The Iron Horse - a sound ride

NordiCHI, October 19-23, 2002
Aesthetic Artefacts
The Iron Horse - a sound ride
Hanna Landin, Sus Lundgren and Johannes Prison
HCI/Interaction Design
IT University of Göteborg
Chalmers/Göteborg University
P.O. Box 8718
SE-402 75 Göteborg, Sweden
{it1laha, it1lusu, it1prjo}@ituniv.se
ABSTRACT
The Iron Horse combines modern technology with a childhood dream. It's a bike – but its sounds like a horse. By biking at different speeds, one can get it to walk, trot or gallop.
Sometimes it snorts, and it greets its owner and other iron
horses with a neigh. In the project, we explored how to
transfer the auditive expressions of horses into the art of
cycling using computational technology, to stretch the
boundaries of riding, cycling and interaction design. The
technology should be an inspiration for the cyclist's fantasy;
turning the playground into a jumping track, the way to
school into a race, and the cycle path into a piece of the prairie
well, since the sound changed in relation to the speed. Some
kids even had a throttle twist grip that made their bike sound
like a real chopper.
Others imagined that their bikes were horses. They gave
them names, pretended to groom them and fed them grass.
Sometimes they attached strings to the handlebars, using
them as reins. Unfortunately, the bikes were silent; the children had to emit horse sounds themselves.
To support the latter form of play, we came up with the concept of the Iron Horse, and we hope it will appeal to a wide
range of users.
Keywords
CONCEPT
Interactive Audio, Augmented Reality, Aesthetics, Bicycle,
Horse, Audial Expression, Sound
Our idea is to transfer some of horse's behaviors to bikes,
expressing them only as sounds, since we believe that the
audible expressions is a much better support for imagination, than simply putting a horse's tail on the bike. Such an
enhancement can be said to be in line with the concept of
Augmented Reality [Wellner et al. 1993]. We want to stimulate play, fantasy and creativity. Still, we think it is important, to follow the rules of reality in means of natural and
"logical" horse behavior, to support the conceptual model of
what a horse is and does. By measuring the speed of the
bike, sounds of different paces will be played: walk, trot and
gallop. Also, an Iron Horse will neigh and snort at certain
occasions, if it has a friendly personality for instance, it may
greet it's owner with a neigh. Obviously, this means that different Iron Horses have different personalities. Also, they
INTRODUCTION
When we were children, we often imagined that our bikes
were something else than bikes. Cards could be attached in
between the arms of the wheel to produce a spluttering
sound and by that the bike got an engine. This worked extra
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Aesthetic Artefacts
have herd instincts; if a group of Iron Horses trot, one has to
bike faster than usual to prompt one's own Iron Horse to
gallop. To encourage play, we have also come up with some
possible game applications for Iron Horses.
MAPPING HORSES TO BIKES
Horses make a lot of sounds. We briefly divided these into
three groups;
• Hoof sounds: Sounds made by the hoofs. This can either
be the sounds produced when a horse moves on different
grounds at different speeds, or when a horse kicks something, the wall of a stall for instance.
• Mouth sounds: Neighing, snorting, shrieking.
• "Other" sounds: Eating, drinking, grazing, lying down,
standing up, lashing their tail, urinating etc.
We have deliberately excluded almost all of the "other"
sounds from our application, since they do not occur while
the horse is ridden. Also, we have chosen to leave out
aggressive sounds like the kicking and shrieking sounds.
The remaining sounds (walking, trotting, galloping, neighing, snorting and tail-lashing) can be divided into two other
groups; those who the rider can affect (hoof sounds), and
those who the horse itself chooses to make.
These sounds can be mapped to riding a horse versus riding
an Iron Horse enhanced bike in the following ways:
• A rider can affect the speed of his Iron Horse by treading,
or the speed of his horse by impelling it. In both cases this
is reflected in the different gait sounds such as walk, trot
or gallop.
• A horse, or an Iron Horse, may choose to neigh or snort at
any time.
• A horse, or an Iron Horse, may choose to neigh, when it
encounters one of its kind. Also, it may choose to answer
to neighs it detects.
• Different horses, and different Iron Horses have different
temperaments; they are more or less likely to neigh, snort
and greet their riders.
• A horse, or an Iron Horse, that is part of a herd, wants to
move at the same speed as its comrades. I. e. if all other
Iron Horses trot, and someone increases the speed of her
Iron Horse, the moment when it starts to emerge galloping sounds is somewhat delayed.
• Two horses that are friends and that are left on a meadow
on a hot summer day, sometimes stand head to tail with
each others, whisking away flies from each other faces
with their tails. If two Iron Horses are parked together in a
similar way they will emerge sounds of lashing tails.
Initially, we had ideas about expressing the feeling of riding
a horse by having a moving saddle, but we abandoned this
due to safety and aesthetic reasons.
APPLICATIONS
One could imagine a lot of applications for Iron Horses;
ways to set up race tracks, dressage spplicstions, cowboy
games, circus applications, medieval tournament games etc.
Below, we describe one of the many possible applications.
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NordiCHI, October 19-23, 2002
The Horse Jumping Application
Symbolical poles are laid out on the ground. The height of a
fence is determined by the number of poles. By combining
the poles in different groups it's also possible to make out
different types of fences, i.e. double-, triple or other combinations. The height/number of poles and the type of fence
determines the speed that is needed to jump over the fence
without knocking any pole(s) down. By combining a number of different fences, one can design one's own track.
When riding a real horse on a real track there are several
aspects to take into account. For example, the rider has to
judge how many strides the horse should make between two
fences to clear the second one. This implies that the rider
might have to extend or collect the canter to position the
horse right in front of the fence. It is also the rider who
decides when the horse should take off.
This is mapped to the Iron Horse's Horse Jumping Application with the help of the speed of the bike and the number of
revolutions with the pedals. The take off and horse being off
ground is mapped by the position of the pedals. This means
that to be able to clear a fence the rider must ride over the
fence at the right speed, depending of the height and type of
the fence, and with the pedals in the right position, namely
on the same level. Further the rider might come into a situation where he/she has time/distance left to decide whether to
treadle another revolution before jumping the next fence.
Just as in real life hearing either a horse landing or a horse
landing together with the sound of falling poles can conclude the result of the jump.
An Iron Horse and its rider approaching a fence with the
pedals in the correct position.
Design Considerations
A rider can improve his or her skills by practicing/playing a
lot with these applications. In real life, a horse would
improve its skills as well, when practicing. We have chosen
to abandon the horse metaphor at this level, since we do not
want to turn the Iron Horse into some kind of Tamagochilike toy [Kohn]. We don't want the Iron Horse owners to
feel forced to take care of/feed/train/groom their Iron Horse
NordiCHI, October 19-23, 2002
Aesthetic Artefacts
unless they themselves choose to make this a part of their
play; there should be no obligations associated with the Iron
Horse. Thus, no such needs or functions have been implemented (cf. the idea of using non-distractive and non-interruptive sounds in the Listen Reader [Back et al 2001]).
• The horse jumping application: The poles contain radio
transmitters, whose signals are picked up by the Iron
Horse's receiver. There is an accelerator sensor on the
pedals to measure if they are in the right position.
Also, the applications don't keep any track of scored points,
the time it takes to jump a track and the like. There are two
reasons for this. The first is that such track keeping would
impose rules onto the play, rules that the players should be
able to decide themselves. The second is that we want the
computer to be invisible; making it keep track would force
the user to regard it as a computer rather than a natural part
of play, since the computer would have to communicate this
output in a more traditional computer-like way.
Since this project was an assignment in design of aesthetic
computer artifacts, we spent a great deal of time considering
the aestethetic qualities of the Iron Horse. Our main focus
has been to create a rich audial expression without inconsistencies, feeling that there is a certain twist in leaving the
visual expression of the bike unchanged. We feel that this
application, like many other computer enhanced toys (Barney the Dinosaur [Strommen 1998], Tamagotchis etc) is an
important part of Augmented Reality, since it introduces the
almost magical qualities of ubiquitous computing in a very
direct way.
SYSTEM DESIGN
The Iron Horse consists of a number of sensors that send signals to a BX24-chip. The chip processes the signals and
transfers them to a Java program running on a laptop. The
program does some processing and then plays the appropriate sound through two loudspeakers. The current prototype
supports the following functions:
• Gait sounds: By placing magnets on the bikes spokes and
a magnetic field sensor on the front fork, the rotation speed
of the wheel can be measured.
• Random neighing and snorting: Which neighing or
snorting sound is played, depends on the current speed.
• Snorting when impelled: Magnets are placed on the pinion, near the pedals, together with another magnetic field
sensor. If the rider hasn't been threading for a while, and
starts again, the Iron Horse is likely to snort.
DISCUSSION
Future work might include development of new applications
(a race track application for instance), and the old ones
could be expanded. The horse jumping application for
instance, could be made more complex if the rider also has
to stand up in the saddle when jumping, and has to tread the
bike in-between fences; this would be equal to controlling
the number of strides.
ACKNOWLEDGEMENTS
Above all, we'd like to thank our fourth group member
Magnus Johansson. We'd also like to thank Peter Ljungstrand for great help with the prototype, and Lars Hallnäs
and Johan Redström for discussions about aesthetic matters.
REFERENCES
• Greeting its owner: The Iron Horse's key has a radio
transmitter with a three-meter range, that sends a signal to
the Iron Horse. When the Iron Horse picks up this signal,
with its receiver, it may neigh to greet its owner.
1. Back, M., Cohen, J., Gold, R., Harrison, S., Minneman,
S. (2001) "Listen Reader: an electronically augmented
paper-based book." Proceedings of CHI 2001, ACM
Press, April 2001.
• Neighing when rearing: By placing an accelerometer on
the crossbar we can measure the bikes angle towards the
gravity of earth. If a large and quick change is done the
Iron Horse may neigh because it "rears".
2. Kohn, M. The History of the Tamagotchi, http://
www.yorku.ca/courses/sosc1080/sem05g1/history.html
(Last checked 2002-04-02)
Functions that may be a part of future Iron Horse systems
can include:
3. Strommen, E. (1998) When the Interface is a Talking
Dinosaur. ACM Press/Addison-Wesley Publishing Co.
New York, NY, USA, pages: 288 - 295 Series-Proceeding-Article
• Gait sounds depending on ground : By analyzing the
sounds from the wheels, one can map this to different
grounds, playing gait sound like "trot on grass" etc. This
may be facilitated by having only one hoof sound per type
of ground, playing it in different patterns to produce the
sounds of different gaits.
• Herd instincts and greetings: Each Iron Horse will have
a radio transmitter and receiver. Thus, each Iron Horse's
current behavior can be transmitted to other Iron Horses
nearby, and they can act on it.
4. Wellner, P., Mackay, W., Gold, R.,(eds) (1993) Back to
the Real World. Special Issue on Computer Augmented
Environment. Communications of the ACM, Vol. 36,
no. 7, pp 24 - 97, ACM Press
5. Kiley-Worthington, M. (1987), The behaviour of horses
in relation to management and training, J. A. Allen,
London
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