Design And Research Of Variable Control System For Unmanned Aerial Vehicle

At present,the regular pesticide spraying operations are only carried out at constant rate of flow and can't achieve uniform spray for the whole farmland as the spraying system moves at variable speed,which may cause great waste of pesticides,pesticide residues and pollution to the eco-environment,consequently harming people's health.The reduction of pesticide is significantly important for the sustainable development of eco-environment.Therefore,a variable-rate spray system,based on unmanned aerial vehicle(UAV),was designed and the performance of the spraying control algorithms were analyzed.The spray control system performance was evaluated by comparing the simulated and actual results of variable-rate spray with different controlling methods.The main creative results were achieved as follows:(1)An embedded flow-rate control system based on fuzz control algorithm was designed in accordance with the flight speed of UAV.STM32 processor processed the real-time data sent from GPS speed sensor and Hall-flow sensor to achieve the final goal that the flow-rate varied with the change of the speed of UAV.(2)A flow-rate control system based on fuzzy control algorithm was designed and the actual flow-rate,target flow-rate deviation and the change rate of the deviation were taken as input while the duty cycle on the control panel as output.The actual output flow was corrected real-timely.Comparing the simulations of fuzzy control algorithm,PID control algorithm and one excluded from control algorithm,respectively.The results showed that the settling time and the overshoot of the system was 4.5s and 38% without control algorithm,2.5s and 7% within PID control algorithm and 1.5s and 3% within fuzzy control algorithm,respectively.The performance of the flow-rate control system was improved greatly since fuzzy control algorithm was applied.(3)Experimenting on the variable-rate spray system based on UAV,the results showed that the flow varied with the change of the speed of the UAV.The response lag was as long as 2.5s when control algorithm was not applied and 1.5s when PID control method was applied.However,the response lag was 1s when fuzzy control was applied.Fuzzy control had obvious advantages over the other two control methods.