Fuzzy control for a non-linear MIMO plant subject to control constraints

A rule based fuzzy controller is presented for attitude stabilization of a small satellite in low earth orbit. Active control Is done by using 3-axis magneto-torquing. A preferred torque vector can not always be generated from the magnetic coils in certain regions of the orbit, due to an unfavourable direction of the geomagnetic field vector. The main objective of an acceptable control algorithm will then be to optimize the control effort: minimize the desired influence on the controlled axis and minimize the undesired disturbances to the other axes. It was found that a fuzzy controller can achieve these goals in a computationally effective way, compared to other more involved MIMO algorithms, while performing just as well or better under similar conditions. This fuzzy controller solves the control constraint problem by choosing the best magneto-torquer, the polarity and switching instances