ABS Lab
More brake pressure does not always stop a vehicle sooner. Once a wheel locks, the tire leaves its peak-friction region. Compare No ABS, Threshold ABS, and PID Slip under identical vehicle and road conditions.
Slip ratio λ = (v − Rω) / v measures the difference between vehicle and tire circumferential speed. Deploy an ice patch mid-stop to watch the controller release and rebuild pressure after a sudden friction change.
Peak friction arrives before lockup
Beyond the μ-slip peak, increasing slip reduces braking force instead of adding more.
ABS does not hold constant pressure
It watches wheel speed and cycles through apply, hold, and release to regulate slip.
The optimum moves with the road
Dry, wet, and icy surfaces have different peak μ and optimal λ, so one fixed setting is not always best.
Continue with speed, position, and altitude PID experiments in Control Lab.