Drawing, Handwriting Processing Analysis: New Advances and Challenges

International audienceDrawing and handwriting are communicational skills that are fundamental in geopolitical, ideological and technological evolutions of all time. drawingand handwriting are still useful in defining innovative applications in numerous fields. In this regard, researchers have to solve new problems like those related to the manner in which drawing and handwriting become an efficient way to command various connected objects; or to validate graphomotor skills as evident and objective sources of data useful in the study of human beings, their capabilities and their limits from birth to decline

Variations of handwritten signatures with time: A sigma-lognormal analysis

Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. M. Gómez-Barrero, J. Galbally, J. Fiérrez, J. Ortega-García, "Variations of handwritten signatures with time: A sigma-lognormal analysis" in 6th International Conference on Biometrics (ICB), Madrid (Spain), 2013, 1-6The variation of dynamic signatures with time is analysed for the first time using the Kinematic Theory, following a general, consistent and fully reproducible protocol. Experiments are carried out on a new long-term database captured in 6 sessions uniformly distributed over a 15 month time span, under almost identical conditions. Signatures are represented with the Sigma Log-Normal model, which takes into account the effects of body ageing closely related to handwriting, such as neuromuscular response times. After studying the evolution of signatures with time, an analysis on age groups based on the model parameters is carried out.This work has been partially supported by projects Contexts (S2009/TIC-1485) from CAM, Bio-Challenge (TEC2009-11186) and Bio-Shield (TEC2012-34881) from Spanish MINECO, Guardia Civil, Cátedra UAM-Telefónica and grant RGPIN-915 from NSERC Canada

A new algorithm and system for the extraction of delta-lognormal parameters

In this report, we present a new analytical method to estimate the parameters of Delta-lognormal functions. According to the Kinematic Theory of rapid human movements, these parameters contain information both on the motor commands and on the timing properties of a neuromuscular system. The new algorithm, called XZERO, exploits relationships between the zero crossings of the first and the second time-derivatives of a lognormal function and its four basic parameters. The methodology is described and evaluated in various testing conditions. Furthermore, for the first time, the extraction accuracy is quantified empirically, taking advantage of the exponential relationships that link the disperssion of the extraction errors with its signal to noise ratio. A new extraction system, which uses a benchmark of three estimation methods, is also proposed and evaluated in the mid-term perspective of developing machine intelligence applications that rely on lognormal functions

Active detection of age groups based on touch interaction

This paper studies user classification into children and adults according to their interaction with touchscreen devices. We analyse the performance of two sets of features derived from the Sigma-Lognormal theory of rapid human movements and global characterization of touchscreen interaction. We propose an active detection approach aimed to continuously monitorize the user patterns. The experimentation is conducted on a publicly available database with samples obtained from 89 children between 3 and 6 years old and 30 adults. We have used Support Vector Machines algorithm to classify the resulting features into age groups. The sets of features are fused at score level using data from smartphones and tablets. The results, with correct classification rates over 96%, show the discriminative ability of the proposed neuromotorinspired features to classify age groups according to the interaction with touch devices. In active detection setup, our method is able to identify a child using only 4 gestures in averageThis work was funded by the project CogniMetrics (TEC2015-70627-R) and Bio-Guard (Ayudas Fundación BBVA a Equipos de Investigación Científica 2017

Influence of Mother Tongue on Dynamic Handwriting Features in Primary School

Handwriting is an essential fine motor skill in school-aged children and plays a crucial role for educational development and autonomy of everyday life. To analyze hand-writing movement an objective quantitative kinematic analysis can be performed by using digital tablets. Through this tech-nology it was possible to identify a lot of parameters useful to characterize the handwriting process. In order to study the influence of mother tongue on the dy-namic of handwriting in primary school, we examined the writing response of 42 non-native speakers and compared their characteristics with those of 131 Italian mother tongue chil-dren. All children undertook one repetitive sequence of le and an Italian sentence written in two different ways: as accurately as and as fast as possible. The results showed that the differences between native and non-native speakers were not significant in the repetitive se-quence while a clear influence of mother tongue was present only in the third grade for the sentence tasks

Capturing the Cranio-Caudal Signature of a Turn with Inertial Measurement Systems: Methods, Parameters Robustness and Reliability

BACKGROUND: Turning is a challenging mobility task requiring coordination and postural stability. Optimal turning involves a cranio-caudal sequence (i.e., the head initiates the motion, followed by the trunk and the pelvis), which has been shown to be altered in patients with neurodegenerative diseases, such as Parkinson's disease as well as in fallers and frails. Previous studies have suggested that the cranio-caudal sequence exhibits a specific signature corresponding to the adopted turn strategy. Currently, the assessment of cranio-caudal sequence is limited to biomechanical labs which use camera-based systems; however, there is a growing trend to assess human kinematics with wearable sensors, such as attitude and heading reference systems (AHRS), which enable recording of raw inertial signals (acceleration and angular velocity) from which the orientation of the platform is estimated. In order to enhance the comprehension of complex processes, such as turning, signal modeling can be performed. AIM: The current study investigates the use of a kinematic-based model, the sigma-lognormal model, to characterize the turn cranio-caudal signature as assessed with AHRS. METHODS: Sixteen asymptomatic adults (mean age = 69.1 +/- 7.5 years old) performed repeated 10-m Timed-Up-and-Go (TUG) with 180 degrees turns, at varying speed. Head and trunk kinematics were assessed with AHRS positioned on each segments. Relative orientation of the head to the trunk was then computed for each trial and relative angular velocity profile was derived for the turn phase. Peak relative angle (variable) and relative velocity profiles modeled using a sigma-lognormal approach (variables: Neuromuscular command amplitudes and timing parameters) were used to extract and characterize the cranio-caudal signature of each individual during the turn phase. RESULTS: The methodology has shown good ability to reconstruct the cranio-caudal signature (signal-to-noise median of 17.7). All variables were robust to speed variations (p > 0.124). Peak relative angle and commanded amplitudes demonstrated moderate to strong reliability (ICC between 0.640 and 0.808). CONCLUSION: The cranio-caudal signature assessed with the sigma-lognormal model appears to be a promising avenue to assess the efficiency of turns

AutoGraff: towards a computational understanding of graffiti writing and related art forms.

The aim of this thesis is to develop a system that generates letters and pictures with a style that is immediately recognizable as graffiti art or calligraphy. The proposed system can be used similarly to, and in tight integration with, conventional computer-aided geometric design tools and can be used to generate synthetic graffiti content for urban environments in games and in movies, and to guide robotic or fabrication systems that can materialise the output of the system with physical drawing media. The thesis is divided into two main parts. The first part describes a set of stroke primitives, building blocks that can be combined to generate different designs that resemble graffiti or calligraphy. These primitives mimic the process typically used to design graffiti letters and exploit well known principles of motor control to model the way in which an artist moves when incrementally tracing stylised letter forms. The second part demonstrates how these stroke primitives can be automatically recovered from input geometry defined in vector form, such as the digitised traces of writing made by a user, or the glyph outlines in a font. This procedure converts the input geometry into a seed that can be transformed into a variety of calligraphic and graffiti stylisations, which depend on parametric variations of the strokes

The Lognometer: A New Normalized and Computerized Device for Assessing the Neurodevelopment of Fine Motor Control in Children

Motor skills are fundamental for the development of children. Neurodevelopmental tests currently used by professionals for measuring motor control maturity exhibit several limitations. To address some of these, we have designed the Lognometer, a tablet-based device that can run computerized neuromotor tests. To normalize this tool against a representative population, we collected handwritten triangles from 780 children. We used the Sigma-Lognormal model and a prototype-based parameter estimation algorithm to analyze these movements. To ensure clinical acceptance, we developed an explainable solution relying on statistical regression. We evaluated how well the proposed lognormal decomposition captures the motor control maturation between 6 to 13 years of age by plotting the biological age versus the age estimated using movement kinematics. To provide an equivalent to growth curves, we further overlaid percentile lines that can be used by clinicians to evaluate the neuromotor development of children

Détection de la fatigue neuromusculaire de l’épaule au moyen de la Théorie Cinématique des mouvements humains rapides

Les troubles musculo-squelettiques de l’épaule, et plus particulièrement ceux impactant la coiffe des rotateurs sont omniprésents dans notre société. Ils sont handicapants dans la vie de tous les jours et également très coûteux. Les coûts directs et indirects associés sont considérables. Il est alors important de les prévenir. Les causes de blessures à la coiffe des rotateurs sont multifactorielles. Parmi elles se trouve la fatigue musculaire, qui peut être soit centrale (du système nerveux central) ou périphérique (des muscles). Lors de mouvements répétitifs à hauteur d’épaule ou au-dessus de la tête, de la fatigue apparait, qui suite à une réaction en chaine peut entrainer une blessure. Les sportifs, dont les gestes impliquent de nombreuses répétitions de mouvement du bras, sont souvent sujets à des risques de blessures de l’épaule. Une façon de prévenir les blessures est alors d’étudier la fatigue musculaire à la coiffe des rotateurs. Ceci permettrait d’adapter à terme les entrainements pour chaque sportif et d’avoir un traitement personnalisé à chacun par des professionnels de la santé. Pour ce faire, un test clinique de détection de la fatigue doit être mis en place. Il doit être facile d’utilisation, peu coûteux et avec des données fiables, répétables d’un jour à l’autre et d’un évaluateur à l’autre. Cependant, à ce jour, il semble que les outils existants de détection de la fatigue musculaire à l’épaule peuvent difficilement être instaurés en clinique et différencier une fatigue centrale d’une fatigue périphérique. L’objectif de ce projet est d’innover dans les tests cliniques de détection de la fatigue de l’épaule. La Théorie Cinématique des mouvements humains rapides semble être une alternative efficace à l’étude du contrôle moteur. Il s’agit d’une méthode permettant de reconstruire le mouvement humain à partir de fonctions lognormales. Ses paramètres décrivent l’état physiologique du participant. Le dispositif expérimental constitué d’une tablette est ergonomique et peu coûteux. Les gestes à effectuer se rapprochent de l’écriture et sont faciles à exécuter, ce qui fait de cette méthode un bon candidat pour son utilisation en tant que test clinique. Pour ce faire, nous avons donc réalisé une première étude visant à étudier l’efficacité de détection de la fatigue neuromusculaire au moyen de la Théorie Cinématique. Vingt participants sains et sportifs ont réalisé deux séances avec une procédure similaire : exécuter des traits sur une tablette (traits simples, triangles, oscillations horizontales et oscillations verticales), fatiguer un muscle de l’épaule (le sous-scapulaire ou l’infra-épineux en fonction de la séance) et exécuter de nouveaux traits sur tablette. Des différences significatives avec taille d’effet de modérée à très large ont été constatées dans les paramètres de la théorie, suite aux deux séances. D’un point de vue théorique, il a été possible de différencier une fatigue centrale d’une fatigue périphérique. Un profil de réponse général suite à la fatigue a également été dénoté. Par ailleurs, un suivi de fatigue individualisé est également possible dans un souci d’accompagnement personnalisé. Tandis que le test des traits simples permettait de savoir plus facilement si la fatigue était centrale ou périphérique, le test des oscillations était le plus sensible. La différence de réaction suite au muscle fatigué n’a pas encore été établie. La deuxième étude visait à analyser la répétabilité des données d’un jour à l’autre. Pour cela, les mêmes traits que ceux exécutés pendant l’étude de la fatigue ont été réalisés par 40 participants deux fois à un jour d’intervalle minimum entre chaque séance. Une bonne répétabilité des données a été établie pour la plupart des paramètres des tests. Néanmoins, le changement minimal détectable était plus élevé que les différences avant et après fatigue de la première étude. Ceci nous amène à penser qu’il n’est à ce jour pas utilisable dans notre étude de cas. Afin de se conformer aux exigences d’un nouveau test clinique, il faudrait que des études de sensibilité et de spécificité soient entreprises afin de s’assurer de la bonne détection des personnes fatiguées. En dépit des limitations, l’utilisation de la Théorie Cinématique semble être une approche innovante pour détecter la fatigue neuromusculaire, et utilisable en clinique. Ces connaissances sont nécessaires afin de mieux guider les sportifs dans leur entrainement et éviter l’apparition à plus long terme de blessure.----------ABSTRACT Shoulder musculoskeletal disorders, and particularly those affecting the rotator cuff, are omnipresent in our society. They are incapacitating in the daily life and are also expensive. Direct and indirect costs associated with them are huge. Their prevention is therefore important. The causes of rotator cuff injuries are multifactorial. One of them is muscle fatigue, which can be either central (from the central nervous system) or peripheral (from the muscles). Fatigue appears when repetitive movements are made at shoulder height or overhead. As a result, it can lead to injuries. Sportsmen and women, whose movements involve many repetitive arm movements, are often at risk of shoulder injuries. Studying fatigue at the rotator cuff is a good way to prevent injuries. This would help in the long term to adapt training for each athlete and to have a personalized treatment for each one by health professionals. In that way, a clinical test to detect fatigue must be set up. It must be easy to use, inexpensive and with data that are reliable from one day/examiner to the other. However, to date, it appears that the existing tools for detecting shoulder muscle fatigue are difficult to implement in clinics and cannot easily differentiate between central and peripheral fatigue. The objective of this project is to innovate in clinical tests for the detection of shoulder fatigue. The Kinematic Theory of rapid human movement seems to be an effective alternative to study motor control. Human movement is reconstructed through lognormal functions. Their parameters describe the physiological state of the participant. The experimental device consisting of a tablet is ergonomic and inexpensive. The gestures to be performed are similar to writing and are easy to perform, making this method a good choice for clinical uses. We therefore carried out an initial study to investigate the effectiveness of detecting neuromuscular fatigue using the Kinematic Theory. Twenty healthy and active participants carried out two sessions with a similar procedure: performing strokes on a tablet (simple strokes, triangles, horizontal oscillations and vertical oscillations), fatiguing a shoulder muscle (subscapularis or infraspinatus depending on the session) and performing the strokes again on a tablet. Significant differences with moderate to good effect sizes were found in the parameters of the theory, following the two sessions. From a theoretical point of view it was possible to differentiate between central and peripheral fatigue. A general response profile to fatigue was also highlighted. In addition, an individualized fatigue follow-up is also possible. The distinction of the type of fatigue (central vs peripheral) is more easily detectable with the test of the simple strokes. The oscillation test was the most sensitive to fatigue. The difference in reaction to the fatigued muscle has not been established yet. The second study was designed to analyze the data reliability from one day to the other. For this purpose, the same strokes as those performed for the study of fatigue were performed twice with a minimum of one day interval between each session, by 40 participants. Good data reliability was ascertained for most of the parameters. Nevertheless, the minimal detectable change was greater than the pre- and post-fatigue differences in the first study. This leads us to believe that it is not usable yet in our case study. In order to comply with the requirements of a new clinical test, sensitivity and specificity studies would need to be undertaken to ensure the proper detection of fatigued participants. Despite some limitations, the use of the Kinematic Theory appears to be an innovative approach for detecting neuromuscular fatigue, that is clinically applicable. This knowledge is necessary to better guide athletes in their training and, in the long run, to avoid the occurrence of an injury