Design of a Bilaterally Asymmetric Pedaling Machine and its Measuring

System for Medical Rehabilitation

Jinhua She

1,2,3

, Fajian Wu

, Hiroshi Hashimoto

, Toshihiro Mita

and Min Wu

2,3

Graduate School of Tokyo University of Technology, Hachioji, Tokyo 192-0982, Japan

School of Automation, China University of Geosciences, Wuhan, Hubei 430074, China

Hubei Key Laboratory of Advanced Control and Intelligent Automation for Complex Systems,

Wuhan, Hubei 430074, China

Master Program of Innovation for Design & Engineering, Advanced Institute of Industrial Technology,

Shinagawa-ku, Tokyo 140-0011, Japan

Keywords:

Bilateral Asymmetry, Lower Limb, Human Adaptation, Pedaling, Medical Rehabilitation.

Abstract:

Most commercially available rehabilitation machines are bilateral symmetric. This makes it difﬁcult to use

for people with lower-limb injuries. This paper explains the design of a bilaterally asymmetric pedaling

machine and its measuring system to solve this problem. Pedaling angles, strokes, and force of this machine

can easily be adjusted independently for the left and right legs. Pedaling force and strokes, heart rate, and

electromyogram (EMS) signals of walking muscles are recorded using a measuring system. This ensures

the interaction between lower-limb exercises, and the computer-based supervision and control of medical

rehabilitation. A prototype of a half model of the machine was built. Preliminary tests for the basic functions

were carried out and demonstrated the validity of the machine and the measuring system.

1 INTRODUCTION

The number of the elderly (people aged 65 or older)

in Japan was 34.63 million at October 1, 2016, which

was 27.3% in the percentage of population (Statistics

Bureau, 2016). Total spending of the nursing-care in-

surance system was 31.5trillion yen in ﬁnancial 2015,

which was as high as 32.7% of the annual expenditure

(Murayama, 2015). This caused a big burden for the

society. Statistics shows that more than one in three

Japanese will be the elderly and one in ﬁve will be 75

years old or older by 2025, and the number of peo-

ple in Japan needing rehabilitation will be keeping in-

creasing in the next decade. This has been called the

2025 problem (Ministry of Health, Labour and Wel-

fare, 2016). It has been becoming imperative for the

government to ﬁnd a way to solve the nursing-care

problem.

Walking is a basic action of daily life. Maintaining

or improving the physical strength of walking mus-

cles prevents the degradation of motor functions, and

promotes the mental and physical health of the el-

derly. This eventually beneﬁts the whole society.

Considering that pedaling is an effective exer-

cise for the walking muscles, we developed a new-

concept electric cart to integrate an exercise function

into the ability of old people to get around (She et al.,

2006). Unlike the commercially available carts, this

one mounted a pedal unit on the cart. It has two ped-

als and a pedal motor that generates a pedal load for a

driver. The speed of the pedal motor is determined by

the driver’s efforts, and constitutes a reference input

for the cart. The speed of the cart motor tracks that

reference. So, the experience is very similar to riding

a bicycle. To improve the effectiveness of pedaling as

a kind of exercise, we devised a mechanism that au-

tomatically selects a suitable load for the driver (She

et al., 2013). And many other pedaling-type rehabil-

itation machines, for example, (Anzai, 2014), have

also been developed. However, almost all of these

machines have the following problems:

1. the pedaling loads and strokes are bisymmetric;

and

2. the structure of the machines is ﬁxed.

So, they are not suitable for people with asymmetrical

ability for left and right limbs. As a result, people

have to adapt themselves to the machines, or in other

words, this kind of rehabilitation is machine centered.

This not only may cause a great pain in rehabilitation,

122

She J., Wu F., Hashimoto H., Mita T. and Wu M.

Design of a Bilaterally Asymmetric Pedaling Machine and its Measuring System for Medical Rehabilitation.

DOI: 10.5220/0006215101220127

In Proceedings of the 12th International Joint Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications (VISIGRAPP 2017), pages 122-127

ISBN: 978-989-758-229-5

Table 1: Statistics of average leg-extension force while seated (numbers in parentheses are standard deviations) (Sato, 1994).

One leg Right leg Left leg Subject

Man

2729 (506)

46 Jap. univ. students at Dept. Health

& Sport Sciences (18-24 y/o)

2067 (498) 1897 (478) Swedish

2887 (506) Dane

Woman

1260 (291) 1240 (303) Swedish

2133 (415) Dane

but also may degrade the will to rehabilitation.

Some studies have taken the bilateral asymmetry

into consideration. For example, the relationship be-

tween asymmetry and lower limb preference was ex-

amined (Carpes et al., 2010), and asymmetrical pedal-

ing patterns in Parkinson’s disease patients were mea-

sured in (Penko et al., 2014). However, they did not

consider the asymmetrical problem from the view-

point of the design of a rehabilitation machine.

To solve the problems, we developed a new kind

of a pedaling machine for rehabilitation (She et al.,

2016a; She et al., 2016b). Unlike other ones, it is hu-

man centered, that is, the structure of the machine is

variable, and is adaptable to different lower-limb re-

quirements. The pedaling loads and strokes can also

be adjusted independently. This ensures the durabil-

ity of rehabilitation and improve the efﬁciency of re-

habilitation. The combination of a bilaterally asym-

metric pedaling mechanism and a measuring system

makes it possible to carry out the interaction between

lower-limb exercises and the computer-based super-

vision and control of medical rehabilitation.

While the design of the mechanism of the pedal-

ing machine was explained in (She et al., 2016a; She

et al., 2016b), this paper explains the design of the

machine and the measuring system for pedaling, and

reports the results of some preliminary tests.

2 BASIC REQUIREMENTS FOR

PEDALING EXERCISE AND

MEASURING SYSTEM

The requirements for pedaling exercise are ﬁrst con-

sidered.

Rehabilitation is basically divided into three

stages: acute stage (1-14 days), recovery stage (up to

several months), and functional stage (several months

to years) (Dugan, 2006). This study focused on pro-

viding a means for the last stage, that is, for the func-

tional stage.

Since pedaling is an effective exercise to train the

walking muscles, we tried to build a new type of ped-

aling machine. There are two types of pedaling: ro-

tational and linear. Considering that a rotational ped-

aling motion is basically bisymmetric, it is not suit-

able for people with lower-limb injuries. On the other

hand, note that a linear pedaling motion can easily

be used to design an asymmetrical mechanism to suit

different requirements for left and right lower-limbs,

we used it for the development of the rehabilitation

machine in this study.

After ﬁxing the pedaling mechanism, we turn to

choose parameters for the pedaling. First, we select

a pedaling force. Note that the maximum of the av-

erage leg-extension force of one leg is about 2900 N

for young people (Table 1) (Sato, 1994). Since the leg

strength reaches its peak at 20s and then it decreases

with aging (Sato, 1994), and people who need reha-

bilitation have weak legs and are mainly in the middle

aged and elderly, it is enough to choose the maximum

force for pedaling to be

max

= 2000 N. (1)

Next, we select the parameters for pedaling stroke.

As pointed out in (Sato, 1994), ergonomicsshows that

there is an optimal pedaling region. It is given in Fig-

ure 1 for the deﬁnitions in Figure 2. For the optimal

region, the angle between the femur and the lower leg

is in the range [15

◦

, 90

◦

] when the knee is at the clos-

est position to the body, and [30

◦

, 90

◦

] when the knee

at the farthest position from the body. Considering

that a person needs rehabilitation may not sit and/or

pedal properly as a normal person does, and referring

to the results in (Timmer, 1991; Johnston, 2007), we

chose the angle between the femur and the lower leg

to be

θ ∈ [0

◦

, 90

◦

]. (2)

Equation (2) provides us a larger region than the opti-

mal one. This gives us a big freedom to suit different

kinds of requirements.

The stroke of a linear motion should also be cho-

sen to be long enough. It was chosen to be

L = 150 mm (3)

based on a preliminary test.

As for the design of the measuring system, the fol-

lowing points need to be considered:

Design of a Bilaterally Asymmetric Pedaling Machine and its Measuring System for Medical Rehabilitation

123

Max:

Seat reference

point

−40

−30

−20

−10

6040 80 100

Distance forward of

seat reference point [cm]

Distance below

seat reference point [cm]

Floor

(a)

(b)

Figure 1: Optimal pedaling region. (a) Top view and (b)

Side view (Upper case: heel. Lower case: toe) (Sato, 1994;

She et al., 2006).

• Measured data are suitably stored in a real-time

fashion.

• Measured data can easily be accessed.

• Measured data are displayed in a real-time fash-

ion, and it is easy to switch to the display of inter-

ested data.

• Data can be synchronized if needed.

3 DESIGN OF PEDALING

MECHANISM AND

MEASURING SYSTEM

A pedaling mechanism is designed in this section that

satisﬁes the requirements given in Section 2.

An oil damper, KINECHECK Super K (Meiyu

Airmatic Co. Ltd., Japan) (Table 2) was selected to

provide a pedaling load. It produces the largest damp-

ing force, and has the longest stroke in the class of

small dampers. While the maximum force is more

than the double of P

max

in (1), the stroke is only 70%

of L in (3). To ensure that the requirements (1)-(3) are

satisﬁed, a half model of a pulley-type pedaling mech-

anism was designed in Figure 3. It enlarges the stroke

Height of

knee

Hip-knee

distance

Seat reference

point

Height of

seat

Horizontal line

Near high point

Near low point

Far high point

Far low point

Seat reference

point

Figure 2: Deﬁnitions (Sato, 1994; She et al., 2006).

Table 2: Parameters of oil damper, KINECHECK Super K.

Model Overall length Stroke Force range

5001-31-4 356 mm 102 mm 23 ∼ 5440 N

doubly and reducing the load force to half. To ensure

(2), an adjusting part was designed and installed in the

machine. The inclined angle of the adjusting part can

be changed from 0

◦

to 90

◦

. A prototype of the pulley

mechanism for one leg was ﬁrst built for evaluation

(Figure 5).

As for the measuring system, we chose the heart

rate meter to be neo HR-40 (NISSEI Co. Ltd., Japan),

the force sensor to be LPR-C-1KNS15 and the dis-

placement sensor to be DTS-A-100 (Kyowa Elec-

tronic Instruments Co. Ltd., Japan), and the wireless

EMS sensor to be SX230-1000 and a 9-axes wireless

motion sensor (XYZ geomagnetism, XYZ accelera-

tion, and XYZ angular acceleration) (DKH, Japan).

And we constructed the measuring system as shown

in Figures 4 and 6.

The measuring system is used to supervise exer-

cises and to perform the interaction between the ex-

ercises and the computer-based control of rehabilita-

tion. It is important to select a suitable pedaling load

for a user based on the user’s physical condition. In

this study, a suitable load means a pedaling load that

does not seem heavy or light and can safely be used

for endurance training (U.S. Dept. of Health and Hu-

man Services, 2008). This human-computer interac-

tion not only maintains the motivation for rehabilita-

tion, but also results in enhanced exercise outcomes

in the long term.

HUCAPP 2017 - International Conference on Human Computer Interaction Theory and Applications

124

Adjusting part of

inclined angle

Stroke 192

Inclined angle: 20 deg

Oil damper

Displacement sensor

Stainless

wire

Adjusting part of

pedaling angle

Left lateral viewFrontal view

Figure 3: Pulley-type pedaling mechanism (half model).

Tread force sensor

(LPR-C-1KNS15)

Displacement sensor

(DTS-A-100)

Heart rate meter

(neo HR-40)

Compact recording system

(EDX-10A)

Wireless EMG sensor

(SX230-1000)

9-axes wireless

motion sensor

Wireless set

Transmitter (PH8310)

Amplifier (PH8320)

Data receiver (PH8020)

Data base

Interface

(Windows 8.1)

Display

Figure 4: Measuring system.

4 PRELIMINARY TESTS

Preliminary tests were carried out for the half model

and the measuring system for three subjects. The ped-

aling force was set in the range of 0-270 N (Level 0:

23 N; 3: 50 N; 6: 90 N; 9: 140 N; 12: 200 N; and 15:

270 N); and the angle of the inclined angle adjusting

part, 0-90

◦

. The sampling period of the measuring

system was set to be 0.02 s. Test results show that

the machine and the measuring system worked well

as designed. The sensors produced outputs correctly

for all the pedaling activities. It was found that pedal-

ing was carried out smoothly and comfortably for the

inclined angle in the range [40

◦

, 70

◦

]. Some typical

pedaling results are shown in Figure 7. As shown in

the ﬁgure, the pedaling period is the shortest and the

pedaling force is the largest for 60

◦

among the three

angles. This indicates that the inclined angle of 60

◦

the easiest one for pedaling.

Among the measured four EMG signals (quadri-

ceps femoris, biceps, soleus, and tibialis anterior),

that of quadriceps femoris is the largest, and that of

soleus is the smallest (Figure 8).

Design of a Bilaterally Asymmetric Pedaling Machine and its Measuring System for Medical Rehabilitation

125

EMG sensor

Transmitter

Force sensor

Displacement

sensor

Figure 5: A photo of experimental system.

Pedaling machine

Force

sensor

Displacement sensor

EMG sensor

Wireless module

Measuring screen

Figure 6: A photo of some components of measuring sys-

tem.

200

150

100

Dsplacement

(dotted) [mm]

6050403020100

Time [s]

160

120

Force (solid) [N]

160

120

Dsplacement

(dotted) [mm]

6050403020100

200

150

100

Force (solid) [N]

240

160

Dsplacement

(dotted) [mm]

6050403020100

120

Force (solid) [N]

(a)

(b)

(c)

Time [s]

Figure 7: Pedaling results for Load 9 (140 N) and inclined

angle of (a) 40

◦

, (b) 60

◦

, and (c) 80

◦

5 CONCLUSION

A new type of a bilaterally asymmetric rehabilitation

machine and its measuring system were designed in

-0.2

-0.1

0.0

0.1

0.2

Quadriceps femoris [mV]

6050403020100

-0.2

-0.1

0.0

0.1

0.2

Biceps femoris [mV]

6050403020100

-0.15

-0.10

-0.05

0.00

0.05

0.10

0.15

Soleus [mV]

6050403020100

-0.15

-0.10

-0.05

0.00

0.05

0.10

0.15

Tibialis anterior [mV]

6050403020100

Time [s]

Figure 8: EMG signals for Load 9 (140 N) and inclined

angle of 60

◦

this study. The machine is a linear pedaling type.

This ensures that a user can easily and independently

adjust the pedaling pose, pedaling displacement, etc.

in an asymmetrical fashion. Preliminary tests for the

basic functions have been tested, and the test results

demonstrated the feasibility of the machine.

We planned to use the mechanism and the measur-

ing system to carry out the veriﬁcation of the effec-

tiveness of the system for the rehabilitation of lower

limbs, and to examine the interaction between lower-

limb exercises, and the computer-based supervision

and control of medical rehabilitation. The perfor-

mance indexes used in (Smak et al., 1999; Carpes

et al., 2010) will be integrated to evaluate the lat-

eral asymmetry and the effectiveness of pedaling for

rehabilitation. Now, we are collecting normal sub-

jects (mainly university students) to carry out a full

test for the prototype. Then, we plan to investigate

the effect of rehabilitation from the viewpoints of

human-computer interaction, physiotherapy, exercise

psychology, etc. After the analysis, we plan to invite

HUCAPP 2017 - International Conference on Human Computer Interaction Theory and Applications

126

people with lower-limb injuries to test the effective-

ness of the system. Those results will be reported in

the near future.

ACKNOWLEDGEMENTS

This work was supported by Japan Society for the

Promotion of Science (JSPS) KAKENHI Grant Num-

bers 26350673, 16H02883, by the National Natural

Science Foundation of China under Grants 61473313

and 61210011, by the Hubei Provincial Natural Sci-

ence Foundation of China under Grant 2015CFA010,

and by the 111 Project, China under Grant B17040.

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