An active coupling mechanism with three modes of operation for modular mobile robotics

This paper presents a new design for a docking interface that enables rigid, reversible and non-back-drivable coupling between robotic modules in a chain architecture. The distinctive merit of the proposed interface is exhibited in its ability to operate in three independent modes. In the drive mode, the motor torque is directed to drive the host module. In the neutral mode, the motor torque aligns the coupling elements prior to docking. In the clamp mode, the motor torque actuates the revolute joint resulting from this docking process, thus allowing one module to revolve relative to its neighbors in the formation. In this paper, an optimality analysis of the unique kinematic properties of the dual-rod slider-rocker (DRSR) mechanism which enables this tri-state operation is presented. This analysis is supplemented by simulations and experimental results that validate these optimal kinematics, as well as the rigidity and the three operation modes of the docking interface.