Many research groups are developing robotic exoskeletons which aim to assist motor rehabilitation for individuals after neurological injuries. As a rehabilitation tool, the primary goals of robotic exoskeletons are to reduce manual assistance from therapists and to achieve optimal training outcomes. Although the first objective has been realized by many current robotic devices, producing better rehabilitation outcomes with robotic devices is still a developing area of research. To design better robotic devices, it is important to understand the principles governing how humans learn to interact with the robotic assistance and to identify the gait parameters humans prioritize as objectives for their gait pattern. I used two types of robotic exoskeletons to examine rapid locomotor adaptation to mechanical assistance. The specific questions I addressed were: (1) how do neurologically intact subjects adapt their walking patterns to a powered orthosis that provides dorsiflexion assistance? (2) Do subjects walk with joint kinetic patterns during robotic-assisted walking similar to joint kinetic patterns during unassisted walking? (3) Is locomotor adaptation rate dependent on exoskeleton strength? (4) Is an increased stretch reflex inhibition a potential mechanism for reducing soleus recruitment when walking with the exoskeleton? (5) Do stretch reflex responses during unexpected gait perturbations appropriately meet the mechanical requirements of gait? In the first experiment, the exoskeleton was configured to provide dorsiflexion assistance proportional to the voluntary activation of the tibialis anterior muscle (i.e., ankle dorsiflexor). For the rest of experiments, the exoskeleton was configured with two artificial pneumatic muscles providing plantar flexion assistance proportional to the soleus muscle activation (i.e., ankle plantar flexor). The double muscle exoskeleton provided twice the mechanical capability of the previous single-muscle exoskeleton design (Cain et al. 2007; Gordon and Ferris 2007; Kinnaird and Ferris 2009). The results provide important insights into the principles governing human locomotor adaptation. The information can be used to aid in designing powered devices and may be helpful in optimizing gait rehabilitation therapies. In addition, the findings should be helpful in the development of biologically realistic neuromusculoskeletal computer simulations of human walking.

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This paper presents the design and the clinical vali-dation of an upper-limb force-feedback exoskeleton, the L-EXOS, for robotic-assisted rehabilitation in virtual reality (VR). The L-EXOS is a five degrees of freedom exoskeleton with a wearable structure and anthropomorphic workspace that can cover the full range of motion of human arm. A specific VR application focused on the reaching task was developed and evaluated on a group of eight post-stroke patients, to assess the efficacy of the system for the rehabilitation of upper limb. The evaluation showed a significant reduction of the performance error in the reaching task (paired t -test, p < 0.02). (далее…)

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A method for controlling movement using an active powered device including an actuator, joint position sensor, muscle stress sensor, and control system. The device provides primarily muscle support although it is capable of additionally providing joint support (hence the name “active muscle assistance device”). The device is designed for operation in several modes to provide either assistance or resistance to a muscle for the purpose of enhancing mobility, preventing injury, or building muscle strength. The device is designed to operate autonomously or coupled with other like device(s) to provide simultaneous assistance or resistance to multiple muscles.

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A combined 450,000 Americans suffer from multiple sclerosis, chronic carpal tunnel syndrome, and muscular dystrophy; debilitative disorders that result in a loss of muscle strength and dexterity within the afflicted individual. A controlled orthoticexoskeleton presents a solution by amplifying a user’s residual strength to restore precision pinch and/or power grasp motions. In order to optimize system response time and control accuracy, a two-bit binary state control algorithm was designed using LabVIEW v8.5. The states of the control system were refined using positional and object-sensing information supplied via negative feedback from Hall effect angular sensors and force sensing resistors. Forearm EMG was recorded and used to characterize hand strength with and without the mechanical assistance generated from the hand-assistive exoskeleton. The control system was tested using simulated sensor feedback data and has proven to be a robust design. The controller will be integrated with a glove-like, hand-based exoskeleton. The complete system was designed to restore hand functionality through the amplification of precision pinch and/or power grasp.

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Over 450,000 Americans suffer from debilitative disorders resulting in the loss of proper hand function. A lightweight, non-cumbrous, orthotic hand exoskeleton was designed to restore normal pinching and grasping finger motions. Three functional digit mechanisms were designed: a thumb, index, and grouped third digit, comprised of the middle, ring, and small fingers. Each phalange was enclosed by a series of cylindrical aluminum bands connected at the centers of rotation of each joint. Bowden cables were mounted beneath each digit to provide active flexion, mimicking the tendons in the hand. A spring extension mechanism maintained constant tension in the Bowden cables, and during relaxation, returned the actuated digits to a fully extended resting position. Individually controlled actuators mounted on a forearm assembly produced 15 N of tensile force in each cable. The orthotic hand exoskeleton will be integrated with a digital control system currently under development in this laboratory. The complete system was designed to restore hand functionality through the amplification of precision pinch and/or power grasp.

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