| With the development of agricultural technology,large-scale plant protection machine has become an essential agricultural machinery in modern agriculture.The spraying system of plant protection machine is composed of diaphragm pump,regulating valve,nozzle and so on.The system has the characteristics of uncertainty,variability by time and nonlinear.How to achieve the optimal spraying quantity under different travelling speeds of plant protection machine is of great significance to improve efficiency,ensure the uniformity of spraying,reduce cost and reduce pollution.Therefore,the main research work of this thesis is as follows:Firstly,this thesis analyzes the principles and control characteristics of the current mainstream large-scale plant protection machine and spraying system at home and abroad,and then establishes a mathematical model for the spraying system composed of diaphragm pump and electric valve in common use.The accuracy of the model at different operating points is verified by laboratory simulation.Secondly,in view of the time-varying and non-changing characteristics of the system,the self-adaptive control strategy of single neuron PID is adopted to solve the spray flow control problem.The simulation results show that the control method of single neuron PID has better control effect than the conventional PID control.Thirdly,based on STM32F407ZGT6 chip as the core processor,the hardware circuit of the system is designed,and the design of digital,analog,drive amplifier and display circuit is completed.Based on C language,the corresponding software system is developed,and the design of main program and control strategy module,communication module and other related functional modules is completed.Finally,in order to verify the control algorithm,control effect and software function,it’s verified on the variable flow platform of plant protection machine in the laboratory,and the comparison experiment between single neuron PID control and incremental PID control is carried out.The result of the experimental shows that the controller can stably control the output spray amount consistent with the set spray amount.Compared with the incremental PID control,the single-neuron PID control has the advantages of small overshoot,high stability and fast response,and the error can meet the engineering requirements. |
