Browsing by Subject "Prosthetic Hand"

Now showing 1 - 5 of 5

Open Access
A MYOELECTRICALLY CONTROLLED PROSTHETIC HAND FOR TRANSMETACARPAL AMPUTATIONS.
(2002) Weir, Richard F.; Grahn, Edward C.
We have developed a new externally-powered, myoelectrically controlled partial hand prosthesis that is suitable for fitting those persons with amputations at or more proximal to the level of the metacarpophalangeal (MCP) joint. This hand mechanism is capable of reasonable pinch forces (12 lbsf) and fast opening and closing (2 rads/sec). In a partial hand mechanism there is very little space available for the drive mechanism if an aesthetic result is to be achieved and any residual motion of the wrist is to be preserved. The challenge is to be able to fit all the requisite mechanisms and electronics in the highly confined volume that remains after accommodating the residual limb and still have reasonable performance.
Open Access
DESIGN OF A CLINICALLY VIABLE MULTIFUNCTIONAL PROSTHETIC HAND.
(2002) Weir, Richard F.
We are in the process developing a new multifunctional hand mechanism in the hopes of providing a new mechanism that will have superior function over today’s single degree-offreedom (DOF) mechanisms and yet be clinically viable. However, this is no easy task. There have been a multitude of multifunctional hands built, all of which have failed to find clinical application as an artificial hand replacement. During the 60s and 70s much time, effort, and money was invested in the development of externally-powered multi-functional hand-arm systems. Prime among these being the Edinburgh Arm [1], the Boston Arm [2,3], the Philadelphia Arm [4,5], the Belgrade hand [6,7], the Sven Hand [8], the Utah Arm [9]. However while many of today’s commercially available externally-powered elbow systems (Boston Elbow – Liberating Technology Inc [10], NYU Elbow – Hosmer-Dorrance, and Utah Elbow – Motion Control [11]) owe their origins to this era of upper-limb research no multifunctional hand mechanisms made the transition from the Laboratory into clinical practice.
Open Access
Development of a Clinically Viable Multifunctional Underactuated Hand Prosthesis Using Differential Transmissions
(2008) Clark, Stephen; Weir, Richard F.
We are now in the process of developing a multifunctional prosthetic hand that uses six commercially available DC electric motors and transmissions in an under-actuated system to drive 16 degrees of motion. Providing greater finger dexterity as well as a wide range of major prehension patterns may require many degrees of freedom. It has been shown that increasing the number of actuators to increase the degrees of freedom can result in a complicated system with many parts which can be heavy, unreliable and costly, and therefore clinically unviable. This paper presents a design that limits the number of motors needed in the device by utilizing differentials transmissions. By limiting the number of actuators and other mechanical components, complexity is reduced and reliability is increased while still achieving a high degree of motion. The function of the differential allows for adaptive grasping through the mechanical self-adaptability of the actuators. Each digit is independently driven by one motor and transmission with the power being distributed to each of the three joints by way of a differential transmission and kinematic linkages, with an additional degree of freedom added to the thumb for palmer rotation. We believe that this will produce a highly functional prosthetic device that will be able to achieve all major prehension patterns as well as having a degree of individual finger dexterity.
Open Access
Development of myoelectric controllers for hand prostheses
(2005) Kajitani, Isamu; Higuchi, Tetsuya
This paper describes a research project at the National Institute of Advanced Industrial Science and Technology (AIST) to develop a myoelectric controller. The myoelectric controller interprets control intentions from the operator by recognizing myoelectric signals. This kind of controller has typically been applied to control electric-powered prostheses. The most notable advantage of using the myoelectric controller is its capacity to utilize the residual muscular functions of physically-impaired persons. For example, in the case of a hand prosthesis, the myoelectric controller enables the amputee to utilize the residual functions of remnant muscles at their stump. Within the project, we initially designed a pattern classification LSI (Large Scale Integration) in 1998 [1], and as one central application of the LSI, we have subsequently been developing compact controllers for multi-functional prosthetic-hands. Employing this pattern classification LSI, the controller can adapt itself to the unique characteristics of a myoelectric signal distribution for a given individual user [1]. Moreover, in order to realize hand-prostheses that could become widely accepted, we started developing a basic functional hand prosthesis in 2002. This prosthesis has undergone some clinical evaluations, and the technology has already been transferred to a private company for commercialization. This paper outlines the development of the multi-function and basic function controller, as well as a basic functional mechanical hand.
Open Access
EVALUATION OF A PROTOTYPE ELECTRIC-POWERED PARTIAL-HAND PROSTHESIS
(2005) Heckathorne, Craig W.; Weir, Richard F.
A prototype partial hand mechanism has been developed for fittings at the trans-metacarpal level. Subjects selected for evaluation of the prototype device have absence of all fingers of the affected hand, all or some portion of the metacarpals present, at least one active intrinsic hand muscle, and relatively unimpaired wrist movement. The presence of one or two intrinsic hand muscles allows for proportional myoelectric control without resorting to forearm muscles that would be recruited during wrist positioning. The mechanism is suspended from the hand structure with a custom silicone socket. The socket extends no more proximal than the styloids so that the physiological wrist motion is unencumbered, allowing for orientation of the hand in a near physiological manner.