  In this paper, we propose a unified whole-body control framework for
velocity-controlled mobile collaborative robots which can distribute task
motion into the arm and mobile base according to specific task requirements by
adjusting weighting factors. Our framework focuses on addressing two
challenging issues in whole-body coordination: 1) different dynamic
characteristics of the mobile base and the arm; 2) avoidance of violating both
safety and configuration constraints. In addition, our controller involves
Coupling Dynamic Movement Primitives to enable the essential capabilities for
collaboration and interaction applications, such as obstacle avoidance, human
teaching, and compliance control. Based on these, we design an adaptive motion
mode for intuitive physical human-robot interaction through adjusting the
weighting factors. The proposed controller is in closed-form and thus quite
computationally efficient. Several typical experiments carried out on a real
mobile collaborative robot validate the effectiveness of the proposed
controller.
