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.

No abstract

No abstract

No abstract

Nowadays, there are two socket fabrication methods in Thailand, which are resin casting and thermal vacuum method. The thermal vacuum forming method has more advantages than the resin casting method that ruins technicians' health from the volatile matter. Nevertheless, the thermal vacuum forming method can fabricate the socket with poor wall thickness distribution. The purpose of this paper is to study the effects of the feed rate of stump mould and the temperature distribution of the plastic sheet on the prosthetic socket wall thickness during the thermal vacuum forming process. The feed rates of stump mould were varied by using an industrial robot. The temperature distribution of the plastic sheet was controlled by circular and annular fiberglass insulators placed in its center. The results showed that the prosthetic socket wall thickness increases around the central area of the socket with a decreased feed rate of stump mould. The annular insulator increases the wall thickness slightly, while the circular insulator increases the thickness significantly. The wall thickness at the thinnest location increased from 1.6 mm up to 2.8 mm. In addition, wall thicknesses of areas beneath the circular insulator increased significantly between the marked positions-25 through +25.