Development and design of spinning tops that do not fall over aiming
at improvement of quality of life
Shigeo HIRANO1, 2, Susumu KISE2, Sozo SEKIGUCHI2
Kazuya OKUSAKA2 and Tsutomu ARAKI3
1

Professor emeritus, Tokyo City University

1-28-1 Tamazutsumi, Setagaya Ward, Tokyo 158-8557, Japan
2

Artner Co. Ltd

Sumitomo Nakanoshima Building 2F, 3-2-18 Nakanoshima, Kita Ward, Osaka City
530-0005, Japan
3

Professor emeritus, Tsukuba University of Technology
4-3-15 Amakubo, Tsukuba City, 305-0005, Japan1

rs4775hirano@ybb.ne.jp, 2kise@artner.co.jp, 3tutaraki@yahoo.co.jp
ABSTRACT

Using the fingers stimulates brain nerve cells and activates the brain functions.
Therefore, it is important for the elderly to use their fingers in their daily lives. We propose
the use of spinning tops, which are familiar to Japanese people, as welfare devices that can
improve the quality of life of the elderly by preventing the decline of physical function,
dementia, and motor disorders and improving the health of the elderly.
Spinning tops have been familiar since early childhood. They come in a variety of shapes
and are spun using various techniques. Anyone can enjoyably play with spinning tops witha simple operation using the fingers. Therefore, a continuous effect is expected. From theviewpoints of the prevention of dementia in the elderly and rehabilitation of those who sufferfrom it, playing with spinning tops can lead to an improvement in their quality of life. In
addition, spinning tops can prevent the elderly from feeling isolated mentally and sociallybecause of the communication generated as they play with the spinning tops. For effective
rehabilitation, continuity is required. To this end, the concept is that the motion of spinning
tops provides the chance for discovery and fun.
In this study, we focused on spinning tops that do not fall over even when they stop rotating,and developed a theoretical equation to describe this phenomenon. In the development anddesign of such spinning tops to be used in rehabilitation and play, the coefficient of friction
was measured to examine the theoretical equation. In addition, the success rates ofremaining standing after they stop rotating under various conditions of factors such as
friction, material, and shape of the spinning tops were compared. The issues to be resolved
and future prospects were discussed.
Keywords: quality of life, welfare devices, rehabilitation, using the fingers, play and delight

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1.

INTRODUCTION

We propose the use of spinning tops, which have long been familiar to Japanese, as welfare
devices for encouraging the elderly to use their fingers in their daily lives. To promote thecontinuous use of spinning tops as rehabilitation devices, we developed the motion theoryof a special type of spinning top that does not fall over even when it stops rotating. Moreover,
we designed and manufactured such a type of spinning top.
In this study, the current issues of population aging, the need for long-term care, and theprevalence of cerebral vascular diseases in the Japanese society are discussed first. Then,the characteristics of spinning tops played using the fingers and their potential as welfare
devices are described.
For the development and design of spinning tops that do not fall over, theoretical equations
are formulated to describe the principle of motion. Spinning tops are manufactured withdifferent dimensions and materials to examine the theoretical equations and compare various
conditions. In the examination of the theoretical equations, the coefficient of friction ismeasured. In addition, the success rates of the tops remaining standing after they stop
rotating under various conditions, such as the friction, material, and shape of the spinning
tops, are compared1),2)．
The relationship between the theoretical equations and the factors of spinning tops that do
not fall over is clarified in this study. Also, a survey is conducted to evaluate theeffectiveness of the spinning tops developed and designed in this study and to find theirpoints of improvement as welfare devices for the elderly. Finally, the issues to be resolved
and future prospects are discussed.

CURRENT STATE OF POPULATION AGING AND THE NEED FOR LONG–TERM CARE IN JAPAN, AND PROPOSAL OF SPINNING TOPS THAT
DO NOT FALL OVER AS WELFARE DEVICES
The elderly (65 years and above) accounted for 26% of the total population in Japan in 20153).
Japan has become an aging society, in which one in every four persons is elderly. Although
the total population is declining, the elderly population is slightly increasing. As a result,the population aging rate is increasing yearly.
Generally, cerebral vascular diseases are the major reasons for the long-term care need ofpeople aged 65 to 84 years. With advancing age, debility and dementia also become major
reasons for such a need3).
The long-term care need is defined as the condition assumed to require constant and longterm care for a certain period of time in all or some of the basic activities of daily life suchas bathing, excretion, and eating due to physical or mental limitations3).
Hand control is closely related to the brain. Recently, it has been revealed that hand use
increases cerebral blood flow and stimulates the brain. Also, hand movement brings aboutchanges in the brain. This is because of synaptic plasticity, which is the ability of neurons
in the brain to bring about changes in the connections between neuronal networks or the
The 6th Ratchasuda International Conference on Disability 2019
Ratchasuda College of Mahidol University, Thailand, 15-17 May 2019transmittance of impulses in response to stimulation1). For example, patients with finger
paralysis due to brain disorder can regain finger motion through rehabilitation.
In this study, we propose the use of spinning tops that do not fall over as welfare devices. It
is important for the elderly to always use their fingers to prevent the decline of hand andfinger functions. However, the elderly often experience difficulty in continuing finger
rehabilitation exercises2).
Therefore, we focused on spinning tops that can encourage the elderly to use their fingers
while playing. The elderly will become curious and continue to enjoy playing with thespinning tops if the motion of spinning tops provides the chance for discovery and fun. To
this end, we develop and design a special type of spinning top, namely, the spinning top that
does not fall over even when it stops rotating.

PRINCIPLE OF MOTION OF SPINNING TOPS
3.1

Principle of precession

Figure 3-1 shows the principle of forces acting on a spinning top. A spinning top is supportedby the supporting point on the floor. Gravity acts in the direction that causes the spinning
top to fall to the floor. The gravity, in combination with the centrifugal force generated byrotation, causes precession. The spinning top rotates with an angular velocity of precession
ω and an angular velocity around the axis of the spinning top Ω. The moment of inertia
around the axis is Iyy and the angle between the axis of the spinning top and the line
perpendicular to the plane is θ.
The torque of centrifugal force acting on the axis is expressed as T=IyyΩωsinθ. When theheight of the center of gravity of the spinning top is l, the torque of gravity acting in the
direction that causes the spinning top to fall to the floor is expressed as N=Mglsinθ.
Precession occurs and the spinning top does not fall over when the two torques acting on thespinning top (T and N) are equal to each other4),5).
Therefore, the condition for precession is given as follows.

I yy  sin   Mgl sin 
3.2･･･････(1)Speed of stand-up motion of spinning tops

The torque needed for stand-up motion is generated so as to counteract the frictional force
generated by the rotation of a spinning top. In time, the spinning top starts to rotate to stay
upright.

When the coefficient of dynamic friction is μ, the moment around the center of gravity due
to the frictional force, N1=μMgl, acts in the direction that reduces θ. By expanding theequation of motion, the speed of stand-up motion of a spinning top is given as follows4),5),6).
The 6th Ratchasuda International Conference on Disability 2019
Ratchasuda College of Mahidol University, Thailand, 15-17 May 2019

 

Mgl
I yy 

Figure 3-1.

3.3･･･････(2)Principle of forces acting on spinning top

Deceleration in rotation

When the distance between the axis of a spinning top and the ground contact point is r, themoment around the axis owing to the frictional force, N2=μMgr, acts in the direction that
decelerates Ω. The equation of motion for angular acceleration in a rotating spinning top is
as below, assuming time t 4),5).


Mgr

t
I yy

･･･････(3)From Eqs. (2) and (3), the speed of stand-up motion increases, but the angular velocity
decreases as the coefficient of dynamic friction increases. When the spinning top stands
upright, it rotates with negligible deceleration of ω because r is sufficiently small. Also, thespeed of stand-up motion increases as the position of the center of gravity is lowered and themoment of inertia increases.
From the above, it is assumed that a spinning top does not fall over when Eq. (1) holds as ωand θ approach zero.
3.4

Moment of inertia

The moment of inertia indicates the mass in rotational motion. It shows how difficult it is
to change the rotational motion. The moments of inertia in the x-, y-, and z-axes are given
as follows.

The 6th Ratchasuda International Conference on Disability 2019
Ratchasuda College of Mahidol University, Thailand, 15-17 May 2019



2



2



2

2



･･･････(4)2

･･･････(5)･･･････(6)I xx   mi y i  z ii

I yy   mi z i  xi
i

I zz   mi xi  y i

2i

From Eqs. (4)–(6), the moment of inertia is found to increase with the mass and the distancefrom the axis of rotation.
Because a spinning top is a rotating object, Iyy affects the rotation of the spinning top when
the axis rotates. Also, Ixx and Izz indicate how difficult it is for an object to rotate in the
upward and downward directions at the center of gravity. In the rotation of a spinning top,small-amplitude and short-period motions caused by disturbance and deflection overlap withthe period of precession. These short-period motions are called nutation. The rotation of aspinning top is stabilized when the equation for the moment of inertia Ixx = Izz holds. A large
gap between Ixx and Izz causes nutation and, as a result, the spinning top loses its balance6).
3.5

Kinetic energy of rotational motion

The circumference of radius r is 2πr. When the rotational speed is ν, the velocity v is 2πrν.
Therefore, the kinetic energy of rotational motion is given as follows6).

E
3.6

1
1
Mv 2  M 2r 2  2I 2 2
2
2･･･････(7)Frictional force

The above theoretical equations show that the principle of motion of spinning tops is largely
affected by frictional force. In this section, the principle of frictional force is explained.
When an object with mass M is pulled by force P, the frictional force acts in the direction
opposite to that of P. When the normal force is N and the acceleration of gravity is g, thefrictional force F is generally expressed as follows.

F  N  Mg･･･････(8)Here, μ is the coefficient of friction, which is a dimensionless quantity. The frictional force
F is therefore determined by the normal force N. When the force P equals the frictional
force F, the object does not move even if force is being applied. The frictional force in sucha state is called the static frictional force Fs. F = P holds at first; however, F < P holds when
the object is pulled by a force larger than that at which the object starts moving. The static
frictional force Fs reaches its maximum at the moment when the object starts moving, whichis called the maximum static frictional force Fsmax. Also, the frictional force that acts on the
The 6th Ratchasuda International Conference on Disability 2019
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object after it starts moving is called the dynamic frictional force Fd. The dynamic frictional
force Fd is smaller than the maximum static frictional force Fsmax.
μ is the ratio of the normal force N to the frictional force F expressed as follows.



F
F

N Mg

･･･････(9)4.
4.1

BASIC DESIGN

Reference dimensions

The equations describing the principle of motion of spinning tops show that the factors thatsignificantly affect the rotation of spinning tops are 1) the frictional force, 2) the position of
the center of gravity, and 3) the moment of inertia. It is also assumed that the size of theground contact area of the ground contact axis is important for spinning tops to remain
standing after they stop rotating.
The differences in frictional force on various measuring planes as well as the differences in
the mass and the forces acting on spinning tops due to the differences in the material andshape of spinning tops were examined in the experiments.

Figure 4-1.

Reference shape of spinning tops that do not fall overTable 4-1.

Reference dimensions

Part nameDimensions [mm]Diameter of handle axis

d1

3.0

Diameter of main body

d2

19.0

Diameter of ground contact axis

d3

3.5

Total height

h

23.5

The 6th Ratchasuda International Conference on Disability 2019
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Height of handle axis

h1

7.0

Height of parallel part of main body h2

4.0

Height of parasol-shaped part

h3

9.5

Height of ground contact axis

h4

3.0

The reference dimensions of a spinning top were set and used as the standard for comparison
during the analysis of spinning tops. The dimensions of spinning tops used for shapecomparison were determined by referring to the reference dimensions. Figure 4-1 shows thereference shape of spinning tops that do not fall over. The spinning tops that do not fall overmust remain standing when they stop rotating. To this end, the ground contact axis of thedesigned spinning tops has a large ground contact area and a small fillet radius. Table 4-1
shows the reference dimensions.
4.2

Selection of materials

Spinning tops that do not fall over are significantly affected by the frictional force andmoment of inertia. The equations described above show that the mass is related to thoseeffects. Also, the frictional force varies depending on the specific gravity and frictional
property of materials. Therefore, the success rates of spinning tops of various materials werecompared. Considering the characteristics of materials, such as excellent workability, low
price, and density homogeneity, brass (C3604), bronze (CAC406C), and acrylic resin(PMMA) were used.
4.3

Determination of dimensions

To develop the theory for spinning tops that do not fall over, spinning tops were
manufactured with different shapes, including those with various lengths of the groundcontact axis and heights of the center of gravity. Spinning tops of different materials andshapes were designed using SolidWorks. Figures 4-2 and 4-3 show the spinning tops ofdifferent materials and shapes. Spinning top 1 was made of brass (C3604), spinning top 2
was made of bronze (CAC406C), and spinning tops 3–9 were made of acrylic resin (PMMA).

(1) C3604 (2) CAC406C (3) PMMA
Figure 4-2.

(4) (5)Figure 4-3.

Spinning tops made of different materials

(6)

(7)

(8)

(9)

Spinning tops (PMMA) of different shapes

The 6th Ratchasuda International Conference on Disability 2019
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4.4

Manufacturing of spinning tops

A high-speed precision lathe (MK-860, Yamazaki Mazak Corporation) was used for
manufacturing spinning tops. The processes for manufacturing spinning tops that do not fall
over are divided into the following two parts: 1) machining and cutting of the handle axis
and 2) tapering of the ground contact axis and main body.

5.
5.1

EXPERIMENT AND RESULTS

Measurement of coefficient of friction

The coefficient of friction depends on the type of object being studied and its state. The
coefficient of friction was measured on 1) Kent paper, 2) newspaper, and 3) Japanese paper.
The dynamic frictional force Fd and the coefficient of dynamic friction on Kent paper were
160 N and 0.32, those on newspaper were 170 N and 0.34, and those on Japanese paper were
150 N and 0.30, respectively.
5.2

Comparison of friction

The theoretical equations show that the frictional force and shape can significantly affect therestoring force of a spinning top. Therefore, we spun a top (spinning top 1 in Fig. 4-2) 50
times at a certain angular velocity on different measuring planes and determined the successrate of the top to remain standing after it stopped rotating. The cases in which the spinning
tops moved away from the center of the measuring plane or did not rotate were not counted.
As a result of the comparison of friction on different measuring planes, the success rates for
those measuring planes were found to be 1) 16% for Kent paper, 2) 48% for newspaper, and3) 80% for Japanese paper.
5.3

Comparison of materials

In the comparison of materials, the mass, the forces acting on spinning tops, and the successrates of the tops to remain standing were examined using spinning tops made of different
materials. We spun spinning tops of the same shape but different materials (spinning tops
1–3 in Fig. 4-2) 50 times on a sheet of Japanese paper placed on a horizontal surface. The
rotation of the spinning tops was recorded using a superhigh-speed camera (HSV-500C3)
and the success rates of the tops to remain standing after they stopped rotating were
determined. The cases in which the spinning tops moved away from the center of themeasuring plane or did not rotate were not counted. Table 5-1 shows the position of thecenter of gravity l [mm], the mass M [g], the moments of inertia Ixx and Iyy [g･m2], therotational speed n [rpm], the rotation time t [s], and the success rate [%] obtained by
calculation and the comparison of materials.
5.4

Comparison of shapes

In the comparison of shapes, the mass, the forces acting on spinning tops, and the successrates of the tops to remain standing were examined using spinning tops of different shapes.
As in the comparison of materials, we spun all tops 50 times on a sheet of Japanese paper
placed on a horizontal surface. The rotation of the spinning tops was recorded using a
superhigh-speed camera (HSV-500C3) and the success rates of the tops to remain standing
after they stop rotating were measured. Table 5-2 shows the position of the center of gravity
The 6th Ratchasuda International Conference on Disability 2019
Ratchasuda College of Mahidol University, Thailand, 15-17 May 2019l [mm], the mass M [g], the moments of inertia Ixx and Iyy [g･m2], the rotational speed n [rpm],
the rotation time t [s], and the success rate [%] obtained by calculation and the comparisonof shapes.
Table. 5-1

Results of comparison of materials

Ixx [g・m2] Iyy [g・m2]

Topsl [mm]M [g]n [rpm]t [s]Success rate[%]

①

12.12

19.48

561

680

1363

2.00

64

②

12.12

19.94

575

696

1224

3.43

62

③

12.12

2.45

71

86

3000

9.78

80

Table 5-2.
Tops
①
②
③
④
⑤
⑥
⑦
⑧
⑨

6.1

Ixx [g･m2]
561
575
71
56
74
446
281
8143
6183

Results of comparison of shapes

Iyy [g･m2]
680
696
86
77
86
630
454
9863
8721

n[rpm]

6.

DISCUSSION

1363
1224
3000
3333
2727
1579
1364
600
682

t[s]
2.00
3.43
9.78
11.12
10.09
11.20
10.84
6.77
9.24

success rate [％]
67
62
80
76
96
76
100
64
96

Discussion on comparison of materials

Table 5-1 shows that the success rates of spinning tops 1 and 3 to remain standing are higher
than that of spinning top 2. This seems to be due to the fact that the rotational speed increases
and the effect of nutation decreases as the material mass decreases.
When different materials are used, the changes in the properties of the materials do not affectthe success rates of the tops to remain standing, but only the change in material mass affects
the rotational speed and moment of inertia. As the mass decreases, the rotational speed
increases and the rotation is stabilized. At the same time, there are cases in which spinning
tops hit the wall and are flicked off because of the decreased moment of inertia. It is therefore
necessary to clarify the relationship between the rotational speed and the moment of inertia,
which are affected by the changes in the mass.
6.2

Discussion on comparison of shapes

The 6th Ratchasuda International Conference on Disability 2019
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The height of the center of gravity and the moment of inertia of a spinning top largely affectthe success rate of the top to remain standing after it stops rotating. Because the taper angle
θt’ and the height of the center of gravity are inversely proportional to the moment of inertia
I, it is impossible to improve the success rate of the spinning top by adjusting only the taper
angle θt’.
The success rate increases when the height of the center of gravity of the spinning top islowered by decreasing the height of the ground contact axis h4. The rotation is considered
to be stabilized because the moment of inertia Ixx significantly decreases as the taper angle
θt’ increases. The taper angle θt’ is a reliable index for determining the success rate.
The success rate increases when the moment of inertia increases along with the increase in
the mass. Similarly to the results of comparing the materials, the mass and moment of inertia
are inversely proportional to the rotational speed and rotation time. As a result, the change
in the size does not affect the success rate, and only the change in the mass affects therotational speed and moment of inertia.
6.3

Effects of ratio of moment of inertia

The ratio of moment of inertia is obtained using Eqs. (3) and (4). Figure 6-1 shows therelationship between the success rate and the ratio of moment of inertia. The success rateincreases with the inertia moment ratio. In addition to the height of the center of gravity andthe moment of inertia, the ratio of the moment of inertia is useful in evaluating the stabilityof rotation.

success rate[％]

Figure 6-1.

6.4

Ratio of moment of inertia and success rate

Effects of angular acceleration

The angular acceleration of spinning tops is obtained from Eq. (3). Figure 6-2 shows therelationship between the success rate and the angular acceleration. In this figure, the successrate is higher when the negative value of the angular acceleration is closer to zero.
6.5

Effects of speed of stand-up motion

The speed of the stand-up motion of a spinning top is obtained using Eq. (2) and comparedwith the success rate. The success rate increases as the speed of stand-up motion decreases.
This result shows that the success rate is higher when it takes a longer time for a spinning
top to stand up, namely, when the period of precession is longer.
The 6th Ratchasuda International Conference on Disability 2019
Ratchasuda College of Mahidol University, Thailand, 15-17 May 2019success rate[％]

Figure 6-2.
6.6

Angular acceleration of rotation and success rate

Effects of diameter of ground contact axis

Spinning top 8 has the same taper angle as spinning top 6, but it has a larger diameter of theground contact axis. As a result, the height of the center of gravity is lower and the successrate significantly increases. The success rate of spinning top 8 is high without showing any
proportional relationship with what?. This may be because the effects of torque acting on
the spinning top when it stops rotating are reduced by the small height of the center of gravity
and the large ground contact area. Let us first focus on the small height of the center ofgravity. The torque of centrifugal force acting on the axis of rotation is expressed as
T=IyyΩωsinθ. The torque of gravity acting on the spinning top is expressed as N=Mglsinθ.
Because the torque N includes the height of the center of gravity l as part of the function,
this torque decreases as the height of the center of gravity is decreased. Also, because
spinning top 8 has a large ground contact area, the frictional force acting on the groundcontact area is large enough that the spinning top does not fall over.
6.7

Issues to be resolved and future prospects

The spinning tops that do not fall over after they stop rotating are largely affected by the
moment of inertia. The stability of rotation can be evaluated by obtaining the ratio of Iyy to
Ixx. Also, the deflection of the axis of rotation decreases when the convergence of angularacceleration is moderate.
The measurement in this study was not quantitatively accurate because we spun the spinning
tops with our fingers and, as a result, the rotational speed varied widely.
Friction is a very important factor in the rotation of spinning tops. In this study, we measured
the coefficient of friction and substituted it into each theoretical equation to examine thesuccess rates of the tops to remain standing after they stop rotating, as well as the forces
acting on them. However, in the actual rotation of a spinning top, the ground contact area
comes into contact with the measuring plane at a point. Therefore, the coefficient of friction
varies widely depending on the surface roughness as well as the presence of an oxide film,
an adsorbed film, and contamination. The conditions also change as the ground contact areaof the spinning top becomes worn.
In the future, we will address the above issues, set appropriate values of the coefficient offriction and rotational speed, and clarify the effects of the moment of inertia, torque, andprecession on the success rate of spinning tops.

The 6th Ratchasuda International Conference on Disability 2019
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7.
7.1

MEASUREMENT OF A EFFECTIVENESS

Survey for measuring effectivenessSpinning tops with a large handle axis easily fall over owing to the large deflection causedby the effects of the moment of inertia. Therefore, ideal spinning tops that do not fall overshould have a handle axis of small diameter and length.
However, in order for people to easily hold a spinning top with their fingers, the diameterand length of the handle axis must be sufficiently large. In the design of spinning tops that
do not fall over as welfare devices used by the elderly, it is necessary to evaluate both thespinning tops themselves and their functions, as shown in Fig. 7-1. Although the spinning
tops themselves are evaluated by experiments and analysis, their functions must be
evaluated by measuring their effectiveness (Fig. 7-2).

Diameter of handle axis easy to hold
Diameter of handle axis actually designed

Diameter ofhandle axis
[mm]

Ideal diameter of handle axis forspinning tops that do not fall overFigure 7-1.

Design of handle axis

Ideal spinning tops

Evaluation of spinning topsthat do not fall overEvaluation of functions

Experimental and analytical

Effect measurement

Figure 7-2.

Design of ideal spinning tops

To determine the effectiveness of the spinning tops designed and developed in this study,
we requested the elderly to use these spinning tops. The following four points were
examined.
1.Do the spinning tops that do not fall over provide the chance for discovery and fun?
2.Are the product elements of the spinning tops, such as ease of holding, size, and design
quality, appropriate?
The 6th Ratchasuda International Conference on Disability 2019
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3.Can the continuous use of the spinning tops that do not fall over be expected?
4.Can the spinning tops that do not fall over be used as welfare devices?
In February 2017, we asked 28 elderly people (20 males and 8 females) aged 62 to 72 years
to use the spinning tops that do not fall over. The questionnaire sheet consisted of 10 items
concerning the four points described above. Each item was rated on a three-point scale.
Figure 7-3 shows the spinning tops used in the measurement of effectiveness. Table 7-1
shows the dimensions of those spinning tops. Table 7-2 shows the questionnaire items usedin the measurement of effectiveness and the obtained responses

Figure 7-3.

Spinning tops used in measurement of effectiveness

Table 7-1.

⑩⑪

d1[mm]
3.0
3.0

Table 7-2.

d2[mm]
49.0
49.0

d3[mm]
3.5
3.5

Dimensions of spinning tops
h[mm]
38.0
42.0

h1[mm]
18.0
22.0

h2[mm]
4.0
4.0

h3[mm]
13.0
13.0

h4[mm]
3.0
3.0

Questionnaire items used in measurement of effectiveness and responses(scores: ◎, 3; ○, 2; △, 1).
Questionnaire items

1.Were you surprised when you saw
the motion of the spinning tops?
2. Were they easy to spin?
3.Were they easy to hold with the fingers?
4. Were you satisfied with the rotation time?
5. Was the size appropriate?
6. How was the design quality?
7. Was the weight appropriate?
8. Would you like to try spinning them
repeatedly?
9. Would you tell other people about them?
10. Did you enjoy playing with them?
The 6th Ratchasuda International Conference on Disability 2019
Ratchasuda College of Mahidol University, Thailand, 15-17 May 2019Men
(N=20)
Indicatethe full
score
33

Women
(N=8)
Indicatethe full
score
32

28
28
28
26
25
26
29
29
27

Men and Women(N=28)
Total
Average
score
score
65

2.32

26
24
24
25
24
21
28

54
52
52
51
49
47
57

1.93
1.86
1.86
1.82
1.75
1.68
2.04

30
27

59
54

2.11
1.93

7.2

Discussion on measurement of effectivenessAs shown by the results of the questionnaire (Table 7-2), the spinning tops that do not fall
over provided many chances for discovery and fun to the elderly. Also, the score for thequestion “Would you like to try spinning them repeatedly?” was high, which means that thecontinuous use of spinning tops can be expected. In addition, the spinning tops were highly
evaluated as a communication tool that encourages the elderly to share the fun with others.
The action of spinning a top using the fingers, the visual excitement caused by following the
motion of a spinning top, and the thought-provoking surprise significantly stimulate the brain.
Also, the continuous use of spinning tops can be expected. From the above results, spinning
tops are considered effective welfare devices.
However, the scores for product elements including the design and functions were low. The
score for the question “Did you enjoy playing with them?” was not very high.
The reason for these low scores is probably be the lack of visual appeal of the spinning tops
used. The popular spinning tops that are familiar to us are colorful ones such as Edogoma,
whereas the spinning tops we manufactured are colorless (PMMA).
We will carry out further analysis to better understand the properties of the spinning topsthat do not fall over. Our goal is to improve the quality of those spinning tops as welfare
devices that can be continuously used by the elderly. To this end, we would like to makethe spinning tops more appealing by improving their ease of holding, size, and ease ofspinning as well as improving their design quality including their color and compactness.

8.

CONCLUSION

１．We propose the use of spinning tops, which have long been familiar to Japanese, as
welfare devices for encouraging the elderly to use their fingers in their daily lives. To
promote the continuous use of spinning tops as rehabilitation devices, we developed the
motion theory of a special type of spinning top that does not fall over. Moreover, we
designed and manufactured such a type of spinning top.
２．The principle of motion of spinning tops that do not fall over after they stop rotating
had not been established. Therefore, we formulated theoretical equations to describe theprinciple of motion. Spinning tops of different dimensions and materials were manufactured
to examine the theoretical equations and compare the success rate under various conditions.
３ ． The results of comparison experiments, as well as the relationship between thetheoretical equations and the success rate of spinning tops that do not fall over, were shownin this study. The issues to be resolved and future prospects were also discussed.
４．A questionnaire survey was conducted to evaluate the effectiveness of the spinning tops
developed and designed in this study and to identify points of improvement in theirapplication as welfare devices for the elderly.

The 6th Ratchasuda International Conference on Disability 2019
Ratchasuda College of Mahidol University, Thailand, 15-17 May 2019

The spinning tops that do not fall over after they stop rotating are significantly affected by
the moment of inertia. The stability of rotation can be evaluated by obtaining the ratio of Iyy
to Ixx. Also, the deflection of the axis of rotation decreases when the convergence of angularacceleration is moderate. In future studies, we will set appropriate values of the coefficientof friction and rotational speed and clarify the effects of the moment of inertia, torque, andprecession on the success rate of spinning tops.
９.

REFERENCES

1) Kisou Kubota: Hand and Brain,Kinokuniya, (1982).
2) Kisou Kubota: Itirou Miyai;The Rehabilitation Treatment Judged From a Brain,
Kodansha Publishers, (2005).
3) Cabinet Office, Yearly report about the situation of the aging and the situation of theimplementation of an old social measure 2017.
4) Yoshihiko Otuki: Chessman and Spin,Kyoritsu Shuppan, (1978).
5) Takao Sakai: Story of Dynamics, Three Beautiful Print Company, (1987).
6) Morikazu Toda: Science of a Frame, Iwanami Shoten, (1980).

The 6th Ratchasuda International Conference on Disability 2019
Ratchasuda College of Mahidol University, Thailand, 15-17 May 2019