Tactile Ring: Multi-Mode Finger-Worn Soft Actuator for Rich Haptic Feedback

Abstract

This paper presents a novel finger-worn actuator capable of generating three distinctive haptic effects: static pressure, high-frequency vibration, and an impact. Our new design makes this multi-mode feedback with a single actuator possible in a small form factor. A ring-shaped air bladder made with soft silicone is inflated or deflated to generate feedback on the finger. The airflow is controlled by a pair of air valves connected to a compressed air tank. Besides static pressure, the actuator can generate high-frequency vibration with high acceleration and crisp impact feedback due to fast controllability of the valves with a strong air source and a lightweight bladder membrane. In addition, our special design and fabrication of the bladder-a combination of stretchable and non-stretchable membrane layers in the ring-allows for stronger feedback. Rendering algorithms for three kinds of feedback are also presented. The performance of the system and the characteristics of the feedback are thoroughly examined using a series of measurement experiments, revealing that the system can generate a static force up to 6.3 N, the vibration up to 2.2 g magnitude and 250 Hz frequency, and an impact with less than 5 ms of latency. The whole system weighs only 255 grams (4.5 grams for the actuator and 250 grams for the controller). Finally, we demonstrate the wearability of the system by integrating the modules into a self-contained haptic device in the form of a wristlet.

Towards high performance and durable soft tactile actuators

“…This is accomplished by controlling pressure sequences, adjusting inflation and deflation durations, and varying pressure amplitudes. 156 By adopting this strategy, a ring-shaped SPA was designed to deliver multi-mode tactile feedback, encompassing static pressure, impact, and vibrational sensations to the user finger (Fig. 6a).…”

“…6a). 156 Static pressure generation depended on the positive pressure valve opening duration. On the other hand, impact feedback is achieved by inflating the chamber, followed by a sequence involving the immediate closing and opening of positive and negative pressure valves, respectively.…”

Soft Pneumatic Fingertip Actuator Incorporating a Dual Air Chamber to Generate Multi-Mode Simultaneous Tactile Feedback

“…The device was capable of rendering the realistic hardness and softness of soft surfaces. Talhan et al [9] proposed a pneumatic ring-shaped finger-worn actuator that provided multi-mode haptic feedback consecutively in a VR or AR environment. They utilized a single air chamber between the stretchable and non-stretchable membrane to render haptic feedback.…”

“…A multi-mode haptic actuator can be a solution to overcome the aforementioned issue. It has already been proven that a pneumatically controlled soft actuator can provide high-frequency vibrotactile feedback and pressure feedback with a single actuator [9]. Furthermore, it offers various functional advantages, which include lightweightness, flexibility, high strain density, and ease of fabrication as per the desired shape [10,11].…”

On the perceived realism of virtual textures rendered by a vibrotactile wearable ring display

“…While the aforementioned works repeatedly demonstrate that people can identify distinct vibration patterns as different textures and are sensitive to changes in frequency, intensity, and spectral complexity, preliminary research [18] is still exploring whether such rich frequency information even remains intelligible when relocated away from the fingertip. Other research groups are focusing primarily on device design of low-profile wearable texture displays, demonstrating compact methods of actuation, broadband vibratory feedback, and responsiveness to hand tracking [19], [20].…”