<h2>AAS 95-418</h2><h2>Indirect Adaptive Nonlinear Attitude Control and Momentum Management of Spacecraft Using Feedback Linearization</h2><h4>S. J. Paynter and R. H. Bishop, The University of Texas, Austin, TX</h4><h2> Abstract </h2>An adaptive controller is developed for attitude control and momentum management of spacecraft.  The control law is based on nonlinear feedback linearization, where a coordinate transformation is introduced which takes the nonlinear system to normal form.  Once in normal form, a control is chosen to cancel the nonlinear dynamics, so that the new system behaves linearly.  Then, an extended Kalman filter based parameter identification scheme is added to estimate the inertia matrix.  The new estimate of the inertia matrix is then used to continue stabilizing the system.  Simulation results are given which show the controllers effectiveness in the presence of changing mass properties.<br><br>