基于高度融合的植保无人机仿地飞行方法研究

多旋翼植保无人机在坡地作业过程中一般作业于作物上方1.5~3 m的近地空中,需要保持稳定的仿地飞行才能保障无人机的安全飞行和喷洒均匀性。提出了一种仿地飞行方法,通过前置毫米波雷达进行坡度判断,在坡度起伏较小时,将差分GPS高度与对地毫米波雷达高度进行卡尔曼滤波融合以提高精度,在坡度变化超出阈值时,将前置毫米波雷达与对地毫米波雷达的高度进行多雷达高度信息融合以提高响应速度,最后采用模糊PID控制算法控制无人机高度。通过仿真和实地飞行测试,实现了植保无人机坡地仿地飞行高度误差小于40 cm的目的,保证了无人机的环境适应能力和喷洒均匀性,为植保无人机在不同地形下的全自动作业奠定了基础。

Terrain Following Method of Plant Protection UAV Based on Height Fusion

Multi-rotor plant protection unmanned aerial vehicle (UAV) in sloping fields was usually operated at a height of 1.5~3m above the crops. The significance of the terrain following is that the height of the plant protection UAV above the crops do not change when the gradient of the terrain changes. The plant protection UAV needed to maintain a stable terrain following to ensure the safety of flight and spray uniformity. A terrain following method was proposed by using millimeter wave radar. The pre millimeter wave radar was used for slope judgment .When the slope was small, the height of the differential GPS and the height of the ground penetrating millimeter wave radar were filtered by Kalman filter, which can improve the accuracy. When the slope changed beyond the threshold,the height of the pre millimeter wave radar and ground penetrating millimeter wave radar were fused by multi-radar information fusion, which can improve the response speed. Then fuzzy PID algorithm was used to control the height of plant protection UAV. Through simulation and field flight test, the millimeter wave radar was accurate over the crops, and the height error of terrain following was less than 40cm. The results showed that the adaptability and the spray uniformity of the plant protection UAV in sloping fields were ensured. The research on terrain following laid a solid foundation for the automatic operation of the plant protection UAV under various terrains.