| The development of electronictechnique, computer technique, artificial intelligence technology and other technology promote electromechanical integration technology application to tractors. Using the technology of electro-mechanical and hydraulic technology is the best project for raising technical level, increasing the intelligent degree and solving numerous facing technical difficulties. Tractors’development direction is intelligentialize. Hitch control system on traditional tractor is being replaced by electro-hydraulic hitch control system.Design of tractor electro-hydraulic hitch system is introduced based on the analysis of traditional hydraulic hitch system. Electro-hydraulic hitch system use electrical control proportional valve to replace the traditional splitter, use control panel to replace the traditional hand level, and the control core is a SCM. This paper analyzed the power losing on traditional hydraulic system, designed hydraulic hitch system oil circuit, A mathematical model of valve control cylinder is established. The oil circuit makes the tractor more energy efficient than traditional tractor.This paper analyzed merits and demerits of force control and position control for tractor electro-hydraulic hitch system, introduced force-position switching control method, analyzed its merits and demerits. Put the comprehensive coefficient forward, comprehensive coefficient participates the process of force-position combined control, and introduced the concrete method. The comprehensive coefficient transforms the combined control into fuzzy control of cylinder displacement. This paper designed fuzzy controller.In order to verify the feasibility of this system, this paper use KAT1404Model, simulated the hydraulic system and control system by AMESim and MATLAB/Simulink software. Build the simulation model of hydraulic system and control system, and analyzed the results of response on different comprehensive coefficient, verified the feasibility of force-position combined control and fuzzy controller, meanwhile proved the feature of energy-efficiency on hydraulic system.The force-position combined control of tractor electro-hydraulic hitch system needs controller and program. The controller is based on SCM. This paper designed sensor signal acquisition circuit, power circuit, control panel circuit and signal output circuit. Software parts, use C language program the whole system, includes main program, AD conversion program, raise and drop program, PWM output program, fuzzy control program. In the program, module is designed to improve system security and reliability.This paper build test bench on CAT, did experiment on the bench, got displacement curves of electro-hydraulic hitch system under different comprehensive coefficient, compared these curves with the simulation curves. The experiment results show that the system can implement closed loop control, and force-position control method and fuzzy controller apply to tractor hydraulic hitch system. |
PDF Full Text Request