Add one capability at a time to the same machine skeleton — a cam that remembers a motion, actuators that put torque into joints, tilt and foot-sole senses, and the feedback that pulls a falling body back — and feel the difference between having a human shape and responding like one.
Torso, pelvis, legs, arms. However closely the outline resembles a person, this skeleton does not know its own state and generates no force. What makes a humanoid work is not the silhouette but a closed circulation of joints, actuation, sensing, and control. Add one capability at a time to the same body and test where that boundary lies.
Turn the machine skeleton and find the joints that pass force from the pelvis down to the soles.
This is a simplified model for reading the relationship between centre of mass and support region. It does not predict the toppling limit of a real machine.
