Nicolas Vignais

Université de Rennes 2 | UR2 · Laboratory for Movement, Sport, Health

Workers involved in hospital operating room cleaning face numerous constraints that may lead to musculoskeletal disorders. This study aimed to perform physical ergonomic assessments on hospital staff by combining a continuous assessment (RULA) based on inertial measurement units with video coding. Eight participants performed cleaning tasks while w...

Active upper limb exoskeletons are a potentially powerful tool for neuromotor rehabilitation. This potential depends on several basic control modes, one of them being transparency. In this control mode, the exoskeleton must follow the human movement without altering it, which theoretically implies null interaction efforts. Reaching high, albeit imp...

In the field of robotic exoskeleton control, it is critical to accurately predict the intention of the user. While surface electromyography (EMG) holds the potential for such precision, current limitations arise from the absence of robust EMG-to-torque model calibration procedures and a universally accepted model. This paper introduces a practical...

In this paper, we consider an industrial exoskeleton called ABLE, which we controlled using an adaptive oscillator. In the context of periodic human movements around the elbow axis we show that the exoskeleton anticipates smoothly the human movement, converges towards a limit cycle, and is "robust" against non-deterministic bounded perturbations. I...

Gravity is a ubiquitous component of our environment that we have learned to optimally integrate in movement control. Yet, altered gravity conditions arise in numerous applications from space exploration to rehabilitation, thereby pressing the sensorimotor system to adapt. Here, we used a robotic exoskeleton to reproduce the elbow joint-level effec...

Time and effort are thought to be subjectively balanced during the planning of goal-directed actions, thereby setting the vigor of volitional movements. Theoretical models predicted that the value of time should then amount to high levels of effort. However, the time-effort trade-off has so far only been studied for a narrow range of efforts. To in...

The purpose of this study was to compare electromyographic (EMG) with mechanomyographic (MMG) recordings during isometric conditions, and during a simulated load-lifting task. Twenty-two males (age: 25.5 ± 5.3 years) first performed maximal voluntary contractions (MVC) and submaximal isometric contractions of upper limb muscles at 25%, 50% and 75%...

The purpose of this study was to compare Electromyographic (EMG) with Mechanomyo- 1 graphic (MMG) recordings during isometric conditions, and during a simulated load-lifting task. 2 Twenty-two males (age: 25.5 ± 5.3 years) first performed maximal voluntary contractions (MVC) and 3 submaximal isometric contractions of upper limb muscles at 25%, 50%...

Exoskeletons are among the most promising devices dedicated to assisting human movement during reeducation protocols and preventing musculoskeletal disorders at work. However, their potential is currently limited, partially because of a fundamental contradiction impacting their design. Indeed, increasing the interaction quality often requires the i...

Time and effort are critical factors that are thought to be subjectively balanced during the planning of goal-directed actions, thereby setting the vigor of volitional movements. Theoretical models predicted that the value of time should then amount to relatively high levels of effort. However, the time-effort tradeoff has so far only been studied...

(1) Background: Healthcare workers are highly affected by work-related musculoskeletal disorders, particularly in the lower back, neck and shoulders, as their occupational tasks expose them to biomechanical constraints. One solution to prevent these musculoskeletal disorders may be the use of a passive exoskeleton as it aims to reduce muscle solici...

Kinematics obtained using Inertial Measurement Units (IMUs) still present significant differences when compared to those obtained using optoelectronic systems. Multibody Optimization (MBO) might diminish these differences by reducing soft-tissue artefacts - probably emphasized when using IMUs - as established for optoelectronic-based kinematics. To...

Gravity is a ubiquitous component of our environment that we learnt to optimally integrate in movement control. Yet, altered gravity conditions arise in numerous applications from space exploration to rehabilitation, thereby pressing the sensorimotor system to adapt. Here, we used a robotic exoskeleton to test whether humans can quickly reoptimize...

Ground reaction forces (GRF) have been widely studied in football to prevent injury. However, ambulatory tools are missing, posing methodological limitations. The purpose of this study was to assess the validity of an innovative football shoe measuring normal GRF (nGRF) directly on the field through instrumented studs. A laboratory-based experiment...

Active exoskeletons are promising devices for improving rehabilitation procedures in patients and preventing musculoskeletal disorders in workers. In particular, exoskeletons implementing human limb’s weight support are interesting to restore some mobility in patients with muscle weakness and help in occupational load carrying tasks. The present st...

Despite exoskeletons becoming widespread tools in industrial applications, the impact of the design of human–exoskeleton physical interfaces has received little attention. This study aims at thoroughly quantifying the influence of different physical human–exoskeleton interfaces on subjective and objective biomechanical parameters. To this aim, 18 p...

Chronic Low Back Pain (cLBP) is not a pathology but a symptom. Patients with cLBP constitute a heterogeneous population. Some patients with cLBP increase trunk muscle activity as a “guarding strategy” [1]. Psychological subgrouping scheme based on multiple Fear-Avoidance Model has been proposed [1]. This model could be approach considering on...

Presentation made at the congress in connection with the abstract "Fear-Avoidance Belief Questionnaire, motor control and dynamic electromyography in case of patients with chronic Low Back Pain. A qualitative pilot study."

Implementing an intuitive control law for an upper-limb exoskeleton dedicated to force augmentation is a challenging issue in the field of human-robot collaboration. The goal of this study is to adapt an EMG-based control system to a user based on individual characteristics. To this aim, a method has been designed to tune the parameters of control...

Implementing an intuitive control law for an upperlimb exoskeleton dedicated to force augmentation is a challenging issue in the field of human-robot collaboration. The goal of this study is to adapt an EMG-based control system to a user based on individual characteristics. To this aim, a method has been designed to tune the parameters of control u...

Background Active exoskeletons are promising devices for improving rehabilitation procedures in patients. In particular, exoskeletons implementing human limb's weight support (WS) are interesting to restore some mobility in patients with muscle weakness. Using active exoskeletons should result in accurate and generic WS but its effect on human moto...

Active exoskeletons are promising devices for improving rehabilitation procedures in patients and preventing musculoskeletal disorders in workers. In particular, exoskeletons implementing human limb’s weight support are interesting to restore some mobility in patients with muscle weakness and help in occupational load carrying tasks. The present st...

Virtual reality platforms producing interactive and highly realistic characters are being used more and more as a research tool in social and affective neuroscience to better capture both the dynamics of emotion communication and the unintentional and automatic nature of emotional processes. While idle motion (i.e., non-communicative movements) is...

Exoskeletons are a solution to physically relieve workers while allowing them to control the execution of their tasks and assist them (Baltrusch et al.2018) . The study investigated in the search for elements able to quantify the action of a physical assistance device (PAD) on the human body for movements responsible for pathologies recognized as o...

Over the past decade, research on human–robot collaboration has grown exponentially, motivated by appealing applications to improve the daily life of patients/operators. A primary requirement in many applications is to implement highly “transparent” control laws to reduce the robot impact on human movement. This impact may be quantified through rel...

Background: A high level of sport practice may improve adaptive postural control specifically. Research question: The objective of this study was to examine how specific high-level sport practices may impact the static posture, especially the use of visual and plantar information. Methods: To this aim, postural performances have been compared bet...

Movement-based video games can provide engaging practice for repetitive therapeutic gestures towards improving manual ability in youth with cerebral palsy (CP). However, home-based gesture calibration and classification is needed to personalize therapy and ensure an optimal challenge point. Nineteen youth with CP controlled a video game during a 4-...

Implementing an intuitive control law for an upper-limb exoskeleton dedicated to force augmentation is a challenging issue in the field of human-robot collaboration. The aim of this study is to design an innovative approach to assist carrying an unknown load. The method is based on user's intentions estimated through a wireless EMG armband allowing...

Importance/Background Movement-controlled video games have potential to promote home-based practice of therapy activities. The success of therapy gaming interventions depends on the quality of the technology used and the presence of effective support structures. Aim This study assesses the feasibility of a novel intervention that combines a co-cre...

This article details the design of a co-created, evidence-based biofeedback therapy game addressing the research question: is the biofeedback implementation efficient, effective, and engaging for promoting quality movement during a therapy game focused on hand gestures? First, we engaged nine young people with Cerebral Palsy (CP) as design partners...

Implementing an intuitive control law for an upper-limb exoskeleton to perform force augmentation is a challenging issue in the field of human-robot collaboration. The aim of this study is to design an innovative approach to calibrate electromyography (EMG) data in order to detect the intention to lift or put down a charge while wearing an upper-li...

The purpose of this work was to assess the feasibility of using a head mounted display with a motion capture system to simulate real world occupational tasks. Participants performed a pointing task under 3 conditions: (1) real environment (REA), (2) virtual environment with auditory stimulus (VEA) and (3) virtual environment with visual stimulus (V...

Horseback riding requires the ability to adapt to changes in balance conditions, to maintain equilibrium on the horse and to prevent falls. Postural adaptation involves specific sensorimotor processes integrating visual information and somesthesic information. The objective of this study was to examine this multisensorial integration on postural co...

Dependent variables recorded through the force platform: Surface area covered by the CoP (mm2), Mean velocity of CoP (mm/s), VFY, Romberg Quotient of Surface area in different balance conditions: stable standing posture, unstable standing postures (AP seesaw and ML seesaw); and in different sensory conditions: Vision, No Vision, No Foam, Foam. (XLS...

Establishing a symbiotic relationship between a human and a exoskeleton is the end goal in many applications in order to provide benefits to the user. However, the literature focusing on the human side of human-exoskeleton interaction has remained less exhaustive than the literature focusing on the design (hardware/software) of the exoskeleton devi...

Introduction/Background Interactive computer play (ICP), or serious games, can provide motivational and flexible rehabilitation environments. This is useful for the 1 in 400 children born with Cerebral Palsy (CP) each year, whose daily activities are impacted by impaired motor control. Improvement through traditional rehabilitation is often hindere...

Introduction/Background Cerebral palsy (CP) is a neuromuscular condition affecting 1 in 400 children that limits activities of daily living. Essential elements to improving function are feedback and repetition. Feedback about a motor performance communicated back to the individual (e.g. biofeedback) can be a powerful tool for improving autonomy and...

Purpose: The purpose of this study is to evaluate the quality of evidence of biofeedback interventions aimed at improving motor activities in people with Cerebral Palsy (CP). Second, to describe the relationship between intervention outcomes and biofeedback characteristics. Methods: Eight databases were searched for rehabilitation interventions tha...

The aim of this study was to provide ergonomic recommendations concerning passenger compartment dimensions of an innovative vehicle dedicated to mail delivery. To this aim, an ergonomic analysis of egress/ingress postures has been performed on a physical mock-up, which is considered as a reliable tool when investigating driving space. Six workers w...

The aim of this study was to perform an ergonomic analysis of a material handling task by combining a subtask video analysis and a RULA computation, implemented continuously through a motion capture system combining inertial sensors and electrogoniometers. Five workers participated to the experiment. Seven inertial measurement units, placed on the...

Background: Cerebral palsy is a life-long disability that affects motor control and activities of daily living. Depending on the type of cerebral palsy, some individuals may have trouble performing tasks with one or both of their arms and/or legs. Different strategies exist to help develop motor capacity. Biofeedback therapy is a commonly applied...

Carpal tunnel syndrome is a neuropathy of the median nerve at the wrist, and represents the most common peripheral neuropathy. It has long been an issue in the workplace because of healthcare costs and loss of productivity. The two main pathomechanisms of carpal tunnel syndrome include increased hydrostatic pressure within the carpal tunnel (carpal...

Visual information uptake is a fundamental element of sports involving interceptive tasks. Several methodologies, like video and methods based on virtual environments, are currently employed to analyze visual perception during sport situations. Both techniques have advantages and drawbacks. The goal of this study is to determine which of these tech...

Assessing finger joint loading is essential to the prevention of work-related musculoskeletal disorders of the hand and fingers. This study aimed to evaluate the effect of muscle action on joint loading during dynamic finger pressing tasks using an open-source musculoskeletal modelling platform. Eight participants performed submaximal dynamic index...

Assessing finger joint loading is essential for the prevention of musculoskeletal disorders of the hand, wrist and forearm. Due to the technical and invasive nature of direct measurement, biomechanical modeling is necessary to evaluate finger joint forces. Most existing finger models have used maximum grip strength in order to quantify joint loads,...

This work presents a system that permits a real-time ergonomic assessment of manual tasks in an industrial environment. First, a biomechanical model of the upper body has been developed by using inertial sensors placed at different locations on the upper body. Based on this model, a computerized RULA ergonomic assessment was implemented to permit a...

The major goal of COGNITO was to develop enabling technologies for intelligent user assistance systems with focus on industrial manual tasks. This comprises technology for capturing user activity in relation to industrial workspaces through on-body sensors, algorithms for linking the captured information to underlying workflow patterns and adaptive...

In order to use virtual reality as a sport analysis tool, we need to be sure that an immersed athlete reacts realistically in a virtual environment. This has been validated for a real handball goalkeeper facing a virtual thrower. However we currently ignore which visual variables induce a realistic motor behaviour of the immersed handball goalkeepe...

Virtual reality has a number of advantages for analyzing sports interactions such as the standardization of experimental conditions, stereoscopic vision and complete control of animated humanoid movement. Nevertheless, in order to be useful for sports applications, accurate perception of simulated movement in the virtual sports environment is essen...

Improving performance in sports can be difficult because many biomechanical, physiological, and psychological factors come into play during competition. A better understanding of the perception-action loop employed by athletes is necessary. This requires isolating contributing factors to determine their role in player performance. Because of its in...

Contexte.– La main est notre organe de préhension qui permet la manipulation d’objets et d’outils. Sa gamme de manipulation est très variée allant d’une orientation millimétrique aux déplacements de masse de dizaines de kilos. De fait, la main est une structure anatomique complexe par la densité de structures osseuses, ligamentaires et musculaires....

Visual perception is a basic element allowing us to interact with our environment. During sport activities, the visual information uptake enable an athlete to extract and select visual cues necessary to anticipate the opposing action. In the field of sports, visual information uptake analysis has been widely carried out but all the methodologies us...