SATELLITE ATTITUDE SLEW MANEUVERS USING INVERSE CONTROL

Inverse dynamics is investigated as an efficient means of generating l arge angle satellite attitude slew manoeuvres. The required slew manoe uvres are specified using high order polynomials which result in a smo oth control torque profile. Such smooth torque profiles are of importa nce in avoiding excitation of elastic modes of the satellite structure . In addition, the polynomial functions may be used to define a slew t rajectory between arbitrary initial and final states allowing track-to -track manoeuvres. To compensate for uncertainties in the satellite dy namics, the inverse control is extended to include feedback linearisat ion about the nominal reference trajectory. It is shown that for rest- to-rest slew manoeuvres the resulting composite control is robust to u ncertainties in the satellite inertia matrix and to actuator degradati on. In addition, it is shown that complex paths may be generated throu gh the use of high order polynomial functions which contain all the in formation required to enforce user defined constraints and boundary co nditions in a compact, computationally efficient form.