Computational Architecture of a Robot Coach for Physical Exercises in Kinesthetic Rehabilitation

International audienceThe rising number of the elderly incurs growing concern about healthcare, and in particular rehabilitation healthcare. Assistive technology and and assistive robotics in particular may help to improve this process. We develop a robot coach capable of demonstrating rehabilitation exercises to patients, watch a patient carry out the exercises and give him feedback so as to improve his performance and encourage him. We propose a general software architecture for our robot coach, which is based on imitation learning techniques using Gaussian Mixture Models. Our system is thus easily programmable by medical experts without specific robotics knowledge, as well as capable of personalised audio feedback to patients indicating useful information to improve on their physical rehabilitation exercise

Validity and reliability of 3D marker based scapular motion analysis : a systematic review

Methods based on cutaneous markers are the most popular for the recording of three dimensional scapular motion analysis. Numerous methods have been evaluated, each showing different levels of accuracy and reliability. The aim of this review was to report the metrological properties of 3D scapular kinematic measurements using cutaneous markers and to make recommendations based on metrological evidence. A database search was conducted using relevant keywords and inclusion/exclusion criteria in 5 databases. 19 articles were included and assessed using a quality score. Concurrent validity and reliability were analyzed for each method. Six different methods are reported in the literature, each based on different marker locations and post collection computations. The acromion marker cluster (AMC) method coupled with a calibration of the scapula with the arm at rest is the most studied method. Below 90–100° of humeral elevation, this method is accurate to about 5° during arm flexion and 7° during arm abduction compared to palpation (average of the 3 scapular rotation errors). Good to excellent within-session reliability and moderate to excellent between-session reliability have been reported. The AMC method can be improved using different or multiple calibrations. Other methods using different marker locations or more markers on the scapula blade have been described but are less accurate than AMC methods. Based on current metrological evidence we would recommend (1) the use of an AMC located at the junction of the scapular spine and the acromion, (2) the use of a single calibration at rest if the task does not reach 90° of humeral elevation, (3) the use of a second calibration (at 90° or 120° of humeral elevation), or multiple calibrations above 90° of humeral elevation

Proprioceptive postural control strategies differ among non-injured athletes

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Location of the best confident scapula cluster during a forward humeral elevation

Eleven subjects were equipped with a cluster of 120 markers on the scapula. Forward humeral elevation was then performed. Robust estimators are used in order to eliminate high deformation. Results underline the modification of the best cluster during elevation. Markers located on the lateral posterior part of the acromion were identified. They could be the best ones to measure dynamic scapula rotation during entire elevation

Robust local estimation in anisotropic diffusion process

International audienceIn this work we propose to use an anisotropic diffusion process using robust statistics. We show that smoothing, while preserving edges, helps the segmentation of upper limb bones (shoulder) in MRI data bases. The anisotropic diffusion equation is mainly controlled using an automatic edge stopping function based on Tukey's biweight function, which depends on the values of gradients pixels. These values are divided into two classes: high gradients for pixels belonging to edges or noisy pixels, low ones otherwise. This process also depends on a threshold gradient parameter which splits both former classes. So a robust local estimation method is proposed to better eliminate the noise in the image while preserving edges. Firstly, the efficiency of the model in the noise reduction is quantified using an entropy criterion on synthetic data with different noise levels to evaluate the smoothing of the regions. Secondly, we use the Pratt's Figure of Merit (FOM) method to evaluate edges preservation. Eventually, a qualitative edge evaluation is given on a MRI volume of the shoulder joint

Difference between palpation and optoelectronics recording of scapular

International audienceThe aim of this study is to determine the errors of scapular localisation due to skin relative to bone motion with an optoelectronic tracking system. We compared three-dimensional (3D) scapular positions obtained with skin markers to those obtained through palpation of three scapular anatomical landmarks. The scapular kinematics of nine subjects were collected. Static positions of the scapula were recorded with the right arm elevated at 0°, 40°, 80°, 120° and 160° in the sagittal plane. Palpation and subsequent digitisation of anatomical landmarks on scapula and thorax were done at the same positions. Scapular 3D orientation was also computed during 10 repeated movements of arm elevation between 0° and 180°. Significant differences in scapular kinematics were seen between static positions and palpation when considering anterior/posterior tilt and upward/downward rotation at angles over 120° of humeral elevation and only at 120° for internal/external rotation. There was no significant difference between positions computed during static positions and during the movement for the three scapular orientations. A rotation correction model is presented in order to reduce the errors between static position and palpation measurement

Radius movement simulation and evaluation based on articular surfaces

Radial bone movement, which is the main contributor of forearm prono-supination, has been suggested to occur around various axes, mobile or not, with respect to the humerus-ulna complex. The purpose of our study was to compare the results f rotation of the radius around a number of stationary axes

Etude des rapports articulaires de l'articulation du genou par analyse morpho-fonctionnelle

International audienceLes méthodes d'analyse de mouvements par capteurs externes sont les plus répandues pour obtenir les cinématiques des différentes articulations. Cependant, les courbes cinématiques ainsi obtenues sont entachées d'erreurs à cause notamment des artefacts liés aux tissus mous. Cela conduit donc à des dislocations ou des collisions plus ou moins importantes quand on les applique aux structures osseuses. C'est un challenge ouvert de consolider ces courbes cinématiques, et en particulier pour l'articulation du genou impliquée dans les études de la marche. La cinématique de flexion/extension du genou est classiquement modélisée par une rotation autour d'un axe statique. Cependant la tendance des études biomécaniques actuelles est d'améliorer cette modélisation en introduisant une connaissance morphologique comme des contraintes ligamentaires. Dans ce papier, nous proposons de mettre en évidence le lien morpho-fonctionnel de cette articulation grâce à deux contributions. La première consiste à proposer une méthode permettant d'extraire une cinématique de flexion/extension du genou à partir d'une seule acquisition 3D de la morphologie. Cette cinématique repose sur la détermination d'un axe mobile permettant la prise en compte des propriétés de roulement/glissement. La deuxième consiste en une analyse temporelle qualitative et quantitative des positions relatives des os dans l'articulation en mouvement. Pour cela, nous comparons les résultats obtenus pour les deux cinématiques (axe statique et mobile) à l'aide d'une Figure de Cohérence Articulaire originale et d'un indice associé

Quantitative study of knee joint surface configurations using a morpho-functional approach

International audienceWe propose a method that allows the extraction of flexion/extension kinematics of the knee from the 3D bones morphology obtained by segmentation of a single CT-scan acquisition. This method highlights the morpho-functional relationship in a joint and is based on the determination of a mobile axis accounting for the description of the rolling/sliding motion of the femur relative to the tibia. We will compare this simulated kinematics to flexion/extension kinematics obtained by direct measurements on a cadaver. This quantitative comparison is performed by proposing new figures and indices of joint coherence based on the previous works. The Figures and Index rely on the evoluting distances between articular surfaces during the motion. We use these tools to compare different surgeries of ACL reconstructions

Study of the joint configuration of the knee using a morpho-functional analysis

International audienceSkin marker motion analyses are the most widespread techniques to study human movements. Nevertheless, trajectories obtained through such methods are biased because of soft tissue artifacts and lead, consequently, to false collisions and dislocations when bone motion is under investigation. It's an open challenge to enhance kinematics curves particularly for the knee joint involved in the mechanics of gait. The kinematics of flexion/extension of the knee is classically modeled by a rotation around a fixed axis. However, the trend of current biomechanical studies is to improve this modeling by introducing a morphological knowledge such as ligament constraints. In this paper, we propose to highlight the morpho-functionnal link oh this joint thanks to two contributions. The first one consists in proposing a method capable of extract a kinematics of flexion/extension of the knee from a unique CT scan. This method is based on the determination of a mobile axis capable of keeping the information of rolling/sliding. The second one consists in a qualitative and quantitative temporal analysis of the position of the bones during the movement. . We compare the results of the two kinematics (static and mobile axis) using original figures of articular coherence and an associated index