Mechanism Design For Mounted Aerial Photography Pod On Skids

As aircraft developing rapidly and aerial region below 600m of our country gradually opening, aerial photography has an abroad foreground. For example, aerial photography is widely using to obtain the scale of 1:500,1:1000 and 1:2000 of land information. However, because of low altitude vertical aerial photography would get photography with the smaller angle of inclination, the photography would be done the after process more easy and more high efficiency, there is a sufficient research on it. Low altitude vertical aerial photography system is a system which usually taken on low level aircraft, stabled the camera visual axis by stabilized platform, to let camera normal image. Because of light helicopters fly at low level relatively to more steady, more efficient and cheaper, and have a large useful payload, and have widely applied for the platform of low attitude of aerial photography system. But light helicopter have a cramped inner space, it need to fix photograph pod outside the plane, and pods could mostly mounted on retraction and release skids.This paper which is considered the feature of retraction and release skids and external disturbance affecting camera imagery has designed a parallel connection slide bar linkage to adapt the motion of retracting and releasing of skids, so that camera could normally take vertical aerial photography. And the paper is also made use of supporting by flexible poles to control external high frequency and large amplitude of vibration, to reduce the pod swing by vibration.In order to assure the angle of tilt and swing of photography system, for the first, this paper was fellow the rule of low altitude vertical aerial photography to run out the requirement of mounted mechanism design. For the second, design out 3D structure of fasten mechanism in Pro/E fellow the motion of retraction and release helicopter skids, and then build a mathematic model and do the static analysis for it. With the purpose of assuring tilt angle of low altitude vertical aerial photography at whole photograph process, then import 3D model to ADAMS that make a simulation model for it. so that simulate out variety curve of slide bar's length and inclination angle, be aware that the chose mechanism parameter and it's design angle change region of mounted mechanism miss the design requirement. Thereby, make parameterize for mounted mechanism correlate design variable.set optimization object function for angle of tilt and constraint condition on mounted mechanism, optimize tilt angle of mounted mechanism, tilt angle change at -0.5～0.5degree after optimization, mounted mechanism after optimize design reach design requirement.In order to find out swing angle of mounted mechanism design condition, simplify support of flexible poles of mounted mechanism for vibration model, do theory analysis and simulation solve for the changing of swing angle of photograph pod by external disturbance, discover simulation solve result of photograph pod swing angle and disturbance response in accord with theory analysis, and meet the design requirement.At last, fasten photography pod run a test in simulation of normal flying environment, then investigate the change of tilt and swing angle of design mechanism. Measure data display that the change of tilt and swing angle is in the region of low altitude vertical of aerial photography requirement. Compare the test with a task of low altitude vertical aerial photography in the certain area of Wuzhou, Guangxi province, assess the quality of aerial photography, especially on tilt and swing angle, mounted mechanism design is success fellow the assess data.This paper also point out deep design of mounted mechanism, which maybe consider the gap between the connection bar and using aerodynamics to simulate fly environment more reality, so that the design conclusion of adapt mechanism is more authority.