 Specific examples include The emPOWER from BionX, the Proprio Foot from Ossur, and the Elan Foot from Endolite.Various research groups have also experimented with robotic legs over the last decade.Central issues being researched include designing the behavior of the device during stance and swing phases, recognizing the current ambulation task, and various mechanical design problems such as robustness, weight, battery-life/efficiency, and noise-level.