• Title/Summary/Keyword: Small CMG

Search Result 11, Processing Time 0.025 seconds

Agile Attitude Control of Small Satellite using 5Nm Small CMG (5Nm급 소형 CMG를 이용한 소형위성 고기동 자세제어)

  • Rhee, Seung-Wu;Seo, Hyun-Ho;Yoon, Hyung-Joo
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.46 no.11
    • /
    • pp.952-960
    • /
    • 2018
  • Recently, lots of remote sensing satellite require agility to collect more images within the limited time frame. To satisfy this kind of mission requirement, high torque actuator such as CMG is an essential element. In this study, 5Nm class small CMG developed by KARI is introduced to implement for an agile small satellite design. One of the singularity escape CMG steering law, Designated Direction Escape (DDE) method, which is a sort of modified version of Singular Direction Avoidance (SDA) method is summarized for its application on the numerical simulation of agile attitude control system design result. The performance of DDE method is demonstrated properly by escaping well known elliptic internal singularity successfully. 5Nm class small CMG cluster in a pyramid type as well as a roof type configuration is utilized to perform the numerical simulation and to demonstrate its agility design result for a small satellite. Simulation result shows the properness of 5Nm small CMG to a small agile satellite system. Also, the simulation result provides some valuable information that is important to CMG hardware design and manufacturing.

Low Cost Small CMG Performance Test and Analysis (저가 소형 CMG 성능시험 및 분석)

  • Rhee, Seung-Wu;Kwon, Hyoek-Jin
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.39 no.6
    • /
    • pp.543-552
    • /
    • 2011
  • Control Moment Gyro(CMG) is one of the most efficient momentum exchange devices for satellite attitude control and CMG is very essential device for agile satellite. In this study, the essential dynamic equation for the design of gimbal motor and wheel motor is summarized. The development process of SGCMG hardware for agile small satellite system, the description of developed hardware and its performance test results are presented. Test result shows that the developed hardware model can produce an output torque more than 1.2Nm as designed. Other test items are max. torque, gimbal bandwidth, minimum torque, torque error, gimbal rate error.

Development of 0.6Nm Small CMG Hardware and Performance Test (0.6Nm급 소형 CMG 하드웨어 개발 및 성능시험)

  • Jang, Woo-Young;Rhee, Seung-Wu;Kwon, Hyoek-Jin
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.38 no.9
    • /
    • pp.933-942
    • /
    • 2010
  • Control Moment Gyro(CMG) is one of the most efficient momentum exchange devices for satellite attitude control and CMG is very essential device for agile satellite. And the studies of CMG development and its application to satellite have been done extensively. In this study, the development process of SGCMG hardware for agile small satellite system, the developed hardware and its performance test results are presented. As a SGCMG test results, it is verified that the developed hardware model can produce torque more than 0.6Nm as is designed. By investigating its test data results, the issues that should be considered for the performance improvement and its application are discussed. The remedies for the identified issues are proposed for future study.

c-CMG Cluster for Small Satellites

  • Lee, Seung-Mok;Seo, Hyun-Ho;Rhee, Seung-Wu
    • International Journal of Aeronautical and Space Sciences
    • /
    • v.8 no.1
    • /
    • pp.105-114
    • /
    • 2007
  • This article presents the details of a designed control moment gyroscope (CMG) with a constant speed momentum wheel and one-axis-gimbal, and its experimental results performed at Korea Aerospace Research Institute. The CMG which is able to produce a torque of lOO mNm per each, is mounted in a pyramid configuration with four SGCMGs. Each CMG test and a single axis maneuver test with four-CMG cluster configuration are performed to confirm their performance on a ground-test facilities consisted of three major parts: a vibration isolation system, a dynamic force plate (Kistler sensor), and a DSP board. These facilities provide the accurate data of three axial and torques from the control moment gyro. Details of the CMG experimental results are presented with discussion of the experimental errors. The experimental data are compared with theoretical results and both results are used to verify their performance specifications.

Highly Agile Actuator Development Status of an 800 mNm Control Moment Gyro (CMG)

  • Goo-Hwan Shin;Hyosang Yoon;Hyeongcheol Kim;Dong-Soo Choi;Jae-Suk Lee;Young-Ho Shin;Eunji Lee
    • Journal of Space Technology and Applications
    • /
    • v.3 no.4
    • /
    • pp.322-332
    • /
    • 2023
  • Satellite attitude-control actuators are equipped with a reaction wheel for three-axis attitude control. The reaction wheel rotates a motor inside the actuator to generate torque in the vector direction. When using the reaction wheel, there are restrictions on the torque values generated as the motor rotates. The torque value of the reaction wheels mounted on small satellites is approximately 10 mNm, and high values are not used. Therefore, three-axis attitude control of a small satellite is possible using a reaction wheel, but this method is not suitable for missions that require rapid attitude control at a specific time. As a technology to overcome the small torque value of the reaction wheel, the control moment gyro (CMG) is currently in wide use as a rapid attitude-control actuator in space satellites. The CMG has an internal gimbal mounted at a right angle to the rotation motor and generates a large torque value. In general, when the gimbal operates, a torque value approximately 100 times greater is generated, making it suitable for rapid posture maneuvering. Currently, we are developing a technology for mounting a controlled moment gyro on a small satellite, and here we share the development status of an 800 mNm CMG.

Dynamics Modeling and Vibration Analysis of Momentum Wheel for the Control Moment Gyros (제어모멘트자이로용 모멘텀휠의 동역학모델링과 진동분석)

  • Park, Jongoh;Myung, Hyunsam;Lee, Henzeh;Bang, Hyochoong;Choo, Yeongyu
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
    • /
    • 2009.05a
    • /
    • pp.180-185
    • /
    • 2009
  • Actuator-induced disturbance is one of the crucial factors of spacecraft attitude pointing and stability in fine attitude control problems. The control moment gyros (CMGs) are known as very attractive actuators from the point of high power and low weight. In order to develop a CMG as an actuator for fine controls, CMG-induced disturbances should be analyzed. Therefore, this paper aims to develop an analytic model and predict the effect of disturbances of CMGs by assuming static and dynamic imbalances. The proposed model is induced by the Lagrangian method on the basis of the small signal assumption. In this research, mechanical system of the CMG is designed and the main components of CMG are producted.

  • PDF

Chinese Medicine Granule Affects the Absorption and Transport of Glucose in Porcine Small Intestinal Brush Border Membrane Vesicles under Heat Stress

  • Song, Xiaozhen;Xu, Jianqin;Wang, Tian;Liu, Fenghua
    • Asian-Australasian Journal of Animal Sciences
    • /
    • v.22 no.2
    • /
    • pp.246-253
    • /
    • 2009
  • This study was conducted to investigate the effects of Chinese medicine granule (CMG, including Cortex Phellodendron, Atractylodes Rhizome, Agastache Rugosa and Gypsum Fibrosum) on absorption and transport of glucose in porcine small intestinal brush border membrane vesicles (BBMVs) under heat stress. Forty-eight 2-month-old Chinese experimental barrows were screened according to weight and litter origin, and then allotted to three groups and treated as follows: Normal temperature control group (NTCG; $23^{\circ}C$), high temperature control group (HTCG; $26^{\circ}C$ for 19 h, $40^{\circ}C$ for 5 h); Chinese medicine granule anti-stress group (CMGG; $26^{\circ}C$ for 19 h, $40^{\circ}C$ for 5 h) (n = 16 per group). The results showed that high temperature treatment decreased (p<0.05) the growth performance and intestinal glucose absorption but there was no change (p>0.05) in the expression of SGLT1 and GLUT2 genes in the small intestine of pigs compared with the NTCG. Dietary supplementation with CMG improved the growth performance, and increased the activity of disaccharidases in duodenum and jejunum of heat stressed pigs (p<0.05). CMG treatment increased (p<0.05) the protein levels of SGLT1 and GLUT2 in the small intestine, and up-regulated (p<0.05) the expression of SGLT1 and GLUT2 genes in the duodenum and jejunum but without changing (p>0.05) them in the ileum compared with the HTCG. These results indicated that CMG treatment significantly improved porcine growth performance, and increased intestinal glucose absorption and transport by BBMVs under heat stress, in addition to up-regulating the expression of SGLT1 and GLUT2 genes in porcine duodenum and jejunum.

Analytic Modeling of Control Moment Gyros (인공위성 자세제어를 위한 제어 모멘트 자이로의 정밀 모델링)

  • Myung, Hyun-Sam;Lee, Hen-Zeh;Park, Jong-Oh;Bang, Hyo-Choong;Oh, Shi-Hwan;Yong, Ki-Lyuk
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.35 no.7
    • /
    • pp.640-646
    • /
    • 2007
  • Actuator-induced disturbance is one of the crucial factors of spacecraft attitude pointing and stability in fine attitude control problems. The control moment gyros (CMGs) are known as very attractive actuators from the point of high power and low weight. In order to develop a CMG as an actuator for fine controls, CMG-induced disturbances should be analyzed. Therefore, this paper aims to develop an analytic model and predict the effect of disturbances of CMGs by assuming static and dynamic imbalances. The proposed model is induced by the Lagrangian method on the basis of the small signal assumption.

Numerical Simulation for Diffusion and Movement of Air Pollutants in Atmospheric Flow Coastal Urban Region (연안도시지역의 대기유동장에서 대기오염물질의 확산과 이동에 관한 수치모의)

  • 이화운;김유근
    • Journal of Environmental Science International
    • /
    • v.6 no.5
    • /
    • pp.437-449
    • /
    • 1997
  • To predict diffusion and movement of k pollutants In coastal urban region a numerical simulation shouts be consider atmospheric flow field with land-sea breeze, mountain-valley wand and urban effects. In this study we used Lagrangian [article dispersion method In the atmospheric flow field of Pusan coastal region to depict diffusion and movement of the Pollutants emoted from particular sources and employed two grid system, one for large scale calculating region with the coarse mesh grid (CMG) and the other for the small region with the One mesh 914 (FMG). It was found that the dispersion pattern of the pollutants followed local circulation system in coastal urban area and wale air pollutants exhausted from Sasang moved Into Baekyang and Jang moutain, air pollutants from Janglim moved into Hwameong-dong region.

  • PDF

Simulation of Atmospheric Pollutants Concentration in the Urban Scale (도시 규모의 대기오염 농도 예측)

  • 이상득;정일현
    • Journal of Korean Society for Atmospheric Environment
    • /
    • v.13 no.2
    • /
    • pp.137-145
    • /
    • 1997
  • To predict the effects of air pollutant in the coastal region, we have developed the air pollutant model, the reaction model and the deposition of NO, $NO_2, and O_3$. And the numerical model of air pollutant concentration employed the nested technique to calculate with the higher resolution for the area. The nested technique used two grid systems, one for the large scale calculating region with the coarse mesh grid (CMG) and the other for the small scale region with the fine grid (FMG). In other to prove the validity of the simulation model the calculations were conducted for the present situation. The results of them reasonably agree with the observed data and proved the validity of the model.

  • PDF