Constrained steering law of pyramid-type control moment gyros and ground tests

A constrained steering law of pyramid-type control moment gyros (CMGs) is presented, and its procedure and implementation are detailed. The steering law uses a constraining relation of four input variables of the CMG system and solves nonredundant kinematics. Though the angular momentum workspace of this method is much smaller than the original maximum workspace, singularity avoidance is ensured, and this steering law is much simpler than usual steering laws. This method also can be applied to steering four of the six units of a MIR-type CMG system, Advantages of the steering law are verified against a gradient method and a singularity-robust-inverse steering law by using a ground-test facility simulating spacecraft motion. Moreover, operational modes of the law and a mode-switching procedure are evaluated experimentally.