Study On Load Control System Of Combined Harvester

Agriculture occupies an important position in China. The social told the grain production a higher request in the high harvest quality and efficiency. With the popularity of combine, the efficiency is improved and the grain loss is reduced. But in the process of trans-regional harvest, the combine's characteristics will change because of the different conditions. If operators can not timely adjust the combine's state, working efficiency will drop, failure rate will rise and the mechanical consumption will aggravate. In severe cases, the combine will be damaged. Combine is a complex system. Artificial control can't get a good control effect. Therefore, overall load control device must be designed to control the harvest speed automatically and keep the best state of combine.This research originates from the project in the National Science & Technology Pillar Program during the Eleventh Five-year Plan Period(2006BAD11A03). The final purpose of this paper is designing a combine load control system. For this reason, we extensive research the combine's characteristics, control algorithm, and the design of controller's software and hardware, etc. And we carried out a lot of test. Test shows that the control algorithm and the controller can adjust its control parameters according to conditions. The working efficiency is improved greatly based on the premise of keeping high working quality. Main contents focus in the work followed.1) In order to study the the combine's characteristics, inspect the control effect of algorithm, a computer simulation model of combines is designed. In the study, Bilang 4LZ2.0 combine, a crawler-type full-feeding transverse axial flow threshing cylinder harvester is choiced because of its representativeness. Each subsystem's working principle and characteristics are studied, such as the diesel engine, HST, transmission belt, header, crops conveyor, threshing cylinder, selected sieve, screw conveyor, etc. Their dynamical models and crop movement models are set up respectively. Furtherly, according to the combine's whole structure, all subsystem models are integrated judiciously, and the overall model of the combine is constituted. Based on this, a computer simulation model of combines is designed using Simulink. Kinds of steady characteristics and disturbance transient response of the combine are studied. Research shows that combined harvesters have serious nonlinear, and its model order is high, there are large inertia and pure delay links. Many parameters of the combine will change slowly. These parameters can't be identified accurately.2) In order to verify the effectiveness of the load control system, we have to carry out a lot of test under kinds of conditions. For the reason of speeding up the research progress and reducing the cost of research and development, a hardware-in-the-loop simulation model of combines is designed to simulate conditions in the test of load controller object. In the hardware-in-the-loop simulation, the emulation adapter receives control signals from the real controller. The mathematical model in the computer calculates the response of the combine. Then the emulation adapter outputs the response to the controller as feedback. A contrast test between the real combine and the hardware-in-the-loop simulation model is carryed out. A control signal is input to them. Test shows that the characteristics of the hardware-in-the-loop simulation model and the real combine are similar. The model can largely simulate the combine.3) To solve the problem of higher order, nonlinear, parameter drift, a load adaptive controller based on RBF neural network is designed. The characteristic parameters of combines are identified online by RBF network. An inverse model controller is constituted based on these parameters. The computer simulation test under different conditions showed that the controller can adapt to the parameter drift in a certain degree, and get a better control effect.4) In order to solve the large inertia, pure delay, and based on the research of external disturbances, a load-speed cascade controller is designed. A single neurons PID speed controller and a direct generalized predictive control load controller are designed to control the speed and the load respectively. The computer simulation test showed that the system frequency is improved by the speed controller. The controller can adapt the parameter drift and the disturbances, and get a very good control effect.5) An embedded combine load controller is designed based on the research above. The real-time simulation and field test on the 4LZ2.0 combine is carried out. The test showed that the controller can achieve the designed goals. It can control the overall load automatically, and achieve good working quality and working efficiency.