Evaluation of the Force-Current Relationship in a 3-Finger Underactuated Gripper

This paper provides a detailed analytic evaluation of the force-current relationship for a real underactuated gripper, whose geometry presents some differences with respect to the cases usually considered in the literature. Differently from other approaches, the model proposed can work in two ways: calculating the current needed to exert a given force, and calculating the force applied by the gripper when a known current is impressed to the motor. Calculating the current as a function of the forces is not a trivial task; however, this is possible in the proposed solution thanks to the use of a single input parameter describing the set of forces applied by the gripper. The proposed approach was tested in real experiments, demonstrating that the proposed model is capable of providing a very good estimation in several working conditions.