Research On Electro-hydraulic Control Of Mountain Agricultural Machinery Drive Device Based On Hydrostatic Driv

The mountainous and hilly areas in China account for more than half of the land area,and the research on mountain agricultural machinery is crucial for promoting the rapid development of agriculture in China.Mountain agricultural machinery must have the characteristics of flexibility,miniaturization,strong climbing ability,high walking stability,and strong synchronous and cooperative ability of bilateral walking mechanisms.As the basic link of mountain agricultural machinery operation,it is of great significance to study the driving system suitable for our country’s mountain agricultural machinery operation environment.The hydrostatic drive has the characteristics of stepless speed regulation,flexible structural arrangement,and high specific power,which is more suitable for mountain agricultural machinery than other transmission methods.Therefore,this paper takes the tracked small mountain agricultural machinery driving device based on the hydrostatic drive as the research object and improves the dynamic response characteristics and antiinterference ability of its driving motor during driving through control algorithms to meet the driving requirements during operation.The thesis mainly completed the following research:(1)A hydraulic drive system with dual pumps and dual motors for mountain agricultural machinery based on the hydrostatic drive is designed.The drive form is to arrange the same closed pump control motor speed regulation circuit on both sides of the crawler chassis.The main hydraulic component parameters are calculated through the structural parameters and driving parameters of tracked vehicles.Taking the single side pump control motor speed regulating circuit as the object,the transfer function is derived,and the mathematical model and AMESim model of the pump control motor speed regulating circuit are established.After determining the parameters,the rationality of the designed hydraulic system is verified through comparative analysis of the simulation results under the condition of no control calculation using the two models.(2)The one-sided motor speed output exhibits shortcomings such as slow response and large overshoot when there is no control algorithm.To improve the dynamic response characteristics and anti-interference ability of the motor speed output of the pump control motor speed control circuit,and improve the driving performance of the vehicle,the principles of PID control,fuzzy control,BP neural network,and particle swarm optimization algorithm are analyzed,design four controllers and establish a joint simulation model based on the AMESim model of the pump control motor speed control circuit.On this basis,the response characteristics of four controllers for a single side loop under no-load conditions when tracking different expected signals are studied,and the anti-load interference ability when tracking expected signals under different load conditions is analyzed and compared through simulation results.The optimal control method for a single side loop is determined to be fuzzy PID control.(3)The vehicle driving demand is achieved by the coordination between the rotational speeds of both motors.Based on the satisfaction of the motor rotational speed output of a single side loop using fuzzy PID control,research on the rotational speed of both motors under straight and steering conditions is conducted.When the vehicle is traveling straight,by establishing a master-slave,parallel,and cross coupled synchronization controller,the synchronization control effect is analyzed by comparing the rotational speed output of the two side motors under three synchronization control methods.The simulation results show that the synchronization accuracy of the two side motors using cross coupled synchronization control is higher.When the vehicle turns in a differential steering mode,due to the different steering characteristics of tracked vehicles under different steering radii,when the steering radius is 0 ≤ R<B/2,the characteristic is that the speed direction of the outer track and the inner track is opposite;When the steering radius is R ≥ B/2,the speed direction of the outer track of the vehicle is the same as that of the inner track,but the size is different.Therefore,the simulation is conducted under two working conditions: the steering radius is 0 ≤ R<B/2 and R ≥ B/2.When the steering mode is determined,the steering control can be completed only by completing the adjustment and control of the rotation speeds of both motors.Therefore,the steering performance is determined by the control effect of the rotation speed of one side motor.Fuzzy PID control and BP neural network PID control with better control effect of one side loop are selected for simulation analysis of the steering conditions of both sides of the motor.The simulation results verify that the fuzzy PID control has better steering performance on both sides of the motor.