Design, principles, and testing of a latching modular robot connector

Connection and disconnection occur often in modular robotics. Furthermore, position errors increase in chain-style modular robots as chains get longer. This paper presents a passive (unactuated) compliant two-layer latching mechanism compatible with planar docking mechanisms such as the X-Face, with design considerations and important design parameters empirically identified. Design parameters such as alignment, face curvature and overhang width are shown to have unintuitive effects on the behavior and strength of the connectors. The latch mechanism has a bonding ratio (force of the bond over force required to engage bond) in the range of 20 to 76, depending on the design parameters used. The paper also presents a reconfiguration control sequence that combines the module actuation forces with the connectors´ natural forces to increase the reliability of the connection process and reduce the maximum force required. In addition, several types of reconfiguration are performed, including reconfiguration with a 12 module long chain that demonstrates the connectors´ robustness to error.