Orthotics

Résumé

Orthotics (Ορθός) is a medical specialty that focuses on the design and application of orthoses, or braces. An is "an externally applied device used to influence the structural and functional characteristics of the neuromuscular and skeletal systems." Orthotists are professionals who specialize in designing these braces. Classification Orthotic devices are classified into four areas of the body according to the international classification system (ICS): orthotics of the lower extremities, orthotics of the upper extremities, orthotics for the trunk, and orthotics for the head. Orthoses are also classified by function: superdomis orthoses, common orthoses, and hard braces. Under the International Standard terminology, orthoses are classified by an acronym describing the anatomical joints they support. Some examples include: KAFO, or knee-ankle-foot orthoses, which span the knee, ankle, and foot; TLSO, or thoraco-lumbo-sacral ortho

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https://en.wikipedia.org/wiki/Orthotics

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The proportion of elderly people is rapidly growing and the resources to help them will soon be insufficient. An important difficulty faced by the seniors is locomotion. Among the conditions that may be responsible for gait impairment, the reduced muscular force is one of the most frequent in elderly. This thesis focuses on the design and the evaluation of new solutions for assisting people with reduced vigor. Robotic orthoses are then used to support critical movements required for walking. Over the last two decades, the use of actuated orthotic devices for helping people suffering from gait disorders has been made possible. Recently, autonomous devices have even enabled spinal cord injured patients to walk again by mobilizing their paralyzed limbs. Addressing a completely different population, similar devices have been developed to augment healthy users' capabilities, for instance when heavy loads need to be carried. In this case, the wearer is in charge of the movements and the device simply follows the imposed trajectories. Extra load can then be carried by the exoskeleton without being felt by the user. The walk assistive devices developed as part of this thesis being intended for the elderly, they are at the intersection between these two classes of robotic orthosis. Indeed, most of the seniors who have difficulties to walk are able to move and therefore the mobilization devices are not adapted to them. Even though they need assistance, they surely do not want to have their movements imposed by a robotic device. The performance augmentation exoskeletons cannot help them either, as they simply follow the movements and only reject the external perturbations. A device that follows their movements and that adds the right amount of force when needed is therefore required. In order to achieve the demanding characteristics associated with assistive devices, new actuation solutions based on conventional electric motors are proposed. The combination of specifications in terms of overall weight, required assistance torque, dynamics capabilities or transparency when no support is provided is undeniably challenging. Various mechanisms are therefore presented to address these requirements. Two prototypes based on the proposed solutions are presented. The first one is based on a ball-screw transmission combined with linkages which provides a transmission ratio that is adapted to multiple walk related activities. The second one uses a transmission with clutches and an inversion mechanism which notably limits the losses due to the inertia of the actuation and greatly improves the natural transparency. In order to limit the obstructiveness of the assistive device, we propose to use partial devices that support specific movements. Two studies about the influence of such partial devices on gait are therefore presented. The first one focuses on identifying the potential sources of gait disturbance that orthotic device can induce. The second examines the effects of an assistive controller implemented on one of the developed prototypes. These studies demonstrate that even though the passive influence of a hip assistive orthosis on kinematic patterns is limited, the metabolic cost is increased. A moderate assistance cannot compensate for this undesirable effect but a link between the hip assistance and the ankle trajectory could be established. This is of major importance as the elderly tend to compensate for their weak ankle muscles with their hips.

EPFL2016

Chargement

Système robotique pour la mobilisation des membres inférieurs d'une personne paraplégique

Patrick Métrailler

This thesis is the first to be carried out within the framework of the project "Cyberthosis for Paraplegics" in progress at the "Laboratoire de Systèmes Robotiques" (LSRO) of the "Ecole Polytechnique Fédérale de Lausanne" (EPFL). This project, initiated in 1999 by the "Fondation Suisse pour les Cyberthèses" in Villeneuve (FSC), is based on the reflections on the current means of physical rehabilitation of spinal cord injuries people. Eager to bring new methods of rehabilitation, the FSC initiated a program focused on the development of rehabilitation devices and overground walking assistance devices, associating an orthotic system with the electrical muscle stimulation. The main objective is to create an active muscular participation while preserving the physiological dynamic effects of the movements and thus to accelerate the process of rehabilitation. Three developments corresponding to three successive phases of rehabilitation are envisaged. A. MotionMaker™: stationary system for mobilization and muscular reinforcement. B. WalkTrainer™: mobile equipment allowing overground locomotion to stimulate neural plasticity and relearn walking. C. WalkMaker™: Assistance device for autonomous walking. The first stage of this thesis was to validate, on the knee joint, the closed loop control of electrically stimulated muscles with the information provided by an orthotic system. To do this, a robotic knee was designed. An electric motor controls the knee bending/extension, with resistance or assistance to the movement. Integrated sensors transmit, in real time, the values torques and articular positions to the dataprocessing programs which control the orthosis and the associated stimulator. This allows the adjustment of the resistance during movement and the adjustment of the electrical stimulation of the quadriceps muscles according to the kinematics and dynamics chosen. With this prototype we demonstrated the feasibility of closed loop control of electrically-stimulated muscles on able-bodied people as well as on people with spinal cord injuries. In a second stage, a more complete device, the MotionMaker™, was developed. It comprises two orthoses for the lower limbs. In the current state, the control unit allows the management of the 3 articulations (hip, knee and ankle) and of 7 muscles on each side (rectus femoris, vastus medialis and lateralis, gluteus maximus, semimembranosus and semitendinosus, tibialis anterior and gastrocnemius). Several algorithms of electrical stimulation control were proposed and evaluated in this thesis. They are either based on a mathematical model of the 7 muscles according to the stimulation current and the joint positions or on an iterative learning control. The development of this cyberthosis is currently sufficiently advanced to carry out, on able-bodied subjects, leg-press movements with control of the strength provided by the electrically-stimulated muscles. Thus the outcome push forces on the feet follow the values defined for the exercise. This work is focused on the movement of both above mentioned devices and on the model and the control of the electrical muscle stimulation. The mechanical parts have not been designed by the author.

EPFL2005

Chargement

Orthèses fonctionnelles à cinématique parallèle et sérielle pour la rééducation des membres inférieurs

Carl Schmitt

Robotics applied to rehabilitation requires specific manipulators: Powered Orthoses. They are orthopedic devices equipped with motors and captors that enable locomotor assistance. These powered orthoses must be capable of reproducing physiological articular trajectories and taking over or simulating the segmentary charges of a movement, mainly walking. One needs to obtain rather high dynamic performances with the help of small activators enabling mechanical integration bearable for its user. This doctoral thesis deals with the conception of such POs as well as it proposes original parallel kinematics that are compared with serial kinematics, i.e. ordinary exoskeletons. We have chosen to limit our study to motor re-education of lower limbs associated to neurological disorders: paratetraplegia, hemiplegia, cerebral palsy, etc. This project was initiated by the Fondation Suisse pour les Cyberthèses (Swiss Foundation for Cyberthoses) in 1999, in collaboration with the Laboratoire de Systèmes Robotiques (Laboratory of Robotic Systems) of the Ecole Polytechnique Fédérale de Lausanne (EPFL). It aims at developing systems of motor re-education and walking assistance, associating powered orthosis with trans-cutaneous and closed-loop electrical muscle stimulation: the MotionMaker™ and the WalkTrainer™. Its goal is to create active muscular participation that respects body dynamics of movements and to quicken re-education, whenever possible. In cases of total paralysis, its purpose is to activate lower limbs in order to reduce side-effects and complications resulting from immobilization. The FSC also makes it its ambition to conceive powered orthoses for autonomous walking with functional electric stimulation in its research programme: the WalkMaker™. To begin with, this doctoral thesis defines the biomechanical bases relative to lower limbs and pelvis. Anthropometrical, kinematic and dynamic data of body segments, as well as space-time parameters of walking have been specified. These data have been used in the theoretical models of the conception of the Powered Orthoses, and applied to the numerical simulations carried out in this study. Then we have presented the state of research on orthoses. The number of projects and the diversity of technologies offer a good illustration of the challenge posed when conceiving Powered Orthoses. So far there are no autonomous Powered Orthoses for re-education of ground walking subsequent to neurological trauma. If it is possible to find treadmills on the market, they are however deficient for medical purposes because of the subject's passivity and lack of pelvis mobility. We have then conceived two Powered Orthoses for a stationary training device: firstly, a serial orthosis of the exoskeleton type has been conceived with three articulations: hip, knee and ankle. Its activators consist in connectingrod and crank systems. Secondly, we have devised a device of leg manipulation with a parallel structure (in the shape of the Greek letter lambda λ). We have modelled these two powered orthoses and carried out a numerical simulation of two movements in order to compare their performances: leg press and cycling. The λ parallel powered orthosis gives better results. Before these findings, we built the prototype of the serial powered orthosis for clinical tests for feasibility of closed-loop controlled electric stimulation. The thesis then offers the design of an unprecedented powered orthosis to be integrated into a walker. We have analyzed and modelled a parallel structure with orthogonal connections and another one with λ connections. The comparative results of the numerical simulations of normal speed walking show that the orthogonal powered orthosis is optimal for an autonomous walker. We have built a prototype, and walking tests with healthy subjects prove the feasibility of such a concept. Finally we carried out two studies for a leg-powered orthosis, compatible with a pelvic PO and the walker. An exoskeleton is compared with a parallel structure. For these two systems, the numerical simulations and models give all the kinematic and dynamic features of the activators. Following these results, we chose the parallel PO so as to design an experimental prototype. It is currently being built as we are writing these lines. To complete the procedures, a chapter deals with the integration of the POs into a walker, with the motorization of the mobile frame and with a system of active body relieving. We also present a system of optical measurements of pelvic movements for diagnosis or for biomechanical studies. The last chapter offer guidelines for development in powered orthosis.

EPFL2007

Chargement

Afficher plus

Orthèses fonctionnelles à cinématique parallèle et sérielle pour la rééducation des membres inférieurs

Carl Schmitt

EPFL2007

Système robotique pour la mobilisation des membres inférieurs d'une personne paraplégique

Patrick Métrailler

EPFL2005

EPFL2016