Abstract
Serial link robots with unactuated (passive) joints are attracting research interest. If two of such robots can couple with each other, they can reconfigure to a parallel robot, which can make the number of actuators equal to the number of degrees of freedom. If they can couple with each other at different portions of them, they can constitute a reconfigurable parallel robot. This paper proposes this concept of a robot, presenting that two two-link robots, the first joints of which are unactuated, can reconfigure to a 5-link planar parallel configuration and a 4-link planar parallel configuration plus one actuated link. This reconfigurable parallel robot has only two actuators but can have multiple functions by reconfigurations. Due to the unactuated joints, whether or not the two-link robots can couple with each other is a non-trivial problem. We propose coupling sequences for forming the 4-link and 5-link configurations and verify those experimentally.
