Imperial College London

DrRebeccaStewart

Faculty of EngineeringDyson School of Design Engineering

Senior Lecturer in Interactive Systems
 
 
 
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Contact

 

r.stewart Website

 
 
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Location

 

1M02Royal College of ScienceSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
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19 results found

Li Y, Zhou Y, Shen C, Stewart Ret al., 2024, E-textile sleeve with graphene strain sensors for arm gesture classification of mid-air interactions, TEI '24: Eighteenth International Conference on Tangible, Embedded, and Embodied Interaction, Publisher: ACM, Pages: 1-10

Arm gestures play a pivotal role in facilitating natural mid-air interactions. While computer vision techniques aim to detect these gestures, they encounter obstacles like obfuscation and lighting conditions. Alternatively, wearable devices have leveraged interactive textiles to recognize arm gestures. However, these methods predominantly emphasize textile deformation-based interactions, like twisting or grasping the sleeve, rather than tracking the natural body movement.This study bridges this gap by introducing an e-textile sleeve system that integrates multiple ultra-sensitive graphene e-textile strain sensors in an arrangement that captures bending and twisting along with an inertia measurement unit into a sports sleeve. This paper documents a comprehensive overview of the sensor design, fabrication process, seamless interconnection method, and detachable hardware implementation that allows for reconfiguring the processing unit to other body parts. A user study with ten participants demonstrated that the system could classify six different fundamental arm gestures with over 90% accuracy.

Conference paper

Dave RJ, Min X, Lou Z, Stewart Ret al., 2024, Investigating construction and integration techniques of dry silver-based textile electrodes on electromyography of biceps Brachii muscle, 5th International Conference on the Challenges, Opportunities, Innovations and Applications in Electronic Textiles, Publisher: MDPI, ISSN: 2673-4591

This research paper recommends an electrode construction and integration technique for dry silver-based textile electrodes capturing electromyographic (EMG) signals. Three integration methods with two different conductive textiles were compared using two analysis methods; analysis was also conducted before and after six washing cycles. Six wearable arm bands with each of the design parameter combinations were worn on the biceps brachii muscle to capture EMG signals from three users under a controlled task both before any washing of the bands occurred and after four washing cycles were completed. Additionally, impedance measurements over six frequency bands were recorded after each washing cycle. Textile electrodes made of Shieldex Techniktex P180B using an extended electrode integration method were found to perform best.

Conference paper

Zhang M, Stewart R, Bryan-Kinns N, 2024, Empowering textile and fashion designers with e-textiles for creative expression, 5th International Conference on the Challenges, Opportunities, Innovations and Applications in Electronic Textiles, Publisher: MDPI, ISSN: 2673-4591

In the field of textile and fashion design, there is a growing desire to integrate interactive technologies into creative work. Traditional design education typically lacks support for material-oriented designers to develop electronic skills alongside their expertise in materials. There is a need to develop proper support for these designers to enter the world of electronic textiles (e-textiles). Our previous work introduced a material-centred e-textile learning approach through the development of a toolkit. This paper offers a glimpse into a design project made by our students, where digital functionality intertwines with physical design. It serves as a testament to the effectiveness of our approach in merging interactive technology concepts with material expertise, thereby aiding these designers in their creative endeavours.

Conference paper

Aziz N, Stockman T, Stewart R, 2022, Planning your journey in audio: design and evaluation of auditory route overviews, ACM Trans. Access. Comput., Vol: 15, Pages: 1-48, ISSN: 1936-7228

Auditory overviews of routes can provide routing and map information to blind users enabling them to preview route maps before embarking on a journey. This paper investigates the usefulness of a system designed to do this through a Preliminary Survey, followed by a Design Study to gather the design requirements, development of a prototype and evaluation through a Usability Study. The design is drawn in 2-stages with 8 audio designers and 8 potential blind users. The auditory route overview is sequential and automatically generated as integrated audio. It comprises auditory icons to represent points of interest, earcons for auditory brackets encapsulating repeating points of interest, and speech for directions. A prototype based on this design is developed and evaluated with 22 sighted and 8 blind participants. The software architecture of the prototype including the route information retrieval and mapping onto audio has been included. The findings show that both groups perform well in route reconstruction and recognition tasks. Moreover, the functional route information and auditory icons are effectively designed and useful in forming a mental model of the route, which improves over time. However, the design of auditory brackets needs further improvement and testing. At all stages of the system development, input has been acquired from the end-user population and the design is adapted accordingly.

Journal article

Zhou Y, Stewart R, 2022, Highly flexible, durable, UV resistant, and electrically conductive graphene based TPU/textile composite sensor, Polymers for Advanced Technologies, Vol: 33, Pages: 4250-4264, ISSN: 1042-7147

Flexible strain sensors have attracted considerable attention due to their applications in wearable monitoring fields such as human-computer interaction systems, athletic training, and health systems. Textiles are a desired substrate for fabricating wearable flexible sensors due to their light weight, comfort, and flexibility. However, the compatibility between textiles and conductive materials still faces critical challenges, especially for wearable sensors to achieve high sensitivity and a wide sensing range simultaneously with long-term monitoring stability, reliability, and wearing comfort. In this study, we propose a graphene-based TPU/textile composite sensor that can be produced using small-scale manufacturing techniques, using laser cutting combined with film coating and thermal transfer processes and further explore its mechanical, electrical, and sensing properties. Since the human body exhibits different magnitudes of motion and fabric sensors integrated into clothing would face multiple challenges in real world usage e.g. repetitive wear, sweat and sunlight exposure, we performed sensitivity, reliability and durability tests to further evaluate real world usage of the fabric sensors. The developed composite sensor exhibits a high sensitivity (GF = 498), wide sensing range (0%–293%), excellent reliability and stability which only shows 5% deviation after 10,000 cycles of stretching under 5% strain. In addition, the graphene-based textile composite sensor thermalised by TPU film can also maintain high stability after long-term UV irradiation and multiple washing cycles. When integrated into various wearable devices, our composite sensor can detect a wide range of human body motions accurately, as well as subtle physiological signals, exhibiting great potential in incorporating into wearable monitoring devices.

Journal article

Mao A, Giraudet CSE, Liu K, De Almeida Nolasco I, Xie Z, Xie Z, Gao Y, Theobald J, Bhatta D, Stewart R, McElligott AGet al., 2022, Automated identification of chicken distress vocalizations using deep learning models., Journal of the Royal Society Interface, Vol: 19, Pages: 1-11, ISSN: 1742-5662

The annual global production of chickens exceeds 25 billion birds, which are often housed in very large groups, numbering thousands. Distress calling triggered by various sources of stress has been suggested as an 'iceberg indicator' of chicken welfare. However, to date, the identification of distress calls largely relies on manual annotation, which is very labour-intensive and time-consuming. Thus, a novel convolutional neural network-based model, light-VGG11, was developed to automatically identify chicken distress calls using recordings (3363 distress calls and 1973 natural barn sounds) collected on an intensive farm. The light-VGG11 was modified from VGG11 with significantly fewer parameters (9.3 million versus 128 million) and 55.88% faster detection speed while displaying comparable performance, i.e. precision (94.58%), recall (94.89%), F1-score (94.73%) and accuracy (95.07%), therefore more useful for model deployment in practice. To additionally improve light-VGG11's performance, we investigated the impacts of different data augmentation techniques (i.e. time masking, frequency masking, mixed spectrograms of the same class and Gaussian noise) and found that they could improve distress calls detection by up to 1.52%. Our distress call detection demonstration on continuous audio recordings, shows the potential for developing technologies to monitor the output of this call type in large, commercial chicken flocks.

Journal article

Zhou Y, Myant C, Stewart R, 2022, Multifunctional and stretchable graphene/textile composite sensor for human motion monitoring, Journal of Applied Polymer Science, Vol: 139, ISSN: 0021-8995

Sensors based on electronic textiles (e-textiles) have become increasingly prominent in the field of biomechanical monitoring technology due to multiple properties such as being lightweight, flexible, and comfortable, with increasing potential in incorporating into long-term monitoring devices. Previous research has been conducted into textile strain sensors based on graphene for human motion monitoring, however most graphene e-textile strain sensors exhibit poor sensitivity and stretchability. To our knowledge, no previous research has looked at knitted graphene-based fabrics in regards to the fabric composition of the substrate. In this paper, we propose a graphene/fabric composite sensor using a cost-effective dip coating method of an acrylic/Spandex knit fabric, and further explores its mechanical, electrical, and sensing properties. The developed graphene/textile composite sensor has a wide sensing range (up to 344%) and exhibits a good sensitivity with a high gauge factor of up to 16. As a wearable sensor, our sensing fabric can detect both large and subtle human motions and is able to distinguish between various ranges of joint movements, demonstrating its ability to function as a human motion monitoring system. Our sensor further exhibits the ability to be used as a supercapacitor or capacitive pressure sensor.

Journal article

Zhang M, Stewart R, Bryan-Kinns N, 2022, Integrating interactive technology concepts with material expertise in textile design disciplines, New York, NY, USA, DIS '22: Designing Interactive Systems Conference, Publisher: Association for Computing Machinery, Pages: 1277-1287

Textile and fashion designers are increasingly interested in integrating interactive technologies into their practice. However, traditional design education typically lacks support for them to develop technical digital and electronics skills alongside their expertise in materials. Reflecting on outputs from an e-textile design workshop and 8-week design projects with four textile design students using an e-textile toolkit, and follow-up data collection with the students one year after the projects, we argue that starting technical explorations with raw materials results in a better understanding and more flexible use of technical knowledge. We also argue that this newly acquired knowledge is then more fully integrated with their pre-existing material knowledge as it is applied to physical interface design. The results contribute to the development of tools and approaches in supporting designers with material expertise to learn tangible interaction design skills.

Conference paper

Zhou Y, Zhang C, Myant C, Stewart Ret al., 2022, Knitted Graphene Supercapacitor and Pressure-Sensing Fabric †

This research utilizes a simple and effective dip coating/ultrasonication method to prepare porous graphene-coated sensing fabrics made with commercially produced acrylic/spandex yarn with multifunctional performance. We examine the electrochemical performance of graphene-coated fabrics and explore their potential in applications involving pressure sensors. The results show that our graphene-coated fabric demonstrates a maximum specific capacitance value of 17.4 F/g. When applied as a pressure sensor, the capacitance change rate of our sensor increases linearly with the increase in pressure applied to the fabrics. Our sensor also shows a fast response in a pressure loading–unloading test, which indicates an outstanding sensing property and shows promising capabilities as a supercapacitor.

Conference paper

Yeoward C, Shukla R, Stewart R, Sandler M, Reiss JDet al., 2021, Real-time binaural room modeling for augmented reality applications, Journal of the Audio Engineering Society, Vol: 69, Pages: 818-833, ISSN: 0004-7554

This paper proposes and evaluates an integrated method for real-time, head-tracked, 3D binaural audio with synthetic reverberation. Virtual vector base amplitude panning is used to position the sound source and spatialize outputs from a scattering delay network reverb algorithm running in parallel. A unique feature of this approach is its realization of interactive auralization using vector base amplitude panning and a scattering delay network, within acceptable levels of latency, at low computational cost. The rendering model also allows direct parameterization of room geometry and absorption characteristics. Varying levels of reverb complexity can be implemented, and these were evaluated against two distinct aspects of perceived sonic immersion. Outcomes from the evaluation provide benchmarks for how the approach could be deployed adaptively, to balance three real-time spatial audio objectives of envelopment, naturalness, and efficiency, within contrasting physical spaces

Journal article

Skach S, Healey PGT, Stewart R, 2021, Sensing social behavior with smart trousers, IEEE Pervasive Computing, Vol: 20, Pages: 30-40, ISSN: 1536-1268

Nonverbal signals play an important role in social interaction. Body orientation, posture, hand, and leg movements all contribute to successful communication, though research has typically focused on cues transmitted from the torso alone. Here, we explore lower body movements and address two issues. First, the empirical question of what social signals they provide. Second, the technical question of how these movements could be sensed unintrusively and in situations where traditional methods prove challenging. To approach these issues, we propose a soft, wearable sensing system for clothing. Bespoke “smart” trousers with embedded textile pressure sensors are designed and deployed in seated, multiparty conversations. Using simple machine learning techniques and evaluating individual and community models, our results show that it is possible to distinguish basic conversational states. With the trousers picking up speaking, listening, and laughing, they present an appropriate modality to ubiquitously sense human behavior.

Journal article

Liang A, Stewart R, Freire R, Bryan-Kinns Net al., 2021, Knit Stretch Sensor Placement for Body Movement Sensing, Proceedings of the Fifteenth International Conference on Tangible, Embedded, and Embodied Interaction

Conference paper

Liang A, Stewart R, Bryan-Kinns N, 2019, Analysis of sensitivity, linearity, hysteresis, responsiveness, and fatigue of textile knit stretch sensors, Sensors, Vol: 19, Pages: 1-20, ISSN: 1424-8220

Wearable technology is widely used for collecting information about the human body and its movement by placing sensors on the body. This paper presents research into electronic textile strain sensors designed specifically for wearable applications which need to be lightweight, robust, and comfortable. In this paper, sixteen stretch sensors, each with different conductive stretch fabrics, are evaluated: EeonTex (Eeonyx Corporation), knitted silver-plated yarn, and knitted spun stainless steel yarn. The sensors’ performance is tested using a tensile tester while monitoring their resistance with a microcontroller. Each sensor was analyzed for its sensitivity, linearity, hysteresis, responsiveness, and fatigue through a series of dynamic and static tests. The findings show that for wearable applications a subset of the silver-plated yarn sensors had better ranked performance in terms of sensitivity, linearity, and steady state. EeonTex was found to be the most responsive, and the stainless steel yarn performed the worst, which may be due to the characteristics of the knit samples under test.

Journal article

Mcloughlin MP, Stewart R, McElligott AG, 2019, Automated bioacoustics: methods in ecology and conservation and their potential for animal welfare monitoring, Journal of The Royal Society Interface, Vol: 16, Pages: 1-12, ISSN: 1742-5689

Vocalizations carry emotional, physiological and individual information. This suggests that they may serve as potentially useful indicators for inferring animal welfare. At the same time, automated methods for analysing and classifying sound have developed rapidly, particularly in the fields of ecology, conservation and sound scene classification. These methods are already used to automatically classify animal vocalizations, for example, in identifying animal species and estimating numbers of individuals. Despite this potential, they have not yet found widespread application in animal welfare monitoring. In this review, we first discuss current trends in sound analysis for ecology, conservation and sound classification. Following this, we detail the vocalizations produced by three of the most important farm livestock species: chickens (Gallus gallus domesticus), pigs (Sus scrofa domesticus) and cattle (Bos taurus). Finally, we describe how these methods can be applied to monitor animal welfare with new potential for developing automated methods for large-scale farming.

Journal article

Stewart R, 2019, Cords and chords: exploring the role of E-textiles in computational audio, Frontiers in ICT, Vol: 6, Pages: 1-12, ISSN: 2297-198X

Electronic textiles (e-textiles) have played a significant role in computational audio ranging from wearable interfaces for creative expression to more utilitarian purposes such as acoustic monitoring for military applications. This article looks at e-textiles within computational audio from three perspectives: the historical developments of the field; the core enabling technologies; and the primary application areas. It closes with a discussion of what role e-textiles may play in future computational audio systems.

Journal article

Skach S, Stewart R, 2019, One Leg at a Time: Towards Optimised Design Engineering of Textile Sensors in Trousers, ACM International Joint Conference on Pervasive and Ubiquitous Computing (UbiComp) / ACM International Symposium on Wearable Computers (ISWC), Publisher: ASSOC COMPUTING MACHINERY, Pages: 206-209

Conference paper

Liang A, Stewart R, Freire R, Bryan-Kinns Net al., 2019, Effect of Bonding and Washing on Electronic Textile Stretch Sensor Properties, ACM International Joint Conference on Pervasive and Ubiquitous Computing (UbiComp) / ACM International Symposium on Wearable Computers (ISWC), Publisher: ASSOC COMPUTING MACHINERY, Pages: 121-124

Conference paper

Stewart R, Skach S, Bin A, 2018, Making grooves with needles: Using e-textiles to encourage gender diversity in embedded audio systems design, 2018 Designing Interactive Systems Conference, Publisher: ACM Press, Pages: 163-172

Historically, women have been excluded from engineering and computer science disciplines, and interactive audio is no exception. Relatively few women are involved with the designing and building of embedded audio systems with traditional tools such as microprocessors, but when embedded audio systems are built using e-textiles, much larger proportions of women become engaged with technology. In this paper we review theories for this gender disparity and the barriers women face in working with audio technology, and then present a comparison of survey data between an e-textile audio workshop and an audio platform user group. Extrapolating from the case study and the surveyed literature, we propose that flexibility in learning, communal dissemination of knowledge, and gendering of tools are prominent reasons why women engage with technology via e-textiles.

Conference paper

McArthur A, Stewart R, Sandler M, 2017, Sounds too true to be good: diegetic infidelity–the case for sound in virtual reality, Journal of Media Practice, Vol: 18, Pages: 26-40, ISSN: 1468-2753

Published by Informa UK Limited, trading as Taylor & Francis Group. Cinematic virtual reality (VR) elicits new possibilities for the treatment of sound in space. Distinct from screen-based practices of filmmaking, diegetic sound–image relations in immersive environments present unique, potent affordances, in which content is at once imaginary, and real. However, a reductive modelling of environmental realism, in the name of ‘presence’ predominates. Yet cross-modal perception is a noisy, flickering representation of worlds. Treating our perceptual apparatus as stable, objective transducers, ignores the inter-subjective potential at the heart of immersive work, and situates users as passive spectators. This condescends to audiences and discounts the historic symbiosis of sound–image signification, which comes to constitute notions of verisimilitude. We understand the tropes; we willingly suspend disbelief. This article examines spatial sound rendering in virtual environments, probing at diegetic realism. It calls for an experimental, aesthetic approach, suggesting several speculative strategies, drawing from theories of embodied cognition and acousmatic practice (amongst others) which necessarily deal with space and time as contingencies of the immersive. VR affords a development of the dialectic between sound and image which distinctively involves our spatial attention. The lines between referent and signified blur; the mediation between representations invoked by practitioners, and those experienced by audiences, suggest new opportunities for co-authorship.

Journal article

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