PD+ Based Output Feedback Attitude Control of Rigid Bodies

We address the problem of output feedback attitude control of a rigid body in quaternion coordinate space via a modified PD+ based tracking controller. Angular velocity is replaced by a low-gain dynamic extension. The controller ensures fast convergence to the desired operating point during transient maneuvers, while keeping the gains small. This contributes to diminishing the sensitivity to measurement noise hence, energy consumption may be expected to drop along with a decrease of the residual. More precisely, we show uniform practical asymptotic stability of the equilibrium point for the closed loop system in the presence of unknown, bounded input disturbances. Simulation results illustrate the performance improvement with respect to PD+ based output feedback control with static gains.