In modern society, it is essential to collect various information to build vast amount of data.. There are many ways of gathering information, but it is especially time-efficient to acquire information on a moving means such as an airplane or a satellite. In the case of a camera mounted on a platform such as an aircraft, the stable operation of the shooting time determines the quality of the image information.Therefore, it is more demanding than other platforms and it is necessary to block external vibrations. A camera installed on an aircraft is mounted on a frame with a gimbal structure for orientation and driving, and is composed of an optical module to acquire an image and to stabilize drive device.
In order to ensure stabilization of the gimbal structure, it is desirable to design such that the natural frequency of the optical equipment does not exist within the external vibration frequency. However, if the structure is unavoidable, the vibration characteristics of the structure should be optimized to the control band do. There are active and passive vibration isolator system for vibration reduction. Passive vibration isolator system do not need additional equipment compared to active type and can be placed in a narrow space with small weight. Passive vibration isolators are mainly made of rubber material. Rubber has viscoelastic behavior with both elastic and viscous properties, exhibits incompressible behavior, and has large deformability. The dynamic characteristics of this viscoelastic material, bear, are influenced by environmental factors such as operating temperature and load, thus indicating uncertain dynamic characteristics. Careful attention should be paid to the designer to extract these uncertain and variable rubber parameters. Therefore, it is important to accurately analyze static behavior and dynamic characteristics of rubber materials. Simulations are performed using mathematical models for analysis.
Typically, the results of this simulation model depend on parameters that are unclear when setting parameters and some of the computations that can not be measured. Particularly, even though the vibration damping material of the rubber material itself has the same shape, the characteristics of the vibration damping material itself are widely dispersed due to the manufacturing environment. Therefore, it is difficult to test with many samples to apply to the analysis. In this thesis, the process of identifying the dynamic parameters on the isolators using a simple pilot test and a finite element model of the camera system is presented. A pliot test equipment is built to put real environmental condition (e.g., ,temerature condition, heat flow condition, etc.) on the elastomeric isolator. Therefore, the characteristics of an elastomer identified on test are the dynamic values reflecting the temperature environment characteristic. In the process, 3dB method is introduced for fast and effective parameter identification. On matching the isolator model on FEA to the disturbance transfer model on statbilization control simulator, it is able to narrow the difference between the test and the real condition by using more reliable parameters.
항공용 EO/IR 카메라의 안정화 성능은 주로 2가지 요소로 인해 영향을 받는다. : 첫번째로 항공기로부터 카메라에 전달되는 진동이며, 두 번째는 카메라가 장착되어 있는 내부김발의 질량 불균형에 기인된 토크외란이다. 우선 카메라에 유입되는 진동을 줄이기 위해 방진구를 사용하는데 주로 사용되는 점탄성 방진구는 장착성이 용이하며, 가볍고 진동소산효과가 뛰어나 항공장비에 널리 적용된다. 점탄성 방진구의 동적특성은 주파수와 온도의 함수이다. 따라서, EO/IR 카메라 시스템을 제어하기 위해서는 방진구의 동적특성을 알기 위해 정확한 매개변수 식별이 필수적이다. 방진구의 매개변수는 시험과 유한요소 모델링을 통해 역으로 산출할 수 있다. 본 논문에서는 간단한 파일럿 시험과 유한요소해석을 통해 방진구의 동적매개변수를 식별하는 절차를 제시하였다. 여기서 사용한 파일럿 시험장치는 진동 및 온도 등의 실제 운용환경을 모사할 수 있도록 구성하여, 환경영향성이 포함된 동적매개변수가 된다. 매개변수 식별시 해석과 시험간의 오차를 줄이는데 용이한 3dB 기법을 사용하였다. 이 과장에서 산출된 매개변수값들은 안정화제어기의 외란전달모델의 매개변수와 매칭되며, 구성품단위의 해석 및 시험결과를 실제 환경에서 전체구성품 시험을 통해 검증하였다.
