Designing Games to Help Train Children to Use
Prosthetic Arms
Lessons Learned from Developing Five Games
Peter A. Smith, Ph.D. & Matt Dombrowski, MFA
School of Visual Art and Design
University of Central Florida
Orlando, FL U.S.A.
[email protected], [email protected]
Abstract— Prosthetic Arms are often financially out of reach
for children. A single prosthetic can cost upwards of $40,000
USD and as children grow they may need multiple new arms
throughout a single year. Further, high end prosthetics can be
incredibly complicated allowing for articulated wrists and
individual finger movements, leading to a complex learning curve
that leaves many adults frustrated leading to lack of use of the
prosthetics. Limbitless Solutions, however, has applied low cost
3D printing to the task and has developed a simple to control
prosthetic arm for kids and the emerging world. This work
explores the use of video games combined with a custom
controller to train kids to use their new prosthetic arms before
they get them.
was a need for accessibility in video games. The International
Game Developers Association (IGDA) forms the Game
Accessibility Special Interest Group (SIG). The goals of this
group are to define the needs of the disabled and to develop
and support the creation of technology to help aid in equality
for disabled gamers. [2]
Keywords—Prosthetics, Training Games, Games for Health,
Custom Interfaces, Game Design
I. INTRODUCTION
Prosthetic Arms are often financially out of reach for
children. A single prosthetic can cost upwards of $40,000 USD
and as children grow they may need multiple new arms
throughout a single year. Further, high end prosthetics can be
incredibly complicated allowing for articulated wrists and
individual finger movements, leading to a complex learning
curve that leaves many adults frustrated leading to lack of use
of the prosthetics. Limbitless Solutions, however, has applied
low cost 3D printing to the task and has developed a simple to
control prosthetic arm for kids and the emerging world. The
limbitless arm cost closer to $350.00 USD to build [1]. This
work explores the use of video games combined with a custom
controller to train kids to use their new prosthetic arms before
they get them.
II. BACKGROUND
Limbitless designs arms that look like they come off the
page of a comic book, harking back to things like Iron Man,
Frozen, or Transformers. Allowing kids to not only regain the
use of an arm, but to feel cool doing it. The arms empower the
users both physically and mentally.
In 1997, the US Census states that 25.5% of the US
population suffers from these types of disabilities. [2]. There
Fig. 1. The Limbitless 3D Prothetic Arm [3]
In an effort to help children learn how to use their arms,
and to help strengthen muscles that will be used to control the
arm, a suite of training games was developed. According to
Huynh [4] accessibility for games can be categorized into two
groups. Specially developed software and equipment that can
assist the user with commercial games and, games that are
designed specifically for disability rehabilitation. These games
are designed for the latter, but the controller interface could be
used in either case. In 2009 a review of games for children with
physical disabilities showed success and 13 out of 16 studies
[5]. In a study in 2012 on leg amputees using training games
that incorporated a balance board the amputees performed
closely with other children of their own age after 4 weeks of
play [6]. In many cases with games research poor results can
be attributed as much if not more to bad game design then to
the ineffectiveness of games.
•
These games were designed to impart a wide variety of
game play options in an attempt to learn more about how this
type of game should be designed in the future. Many lessons
were learned through the internal playtesting process along the
way and will be incorporated into the games that are delivered
to children in the future.
•
•
III. THE GAMES DESIGNED AND LESSONS LEARNED
A. Game 1: Who Knows
Who Nose started as a test case to implement the controller
that was built to interface the prosthetic interface with a game.
The game tests a calibration sequence before gameplay and
gives an average strength. This is then used to calibrate the
other games.
Each user flexes differently depending on their strength.
One of the initial challenges was how to create an
individualized base line depending on the user’s strength level
or amputated area. Adults have different strength levels than
children have, therefore, having a game such as Who Nose
was an important starting point to the suite of games in efforts
to maximize user interaction. Who Nose is a very simple
concept with a very important purpose. This game, as of all
the games, is developed for children who have amputated
limbs.
The concept of the game is for the user, in this case the
child; to use their EMG recorded muscle contractions to lift a
finger into a nose and then on the next muscle contraction pull
items out of the nose. Items that are pulled out of the nose
range from a Lego block to a nosey prospector.
The game however does not match the users flexes 1 to 1.
Movement happens more as an animation than it does a
reaction to individual flexes. This proved to be a less than
ideal way to keep player attention on the game.
Fig. 2. Who Nose Calibration Screen
1) Design Elements that Worked Well
• Great calibration tool built in
• Easy to use
• Funny to kids
2) Lessons Learned
There needs to be a one to one relationship between
flexing and action on screen
There needs to be goals not just jokes
There needs to be an story to bring context
B. Crazy Meteor Cleaner
Crazy Meteor Cleaner is an Asteroids like game, where the
player takes on the role of a space pilot ridding an area of space
from asteroids. The arm controller is implemented as a fire
button allowing flexes to lead to shots fired from the gun.
One of the most noticeable successes from this game was
its familiarity with the user. Many users and onlookers of the
game immediately noticed its visual similarities to classic
arcade games. Another positive feature of the game was it was
easy to map flex to shoot. The controls were intuitive to its
users and the learning curve of the game was instant.
Longevity of play is a very important factor when
developing these games. These games are intended for training
purposes and for prolonged use. We want the user to stay in the
environment to learn and progress, but we also do not want the
user to become physically exhausted. Having a specific time
limit on the game is needed to avoid any chance of exhaustion.
Changes to game are needed. One solution was to limit the
game time to 90 seconds to make sure kids don't get tired, this
was a mistake. While 90 seconds might seem like a long time,
no one wants to stop playing at the end of this time.
The game controls also needed some work in regards to the
user finding them. The user easily found the movement
controls but the game also has bomb function. There is a need
to keep all the buttons together and easily accessed by one
hand, without moving it around the keyboard in this type of
game. In addition, the purpose of the game play is to creatively
incorporate the prosthetic EMG controller into the game play
itself. Currently in this game, nothing special about arm
controller that makes using the interface fun.
Fig. 3. Crazy Meteor Cleaner Game Play Screenshot
1) Design Elements that Worked Well
• game is very familiar to everyone
• easy to map flex to shoot
2) Lessons Learned
•
game limited to 90 seconds to make sure kids don't
get tired, this was a mistake should be infinite.
game has a bomb key that is never used
nothing special about arm controller that makes using
the interface fun
2) Lessons Learned
• easy to accidentally do a sustained function
• hard to get quick timing down between prosthetic
controller and keyboard
• Kids don't eat sushi usually so metaphor is wasted
C. Sushi Slap
Sushi Slap is a game that puts the player in the role of a
giant squid that is on the table ready to be served as sushi. The
squid can then slap attackers from 4 directions. The length of
the squid’s tentacles also provides an indication of the player’s
health. This is a fast paced and fun game to play.
D. Beeline Border Collie
In Beeline Border Collie the user becomes a leaping collie
hurdling over fence jumps and collecting apples on its way for
points. This is a side scrolling game must like the commercial
game Flappy Bird.
•
•
Character design plays a large role in the success of a
game. Creating an emotional connection with the user and the
game element is essential. Being these games were developed
for young children, the developers wanted to make sure the
character design appeals to the audience. The initial user group
found the character of a rouge piece of Sushi funny and
appealing. The cartoonlike movements and squash and stretch
of the character appealed the user group.
Sushi Slap also incorporated various successful controls for
the EMG based controllers. The game has different functions
for sustained and quick flexes. This allows the user to have the
ability for a more in-depth training experience. To address the
issue of possible exhaustion, game designers incorporated
small lulls, or breaks between waves provide a chance to rest to
the user.
The games art is very cute and is believed to be more
appealing to younger players. The game is also the easiest to
control. There is a 1 to 1 mapping between the player flexing
and the dog jumping. The dog jumps over fences and the game
can be played infinitely.
The game could however be more complex. In future
iterations there will be high and low fences that can be jumped
with stronger and shorter flexes. There will also be high gates
that the player must go under. Also, all of these games, but
especially Beeline Border Collie would benefit from a high
score table as it is very easy to compare your score with others.
Unfortunately, there are some concerns that kids do not eat
sushi and may not feel for the character the same way adults
might. Also, there is a power slap that can be used through a
sustained muscle contraction. This is a different way to use the
interface, but does not relate to a function on the actual arm
and is often accidentally used.
Fig. 5. Beeline Border Collie Introductory Screenshot
1) Design Elements that Worked Well
• Art is cute and non-distracting
• Simple game with no keyboard interaction
• 1 to 1 mapping between flex and jump very easy
2) Lessons Learned
• Game could be more complex like flex hard to high
jumps light for low jumps
• Game instantly resets on end and is difficult to tell
what happened
• Does not record high score.
Fig. 4. Sushi Slap Game Play Screenshot
1) Design Elements that Worked Well
• Characters are funny
• Has different functions for sustained and quick flexes
• Small breaks between waves provide a chance to rest
E. Smash Bro
Out of the initial suite of games, Smash Bro has gained the
most interest by the development team to go forward. The
concept of Smash Bro is very reminiscent of the classic
Midway game Rampage. Users play as a building smashing
monster who’s only goal is maximum destruction. The
monster smashes buildings, people and all of its surroundings
to gain the user points for the damage in the given amount of
time of the level. When demoed, Smash Bro, had not only the
longest time of gameplay, but also the most replay value
amongst the users.
This game seems to be a winner in that it is very easy to
use the flex in multiple ways. One for a sonic attack when the
player is not moving, the other for a smash when the player is
moving. Both do lots of damage to buildings with a 1 to 1
mapping to the controller.
Currently the biggest issues are with on screen heads up
display (HUD) elements being too small. The HUD sort of
melds into the background and when the game is over it
currently appears to have just stopped. This will be fixed in
future updates.
While the game might seem violent for kids, the violence
is handled in a light hearted way. There is an emphasis on
cartoon violence following the ESRB designation of violence
for E10+. This will be explained to parents when the game is
delivered to actual users.
•
Arrow keys are good depending upon which arm is in
the prosthetic
IV. CONCLUSIONS
Overall the games have been a huge success. While not
100% ready for user testing with the kids, the design team has
learned a lot about the way these games should be designed.
With a few tweaks a few of these games will make their way to
kids who will be able to use them to strengthen their muscles
and prepare for receiving their custom 3D printed prosthetic
arm. Dawson, Carey, and Fahimi [7] recommend that future
research focus on increasing measuring and recording of
performances throughout training and investigating how these
training tools are impacting treatment. In future work these
games will undergo immense scrutiny and will incorporate
measuring and recording techniques as well.
ACKNOWLEDGMENT
We would like to thank the team at Limbitless Solutions
Inc. for bringing us into their world of prosthetic arm design
and allowing us to be part of the magic. We would also like to
thank the students of the Spring 2016 DIG 4720 Casual Games
Production class for helping us explore the design space for
these games.
REFERENCES
[1]
[2]
[3]
Fig. 6. Smash Bro Start Screen
1) Design Elements that Worked Well
• Relationship between flex and action is very well
matched
• Multiple flex actions add to depth
• Game is fun to play
• Only needs allow keys beyond flex interface
2) Lessons Learned
• Cartoon violence is ok, but needs to be explained
• HUD needs to be easier to view especially when
game ends
• Needs a death sequence or game over screen
[4]
[5]
[6]
[7]
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http://limbitless-solutions.org/index.php/2015/07/01/alex/
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Online
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http://www.thingiverse.com/thing:408641
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