A normal form augmentation approach to adaptive control of space robot systems

A free-floating space robot system is modeled as an extended robot which is composed of a pseudo-arm representing the base motion resulting from six hyperthetic passive joints and a real robot arm. The model allows categorization of the space robot as an under-actuated system, and reveals fundamental properties of the system. Through input-output linearization of the model, a nontrivial internal dynamics is demonstrated, and an adaptive control scheme based on a formal form augmentation approach is proposed. This approach overcomes two fundamental difficulties in adaptive control design of space robot systems, i.e., nonlinear parameterization of the dynamic equation and uncertainty of kinematic mapping from Cartesian space to joint space