Design Of Control System For Self Propelled Round Bundle Straw Harvester

In order to improve the automation level of the self-propelled round bale straw harvester,it solves the problem that it is prone to blockage due to the excessive feeding amount during the operation.This paper uses the 9LRZ-5.2 self-propelled round bale straw harvester as the carrier.A set of straw harvester control system with controller as the core,machine-electricity-liquid phase combination,and man-machine interaction function is designed.The system adopts CAN bus communication,which can realize multi-terminal distributed control such as controller-display-engine ECU.It has the functions of working speed control,chemical spraying control,working load monitoring and automatic control of rope winding and unloading.The main research contents and conclusions are as follows:The overall scheme design of the control system of the self-propelled round bale straw harvester.By analyzing the working principle of the straw harvester,the cause of the blockage failure,the power transmission mode and the structural characteristics of the whole machine,a distributed control system scheme based on CAN bus communication was developed.Completed the scheme design of each sub-control system,hardware selection,electrical schematic drawing,and the construction and debugging of the entire control system.Mathematical model and simulation test of operating speed control system.By analyzing the working principle and working characteristics of each working part,the transfer function is calculated.Combining the characteristic parameters of each component,the mathematical model of the entire operating speed control system is finally established.Use the pid-tool in MATLAB to find a better combination of control parameters,and build a PID control system simulation model through Simulink to further verify the control effect of the PID parameters and provide a reference for the actual PID parameter tuning.Control process design and control program writing.With reference to the overall design principles of the control system software,the CAN bus application layer protocol was formulated.With the help of the Co De Sys2.3 software development platform,the programming and debugging of the controller and display application program are completed.The controller program adopts a structured programming method and is divided into two parts:the main program and the application subprogram.The main program includes CAN bus communication configuration,I/0 port configuration,and sensor data acquisition filtering.Application subprograms include speed control program,chemical spraying control program and rope-unloading control program.The display screen application program covers the design of the human-computer interaction interface and the writing of the underlying code.The human-computer interaction interface is composed of two parts:a monitoring interface and a parameter setting interface.Field test test and field load test.The field test tested the operating speed control system,the rope-unloading control system,the chemical spray system and the load monitoring system.The results show that all systems can work normally.The field load test verifies that when the work load is higher than the set load,the control system can control the work speed to stabilize the work load within the set range.For the control of the target speed in the field test,the adjustment time is less than 10s,the overshoot is less than 7%,and the steady-state error is less than 2%.Multiple tests and the transportability rope-unloading control system can be executed normally.The spraying test of the chemical liquid obtains the relationship between the PWM duty cycle and the spraying amount of the chemical liquid,which provides a control basis for the control of the chemical liquid spraying.The maximum torque of the working spindle measured in the no-load test is 86N·m,and the torque can reach 170N·m when the engine speeds up.Field experiments show that when the growth density of straw is 0.4～0.6kg/m~2,the operating speed is 7km/h,the maximum torque is530N·m,and the maximum load power is 91kw,the maximum allowable torque of the system is 583N·m and the maximum allowable load.It is 100kw,the operating speed adjustment time is less than 7s.In summary,the control system designed in this article can be realized by automatically adjusting the operating speed.The function of reducing the feeding amount to avoid clogging failure.In addition,it also has functions such as automatic rope unloading and spraying of chemical liquids,which enhance the automation capability of the straw harvester and provide a certain reference for the intelligent research of the straw harvester.