TAMA: Development of Trajectory Changeable Ballfor Future Entertainment
Tomoya Ohta
University of Electro-Communications

Shumpei Yamakawa
University of Electro-Communications

1-5-1, Chofugaoka, Chofu, Tokyo, Japan

1-5-1, Chofugaoka, Chofu, Tokyo, Japant_ohta@vogue.is.uec.ac.jp

shumpei@vogue.is.uec.ac.jp

Takashi Ichikawa
University of Electro-Communications

Takuya Nojima
University of Electro-Communications

1-5-1, Chofugaoka, Chofu, Tokyo, Japan

1-5-1, Chofugaoka, Chofu, Tokyo, Japanichikawa@vogue.is.uec.ac.jp

tnojima@nojilab.org

ABSTRACTIn this paper, we propose a ball interface “TAMA”(Trajectory chAnging, Motion bAll; “tama” means a ball inJapanese) that can change its own trajectory dynamically.
Conventionally, it is impossible to go against the laws ofphysics. However, if the trajectory of the balls can bechanged during flight, that virtually means balls can fly
against physical laws. This should enhance the pleasure ofball-related games such as baseball, basketball, juggling, etc.
In this research, we used the force of compressed gas fromwithin the ball itself to change the ball trajectory.
Previously, we developed the ball prototype equipped witha gas-jet unit. However, the primal prototype was too heavy
to use in amusement. Additionally, there was no control of
the timing of the jet and it was wired for power supply. In
this paper, we introduce the latest prototype of TAMA,
which trims the weight and adds new functionality. We
discuss the feasibility of this system throughexperimentation in changing the ball’s trajectory during
downward flight.

INTRODUCTION

Digital technology has made our life convenient andcomfortable. Recently many researchers have applied it into
balls in order to make ball games more enjoyable andexciting [8, 19]. However, there are a few approaches that
focused on the ball’s actual motion. Considering variationsof breaking balls and of feint techniques, clearly the ball’s
actual motion is one of the important factors for an
enjoyment of ball games. Therefore, we have attempted toenhance an enjoyment of them by changing the ball’s
motion. Figure 1 is one of the images that shows ourconcept.
(a)Author Keywords(b)

Ball; entertainment; motion sensing; jet pressure; sports.
ACM Classification Keywords

H.5.2. Information interfaces and presentation: User
Interfaces: Interaction styles.

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AH '14, March 07 - 09 2014, Kobe, Japan
Copyright 2014 ACM 978-1-4503-2761-9/14/03…$15.00.
http://dx.doi.org/10.1145/2582051.2582101(c)

Figure 1. Concept of TAMA (Trajectory chAnging, MotionbAll), generating a special physical effect.

In the figure, a player is throwing a ball. (a) At first, the ballgoes rightward. (b) But suddenly, the direction of the ballchanges to leftward. (c) The direction of the ball changes torightward again. Such unusual trajectory is often describedin the world of digital games and animations, as a kind of“special effects”. However, it is quite difficult to generatesuch special effects in the real world.
In this study, we propose a ball with a gas-jet system thatcan change its trajectory “TAMA” (Trajectory chAnging,
Motion bAll; “tama” means a ball in Japanese) [6]. The
force that derived from the reaction of a jet of compressedgas can change the ball’s trajectory (such as Figure 2).
Development of a ball that can control its own motion
makes conventional sports and amusements more excitingand enjoyable. In this paper, we report the detail of the
prototype systems and experimental results.

Figure 2. The ball ejecting compressed gas.

RELATED WORKS

Much research has been done to enhance an enjoyment ofball games by using various digital technologies. In thisarea, it can be categorized into three types of research.
Applying digital technology to game fields, or to balls, or toboth. Ishii et al. proposed an augmented table tennis byapplying digital technology to game field. They added
microphones to the ping-pong table to detect where the ball
hit on the table. By using the proposed system, theysucceeded in generating visual and acoustic effects to thegame field based on the position of the ball [7, 20]. Mueller
et al. have proposed the sports beyond the players' field. By
using the screen projected the visual of the life-size
opponent, they allowed the match of the table tennis or air
hockey over a distance [11, 12]. BallCam! is a typicalexample of second research category, which applies digitaltechnology into balls. BallCam! is capable of generating astabilized point-of-view from a spinning ball with only one
embedded camera [1, 10]. It is expected that we could
vividly watch the video of the sport from the ball. Jeong etal. have developed a virtual catch ball system using
SPIDAR-H, a kind of wire-based haptic display [9]. Thatsystem enables a person for doing catch ball with virtual
characters. A ball is integrated with the SPIDAR-H so as tocontrol ball’s physical status, such as speed, trajectory,
which is necessary when the virtual character throws it. For
third research category, the project "Bouncing Star" is atypical study. Izuta et al. developed a ball that includes
various sensors and LEDs, as well as a special game fieldwith a high-speed camera and a projector [8]. The ball andthe game field can generate a certain visual effect,
according to the motion of the ball. Sphero [18] is a ballthat can change its motion on the ground via Smart Phones.
The concept is quite similar but it could not change
trajectory in the air, in spite of the fact that most ball-related
sports games throw balls in the air. Nguyen et al. havedeveloped a small, sphere-shaped satellite that could change
its trajectory by using micro gas-jet[14]. However, thesystem is aimed to be used for satellites in the space, thenthe reaction force is quite weak to be used to change thetrajectory of the conventional balls on the earth. Shootballby Sugano et al.[19] is a novel ball game that uses acamera-and-display-surrounded game field and a sensorintegrated ball. Cameras in the game field and a wirelessshock sensor in the ball can detect the motion of the ball.
Displays around the field shows goal areas or special areathat has a certain function. Then players try to shoot thoseareas according to their game strategy with that sensorintegrated ball. As previous works show, developing a
digitally integrated game field is one of the methods toenhance an enjoyment of ball games. However, that
requires players to prepare such special game fields, whichshould reduce the chance to play. It should be a great
benefit to ball game players that the game could be played
anytime, anywhere. Then in this research, we focus on
integrating digital technology into balls.
Up to now, many researchers have tried to apply digitaltechnology to the balls. Such research can be largely
grouped into two. The first group is integrating multiple
sensors, including cameras, to make balls as a new kind of
the sensing system. "PUYO-CON"[4] is ball-shaped input
interface that can sense grasping situation. It has a soft body,so it can perceive direct touch and force with which it isheld and how it is deformed under pressure while in use.
GoalRef is the real-time ball tracking system using thewireless communication tip RedFIR. It helps the referees
make the correct decisions on the goal in soccer [2].
94FiFty is a sensors integrated basketball [1]. It canmeasure several information of playing such as boundcounts, spin rate and so on. Players can develop skills
rapidly by those information. Pfeil et al. presented athrowable panoramic camera using 36 mobile phone
cameras. The ball-shape camera allowed capturing thecomplete panoramic image [16]. The second group isadding certain effects such as visual, auditory and motion to
the balls. Rasamimanana et al. also added sensors to a ball,but added sound effects to the sport or game in response toactivity [17]. There are few researches that focused on theball’s motion. Halme et al. and Michaud et al. developedball-shaped robots that can control the rolling motion [3,11]. But these can control the motion only the ground.

PROTOTYPES OF TAMAAs shown above, there is much research that haveaugmented the ball and sports. However, very few focus on
motion of balls. When considering the variety of breaking
balls in various conventional ball games, the trajectory of
the ball should be one of the essential points that could
affect an enjoyment of ball games. In our research, wedevelop a novel ball that focuses on its projectile motion
during flight. Control of the ball motion through the aircontributes to more exciting entertainment contents.

An early experimental system was equipped with acompressed gas-jet unit [6]. However, this was simple instructure with a mounted unit inside a hollow ball, so it wasvulnerable to impact shock. So, for use in games, thematerial of the ball was changed to sponge to increase its
impact resistance. This is the first prototype named “TAMAI”.

TRAJECTORY CHANGING BALL MOTION

In sports, ball trajectory is one of the most importantelements. For example, in baseball, breaking balls generateinteractive strategies between the pitcher and the batter.
Thus, changeability of ball trajectory mid-flight contributes
considerably to make various entertainments moreenjoyable for not only players, but also the spectators.
Dynamically motion-controllable ball enable us some newinteractions to the ball. The following are such examples.


Increasing varieties of breaking ballsControlling ball speed or flying distance

Adjusting ball trajectory to goal or targets.

And we envision this system for use in the sport as ahandicap or support of players' ability. In the match
between players that have gaps of ability or one's physique(e.g. adults vs. children), using this system can bridge thosegaps. In other words, a motion-controllable ball can realize
sports where all players can compete all out.
Now, we suggested a sport application using the developedball. In baseball, for example, it can make the match more
exciting and tactical. This ball can change the vector of the
motion. It allows new breaking balls (e.g. uprising, comingback) and controlling the ball speed or distance of flying. In
a match between professional players, it improves thesophistication of the gamesmanship by expanding thevarieties of gameplay. When it is a match between
professional players and non-professional ones, this system
could serve as a handicap. For example, it aids or disrupts
the player's power by the controlling ball’s speed and flying
distance, and/or makes throwing some breaking balls easy.
Handicaps affecting the game directly make the match very
exciting without hampering play mechanics on either side.
This system can enhance the enjoyment for all of players
and audiences.
Moreover, this ball contributes to the creation of the newentertainment contents. If we can control the ball motion atwill by equipping an input interface inside the ball, creationof new tactical sports or physical game that relies on player
tactics can be expected.

TAMA I

System Configuration

This prototype consists of the gas tank (taken from a toygun, Walther P99: MARUZEN), a servomotor (HSG5084MG: Hitec Multiplex Japan) and an Arduino nano.
These are placed within the sponge ball. The control of thegas jet was achieved by holding down a button which
activates a connected servo-motor (Figure 3). This
prototype’s internal configuration and system of jet are
shown in Figure 4. The weight of this prototype is 627g.

Figure 3. The gas ejection switch is controlled by the servo
motor (Left: normal state, Right: ejection state)

The gas tankwith a servo motor

Jet

Figure 4. System configuration of TAMA I.
TAMA IITAMA I had no function to control the jet timing, so these
could not change the motion vector arbitrarily. In addition,
TAMA I was heavy because of the rechargeable gas tank. It
required to use lighter material. Therefore, we made a newprototype named TAMA II that has sensors to measure its
own position. Improved points of this prototype are shown
below.



Detection of orientation, the prototype can control thejet timing based on itThe gas - jet unit was downsized and weight was
decreased by changing the system

Controlling the quantity of ejected gas is enabled bycontrolling the duration of opening or closing thevalve

Data of Measurement
Weight [g]Maximum Force [N]Duration of Ejection [s]Impulse [Ns]
Impulse-Weight Ratio [Ns/kg]

We have succeeded in reducing the weight of 249g fromTAMA I. Figure 5 shows the system configuration in the
prototype.

TAMA II
378
6.80
1.4
5.14
13.6

Table 1. Comparison data of two prototypes.

System Configuration

TAMA II consists of an output component that ejects
compressed gas and an input component that get
information from sensors. An Arduino nano is equipped in
the sponge ball, and ejection is controlled based on
information from the input component. The output
component consists of a compact inflator (MARUNI
Industry) for bicycles, a CO2 cartridge (BARBIERI) and a
DC motor (SCL16-30: NAMIKI PRECISION JEWEL) to
open or close the valve of the jet. The input component
consists of a 6DoF IMU (SEN-10121: Sparkfun) and apotentiometer to measure the rotation of the motor tocontrol the quantity of ejected gas. In addition, this ball canreceive commands from the PC by the Bluetooth module.
The total weight of this prototype is 378g, including16g
consumable CO2 cartridge.

TAMA I
627
13.24
1.4
6.93
11.1

Potentiomet
er
DC

CO2

motor

Cartridge

Open
Close

or

Arduino Nano
BluetoothmoduleIMU
Motor Driver

DC
motor
Inflator
Jet Nozzle

BASIC FEATURES OF TAM I AND TAMA II

Table 1 shows the basic features of TAMA I and TAMA II.
The Figure 6 shows the preliminary setup to measure theejection force of the gas, simply putting a pressure sensor
seat in front of the nozzle. In TAMA II, it was lighter thanprevious ones by installation of the new compressed CO2
jet system but the jet pressure decreased. However, themost important requirement is to change the ball’s
trajectory. From this point of view, impulse-weight ratio
should be the most important factor. As shown in Table 1,
the ratio of TAMA II is higher than TAMA I. So from here,
we will conduct further evaluation of TAMA II. Figure 7
shows the transition of the force of the ejection gas of thetwo prototypes.
Detailed evaluation of TAMA II

Sponge Ball

CO2
Cartridge

Figure 5. System configuration in TAMA II.

A pressure sensor

Ex1: Jet Test in Air and Sensing Ball Orientation

In this experiment, the prototype was set to eject the gas
only a situation when the ball detected its free-fall and theangle of the jet nozzle to the horizontal plane was up to 30
degrees. At first, the ball was projected up to about 2 meters
high. When it has met both of requirements of descent anddirection, the compressed gas was ejected. We calculated its
trajectory from values of the acceleration sensor in two
conditions: the case that ejected and the case that did not.
The result of the calculation and the value of sensors areshown in Figure 8 and Figure 9.

Jet

Figure 6. A preliminary setup to measure
the force of the gas ejection

TAMA I

timing of the jet is controllable based on the information on
its orientation.
In this experiment, the point of landing was displaced about
1.2 meters long by the gas jet. This proved the feasibility ofthis system.

TAMA II

Figure 9. Sensing the angle and control the jet timing.
Ex2: Relationship between cycles of use of a cartridge andthe force of the gas ejection
Figure 7. Ejection force transition.

Figure 8 shows the ball’s trajectory from ascent to landing.
A continuous line shows the trajectory with gas jet, and thedashed line shows the trajectory without gas jet. At the xorigin, the ball was tossed upwards. X-axis shows theabsolute value of the horizontal displacement amount fromthe origin. Y-axis shows the height of the ball from theground. It is evident that the gas jet had the ball changing
the falling trajectory.

Figure 8. Amount of change of trajectory.

Figure 9 has three data curves that show the verticalacceleration, relative ball angle to the horizontal plane andthe timing of the jet from the top. When the ball angle wasless than 30 degrees and decreasing its acceleration was
detected, compressed gas was ejected. It shows that the

Changing a ball’s trajectory requires enormous energy. In
spite of the fact, the gas in the cartridge is quite limited.
Then, we conduct an experiment to find relationshipbetween cycles of use of a cartridge and the pressure force.
In this experiment, we use a new CO2 cartridge. Then ejectgas 4 times, each with a duration of 500 milliseconds.
Between the cycles, we made an interval for about an hourto set the temperature of the cartridge back to normal. Thisis because, the cartridge becomes quite cold because ofvaporizing heat after each ejection. That low temperature
directly influences the pressure of the ejected gas.

Duration [msec]
Figure 10. Relationship between cycles of use of a cartridge
and the force of the gas ejection.

Figure 10 shows the result of the measurement. At second
ejection, it was measured that relatively great pressure
while it decreased from first. At third and fourth ejection,
the pressure was very weak. Considering with actual
throwing tests, it is expected that one cartridge can change
the ball’s trajectory only once or twice under theseexperimental conditions.
UNWIRETHE
APPLICATIONSSYSTEMTOWARD

However, the amount of decrease seems small. Then, we
confirm the ability of changing the trajectory of the unwired
version of TAMA II by actually throwing it up.
A rubber plate anda pressure sensor

ACTUALIn the prototype shown above, it needs moderate electricity
to open the valve. The required power was supplied via thewire from AC adapter. It is obvious that unwiring is quite
valuable for ball type devices such as TAMA II. Using abattery as a power source is inevitable when considering an
actual application. In the latest prototype, we havesucceeded in completely unwiring it by equipping withlithium-polymer battery (3.7V, 1000mAh) and a power
circuit. The total weight of the ball is 404g (including a
CO2 cartridge).

Jet

A slide rail to reduce friction
Figure 12. A setup to measure the thrust power.

1st Ejection[N]

AC
Battery

[ms]

Power
circuitFigure 13. Thrust power transition.
Throwing up experiment

Lithium-polymer
battery
Figure 11. Unwired version of TAMA II

When changing the power source from an AC outlet to abattery, it often brings several problems such as weight andpower. To change the trajectory of the ball, the valve of theCO2 cartridge should be turned open fully and instantly toacquire enough thrust power. Then we performed anexperiment to confirm the effect of changing power sources.

In this section, we performed a throwing up experiment toconfirm that this prototype has enough potential to change
its trajectory. We recorded the appearance of the change ofthe ball trajectory when the ball ejected at the peak position.
Figure 14 is divided frame pictures captured from the video.
The displacement between a circle around the ball and acenter line shows the ball trajectory certainly changed by
the gas jet. In spite of the increase of the weight,
appearance of the change of the ball’s trajectory compares
favorably with wired version.
DISCUSSION

Effect of changing power source to the thrust power

Figure 12 shows a setup to measure the thrust power. The
result is shown in Figure 13. The figure shows arelationship between time and thrust power. The blue dottedline indicates force transition when using AC as a powersource. The red line indicates the same case when using abattery as a power source. From the result, by changing thepower source from an AC outlet to a battery, the thrust
power slightly decreased. This is because the lack of thepower of the battery, it was unable to fully open the valve.

In this paper, we developed and improved the gas-jet ball
prototypes. In the latest prototype, the weight of the ball islighter, and jet efficiency is higher than in the previous
prototype. The prototype cans sense its motion and attitude.
It enabled the control of the timing of the jet without
sending a command signal. The experiment showed that thejet system can change the trajectory of the ball mid-flightby sensing its orientation. This use of TAMA can imply alarge addition of ball-related games.

Figure 14. Appearance of the change of the ball trajectory (upward: a conventional ball, downward: the gas-jet ball).

In spite of the remarkable features of TAMA discussed
above, current configuration has two big problems yet to besolved. One issue is pressure and temperature related
problem. In this system, once the gas is ejected, thetemperature of the tank becomes low due to loss of heat due
to gas thermodynamics. This low temperature weakens thepower of jet flow. Cartridges we currently use havecapacity for two times of gas jets, if the temperature can be
maintained after first gas jet. Currently, we solve thisproblem by exchanging CO2 cartridges after ejection every
time, which is not cost effective. Another issue is related tothe speed of ball’s motion. Ideally, when ejecting gas tochange its trajectory, the jet vector should be controllable.
However, the direction of the jet nozzle in the current
system changes during motion because the gas jet nozzle
position is fixed. In spite of the fact, the current system isrelatively slow when detecting orientation, thus cannot ejectgas at an appropriate timing.
To provide novel entertainment property in ball-related
games by using TAMA, several methods are considered. In
this chapter, we will discuss three types of methods. The
first one is, using TAMA as a kind of attractive special
effects in games for prospectors. To discuss this, we assume
the situation that the ball’s trajectory change in an unusual
way, triggered by players’ command input such as special
gestures. Such kind of special effects are often described inanimations and cartoons, but have never occurred in the realworld. Then, changing balls’ trajectory itself has potential
to be used for attraction for prospectors. Visual and acoustic

special effects are also preferable for this purpose. The
second is using TAMA for inducing game players to missthe handling of balls. If the ball’s trajectory changes justbefore the player catches it, the player should miss catching
the ball. This could be used for a kind of handicap. The
experimental results show that total amount of change ofthe trajectory by using TAMA is enough to induce players
to miss such handlings. To assure inducing such failure forplayers, faster trajectory change is preferred. Higher
ejection pressure is one of the solution of this issue.
However, the governmental law prohibits people who do
not have an appropriate license to use cartridges with highpressure. The pressure of the CO2 cartridges which used inthis system is almost near the limitation that allowed to be
used by people who do not have the license. Therefore,
instead of using higher pressure, increasing the number ofcartridges is the affordable solution to increase the weightof flow. In addition, improving gas-ejection response
should also be a solution for this issue. To comply with thisdemand, a faster valve that allows large amount of flow toearn enough reaction force is necessary. When achieved
faster trajectory change, the trigger for the gas ejection
should be considered. Current prototype systems use
accelerometers to initiate gas ejection, which is relatively
hard to control the timing of the gas ejection. Then, insteadof the accelerometer, conventional Kinect-based, orcamera-based gesture recognition systems should also be
available for this purpose. In addition, our research member
proposed a novel sensing system named PhotoelasticBall[15] that could measure the magnitude and direction of
applied force on the ball’s surface. This PhotoelasticBall isaimed to detect slight hand gesture that is applied to theball’s surface. This means, when players catch a ball, they
could input appropriate command before they throw the ballwithout looking the ball. This could help the player tocontrol the timing of gas ejection without being known byother players around him. The third method to be discussed
here is using TAMA for active assistance for players. In
this case, precise trajectory control should be required. For
example, gas ejection adjust the trajectory of the ball to becaught by a player, just before when the player almost fails
to catch the ball. To comply with this issue, timing,
direction and duration of gas ejection should be precisely
controllable to navigate the flying ball to a certain place at a
certain time to be caught by the player.
CONCLUSION

In this paper, we report developments of the ball that canchange its trajectory. We introduced two prototypes anddiscussed their capabilities. The latest prototype is lighterand can sense its own orientation. Using a CO2 gas-jet unit
contributes to the system by making it smaller and lighter.
At the same time, it has enough power for generating
driving force. We succeeded in changing the free fall
trajectory of the ball by ejecting the compressed gas. Also,
we succeeded in the control of timing of jet based on theinformation from sensors on the ball. In the future, user
tests will be conducted for evaluating the digitalization ofball-related games.
REFERENCES

1.Basketball Training Aids 94FiFty.
http://www.94fifty.com/ (Accessed: 19 Jan 2014).
2.GoalRef - Fraunhofer Institute for Integrated Circuits.
http://www.iis.fraunhofer.de/en/bf/ln/referenzprojekte/goa
lref.html (Accessed: 19 Jan 2014).
3.Halme, A., Schonberg, T. and Yan Wang. Motion control
of a spherical mobile robot. In Proc. IEEE Workshop on
Advanced Motion Control 1996, IEEE (1996), 259-264.
4.Hiramatsu, R. PUYO-CON. In Proc. SIGGRAPH ASIA
2009, ACM Press (2009), 81-81.
5.Horita, K., Sasaki, H., Kitani, K. and Koike, H.
Experiencing the ball’s POV for ballistic sports. In Proc.
AH 2013, ACM Press (2013), 128-133.
6.Ichikawa, T. and Nojima, T. Development of the motioncontrollable ball. In Proc. UIST 2010, ACM Press (2010),
425-426.
7.Ishii, H., Wisneski, C., Orbanes, J., Chun, B. andParadiso, J. PingPongPlus: design of an athletic-tangibleinterface for computer-supported cooperative play, In
Proc. CHI 1999, ACM Press (1999), 394-401.

8.Izuta, O., Sato, T., Kodama, S. and Koike, H. Bouncing
Star project: design and development of augmented sports
application using a ball including electronic and wirelessmodules. In Proc. AH 2010, ACM Press (2010), Article
No.22.
9.Jeong, S., Hashimoto, N. and Sato, M., A novel
interaction system with force feedback between real andvirtual human: an entertainment system: "virtual catchball". In Proc. ACE 2004, ACM Press (2004), 61-66.
10.Kitani, K., Horita, K. and Koike, H. BallCam!: dynamic
view synthesis from spinning cameras. In Proc. UIST
2012, ACM Press (2012), 87-88.
11.Michaud, F. and Caron, S. Roball, the Rolling Robot.
Autonomous Robots Volume 12, Kluwer Academic
Publishers (2002), 211-222.
12.Mueller, F.F., Cole, L., O’Brien, S. and Walmink, W.
Airhockey over a distance: a networked physical game tosupport social interactions. In Proc. ACE 2006, ACM
Press (2006), Article No.70.
13.Mueller, F.F., Gibbs, M., Vetere, F. and Agamanolis, S.
Design space of networked exertion games demonstrated
by a three-way physical game based on Table Tennis. In
Proc. CIE 2008, ACM Press (2008), Article No.36.
14.Nguyen, H., Köhler, J. and Stenmark, L. The merits ofcold gas micropropulsion in state-of-the-art space
missions. In Procs. the 53rd International Astronautical
Congress,(2002),IAC-02-S.2.07.
15.Nitta, K., Sato, T., Koike, H. and Nojima, T.
PhotoelasticBall: A touch detectable ball using
photoelasticity. In Proc. AH 2014, ACM Press (2014),
TBA.
16.Pfeil, j., Hildebrand, K., Gremzow, C., Bickel, B. andAlexa, M. Throwable panoramic ball camera. In Proc.
SIGGRAPH Asia 2011, ACM Press (2011), Article No.4.
17. Rasamimanana, N., Bevilacqua, F., Bloit, J., Schnell,N., Fléty, E., Cera, A., Petrevski, U. and Frechin, J. The
urban musical game: using sport balls as musicalinterfaces. In Proc. CHI EA 2012, ACM Press (2012),
1027-1030.
18.Sphero, Orbotix Inc. http://www.gosphero.com(Accessed 20 Feb 2014).
19.Sugano, Y., Ohtsuji, J., Usui, T., Mochizuki, Y. andOkude, N. Shootball: the tangible ball sport in ubiquitous
computing. In Proc. ACE 2006, ACM Press (2006),
Article No.31.
20.Xiao, X., Bernstein, M.S., Yao, L., Lakatos, D., Gust, L.,
Acquah K. and Ishii, H. PingPong++: Community
Customization in Games and Entertainment. In Proc.
ACE 2011, ACM Press (2011), Article No.24.