Coordinated Control of Space Robots with Base Attitude Represented by Rotation Matrices in SO(3)

This paper addresses the coordinated control of free-flying/floating space robots (FFSRs) to simultaneously control the base attitude and the manipulator for in-orbit tasks. Utilizing rotation matrices in the special orthogonal group SO(3) to provide a global and unique representation of the base attitude without singularity or ambiguity, a new model for FFSRs is developed. The paper proposes a global base attitude and computed torque control (GBA-CTC) law to enable coordinated control of FFSRs. Numerical simulations of the proposed model and controller for FFSRs are performed while maintaining the geometric properties of SO(3). Simulation results show high control accuracy in the task to smoothly approach and synchronize with a non-cooperative rotating object in the presence of bounded disturbances.