Research On Design And Control Method Of Hydraulic Driving System Of Crawler Tobacco Harvester

Due to the characteristics of fast response,high control accuracy and large output torque,hydraulic driving system has been widely used in agricultural crawler working vehicles in recent years.Agricultural crawler vehicles use hydraulic transmission schemes to replace some complex mechanical transmission intermediate devices,which can make the system structure more flexible,and the machine is lighter and lighter.At the same time,the hydraulic driving system also has high working efficiency and low failure rate.It is easy to maintain and operate.These features are undoubtedly a good choice for agricultural crawler vehicles.With the development of science and technology,hydraulic components will develop in the direction of miniaturization and close integration with microelectronic technology.Under the control of the micro processor,the control accuracy of hydraulic transmission technology will be further increased.According to the characteristics of tobacco harvester in hilly tobacco areas in Henan Province and the operating requirements of the crawler tobacco harvester,this paper designs the hydraulic driving system of the crawler tobacco harvester and the corresponding driving control method to realize the stable driving operation of the tobacco harvester in the hilly tobacco.In this paper,the driving system of the crawler tobacco harvester is made from six aspects: the design of the hydraulic driving system and the analysis of the hydraulic characteristics,the design of the software and hardware of the control part,the driving control method,the bench test,the modeling simulation,and the driving test of the harvesting vehicle.The research work is as follows:1.Starting from the car body characteristics of the crawler tobacco harvester and the operation mode of the hilly tobacco operation,a hydraulic driving scheme based on the form of dual pumps and dual motors is proposed,and according to the hydraulic system requirements of the crawler tobacco harvester power and two-speed driving,the power unit and hydraulic components in the driving drive system are calculated and selected to meet the functional requirements of the tobacco harvester during drivingand operation;from the variable plunger starting with the structural principle of the pump and the quantitative walking motor,the hydraulic characteristics of the driving hydraulic system are analyzed,and the driving system of the tobacco harvester is simulated and analyzed based on the AMESim software,and the hydraulic output characteristics of variable displacement pump and quantitative motor of the drive system are also analyzed when it is under three working conditions of slope full load starting,stopping and differential steering.2.In order to achieve the functional requirements of the driving system of the tobacco harvester,with modular design ideas,the software and hardware design of the driving control system of the tobacco harvester based on the EPEC3724 controller is completed,and a speed control handle is proposed for control execution The automatic throttle control scheme of the speed control handle has designed the corresponding rules of the position of the speed control handle and the driving state of the vehicle,and the control principle of the automatic accelerator control scheme of the speed control handle has been analyzed.3.Tobacco harvester control method of two driving system was studied in this paper.One is straight driving system and the other is steering driving system.The fuzzy PID control was used to control the output speed of the single-channel hydraulic motor.Aiming at the problem of double-motor synchronous speed output in straight-line driving,three common two-axis synchronous control methods were analyzed.Through the analysis of the three methods,the cross-coupled fuzzy PID synchronous control method was finally adopted;for the steering control problem,analyzed the three differential steering methods of the tracked vehicle during the steering process from the aspect of the vehicle movement,and comprehensively considered the four factors of the steering radius of the harvester,steering resistance,driving safety,and the matching method with the speed control handle,and finally adopted inboard decelerating differential steering method.4.In order to verify the control effect of the proposed single-channel fuzzy PID closed-loop control and cross-coupling double-closed-loop compound control,a simulation model and test bench for the dual-pump and dual-valve-controlled motor system were built.The test results show that in the step tracking test and the impact test,the fuzzy PID control is compared with the PID control,the system output speed steady-state error is less than 3r/min,the maximum speed difference under impact is less than 10r/min,and the stable adjustment time is 0.2s faster.It can be seen that thefuzzy PID control algorithm is superior to PID control in terms of stable motor speed output,anti-interference ability,and control response time;in the process of dual-axis synchronization test: Compared with the parallel PID synchronization speed control method,the double closed-loop fuzzy PID The output speed difference of the system under control has decreased by 55.6%,and the stable adjustment time has been shortened by 37.5% on average.5.A mathematical model of the hydraulic drive system and the vehicle steering dynamics of the tracked tobacco harvester were established.The two models were subject to simultaneity before simulated and analyzed in Matlab/Simulink software.The steering state of the harvesting vehicle was simulated under two steering modes of steering radius R ? B/2 and 0 ? R < B/2,then compared and analyzed the output effect of the PID control and fuzzy PID control on the single-channel pump-controlled motor system speed and the cross-coupling synchronization control under the dual-axis hydraulic motor speed.6.The basic driving test and field operation test of the crawler tobacco harvester were carried out.In the straight-line driving test,the control effects of single-channel PID control,single-channel fuzzy adaptive PID control,dual-channel cross-coupling PID compound control,and dual-channel cross-coupling are compared and analyzed from the two aspects of straight-line yaw rate and dual-channel motor speed output synchronization;in the steering driving test,the control effects of PID and fuzzy PID control algorithms are compared and analyzed from the stability of the output speed of the walking motor,the relative error of the steering radius of the harvester,and the slip and slip rate of the crawlers on both sides;in the field experiment,the driving performance of the harvester was comprehensively analyzed from power,steering,braking continuous driving and maneuverability performances.