Control bandwidth recovery of flexible pointing systems

Instrument pointing control systems mounted on spacecraft are inherently bandwidth-limited (due to lightly-damped flexible modes of the spacecraft) compared to the same system mounted to a rigid body (such as the ground). This work is concerned with the recovery of control bandwidth for space-based pointing systems via the application of μ-tip control, a passivity-based control methodology. First, the equations of motion of a pointing system are derived. Then, using a “massive payload assumption” a passive input-output map is established between a modified output, called the μ-tip rate, and a modified control input. Bandwidth recovery is confirmed by investigating the frequency response of the linearized system. Simulation results that demonstrate the performance of the developed control algorithm are presented.