Design, Control, and Psychophysics of Tasbi: A Force-Controlled Multimodal Haptic Bracelet

Abstract

Haptic feedback is known to enhance the realism of an individual’s interactions with objects in virtual environments. Wearable haptic devices, such as vibrotactile sleeves or armbands, can provide haptic feedback in a smaller and more lightweight form factor than haptic gloves that can be bulky and cumbersome to the wearer. In this article, we present tactile and squeeze bracelet interface (Tasbi), a multimodal haptic wristband that can provide radial squeeze forces around the wrist along with vibrotactile feedback at six discrete locations around the band. Tasbi implements a squeezing mechanism that minimizes tangential forces between the band’s points of contact with the skin, instead of focusing the motor actuation to predominantly normal forces. Force sensing capacitors enable closed-loop control of the squeeze force, while vibration is achieved with linear resonant actuators. A detailed description of the design and experimental results demonstrating closed-loop control of squeeze cues provided by Tasbi is presented. Additionally, we present the results of psychophysical experiments that quantify user perception of the vibration and squeeze cues, including vibrotactile identification accuracy in the presence of varying squeeze forces, discrimination thresholds for the squeeze force, and an analysis of user preferences for squeeze actuation magnitudes.