A Multigrasp Hand Prosthesis for Providing Precision and Conformal Grasps.

This paper presents the design of an anthropomorphic prosthetic hand that incorporates four motor units in a unique configuration to explicitly provide both precision and conformal grasp capability. The paper describes the design of the hand prosthesis, and additionally describes the design of an embedded control system located in the palm of the hand that enables self-contained control of hand movement. Following the design description, the paper provides experimental characterizations of hand performance, including digit force capability, bandwidth of digit movement, physical properties such as size and mass, and electrical power measurements during activities of daily living.

Functional assessment of the Vanderbilt Multigrasp myoelectric hand: a continuing case study.

This paper presents a case study involving the functional assessment of the Vanderbilt Multigrasp (VMG) hand prosthesis on a single transradial amputee subject. In particular, a transradial amputee subject performed the Southampton Hand Assessment Procedure (SHAP) using the hand prosthesis and multigrasp myoelectric controller in a series of experimental sessions occurring over a multi-week time span. The subject's index of function (IoF) improved with each session, although essentially plateaued after the fourth session, resulting in a IoF score of 87, which compares favorably to SHAP scores published in previous studies.

Assessment of a multigrasp myoelectric control approach for use by transhumeral amputees.

The authors have previously developed a multigrasp myoelectric controller, and assessed the ability of healthy subjects to control the configuration of a multigrasp hand prosthesis using musculature on the anterior and posterior aspects of the forearm, as would be representative of controller use by a transradial amputee population. In this paper, the authors conduct a similar study, this time to assess the capability of a transhumeral amputee to control a multigrasp hand from residual musculature on the upper arm. Specifically, experiments are conducted on five healthy subjects, comparing their ability to obtain one of seven hand postures in a virtual prosthesis from EMG measurement of the respective biceps and triceps musculature. The ability to control the virtual hand prosthesis is compared with their ability to do so with their intact hand, as measured by a dataglove. Results indicate an average transition time using the EMG controller on the biceps and triceps of 1.86 seconds, relative to 0.82 seconds with the dataglove.

Design of a hand prosthesis with precision and conformal grasp capability.

This paper presents the design of an anthropomorphic prosthetic hand that provides both precision and conformal grasp capability. Specifically, the design of the hand dedicates three actuators in a direct-drive manner to achieving precision grasp capability. The design additionally dedicates one actuator and six degrees of freedom, in addition to a compliant coupling, to providing a conformal grasping capability to the amputee. The design of the hand is described in this paper, and the various degrees of actuation are characterized with respect to grasp forces and finger speeds.

Preliminary functional assessment of a multigrasp myoelectric prosthesis.

The authors have previously described a multigrasp hand prosthesis prototype, and a two-site surface EMG based multigrasp control interface for its control. In this paper, the authors present a preliminary assessment of the efficacy of the prosthesis and multigrasp controller in performing tasks requiring interaction and manipulation. The authors use as a performance measure the Southampton Hand Assessment Procedure (SHAP), which entails manipulation of various objects designed to emulate activities of daily living, and provides a set of scores that indicate level of functionality in various types of hand function. In this preliminary assessment, a single non-amputee subject performed the SHAP while wearing the multigrasp prosthesis via an able-bodied adaptor. The results from this testing are presented, and compared to recently published SHAP results obtained with commercially available single-grasp and multigrasp prosthetic hands.

Multigrasp myoelectric control for a transradial prosthesis.

This paper presents the design and preliminary experimental verification of a multigrasp myoelectric controller. The controller enables the direct and proportional control of a multigrasp transradial prosthesis through a set of nine postures using two surface EMG electrodes. Five healthy subjects utilized the multigrasp controller to manipulate a virtual prosthesis to experimentally quantify the performance of the controller in terms of real time performance metrics. For comparison, the performance of the native hand was also characterized using a dataglove. The average overall transition times for the multigrasp myoelectric controller and the native hand with the dataglove were found to be 1.49 and 0.81 seconds, respectively. The transition rates for both were found to be the same (99.2%).

A multigrasp hand prosthesis for transradial amputees.

This paper presents the design of a multi-degree-of-freedom, anthropomorphic hand for transradial amputees, and also presents experimental data characterizing its performance. Unlike state-of-the-art commercially available prosthetic hands, the hand described herein is capable of providing eight canonical postures (and movement between these postures). The experimental characterization includes its capability to provide eight canonical grasp postures; the frequency response of finger motion; and its grasping force capability (as a function of finger position). Other performance specifications, such as total mass and audible noise, are also provided.