Adaptive control of free-floating space robot with inertia parameter uncertainties

In order to cope with the inertia parameter uncertainty of a free-floating space robot system, an adaptive trajectory tracking control method is proposed in Cartesian space. Dynamic equations in the joint space of the free-floating space robot system are formulated using the extended manipulator model, and then the dynamic equations in Cartesian space of the free-floating space robot system are derived. During the design of the adaptive controller for the free-floating space robot based on inverse dynamics, a nominal controller with fixed parameters offline and a compensative controller online are proposed to ensure invertibility of the inertial matrix of the dynamics model and real-time estimation of the parameters. The closed-loop system is proved to be stable and convergent by Lyapunov methods. Finally, numerical simulations of a two-link planar free-floating space robot are given using the proposed control method, which demonstrate good trajectory tracking performance of the end-effector of the free-floating space robot in Cartesian space.