Direction des Relations Internationales (DRI)

Programme INRIA "Equipes Associées"
/ INRIA "Associate Teams" Programme

 

I. DEFINITION

 

_

 

1.    Scientific goals of the proposal

 

A) Overall Objectives

 

The motivation approach is the complementary research works of these teams. Indeed, a collaborative project should give an additional value to their research results. On one hand, the DEMAR Project Team has experience in Functional Electrical Stimulation to restore or modulate movements on spinal cord injured patients and post stroke patients. In both pathologies researches on assisted gait using FES (for paraplegics with a walker and hemiplegics) are carried out in the team (cf. Figure 1).

 

 

 

          

Figure 1: (a) Paraplegic patient walking under FES, (b) Implanted FES stimulator

 

On the other hand, the Robotics research group (Stanford) carries out manipulation tasks with a humanoid robot under equilibrium constraints  (cf. Figure 2).

 

 

 

 

 

       

 

Figure 2: Motion analysis on SAI

 

B) Collaborative projects

 

Within the framework of the previous collaboration, the crossed visits and seminars last year led us to work on two different directions:

-  FES muscle modeling in Opensim framework

- Control mechanisms underlying age-related changes in motor control strategies during Sit-To-Stand.

 

We describe briefly each of them and make a conclusion on the topics we want to focus our efforts next year.

 

 

2. Review of 2010

 

A) FES muscle modeling in opensim framework  

(M. Hayashibe, D. Guiraud, L. Sentis, E. Demircan, O. Khatib)

In FES, movement synthesis and control are still challenging task due to the complexity of whole body dynamics computation and the nonlinearity of stimulated muscle dynamics. The characteristics of each muscle and each patient are quite different then mathematical model to represent the muscle dynamics and whole body biomechanics system should be required to enable the identification and the control corresponding to the subject-specific modeling. An efficient movement synthesis means that criteria can be defined and evaluated through an accurate numeric simulation. Optimization methods are then used to process the data in order to obtain stimulation patterns for a given movement.

For the first step of the above objective, we have performed the implementation of muscle model representing the electrically stimulated muscle into the Stanford opensim framework which has whole body musculoskeletal geometry.  Initially, our FES physiological muscle model was developed in matlab. For the integration with Stanford platform for whole body dynamic computation, it was essential to be rewritten in c++ class and in opensim structure. SAI dynamics platform of Stanford side can be naturally compatible with the opensim muscle style code.

Fig.1 FES muscle activation test in simple dynamic situation with two muscles. The right plots show activation level, developed muscle force and the contracted muscle length respectively.

The FES muscle class was implemented and integrated with the opensim platform. FES muscle activation was tested in simple dynamic situation with two muscles as shown in Fig.1. Blue lines show the path of muscle and the gray block was fixed on the floor then middle cube was pulled with the identical muscle stimulated synchronously. The right plots show activation level, developed muscle force and the contracted muscle length respectively. The result in this isometric test showed the same result as the numerical integration in matlab.

The implementation of FES muscle class allows us to easily develop the plug-in to be used with whole body musuculoskeletal model. Originally opensim model is embedded with Hill muscle model designed to represent voluntary muscle contractions. Through plug-in feature in opensim environment, all muscles could be replaced with FES muscle models as shown in Fig.2.

Fig.2 Musculoskeletal model with FES muscle models in opensim platform.

For the next year, we should work on the simulation to reproduce experimental motion data and the control in SAI dynamic environment. Implementation of muscle class should be improved to be utilized for the optimization to find appropriate stimulation input signals. If the desired task is given, inverse kinematics and dynamics should be able to be solved. It already can be done at least in joint dynamics level. However, automatic generation of stimulation signals in FES considering whole body dynamics and muscle redundancy is not yet solved. Then, we can enter the step for next year. The optimization or control criteria would be required to solve muscle redundancy problem. Using experimental motion data, and trying to find the appropriate FES signals for different criteria can be interesting for the advanced FES controller development.

 

B) The HumanPost project: motion control in the elderly population.

(E. Demircan, O. Khatib, P. Fraisse, M. Vanoncini, T.Keller (Fatronik))

 

HumanPost is joint research project involving the Lirmm the Research Centre Fatronik-Technalia (with main headquarters in San Sebastian, Spain, and a “node” in Montpellier, France) and Stanford University through @Walk project. The visit to Stanford first was participating to a workshop on the software package Opensim; the second was to establish a working relationship with Emel Demircan, a PhD student at the AI laboratory. Both objectives are closely related to the HumanPost project, as explained later in this document (see sections “Opensim workshop” and “EMG informed CMC project”).

 

The aim of the Humanpost project is to study motion control in the elderly population, and in particular during sit-to-stand transfers. The ageing process induces physiological changes which have detrimental effects on postural coordination and stability control; understanding and modelling such effects has potential impact on clinical practice and humanoid robotics. In clinical practice, such knowledge can lead to the development of more reliable testing procedures for fall prevention in the elderly population, and allow the development of more effective post-traumatic rehabilitation procedures. In humanoid robotics, it will guide the development of better human-machine interfaces for robotic devices aimed at providing mobility assistance for the frail eldelry during daily activities, possibly interacting with their carers. Following this vision, the project focuses on the Sit-To-Stand (STS) transfer, since it is a pre-requisite for independent living, and is at the base of several test procedures used in clinical practice. The experimental work conducted for the project consisted in collecting biomechanical data (movement, forces exerted on the ground, and muscle electrical activity) during STS transfers performed by a total of 37 volunteers, divided in 2 age groups (young and elderly). Each volunteer was asked to perform STS movements at different velocities and with eyes open or closed; imposing more challenging conditions than those encountered in everyday activities was expected to magnify differences between the two age groups in the movement strategies adopted.

 

The software Opensim was used to perform several steps of the data elaboration procedure, to compute meaningful variables for a comparison of the STS in the two age groups. The workshop organized at Stanford University was allowed us to improve our usage of this software tool.

 

The Opensim workshop

Opensim is a free-to-the-user software package for the simulation of the human body, providing tools for the elaboration of typical sets of experimental data collected in movement laboratories. The software is developed and maintained at the Simbios National NIH Center for Biomedical Computing, based at Stanford University, and it is being adopted as a working tool by a growing community of research scientists all over the world. The workshop organized in Stanford brought together users from different research institutions, and focused on the particular applications proposed by the participants. We consider the participation to the workshop as an invaluable experience, since it allowed us to deepen our knowledge of the software by talking directly to the developers. This enhanced our awareness of its potentialities and of its limitations, which is essential for a critical analysis of the results of my study. We are using Opensim to compute the values of the physiological joint angles of the human body (ankle, knee, hip, etc) from the data collected with a motion capture system; furthermore, it allows to compute the joint torques needed to accomplish the STS movement, and to estimate the muscle contractions required to produce such torques. However, the estimate is based on mechanical models of the biological tissues (tendons,ligaments and muscles) which have only been validated for a population of young adults. This may limit the results currently obtainable from experimental data collected on the elderly population. The EMG informed CMC project tries to address this issue.

 

The EMG informed CMC project

The EMG informed CMC project aims at using electromyographic signals (EMG) as an additional source of information for the estimation of the muscle control activations (Computed Muscle Control), which are currently estimated on the basis of measured movement and force exerted on the ground. The new concept has been implemented as a software plug-in for Opensim by Emel Demircan (Stanford University), and has been tested on a limited set of experimental data, collected during a walking cycle. The EMG informed CMC project aims at validating and improving the new tool, by testing it on the data collected during STS movements. Our visit to Stanford gave us the opportunity to work with E. Demircan the specific aims of the project, and to plan the research work. It is envisaged that the improved estimation of the muscle activations provided by the new software will serve as a tool for a more appropriate comparison of young and elderly subjects than what is possible at the present time.

In fact, the modifications of the musculoskeletal system due to ageing (decrease in force and velocity of contraction of the myofibers, changes in the mechanical properties of the tendons, etc.) have been widely investigated and measured for specific cases (e.g. flexion/extension of the ankle joint). However, a generalization of this work of quantification remains difficult, and hence it is impossible to include age related modifications in a full body model of the human body. Therefore, biomechanical studies in gerontotechnology are usually conducted considering a model validated for the young population. This may induce a bias in the results, typically in the estimation of the muscle activations required to perform a chosen movement. The EMG informed CMC project proposes a method to improve the estimation of muscle activations which takes into account the effects of the ageing process, since these are reflected by the EMG recordings. The research will not involve the development of a model of the elderly, which would require more time and resources; nonetheless it will allow to estimate the error which is committed when using a « young model » to estimate muscle activations in the elderly. This information will allow to judge the urgency of the development of biomechanical model for the elderly.

 

 

C) Common Publications in 2010

 

Journals

 

M. Vanoncini, E. Demircan, P. Fraisse, N. Ramdani, T. Keller, O. Khatib, Control mechanisms underlying age-related changes in motor control strategies during Sit-To-Stand. Submitted to Gait & Posture.

 

- We are also preparing a paper on Sit-to-Stand modeling in collaboration with Stanford for Journal of Biomechanics. We aim at developing a simulation tool based on an optimization process dedicated to elderly people for physiotherapy exercises.

 

Workshop

Pr. O. Khatib has organized a workshop entitled “Musculoskeletal Biomechanics, Model and Simulation” at the International Conference & Course on Orthopaedic Biomechanics, Clinical Applications & Surgery, June 2010, London, England.

 

The papers presented are:

 

1) M.Vanoncini, N.Ramdani, P.Fraisse and T.Keller, COP and COM Control during STS: Effects of Ageing.

2) E. Demircan, O. Khatib, Robotics-Based Human Dynamic Performance Analysis

3) M. Hayashibe, Q. Zhang, D. Guiraud, C. Fattal (Clique Propara), P. Fraisse, Modeling and Experimental Identification for Muscular Force Estimation Based on Evoked EMG in FES

 

 

Report on HumanPost project.

 

Exchanges 2010

 

Stanford:

- Emel Demircan, 2,5 weeks (June/July 2010)

- Luis Sentis, 1 week (June 2010)

- O. Khatib, 1 week (October 2010)

 

Demar Project:

- Mitsuhiro Hayashibe, 3 weeks (April/May 2010)

- Michele Vanoncini, 3 weeks (April/may 2010)

- P. Fraisse, 4 weeks (August/September 2010)

 

2. Review of 2011

A) FES muscle modeling in opensim framework

In FES, movement synthesis and control are still challenging tasks due to the complexity of whole body dynamics computation and the nonlinearity of stimulated muscle dynamics. An efficient movement synthesis means that criteria can be defined and evaluated through an accurate numeric simulation. We perform the implementation of muscle model representing the electrically stimulated muscle into the OpenSim framework which has whole body musculoskeletal geometry. We would like to develop the FES simulator using Stanford Operational Space Whole-Body Controller which allows the real-time motion generation with virtual FES and finally we aim at the development of motion correction controller to find the appropriate FES signals against a disabled motor function.

 

B) The HumanPost project: motion control in the elderly population.

HumanPost is joint research project involving the Lirmm the Research Centre Fatronik-Technalia (with main headquarters in San Sebastian, Spain, and a “node” in Montpellier, France) and Stanford University through @Walk project. The visit to Stanford first was participating to a workshop on the software package Opensim; the second was to establish a working relationship with Emel Demircan, a PhD student at the AI laboratory. Both objectives are closely related to the HumanPost project, as explained later in this document (see sections “Opensim workshop” and “EMG informed CMC project”).

 

The aim of the Humanpost project is to study motion control in the elderly population, and in particular during sit-to-stand transfers. The ageing process induces physiological changes which have detrimental effects on postural coordination and stability control; understanding and modelling such effects has potential impact on clinical practice and humanoid robotics. In clinical practice, such knowledge can lead to the development of more reliable testing procedures for fall prevention in the elderly population, and allow the development of more effective post-traumatic rehabilitation procedures. In humanoid robotics, it will guide the development of better human-machine interfaces for robotic devices aimed at providing mobility assistance for the frail eldelry during daily activities, possibly interacting with their carers. Following this vision, the project focuses on the Sit-To-Stand (STS) transfer, since it is a pre-requisite for independent living, and is at the base of several test procedures used in clinical practice. The experimental work conducted for the project consisted in collecting biomechanical data (movement, forces exerted on the ground, and muscle electrical activity) during STS transfers performed by a total of 37 volunteers, divided in 2 age groups (young and elderly). Each volunteer was asked to perform STS movements at different velocities and with eyes open or closed; imposing more challenging conditions than those encountered in everyday activities was expected to magnify differences between the two age groups in the movement strategies adopted.

 

The software Opensim was used to perform several steps of the data elaboration procedure, to compute meaningful variables for a comparison of the STS in the two age groups. The workshop organized at Stanford University was allowed us to improve our usage of this software tool.

 

The EMG informed CMC project

The EMG informed CMC project aims at using electromyographic signals (EMG) as an additional source of information for the estimation of the muscle control activations (Computed Muscle Control), which are currently estimated on the basis of measured movement and force exerted on the ground. The new concept has been implemented as a software plug-in for Opensim by Emel Demircan (Stanford University), and has been tested on a limited set of experimental data, collected during a walking cycle. The EMG informed CMC project aims at validating and improving the new tool, by testing it on the data collected during STS movements. Our visit to Stanford gave us the opportunity to work with E. Demircan the specific aims of the project, and to plan the research work. It is envisaged that the improved estimation of the muscle activations provided by the new software will serve as a tool for a more appropriate comparison of young and elderly subjects than what is possible at the present time.

 

In fact, the modifications of the musculoskeletal system due to ageing (decrease in force and velocity of contraction of the myofibers, changes in the mechanical properties of the tendons, etc.) have been widely investigated and measured for specific cases (e.g. flexion/extension of the ankle joint). However, a generalization of this work of quantification remains difficult, and hence it is impossible to include age related modifications in a full body model of the human body. Therefore, biomechanical studies in gerontotechnology are usually conducted considering a model validated for the young population. This may induce a bias in the results, typically in the estimation of the muscle activations required to perform a chosen movement. The EMG informed CMC project proposes a method to improve the estimation of muscle activations which takes into account the effects of the ageing process, since these are reflected by the EMG recordings. The research will not involve the development of a model of the elderly, which would require more time and resources; nonetheless it will allow to estimate the error which is committed when using a «young model» to estimate muscle activations in the elderly. This information will allow to judge the urgency of the development of biomechanical model for the elderly.

 

C) Common Publications/Contributions in 2011

 

Journal

Estimation of the centre of mass from motion capture and force plate recordings: a study on the elderly, by S. Cotton, M.Vanoncini, P.

Fraisse, N. Ramdani, E.Demircan, A.P.Murray & T.Keller, published by Applied Bionics and Biomechanics, February 2011, Volume 8, Issue 1,  Pages 67-84.

 

Workshop

 

1.CITRIS/INRIA Joint Workshop for Berkeley -- INRIA -- Stanford
Partnership Program, May 23 -- 24, 2011
Professor Oussama Khatib presented about Human Centered Robotics.
https://idal-siege.inria.fr/dri/bis2011/

2.Workshop on Robotics for Neurology and Rehabilitation, September 30th,
2011, IROS, San Francisco, California
Organizers: Professor Philippe Fraisse (LIRMM, France), Professor Gentiane
Venture (TUAT, Japan), Dr. Thierry Keller (Fatronik - Tecnalia, Spain),
Dr. Mitsuhiro Hayashibe (INRIA-LIRMM, France)
http://www.tuat.ac.jp/~venture/iros/index.htm

Professor Philippe Fraisse (LIRMM, France) made introductive and closing
remarks.
Emel Demircan (Stanford University, USA) presented about Task-Level
Reconstruction and Analysis of Dynamic Motions in Human Musculoskeletal
Systems.
Mitsuhiro Hayashibe (INRIA-LIRMM, France) presented about Modelling and
Identification of Neuromuscular Dynamics toward Advanced Neuroprosthetics.

This workshop was organized in IEEE IROS conference which was organized
by Professor Oussama Khatib as General Chair.

 

3. A talk given by Emel Demircan during the Journee Scientifique DEMAR, Universite de Montpellier 2, June 2011.

Title: “Reconstruction and Analysis of Task-Driven Dynamic Motions in Human Musculoskeletal Systems”.

 

D) Exchanges 2011

 

Stanford:

- Emel Demircan, 2 weeks (June/July 2011)

 

Demar Project:

- Mitsuhiro Hayashibe, 1 week (September 2011)

- P. Fraisse, 4 weeks (September/October 2011)

 

3. Previsions for 2012

 

A common publication for the Journal of Biomechanics on the development of FES muscle model for real-time whole-body motion/posture control.

A common publication for the IEEE EMBC 2012 on the development and the application of FES muscle model for real-time whole-body motion/posture control.

 

Exchanges for 2012:

 

Stanford:

- Emel Demircan (April 2012)

- Oussama Khatib (April 2012)

 

Demar Project:

-       M. Hayashibe (September 2012)

-       P. Fraisse (October 2012)

-       A. Gonzales (September 2012)

 

 

II. PREVISIONS 2012
/ 2012 Forecast

Programme de travail
Work programme

Description du programme scientifiquede travail (1 à 2 pages maximum)
/Description of the scientific work programme (maximum 1 to 2 pages)

 

Programme d'échanges avec budget prévisionnel
Exchanges schedule and estimated budget

1. Echanges / Exchanges

/ Describe the incoming and outgoing exchanges planned: invitations of researchers from the partner institution in France, and missions of INRIA researchers abroad:

 

Next year we plan the following agenda:

- 2012 April: visit of Pr. O. Khatib for 1 week, discussions, exchange.

- 2012 April: visit of Emel Demircan (PhD Student, Stanford University) to Montpellier for 2,5 weeks to work on identification and control.

- 2012 September: Visit of M. Hayashibe for 2,5 weeks to work on identification.

- 2012 September: visit of Alejandro Gonzales (PhD Student) for 2,5 weeks to work on control for paraplegic patient.

- 2012 October: visit of P. Fraisse for 1 week to work on control and to assess the collaboration as well as the future of the Demar-Stanford cooperation.

 

Résumez ensuite ces informations dans les tableaux 1 et 2 ci-dessous en faisant une estimation budgétaire:
/ Sum up the informations above in this two tables and indicate the estimated budget

1. ESTIMATION DES D_PENSES EN MISSIONS INRIA VERS LE PARTENAIRE Estimated spending for missions of INRIA researchers abroad	Nombre de personnes Number of persons	Coût estimé Estimated cost
Chercheurs confirmés Senior researcher	2	7ke
Post-doctorants Postdoctoral fellow
Doctorants PhD student	1	3ke
Stagiaires Intern	-
Autre (précisez) : Other (detail):	-
Total	4	10ke

 

2. ESTIMATION DES D_PENSES EN INVITATIONS DES PARTENAIRES Estimated spending for invitations of Partner researchers in France	Nombre de personnes Number of persons	Coût estimé Estimated cost
Chercheurs confirmés Senior researcher	1	3ke
Post-doctorants Postdoctoral fellow
Doctorants PhD student	1	3ke
Stagiaires Intern	-
Autre (précisez) : Other (detail):	-
Total	3	6ke

2. Cofinancement / Cofinancing

 

This collaboration is today only supported by INRIA. We plan to submit this year a proposal to get a co-financing support (ANR, PUF or NIH).

 

3. Demande budgétaire / Proposed budget

Indiquez, dans le tableau ci-dessous, le coût global estimé de votre projet et le budget demandé à la DRI dans le cadre de cette Equipe Associée (maximum 20 K€).

Avant de remplir le tableau, consultez les règles au paragraphe "Financement" de la page d'accueil du programme.

/ Fill in the table below with your project's global estimated budget (A), other sources of funding (B), and the contribution asked from INRIA International Affairs Department under the Associate Team Programme (A - B).
Please refer first to the funding conditions stated in the "funding" paragraph of the Associate Team programme presentation.

Commentaires	Montant
A. Coût global de la proposition (total des tableaux 1 et 2: invitations, missions, ...) A. Global cost of the collaboration project	16000€
B. Cofinancements utilisés (financements autres que Equipe Associée): from EADS project. B. Cofinancing (other than Associate Team program)	5000€
Financement "_quipe Associ_e" demand_ (A.-B.) Funding from the Associate Team programme (maximum 20 000 €)	11000€

 

 

_ INRIA - mise _ jour le 17/09/2009