arXiv subjects

Tatsuki Fushimi

Publications and source records attributed to Tatsuki Fushimi.

18 recordsLinked to original sources

arXiv2026

Event-Based Spatial-Carrier Interferometry for Surface-Normal Vibration-Waveform Reconstruction

Non-contact measurement of small vibrations perpendicular to a surface supports the evaluation of mechanical structures, but in camera-based interferometry, increasing the frame rate makes a trade-off with the field of view and spatial resolution. By recording only brightness changes, event cameras avoid this trade-off and reach high temporal and spatial resolution; our previously reported event topology-based visual vibrometer recovers vibration from apparent motion. This high-speed, high-resolution sensing is well suited to full-field measurement, yet such vibration produces too little apparent motion to capture its waveform. Here we show that event-based spatial-carrier interferometry reconstructs that waveform from moving interference fringes. That displacement moves the fringes, and signed event-density maps built from the event stream are demodulated at the spatial carrier to recover the interferometric phase and fix the otherwise ambiguous motion direction at turning points. Reconstructed waveforms agree with laser Doppler vibrometry over broad drive-frequency and amplitude ranges, with limits set by the maximum fringe speed and the sensor performance. Reconstruction is limited by a minimum aperture of about two fringe periods along the carrier and one along the fringes, which allows the surface to be mapped region by region. These results provide an empirical basis for full-field, spatially resolved interferometric vibrometry with event cameras as a non-contact measurement technique.

physics.app-ph↗

arXiv2026

Galvanic Vestibular Stimulation in Latent Space

Galvanic vestibular stimulation (GVS) is widely used to modulate self-orientation, balance, and motion perception; the discriminability of frequency-encoded cues further suggests its potential as a standalone modality for embodied feedback. However, synthesizing GVS waveforms congruent with target events or bodily states remains challenging. GVS waveforms combine current direction, intensity, duration, and onset and offset transitions, yet how these parameters jointly shape users' perceptual and associative responses remains underexplored. To address this gap, we contribute a dataset linking GVS waveforms to free-form experience descriptions, as well as a retrieval-guided generative model for synthesizing candidate waveforms from target descriptions. The dataset comprises 100 GVS waveforms and 1,526 valid free-form sensation descriptions collected from 16 participants. Semantic analysis revealed diverse motion- and force-related sensations, localized bodily sensations, and situational associations. Compared with a participant-preserving permutation baseline, descriptions elicited by the same waveform covered fewer semantic categories (8.18 vs. 9.45) and exhibited a higher dominant-category proportion (26.97% vs. 21.25%; both P < 0.001). Building on this dataset, we implemented the generative model as a retrieval-guided one-dimensional convolutional variational autoencoder. An independent behavioral study recruited 10 participants who had not contributed to the dataset collection. Performance in discriminating congruent from incongruent waveform-visual cue pairings was significantly above chance, with an accuracy of 63.33%, d-prime = 0.70, and p < 0.001. Together, these findings demonstrate the feasibility of text-conditioned GVS synthesis and support the development of GVS as a programmable modality for semantically congruent embodied feedback across interactive scenarios.

cs.HC↗

arXiv2026

WhiteTesseract: Reframing the Interpretation of Cultural Heritage through XR and Conversational AI

Cultural heritage exhibitions often struggle to sustain attention and support reflective engagement. Physical exhibitions rely on fixed interpretive aids that lack adaptability to individual backgrounds or curiosity, and their effectiveness depends heavily on a visitor's Personal Context, prior knowledge, and cultural literacy. Meanwhile, digital exhibitions prioritize convenience and accessibility but risk weakening the Physical and Social Contexts that define embodied cultural experience. WhiteTesseract addresses this gap by enabling in-situ interpretation through high-resolution XR and conversational AI. The system integrates spatial intelligence via artwork recognition to allow visitors to selectively reduce environmental distractions (via diminished reality) and engage in context-aware dialogue (via large language models). The goal is to preserve the richness of the physical and social environment while providing a flexible space for personal reflection, enhancing Personal Context without compromising physical authenticity. We deployed the system in a Claude Monet exhibition and conducted a controlled user study with 26 participants. Quantitative results showed that WhiteTesseract modulation significantly increased average viewing duration from 35.3 to 98.3 seconds (p < 0.001). Analysis of 529 visitor-AI interactions revealed that 60% extended beyond factual queries to include analytical, emotional, and comparative inquiries. These findings demonstrate how XR and AI can enrich the physical exhibition experience by supporting deeper, more personalized engagement without displacing the embodied value of cultural heritage. We discuss technical and social constraints for real-world deployment and limitations of our controlled setting.

cs.HC↗

arXiv2026

Acoustic Manipulation of Tangible Janus Icons on Liquid Droplets

Interfaces that couple digital information with physical matter enable computation to be expressed through tangible motion and touch, yet typically rely on embedded actuators, rigid mechanisms, or enclosed environments. Consequently, contactless manipulation and interaction with centimeter-scale tangible elements in open settings remain difficult to achieve. Here, we present PolygonWave, a solid--fluid acoustic interface that enables transport and tangible interaction by coupling airborne ultrasound with liquid-mediated support. The system employs lightweight Janus icons with asymmetric wettability: a superhydrophobic upper surface permits dry touch interaction, while a hydrophilic lower surface couples to a water droplet resting on a superhydrophobic mesh. Focused acoustic fields generated by a 256-element phased array induce lateral forces, enabling programmable motion without mechanical contact. Systematic characterization demonstrates transport of payloads up to 525 mg across variations in icon size, droplet volume, and applied load. Beyond translation, the liquid layer functions as a reconfigurable mechanical element, enabling button-like input with self-recovery and resonance-driven vibro-visual feedback, exhibiting a peak response near 22 Hz for 200 \textmu L droplets. Liquid-mediated acoustic coupling provides a unified mechanism for mechanically expressive, touch-accessible tangible interfaces bridging acoustics, soft matter physics, and physical human--computer interaction.

physics.app-ph↗

arXiv2026

Reversible vertical positioning of acoustically levitated particle using a spiral reflector

Dynamic positioning in acoustic levitation typically depends on active control of the transducers phases, which necessitates complex driving electronics. While mechanically actuated reflectors offer a simpler alternative, achieving reversible transport along the vertical axis solely through mechanical actuation remains challenging. Here, we demonstrate vertical particle translation using a rotating spiral reflector with a half-wavelength pitch. With the rotation axis laterally offset relative to the acoustic focus, the spiral surface functions as a series of translating slopes. Experimental and numerical results confirm stable, bidirectional transport, yielding a vertical displacement of approximately $0.58\lambda$ per revolution and a maximum height of $3.18\lambda$, with radial confinement maintained within $0.24\lambda$. This approach provides a cost-effective solution for non-contact sample handling without active phase control.

physics.app-ph↗

arXiv2025

Event Topology-based Visual Microphone for Amplitude and Frequency Reconstruction

Accurate vibration measurement is vital for analyzing dynamic systems across science and engineering, yet noncontact methods often balance precision against practicality. Event cameras offer high-speed, low-light sensing, but existing approaches fail to recover vibration amplitude and frequency with sufficient accuracy. We present an event topology-based visual microphone that reconstructs vibrations directly from raw event streams without external illumination. By integrating the Mapper algorithm from topological data analysis with hierarchical density-based clustering, our framework captures the intrinsic structure of event data to recover both amplitude and frequency with high fidelity. Experiments demonstrate substantial improvements over prior methods and enable simultaneous recovery of multiple sound sources from a single event stream, advancing the frontier of passive, illumination-free vibration sensing.

physics.app-ph↗

arXiv2025

Dynamic Caustics by Ultrasonically Modulated Liquid Surface

This paper presents a method for generating dynamic caustic patterns by utilising dual-optimised holographic fields with Phased Array Transducer (PAT). Building on previous research in static caustic optimisation and ultrasonic manipulation, this approach employs computational techniques to dynamically shape fluid surfaces, thereby creating controllable and real-time caustic images. The system employs a Digital Twin framework, which enables iterative feedback and refinement, thereby improving the accuracy and quality of the caustic patterns produced. This paper extends the foundational work in caustic generation by integrating liquid surfaces as refractive media. This concept has previously been explored in simulations but not fully realised in practical applications. The utilisation of ultrasound to directly manipulate these surfaces enables the generation of dynamic caustics with a high degree of flexibility. The Digital Twin approach further enhances this process by allowing for precise adjustments and optimisation based on real-time feedback. Experimental results demonstrate the technique's capacity to generate continuous animations and complex caustic patterns at high frequencies. Although there are limitations in contrast and resolution compared to solid-surface methods, this approach offers advantages in terms of real-time adaptability and scalability. This technique has the potential to be applied in a number of areas, including interactive displays, artistic installations and educational tools. This research builds upon the work of previous researchers in the fields of caustics optimisation, ultrasonic manipulation, and computational displays. Future research will concentrate on enhancing the resolution and intricacy of the generated patterns.

cs.GR↗

arXiv2025

From Geometry to Culture: An Iterative VLM Layout Framework for Placing Objects in Complex 3D Scene Contexts

3D layout tasks have traditionally concentrated on geometric constraints, but many practical applications demand richer contextual understanding that spans social interactions, cultural traditions, and usage conventions. Existing methods often rely on rule-based heuristics or narrowly trained learning models, making them difficult to generalize and frequently prone to orientation errors that break realism. To address these challenges, we define four escalating context levels, ranging from straightforward physical placement to complex cultural requirements such as religious customs and advanced social norms. We then propose a Vision-Language Model-based pipeline that inserts minimal visual cues for orientation guidance and employs iterative feedback to pinpoint, diagnose, and correct unnatural placements in an automated fashion. Each adjustment is revisited through the system's verification process until it achieves a coherent result, thereby eliminating the need for extensive user oversight or manual parameter tuning. Our experiments across these four context levels reveal marked improvements in rotation accuracy, distance control, and overall layout plausibility compared with native VLM. By reducing the dependence on pre-programmed constraints or prohibitively large training sets, our method enables fully automated scene composition for both everyday scenarios and specialized cultural tasks, moving toward a universally adaptable framework for 3D arrangement.

cs.GR↗

arXiv2025

Experimental and Numerical Study of Acoustic Streaming in Mid-Air Phased Arrays

Mid-air acoustic streaming, where ultrasound induces steady fluid motion, could significantly affect the perception of haptic sensations, stability of levitation systems, and enable controlled transfer of odours (smells) through air by directing volatile compounds to specific locations. Despite its importance, the streaming behavior in airborne phased-array transducers remains poorly understood. Here, we use particle image velocimetry and numerical simulations to investigate streaming dynamics in single- and multi-focus acoustic fields. Experimental measurements reveal streaming velocities exceeding $0.4~\text{m/s}$ in single-focus configurations and up to $0.3~\text{m/s}$ in multi-focus setups, with distinct grating lobe-induced lateral jets. While multi-physics finite-element models effectively capture central streaming, they exhibit subtle differences and perform poorly in capturing flow in the side lobes. These findings provide valuable insights into the interplay between acoustic field design and streaming dynamics, offering guidance for optimizing ultrasonic technologies in haptics and levitation applications.

physics.app-ph↗

arXiv2025

Spatial Sound Modulation through Manual Reconfiguration of Phased Plate

Ultrasonic phased array technology, while versatile, often requires complex computing resources and numerous amplifier components. We present a Manually Reconfigurable Phased Array that physically controls transducer position and phase, offering a simpler alternative to traditional phased array transducers (PAT). Our system uses a conductor rod-connected transducer array with an underlying plate that modulates the phase state through its shape and electrode arrangement. This approach enables variable phase reconstruction with reduced computational demands and lower cost. Experimental results demonstrate the device's capability to focus ultrasonic waves at different spatial locations. The system's design facilitates the creation of acoustic fields without extensive digital control, potentially broadening applications in areas such as aerial haptics, audio spotlighting, and educational demonstrations of acoustic phenomena. This work contributes to the development of more accessible and computationally efficient acoustic phased array systems.

physics.app-ph↗

arXiv2024

Mid-Air Single-Sided Acoustic Levitation in High-Pressure Regions of Zero-Order Bessel Beams

Acoustic levitation enables non-contact manipulation using sound waves. While conventional methods entrap particles at pressure nodes (zero-pressure region surrounded by high-pressure), we demonstrate stable acoustic levitation and translation in mid-air within a high-pressure axial core of a single-sided zero-order Bessel beam for the first time. The trap operates at a long working distance, up to 397 mm ($46.6 \lambda$), supports simultaneous multi-particle levitation, and maintains stability over obstacles. Our work establishes a new paradigm for single-sided acoustic manipulation in mid-air.

physics.app-ph↗

arXiv2024

Conditional neural holography: a distance-adaptive CGH generator

A convolutional neural network (CNN) is useful for overcoming the trade-off between generation speed and accuracy in the process of synthesizing computer-generated holograms (CGHs). However, methods using a CNN have limited applicability as they cannot specify the propagation distance when synthesizing a hologram. We developed a distance-adaptive CGH generator that can generate CGHs by specifying the target image and propagation distance, which comprises a zone plate encoder stage and an augmented HoloNet stage. Our model is comparable to that of prior CNN methods, with a fixed distance, in terms of performance and achieves the generation accuracy and speed necessary for practical use.

physics.optics↗

arXiv2024

Generative Artificial Intelligence-Guided User Studies: An Application for Air Taxi Services

User studies are crucial for meeting user needs. In user studies, real experimental scenarios and participants are constructed and recruited. However, emerging and unfamiliar studies face limitations, including safety concerns and iterative efficiency. To address these challenges, this study utilises a Generative Artificial Intelligence (GenAI) to create GenAI-generated scenarios for user experience (UX). By recruiting real users to evaluate this experience, we can collect feedback that enables rapid iteration in the early design phase. The air taxi is particularly representative of these challenges and has been chosen as the case study for this research. The key contribution was designing an Air Taxi Journey (ATJ) using Large Language Models (LLMs) and AI image and video generators. Based on the GPT-4-generated scripts, key visuals were created for the air taxi, and the ATJ was evaluated by 72 participants. Furthermore, the LLMs demonstrated the ability to identify and suggest environments that significantly improve participants' willingness toward air taxis. Education level and gender significantly influenced participants' the difference in willingness and their satisfaction with the ATJ. Satisfaction with the ATJ serves as a mediator, significantly influencing participants' willingness to take air taxis. Our study confirms the capability of GenAI to support user studies, providing a feasible approach and valuable insights for designing air taxi UX in the early design phase.

cs.HC↗

arXiv2023

Multi focus acoustic field generation using Dammann gratings for phased array transducers

Phased array transducers can shape acoustic fields for versatile manipulation; however, generating multiple focal points typically involves complex optimization. This study demonstrates that Dammann gratings - binary phase gratings originally used in optics to generate equal-intensity spot arrays - can be adapted for acoustics to create multiple equal-strength focal points with a phased array transducer. The transducer elements were assigned phases of 0 or {\pi}, based on a Dammann grating defined by its transition points. Simulations show that simple gratings with two transition points can generate fields with up to 12 focal points of nearly equal acoustic pressures. Compared to conventional multi-focus phase optimization techniques, the Dammann grating approach offers computational efficiency and facile reconfiguration of the focal pattern by adjusting the grating hologram. We tested this approach in numerical simulations with a hypothetical high-resolution array, achieving up to 12 focal points, and validated the efficacy of the Dammann grating in a conventional 16x16 transducer array through both simulations and experiments. This comparison highlights that while Dammann gratings effectively generate multi-focus fields, the recreation ability of these gratings in a conventional array shows a lower resolution than the hypothetical array. This study underlines the potential of adapting binary phase functions from photonics to enhance ultrasound-based acoustic manipulation for tasks requiring parallel actuation at multiple points.

physics.app-ph↗

arXiv2023

Dance Generation by Sound Symbolic Words

This study introduces a novel approach to generate dance motions using onomatopoeia as input, with the aim of enhancing creativity and diversity in dance generation. Unlike text and music, onomatopoeia conveys rhythm and meaning through abstract word expressions without constraints on expression and without need for specialized knowledge. We adapt the AI Choreographer framework and employ the Sakamoto system, a feature extraction method for onomatopoeia focusing on phonemes and syllables. Additionally, we present a new dataset of 40 onomatopoeia-dance motion pairs collected through a user survey. Our results demonstrate that the proposed method enables more intuitive dance generation and can create dance motions using sound-symbolic words from a variety of languages, including those without onomatopoeia. This highlights the potential for diverse dance creation across different languages and cultures, accessible to a wider audience. Qualitative samples from our model can be found at: https://sites.google.com/view/onomatopoeia-dance/home/.

cs.LG↗

arXiv2023

Towards Digital Nature: Bridging the Gap between Turing Machine Objects and Linguistic Objects in LLMMs for Universal Interaction of Object-Oriented Descriptions

In this paper, we propose a novel approach to establish a connection between linguistic objects and classes in Large Language Model Machines (LLMMs) such as GPT3.5 and GPT4, and their counterparts in high level programming languages like Python. Our goal is to promote the development of Digital Nature: a worldview where digital and physical realities are seamlessly intertwined and can be easily manipulated by computational means. To achieve this, we exploit the inherent abstraction capabilities of LLMMs to build a bridge between human perception of the real world and the computational processes that mimic it. This approach enables ambiguous class definitions and interactions between objects to be realized in programming and ubiquitous computing scenarios. By doing so, we aim to facilitate seamless interaction between Turing Machine objects and Linguistic Objects, paving the way for universally accessible object oriented descriptions. We demonstrate a method for automatically transforming real world objects and their corresponding simulations into language simulable worlds using LLMMs, thus advancing the digital twin concept. This process can then be extended to high level programming languages, making the implementation of these simulations more accessible and practical. In summary, our research introduces a groundbreaking approach to connect linguistic objects in LLMMs with high level programming languages, allowing for the efficient implementation of real world simulations. This ultimately contributes to the realization of Digital Nature, where digital and physical worlds are interconnected, and objects and simulations can be effortlessly manipulated through computational means.

cs.HC↗

arXiv2023

SHITARA: Sending Haptic Induced Touchable Alarm by Ring-shaped Air vortex

Social interaction begins with the other person's attention, but it is difficult for a d/Deaf or hard-of-hearing (DHH) person to notice the initial conversation cues. Wearable or visual devices have been proposed previously. However, these devices are cumbersome to wear or must stay within the DHH person's vision. In this study, we have proposed SHITARA, a novel accessibility method with air vortex rings that provides a non-contact haptic cue for a DHH person. We have developed a proof-of-concept device and determined the air vortex ring's accuracy, noticeability and comfortability when it hits a DHH's hair. Though strength, accuracy, and noticeability of air vortex rings decrease as the distance between the air vortex ring generator and the user increases, we have demonstrated that the air vortex ring is noticeable up to 2.5 meters away. Moreover, the optimum strength is found for each distance from a DHH.

cs.HC↗

arXiv2020

Acoustic Hologram Optimisation Using Automatic Differentiation

Acoustic holograms are the keystone of modern acoustics. It encodes three-dimensional acoustic fields in two dimensions, and its quality determine the performance of acoustic systems. Optimisation methods that control only the phase of an acoustic wave are considered inferior to methods that control both the amplitude and phase of the wave. In this paper, we present Diff-PAT, an acoustic hologram optimisation algorithm with automatic differentiation. We demonstrate that our method achieves superior accuracy than conventional methods. The performance of Diff-PAT was evaluated by randomly generating 1000 sets of up to 32 control points for single-sided arrays and single-axis arrays. The improved acoustic hologram can be used in wide range of applications of PATs without introducing any changes to existing systems that control the PATs. In addition, we applied Diff-PAT to acoustic metamaterial and achieved an >8 dB increase in the peak noise-to-signal ratio of acoustic hologram.

cs.SD↗