Adaptive Synergetic Optimal Control for Attitude Tracking of Rigid Spacecraft

The problem of adaptive optimal attitude tracking control for a rigid spacecraft is addressed in the presence of inertia uncertainty and external disturbances. Synergetic control technique is adopted to derive tracking controller first which is dependent on inertia matrix. The controller is then redesigned to be adaptive by estimation of inertia parameters. The Modified Rodrigues Parameter (MRP) is used along with its associated shadow set as the kinematic variables since it forms a nonsingular set for all possible rotations. Some salient features of the proposed controllers are that they have optimality property with respect to a meaningful cost functional and they can potentially eliminate or reduce attitude errors in the presence of constant external disturbances. Simulation results demonstrate the efficiency of the proposed synergetic optimal control strategy in achieving attitude tracking.