rehabilitation

rehabilitation

Abstract—We have developed a novel robotic interface to train hand and finger function. HandCARE2 is a Cable-Actuated REhabilitation (CARE) system, in which each finger is free to move in space with a large range of movement, from a closed hand to full extension. The device, designed based on biomechanical measurements, can assist the subject in opening and closing movements of the hand and can be adapted to accommodate various hand shapes and finger sizes. The system uses a cable-spring transmission and a clutch system, which allow movement combinations of the five fingers with only two actuators. The device is safe, cost effective and offers multiple possibilities to train finger independence and coordination, with various grasps.

I.I NTRODUCTION

EHABILITATION robots are increasingly used across industrialized nations and may redefine physical therapy after stroke by motivating patients to train independently and at their convenience, promising an increase of therapy with existing human resources. However, very few devices have been proposed so far to train hand and finger function, despite the critical importance of the hand in performing activities of daily living [1].

II.C ONCEPT

HandCARE2 is a Cable Actuated REhabilitation system for the hand (Fig. 1A), where the motion of each finger can be assisted or resisted by a cable-spring mechanism, without spatially restraining the movement. The interface provides a large range of movement, from assisted finger extension to resisted grasp movement with the five fingers together. The interface is also able to train the right or left hand, and to adapt the position of the wrist for an improved comfort (Fig. 1C-D).

III.I MPLEMENTATION

The device is composed of two motors and five clutches to selectively combine the action of these motors. Five servomotors automatically switch the clutches between three modes: (i) actuation by the first motor, (ii) actuation by the second motor and (iii) blocked. Each clutch is linked to a cable that transmits actuation to the finger such that the fingertips are free to move in space, e.g. when one clutch is Manuscript received July 1, 2008. This work was supported by the National University of Singapore (R265-000-168-112) and Imperial College London.

L. Dovat, O. Lambercy and Teo C.L. are with the Department of Mechanical Engineering, National University of Singapore, R. Gassert and E. Burdet are with the Department of Bioengineering, Imperial College London, UK. Email: l.dovat@https://www.360docs.net/doc/1513957002.html,, e.burdet@https://www.360docs.net/doc/1513957002.html,. engaged with one of the motors, the corresponding cable is pulled and generates a force to extend the finger. As the motor pulls the cable in one direction, a bow spring applies a force in the opposite direction in order to maintain cable tension (push-pull system). The bow spring is also used to generate forces in the direction of finger flexion (Fig. 1B). The interaction between the subject and the robotic interface is measured by means of five encoders and five force sensors located at the output of the robot (at the subject’s fingertips).

The system also comprises five vibration motors that can be placed at different locations, e.g. on the fingertip or palm/back of the hand, to provide tactile feedback to stimulate the sensory system.

A CKNOWLEDGMENT

We thank therapists and stroke patients at stroke recovery clubs in Singapore and Vancouver who helped us determine the design of the HandCARE2.

R EFERENCES

[1]L. Dovat, O. Lambercy, R. Gassert, CL Teo and E Burdet, “Finger

function rehabilitation device,” US provisional patent US61/130/764, June 2008

HandCARE2: A Novel Cable Interface for Hand Rehabilitation Ludovic Dovat, Student Member, IEEE, Olivier Lambercy, Student Member, IEEE,

Roger Gassert, Member, IEEE,Etienne Burdet, Member, IEEE, and Teo Chee Leong

R

Fig. 1. HandCARE2 device for hand and finger rehabilitation (A) and

detail of the finger fixtures (B). The device can be oriented to provide

a comfortable position of the wrist (C-D).

978-1-4244-2701-7/08/$25.00 ?2008 IEEE64

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