Nonholonomic dynamic rolling control of reconfigurable 5R closed kinematic chain robot with passive joints

Abstract

We have developed a self-reconfigurable robot which can form a 5R closed kinematic chain, only two of whose joints are actuated. This paper discusses its dynamic rolling. When it rolls, it has one DOF of its absolute orientation besides two DOFs of its shape. We show that the absolute orientation is subject to an acceleration constraint, not a velocity constraint. Therefore, the dynamics of the rolling motion needs to be formulated to control it. This paper proposes a controller which can reduce its negative acceleration caused by gravity. The shape and orientation of the robot cannot be controlled simultaneously. This paper proposes a control strategy switching shape and orientation controllers. We verify the effectiveness of the control strategy by simulations and experiments.