Wearable Vibrotactile Haptic Device for Stiffness Discrimination during Virtual Interactions

Abstract

In this paper, we discuss the development of cost effective, wireless, and wearable vibrotactile haptic device for stiffness perception during an interaction with virtual objects. Our experimental setup consists of haptic device with five vibrotactile actuators, virtual reality environment tailored in Unity 3D integrating the Oculus Rift Head Mounted Display (HMD) and the Leap Motion controller. The virtual environment is able to capture touch inputs from users. Interaction forces are then rendered at 500 Hz and fed back to the wearable setup stimulating fingertips with ERM vibrotactile actuators. Amplitude and frequency of vibrations are modulated proportionally to the interaction force to simulate the stiffness of a virtual object. A quantitative and qualitative study is done to compare the discrimination of stiffness on virtual linear spring in three sensory modalities: visual only feedback, tactile only feedback, and their combination. A common psychophysics method called the Two Alternative Forced Choice (2AFC) approach is used for quantitative analysis using Just Noticeable Difference (JND) and Weber Fractions (WF). According to the psychometric experiment result, average Weber fraction values of 0.39 for visual only feedback was improved to 0.25 by adding the tactile feedback.

Design of a Wearable Fingertip Haptic Device for Remote Palpation: Characterisation and Interface with a Virtual Environment

“…This differs from other works in the literature, where, for example, stiffness is modelled as a rigid spring (Maereg et al, 2017). Furthermore, the FHD can allow for both "pressing" and "tapping" on the user's fingertip, depending on the task, unlike haptic devices mentioned in the Introduction Section which are continuously in contact with the user's fingertip.…”

“…Some exoskeleton designs are bulky while some cover just fingertips, which can be especially effective for tactile applications and controllable cutaneous feedback (Pacchierotti et al, 2017) and can be classified according to the cutaneous sensation that they provide: normal indentation, tangential motion, lateral skin stretch or vibration (Pacchierotti et al, 2017). An example of use of vibration for haptic feedback is the device by Maereg et al (2017) with five vibro-tactile actuators, one for each fingertip of the user. Although wearable devices usually provide cutaneous stimuli, with most of the kinaesthetic feedback missing (Prattichizzo et al, 2013), it is possible to compensate for this deficiency without significant performance degradation (Pacchierotti et al, 2014).…”

“…Motors actuate three legs connecting these two parts to render forces from the virtual environment. A virtual environment is used for testing also in the work by Maereg et al (2017) where tracking is done via a LeapMotion controller and PHF is also explored by visualising displacement in the virtual environment.…”

SwarmTouch: Guiding a Swarm of Micro-Quadrotors With Impedance Control Using a Wearable Tactile Interface

“…force vector, vibration, and contact state [19]. However, vibration motors, which are easy to control, are widely applied in Virtual Reality [20], [21]. We applied eccentric rotating mass (ERM) vibration motors which deliver the dynamic state of the swarm in the form of tactile patterns.…”

Empowering Persons with Deafblindness

“…• Vibrotactile feedback uses vibration motors to provide feedback: its most familiar uses are "rumbles" in videogames or alerts on smartphones, but it can also be used in quite nuanced ways, such as the display of variable stiffness through different vibration intensities [22]. Such uses can well be adapted for communication purposes of deafblind persons.…”