Design and Control of a Nonlinearly Compliant Robotic Finger

摘要

This report describes an inexpensive, modular robot finger utilizing exponentially stiffening springs between the actuators and joints. Controlling the deflection of these springs is equivalent to controlling force, since the deflection is directly related to the applied force through the spring's force-deflection curve. Therefore, the use of compliance in the joints transforms the problem of force control into one of position control, thereby simplifying force control algorithms, improving performance and allowing the use of small, cheap, gear-reduced actuators. The exponential nature of the compliance allows a constant percentage resolution of forces that can be exerted and sensed. This constant percentage resolution leads to an extremely large dynamic range and excellent contact sensing ability. These traits are also present in humans, and have been identified as essential to the dexterity of human fingers. The fingers can be used in combination to form a hand capable of grasping and grasp gaits, or individually for palpation and perception.