Online Learning of the Dynamical Internal Model of Transfemoral Prosthesis for Enhancing Compliance

Powered prostheses hold promises to restore adaptive and robust locomotor functions to lower-limb amputees. However, their daily use is still challenged by several shortcomings, on top of which those related to their control methods. This paper reports the development of a compliant controller for a transfemoral prosthesis that combines an online predictive torque component with a feedback error correction mechanism. The controller architecture relies on joint position tracking. The predictive module is based on the Locally Weighted Projection Regression (LWPR) algorithm that achieves nonlinear function approximation of a dynamic model of the prosthesis joints. The performance of the proposed control strategy are assessed with a simulated biped walker with a unilateral transfemoral amputation. Results show that the LWPR-based module provides accurate predictions of the ankle and knee torques, resulting in a precise position tracking. This allows reducing the gains of the feedback error correction mechanism by one order of magnitude, leading to a feedback contribution to the total joint torque lower than 3\% and 8\% for the ankle and the knee joints respectively. The prosthesis compliance for both joints is enhanced accordingly. In addition, the control architecture is robust to speed changes while the joint dynamic internal model is continuously learned. This approach is thus promising for the development of adaptive controllers for lower-limb prostheses

Enhancing basic mathematical skills for freshmen

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Une “troisième voie"? entre approches qualitative et quantitative ?

Au terme de ce Forum, bien des questions restent ouvertes, à la fois au niveau plus fondamental de l’approche qu’au niveau plus concret de la technique et du travail empirique. Ces deux niveaux sont bien évidemment liés : les questions apparemment techniques, que ce soit dans l’AQQC ou les Ensembles Flous (EF), appellent souvent une réflexion plus fondamentale… et vice-versa. Notre propos sera tout d’abord de faire le point sur les atouts et limites de ces méthodes (principalement l’AQQC), et sur quelques enjeux plus profonds que certaines critiques soulèvent. Nous tenterons ensuite d’identifier les principaux chantiers qui sont en cours et encore à lancer, alors que ces méthodes suscitent une certaine effervescence

Torque control of an active elastic transfemoral prosthesis via quasi-static modelling

Developing mechanical devices to restore natural locomotion for transfemoral amputees still raises many challenges. One of them is the development of an efficient control strategy for the prosthesis active joints, with the objective of making it flexible and intuitive to use. This paper focuses on the transfemoral CYBERLEGs Beta-Prosthesis, an actuated elastic ankle–knee prosthesis embedding bio-inspired mechanisms targeting the minimization of its total power consumption. We provide the development of a bio-inspired, torque-based, controller for this device, requiring no torque sensing. Torque control is achieved by means of static modelling of the prosthesis geometrical and elastic relationships. Bench testing of the prosthesis was performed to show that this static model is able to accurately predict the actual behaviour of the device. The model was then used to build the low-level controller of the prosthesis, converting desired torques into reference positions for the joint actuators. Next, a walking experiment with a transfemoral amputee was conducted to assess the feasibility of a torque-based control approach for the prosthesis, with a simple high-level controller combining reference torque trajectories and bio-inspired joint impedances. Results validated the use of our static model for implementing the low-level controller of such an elastic and redundant prosthesis

Compliant Control of a Transfemoral Prosthesis Combining Predictive Learning and Primitive-Based Reference Trajectories

This paper reports the development of a novel compliant controller for a transfemoral prosthesis that combines a feed-forward prediction torque component with a feedback error correction. The controller architecture aims to track primitive-based reference trajectories by the prosthetic joints. It relies on Locally Weighted Projection Regression, a function approximator that acts as an inverse internal model of the prosthesis. The proposed strategy is validated in a simulation environment

De mondiale economie : regulering doorheen conflicten ? Nieuwe vormen van samenwerking tussen ondernemingen en nieuwe sociale bewegingen

Dit rapport presenteert de resultaten van een onderzoek over conflicten en samenwerkingsverbanden tussen enerzijds sociale bewegingen en anderzijds private ondernemingen.Dataverzameling leverde eerst een breed overzicht van de incidentie van conflicten en samenwerking tussen deze groepen. Vervolgens werden enkele sectoren geselecteerd voor een meer gedetailleerde analyse, met name de textiel - en geneesmiddelenindustrie, de consumptiegoerderen - en voedingsindustrie, de distributie en kleinhandel, de hout en visserij en de petroleumsector. De onderzoeksresultaten tonen aan dat belangrijke conflicten in elk van deze sectoren voorkomen, terwijl slechts in enkele sectoren betekenisvolle samenwerkingsverbanden ontstaan. Ondernemingen in die laatste sectoren zien een toegevoegde waarde in vergaande partnerschappen met sociale bewegingen, terwijl andere ondernemingen externe aanklachten eerder proberen te ontwijken of te neutraliseren

Quasi-Static Modelling of a Redundant Knee Prosthesis

Developing mechanical devices to restore natural locomotion for transfemoral amputees still raises many challenges. One of them is the development of an efficient control strategy for the prosthesis active joints, with the objective of making it flexible and intuitive to use. This paper reports the modelling of the knee joint of the transfemoral CYBERLEGs Beta-Prosthesis, an actuated elastic ankle-knee prosthesis designed with the objective to minimize its total power consumption. More precisely, we report the static model of the prosthetic knee that was used to build its low-level controller, converting the desired torque into a reference position for the joint actuator. Bench testing of the prosthetic knee was performed to show that this static model is able to accurately predict the actual behaviour of the device

Comparison of solidification/stabilization of fly ash and air pollution control residues from municipal solid waste incinerators with and without cement addition

© 2014, Springer Japan. Solidification/stabilization (S/S) of fly ash and air pollution control residues from MSWI was studied, with and without the use of cement. It appeared that metal and oxyanion leaching from these stabilised residues was comparable after 75 days of curing. Leaching of chloride and sulfate did not decrease by the addition of cement during S/S treatment. In an LCA perspective the environmental impact of the S/S treated mixtures with cement in the toxicity related impact categories was higher than the impact of the S/S treated mixtures without cement. Moreover, the production of cement for application in S/S also causes an impact in the impact categories climate change and terrestrial acidification. For environmental considerations in an LCA perspective S/S without cement should be preferred.status: publishe