Design of Multi-Grip Patterns Prosthetic Hand With Single Actuator.

In hand prosthesis design, the important characteristics that directly affect hand performance are the ability to grasp various type of objects, grasping force that provides stability for holding objects, and cosmetic appearance that resembles the human hand. The presence of all of these characteristics is currently a challenging task for prosthesis design. This paper presents the design of a five-fingered prosthetic hand that has multiple grip patterns with the use of only one actuator in order to perform important tasks in daily life and which achieves significant grip force from the large size of the actuator. The prosthetic hand is capable of performing one neutral position and two grip patterns that are dominant in daily life tasks. Different move patterns are achieved through the use of multiple sets of rigid four-bar linkages which provide different motions to fingers and thumb when the mechanism is actuated to the opposite direction. This paper describes the design of the prosthesis, mechanism synthesis, and achieved performance. The prosthetic hand developed here, having one degree of freedom, is an improvement from conventional single-actuator hands, which can only perform open/close motion. Whereas achieved grip force (34.5 N) is higher than multiple-actuator hands in market. Thus, this design could be an alternative answer of improvement between conventional and multiple degree of freedom prosthetic hands.