Design And Dynamics Analysis Of Airborne Camera Vibration Isolation Platform

The airborne photographic vibration isolation platform is used in the film and television shooting industry,and its performance has a significant impact on the quality of photographic images.The camera system not only withstands the high-frequency vibrations generated by the aircraft engine,but also withstands the medium and high-frequency vibrations caused by the turbulence of the airflow,as well as the low-frequency vibrations caused by the aircraft attitude changes.Traditional wire rope vibration isolators mainly isolate high-frequency vibration,while pneumatic dampers can better solve the problem of low-frequency vibration.Therefore,this paper adopts a vibration isolation idea of parallel coupling of wire rope vibration isolators and pneumatic dampers to conduct a photographic vibration isolation platform.The structure design,performance simulation and experimental research are discussed.The specific work completed includes:First,based on the airborne vibration characteristics and the development and research status of airborne vibration isolation technology,a hybrid vibration isolation scheme consisting of wire rope vibration isolators and adjustable pneumatic dampers in parallel is adopted.Secondly,the mechanical model of the wire rope isolator is established based on the consideration of the three-directional nonlinear stiffness of the wire rope isolator,the two-way nonlinear Coulomb friction force in tension,the three-dimensional nonlinear damping force,and the simplified torsional stiffness.The theory of viscous fluid mechanics establishes the mechanical model of adjustable pneumatic dampers with fixed cylinder diameter,multiple small holes for flow,and adjustment of the diameter of the flow hole.A vibration model of an airborne photographic vibration isolation platform coupled in parallel with multiple wire rope vibration isolators and multiple pneumatic dampers is established.Then,the free vibration and the forced vibration of different frequency bands and different amplitudes of the vibration isolation platform acting alone by the wire rope vibration isolator are studied.The simulation program for the displacement,velocity and acceleration time response of the vibration isolation object under the parallel coupling of the wire rope vibration isolator and the pneumatic damper is written.The free vibration of the wire rope-pneumatic damping coupling vibration isolation platform and the forced vibration of different frequency bands and different amplitudes are studied.The simulation optimization analysis is carried out for the case of the aerodynamic damper with orifices.The active adjustment of the damping of the pneumatic damper,that is,the adjustment of the diameter of the small hole,is studied.The simulation results show that the vibration isolation performance of the wire rope-pneumatic damping coupling isolation platform is significantly better than that of the isolation platform with a wire rope acting alone.The attenuation rate of displacement amplitude is increased by 96%during free vibration,and the amplitude at the resonance frequency is attenuated by 81.3%during excitation vibration.The wire rope-pneumatic damping coupling vibration isolation platform not only improves the vibration isolation performance of the vibration isolation system at low frequencies,but also broadens the vibration isolation frequency band of the vibration isolation system.When the pneumatic damper has orifices,the smaller the number of damping holes,the better the damping performance of the damper;the smaller the diameter of the damping hole,the better the performance of the damper,but the longer the response time to reach the equilibrium position.The dynamic adjustment of the damping characteristics should be based on the adjustment of the displacement curve,which is easy to adjust and has good performance.Compared with the fixed orifice diameter,the vibration isolation effect is increased by 60%.Finally,according to the conclusions of simulation optimization and considering the characteristics of light weight and compactness of the airborne,the overall structure of the vibration isolation platform with four sets of wire rope vibration isolators and four sets of pneumatic dampers in parallel is designed.Set up an experimental platform for the airborne photographic vibration isolation system,install high-frequency acceleration sensors in three directions,and the vibration response test of the wire rope vibration isolator and the wire rope-pneumatic damping coupling vibration isolator under free vibration and road disturbance excitation vibration.The experimental results display that the vibration isolation effect of the wire rope-pneumatic damping parallel coupled vibration isolation platform is better,and the vibration isolation effect of the wire rope-pneumatic damping parallel coupled vibration isolation platform during free vibration is 59.8%higher than that of the wire rope alone.Compared with the vibration isolation platform when the vibration is excited,the vibration isolation effect is improved by 61.5%in the vertical direction and 42%in the horizontal direction.