Here’s another biped robot, in the shape of a standing owl. I used only RIS 2.0 parts, plus a rotation sensor. This is a weight-shifting biped walker. It uses 2 motors, a touch sensor & a rotation sensor: a motor to shift the head (the RCX), a motor to rotate the feet, the touch sensor detects when the head is upright, the rotation sensor measures the legs position. This biped can change direction on its own footprints and can turn left or right.