Design of a Highly Compliant Underactuated Prosthetic Hand This paper presents a highly compliant prosthetic hand based on a novel synergy mechanism. The prosthetic hand consists of a synergy mechanism, four fingers and one thumb. The synergy mechanism can transmit the power from two motors to four fingers. It can effectively reduce the number of motors. At the same time, it makes the prosthetic hand have excellent dexterity. The underactuated finger has three joints with two DOF. It has two main motion modes: coupled motion in free space and selfadaptive motion when contacting with the object, which can mimic the human finger as much as possible. The thumb uses one motor to drive the two flexionextension joints and uses a manual switch to drive the abductionadduction joint, which can reduce the number of motors and the cost efficiently. The performance evaluation is given to demonstrate the comprehensive performance in terms of the versatility, compliance, sensing, size, weight and cost of the proposed design.

A lowcost, compliant, underactuated prosthetic hand with custom flex sensors for finger bending estimation Access to quality prosthetics to aid in daily activities is a privilege of only 5 % of those in need of such equipment. It is noted that the high cost of these, associated with the lack of skilled labor, are two of the factors that aggravate the situation. Thus, the need for costeffective prosthetic technologies, targeting the population of developing countries, is observed. Inspired by this problem, this paper presents the process of conceptual study, design, and prototyping of a lowcost prosthetic hand that is compliant and underactuated. The hand has a wrist of two degrees of freedom, and five independently actuated fingers. One of the main contributions of this work is the design of a lowcost optoelectronic sensor for the fingeru0027s curvature estimation.