An Electrostatically Actuated Gecko Adhesive Clutch

This work presents a new variation on electrostatic clutches that uses gecko-inspired adhesives instead of friction for its braking force. As a result, it requires no power or normal pressure to remain engaged or disengaged. It requires only a brief pulse of voltage to switch states. In some applications, this capability is desirable for safety reasons. As an illustration, the clutch is incorporated into the needle-driving axis of a magnetic resonance compatible teleoperated robotic system. Adding the clutch has no effect on imaging quality and provides a fail-safe brake to prevent the needle axis from dropping in the event of a power failure. As a second application, the clutch is integrated into a force-controlled robotic gripper where it allows the motor to be turned off while maintaining a static grasping force. In both applications, the 20 ms response time of the clutch prototypes is advantageous to prevent any motion immediately after receiving a braking command. This work additionally presents details on the design and manufacturing process of the gecko-inspired clutch, including a new, non-uniform profile for the microscopic adhesive features. The fabricated prototypes are thin (305 mu m per layer) and flexible. They provide a controllable, adhesive braking force of 60 kPa per layer. Multiple layers can be assembled to increase the braking force.