Research On The Control System Of The Hydro-mechanical Continuously Variable Transmission Of The Cotton Picker

The working conditions of the cotton picker are complex,and it needs to be engaged in various forms of operations such as picking,field walking,and road transportation.In order to adapt to the load and the speed of the cotton picker under various working forms,the cotton picker transmission usually needs to be set with more working gears,which leads to the complex structure of the transmission,inconvenient operation,and difficulty in ensuring economical efficiency.Hydro-mechanical Continuously Variable Transmission(HMCVT)is a new type of transmission device,which organically combines mechanical step transmission and hydraulic stepless transmission,so it has high transmission efficiency and strong resistance.The dynamic load impact capability can transmit large power and realize continuous stepless change of speed ratio,which is suitable for cotton pickers with complex working conditions.In order to improve the selfdesigned HMCVT,according to the basic requirements of the power transmission system of the cotton picker and the transmission characteristics of the cotton picker HMCVT,this thesis focuses on the HMCVT transmission control strategy of the cotton picker and the HMCVT control system of the cotton picker.The main research contents are as follows:(1)According to the HMCVT transmission scheme and transmission principle of the cotton picker,the transmission characteristics of the cotton picker HMCVT are studied,including the transmission ratio characteristics of the cotton picker HMCVT and the power split characteristics of the cotton picker HMCVT;The mathematical model of the main components of the HMCVT is established,including the mathematical model of the hydraulic speed control system and the mathematical model of the clutch;according to the HMCVT transmission scheme of the cotton picker,the HMCVT simulation model of the cotton picker is established in AMESim.(2)Aiming at the problems of poor output speed stability and difficult control of the hydraulic speed control system in the HMCVT of the cotton picker under the step input speed and external load disturbance,the neural network model-based reference adaptive control system,crowd search algorithm,PID Control technology and fuzzy theory of hydraulic speed control system output speed control strategy;in order to make cotton picker have better fuel economy,an economy-based engine-HMCVT speed ratio matching control strategy is proposed.The device is used to collect the engine accelerator pedal opening signal,and calculate the optimal economical speed of the engine under the engine accelerator pedal opening,and then send a control signal to the variable pump displacement ratio controller and the section change controller,to the cotton picker HMCVT The speed ratio is adjusted so that the engine speed is stabilized at the target economical speed under the action of the speed regulation characteristic.(3)Based on the STM32F407 single-chip microcomputer,the hardware design of the HMCVT control system of the cotton picking machine is completed,including the hardware composition and circuit design of the HMCVT control system of the cotton picking machine.The circuit includes the power supply circuit,reset circuit,clock circuit,JTAG interface circuit,RS-232 communication Circuit,analog signal acquisition circuit,switch signal acquisition circuit,electromagnetic directional valve drive circuit and electro-hydraulic proportional valve drive circuit;complete the software development of the HMCVT control system of the cotton picker,write the analog signal sampling program,switch signal acquisition Program,the main program of the cotton picker HMCVT control system,the cotton picker HMCVT segment switching program and the cotton picker HMCVT segment speed regulation program.(4)Select the power source,loading device,sensor,variable pump,quantitative motor,electromagnetic reversing valve,relief valve and clutch,etc.,and build a cotton picker HMCVT test bench;based on Lab VIEW and data acquisition card,complete the data Development of acquisition system;bench test of HMCVT control system of cotton picker.