中文摘要：

六旋翼无人机应用于植保领域时通常需要定高飞行,单一机载微传感器无法长时间准确的跟踪六旋翼无人机的高度,且当负载发生变化时无人机的高度控制会出现不稳定现象。针对上述问题,本文采用了一种基于气压计和加速度计卡尔曼滤波融合的高度测量系统,并设计了一个双闭环PID控制加前馈控制的高度控制器,最终获得了无人机飞行高度的精确估计与稳定控制。实验结果表明,经过卡尔曼滤波可以得到准确、平稳的高度值和速度值。提出的高度控制器在变载荷情况下也能很好的控制无人机的高度。

英文摘要：

Six-rotor UAVs usually require constant altitude flight when applied in plant protection, as we know the UAV altitude could not be tracked by a single airborne micro-sensor and that the altitude-hold would be unstable in the case of loads of the UAVs are changed. Aiming to solve these problems, a novel system based on barometer and accelerometer Kalman filtering fusion is proposed for altitude measuring, and also a controller based on double- closed-loop PID and feedforward controller is designed for altitude-hold. As a result,we obtain the accurate altitude- estimation and the stable control of the UAVs. Results of the experiment show thatthe value of altitude and velocity could be more accurate and steady by Kalman filtering. And the altitude-controller has a good performance under the condition of changing load