Vision Detection And Guidance Based On 3D Cooperative Target

Under the background that UAVs have been applied in more and more missions,greater autonomous demands have been placed on them.Owing to addition in occasions that UAVs are guided to a target and computer vision technology’s ability that obtain abundant target information,the UAVs’ vision-guided technology have attracted considerable attention.Considering about autonomous landing as a vital section in autonomous flight and the fact that UAVs’ visual landing guidance is a typical application of UAVs’ guidance,the paper introduced in the application that autonomous landing and takeoff of a miniature UAV and aimed at the problem that two-dimensional planar target provides limited visual information and the connection between visual technology and guidance control is in low degree,takes a further research on VTOL UAVs’ vision-guided technology.Firstly,the overall design of the visual guidance system is designed.According to the needs of UAVs’ automous landing,the visual guidance system with landing as a typical case is analyzed.And the definition of the relevant coordinate system and its mutual conversion relationship are given.Finally,the camera imaging model is described.Then,aiming at the problem of limited visual information provided by two-dimensional planer taeget,a new three-dimensional cooperative target is designed as the landing target of the VTOL UAV,which can provide visual system with the third dimensional information in addition to the two-dimensional information,such as the target height.At the same time,this paper designed a set of visual detection algorithm with robustness and real-time ability.First of all,the target region is segmented in the complex background image,then the target feature informantion is extracted from the target region of the image,the influence of the background region on the target feature extraction is avoided.And the Hough transform circle detection algorithm is improved to reduce the computational complexity.Finally,combined with the known information of the three-dimensional cooperation target,the movement information needed for landing guidance and PTZ tracking-pointing is calculated.After that,considering the influence of the landing guidance scheme on the landing trajectory,the "parabolic" landing trajectory of the subject group is adopted,and the guiding scheme is improved to improve the influence of the self-stabilizing PTZ to isolate the body motion.And through the PTZ tracking-pointing control to ensure that the camera axis always point to the target center.At the same time,a new visual landing guidance scheme is proposed,which combines the visual technology with the guidance control effectively.The angle of the target line of sight of the visual detection system is taken as the controlled quantity,and the controller can change the speed of the body to achieve the control of the target line of sight control,so that the UAV can be in accordance with the desired landing trajectory.Finally,the whole system simulation verification of the visual landing guidance system is carried out to prove the effectiveness of the combination of visual technology and guidance control.And the system embedded platform is built.The visual detection Algorithm and PTZ tracking-pointing control are implemented in the embedded platform to verify the effectiveness of visual detection Algorithm and the PTZ tracking-pointing control.