At static ride height
Curves through wheel travel
What the model does
Upright. The knuckle is a rigid body held by the links. Each link is a fixed-length distance constraint between its chassis pivot and its upright joint; a MacPherson strut adds a line constraint that keeps the knuckle sliding along the strut axis. At every 2.5 mm of travel the six-degree-of-freedom pose is solved with Newton's method.
Outputs. Camber and toe come from the wheel spin axis. Caster, KPI, scrub radius and trail come from the steering axis through the ball joints (or the strut top). The front-view and side-view instant centres come from the upright's instantaneous rotation, and the roll centre from the contact patch's sideways velocity, so it stays correct when the arms are parallel. Motion ratio is damper length change per millimetre of wheel travel.
Body roll. Each side is solved at its own travel, the body is laid over level ground, and the roll centre is where the two force lines cross, so its sideways movement in roll is real.
Conventions. The left corner is modelled; the right is its mirror. Travel + is bump. Camber − is top inboard. Toe + is toe-in. Caster + is top rearward. Anti-dive assumes outboard brakes; anti-squat assumes a chassis-mounted differential.
Not modelled: tyre deflection, bushing compliance, steering input (Ackermann), springs and anti-roll bars, so the roll angle is set by you rather than predicted from cornering load.