In the many decades since researchers began to explore methods of creating them, active orthoses have progressed from complex research devices to nearly commercialized products. And while there are still many challenges associated with their development that have yet to be perfected, the advances in the field have been enormous. In this paper we review the history and discuss the state of the art of lower-limb active orthoses. We provide a design overview of hardware, actuation, sensory, and

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... trol systems for most of the devices that have been described in the literature, and end with a discussion of the major advances that have been made and hurdles yet to be overcome.