between set tillage depth and actual tillage depth. And the dual-mode control strategy, that the fuzzy control is adopted after proportional control, was proposed to improve the response speed and accuracy of the system.The designed controller was based on Freescale MC9S12XS128. The hardware circuit mainly includes a minimal system, signal acquisition circuit, CAN communication circuit, serial communication circuit, liquid crystal display circuit, etc. And the program of the system controller was developed by C language, mainly including the main program, A/D acquisition subroutine, CAN sending subroutine, serial port sending subroutine, LCD subroutine, automatic control subroutine, etc.For monitoring the status information of tractor and recording the test data when plowing, the multichannel data acquisition program of tractor electro-hydraulic hitch software was designed based on LabVIEW. Finally, the field experiment was taken to verify the feasibility of the designed system. Through the analysis of experimental data, the tractor electro-hydraulic hitch system realized the adjustment of the tillage depth and force parameter and also achieved satisfying experimental results.