Parallel Four-Bar Linkage with Geared Rolling Joints for Reliable Robot Wiring

Conventional methods for providing electrical wiring from the base joint to the distal joint and the end effector include a dress pack, a hollow joint, and a slip ring. However, finding one that enables predictable wiring shape and easy maintenance is challenging. In this paper, the use of geared rolling joints is proposed to provide stable electrical wiring to the end of the robot, and their mechanical characteristics are analyzed. Furthermore, a cable-driven prototype of a parallel four-bar linkage comprising the unit rolling joints with gears is manufactured to confirm that the wiring path and driving torque exhibit predictable repeatability even when the electrical wires are installed. Moreover, the proposed joint structure may have additional advantages of easy addition and modification of the wiring. Therefore, the proposed rolling joint structure should provide a new option for designing robot joints.