In Level 3+ autonomous driving and mechanical steer-by-wire where mechanical steering columns are eliminated, a single electronic failure cannot result in system shutdown. Fail-operational architectures employ dual independent power feeds, mirrored ARM lockstep processors, dual-wound brushless DC steering motors, and voting logic to maintain full vehicle lateral control during any single hardware or software failure.
In conventional automotive EPS, a single stator winding failure leaves the vehicle unguided. Modern steer-by-wire replaces this with a dual-wound motor: two completely isolated three-phase stator windings share a single magnetic rotor. Each winding is driven by a separate inverter bridge and microcontroller. If channel A detects a short-to-ground, channel B instantaneously ramps torque from 50% to 100% in 1.2 milliseconds, preventing the driver from experiencing any steering resistance loss.