Design and Verification of a Gravity-Compensated Tool Handler for Supporting an Automatic Hair-Implanting Device

Gravity-compensated arms are widely used to support mechanical hand-held devices such as laser therapy machines and screw tapping machines. Particularly for heavy devices that require repetitive motion, it is necessary to apply correct gravity-compensation mechanisms and also minimize friction to move them lightly. Therefore, we developed a statically balanced passive tool handler that allows users to handle a heavy automatic hand-held hair-implanting device with minimal effort. To allow the balancing of all the movements of six degrees of freedom, this balancing arm adopted a spherical gimbal for orientating at the end of a positioning part utilizing noncircular pulleys, while providing multiple strands of electric wires for controlling the attached distal device. The proposed design is quantitatively evaluated by measuring the required joints torque for movement using a practical prototype. Experimental results show that the tool handler has an excellent balancing ability, and it is expected to be applied to support various heavy devices in the future.