Pilot Study for Generating Dynamic Olfactory Field Using Scent Projectors Yasuyuki Yanagida, Masashi Kajima, Shunpei Suzuki, and Yuya Yoshioka Faculty of Science and Technology, Meijo University
ABSTRACT A technique for locally distributing scented air and controlling its direction of movement is proposed. By causing two vortex rings carrying scented air to collide with each other, a local distribution of scent can be achieved in free space. Thus far, however, the behavior of scented air after vortex collision has not been controlled. In this study, we propose a method for varying the moving direction of scented air after the collision by precisely controlling the timing and velocity when expelling vortex rings. We conducted an initial experiment to examine the feasibility of this method and found that direction control of the airflow after vortex collision can be achieved by adjusting the velocity of vortex rings. Keywords: Olfactory display, scent projector, vortex ring. Index Terms: H.5.1 [Information Interfaces and Presentation]: Multimedia Information Systems—Artificial, augmented, and virtual realities 1
INTRODUCTION
In virtual reality (VR), it is quite important to control the stimuli spatiotemporally for each sensory modality. Researchers have studied various methods of controlling olfactory stimuli spatiotemporally. For example, Yamada et al. [1] developed wearable olfactory displays to present olfactory information based on the user’s position. Matsukura et al. [2] developed “Smelling Screen” to provide scents carried by a wind and succeeded in aligning the wind position with the objects on a visual display. Yanagida et al. [3] developed “Scent Projector” to deliver scents through the air by using vortex rings without requiring a user to wear any special devices. Nakaizumi et al. [4] extended this method to locally distribute scent in air by colliding two vortex rings with each other. In the real world, scents are often carried by the airflow. From this point of view, Smelling Screen is a natural way to provide scents. However, their system was designed for a desktop scale, and the user was assumed to stay in front of a display panel or a screen. Here, we propose a method to produce a local, short-term airflow in free space by using the collision of vortex rings. We follow the method by Nakaizumi et al. [4], but with further focus on the angles and velocities of two vortex rings to enable directional control of local airflow after the collision. By using vortex rings, we expect to deliver scents locally in a larger space with smaller amount of scents being emitted, compared with methods using continuous airflow (wind). * 1-501 Shiogamaguchi, Tempaku-ku, Nagoya 468-8502 Japan
[email protected]
IEEE Virtual Reality 2013 16 - 20 March, Orlando, FL, USA 978-1-4673-4796-9/13/$31.00 ©2013 IEEE
In this study, we report our initial experiment to examine the feasibility of the proposed method. 2
PRINCIPLE
A scent projector makes use of the principle that a vortex ring can convey scented air and can travel relatively long distance without dispersion. In [4], Nakaizumi et al. proposed a method to intentionally break the vortex ring by colliding two rings with each other, for preventing a user from feeling as if he/she were suddenly hit by a blast of air and for delivering scents gently to the user’s face. Considering that scents are conveyed by airflow, it is necessary to control the direction of air drift after the collision. Thus far, we have not taken care of the direction in which the scented air drifts after the collision. In most cases, two vortex rings are expelled at equal velocity (Figure 1(a)). However, we noticed that we might be able to control the direction of drift if we set a difference between the velocities of the two vortex rings (Figure 1(b)). As each vortex ring has kinetic momentum to move forward, the air drift after the collision might follow the sum of the kinetic momenta of the two vortex rings. Thus, we predicted that we can change the direction of air drift if we provide different kinetic momenta to each of the two vortex rings. Scent projector (Air cannon) Vortex ring Same velocity
Collision Local distribution of scented air
(a) Scent projector (Air cannon)
Expelling the ring later
Expelling the ring earlier
Faster vortex ring
Slower vortex ring
Collision Controlling moving direction of scent distribution
(b) Figure 1: Method for controlling the moving direction of the local scent distribution. (a) Symmetric case: two scent projectors expel vortex rings of identical velocity simultaneously. (b) Asymmetric case: controlling the initiation time and velocity so that two vortex rings reach the target point simultaneously with different velocities.
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EXPERIMENT 1: HEAD-ON COLLISION
We first examined the case of a head-on collision to investigate the effect of setting different velocities for two vortex rings. We used a scent projector shown in Figure 2. This device can control the direction of a vortex ring by a pan-tilt mechanism. Vortex rings are expelled by pushing the back plane with a crank-piston mechanism, which is driven by a stepper motor. By specifying rate of the pulse sequence, the velocity of vortex ring can be controlled. (a) Collision angle: 150°
Figure 2: Scent projector used in the experiment.
Prior to this experiment, we calibrated the velocity of the vortex rings and the driving parameters of the scent projector. We selected the driving parameters so that the velocity of a vortex ring can be selected as 91 cm/s, 124 cm/s, and 164 cm/s at a point 75 cm in front of the aperture of the scent projector. We used fog to visualize the vortex rings, and recorded the collisions with two video cameras. When we let vortex rings with velocities of 91 cm/s and 164 cm/s collide, the faster vortex rings destroyed the slower ones and continued to travel. For the case of 124 cm/s and 164 cm/s, both vortex rings collapsed, and the fog distributed around the collision point. A larger amount of fog drifted in the direction of the faster vortex. 4
EXPERIMENT 2: COLLISION AT VARIOUS ANGLES
Next, we examined cases other than head-on collisions to investigate the effect for general situations. The alignment of experimental setup is shown in Figure 3. From the result of Experiment 1, we chose the combination of 124 cm/s and 164 cm/s to make the collapse of the vortices probable. We observed the drift of fog after the collisions at angles of 150°, 120°, and 90°. Scent projector (Air cannon) 164 cm/s at collision point 124 cm/s at collision point Collision angle
Figure 3: Alignment of Experiment 2.
The results are shown in Figure 4. For all collision angles, the fog drifted in the direction close to the faster vortex ring instead of drifting along the symmetric axis. This implies the direction of fog drift was affected by the difference in the vortex ring velocity.
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(b) Collision angle: 120°
(c) Collision angle: 90° Figure 4: Fog drift for various collision angles.
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CONCLUSION
We found that it is possible to control the direction of air drift after two vortex rings collide and collapse; this is expected to be applied for controlling olfactory space. This study is still in the initial phase, and more precise analysis is required to achieve accurate direction control of scent distribution. REFERENCES [1] [2]
[3] [4]
T. Yamada, S. Yokoyama, T. Tanikawa, K. Hirota, and M. Hirose. Wearable Olfactory Display: Using Odor in Outdoor Environment. Proc. IEEE Virtual Reality 2006, pages 199–206, March 2006. H. Matsukura, T. Yoneda, and H. Ishida. Smelling Screen: Technique to Present a Virtual Odor Source at an Arbitrary Position on a Screen. Proc. IEEE Virtual Reality 2012, pages 127–128, March 2012. Y. Yanagida, S. Kawato, H. Noma, A. Tomono, N. Tetsutani. Projection-Based Olfactory Display with Nose Tracking. Proc. IEEE Virtual Reality 2004, pages 43–50, March 2004. F. Nakaizumi, Y. Yanagida, H. Noma, and K. Hosaka. SpotScents: A Novel Method of Natural Scent Delivery Using Multiple Scent Projectors. Proc. IEEE Virtual Reality 2006, pages 207–212, March 2006.
