Walking rehabilitation using exoskeletons is of high importance to maximize independence and improve the general well-being of spinal cord injured subjects. We present the design and control of a lightweight and modular robotic exoskeleton to assist walking in spinal cord injured subjects who can control hip flexion, but lack control of knee and ankle muscles. The developed prototype consists of two robotic orthoses, which are powered by a motor-harmonic drive actuation system that controls knee flexion–extension. This actuation module is assembled on standard passive orthoses. Regarding the control, the stance-to-swing transition is detected using two inertial measurement units mounted on the tibial supports, and then the corresponding motor performs a predefined flexion–extension cycle that is personalized to the specific patient’s motor function. The system is portable by means of a backpack that contains an embedded computer board, the motor drivers, and the battery. A preliminary biomechanical evaluation of the gait-assistive device used by a female patient with incomplete spinal cord injury at T11 is presented. Results show an increase of gait speed (+24.11%), stride length (+7.41%), and cadence (+15.56%) when wearing the robotic orthoses compared with the case with passive orthoses. Conversely, a decrease of lateral displacement of the center of mass (−19.31%) and step width (−13.37% right step, −8.81% left step) are also observed, indicating gain of balance. The biomechanical assessment also reports an overall increase of gait symmetry when wearing the developed assistive device.
Elastic actuators feature increased energy efficiency and improved human-robot interaction compared to directly driven concepts for active orthoses and prostheses. Structure and parameters of the elastic actuation system are often designed via a model-based minimization of energy consumption based on gait data gained from healthy individuals. However, natural motion exhibits variability among individuals and may not consider requirements of persons using assistive devices. A parametric study is performed examining the impact of varying gait characteristics on the energy consumption and constraints of an optimized (clutchable) series elastic actuator of the knee joint. Furthermore, friction parameters are varied to analyze the impact on actuator constraints. Results of the parametric study indicate increased energy consumption for a slower cadence compared to the healthy gait data for both systems. The clutchable series elastic actuator is less impacted by constraints than the series elastic actuator. The utilized models are evaluated experimentally at a test bench, indicating good accordance to the measured energy consumption. The results highlight the interrelation of friction and gait parameters with energy consumption and actuator constraints and indicate that the optimization procedure for the actuator design requires detailed models of component efficiency as well as subject-specific gait characteristics.
<p>Este artículo describe un manipulador móvil, bimanual y con capacidad de manipulación diestra denominado MADAR (de <em>Mobile Anthropomorphic Dual-Arm Robot</em>). Básicamente puede dividirse en dos partes, una base móvil y una estructura superior portando dos brazos en configuración antropomorfa con manos mecánicas diestras equipadas con sensores táctiles. La base, completamente de desarrollo propio, es de forma circular y tiene tres ruedas con un diseño novedoso que permiten una movilidad omnidireccional. La estructura superior integra elementos comerciales, como los brazos, las manos y distintos sensores, que han sido adaptados para su funcionamiento conjunto. El artículo incluye tanto la descripción de los principales elementos del hardware como del software desarrollado para su control y uso.</p>
Objective To describe the spinopelvic parameters in patients with conservatively treated thoracolumbar burst fractures. Methods Twenty-six patients with thoracolumbar burst fractures treated conservatively between 2008 and 2017 participated in the study. Inclusion criteria were acute burst-type fractures, located between T11 and L2, which compromised a single vertebral segment, did not present a neurological deficit, and had a minimum of 6 months of follow-up, excluding injuries that presented distraction or rotation, pathological fractures, and surgically treated cases. The sagittal and spinopelvic alignment parameters, including vertical sagittal axis, sacral slope, pelvic tilt, pelvic incidence, lumbar lordosis, and regional kyphosis, were analyzed. Results The values obtained for the sample showed that there was an increase in regional kyphosis and that the mean sagittal parameters and lumbar lordosis were within the values considered normal in the literature. Conclusion Patients with thoracolumbar burst fractures treated conservatively had no alterations in the spinopelvic parameters. Level of Evidence II; Retrospective study.
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