基于改进LK光流的四旋翼无人机悬停技术研究

Research on Hovering Technology of Quadrotor UAV Based on Improved LK Optical Flow

随着无人机应用场景的不断拓展,在GPS信号不可靠时仍能精确定位是无人机发展要解决的难题。以四旋翼无人机为研究对象,针对传统LK光流法在实际应用中存在定位精度不高的缺点,采用一种用于精确估计的改进LK光流法。该方法针对光流传感器的有限运算能力,采用Shi-Tomasi角点检测算法和双线性差值法提高无人机定位精度和稳定性;在光流计算时,通过建立光流金字塔解决无人机运动产生的大位移问题,并对计算产生的FB误差进行补偿,提高计算精确度;利用无人机硬件平台在室内进行实际飞行验证。结果表明:这种改进的LK光流法定位精度高,在稳定光照条件下能进行精确定位悬停飞行,其定点精度大约为半径40 cm的圆形。

With the continuous expansion of UAV application scenarios,it is the difficult problem that UAV can still be accurately positioned without GPS.It needs to be solved in the development process of UAV.This paper takes the quadrotor UAV as research object.Because low positioning accuracy exists in the traditional LK optical flow method in the practical application,an improved LK optical flow method for precise hovering positioning is proposed.The method is used to solve the limited computing power of the optical flow sensor,that the Shi-Tomasi corner detection algorithm and the bilinear difference method are used to improve the positioning accuracy and stability of the UAV.In the calculation of the optical flow,the optical flow pyramid is used to solve the large displacement problems in UAV movement and the FB error generated in the calculation is compensated,thus improving the positioning accuracy.The actual flight is verified indoors on the UAV hardware platform.The results show that the improved LK optical flow method has high positioning accuracy of the hovering flight under illumination conditions.Its fixed point accuracy is approximately within the range of 40 cm radius.