Robotic technologies have greatly advanced in recent years, making robotic exoskeletons feasible as real devices instead of being limited to science fiction. However, prototype devices do not perform as well as expected, specifically in regard to reducing the metabolic cost of locomotion. To improve exoskeleton designs, we need to understand principles of neural adaptation to powered assistance so that future designs allow humans and machines to act as a coordinated system. The University of Michigan Human Neuromechanics Laboratory has designed robotic exoskeletons for assisting human locomotion with the primary intent of identifying principles of neuromechanical control and adaptation to powered assistance. Our most recent research is on developing mobile brain imaging techniques with the eventual goal of building a brain-controlled robotic lower limb exoskeleton.