Spacecraft attitude determination using electrostatically suspended gyroscope with rotating rings

This article presents a novel method for satellite attitude determination, using two electrostatically suspended gyroscopes (ESGs). In this method, two superconducting rings (like gimbals) rotated around each suspended spherical rotor, which causes a variable flux in the rings. A voltage will be induced in the rings according to Faraday's law of induction. Satellite attitude is determined by integrating of the induced voltages and strap-down rate gyros using the extended Kalman filter. This gyroscope works precisely when the rotor is maintained at the center of the gyroscope cavity, between three pairs of the circular electrodes, and then a backstepping control algorithm is designed for this purpose. The performance of attitude determination using such sensor and designed control algorithm is evaluated by six-degree-of-freedom simulation of a satellite in the MATLAB software. The simulations show the proposed algorithm works in an excellent manner and has lower than a few hundred arc second errors. The accurately aligning of rotors in the known direction to space is essential and is another problem that we do not address here.