Impact events, which generate directional forces with extremely short impulse durations and large force magnitudes, are prevalent in both virtual reality (VR) games and real-world experiences. However, despite recent advancement in ungrounded force feedback technologies, such as air jet propulsion and propellers, these technologies remain 5-100x weaker and 10-500x slower compared to real-world impact events. For instance, they can only achieve 4𝑁 with a minimal duration of 50-500𝑚𝑠 compared to the 20-400𝑁 forces generated within 1-5𝑚𝑠 for baseball, ping-pong, drumming, and tennis. To overcome these limitations, we present AirCharge, a novel haptic device that accumulates air propulsion momentum to generate instantaneous, directional impact forces. By mounting compressed air jets on rotating swingarms, AirCharge can amplify impact force magnitude by more than 10x while matching real-world impulse duration of 3𝑚𝑠. To support high-frequency impacts, we explored and evaluated a series of device designs, culminating in a novel reciprocating dual-swingarm design that leverages a reversing bevel gearbox to eliminate gyro effects and to achieve impact feedback of up to 10𝐻𝑧. User experience evaluation (n = 16) showed that AirCharge significantly enhanced realism and is preferred by participants compared to air jets without the charging mechanism.
Virtual and augmented reality headsets are making significant progress in audio-visual immersion and consumer adoption. However, their haptic immersion remains low, due in part to the limitations of vibrotactile actuators which dominate the AR/VR market. In this work, we present a new approach to create high-resolution shape-changing fingerpad arrays with 20 haptic pixels/cm\textsuperscript{2}. Unlike prior pneumatic approaches, our actuators are low-profile (5mm thick), low-power (approximately 10mW/pixel), and entirely self-contained, with no tubing or wires running to external infrastructure. We show how multiple actuator arrays can be built into a five-finger, 160-actuator haptic glove that is untethered, lightweight (207g, including all drive electronics and battery), and has the potential to reach consumer price points at volume production. We describe the results from a technical performance evaluation and a suite of eight user studies, quantifying the diverse capabilities of our system. This includes recognition of object properties such as complex contact geometry, texture, and compliance, as well as expressive spatiotemporal effects.
https://doi.org/10.1145/3586183.3606771
For grasping, tactile stimuli to multiple fingertips are crucial for realistic shape rendering and precise manipulation. Pinching is particularly important in virtual reality since it is frequently used to grasp virtual objects. However, the interaction space of tactile feedback around pinching is underexplored due to a lack of means to provide co-located but different stimulation to finger pads. We propose a double-sided electrotactile device with a thin and flexible form factor to fit within pinched fingerpads, comprising two overlapping 3 × 3 electrode arrays. Using this new tactile interface, we define a new concept of double-sided tactile interactions with three feedback modes: (1) single-sided stimulation, (2) simultaneous double-sided stimulation, and (3) spatiotemporal double-sided stimulation. Through two user studies, we (1) demonstrate that participants can accurately discriminate between single-sided and double-sided stimulation and find a qualitative difference in tactile sensation; and (2) confirm the occurrence of apparent tactile motion between fingers and present optimal parameters for continuous or discrete movements. Based on these findings, we demonstrate five VR applications to exemplify how double-sided tactile interactions can produce spatiotemporal movement of a virtual object between fingers and enrich touch feedback for UI operation.
Haptic interfaces have been extended to the feet to enhance foot-based activities, such as guidance while walking or stepping on virtual textures. Most feet haptics use mechanical actuators, namely vibration motors. However, we argue that vibration motors are not the ideal actuators for all feet haptics. Instead, we demonstrate that electrotactile stimulation provides qualities that make it a powerful feet-haptic interface: (1) Users wearing electrotactile can not only feel the stimulation but can also better feel the terrain under their feet—this is critical as our feet are also responsible for the balance on uneven terrains and stairs—electrotactile achieves this improved “feel-through” effect because it is thinner than vibrotactile actuators, at 0.1 mm in our prototype; (2) While a single vibrotactile actuator will also vibrate surrounding skin areas, we found improved two-point discrimination thresholds for electrotactile; (3) Electrotactile can be applied directly to soles, insoles or socks, enabling new applications such as barefoot interactive experiences or without requiring users to have custom-shoes with built-in vibration motors. Finally, we demonstrate applications in which electrotactile feet interfaces allow users to feel not only virtual information but also the real terrain under their shoes, such as a VR experience where users walk on ground props and a tactile navigation system that augments the ground with virtual tactile paving to assist pedestrians in low-vision situations.
https://doi.org/10.1145/3586183.3606808
Rendering haptic feedback for interactions with virtual objects is an essential part of effective virtual reality experiences. In this work, we explore providing haptic feedback for rotational manipulations, e.g., through knobs. We propose the use of a Pseudo-Haptic technique alongside a physical proxy knob to simulate various physical resistances. In a psychophysical experiment with 20 participants, we found that designers can introduce unnoticeable offsets between real and virtual rotations of the knob, and we report the corresponding detection thresholds. Based on these, we present the Pseudo-Haptic Resistance technique to convey physical resistance while applying only unnoticeable pseudo-haptic manipulation. Additionally, we provide a first model of how C/D gains correspond to physical resistance perceived during object rotation, and outline how our results can be translated to other rotational manipulations. Finally, we present two example use cases that demonstrate the versatility and power of our approach.
https://doi.org/10.1145/3586183.3606787
Utilizing everyday objects as tangible proxies for Augmented Reality (AR) provides users with haptic feedback while interacting with virtual objects. Yet, existing methods focus on the attributes of the objects, constraining the possible proxies and yielding inconsistency in user experience. Therefore, we propose Ubi-TOUCH, an AR system that assists users in seeking a wider range of tangible proxies for AR applications based on the hand-object interaction (HOI) they desire. Given the target interaction with a virtual object, the system scans the users' vicinity and recommends object proxies with similar interactions. Upon user selection, the system simultaneously tracks and maps users' physical HOI to the virtual HOI, adaptively optimizing object 6 DoF and the hand gesture to provide consistency between the interactions. We showcase promising use cases of Ubi-TOUCH, such as remote tutorials, AR gaming, and Smart Home control. Finally, we evaluate the performance and usability of Ubi-TOUCH with a user study.
https://doi.org/10.1145/3586183.3606793