Figure 1. Overview of U-brella

U-brella: A Portable Umbrella-shaped Device for Vibrationizing Information

Yuichi Fujii , Fumio Kishino , Kazuyuki Fujita , and Yuichi ItohGraduate School of Science and Technology, Kwansei Gakuin University, Japan

School of Science and Technology, Kwansei Gakuin University, JapanGraduate School of Information Science and Technology, Osaka University, Japan

E-mail: bjf74781@kwansei.ac.jp

Abstract— We propose a portable umbrella-shaped device called U-brella as an application of “vibrationizing”information. Vibrationizing is a term coined to mean the transformation of various types of information into a vibration. Funbrella is an earlier version of U-brella that allows users to experience rain with vibrations, while U-brella offers them the ability to feel ultraviolet rays by converting them into vibration. We first conceptualized the implementation of U-brella: improving the mechanism of Funbrella’s vibration generator to make it lighter and easier to carry. Then we conducted a user study to confirm the efficiency of our system’s vibrationizing and users’ impressions of U-brella. The results showed that the participants easily perceived the amount of ultraviolet rays and that they really felt the rays pour down upon their heads with U-brella.

Keywords-virtual reality; ambient interface; haptic device; vibrationizing

I. INTRODUCTION

Mainly in the field of virtual reality, many studies have been done on haptic displays, which are becoming more fine-tunable. As a vibration display, “Funbrella” [3] generates the vibration of raindrops hitting an umbrella byrecoding and replaying actual rainfall data. Due to its mechanism, this device can represent various types of vibrations even if they have complex and irregular rhythm and strength. However, it cannot generate vibration unless someone records it in advance. If the device could represent intended vibration without recording, it would be a new type of haptic display that could intuitively convey the “pouring” information to a user. In addition, Funbrella cannot always be carried because the device requires a connection to an amplifier and PC.

Therefore, in this study, we propose the novel concept of “vibrationizing.” This means transforming various types of information into a vibration. We apply this concept to an ambient interface using a familiar tool in our daily life and propose an umbrella-shaped device called U-brella. U-brella changes ultraviolet rays into vibration. We focused on ultraviolet rays because they provide a type of information to be poured and, in practice, they require a warning be given to the user. U-brella was conceived to be used outside, but Funbrella could not be carried outside. Therefore, we

improved the mechanism of Funbrella to make it easy to carry. Moreover, we attached U-brella to a microcomputer and a UV-sensor, in addition to the vibration generator, in order to input and output the information of ultraviolet rays. In this paper, we propose the vibrationizing, implementation, and user feedback of U-brella.

II. U-BRELLA

A. Concepts In this study, we introduce “vibrationizing” as a means of

converting various kinds of information into vibration. Vibrationizing is expected to enable one to perceive information that is not even perceived by any of the five senses. In addition, we propose a portable umbrella-shaped device for vibrationizing information called U-brella. This device transforms ultraviolet rays’ information into vibration. The previous system (Funbrella) could not be carried because its control and vibration mechanisms were heavy. We improved the control and vibration systems of Funbrella to implement vibrationizing and make it portable. U-brella is conceived to be used outside, so it was necessary to improve the system architecture. Therefore, we design a simpler sensor, vibrator and control mechanism.

B. System architecture

IEEE Virtual Reality 201316 - 20 March, Orlando, FL, USA978-1-4673-4796-9/13/$31.00 ©2013 IEEE

Figure �. System flow of U-brella

ArduinoMusicShield

User

Ultraviolet rays

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UV-sensor

Op-amp

Li-ion Battery

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Amplifier

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Vibration

Figure 3. Control mechanism

amplifier

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MusicShield

Li-ion battery

Figure �. Vibration mechanism

Figure 4. Ultraviolet rays sensor

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4.0mm

An overview of U-brella is shown in Figure 1. We installed an ultraviolet sensor (UV-sensor) at the top of the umbrella and put a voice coil motor (VCM) under the UV-sensor to support the framework of the umbrella. VCM vibrates in response to the input level of the UV-sensor. The control mechanism is located near the handle of the umbrella. In the flow of its control, it first receives ultraviolet rays with a sensor and inputs them to the control mechanism. Hence information is input to the control mechanism from a sensor, and VCM vibrates based on this information. This system flow is shown in Figure �.

1) Control mechanism A large amplifier and PC were necessary for the

Funbrella system. Therefore, the control mechanism was changed from the PC to a microcomputer in U-brella, and the amplifier was changed to a small digital stereo amplifier (EK JAPAN Co., Ltd, PS-3246). This control mechanism is constructed using Arduino (Arduino Duemilanove 328), which is a microcomputer with MusicShield (galileo7 Co., Ltd, MusicShield) expanding it (Figure 3). The power supply is a Li-ion battery, which provides portability. The Li-ion battery is controlled by Arduino to prevent over-discharge. If the capacity of the Li-ion battery decreases, the LED lights warn the user.

2) Ultraviolet ray sensor In order to measure the ultraviolet ray information, an

ultraviolet ray sensor (Hamamatsu Photonics K. K., G5842UV) is attached to the top of the umbrella (Figure 4). The sensor is set into an object using ABS resin. The electric

current is output when this sensor receives ultraviolet rays; however, the sensor’s output is very weak. Therefore, the output is amplified by an operational amplifier (op-amp) and input to Arduino.

3) Vibration mechanism In the placement of the vibration mechanism, we decided

to set it in the upper part of the umbrella, as in the previous system. Thus, it conveys vibration to the shaft as a fulcrum while using the cloth of the umbrella as a speaker. In Funbrella, there is a certain distance between a magnet and a coil that creates vibration by the magnet’s attractive force and the repulsive force of the coil. However, it is not efficient because most of the magnetic field flows outside the magnet. Therefore, this mechanism uses VCM (BEI Kimco Magnetics, LA16-16-001A) for the structure of the magnetic closed circuit as a substitute for a magnet and a coil (Figure 5). Funbrella used wooden parts to support the magnet and coil, but we decided to changes the part to ABS resin to make it lighter. Funbrella uses three springs to realize attractive and repulsive force between a magnet and a coil, but U-brella is changed to be supported with eight springs (SR441HT, natural length 80 mm, outside diameter 8.9 mm, wire diameter 0.8 mm, stainless steel material) that are weaker than the previous parts. This is because the umbrella is supported by eight of these springs, which makes a stable framework. In addition, the mass of eight springs (16 g) is lighter than the mass of Funbrella’s three springs (48 g).

C. Vibration presentation technique Our technique is controlled to show rainy vibration,

depending on the amount of ultraviolet rays obtained from the sensor by Arduino. The amount of ultraviolet rays can be used to estimate the scale of the influence on a human body using an index called UV Index [1], which is defined by the Meteorological Agency. This index marks values as Low,

Figure 8. Questionnaire results

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5Agree

Disagree

Figure 7. Experimental setup Moderate, High, Very High and Extreme. U-brella shows vibration depending on the corresponding amount of ultraviolet rays. It is difficult to distinguish real rainy vibration from the rainy vibration created by the previous study [2], so the high and low values of the amount of ultraviolet rays are reached by increasing and decreasing the amplitude of the vibration.

As a preliminary experiment to determine the amplitude of the vibration depending on the amount of ultraviolet rays, we set U-brella in both the sun and shade to measure the amount of ultraviolet rays for one hour. According to the Meteorological Agency, the UV Index of the day was 3 at the experiment site.

D. Frequency characteristics We checked the rates of input and output voltage using

an oscilloscope to clarify the frequency characteristics of U-brella. Gain value is defined as follows:

Gain value = output voltage / input voltage (1)

The time of the greatest gain value is at resonance frequency, and gain value is checked at every frequency from 5 Hz to 1000 Hz (Figure 6). The results show that maximum gain value is approximately 160 to 180 Hz. As a result of our detailed investigations, we have found that maximum gain value is near 170 Hz.

From these findings, the resonance frequency of U-brella is around 170 Hz, and vibrations near this frequency are reproduced most efficiently. The skin of a person can sense vibration of around 300 Hz, but the gain value is approximately 10 at around 300 Hz in U-brella. Consequently, U-brella can produce a vibration in the frequency band that can be perceived by a person.

III. USER FEEDBACK

A. Overview The effectiveness of vibrationizing was investigated by

having a participant use U-brella in an experiment. The participant moves freely back and forth between the sun and the shade. The weather on the day of the experiment, at Kwansei Gakuin University’s Kobe-Sanda Campus, was sunny (ratio of clouds to clear sky: 40:60). Sixteen persons (14 males and 2 females) participated in the experiment. All participants were Japanese graduate or undergraduate

students whose ages ranged from 20 to 23 years (average: 22.0). The experimental setup is shown in Figure 7.

Participants answered a post-experiment questionnaire that asked the following six questions:

Q1. Did you feel that ultraviolet rays poured down? Q2. Did you feel that ultraviolet rays were avoided? Q3. Did you feel a difference in ultraviolet rays based

on High or Low values of the vibration? Q4. Did you feel comfortable to view ultraviolet rays by

vibration? Q5. Did you feel that showing the vibration served as a

warning? Q6. Did you feel pleasant as ultraviolet rays were

expressed in vibration? Participants answered these questions on a scale from 1

(disagree) to 5 (agree). In addition, they answered a question using a free-description form.

B. Results and discussions Figure 8 shows the resulting scores based on the

questionnaire’s five-point scale. Each bar indicates the average score of all participants’ rating responses. Each vertical line is shown standard deviation. These results show the usability and effectiveness of U-brella. First, Q1 to Q3 asked about the information presentation that can be provided by vibrationizing, and the responses marked high scores of around 4 or more. The results for Q1 show that participants felt ultraviolet rays were poured on them by vibrationizing. The results for Q2 show participants having the sense that ultraviolet rays were avoided by using the umbrella. According to the free-description form, they tried

Figure 6. Frequency characteristics

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to avoid ultraviolet rays because they felt them. For example, “I want to make an effort to avoid ultraviolet rays, because I recognize them from the vibration” and “I entered the shade consciously.” In addition, the results of Q3 show that participants can feel the high or low level of vibration due to the strength of ultraviolet rays. According to the free-description form, they felt high or low vibration because they said, “I felt the difference in the kind of vibration” and “I think that it is good, because it reacted just by entering the shade.”

Next, Q4 to Q6 are intended to confirm the impressions that participants received by vibrationizing. These questions also earned high scores of around 4. These results show that vibrationizing can give pleasure, warning and comfort to those receiving the vibration of the ultraviolet rays. Participants experienced not only the presentation of ultraviolet rays through vibration but also the various types of impressions made by vibrationizing. According to the free-description form, they enjoyed vibration while receiving a user warning; for instance, “I enjoyed the experience because the vibration was not just once.” Most comments related to the pleasure of having experienced vibrationizing.

Consequently, the results confirm the efficiency of vibrationizing using U-brella. Moreover, they show that U-brella can give information by vibrationizing that we would usually not be conscious of receiving.

IV. CONCLUSIONS We proposed “vibrationizing,” which means converting

various types of information into vibration in order to

intuitively convey information to a user. As an example of an application of vibrationizing, we implemented an umbrella-shaped device called U-brella by improving a previous system (Funbrella). U-brella gives the user information on ultraviolet rays through the vibration of raindrops. In addition, we succeeded in making the device portable by using a microcomputer and a small amplifier, while the previous system needs a complex setup. The user feedback showed that the participants experienced new feelings of the ultraviolet rays being actually poured.

Future work will need to give more consideration to saving weight. A method to move the control mechanism by using wireless communication from another place is being considered as a future method.

REFERENCES [1] http://www.jma.go.jp/en/uv/ [2] Fujii, Y., Kishino, F., Fujita, K., and Itoh Y. A study on

how to “vibrationize” information using Funbrella. VRSJ the 16th annual conference, pp. 296 -299, 2011(in Japanese).

[3] Fujita, K., Itoh, Y., Yoshida, A., Ozaki, M., Kikukawa, T., Fukazawa, R., Takashima, K., Kitamura, Y., and Kishino, F. Funbrella: Recording and Replaying Vibrations through an Umbrella Axis. In Proc of the International Conference on Advances in Computer Entertainment Technology (ACE2009), pp. 66 -71, 2009.