Wearable Haptic Display to present Virtual Mass Sensation
Kouta Minamizawa*1
The University of Tokyo

Souichiro Fukamachi*2
The University of Tokyo

Naoki Kawakami*4
The University of Tokyo

Hiroyuki Kajimoto*3
The University of Electro-Communications
Susumu Tachi*5
The University of Tokyo

We propose a wearable haptic display to present the weight
sensation of a virtual object, which is based on our novel insightthat the deformation on fingerpads makes a reliable weight
sensation even when the proprioceptive sensation is absent. Thisdevice will provide a new form of ubiquitous haptic interaction.

1. Introduction
In recent times, there have been a number of computer userinterface devices that have some haptic feedback functions, suchas the DUALSHOCK controller [Sony Computer Entertainment,Inc. 1997] or the Wii Remote [Nintendo Co., Ltd. 2006]. However,their haptic feedback is limited to only the vibration function since
there is no other method to provide haptic feedback that can be
implemented with a small and inexpensive device. On the otherhand, there is an increasing demand for realistic haptic feedback;thus, a simple and inexpensive method for a highly realistic haptic
display is required. To meet this requirement, we propose awearable haptic display to present the mass of a virtual object asshown in Figure 1. We focused on the mass of a virtual object,which contributes to the weight and the inertia mass in hapticinteraction. If the virtual mass is presented by a haptic device, theuser can perceive a more realistic sensation of the virtual object
by grasping than the vibration feedback.

2. Principle
In our previous researches [Minamizawa et al., 2007], weinvestigated the possibility of realizing a simple haptic display on
the basis of finger deformation. Conventionally, it is believed that
it is necessary to reproduce the proprioceptive sensation in orderto present a weight sensation and thus a large grounded device isrequired. However, we found that the deformation of thefingerpads due to the weight of an object can generate a reliableweight sensation even when the proprioceptive sensations on thewrist and arm are absent. Based on this observation, we designed
the mechanism of the haptic display as shown in Figure 2, which
has a simple structure comprising dual motors.

Real world

Virtual worldFigure 1: Conceptual representation of our proposed device.
By wearing our proposed devices on the index finger and thethumb, the user can feel the augmented weight and inertia of
the water that is virtually filled in the actually empty glass.

Figure 2: Our proposed method for generating
vertical stress (left) and shearing stress (right).

Figure 3: Implemented prototype device.

3. Prototype Device

4. Conclusion

We implemented the prototype device shown in Figure 3 and thenconfirmed the recognition ability of the weight sensation
presented on the user’s finger by this method. By wearing ourproposed devices on the index finger and the thumb, the user canperceive the grip force and the mass of a virtual object. The grip
force, gravity, and inertia mass of a virtual object are presented on
the user’s fingerpads during shaking and rotational motion.

We found that the vertical and sharing stresses on the fingerpads
due to the weight of the object can generate a reliable weight
sensation even when the proprioceptive sensation on the wrist orarm is absent. On the basis of this observation, we designed awearable ungrounded haptic display to present the gravity
sensation of a virtual object using dual motors and a belt. Thismethod is simple and it can be introduced in daily-life. We thenimplemented the prototype devices and confirmed that virtual
mass sensations can be presented.

*1

e-mail: kouta_minamizawa@ipc.i.u-tokyo.ac.jp
e-mail: souichiro_fukamachi@ipc.i.u-tokyo.ac.jp*3e-mail: kajimoto@hc.uec.ac.jp*4e-mail: kawakami@star.t.u-tokyo.ac.jp*5e-mail: tachi@star.t.u-tokyo.ac.jp*2

MINAMIZAWA, K., KAJIMOTO, H., KAWAKAMI, N. AND TACHI, S. 2007.
Wearable Haptic Display to Present Gravity Sensation – Preliminary
Observations and Device Design, In Proceedings of World Haptics
2007, Tsukuba, Tokyo, 133-138