Handwriting Recognition in Free Space Using WIMU-Based Hand Motion Analysis

We present a wireless-inertial-measurement-unit- (WIMU-) based hand motion analysis technique for handwriting recognition in three-dimensional (3D) space. The proposed handwriting recognition system is not bounded by any limitations or constraints; users have the freedom and flexibility to write characters in free space. It uses hand motion analysis to segment hand motion data from a WIMU device that incorporates magnetic, angular rate, and gravity sensors (MARG) and a sensor fusion algorithm to automatically distinguish segments that represent handwriting from nonhandwriting data in continuous hand motion data. Dynamic time warping (DTW) recognition algorithm is used to recognize handwriting in real-time. We demonstrate that a user can freely write in air using an intuitive WIMU as an input and hand motion analysis device to recognize the handwriting in 3D space. The experimental results for recognizing handwriting in free space show that the proposed method is effective and efficient for other natural interaction techniques, such as in computer games and real-time hand gesture recognition applications

SCLAiR : Supervised Contrastive Learning for User and Device Independent Airwriting Recognition

Airwriting Recognition is the problem of identifying letters written in free space with finger movement. It is essentially a specialized case of gesture recognition, wherein the vocabulary of gestures corresponds to letters as in a particular language. With the wide adoption of smart wearables in the general population, airwriting recognition using motion sensors from a smart-band can be used as a medium of user input for applications in Human-Computer Interaction. There has been limited work in the recognition of in-air trajectories using motion sensors, and the performance of the techniques in the case when the device used to record signals is changed has not been explored hitherto. Motivated by these, a new paradigm for device and user-independent airwriting recognition based on supervised contrastive learning is proposed. A two stage classification strategy is employed, the first of which involves training an encoder network with supervised contrastive loss. In the subsequent stage, a classification head is trained with the encoder weights kept frozen. The efficacy of the proposed method is demonstrated through experiments on a publicly available dataset and also with a dataset recorded in our lab using a different device. Experiments have been performed in both supervised and unsupervised settings and compared against several state-of-the-art domain adaptation techniques. Data and the code for our implementation will be made available at https://github.com/ayushayt/SCLAiR

Towards streaming gesture recognition

The emergence of low-cost sensors allows more devices to be equipped with various types of sensors. In this way, mobile device such as smartphones or smartwatches now may contain accelerometers, gyroscopes, etc. This offers new possibilities for interacting with the environment and benefits would come to exploit these sensors. As a consequence, the literature on gesture recognition systems that employ such sensors grow considerably. The literature regarding online gesture recognition counts many methods based on Dynamic Time Warping (DTW). However, this method was demonstrated has non-efficient for time series from inertial sensors unit as a lot of noise is present. In this way new methods based on LCSS (Longest Common SubSequence) were introduced. Nevertheless, none of them focus on a class optimization process. In this master thesis, we present and evaluate a new algorithm for online gesture recognition in noisy streams. This technique relies upon the LM-WLCSS (Limited Memory and Warping LCSS) algorithm that has demonstrated its efficiency on gesture recognition. This new method involves a quantization step (via the K-Means clustering algorithm) that transforms new data to a finite set. In this way, each new sample can be compared to several templates (one per class). Gestures are rejected based on a previously trained rejection threshold. Thereafter, an algorithm, called SearchMax, find a local maximum within a sliding window and output whether or not the gesture has been recognized. In order to resolve conflicts that may occur, another classifier (i.e. C4.5) could be completed. As the K-Means clustering algorithm needs to be initialized with the number of clusters to create, we also introduce a straightforward optimization process. Such an operation also optimizes the window size for the SearchMax algorithm. In order to demonstrate the robustness of our algorithm, an experiment has been performed over two different data sets. However, results on tested data sets are only accurate when training data are used as test data. This may be due to the fact that the method is in an overlearning state. L’apparition de nouveaux capteurs à bas prix a permis d’en équiper dans beaucoup plus d’appareils. En effet, dans les appareils mobiles tels que les téléphones et les montres intelligentes nous retrouvons des accéléromètres, gyroscopes, etc. Ces capteurs présents dans notre vie quotidienne offrent de toutes nouvelles possibilités en matière d’interaction avec notre environnement et il serait avantageux de les utiliser. Cela a eu pour conséquence une augmentation considérable du nombre de recherches dans le domaine de reconnaissance de geste basé sur ce type de capteur. La littérature concernant la reconnaissance de gestes en ligne comptabilise beaucoup de méthodes qui se basent sur Dynamic Time Warping (DTW). Cependant, il a été démontré que cette méthode se révèle inefficace en ce qui concerne les séries temporelles provenant d’une centrale à inertie puisqu’elles contiennent beaucoup de bruit. En ce sens de nouvelles méthodes basées sur LCSS (Longest Common SubSequence) sont apparues. Néanmoins, aucune d’entre elles ne s’est focalisée sur un processus d’optimisation par class. Ce mémoire de maîtrise consiste en une présentation et une évaluation d’un nouvel algorithme pour la reconnaissance de geste en ligne avec des données bruitées. Cette technique repose sur l’algorithme LM-WLCSS (Limited Memory and Warping LCSS) qui a d’ores et déjà démontré son efficacité quant à la reconnaissance de geste. Cette nouvelle méthode est donc composée d’une étape dite de quantification (grâce à l’algorithme de regroupement K-Means) qui se charge de convertir les nouvelles données entrantes vers un ensemble de données fini. Chaque nouvelle donnée peut donc être comparée à plusieurs motifs (un par classe) et un geste est reconnu dès lors que son score dépasse un seuil préalablement entrainé. Puis, un autre algorithme appelé SearchMax se charge de trouver un maximum local au sein d’une fenêtre glissant afin de préciser si oui ou non un geste a été reconnu. Cependant des conflits peuvent survenir et en ce sens un autre classifieur (c.-àd. C4.5) est chainé. Étant donné que l’algorithme de regroupement K-Means a besoin d’une valeur pour le nombre de regroupements à faire, nous introduisons également une technique simple d’optimisation à ce sujet. Cette partie d’optimisation se charge également de trouver la meilleure taille de fenêtre possible pour l’algorithme SearchMax. Afin de démontrer l’efficacité et la robustesse de notre algorithme, nous l’avons testé sur deux ensembles de données différents. Cependant, les résultats sur les ensembles de données testées n’étaient bons que lorsque les données d’entrainement étaient utilisées en tant que données de test. Cela peut être dû au fait que la méthode est dans un état de surapprentissage

Activity-Based User Authentication Using Smartwatches

Smartwatches, which contain an accelerometer and gyroscope, have recently been used to implement gait and gesture- based biometrics; however, the prior studies have long-established drawbacks. For example, data for both training and evaluation was captured from single sessions (which is not realistic and can lead to overly optimistic performance results), and in cases when the multi-day scenario was considered, the evaluation was often either done improperly or the results are very poor (i.e., greater than 20% of EER). Moreover, limited activities were considered (i.e., gait or gestures), and data captured within a controlled environment which tends to be far less realistic for real world applications. Therefore, this study remedies these past problems by training and evaluating the smartwatch-based biometric system on data from different days, using large dataset that involved the participation of 60 users, and considering different activities (i.e., normal walking (NW), fast walking (FW), typing on a PC keyboard (TypePC), playing mobile game (GameM), and texting on mobile (TypeM)). Unlike the prior art that focussed on simply laboratory controlled data, a more realistic dataset, which was captured within un-constrained environment, is used to evaluate the performance of the proposed system. Two principal experiments were carried out focusing upon constrained and un-constrained environments. The first experiment included a comprehensive analysis of the aforementioned activities and tested under two different scenarios (i.e., same and cross day). By using all the extracted features (i.e., 88 features) and the same day evaluation, EERs of the acceleration readings were 0.15%, 0.31%, 1.43%, 1.52%, and 1.33% for the NW, FW, TypeM, TypePC, and GameM respectively. The EERs were increased to 0.93%, 3.90%, 5.69%, 6.02%, and 5.61% when the cross-day data was utilized. For comparison, a more selective set of features was used and significantly maximize the system performance under the cross day scenario, at best EERs of 0.29%, 1.31%, 2.66%, 3.83%, and 2.3% for the aforementioned activities respectively. A realistic methodology was used in the second experiment by using data collected within unconstrained environment. A light activity detection approach was developed to divide the raw signals into gait (i.e., NW and FW) and stationary activities. Competitive results were reported with EERs of 0.60%, 0% and 3.37% for the NW, FW, and stationary activities respectively. The findings suggest that the nature of the signals captured are sufficiently discriminative to be useful in performing transparent and continuous user authentication.University of Kuf

Contributions to non-conventional biometric systems : improvements on the fingerprint, facial and handwriting recognition approach

Tese (doutorado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Mecânica, 2021.Os sistemas biométricos são amplamente utilizados pela sociedade. A maioria das aplicações desses sistemas está associada à identificação civil e à investigação criminal. No entanto, com o tempo, o desempenho dos métodos tradicionais de biometria está chegando ao limite. Neste contexto, sistemas biométricos emergentes ou não convencionais estão ganhando importância. Embora promissores, novos sistemas, assim como qualquer nova tecnologia, trazem consigo não apenas potencialidades, mas também fragilidades. Este trabalho apresenta contribuições para três importantes sistemas biométricos não convencionais (SBNC): impressão digital, reconhecimento facial e reconhecimento de escrita. No que diz respeito às impressões digitais, este trabalho apresenta um novo método para detectar a vida em dispositivos de impressão digital multivista sem toque, utilizando descritores de textura e redes neurais artificiais. Com relação ao reconhecimento facial, um método de reconhecimento de faces baseado em algoritmos de característica invariante à escala (SIFT e SURF) que opera sem a necessidade de treinamento prévio do classificador e que realiza o rastreamento de indivíduos em ambientes não controlados é apresentado. Finalmente, um método de baixo custo que usa sinais de acelerômetro e giroscópio obtidos a partir de um sensor acoplado a canetas convencionais para realizar o reconhecimento em tempo real de assinaturas é apresentado. Resultados mostram que os métodos propostos são promissores e que juntos podem contribuir para o aprimoramento dos SBNCCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).Biometric systems are widely used by society. Most applications are associated with civil identification and criminal investigation. However, over time, traditional methods of performing biometrics have been reaching their limits. In this context, emerging or nonconventional biometric systems (NCBS) are gaining ground. Although promising, new systems, as well as any new technology, bring not only potentialities but also weaknesses. This work presents contributions to three important non-conventional biometric systems: fingerprint, facial, and handwriting recognition. With regard to fingerprints, this work presents a novel method for detecting life on Touchless Multi-view Fingerprint Devices, using Texture Descriptors and Artificial Neural Networks. With regard to face recognition, a facial recognition method is presented, based on Scale Invariant Feature Algorithms (SIFT and SURF), that operates without the need of previous training of a classifier and can be used to track individuals in an unconstrained environment. Finally, a low-cost on-line handwriting signature recognition method that uses accelerometer and gyroscope signals obtained from a sensor coupled to conventional pens to identify individuals in real time is presented. Results show that the proposed methods are promising and that together may contribute to the improvement of the NCB

Wearable Smart Rings for Multi-Finger Gesture Recognition Using Supervised Learning

This thesis presents a wearable, smart ring with an integrated Bluetooth low-energy (BLE) module. The system uses an accelerometer and a gyroscope to collect fingers motion data. A prototype was manufactured, and its performance was tested. To detect complex finger movements, two rings are worn on the point and thumb fingers while performing the gestures. Nine pre-defined finger movements were introduced to verify the feasibility of the proposed method. Data pre-processing techniques, including normalization, statistical feature extraction, random forest recursive feature elimination (RF-RFE), and k-nearest neighbors sequential forward floating selection (KNN-SFFS), were applied to select well-distinguished feature vectors to enhance gesture recognition accuracy. Three supervised machine learning algorithms were used for gesture classification purposes, namely Support Vector Machine (SVM), K-Nearest Neighbors (KNN), and Naive Bayes (NB). We demonstrated that when utilizing the KNN-SFFS recommended features as the machine learning input, our proposed finger gesture recognition approach not only significantly decreases the dimension of the feature vector, results in faster response time and prevents overfitted model, but also provides approximately similar machine learning prediction accuracy compared to when all elements of feature vectors were used. By using the KNN as the primary classifier, the system can accurately recognize six one-finger and three two-finger gestures with 97.1% and 97.0% accuracy, respectively

Integrating passive ubiquitous surfaces into human-computer interaction

Mobile technologies enable people to interact with computers ubiquitously. This dissertation investigates how ordinary, ubiquitous surfaces can be integrated into human-computer interaction to extend the interaction space beyond the edge of the display. It turns out that acoustic and tactile features generated during an interaction can be combined to identify input events, the user, and the surface. In addition, it is shown that a heterogeneous distribution of different surfaces is particularly suitable for realizing versatile interaction modalities. However, privacy concerns must be considered when selecting sensors, and context can be crucial in determining whether and what interaction to perform.Mobile Technologien ermöglichen den Menschen eine allgegenwärtige Interaktion mit Computern. Diese Dissertation untersucht, wie gewöhnliche, allgegenwärtige Oberflächen in die Mensch-Computer-Interaktion integriert werden können, um den Interaktionsraum über den Rand des Displays hinaus zu erweitern. Es stellt sich heraus, dass akustische und taktile Merkmale, die während einer Interaktion erzeugt werden, kombiniert werden können, um Eingabeereignisse, den Benutzer und die Oberfläche zu identifizieren. Darüber hinaus wird gezeigt, dass eine heterogene Verteilung verschiedener Oberflächen besonders geeignet ist, um vielfältige Interaktionsmodalitäten zu realisieren. Bei der Auswahl der Sensoren müssen jedoch Datenschutzaspekte berücksichtigt werden, und der Kontext kann entscheidend dafür sein, ob und welche Interaktion durchgeführt werden soll

Hybrid wheelchair controller for handicapped and quadriplegic patients

In this dissertation, a hybrid wheelchair controller for handicapped and quadriplegic patient is proposed. The system has two sub-controllers which are the voice controller and the head tilt controller. The system aims to help quadriplegic, handicapped, elderly and paralyzed patients to control a robotic wheelchair using voice commands and head movements instead of a traditional joystick controller. The multi-input design makes the system more flexible to adapt to the available body signals. The low-cost design is taken into consideration as it allows more patients to use this system

Low-Cost Sensors and Biological Signals

Many sensors are currently available at prices lower than USD 100 and cover a wide range of biological signals: motion, muscle activity, heart rate, etc. Such low-cost sensors have metrological features allowing them to be used in everyday life and clinical applications, where gold-standard material is both too expensive and time-consuming to be used. The selected papers present current applications of low-cost sensors in domains such as physiotherapy, rehabilitation, and affective technologies. The results cover various aspects of low-cost sensor technology from hardware design to software optimization