BIPED ROBOT – 21022
A biped robot is a robot with two legs that are used for support and propulsion. Usually, but not always, such robots have arms and a head, so they are androids.
Physically, biped robots are unstable unless equipped with specialized balancing systems. Humans can manage with two legs because the brain and inner ear together constitute a feedback system that provides a good sense of balance. The human sense of balance can be duplicated electromechanically, but the designs are sophisticated and expensive.
Robots that use legs for propulsion generally have four or six legs, because these designs offer better inherent stability than the biped scheme.