| China is a large agricultural country and agriculture occupies an important position in the national economy of China.This topic takes the maize seed harvester as a carrier and addresses the problems of the traditional maize harvesting process,in which most of the driver’s energy is spent on operating the maize harvester to row harvesting,adjusting the height of the cutting platform and observing the harvesting situation.In order to reduce the labour intensity of the harvester operator and improve the automation level of the harvester,this thesis researches the key technology of automatic pair-row assisted harvesting of the harvester,which can realize automatic pair-row driving of the harvester in the maize field,adaptive adjustment of the height of the cutting platform and real-time monitoring of grain yield.The main work is as follows:(1)Aiming at the problems of complex modification,low control accuracy and high processing cost of the automatic steering system of the maize seed harvester,an automatic steering system based on the connection between the DC motor and the steering column is designed,mainly consisting of the automatic steering device controller,the automatic steering device actuating part and the original chassis steering mechanism of the maize seed harvester.For the safety of the system,the control strategy of switching the automatic steering mode to the manual takeover mode is designed.The control strategy for switching from automatic steering mode to manual takeover mode was designed for system safety,and the control threshold was determined.(2)An algorithm for crop row identification and navigation line extraction for maize maturity is proposed.A straight pass filter is used to filter the maize point cloud for ground and weeds as well as to extract the detection area,and a statistical filter is used to denoise and transform the point cloud coordinates.Then the least squares method is used to achieve crop row detection,and the boundary line between the area to be harvested and the harvested area is determined according to the crop row detection results,and finally the accuracy of the algorithm is verified with an average deviation angle of 0.85°.(3)The design of a maize grain harvester based cutter height adaptive system,mainly consisting of a cutter height measuring and profiling mechanism and a system controller.By installing a self-designed cutting platform height measuring mechanism on the side of the harvester,the height of the cutting platform from the ground during operation is measured in real time and fed back to the controller,which then controls the height of the cutting platform after receiving the feedback height information.(4)A real-time grain yield monitoring system is designed,the system mainly consists of a signal acquisition and processing module,a positioning module and a visualisation terminal,the acquisition frequency of the system is set to 1KHz and the response time consumed is 2ms,when the system is working,the signal acquisition and processing module detects the sensor signal duration of grain shading on the scraper of the grain lifter in real time,and uses the low-level signal based maize seeds constructed in this thesis to The lowlevel signal-based maize grain yield calculation model constructed in this thesis is used to complete the real-time yield measurement.The results show that the yield measurement error of the system is less than 5%.The field test was conducted on a Zoomlion 4YZL-5BZH combined maize seed harvester,and the average error of the yield measurement was 3.72%.The system can be used as a reference for precision farming and high yield management.(5)Based on what has been studied,the coordinated control between the systems has been designed.The communication protocol between the systems has been designed,the operation of the systems under three operating conditions has been formulated and the control software has been designed to achieve complete control of the harvester. |
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