Centre-of-mass projection
Base-of-support ellipse
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This simulation teaches the basics of karate stances (kihon) through the real biomechanics behind them: your centre of mass, projected onto the floor, is pushed around by a damped inverted-pendulum model whenever an incoming force lands from the front, back, or either side. Pick a stance — front (zenkutsu-dachi), horse (kiba-dachi), back (kokutsu-dachi), or cat (neko-ashi-dachi) — each with its own base-of-support footprint and corrective stiffness, choose whether to absorb the hit softly or brace against it firmly, and watch the margin of stability, peak sway and recovery time score exactly how well that stance and response held the line.