While most mobility options for persons with paraple-gia or paraparesis employ wheeled solutions, significant adverse health, psychological, and social consequ-ences result from wheelchair confinement.Modern robotic exoskeleton devices for gait assistance and rehabilitation, however, can support legged locomotion systems for those with lower extremity weakness or paralysis. The Florida Institute for Human and Machine Cognition (IHMC) has developed the Mina, a proto-type sensorimotor robotic orthosis for mobility assistance that provides mobility capability for paraplegic and paraparetic users. This paper describes the initial concept, design goals, and methods of this wearable overground robotic mobility device, which uses compliant actuation to power the hip and knee joints. Paralyzed users can balance and walk using the device over level terrain with the assistance of forearm crutches employing a quadrupedal gait. We have initiated sensory substitution feedback mechanisms to augment user sensory perception of his or her lower extremities. Using this sensory feedback, we hypo-thesize that users will ambulate with a more natural, upright gait and will be able to directly control the gait parameters and respond to perturbations. This may allow bipedal (with minimal support) gait in fu-ture prototypes.

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Категория: Научные статьи | 1 Комментарий »

Brain–machine interfaces use neuronal activity recorded from the brain to establish direct communication with external actuators, such as prosthetic arms. It is hoped that brain–machine interfaces can be used to restore the normal sensorimotor functions of the limbs, but so far they have lacked tactile sensation. Here we report the operation of a brain–machine–brain interface (BMBI) that both controls the exploratory reaching movements of an actuator and allows signalling of artificial tactile feedback through intracortical microstimulation (ICMS) of the primary somatosensory cortex. Monkeys performed an active exploration task in which an actuator (a computer cursor or a virtual-reality arm) was moved using a BMBI that derived motor commands from neuronal ensemble activity recorded in the primary motor cortex. ICMS feedback occurred whenever the actuator touched virtual objects. Temporal patterns of ICMS encoded the artificial tactile properties of each object. Neuronal recordings and ICMS epochs were temporally multiplexed to avoid interference. Two monkeys operated this BMBI to search for and distinguish one of three visually identical objects, using the virtual-reality arm to identify the unique artificial texture associated with each. These results suggest that clinical motor neuroprostheses might benefit from the addition of ICMS feedback to generate artificial somatic perceptions associated with mechanical, robotic or even virtual prostheses.

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When Licklider published Man-Computer Symbiosis in 1960, he stated that ldquoIt seems entirely possible that, in due course, electronic or chemical ldquomachinesrdquo will outdo the human brain in most of the functions we now consider exclusively within its province. (p.2)rdquo The brain-machine interface Licklider envisioned has been extended beyond his initial conceptions by noninvasive and portable technologies, such as EEG and near-infrared based optical brain imaging devices. These noninvasive neuroimaging tools facilitate better interfacing with the brain by providing the underlying principles that govern the brain’s ability to adapt to and utilize new interface paradigms. Moreover, these enabling technologies can guide the development of prosthetics to compensate for cognitive deficits within impaired populations, as well as enhance cognitive performance for healthy populations. Functional near-infrared spectroscopy (fNIR), an emerging optical brain imaging system, will be introduced along with an illustration of its potential role in the development of cognitive prostheses. fNIR is a wearable neuroimaging device that enables the continuous, non-invasive, and portable monitoring of NIR light absorbance of oxygenated and deoxygenated hemoglobin in blood. Hemodynamics measured by fNIR is similar to functional MRI and provides information about ongoing brain activity. Drexel’s Optical Brain Imaging Lab, comprised of an interdisciplinary team of engineers, cognitive and motor neuroscientists, and neurorehabilitation scientists have developed and integrated fNIR imaging techniques into an array of research paradigms to assess cognitive and motor activities of individuals with and without impairments. Applications of fNIR include cognitive workload and human performance assessments, credibility assessments, learning during performance of a gripping task with an electromyographically controlled exoskeleton gripper with haptic feedback, assessment of recovery from — anesthesia, and brain-machine interface for communication and control. This talk will briefly address current developments of cognitive prostheses as well as the future direction of the field.

Категория: Ищем научные статьи | Нет комментариев »

To harness the increased dexterity and sensing capabilities in advanced prosthetic device designs, amputees will require interfaces supported by novel forms of sensory feedback and novel control paradigms. We are using a motorized elbow brace to feed back grasp forces to the user in the form of extension torques about the elbow. This force display complements myoelectric control of grip closure in which EMG signals are drawn from the biceps muscle. We expect that the action/reaction coupling experienced by the biceps muscle will produce an intuitive paradigm for object manipulation, and we hope to uncover neural correlates to support this hypothesis. In this paper we present results from an experiment in which 7 able-bodied persons attempted to distinguish three objects by stiffness while grasping them under myoelectric control and feeling reaction forces displayed to their elbow. In four conditions (with and without force display, and using biceps myoelectric signals ipsilateral and contralateral to the force display,) ability to correctly identify objects was significantly increased with sensory feedback.

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Rehabilitation robotics specializes in designing machines, such as exoskeletons, which can be utilized to restore function in patients recovering from physical trauma. The proposed Assistive Rehabilitation Arm Orthosis (A.R.A.O.) is designed to restore function and rehabilitate patients suffering from muscular diseases as well as mild-stroke. Clinical studies have shown that task-based repetitive training can improve motor abilities and enhance functional performance in those recovering from stroke. The proposed design improves on the popular four bar linkage systems used in many modern orthoses by incorporating a dynamic feedback system that actuates elastic elements, allowing users to lift heavier objects, while still remaining portable. The dynamic feedback system incorporates force-sensing resistors in conjunction with a linear actuator to vary the tension in the tension bands. The device not only allows patients to perform day-to-day lifting tasks but also has the potential for use in rehabilitation.

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