CHI ’25, Yokohama, Japan

In this paper, we present an adaptive walker system designed to address limitations in current intelligent walker technologies. While recent advancements have been made in this field, existing systems often struggle to seamlessly interpret user intent for speed control and lack adaptability across diverse scenarios and terrain. Our proposed solution incorporates high-resolution tactile sensors, deep learning algorithms, IMU sensors, and linear motors to dynamically adjust to the user's intentions and terrain changes. The system is capable of predicting the user's desired speed with an error margin of only 20.99%, relying solely on tactile input from hand and arm contact points. Additionally, it maintains the walker's horizontal stability with an error of less than 1 degree by adjusting leg lengths in response to variations in ground angle. This adaptive walker enhances user safety and comfort, particularly for individuals with reduced strength or cognitive abilities, and offers reliable assistance on uneven terrain such as uphill and downhill paths.

Passengers can engage more in nondriving-related tasks owing to recent advancements in autonomous vehicles (AVs), making immersive tools such as virtual reality (VR) appealing; however, motion sickness (MS) remains a significant challenge. We present SYNC-VR, a system that aligns with visual, haptic, and auditory cues and provides proprioceptive feedback to illustrate its effect on MS and presence within the in-vehicle VR. We conducted an experiment with 24 participants using a real vehicle along a route with known MS-triggering events. Using subjective and physiological measures, we assessed participants’ presence and MS under four conditions by gradually varying the level of synchronized input sensations. Results reveal that SYNC-VR reduces MS and increases the sense of presence. Additionally, it emphasizes the impact of our interactive VR content and its role in achieving proprioceptive feedback with haptic feedback through electrical muscle stimulation, introducing an innovative approach to MS mitigation in in-vehicle VR.

This study presents ErgoPulse, a system that integrates biomechanical simulation with electrical muscle stimulation (EMS) to provide kinesthetic force feedback to the lower-body in virtual reality (VR). ErgoPulse features two main parts: a biomechanical simulation part that calculates the lower-body joint torques to replicate forces from VR environments, and an EMS part that translates torques into muscle stimulations. In the first experiment, we assessed users’ ability to discern haptic force intensity and direction, and observed variations in perceived resolution based on force direction. The second experiment evaluated ErgoPulse’s ability to increase haptic force accuracy and user presence in both continuous and impulse force VR game environments. The experimental results showed that ErgoPulse’s biomechanical simulation increased the accuracy of force delivery compared to traditional EMS, enhancing the overall user presence. Furthermore, the interviews proposed improvements to the haptic experience by integrating additional stimuli such as temperature, skin stretch, and impact.

This study introduces "Flip-Pelt," a motor-driven peltier device designed to provide rapid thermal stimulation and congruent pressure feedback in virtual reality (VR) environments. Our system incorporates eight motor-driven peltier elements, allowing for the flipping of preheated or cooled elements to the opposite side. In evaluating the Flip-Pelt device, we assess user ability to distinguish between heat/cold sources by their patterns and stiffness, and its impact on enhancing haptic experiences in VR content that involves contact with various thermal sources. Our findings demonstrate that rapid thermal stimulation and congruent pressure feedback provided by Flip-Pelt enhance the recognition accuracy of thermal patterns and the stiffness of virtual objects. These features also improve haptic experiences in VR scenarios through their temporal congruency between tactile and thermal stimuli. Additionally, we discuss the scalability of the Flip-Pelt system to other body parts by proposing design prototypes.

With the introduction of autonomous vehicles, pedestrians may no longer expect explicit communication from drivers. Despite the anticipated safety benefits of anthropomorphic human–machine interfaces (HMIs) for pedestrian crossings, the impact of different levels of anthropomorphism and communication on pedestrian safety remains insufficiently understood. We proposed a virtual-agent (VA) HMI that mimics driver behavior and investigated pedestrians’ preferences through augmented reality (AR) experiments. Eighteen participants made decisions about crossing after receiving cues about the vehicle’s intentions from VA HMIs. Participants preferred the "characterized" VA HMI owing to its aesthetically pleasing design and found the "eye contact + hand gesture" combination to be more easily comprehensible. We found that while the degree of anthropomorphism did not significantly affect pedestrians’ crossing decisions, more explicit communication was helpful. Our study provides empirical evidence regarding users’ experiences of HMI in AR and the effectiveness of VA HMIs that imitate driver communication modes.

Redirected walking (RDW) is a technology that enables users to walk seamlessly in an enormous virtual space within a narrow real space while avoiding collisions with physical elements. Although RDW provides accurate proprioceptive sensations, redirection performance is limited by visual–vestibular inconsistencies. This study aims to support seamless walking in a VR environment by alleviating inconsistencies using four vestibular stimulations: noisy and directional galvanic vestibular stimulation, bone-conduction vibration, and caloric vestibular stimulation. The user study demonstrated that the stimulations successfully enable spatial expansion without impairing immersion and presence. Non-electrical stimulations (bone-conduction vibration and caloric vestibular stimulation) expanded the detection threshold, making them alternatives to electrical stimulations, and direction-based stimulation (directional galvanic vestibular stimulation) improved the user’s gait stability in RDW. Finally, the findings suggested improving the user experience for vestibular stimulation RDW either by lowering audio interference or increasing the synchronization between the RDW gain and the stimulation intensity.

This study explored bone-conduction vibration (BCV) in redirected walking (RDW), a technology for seamless walking in large virtual spaces within confined physical areas, enhancing obstacle avoidance performance using nonelectrical vestibular stimulation without the side effects caused by electrical stimulation. We proposed four different BCV stimulation methods and evaluated their detection threshold (DT) extension performance and user experience in virtual reality (VR) conditions. The DT was successfully expanded from at least 23% to 45% under all BCV conditions while preserving the immersion and presence. Notably, user comfort increased when content sound was used for vestibular stimulation. Under the extended DT condition, a simulation study demonstrated that all BCV stimulation methods facilitated uninterrupted walking over extended distances when applying RDW to users with random movements. Thus, this research established the viability of using BCV in RDW applications and the potential for incorporating content sound into BCV stimulation techniques.