Passive damping and vibration test of airborne stable pods for power line inspection using helicopters

Abstract

An airborne optoelectronic stable pod is mounted on a helicopter by pylons. The pod suppresses the impact of strong vibration and large swaying of the aircraft to stabilize the optical axis of the camera and to produce high-definition images under dynamic conditions. First, a passive damping system comprising a mechanical turntable with two axes and four frames for a photoelectronic stable pod is designed. Then the pod’s vibration reduction performance is tested. Additional tests are performed on the vibration of the helicopter and the pylon under flight conditions during the actual power line inspection, test the stabilization precision and imaging effect of the pod under flight conditions. The test results are analysed in detail, and the pod’s stability performances are verified under airborne conditions. The stability precision of the pod is better than 30 μrad (1σ), and a pin of 3-mm diameter can be clearly shot during aircraft hovering. The vibration test shows the pylons do not amplify the vibration of the aircraft while meeting stiffness requirement.