Audi A8 fully active electromechanical suspension powered by 48V electrical system; predictive adjustment using front camera
The new Audi A8 will feature a fully active, electromechanical suspension system which drives each wheel individually and adapts to the prevailing road conditions. Each wheel has an electric motor which is powered by the A8’s 48-volt electrical system—used for the first time as the main electrical system. (The Audi SQ7 TDI introduced in 2016 offered a 48V subsystem as well as a 12V system for the alternator. Earlier post. The new A8 also features a 48V mild hybrid capability (mHEV).)
Additional components include gears, a rotary tube together with internal titanium torsion bar and a lever which exerts up to 1,100 Nm (811.3 lb-ft) on the suspension via a coupling rod. The new Audi A8 makes its world debut at the Audi Summit in Barcelona on 11 July.
|Top: Overview of the active suspension system. Bottom: The rear-axle electromechanical system. Click to enlarge.|
Using its front camera, the A8 detects bumps in the road early on and predictively adjusts the active suspension. Even before the car reaches a bump in the road, the preview function developed by Audi transmits the right amount of travel to the actuators and actively controls the suspension.
In this way the suspension reacts precisely at the right time, virtually completely eliminating any vibrations and jolts. This complex process takes just a few milliseconds, with the camera generating information about the road surface condition 18 times a second. The electronic chassis platform (ECP) processes the road surface information and precisely controls all suspension components almost in real time.
In conjunction with the air suspension fine-tuned for the A8, the innovative suspension concept delivers an entirely new driving experience. Irrespective of the high level of comfort, the new luxury sedan sits close to the road even with a dynamic driving style.
The active suspension specifically influences and minimizes rolling movements when cornering, and pitching movements when braking or accelerating, for instance. The customer can drive dynamically while keeping the vehicle under control or work undisturbed in the rear.
The innovative combination of dynamic and rear axle steering resolves the conflict of aims between agility and stability in the shape of dynamic all-wheel steering: The steering characteristics are sporty and direct while ensuring a high level of handling stability; the steering feel encompasses a wide spread from comfortable through to intense feedback. The turning circle of the A8 is smaller than that of an A4.
In conjunction with the Audi pre sense 360˚ safety system, the active suspension on the new Audi A8 takes passive safety to a new level. The system uses the sensors networked in the central driver assistance controller (zFAS) to detect risks of a collision around the car.
In the event of an imminent side impact at more than 25 km/h (15.5 mph) the suspension actuators raise the body on the exposed side by up to 80 millimeters (3.1 in) within half a second. As a result, the collision is directed to the even stronger areas of the luxury sedan, such as side sills and floor structure. Hence the load on the occupants is reduced by up to 50% compared with a side impact where the body is not raised.