Satellite Vibration Research Articles

Assessment of Electrical Influence of Multiple Piezoelectric Transducers' Connection on Actual Satellite Vibration Suppression

We conduct comprehensive investigation of a semiactive vibration suppression method using piezoelectric transducers attached to structures. In our system, piezoelectric transducers are connected to an electric circuit composed of the diodes, an inductance, and a selective switch. Our method (SSDI) makes better use of counterelectromotive force to suppress the vibration, instead of simple dissipation of vibration energy. We use an actual artificial satellite to verify their high performance compared to conventional semi-active methods. As a consequence, we demonstrate that our semi-active switching method can suppress the vibration of the real artificial satellite to as much as 50% amplitude reduction. In our experiment, we reveal that the suppression performance depends on how multiple piezoelectric transducers are connected, namely, their series or parallel connection. We draw two major conclusions from theoretical analysis and experiment, for constructing effective semi-active controller using piezoelectric transducers. This paper clearly proves that the performance of the method is the connection (series or parallel) of multiple piezoelectric transducers and the their resistances dependent on frequency.

A New Approach to Vibration Reduction Analysis Using Thin Polyimide Tape Inserted between Structural Elements

An effective countermeasure against vibration under limitation of volume and weight of small satellites is to insert thin polyimide tape between structural elements, especially for structural vibration of a small satellite during its launch. In this study, we deal with three types of aluminum elastic beams clamped on an aluminum rigid base. To explain dynamic damping properties of thin polyimide tapes inserted between structural elements based on our experimental data, we first develop a mathematical model, which can be applied to FEM analysis. Although this model generally depends on both the number of laminated tape layers and frequency, it shall be modified to a special model, which only depends on frequency but not depend on the number of layers. Finally, using a new test beam, the validity of the proposed mathematical model is demonstrated.

소형 복합재위성의 스팩트럼 및 과도진동해석

본 논문은 국내 최초의 소형 복합재 위성인 과학기술위성3호의 proto 모델에 대하여 랜덤, 정현파, 충격 진동응답에 대한 연구이다. 과학기술위성3호의 구조체는 여러 장의 패널을 서로 연결하여 만든 박스형의 구조이며 패널은 탄소섬유강화 복합재를 적층한 스킨에 알루미늄 허니컴 구조를 접착한 하이브리드샌드위치구조로 되어있다. 상용 FEA 코드인 MSC/NASTRAN을 사용하여 주파수 및 시간영역에서 위성의 설계요구조건으로 주어진 진동시험수준에 대한 모드, 응력, 변위, 가속도의 응답을 계산하였다. 이러한 해석결과를 바탕으로 발사 시 야기되는 진동으로 인한 파괴, 안전율 및 설계 타당성을 검토하였다. 이 연구결과들은 실제 위성구조설계 신뢰성 실험에 있어서 검증 및 비교의 자료로 사용될 수 있고, 위성개발의 중요한 자료로 활용된다. This paper is the study on random, sinusoidal and shock vibration responses for the STSAT-3(science and technology satellite-3) proto-model which is the first small size all-composite satellite in Korea. The structure system of the STSAT-3 forms box type structure by joining several hybrid sandwich panels comprised of honeycomb core and carbon fiber reinforced laminated composite skins on both side. Mode shape, stress, displacement and acceleration responses are obtained on both the frequency domain and time domain by means of a commercial FEA software MSC/NASTRAN. From these analysis results, failure, safety factor and design validity are assessed. These results can be successfully applicable as reference data when a new satellite is developed as well as giving out an excellent criteria in satellite vibration treatment design.

人工衛星の指向精度と振動・制御(OS-3 基調講演)

人工衛星の指向精度と振動・制御(OS-3 基調講演)

In orbit nano-g measurements, lessons for future space missions

The electrostatic space accelerometers mounted on board the three satellites of the two last geodesy missions, CHAMP [C. Reiberg, CHAMP a challenging micro-satellite payload for geophysical research and application, GFZ Final Report, Potsdam, Germany, 1995] and GRACE [E. Davis, et al., The GRACE Mission: Meeting the Technical Challenges, 50th International Astronautical Congress, IAF-99-B.2.05 Conference, AAS 90-034, 1999], respectively launched in 2000 and 2002, take continuous and accurate measurements of the satellite drag acceleration. At the altitude between 400 and 500 km, this drag is induced by the residual atmosphere and the Sun and Earth radiation pressures. With a resolution up to several pico-g, these data provide also a good survey of the satellite vibration behaviour and of the operation of the attitude and orbit control. Beside the scientific interest of both missions with the fine and global recovery of the Earth's gravity field, the analysis of the collected acceleration data is very interesting for the future space missions like GOCE [ESA, Gravity Field and Steady-State Ocean Circulation Mission, ESA SP-1233(1), Report for mission selection of the four candidate earth explorer missions, European Space Agency, 1999, p. 217], MICROSCOPE [P. Touboul, et al., C. R. Acad. Sci. Ser. IV 2 (9) (2001) 1271–1286] or LISA [LISA Study Team, LISA Laser Interferometer Space Antenna: a Cornerstone Mission for the Observation of Gravitational Waves, ESA-SCI(2000)11, European Space Agency, 2000] which envisage much more accurate acceleration measurements. The definitions of these missions and others in the domain of fundamental physics and solid Earth are all based on drag-free satellites and similar electrostatic inertial sensors. Benefits of the previous results are presented in parallel to the status of these developments.

In orbit nano-g measurements, lessons for future space missions

The electrostatic space accelerometers mounted on board the three satellites of the two last geodesy missions, CHAMP [C. Reiberg, CHAMP a challenging micro-satellite payload for geophysical research and application, GFZ Final Report, Potsdam, Germany, 1995] and GRACE [E. Davis, et al., The GRACE Mission: Meeting the Technical Challenges, 50th International Astronautical Congress, IAF-99-B.2.05 Conference, AAS 90-034, 1999], respectively launched in 2000 and 2002, take continuous and accurate measurements of the satellite drag acceleration. At the altitude between 400 and 500 km, this drag is induced by the residual atmosphere and the Sun and Earth radiation pressures. With a resolution up to several pico-g, these data provide also a good survey of the satellite vibration behaviour and of the operation of the attitude and orbit control. Beside the scientific interest of both missions with the fine and global recovery of the Earth's gravity field, the analysis of the collected acceleration data is very interesting for the future space missions like GOCE [ESA, Gravity Field and Steady-State Ocean Circulation Mission, ESA SP-1233(1), Report for mission selection of the four candidate earth explorer missions, European Space Agency, 1999, p. 217], MICROSCOPE [P. Touboul, et al., C. R. Acad. Sci. Ser. IV 2 (9) (2001) 1271–1286] or LISA [LISA Study Team, LISA Laser Interferometer Space Antenna: a Cornerstone Mission for the Observation of Gravitational Waves, ESA-SCI(2000)11, European Space Agency, 2000] which envisage much more accurate acceleration measurements. The definitions of these missions and others in the domain of fundamental physics and solid Earth are all based on drag-free satellites and similar electrostatic inertial sensors. Benefits of the previous results are presented in parallel to the status of these developments.

Analysis of an optical satellite communication system with stabilized microwave reference note transmission

AbstractA new optical satellite communication system with a local oscillator in the transmitter and one in the receiver station is presented. A new microwave–photonic receiver for picking up the stabilized microwave reference note is proposed. The system, which transmits a 2.5‐Gbps FSK signal, is analyzed. Satellite vibration, beam divergence, atmosphere absorption, and scattering are considered. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 149–151, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10260

Use of satellite natural vibrations to improve performance of free-space satellite laser communication

In some of the future laser communication satellites, it is plausible to assume that tracking and communication receivers will use the same detector array. The reason for dual use of the detector is to design simpler and less expensive satellites. Satellites vibrate continually because of their subsystems and environmental sources. The vibrations cause nonuniform spreading of the received energy on the detector array. In view of this, the information from the tracking system is used to adapt individually the communication signal gain of each of the detectors in the array. This adaptation of the gains improves communication system performance. It is important to emphasize that the communication performance improvement is achieved only by gain adaptation. Any additional vibrations decrease the tracking and laser pointing system performances, which decrease the return communication performances (two-way communication). A comparison of practical communication systems is presented. The novelty of this research is the utilization of natural satellite vibrations to improve the communication system performance.

Vibrations of the Low Power Atmospheric Compensation Experiment satellite

The Low Power Atmospheric Compensation (LACE) satellite dynamics experiment has measured vibrations of an orbiting satellite from a ground site and has observed the excitation of satellite vibrations by a sequence of boom movements. The preprogrammed boom movements were initiated by commands from a ground control site and observed by the Massachusetts Institute of Technology Lincoln Laboratory Firepond laser radar facility located in Westford, Massachusetts. In the tests, a narrow-band heterodyne COi laser radar, operating at a wavelength of 10.6 /Ltm, detected vibration-induced differential Doppler signatures of the LACE satellite. Augmentation of vibration amplitudes was achieved through timing of repeated boom movements. Evidence of open-loop vibration damping by this method of repeated boom movements was also obtained, although the data were not conclusive since only a single attempt at open-loop damping was observed. The tests have demonstrated the feasibility and advantages of using relatively low cost ground-based observation techniques for vibration measurements and health monitoring of orbiting structures and for improving the accuracy of mathematical models for the structural dynamics of light, flexible space structures.

Satellite vibration measurements with an autodyne CO_2 laser radar

Vibration signatures of the Low Power Atmospheric Compensation Experiment satellite were obtained with a ground-based CO(2) laser radar. The laser radar operated in a cw mode and used autodyne receivers to extract relative target velocity information between a germanium retroreflector located at the base of the satellite and a retroreflector array located at the tip of an extended forward boom. Time-frequency analysis algorithms were applied to the vibration data to investigate the correlation between excitations and modal structure. The resultant analysis suggests that vibration modes of an on-orbit spacecraft can be suppressed with simple open-loop techniques.

Ground-based laser radar measurements of satellite vibrations

Vibration signatures from the low-power atmospheric compensation (LACE) satellite are obtained by using the MIT Lincoln Laboratory Firepond coherent CO(2) laser radar facility located in Westford, Mass. The LACE satellite is equipped with IR germanium retroreflectors on deployable/retractable booms to enhance ground-based IR laser radar measurements of on-orbit boom vibrations. Analysis of pulsed cw laser radar measurements of the satellite during and subsequent to boom retraction indicates the presence of a complex time-varying model structure. The observed vibration spectra include vibration modes not previously predicted. These data represent the first observations of satellite vibration modes from a ground-based laser radar.

The SILEX optical interorbit link experiment

The implementation of communication links between a low earth-orbiting satellite and a geostationary one, or between two geostationary satellites, will lead to significant improvements in the performance of space communication systems. Optical technology is attractive for these applications when high-data-rateCommunication is required. The European Space Agency (ESA) has therefore instigated and in-ordbit demonstration project known as SILEX (semiconductor laser intersatellite link experiment) using a pre-operational link between the French SPOT-4 low earth orbit satellite and the ESA Advanced Relay and Technology Mission Satellite(ARTEMIS). Such and optical communication system brings some new and challenging requirements. In particular, the communication beam, which has a divergence of around 6 μrad, must achieve and maintain a very demanding pointing accuracy in the presence of both host satellite vibration and relative satellite motion. This paper provides an overview of the SILEX project and describes a novel pointing mechanism.