Design of a Rectangular-type Finger Rehabilitation Robot

Gab-Soon Kim

, Hyeon-Min Kim

Young-Guk Kim

, Hee-Suk Shin

and Jungwon Yoon

Department of Control and Instrumentation Engineering, ERI, Gyeongsang National University, Jinju, Republic of Korea

Department of Rehabilitation Medicine, School of Medicine, Gyeongsang National University, Jinju, Republic of Korea

School of Mechanical Engineering, Gyeongsang National University, Jinju, Republic of Korea

Keywords: Finger Rehabilitation, Rehabilitation Robot, Force Sensor, Intelligent Robot.

Abstract: This paper describes the development of a finger-rehabilitation robot for rehabilitating stroke patients'

fingers and other patient’s paralyzed fingers. The developed finger rehabilitation robot is composed of a

thumb-rehabilitation robot instrument and four finger rehabilitation robot instruments. The finger-

rehabilitation robot could exercise fingers of patient for their rehabilitation. A control characteristic test of

the developed rectangular-type finger-rehabilitation robot was carried out, and the results confirmed that the

robot could be used for the flexibility rehabilitation exercise for the fingers of normal person and patients.

1 INTRODUCTION

A stroke patient’s fingers and other patient’s

paralyzed fingers usually have reduced functions

unlike a normal person, because they usually have

varying weakness of force. Therefore, their fingers

undergo a rehabilitation exercise to rehabilitate their

initialization functions. The finger-rehabilitation

robot can spread out five fingers and turn them

inward perfectly. The robot must perform force

control procedures for the patients’ safety in the

finger-rehabilitation exercise, because the fingers of

patients have different spreading extents.

Brokaw developed a finger rehabilitation system

using a spring force which assists a stroke patient in

grasping an object. Ren developed a system which

could spread out and turn inward a patient’s thumb,

and a system which could spread out and turn

inward his/her four fingers. The weakness of that

system was that it could not exercise each finger

individually. Connelly developed the air pressure

gloves system which can blow and deflate air into a

patient’s gloved hand to spread the hand out and turn

the gloved fingers’ inward. The weaknesses of these

developed systems in the paper are that they cannot

exercise the spreading out patient’s fingers perfectly,

and they also can't safely be used in the exercise for

the rehabilitating of patients fingers because they

don’t have a force sensor and therefore don’t have

any force controls.

In this paper, the rectangular-type finger-

rehabilitation robot which can perform a flexibility

rehabilitation exercise was developed for fingers’

rehabilitation exercises. The links of five finger-

rehabilitation robot instruments were designed using

the software Matlab, after which the body of finger-

rehabilitation robot was designed and manufactured,

and then a control characteristic test of the

developed rectangular-type finger-rehabilitation

robot was carried out.

2 DESIGN AND MANUFACTURE

OF ROBOT

2.1 Design of the Links’ Lengths of the

Finger-rehabilitation Robot

In order to design the finger-rehabilitation robot

instruments, the lengths of a hand and each finger is

measured. After which, the movements that spread

out fingers and turn the fingers inward are simulated

with their data collected to get the links’ lengths.

The average length of a hand, each finger and each

knuckle were measured from ten university students,

and they are as follows; the length of thumb is

68mm, that of forefinger is 101 mm, that of middle

finger 114 mm, that of ring finger 105 mm, that of

little finger 87 mm. The spreading angle of each

finger is about 85. The values are to design each

finger-rehabilitation robot instrument in the

simulation.

443

Kim G., Kim H., Kim Y., Shin H. and Yoon J..

Design of a Rectangular-type Finger Rehabilitation Robot.

DOI: 10.5220/0004033204430446

In Proceedings of the 9th International Conference on Informatics in Control, Automation and Robotics (ICINCO-2012), pages 443-446

ISBN: 978-989-8565-22-8

 2012 SCITEPRESS (Science and Technology Publications, Lda.)

Figure 1: Schematic diagram of links for the finger-

rehabilitation robot instrument.

Figure 1 shows schematic diagram of the links of

finger-rehabilitation robot instrument for the

simulation, and these are composed of link 1~6 with

each length of l1, l2, l3, l4, l5 and l6, the angle

between the length direction Link 1 and horizontal

axis is θ

, the angle between Link 1 and Link 2 is θ

the angle between Link 2 and Link 3 is θ

. The

structure of the finger-rehabilitation robot instrument

is as follows; each finger’s end knuckle is fixed to

the end of Link 6, Link 3 and Link 4 are composed

of a body, Link 2, Link 5 and Link 6 are jointed to

Link 3 and Link 4, and Link 1 and Link2 move in a

horizontal direction and vertical direction

respectively. In the simulation, the horizontal length

of Link 1, the vertical length of Link 2 and the angle

(θ

) between Link 2 and Link 3 are made in

accordance to the movement of the jointed point (x,

y), and they then spread out the fingers and turn

them inwards. The horizontal length of Link 3 and

the vertical length of Link 4 are derived through a

simulation using the software MATLAB. In order to

create the simulation, equations of forward

kinematics and inverse kinematics must be derived.

If x and y are variables, the equations of forward

kinematics could be derived. The equation for

calculating x can be written as follow.

3431

sin)(



lllx 

(1)

The equation for calculating y can be written as

follow.

3432

cos)(



llly 

(2)

If the lengths of Link 3, Link 4 and Link 5 (l3,

l4, l5) and x, y are considered constant,

)/)(cos

3263

lll 



, is the equation of reverse

kinematics, the variables l1, l2, θ

can be determined

as follows.

6343

))((

lylll





(3)

)(cos

ll 







(4)

3431

sin)(



llxl 

(5)

(a) Thumb

(b) Forefinger

(d) Ring finger

(e) Little finger

Figure 2: Graph of the simulation results for the finger-

rehabilitation robot instruments.

The simulation of each finger is carried out from

the turned inward finger to the spread out of said

finger. The lengths of Link 6 and Link3+Link4 for

the thumb are 46mm and 90mm respectively, and

those for middle finger are 76mm and 225mm

respectively. The lengths of forefinger, ring finger

and little finger are determined by the equal size of

those of middle finger, because the length of middle

finger is the greatest. The (a), (b), (c), (d) and (e) of

Figure 2 which are depicted graphic form show the

results of the simulation using the finger-

rehabilitation instruments from the turned inward

fingers to spread out fingers. When the thumb is

ICINCO 2012 - 9th International Conference on Informatics in Control, Automation and Robotics

444

divided into six sections from the turned inward

finger (0°) to spread out finger (84°) with an interval

of 14°, the horizontal moving distance (x) of Link 1

is 114.4mm, the vertical moving distance (y) of Link

2 is 43.4mm, and the rotational angle between Link

2 and Link 3 is 60.1°. When the four fingers

(forefinger, middle finger, ring finger and little

finger) are divided into seventeen sections from the

turned inward finger (0°) to the spread out finger

(85°) with the interval of 5°, the horizontal moving

distance (x) of Link 1 for each finger is 192.2mm,

214.0mm, 195.4mm and 167.0mm, the vertical

moving distance (y) of Link 2 for each finger is

43.4mm, 54.8mm, 51.1mm and 45.4mm, and the

rotational angle between Link 2 and Link 3 for each

finger is 60.1°, 86.5°, 80.1° and 69.2°, respectively.

As a result of the simulation, the length of Link 6

and Link 3+Link 4 of thumb-rehabilitation robot

instrument is 46mm and 90mm respectively, and

those of four finger-rehabilitation robot instrument

are 76mm and 225mm.

Figure 3: Photograph of the manufactured finger-

rehabilitation robot.

2.2 The Design and Manufacturing of

the Finger-rehabilitation Robot

The Figure 3 shows the photograph of the

manufactured finger-rehabilitation robot. The robot

is composed of a thumb and four finger-

rehabilitation robot instruments They are composed

of a hand support (body), a left and right moving

instrument for the thumb-rehabilitation robot

instrument, four up and down moving instruments

for the four finger-rehabilitation robot instruments,

five front and rear moving instruments for the thumb

and four finger-rehabilitation robot instruments, a

force measurement and transmitting instrument for

the thumb-rehabilitation robot instrument and four

force measurement and transmitting instruments for

the four finger-rehabilitation robot instruments.

The hand support (body) is used to fix patient’s

left hand, and is attached to the front and rear

moving instrument, and its dimensions are 220mm

in width, 451mm in length and 94mm in height.

Each instrument is composed of a LM guide

(RSR9KM), a ball screw (MTF1202-3.7), a motor

and gear (349380, 29:1) and a support, and they

vertically move the force measurement and

transmitting instrument up to 60mm, respectively.

The front and rear moving instrument of each finger-

rehabilitation robot instrument is fixed to the body

and the applied force to each finger is done by

moving each finger with the up and down moving

instrument in conjunction with each support of force

transmitting instrument. Each fixing block of the

each up and down moving instrument are attached to

a single LM guide rail with each of the front and rear

moving instruments. The horizontally movement of

the force measurement and transmitting instrument

is up to 300mm.

Each force measurement and transmitting

instrument of each finger-rehabilitation robot

instrument is composed of a finger fixing link, a

finger exercising link, a support and an upper and

lower moving block. The four two-axis force sensors

which measures Fx force and Fy force are

manufactured for four finger-rehabilitation robot

instruments, and they are fixed to each finger

exercising link, and they each have the capacity of

100N. The sensors measure the pulling and pushing

forces of fingers. Each force measurement and

transmitting instrument is connected to the center of

each fixing support and the end of each up and down

moving instrument, respectively.

2.3 Control Characteristic Test of

Finger-rehabilitation Robot

The flexibility rehabilitation exercise is performed

for improving the flexibility of the hardened five

fingers, and it is during these exercises which the

fingers are spread out and turn inward according to

the drawing trace of the last knuckle. Figure 4 shows

the photographs of the characteristic test for

flexibility rehabilitation exercise using finger-

rehabilitation robot instrument.

Figure 5 shows the graphs of the flexibility

rehabilitation exercises using the finger-

rehabilitation robot. The graphs showed in the cases

of the spreading out of the thumb, forefinger, middle

finger and ring finger, that the forces were between

the range of 0~22s and each had a maximum force

Design of a Rectangular-type Finger Rehabilitation Robot

445

Figure 4: Photographs of characteristic test for finger-

rehabilitation robot instrument.

(a) Thumb

(b) Forefinger

(d) Ring finger

(e) Little finger

Figure 5: Graphs of flexibility rehabilitation exercises.

of about 18N, 13Nm 14N and 13N with reaches of

about 22s. In cases where the fingers were turned

inward the measured forces were decreased by about

22s respectively. In case of the spreading out of the

little finger the graph showed, the forces were

between the ranges of 0~17s with a maximum force

of about 10N with reaches of about 17s. In case of

the little finger being turned inward, the measured

force was decreased by about 17s. The graphs

showed that the progressions of the tests of thumb,

forefinger, middle finger and ring finger, and little

finger were finished within 45s, and 34s

respectively, because the robot could stop after

spreading out the fingers perfectly and would then

return to the starting position. Thus, the finger-

rehabilitation robot instruments could be used for the

finger-flexibility rehabilitation exercises of

rehabilitating patients’ fingers.

3 CONCLUSIONS

The purpose of this paper is to showcase the

rectangular-type finger rehabilitation robot which

can perform both the flexibility rehabilitation

exercise. The operating characteristic test of each

fingers’ rehabilitation robot instrument was carried

out using five fingers of normal person, and the

characteristic tests were safely operated in the

flexibility rehabilitation exercise.

ACKNOWLEDGEMENTS

This research was supported by Basic Science

Research Program through the National Research

Foundation of Korea (NRF) funded by the Ministry

of Education, Science and technology (2010-

0087281)

REFERENCES

Brokaw, E. B., Holley, R. J., Lum, P.S., 2010. Hand

Spring Operated Movement Enhancer (HandSOME)

Device for Hand Rehabilitation after Stroke.

Engineering in Medicine and Biology Society

(EMBC), 2010 Annual International Conference of the

IEEE. pp. 5867-5870.

Ren, Y., Park, H. S., Zhang, L. Q., 2009. Developing a

whole-arm exoskeleton robot with hand opening and

closing mechanism for upper limb stroke rehabilitation.

Rehabilitation Robotics, 2009. ICORR 2009. IEEE

International Conference on. pp. 761-765.

Connelly, L., Jia, Y., Toro, M. L., Stoykov, M. E., Kenyon,

R. V., Kamper, D. G., 2010. A Pneumatic Glove and

Immersive Virtual Reality Environment for Hand

Rehabilitative Training After Stroke. Neural Systems

and Rehabilitation Engineering, IEEE Transactions

on. vol. 18, no. 5, pp. 551-559.

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