Design And Development Of Spray Pressure Controller For Agricultural Spray Machinery

In the process of modern agricultural development,the intelligent development of agricultural spray machinery has become the key factor of modern agricultural progress.The traditional agricultural spray machinery have the disadvantages of not to standard of operating parameters,low efficiency,and imperfect control system structure of spray system,due to the issues of its complex working road conditions,terrible working environments,longer working hours,operating conditions of engine,driving state of machine and weather conditions.It has impacted on the design of the spraying control system in agricultural spray machinery.It leads to the waste of pesticides and the destruction of the ecological environment.Therefore,it is urgent to solve the issue of intelligent control of the spraying control system in agricultural spray machinery.Based on the structure and operating mechanism of the agricultural spray machinery system,the thesis establishes the mathematical model agricultural spray machinery spraying system.In order to ensure that the operating parameters of the agricultural spray machinery system can be adjusted with high accuracy and the control system have a complete control strategy,and then the use and efficiency of the agricultural spray machinery can be improved.Designing the spraying pressure controller based on the steady-state feed-forward and combination of state feedback and PID control for the agricultural spray machinery which makes the spray pressure tracking the set pressure quickly and stably.Simulink software is used to simulate the spraying system of agricultural spray machinery in a variety of complex conditions,compared with the effect of the traditional PID controller to verify the control effect of the controller based on the steady-state feed-forward and combination of state feedback and PID.In order to meet the requirements of engineering implementation,combining embedded technology and CAN bus technology to design the spray pressure controller of agricultural spray machinery and develop a CAN bus communication protocol for agricultural machines meeting the spraying system of agricultural spray machinery,based on the valid verification of the spraying system of agricultural spray machinery in Simulink.STM32F103RBT6 is selected as the embedded core controller in hardware,and the peripheral expansion circuit,CAN bus communication circuit and display circuit are designed.The software has completed the embedded program of control strategy,communication protocol program for spray control system based on CAN and LCD display program.The controller performance verification adopts the hardware-in-the-loop approach,using the CAN bus module to achieve communication between the host computer and the embedded controller.The host computer simulates the spraying system of agricultural spray machinery,and the lower computer is the embedded controller.The experiment results show that the designed controller based on steady-state feed-forward and combination of state feedback and PID for agricultural spray machinery can achieve control effective and meet the engineering requirements so that the spray pressure can track the set pressure quickly and stably,achieving the purpose of control.It also realizes the data transmission between the designed controller and the spraying system of agricultural spray machinery and displays the operating status of the spraying system of agricultural spray machinery accurately.