Electrostatic Clutch-Based Mechanical Multiplexer with Increased Force Capability

Abstract

As robotic systems become increasingly articulated, conventional actuation still dedicates one motor to each degree of freedom (DoF). Mechanical multiplexers address this limitation by allowing a single motor to control multiple outputs through clutches, reducing the number of required motors. However, previous multiplexers have relied on bulky mechanical clutch designs, limiting their development. This study presents an electrostatic capstan clutch-based transmission architecture that enables high-force mechanical multiplexing with independent, simultaneous, and fully actuated control of multiple outputs from a single motor. Our transmission implements four fully-actuated linear outputs, achieving individual output forces of up to 212 N and output speeds of up to 69.5 mm/s. We demonstrate our transmission on a commercial tendon-driven hand, where sequentially allocating system-wide torque capacity to individual outputs increased vertical grip strength by 4.09x and raised horizontal carrying capacity to 111.2 N, the highest reported among five-fingered tendon-driven robotic hands. These results demonstrate that electrostatic clutch-based mechanical multiplexing enables high-force, independent, simultaneous, and fully actuated control while overcoming the limitations of previous mechanical multiplexers.