Publications

2025

1. 

   Adaptique: Multi-objective and Context-aware Online Adaptation of Selection Techniques in Virtual Reality

   Chao-Jung Lai, Mauricio Sousa, Tianyu Zhang, Ludwig Sidenmark, and Tovi Grossman

   In Proceedings of the 38th Annual ACM Symposium on User Interface Software and Technology (UIST ’25), 2025

   Abs Website

   Selection is a fundamental task that is challenging in virtual reality due to issues such as distant and small targets, occlusion, and target-dense environments. Previous research has tackled these challenges through various selection techniques, but complicates selection and can be seen as tedious outside of their designed use case. We present Adaptique, an adaptive model that infers and switches to the most optimal selection technique based on user and environmental information. Adaptique considers contextual information such as target size, distance, occlusion, and user posture combined with four objectives: speed, accuracy, comfort, and familiarity which are based on fundamental predictive models of human movement for technique selection. This enables Adaptique to select simple techniques when they are sufficiently efficient and more advanced techniques when necessary. We show that Adaptique is more preferred and performant than single techniques in a user study, and demonstrate Adaptique’s versatility in an application.

2023

1. 

   AirCharge: Amplifying Ungrounded Impact Force by Accumulating Air Propulsion Momentum

   Po-Yu Chen, Ching-Yi Tsai, Wei-Hsin Wang, Chao-Jung Lai, Chia-An Fan, Shih Chin Lin, Chia-Chen Chi, and Mike Y Chen

   In Proceedings of the 36th Annual ACM Symposium on User Interface Software and Technology, 2023

   Abs Website

   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.

2022

1. 

   Airracket: Perceptual design of ungrounded, directional force feedback to improve virtual racket sports experiences

   Ching-Yi Tsai, I-Lun Tsai, Chao-Jung Lai, Derrek Chow, Lauren Wei, Lung-Pan Cheng, and Mike Y Chen

   In Proceedings of the 2022 CHI Conference on Human Factors in Computing Systems, 2022

   Abs Website

   We present AirRacket, perceptual modeling and design of ungrounded, directional force feedback for virtual racket sports. Using compressed air propulsion jets to provide directional impact forces, we iteratively designed for three popular sports that span a wide range of force magnitudes: ping-pong, badminton, and tennis. To address the limited force magnitude of ungrounded force feedback technologies, we conducted a perception study which discovered the novel illusion that users perceive larger impact force magnitudes with longer impact duration, by an average factor of 2.57x. Through a series of formative, perceptual, and user experience studies with a combined total of 72 unique participants, we explored several perceptual designs using force magnitude scaling and duration scaling methods to expand the dynamic range of perceived force magnitude. Our user experience evaluation showed that perceptual designs can significantly improve realism and preference vs. physics-based designs for ungrounded force feed