Base centroid virtual manipulator modeling and applications for multi-arm space robots

Due to the dynamic interaction, the motion of the arms alters the attitude and position of the base. To stabilize the centroid position of the base during on-orbital manipulation, we proposed the modeling concept of the "Base Centroid Virtual Manipulator (BCVM)" for free-floating multi-arm space robotic systems. Correspondingly, the trajectory planning method of the balance arm was addressed. The movement direction and the position of each joint of the BCVM are the same as those of the real space manipulator (SM). The end-effector\´s position of the BCVM denotes the equivalent centroid of the corresponding SM. By resolving the position-level kinematic equations, the singularity-free trajectory of the balance arm was then planned. Based on the BCVM model, the stabilization ability of a given balance arm can be easily determined by analyzing the workspace of the BCVM. Furthermore, the configuration and the mass properties of the balance arm can be optimized. Simulation results of joint trajectory tracking task verified the proposed model and method.