In this paper, a prosthetic robot hand was designed and fabricated and experimental evaluation of the realization of basic gripping motions was performed. As a first step, a robot finger was designed with same structural configuration of the human hand and the movement of the finger was evaluated via kinematic analysis. Electromyogram (EMG) signals for hand motions were measured using commercial wearable EMG sensors and classification of hand motions was achieved by applying the artificial neural network (ANN) algorithm. After training and testing for three kinds of gripping motions via ANN, it was observed that high classification accuracy can be obtained. A prototype of the proposed robot hand is manufactured through 3D printing and servomotors are included for position control of fingers. It was demonstrated that effective realization of gripping motions of the proposed prosthetic robot hand can be achieved by using EMG measurement and machine learning-based classification under a real-time environment.

This paper presents a robot hand inspired from grasp and grip mechanism of human hand. In human hand, grasp and grip are different terms: Human hand can grasp an object adaptively by individual pulling of each finger’s tendon. Once the fingers make contact with the object, the human hand can grip the object with a larger force by simultaneous pulling of the tendon of each finger. Inspired from this, we propose a mechanism decoupling flexion drive and force-magnification drive for a wire-driven robot hand. The flexion drive consists of electric motors pulling the wire of each finger to make adaptive movement of the robot hand (grasp). The force-magnification drive consist of a hydraulic cylinder that pulls the wire of each finger simultaneously (grip). We also propose adaptive grasp mechanism using spring linkage. It is possible to grasp the irregular objects of limited size without a complex control algorithm or sensor system. We experimentally verified that the grip force of the prototype robot hand exceeds 300N which is 10 times larger than the electric motor alone.