We present a compact broadband linear actuator, Chasm, that renders expressive haptic feedback on wearable and handheld devices. Unlike typical motor-based haptic devices with integrated gearheads, Chasm utilizes a miniature leadscrew coupled to a motor shaft, thereby directly translating the high-speed rotation of the motor to the linear motion of a nut carriage without an additional transmission. Due to this simplicity, Chasm can render low-frequency skin-stretch and high-frequency vibrations, simultaneously and independently. We present the design of the actuator assembly and validate its electromechanical and perceptual performance. We then explore use cases and show design solutions for embedding Chasm in device prototypes. Finally, we report investigations with Chasm in two VR embodiments, i.e., in a headgear band to induce locomotion cues and in a handheld pointer to enhance dynamic manual interactions. Our explorations show wide use for Chasm in enhancing user interactions and experience in virtual and augmented settings.

Integration of soft haptic devices into garments can improve their usability and wearability for daily computing interactions. In this paper, we introduce PneuSleeve, a fabric-based, compact, and highly expressive forearm sleeve which can render a broad range of haptic stimuli including compression, skin stretch, and vibration. The haptic stimuli are generated by controlling pneumatic pressure inside embroidered stretchable tubes. The actuation configuration includes two compression actuators on the proximal and distal forearm, and four uniformly distributed linear actuators around and tangent to the forearm. Further, to ensure a suitable grip force, two soft mutual capacitance sensors are fabricated and integrated into the compression actuators, and a closed-loop force controller is implemented. We physically characterize the static and dynamic behavior of the actuators, as well as the performance of closed-loop control. We quantitatively evaluate the psychophysical characteristics of the six actuators in a set of user studies. Finally, we show the expressiveness of PneuSleeve by evaluating combined haptic stimuli using subjective assessments.

In this paper, we investigate the utility of remote tactile feedback for freehand text-entry on a mid-air Qwerty keyboard in VR. To that end, we use insights from prior work to design a virtual keyboard along with different forms of tactile feedback, both spatial and non-spatial, for fingers and for wrists. We report on a multi-session text-entry study with 24 participants where we investigated four vibrotactile feedback conditions: on-fingers, on-wrist spatialized, on-wrist non-spatialized, and audio-visual only. We use micro-metrics analyses and participant interviews to analyze the mechanisms underpinning the observed performance and user experience. The results show comparable performance across feedback types. However, participants overwhelmingly prefer the tactile feedback conditions and rate on-fingers feedback as significantly lower in mental demand, frustration, and effort. Results also show that spatialization of vibrotactile feedback on the wrist as a way to provide finger-specific feedback is comparable in performance and preference to a single vibration location. The micro-metrics analyses suggest that users compensated for the lack of tactile feedback with higher visual and cognitive attention, which ensured similar performance but higher user effort.

In virtual reality, the lack of kinesthetic feedback often prevents users from experiencing the weight of virtual objects. Control-to-display (C/D) ratio manipulation has been proposed as a method to induce weight perception without kinesthetic feedback. Based on the fact that lighter (heavier) objects are easier (harder) to move, this method induces an illusory perception of weight by manipulating the rendered position of users' hands---increasing or decreasing their displayed movements. In a series of experiments we demonstrate that C/D-ratio induces a genuine perception of weight, while preserving ownership over the virtual hand. This means that such a manipulation can be easily introduced in current VR experiences without disrupting the sense of presence. We discuss these findings in terms of estimation of physical work needed to lift an object. Our findings provide the first quantification of the range of C/D-ratio that can be used to simulate weight in virtual reality.