小型无人机机载农药变量喷洒系统设计

基于脉宽调制（Pulse Width Modulation，PWM）技术设计小型无人机机载农药变量喷洒系统，主要由药箱、喷头、液泵及喷洒控制器组成，通过调整PWM 喷洒控制信号的占空比，改变液泵的工作时长，从而实现变量喷洒。基于常量喷洒流量指标和机载喷洒系统的覆盖范围，确定PWM 频率为1 Hz，并建立了该频率下占空比与喷洒流量之间的3 次多项式关系模型，模型决定系数达到0.9944。以关系模型为指导，分别测试了0.3、0.4、0.5 L/min 流量控制指标下的变量喷洒试验效果，喷洒值和目标值之间误差分别为8.66%、4.50%和1.60%，达到变量喷洒控制的目的。

Variable pesticide spraying system design based on small UAV

Based on PWM (Pulse Width Modulation) technology, the variable pesticide spraying system of UAV(Unmanned Aerial Vehicle) was promoted, which consisted of kits, nozzles, pump and spray controller. The pump operatingtime was varied by the duty cycle of the PWM signal, so as to change the spray flow. According to the constant flowindicators of spraying pesticides and the coverage sprinkler system, the PWM frequency was determined to 1 Hz. A cubicpolynomial relationship model between duty cycle and spray flow was established, and the coefficient of determinationreached 0.9944. Experiments under flow rate indicator condition of 0.3, 0.4 and 0.5 L/min were done, and the resultsshowed that the errors between sprayed and target flow were 8.66%, 4.50% and 1.60%. Variable spray control objectivewas achieved.