Coordinated motion control of a dual-arm space robot for assembling modular parts

Abstract

This paper aims to develop a coordinated control strategy for assembling two modular parts carried by a free-floating dual-arm space robot. The assembly task is divided into pre-assembly and final assembly phases. During the pre-assembly phase, in order to drive the modular parts to desired relative positions and attitudes, the coordinated motion between two arms are planned by formulating a special optimization objective function based on the generalized relative Jacobian matrix (GRJM). Notably, the coordinated motion control law is formulated in terms of relative position and pose errors whereby more degrees of freedom of manipulators are released for disturbance minimization and collision avoidance. In the final assembly phase, trajectory tracking problem of one arm is addressed while the other arm is kept rest. More specially, the translational velocity of the moving arm is involved in the objective function and its angular velocity in the constraint equations, which ensures the attitude coordination between two modular parts during position tracking. Finally, the proposed control strategy is demonstrated through numerical simulations and experiment tests using an air bearing simulator floating on a granite testbed.