Overall Project Summary This proposal finalizes the design of a portable ankle robot as a therapeutic device to reverse foot drop and restore safe independent walking after stroke, then conducts a rigorous randomized clinical trial to establish clinical efficacy for this new market application. Product development is inspired by our five positive clinical studies that demonstrate that ankle robot-mediated functional motor learning is most effectively conducted in the context of locomotor task-oriented training. In Phase I, we pursued finalization of a lighter weight, battery powered, and wirelessly controlled ankle robot (AMBLE) that meets basic clinical usability standards for regular mobility-focused physical therapy (PT). Specific Phase I accomplishments include designing and bench testing a functional beta prototype that meets key safety, stability, and comfort metrics during over-ground walking and mobility tasks for full integration into PT. Phase II (3-yrs) is a blinded, randomized clinical trial investigating the hypothesis that 9 weeks (18 sessions) of PTR is more effective than PT alone to reverse foot drop as assessed by instrumented gait biomechanics and blinded clinician assessment. Our results will establish safety and initial efficacy for reversal of foot drop as a new market application filling an unmet need, and shift care toward PT-integrated robotic exoskeletons across other impaired joints.