Development Of Load Feedback Equipment Of Combine Harvester Based On Gray Predictive Fuzzy Control

Combine Harvester is important agricultural equipment widely used in agriculture production. Its widespread use enormously reduces the farmers' labor intensity and enhances the work efficiency. With the rapid development of microelectronics and computer technology, the automation level of combine harvester is increasingly improved. But compared to foreign countries, our combine harvester is usually manual operated by tractor driver and the automation level is low. Usually, the improper operation of driver will lead to overloading and then cause stoppage and other breakdowns. Thus the work quality is affected. A stable load is the premise that combine harvester would acquire the best threshing performance and high work efficiency.While the load of combine harvester is related to crop density and humidity, the soil conditions in the field, cutting width and forward speed etc. Compared to other influencing factors, to stabilize load by controlling forward speed is more convenient and feasible. Therefore it means a lot to study load feedback control equipment for realizing automatic control of combine harvester's forward speed. Thus, it is very important to design a control system, which can adjust the speed according to the load. According to the structural characteristic of the whole-feed combine harvester model 4LZ-2.0, this paper mainly introduced the design of load feedback control equipment of combine harvester based on grey prediction fuzzy control. This equipment controls the speed of combine harvester to keep the load stable. Specific contents include the following aspects:1 Analyzing the working process of combine harvester, aiming at the properties of nonlinear, time varying and delay, this paper used fuzzy control with grey prediction algorithm to control the speed of combine harvester and keep the load stable. A two-dimensional predictive fuzzy controller was built, whose input signals were deviation and its change rate of the rotational speeds of cylinder and screw conveyor and output signal was the controlling plus of servo stepping-motor.2 Based on the hydraulic continuously variable transmission on the testing combine harvester, the load feedback speed control equipment with manual/automatic integration function was designed. In the control system, the controller is C8051F020 MCU which is enhanced 51 series MCU. The three speed signals of cylinder, screw conveyor and forward speed are measured by hall rotate speed sensors. The equipment controls the step motor which controls the forward speed by push rod of hydraulic CVT to keep the load of combine harvester stable.3 The fuzzy control with grey prediction algorithm was realized in MCU and the source program was compiled by the C language. The dynamic model of the combine harvester and a partial simulation model of control system were established with Simulink software. The results of simulation and field experiments proved that this controlling algorithm was practicable and the equipment could keep the combine harvester stable load and high work efficiency.