Robot legs propelled entirely by their own weight that can walk with a human-like gait without motors or external control have been developed by researchers at the Nagoya Institute of Technology in Japan, ExtremeTech reports.

The robot legs are basically just an imitation of human physiology, with thighs and lower legs made out of aluminum that are the same length as their human counterparts, and ankles and knee joints for articulation. They can walk down a slope powered by gravity alone.