Gait analysis for designing a new assistive knee brace

Assistive knee brace is a species of wearable lower extremity exoskeletons. In this research, an assistive knee brace was developed by integrating a multifunctional actuator with a custom-made knee-ankle-foot orthosis. In the study, the location of the actuator is moved up to the lateral side of the hip, instead of knee joint. Waist belt and shoulder belt are appended on the knee brace. This paper aimed to improve the design of the assistive knee braces through gait analysis. By walking with the knee braces, the spatial and temporal gait parameters, joint kinematics and joint kinetics parameters were evaluated, and the changes from normal walking were compared as well. The experimental results showed that walking with the developed knee brace provided minimal hindrance to the wearer. © 2011 IEEE

Comfort-Centered Design of a Lightweight and Backdrivable Knee Exoskeleton

This paper presents design principles for comfort-centered wearable robots and their application in a lightweight and backdrivable knee exoskeleton. The mitigation of discomfort is treated as mechanical design and control issues and three solutions are proposed in this paper: 1) a new wearable structure optimizes the strap attachment configuration and suit layout to ameliorate excessive shear forces of conventional wearable structure design; 2) rolling knee joint and double-hinge mechanisms reduce the misalignment in the sagittal and frontal plane, without increasing the mechanical complexity and inertia, respectively; 3) a low impedance mechanical transmission reduces the reflected inertia and damping of the actuator to human, thus the exoskeleton is highly-backdrivable. Kinematic simulations demonstrate that misalignment between the robot joint and knee joint can be reduced by 74% at maximum knee flexion. In experiments, the exoskeleton in the unpowered mode exhibits 1.03 Nm root mean square (RMS) low resistive torque. The torque control experiments demonstrate 0.31 Nm RMS torque tracking error in three human subjects.Comment: 8 pages, 16figures, Journa

Design of a Knee Exoskeleton for Gait Assistance

abstract: The world population is aging. Age-related disorders such as stroke and spinal cord injury are increasing rapidly, and such patients often suffer from mobility impairment. Wearable robotic exoskeletons are developed that serve as rehabilitation devices for these patients. In this thesis, a knee exoskeleton design with higher torque output compared to the first version, is designed and fabricated. A series elastic actuator is one of the many actuation mechanisms employed in exoskeletons. In this mechanism a torsion spring is used between the actuator and human joint. It serves as torque sensor and energy buffer, making it compact and safe. A version of knee exoskeleton was developed using the SEA mechanism. It uses worm gear and spur gear combination to amplify the assistive torque generated from the DC motor. It weighs 1.57 kg and provides a maximum assistive torque of 11.26 N·m. It can be used as a rehabilitation device for patients affected with knee joint impairment. A new version of exoskeleton design is proposed as an improvement over the first version. It consists of components such as brushless DC motor and planetary gear that are selected to meet the design requirements and biomechanical considerations. All the other components such as bevel gear and torsion spring are selected to be compatible with the exoskeleton. The frame of the exoskeleton is modeled in SolidWorks to be modular and easy to assemble. It is fabricated using sheet metal aluminum. It is designed to provide a maximum assistive torque of 23 N·m, two times over the present exoskeleton. A simple brace is 3D printed, making it easy to wear and use. It weighs 2.4 kg. The exoskeleton is equipped with encoders that are used to measure spring deflection and motor angle. They act as sensors for precise control of the exoskeleton. An impedance-based control is implemented using NI MyRIO, a FPGA based controller. The motor is controlled using a motor driver and powered using an external battery source. The bench tests and walking tests are presented. The new version of exoskeleton is compared with first version and state of the art devices.Dissertation/ThesisMasters Thesis Mechanical Engineering 201

Robotic Rehabilitation Devices of Human Extremities: Design Concepts and Functional Particularities

International audienceAll over the world, several dozen million people suffer from the effects of post-polio, multiple sclerosis, spinal cord injury, cerebral palsy, etc. and could benefit from the advances in robotic devices for rehabilitation. Thus, for modern society, an important and vital problem of designing systems for rehabilitation of human physical working ability appears. The temporary or permanent loss of human motor functions can be compensated by means of various rehabilitation devices. They can be simple mechanical systems for orthoses, which duplicate the functions of human extremities supplying with rigidity and bearing capacity or more complex mechatronic rehabilitation devices with higher level of control. We attempt to cover all of the major developments in these areas, focusing particularly on the development of the different concepts and their functional characteristics. The robotic devices with several structures are classified, taking into account the actuation systems, the neuromuscular stimulations, and the structural schemes. It is showed that the problems concerning the design of rehabilitation devices are complex and involve many questions in the sphere of biomedicine, mechanics, robot technology, electromechanics and optimal control. This paper provides a design overview of hardware, actuation, sensory, and control systems for most of the devices that have been described in the literature, and it ends with a discussion of the major advances that have been made and should be yet overcome

Feasibility Study of a Wearable Exoskeleton for Children: Is the Gait Altered by Adding Masses on Lower Limbs?

We are designing a pediatric exoskeletal ankle robot (pediatric Anklebot) to promote gait habilitation in children with Cerebral Palsy (CP). Few studies have evaluated how much or whether the unilateral loading of a wearable exoskeleton may have the unwanted effect of altering significantly the gait. The purpose of this study was to evaluate whether adding masses up to 2.5 kg, the estimated overall added mass of the mentioned device, at the knee level alters the gait kinematics. Ten healthy children and eight children with CP, with light or mild gait impairment, walked wearing a knee brace with several masses. Gait parameters and lower-limb joint kinematics were analyzed with an optoelectronic system under six conditions: without brace (natural gait) and with masses placed at the knee level (0.5, 1.0, 1.5, 2.0, 2.5 kg). T-tests and repeated measures ANOVA tests were conducted in order to find noteworthy differences among the trial conditions and between loaded and unloaded legs. No statistically significant differences in gait parameters for both healthy children and children with CP were observed in the five “with added mass” conditions. We found significant differences among “natural gait” and “with added masses” conditions in knee flexion and hip extension angles for healthy children and in knee flexion angle for children with CP. This result can be interpreted as an effect of the mechanical constraint induced by the knee brace rather than the effect associated with load increase. The study demonstrates that the mechanical constraint induced by the brace has a measurable effect on the gait of healthy children and children with CP and that the added mass up to 2.5 kg does not alter the lower limb kinematics. This suggests that wearable devices weighing 25 N or less will not noticeably modify the gait patterns of the population examined here.Cerebral Palsy International Research FoundationStavros S. Niarchos Foundatio

Kinematic and dynamic modeling and validation of an assistive robotic device for knee rehabilitation

La articulación de la rodilla está frecuentemente expuesta a lesiones en personas de todas las edades. En todos los casos, la terapia física se prescribe para recuperar la fuerza y la movilidad de un paciente. Los dispositivos de asistencia robótica están ganando la atención de la comunidad y apuntan a mejorar la calidad de vida de los pacientes. En este artículo, se propone el diseño mecánico de un dispositivo de rehabilitación de rodilla de enlace de 5 barras basado en la definición de los parámetros físicos de la población colombiana y/o latinoamericana, de acuerdo a los datos de antropometría. Se obtiene el modelo dinámico completo del sistema de rehabilitación propuesto y se realizan las comparaciones respectivas de movimiento con el prototipo real para desarrollar y evaluar estrategias de control apropiadas en trabajos futuros. Para este propósito, se presenta la formulación cinemática del dispositivo y luego se deriva la dinámica utilizando dos enfoques para validar el modelo; se obtiene la ecuación de movimiento utilizando la aproximación de Lagrange y un método algebraico que simplifica el modelado. Ambas aproximaciones producen un modelo único, que se valida en simulación y en ensayos experimentales, mostrando la funcionalidad del sistema y la validez de los modelos cuando se realizan rutinas de rehabilitación.The knee joint is frequently exposed to injuries in people of all ages. In all cases, physical therapy is prescribed to recover the strength and mobility of a patient. The robotic assistance devices are gaining the community attention and aim to improve the quality of life of patients. In this article, we propose the mechanical design of a 5-bar-linkage knee rehabilitation device based on the definition of the physical parameters of Colombian and/or Latin-American population, according to anthropomorphic data. We obtain the complete dynamic model of the proposed rehabilitation system and perform the respective comparisons of movement with the real prototype in order to develop and evaluate appropriate control strategies in future work. For this purpose, we present the kinematic formulation of the device and then we derive the dynamics using two approaches to validate the model; we obtain the motion equation using the Lagrange approach and an algebraic method that simplifies modeling. Both approaches yield a unique model, which is validated either in simulation and by experimental trials, showing the functionality of the system and the validity of the models when performing rehabilitation routines.Pregrad

A review of the effectiveness of lower limb orthoses used in cerebral palsy

To produce this review, a systematic literature search was conducted for relevant articles published in the period between the date of the previous ISPO consensus conference report on cerebral palsy (1994) and April 2008. The search terms were 'cerebral and pals* (palsy, palsies), 'hemiplegia', 'diplegia', 'orthos*' (orthoses, orthosis) orthot* (orthotic, orthotics), brace or AFO

The Use of Functional Electrical Stimulation (FES) to Produce Functional Movement in Individuals with Paraplegia

Spinal cord injury (SCI) affects approximately 7600 to 11000 people per year, and alters every aspect of the individuals\u27 lives. SCI primarily affects young Caucasian adults. The majority are between 16 to 30 years old, with the average age being 19. Motor vehicle accidents account for 35% to 40% of SCI cases reported, with violence in close second at 25%. Currently, the highest neurological category is of complete paraplegia followed by incomplete quadriplegia. SCIs often cause many complications due to decreased physical activity and changes in bodily functions. Among treatment options, functional electrical stimulation (FES) is used to restore a variety of physical and physiological functions. Some of the most promising and controversial research lies in the areas of bowel and bladder elimination, gait and exercise training, and also walking. It functions by stimulating the peripheral nerve, sending electrical impulses through electrodes placed on the skin in order to generate a muscular contraction. The goal of FES is to generate purposeful, goal-oriented movement, aimed at completing a task. Based on past research, FES has shown to benefit paralyzed individuals by reducing secondary complications, improving physiological responses, producing bone and muscle changes, and increasing cardiovascular fitness. The purpose of this literature review is to determine whether or not FES produces beneficial functional movement in paraplegics. The procedure used to perform this study will be a literature review based on a collection of journal entries, articles, statistics, and experimentations of scientists, various health professionals, and other researchers