Hand-Guidance of a Mobile Manipulator Using Online Effective Mass Optimization

This work addresses the field of human-robot collaboration, in particular, the hand-guidance of a redundant mobile manipulator. An efficient hand-guidance is related to the improvement of the inertial properties of the end-effector felt by the operator, as these describe the effort to guide the robot. In this regard, the operational space formulation is used to minimize the effective mass in the null space of the hand-guidance task. The minimization is based on a geometric ellipsoid representation and applies a gradient descent method. The approach is tested on the KUKA VALERI mobile manipulator and implemented on a real-time framework, whereby a particular focus is on stability and safety. For this purpose, a power limitation is proposed. Finally, the improvement of the effective mass related to a specific direction is discussed.