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Attitude Estimation and Control of Satellite Using Noisy Measurements

Firoozi, Dena | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42541 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Namvar, Mehrzad
  7. Abstract:
  8. Satellite attitude determination means specifying its rotation relative to a known reference. To determine satellite attitude, gyroscope is used to measure angular velocity and attitude sensors such as sun sensor, magnetometer, star tracker and earth horizon scanner are used in order to obtain vector measurements. In kinematic control, satellite angular velocity is determined in a way that its attitude converges to desired attitude. Usually, gyroscope and attitude sensors measurements are contaminated by noise which leads to errors in satellite attitude estimation and control. In the literature, gyroscope and at least two vector meaurements are used to estimate and control the satellite attitude. While, in some cases especially for small satellites with limited ?nancial, power and mass budget, it is optimal to use gyroscope and only one vector measurement. In addition, developing an algorithm which uses only one attitude sensor measurement increases the reliability of ADCSa remarkably in the case of sensor failures. recently, some attitude estimation and control algorithms has been proposed which use gyroscope and one vector measurement. But, in these works it is assumed that all sensors are ideal. In fact, the e?ect of measurement noise is neglected. In this thesis, in the ?rst step it is assumed that gyroscope output contains noise and two approches for noise analysis of an attitude estimation algorithm which uses gyro and only one vector measurement are presented. In the ?rst approach which is called stochastic analysis, we assume that noise distribution and its statistical properties such as its mean and variance are known. However, statistical properties of noise are not available often and these assumptions may not be satis?ed in reality. In the second approach which is called deterministic analysis, we do not consider any special distribution for noise and just assume that noise upperbound is known. Often, noise upperbound in usuall engineering applications is available. In addition, a method for tunning observer gain in a way that minimizes estimation error in the existence of gyro noise is proposed. In the second step, the e?ect of uncertainty in the attitude sensor measurement on estimation algorithm is investigated and deterministic analysis is presented. In the third step, the proposed analyses are applied to the kinematic control algorithm of satellite. The innovation of this thesis is in the proposition of stochastic and determinestic noise analysis for sensors measurements in an attitude estimation and a control algorithm which use gyro and only one vector measuremen
  9. Keywords:
  10. Satellite Attitude Control ; Attitude Estimation ; Attitude Control ; Gyroscope ; Measurement Noise

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