Research On The Height Adjustment System Of Combine Header

At present,the automation degree of combine harvesters' header is relatively low in China,and there is relatively little research on the automatic adjustment of the height of the header of combine harvesters.The change of the height of the combine harvesters' header depends on the driver's manual adjustment based on their experience.In the process of manual adjustment,the main problems exist in the manual adjustment process are inaccurate adjustment,low efficiency and driver workload's increasing.In view of this situation,this paper studies a kind of automatic adjusting system for the height of header of combine harvester.It mainly carried out the following aspects of work:The corps' height detection device based on Infrared unilateral reflection has been put forward,and the stability of the device in the working process and the maximum measurement range under different light conditions have been tested.On the basis of the existed hydraulic system of the combine harvester,the manual commutation valve controlling the movement of the header is replaced with three four-way electromagnetic reversing valve,and a method of realizing the lifting platform by changing the closing time and direction of the electromagnetic reversing valve is proposed.At the same time,in the process of realizing the automatic adjustment of the height of the combine harvesters' header,a control strategy which uses the fuzzy PID control algorithm to convert the adjustment of the height of the header of combine harvesters into the closing time of the electromagnetic reversing valve has been studied.The control method of the system control unit and communication process are being studied,and all the procedures needed to realize the control function of the control unit are being designed.On the basis of the completion of the control unit,the test platform is being built and the test scheme is being designed.The adjustment precision of the system and the response time of the system in the working process are tested and analyzed,and the control scheme of the system is being optimized and improved.The system overall simulation test of rice was carried out to verify whether the system has a good stability in the working process,and whether the the header of combine harvesters was running smoothly and the adjustment is accurate when it automaticallyadjusts the height.The system response time test results show that during the working process of the header of the combine harvester automatic adjustment system,the response speed of the header's rise and fall are 0.24m/s and 0.17m/s,which satisfies the standard of the header's rising speed not less than 0.2m/s and the falling speed not less than 0.15m/s.The accuracy of header of the combine harvester height adjustment test shows that when the system is working,the adjustment error range is 0-3cm.At the same time,the detection error range of crop height detection device is 0-2cm after testing.