Remote-controlled scent system for virtual reality applications

143

Remote
-
controlled scent system for virtual reality applications


E. C. Tan, C. H. Vun
and

A. Wahab


School of Computer Engineering, Nanyang Technological University,

Nanyang Avenue, Singapore 639798, Singapore.


asectan@ntu.edu.sg


Abstract:
An electro
mechanical system which can be programmed to press a selected small bottle to
emit scent has been developed. The system is controlled by a multimedia PC which in turn receives its
activation signals from a remote source. The remote controller is attached t
o a virtual reality system
which provides the scent
-
related visualization.


Keywords:
Scent system, remote
-
controlled, virtual reality.







Introduction


Consider a virtual reality (VR) system in which a
user is able to wander in a scenic garden. Apar
t
from the visual sensation that arises from
beautiful flowers, flying butterflies and birds,
there may also be the audio effect of bird singing
and running water. However, that is not all. With
the development of a PC
-
controlled scent system
[1], the abil
ity to smell the real scents from
various flowers has become a reality.


This paper describes an enhancement in [1] so
that it can be used for VR applications. The
electromechanical scent
-
emitter can be
incorporated with the VR system to provide the
extra
sensory euphoria. The signal to activate the
releasing of a required scent comes from the
remote controller attached to the VR hand.



Scent actuatot system


It is shown in Fig. 1. The dispenser unit consists
of a mechanical puncher using a linear solenoid

to depress the atomizer of a bottle that contain the
scent or fragrance, and a rotating turn
-
table
operated by a stepper motor [3].























Dispenser Unit


Motor Driver Board


PC



Fig. 1. The scent actuator system







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In Fig. 2, the rotating motion [2] of the turn
-
table
which can hold 10 bottles (perfume
-
bottl
e size)
will select the fragrance and the depression
motion of the linear solenoid will emit the
fragrance from the bottle. The linear solenoid can
be easily activated by supplying 24 VDC to it
while the stepper motor can easily be controlled
using a micro
-
controller or stand
-
alone PC [4].


A small electric fan is also installed close to the
turn
-
table. It will be activated for 15 seconds
after a scent has been emitted for 30 seconds in
order to disperse the fragrance upon a scene
change. The duration in
each case can be varied
according to the application at hand.


The remote
-
controlled system



The remote
-
controlled system consists of two
parts.


A. Receiver module at PC end



This module is interfaced with the PC through
the serial port (RS
-
232S) [4].

The most crucial
component of this module is an optical device,
which must be able to detect any infrared
radiation [5], [6]. The detected infrared radiation
must then be converted into some form of
electrical signal to be recognized and readable by
the P
C.


Two choices are available for this component, a
phototransistor or a photodiode. We choose the
former but the electrical signal generated by the
phototransistor is very weak. Hence, an amplifier
circuit is included to boost the signal. Since the
receiv
er module will only receive trains of square
pulses, and signals transmitted via infrared
radiation are subtler than noise, in order to retain
the shape of the received signals as much as
possible, a comparator circuit is used for signal
shaping. These wan
ted signals are then fed to the
central processing module of the PC.


T
he actual receiver circuit consists of two major
parts: the infrared detecting circuit and the
comparator circuit. Whenever an infrared
radiation of sufficient intensity is shined on th
e
phototransistor, the phototransistor will be turned
on and operates in the saturation mode allowing
current to flow through the 10K resistor
connected to its emitter. The voltage drop across
the collector and emitter is around 0.5V. Hence,
the voltage at

point A will be around 4.5V, and is
then fed to the positive input of the LM311N
comparator.


B. Transmitter module at VR end



This module consists of a device that emits beam
of infrared radiation [1
-
3] whenever it is
activated. The only possible device

to be used is
an infrared emitter. Because of the wide usage of
infrared in our modern technology, infrared
emitters are readily available from various
semiconductor manufacturers. The physical
appearance of an infrared emitter is identical to a
normal li
ght emitting diode. The amount of
infrared radiation is largely dependent on the
amount of current flowing through the emitter.












Fig. 2. The rotating turn
-
table with actuator


actuator

Linear Sol
enoid

Stepper Motor

Place
bottle
here



145

To emit infrared radiation of very high intensity,
pulses used to turn on the infrared emitter must
have a very n
arrow duration, in the range of
microseconds. Since a reasonable range of
intensity is expected, a pre
-
amplifying circuit is
included in this module to boost the amount of
current flowing through the infrared emitter.
Signals from the central processing mo
dule,
which are also pulse trains representing
commands for controlling remote devices, will
be inputs to the pre
-
amplifying circuit. The
infrared emitter will then be turned on or off
according to the transition in a pulse train.





The actual

transmitte
r circuit consists of a high
gain Darlington transistor and a pair of infrared
emitter. The operation is very simple. When a
signal of sufficient voltage and current is applied
at the base of the Darlington, the Darlington will
be turned on, allowing curre
nt to flow through
the 1


resistor and the infrared emitters. The
transmitter is interfaced with a keypad encoder
circuit [7] shown in Fig. 3. The VR
-
hand selects
the required fragrance by pressing a number (or a
graphical object such as a type of flower)
on the
keypad.






































R1 Vcc


R2 DA


R3 DB


R4 DC


R5 DD


Osc DE


KM OE’


C4 AV


C3 C1


GND C2

Vcc

MM74C923

To Micro
-
controller

4x4 Keypad

0.1

F

Fig. 3. Keypad encoder circuit

1

F

Virtual
-
reality applications


Apart from a garden setting as mentioned in
Section I, the scene can be an or
chard in which
various types of fruit trees are grown. Tropical
fruits such as ‘durians’ usually give out a very
aromatic and pungent smell when they are ripe
but are still on the trees. Many fruit scents are
readily available in small bottles and can be
p
laced on the rotating turn
-
table in Fig.2. A user
fitted with VR gear can wander in the orchard
and enjoy or learn the various wonderful fruit
scents according to his or her choices. Other
scenes such as seaside, bush
-
fire with smoke,
volcano
-
eruption, etc
. can be designed and
customized with appropriate scents.


The system can of course be used for educational
purposes. An entomology lesson in a jungle will
allow a student to smell scents from various
insects. A cooking lesson will allow a student to
smell

the various types of food. The list can go
on and on.


Conclusions


We have developed a remote
-
controlled scent
emitter that can be incorporated with a VR
system to provide a user with an extra sensory of
smell associated with the object of visualization.


References


[1]

E. C. Tan, A. Wahab, G. H. Goh and S. H.
Wong, “PC
-
controlled scent system’,
IEEE
Trans. on Consumer Electronics
, Vol. 44,
No. 1, Feb. 1998, pp.130
-
136.


[2]

I. M. Gottlieb,
Electric Motors and Control
Technique
, New York, McGraw Hill,
1994.


[3]

T. Kenjo,
Stepping Motors and Their
Microprocessor Controls
, Oxford,
Clarendon Press, 1984.


[4]

L. C. Eggebrecht,
Interfacing to the IBM
Personal Computer
, SAM, 1990.


[5]

W. Nunley and J. S. Bechtel,
Infra
-
red
Optoelectronics: Devices and Appl
ications
,
New York, Marcel Dekker, 1987.


[6]

E. L. Dereniak and G. D. Boreman,
Infra
-
red Detectors and Systems
, New York, John
Wiley, 1996.


[7]

MAX233 Driver Specification
, Maxim,
USA, 1995.


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