Attitude determination and control system and method thereof

An attitude determination and control method for determining an attitude of a satellite, including:

• a propagate stage including:
• obtaining a first propagation result at time t, by using a processor having a Quaternion Kalman Filter (QKF), to perform a calculation according to at least one of a torque-input command from a controller and a measured output torque on an attitude actuator, wherein the attitude actuator comprises at least one indirect attitude actuator, and wherein the at least one indirect attitude actuator includes a spherical motor;
• and
• an update stage including:
• using 1st to Nth environmental sensors to simultaneously measure 1st to Mth targets at time t to obtain 1st to Nth measured values, wherein both N and M are integers greater than or equal to 2, and M is a positive integer less than or equal to N;
• obtaining a second propagation result by using the processor to perform a calculation according to the 1st to the Nth measured values measured at time t, and then to update the first propagation result;
• and
• repeating the steps of obtaining the first propagation result, updating the first propagation result, and obtaining the second propagation result at time t+1, wherein the steps of obtaining the first propagation result and the second propagation result and updating the first propagation result are repeated no more than N times, wherein the processor is configured to detect and remove the measurement values of sensors that are not functioning properly so that the number of updating the first propagation result and obtaining the second propagation result is reduced to less than N times.

An attitude determination and control method for controlling an attitude of a satellite, including:

• a propagate stage including:
• receiving an attitude command from a user;
• and
• obtaining a first propagation result at time t, by using a processor having a Quaternion Kalman Filter (QKF), to perform a calculation according to at least one of torque-input command from a controller and an measured output torque of an attitude actuator measured by a torque sensor, wherein the attitude actuator includes at least one indirect attitude actuator, and wherein the at least one indirect attitude actuator includes a spherical motor;
• an update stage including:
• using 1st to Nth environmental sensors to simultaneously measure 1st to Mth targets at time t and to obtain 1st to Nth measured values, wherein both N and M are integers greater than or equal to 2, and M is a positive integer less than or equal to N;
• obtaining a second propagation result by using the processor to perform a calculation according to the 1st to the Nth measured values measured at time t, and then to update the first propagation result;
• and
• repeating the steps of obtaining the first propagation result, updating the first propagation result, and obtaining the second propagation result at time t+1, wherein the steps of obtaining the first propagation result and the second propagation result and updating the first propagation result are repeated no more than N times, wherein the processor is configured to detect and remove the measurement values of sensors that are not functioning properly so that the number of updating the first propagation result and obtaining the second propagation result is reduced to less than N times;
• and a control stage, including:
• obtaining a torque-control command by using the processor to perform a calculation for compensation purposes according to the attitude command and the second propagation result;
• and
• altering the satellite's attitude using the attitude actuator to output a torque to the satellite according to the torque-control command.