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Fig. 3. Block diagram of the proposed pico satellite attitude determination and control system. On the other hand, although magnetometers’ constant bias terms are estimated initially, they may vary by time because of some unexpected factors and

Figure 3 Block diagram of the proposed pico satellite attitude determination and control system. On the other hand, although magnetometers’ constant bias terms are estimated initially, they may vary by time because of some unexpected factors and

Related Figures (7)

Fig. 1. In flight calibration scheme for magnetometers. For the first stage of the estimation, where the magnetometer biases are estimated as well as the atti- tude angles and attitude rates, the estimated state is formed as given in (1) and at that stage it is assumed that gyros are bias free since they are working accu- rately at that initial phase after the orbit injection. The architectural scheme is given as Fig. 1.
Fig. 1. In flight calibration scheme for magnetometers. For the first stage of the estimation, where the magnetometer biases are estimated as well as the atti- tude angles and attitude rates, the estimated state is formed as given in (1) and at that stage it is assumed that gyros are bias free since they are working accu- rately at that initial phase after the orbit injection. The architectural scheme is given as Fig. 1.
Fig. 2. In flight calibration scheme for gyros. As mentioned previously, at the second stage of the estimation procedure the gyro biases are estimated. At that stage, previously estimated magnetometer bias terms are taken into consideration and the algorithm is run for the estimation process of the gyro bias terms which have become larger by time (not negligible anymore). The estimated state is formed as given in (2).
Fig. 2. In flight calibration scheme for gyros. As mentioned previously, at the second stage of the estimation procedure the gyro biases are estimated. At that stage, previously estimated magnetometer bias terms are taken into consideration and the algorithm is run for the estimation process of the gyro bias terms which have become larger by time (not negligible anymore). The estimated state is formed as given in (2).
Fig. 4. Magnetometer bias estimation for the magnetometer 6699 aligned in the “x” axis.
Fig. 4. Magnetometer bias estimation for the magnetometer 6699 aligned in the “x” axis.
“oy? Fig. 5. Gyro bias estimation for the gyro aligned in the axis.
“oy? Fig. 5. Gyro bias estimation for the gyro aligned in the axis.
6699 Fig. 7. Estimation of the angular rate about “x” axis. in Figs 6 and 7. It is obvious that attitude angles and the attitude rates of the satellite can also be accurately esti- mated by the proposed two stage estimation scenario. Note that similar results are obtained for all other atti- tude angles and the attitude rates.
6699 Fig. 7. Estimation of the angular rate about “x” axis. in Figs 6 and 7. It is obvious that attitude angles and the attitude rates of the satellite can also be accurately esti- mated by the proposed two stage estimation scenario. Note that similar results are obtained for all other atti- tude angles and the attitude rates.
Fig. 6. Pitch angle estimation.
Fig. 6. Pitch angle estimation.
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