Quadruped Ground-Reaction Force QP (2D)

Whole-body controllers for legged robots don't just plan joint motions — every cycle they also solve a small quadratic program that splits a desired net body force and moment across whichever feet are currently on the ground, subject to each foot only being able to push (never pull) and only within its Coulomb friction cone. This 2D simulator draws a quadruped from above, lets you drag or dial in a desired push, lean torque, friction coefficient, and body weight, and lifts individual legs on demand, then solves that contact-force QP live via a minimum-norm equality projection alternated with an exact closed-form projection onto each foot's friction cone. Unlike a 3D scene, the friction-cone projection is shown in its own native 2D plane (normal force vs. tangential force magnitude) for every foot at once, making the geometry of "safely inside the cone" versus "saturated against it" directly visible.