| The vehicle-mounted image stabilization platform(VISP)is often used to carry precise photoelectric equipment for target imaging,tracking or aiming.During its movement following up with the vehicle,the VISP suffers complex vibrations,impact and motion disturbances.Therefore,the vibration isolation system mounted bwtween it a nd the vehicle should have very high performances of vibration isolation and posture stabilization.If the vibration isolation performance is insufficient,it will lead to blurred imaging,bad tracking precision and even equipment damage.If the posture stabilization performance is insufficient,the tracking and aiming response will be slow or even cause equipment collision.Aiming at the requirements of vibration suppression and posture stablization for the image stabilization platform,according to severe limitation of weight and layout space,this thesis carries out the design,prototype development and performance testing of vibration isolation system.Firstly,the structural characteristics and vibration isolation requirements of the VISP are introduced,and the key problems in design of the vibration isolation system for VISP are analyzed.Combining the constraints of layout space and weight,a novel irrotational displacement vibration isolation configuration is proposed,which adopting multiple spring-damper units in circular distribution.The stiffness and damping parameters are determined to satisfy the vibration transmissibility at key exciting frequency and the resonant frequency,The stiffness-damping parameters are matched.Secondly,according to the space constraints and the required stiffness and damping parameters,a compact vibration isolation module with a viscous damper embedded in the cylindrical coil spring is designed.Taking into acount the axial stiffness and radial stiffness,as well as strength and fatigue factors,the cylindrical spiral spring for the main support is designed.A viscous damper with very small size is designed,and experimental identification of the damping parameter is carried out.A flexible hinge structure utilizing leaf-spring which exbibits high axial stiffness and low tilt stiffness is designed to resolve the problem of axial space restriction between the two ends of the damper.According to the layout of the vibration isolation system for the VISP,a new configuration of 4-SSP irrotational displacement mechanism is proposed,and the modal analysis and optimization design of its key components are completed.The angular displacement error caused by the lower parallelogram mechanism and the upper guiding mechanism are analyzed,which can be used as guidance for manufacturing and assembling of the irrotational displacement mechanism.Finally,the dynamic model of vibration isolation system for the VISP is proposed,and the natural vibration characteristics and the transmissibility of vibration isolation system are simulated.The prototype of vibration isolation system is then developed,and experiments of the vibration isolation performance are completed.Experimental results show that the vertical and horizontal natural frequencies of the vibration isolation system are 3.7 Hz and 3.4 Hz,and the errors between the design and the experiments are 4.64% and 3.13%.The vertical resonance peak of the vibration isolation system is 4.2d B,and the transmissibility in the frequency domain of 20-500 Hz is below-20.2d B,which are better than the target requirements of 10 d B and-20 d B respectively.The horizontal resonance peak of the vibration isolation system is 12.2d B,and transmissibility in the frequency domain of 20-500 Hz is below-18.2d B,which are better than the target requirements of 14 d B and-14 d B.Experiments show that the vibration isolation system exhibits good performance in the working frequency domain.The proposed design method and the prototype of vibration isolation system for the VISP have established a good foundation for its engineering practice,and can also be applied to the vibration isolation of the airborne image stabilization platform. |
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