| As an important part of combine harvester,the working performance of header has a direct impact on the stability of feeding quantity as well as the operation efficiency and quality of the machine.The field experiment showed that the height of header too low would make stubble remain too short and increase the feeding amount of header,which was easy to cause problems such as soil blockage of cutter,blockage of header feeding auger,excessive load of threshing drum and so on.On the contrary,if the stubble was too high,it would also affect the planting of next season crops and straw recovery.In addition,the matching relationship between reel speed and operation speed would also directly affect the working performance of the header.When the reel speed was too fast,it would increase the impact on the grain.When the reel speed was too slow,the straw would be pushed down by the header cutter,increasing the grain loss of the header.Therefore,according to the field operation environment,real-time adjustment of header working parameters and matching with the operation speed was an effective way to ensure the operation performance of combine harvester.Aiming at the problem that domestic combine harvesters can only harvest one or two crops at the present stage,it is difficult to harvest multiple crops with one machine,because the header will suffer large amount of grain loss when harvesting different crops.This paper designed a set of intelligent regulation system for the adjustment of operation parameters of multi crop harvesting header,so as to realize an optimal match among the height of header,the reel speed and the forward speed of the machine.in order to enhance the intelligent level of the machine,reducing the fluctuation of feeding amount and significantly reduce the grain loss of header.The main research contents are as follows:(1)The mechanical contact ultrasonic combined header profiling system was developed to ensure the stability of stubble height.Aiming at the problem of inaccurate measurement results caused by various factors such as environment and terrain when measuring the height of header with a single sensor in combine harvester,a profiling device composed of two mechanical contact profiling plates and two non-contact ultrasonic sensors was designed.Based on the multi-sensor data fusion processing technology under BP neural network,the header height measurement system was developed.The system can filter and optimize the signals collected by two ultrasonic sensors and two angle sensors according to different weights and fusion targets.The test results showed that the measurement error of header height is≤ 15 mm after the application of the system.On this basis,the header height control system is developed based on the hydraulic proportional solenoid valve.The header height hydraulic adjustment system was simulated and analyzed by AMESim software,and the fuzzy PID control algorithm was used to realize the header height adjustment.The test results of harvesting rape,millet and rice showed that under the header height automatic control system,the harvest effect was better,the crop stubble height was relatively flat,which could meet the requirements of automatic regulation of header height of multi-crop combine harvester.(2)According to the movement track of the reel when harvesting crops,the optimal range of reel speed ratio suitable for harvesting different crops(rape,millet and rice)was studied.In order to reduce the grain loss of the header caused by too fast or too slow rotating speed of the reel when harvesting crops,according to the motion track of the reel when harvesting crops,the best harvesting speed ratio suitable for rape,millet and rice was found in range of λ,so that it could not only meet the matching of reel speed and forward speed when harvesting different crops,but also made the ratio of reel speed in the appropriate range suitable for harvesting the crop,so as to further reduce the grain loss of header.According to the field experiment and experience,it could be obtained that the speed ratio λ suitable for rape harvest is 1.2 ～ 1.6.The range 1.2 ～ 1.7 was suitable for millet harvesting and the range 1.4 ～ 1.8 was suitable for rice harvesting.The research results can lay a foundation for the development of the matching control system of header height,reel speed and the operating speed of the machine.(3)The reel speed ratio λ was established and the mathematical model of operation speed matching adjustment,the matching control algorithm between reel speed and operation speed was developed based on Fuzzy PID technology.The hydraulic motor with appropriate speed range was optimized,the hydraulic flow of the hydraulic motor was controlled by adjusting the opening of the proportional solenoid valve,and the hydraulic system of reel speed adjustment was simulated and analyzed by AMESim software to verify the feasibility of the system and realize the stepless adjustment of reel speed.Based on STM32 microcontroller and fuzzy PID control algorithm,the software and hardware system of header parameter regulation of multi crop combine harvester was developed,and the field experiment was carried out.The field test results showed that the header loss rate of rape,millet and rice was only 1.19%,0.41% and 0.35% after using the matching algorithm of reel speed and operation speed in the range of the best reel speed ratio,which proved the effectiveness of the developed system. |
PDF Full Text Request