Design And Research On Variable-Rate Spraying Control System For Helicopters

The annual economic losses caused by pests and diseases of crop and forest vegetation in China are great.The traditional plant protection operation methods are slow and ineffective.The problem of pest control in agriculture and forestry is becoming increasingly prominent.Pesticides play a vital role in the pest control process,but excessive use of pesticides brings many problems,such as low pesticide utilization rate,excessive pesticide residue of agricultural products,and environmental pollution.The agricultural aviation variable-rate spraying technology can effectively solve the above problems.Its outstanding advantages are mainly in the speed,high efficiency,good quality,low cost.It can effectively treat sudden pests and diseases,and can effectively improve the utilization rate of pesticides,reduce pesticide waste and reduce pesticide residues.This paper mainly designs and develops the helicopter airborne variable-rate spraying control system,using PID control algorithms and electric ball valve switch as variable regulating actuator.The main contents are summarized as follows:(1)Aiming at the development status and demand of variable-rate spraying technology in precision agriculture in China,the overall scheme design of manned helicopter airborne variable-rate spraying control system was carried out,and the design goal and system composition of variable-rate spraying control system were determined.The working principle of the system,the variable-rate spraying control algorithm,the GNSS data acquisition and analysis,and the communication protocol between the controller and the navigation terminal are deeply studied.(2)The design and construction of the hardware part of the manned helicopter airborne variable-rate spraying control system was completed,including the variable-rate spraying control system liquid circulation circuit,the controller hardware circuit and PCB board drawing,and design of the controller shell and the button panel,realize the function of the expected of variable-rate spraying control system.(3)The software control program and the upper computer program of the variable-rate spraying control system were developed.The upper computer software includes the airborne precise variable control software,the aerial application precision variable control device simulation software and the NCS position simulator software.The analog input of the GPS data to the controller is realized,and the simulation of the data communication between the airborne variable application controller and the onboard navigation terminal is completed.(4)The construction of the test platform for the manned helicopter airborne variable-rate spraying control system was completed,and the effectiveness,steady-state error and dynamic response of the system were tested respectively,and the test data was processed and analyzed.The test verified that the expected function of the helicopter airborne variable-rate spraying control system was normal,and the target application amount was in the range of 3.5 to 11.5 L/hm~2.The actual measured application amount was consistent with the target application amount,and the relative deviation was less than 5%.The actual application rate can quickly reach the target application amount,and the actual application rate fluctuates within 0.5 L/hm~2 of the target application rate during the process of changing the flight speed of the aircraft within the range of 90-160 km/h.It can meet the requirements of real-time adjustment of the application flow rate with the change of the speed of the aircraft,and meet the operation quality requirements of the application of the unit area in the working area.