Control and Implementation of a Powered Lower Limb Orthosis to Aid Walking in Paraplegic Individuals

I'm sure with some modifications this could easily be adapted for a hemiplegic, So ask your doctor who is going to do that for you.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3402219/

Abstract

This paper describes a powered lower-limb orthosis that is intended to provide gait assistance to spinal cord injured (SCI) individuals by providing assistive torques at both hip and knee joints, along with a user interface and control structure that enables control of the powered orthosis via upper-body influence. The orthosis and control structure was experimentally implemented on a paraplegic subject (T10 complete) in order to provide a preliminary characterization of its capability to provide basic walking. Data and video is presented from these initial trials, which indicates that the orthosis and controller are able to effectively provide walking within parallel bars at an average speed of 0.8 km/hr.