Il est estimé à 30 000 le nombre de paraplégiques et de tétraplégiques en France. On déplore environ 1 000 nouveaux cas tous les ans. La plupart résultent des accidents de la circulation, suivi de près par les accidents du travail et du sport. Les progrès scientifiques menés dans le cadre de la restauration des fonctions motrices déficientes ont été très importants durant ces dernières années. Une voie émergeante est l’utilisation de la stimulation électrique fonctionnelle. Le principe est de stimuler les membres déficients via des impulsions électriques, très brèves, transmises par des électrodes placées soit à la surface de la peau, soit à même le nerf moteur, permettant de déclencher artificiellement une contraction du muscle.

(далее…)

Категория: Научные статьи | Нет комментариев »

In this paper, we propose a device to assist persons with hemiparesis to walk by reducing or eliminating the effects of gravity. The design of the device inclu-des the following features:1) it is passive, i.e., it does not include motors or actuators, but is only composed of links and springs; 2) it is safe and has a simple patient–machine interface to accommodate variability in geometry and inertia of the subjects. A number of methods have been proposed in the litera-ture to gravity-balance a machine. Here, we use a hybrid method to achieve gravity balancing of a human leg over its range of motion. In the hybrid method, a mechanism is used to first locate the center of mass of the human limb and the orthosis. Springs are then added so that the system is gravity-balanced in every configuration. For a quantitative evaluation of the performance of the device, electromyographic (EMG) data of the key muscles, involved in the motion of the leg, were collected and analyzed. Further experi-ments involving leg-raising and walking tasks were performed, where data from encoders and force-torque sensors were used to compute joint torques. These experiments were performed on five healthy subjects and a stroke patient. The results showed that the EMG activity from the rectus femoris and hamstring muscles with the device was reduced by 75%, during static hip and knee flexion, respectively. For leg-raising tasks, the average torque for static positioning was reduced by 66.8% at the hip joint and 47.3% at the knee joint; however, if we include the transient portion of the leg-raising task, the average torque at the hip was reduced by 61.3%, and at the knee was increased by 2.7% at the knee joints. In the walking experi-ment, there was a positive impact on the range of movement at the hip and knee joints, especially for the stroke patient: the range of movement increased by 45% at the hip joint and by 85% at the knee joint.We believe that this orthosis can be potentially used to design rehabilitation protocols for pa-tients with stroke. Index Terms—Gait rehabilitation, gravity balancing, inverse dynamics, passive ortho-sis, rehabili-tation robotics.

(далее…)

Категория: Научные статьи | Нет комментариев »

Exoskeleton robots are mechanical constructions attached to human body parts, containing actuators for influencing human motion. One important application area for exoskeletons is human motion support, for example, for disabled people, including rehabilitation training, and for force enhancement in healthy subjects. This paper surveys two exoskeleton systems developed in our laboratory. The first system is a lower-extremity exoskeleton with one actuated degree of freedom in the knee joint. This system was designed for motion support in disabled people. The second system is an exoskeleton for a human hand with 16 actuated joints, four for each finger. This hand exoskeleton will be used in rehabilitation training after hand surgeries. The application of EMG signals for motion control is presented. An overview of the design and control methods, and first experimental results for the leg exoskeleton are reported.

(далее…)

Категория: Научные статьи | Нет комментариев »

This paper introduces a novel type of actuator for force-reflection to haptic master interfaces. The actuator is based on a DC motor that is relocated from the mechanism joint by means of bowden cable transmissions. After an introduction and formulation of the project goals, the paper highlights some important bowden cable transmission characteristics that influence the design of the necessary hardware. Next, a hardware prototype is presented that has been built to analyze the transmis-sion characteristics of the bowden cable transmissions between actuator and robotic joint. The prototype was used next to investigate achievable actuator performance in force-feedback control with a slave. Results are presented, which show good performance and contact stability in a 4 channel control scheme. The actuator has low movement resistance in free motion and can reflect high torques during hard contact situations with a slave.

(далее…)

Категория: Научные статьи | Нет комментариев »

The design and development of a high-performance robotic device is a process with numerous competing factors. The mechanism weight and stiffness exist at opposite ends of the spectrum, the goal being to achieve the highest structural rigidity while maintaining the lowest segmental inertias. Contributing to these underlying requirements are factors such as the operational workspace, desired joint torques, motor placement, link design and cable selection. Since the device will operate in direct contact with humans, additional requirements emerge regarding comfort and safety of operation.

(далее…)

Категория: Научные статьи | Нет комментариев »