Solving dynamical systems in neuromorphic hardware: simulation studies using balanced spiking networks

International audienc

Functional Rehabilitation: Coordination of Artificial and Natural Controllers

International audienceWalking and standing abilities, though important for quality of life and participation in social and economic activities, can be adversely affected by central nervous system (CNS) disorders such as spinal cord injury, stroke or traumatic brain injury. One characteristic of motor deficiencies which affect lower extremities is their impact on both static and dynamic postural equilibrium. Depending on the impairment level, functional rehabilitation techniques may be needed for a patient to stand up and walk (Popovic and Sinkjær, 2003). Functional electrical stimulation (FES) can induce contraction of skeletal muscles by applying electrical stimuli to sensory-motor system via electrodes which can be placed on the skin (Kralj et al., 1983), or implanted (Guiraud et al., 2006). FES applications applied to lower limbs include foot drop correction, single joint control, cycling, standing up, walking... (Zhang and Zhu, 2007)..

Posture and Movement Estimation Based on Reduced Information. Application to the Context of FES-based Control of Lower-Limbs

International audienc

Restauration fonctionnelle de la posture et de la marche : vers la coordination des membres valides et déficients

Ces travaux s'inscrivent dans le cadre de la restauration fonctionnelle du mouvement des membres inférieurs. Plus précisément, nous nous intéressons au problème de la cohabitation entre les mouvements volontaires et les mouvements contrôlés artificiellement par des techniques telles que l'électro-stimulation fonctionnelle. Nous proposons dans cette thèse d'observer le mouvement des membres valides à l'aide de micro-capteurs embarqués pour améliorer le contrôle des membres déficients chez les patients handicapés. Deux niveaux de coordination sont introduits : un niveau stratégique, où l'on cherche à identifier au plus tôt le mouvement que le patient souhaite effectuer, et un niveau tactique, où l'on cherche à estimer des paramètres du mouvement en cours de réalisation. Notamment, pour assurer la coordination des deux jambes durant la marche, le concept de CPG (Central Pattern Generator) est introduit, et nous proposons une méthode robuste de détection de phase basée sur l'observateur d'un oscillateur non-linéaire. Ce cadre de travail mélange des comportements discrets et continus, et implique la mise en place d'une architecture de commande hybride permettant l'intégration de ces deux aspects. Deux contraintes fortes sont la réduction du nombre de capteurs, et la faible complexité des algorithmes. Les solutions proposées font appel à des modèles des mouvements observés, et ont été validées par des expérimentations temps-réel.When controlling postural movements through artificial prosthetic limbs or Functional Electrical Stimulation, an important issue is the enhancement of the interaction of the patient with the artificial system through his valid limb motions. We address the problem of the coexistence of voluntary controlled with artificially controlled movements. We propose to observe the valid limbs through movement sensors in order to optimize the interaction at two levels: a strategic level, where we aim at identifying as soon as possible the postural task the patient intends to execute, and a tactic level, where we aim at monitoring the ongoing task in order to estimate some movement parameters. Particularly, to ensure legs coordination during walking, the CPG (Central Pattern Generator) concept is introduced, and we propose a robust phase estimation method based on the observer of a non-linear oscillator. This framework mixes discrete and continuous behaviors; this duality raises some integration issues and implies to setup a hybrid command architecture. Two additional constraints are the required number of sensors, as well as the complexity of the algorithms, that both have to be kept as low as possible.GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

Decentralized Optimization of Energy Exchanges in an Electricity Microgrid

International audienceIncreasing costs of energy, proliferation of electrical appliances, and climate change are major drivers that are reshaping the power generation, distribution, and usage landscape

Continuous identification of gait phase for robotics and rehabilitation using microsensors

International audienceUsing microsensors for the robust and accurate analysis of human posture or gait is an interesting opportunity for rehabilitation and robotics applications. This paper describes a feasibility study in which the possibility of using a new type of embedded microsensors, based on the coupling of accelerometers and magnetometers, and developed by CEA/LETI is investigated. This study consists in identifying what part of the gait cycle is active by using a reconstruction of the knee joint angle by two microsensors fixed on tibia and thigh, during a steady- state sagittal walk. More than just an identification of a few gait states, this approach allows us to continuously extract the current position on the gait cycle. We compare the reconstructed knee joint angle with a stored reference taking into account uncertainties on the velocity and perturbations of the terrestrial magnetic field. To accurately identify the phase of the gait movement, we fuse different simple and complementary meth- ods: morphomathematics, cyclogram analysis, wavelet transform, qualitative analysis, crosscorrelation. These results encourage us to extend this work to explore the possibility of recognition of a larger set of human movements using more sensors and improved algorithms of signal processing