Robust corner precise detection algorithm for visual landing navigation of UAV

A robust corner precise detection algorithm is proposed to solve the problem that the images have a serious distortion of scale and angle when the carrier-based unmanned helicopter lands. A cooperation with distinct color contrast and asymmetric is designed. And corners on the cooperative object can be gotten through calculating the minimum perimeter polygon (MPP) of the cooperative object. To solve the problem of removing false corners and corners out of order, a strategy which concludes slope constrain, distance constrain and orientation constrain is proposed. Finally, to solve the problem of the sub pixel Harris corner detection algorithm with high precision but out of order and the MPP corner detection algorithm based on triple constraints with low precision but ordered, a fusion strategy is proposed. Experiment results show that the proposed fusion algorithm can effectively solve the problem of corner detection when cooperation has a serious distortion of angle and a certain range of scale distortion.