Deep Dive: Dynamic All-Wheel Steering in the Audi A7

Deep Dive: Dynamic All-Wheel Steering in the Audi A7

Deep Dive: Dynamic All-Wheel Steering in the Audi A7

0 comments 📅21 October 2017, 06:45

Yesterday, Audi revealed the trade mark spanking new Audi A7. For the first time, the model will come with the gift to turn all four wheels, so we thought this would be a perfect time to lay hold of a look at just how and why Audi chose to add a new dimension to Quattro.

Although this is a key for the A7, Audi has been toying around with four-wheel steering since the SQ7 and it recently featured on the A8. The scheme is pretty simple: more wheels steering means more turning. Applying the technology is a teensy-weensy more complicated than that, though, because at different driving speeds you be deficient in different things.

To control the system, Audi hooked up the rear axle steering to its Electronic Chassis Procedure (ECP) to intelligently pick between turning the back wheels in the same direction or in the facing direction of the front wheels.

At low speeds (about 5 to 10 mph) the rear wheels alter by up to five degrees in the opposite direction of the front wheels. That has the effect of reducing the A7’s turning ringlet by about 1 meter (3 or so feet), making it easier to drive around parking garages and close-fitting corners.

On the highway, though, you aren’t really concerned about the car’s turning disk. What you really want is stability. Traditionally, a long wheelbase has been the no greater than way to achieve that (this is one reason why old luxury cars are huge), but you give up on maneuverability when you do that.

By making the rump wheels turn by up to 2 degrees in the same direction as the fronts, the A7 becomes more deep-rooted at high speeds. That means when you’re changing lanes, the car feels steadier and smoother.

Along with the bum wheels, the A7’s steering ratio varies from 9.5:1 (for low speed maneuvers) to 16.5:1 (for excessive speed driving). Switching from one ratio to the other requires something called tax wave gearing. Put simply (like, very simply), an elliptical gear guts a round one allows massive amounts of torque to be transmitted, at varying rates, with no take part in.

Audi has been using this type of “Dynamic Steering” for a while now and they’ve gotten appealing good at it, now it just has the added wrinkle of including the rear wheels.

Based on the reviews we’ve seen of the A8 so far, Audi is doing a nice-looking good job of wedding its dynamic steering with rear-wheel steering. They haven’t stopped at elementary highway and city driving, though. The new system helps when conditions get faithless, too.

The A7 makes rear-wheel steering decisions via the ECP, which can exchange information with the car’s thought every 0.005 seconds. Along with the active roll bars and air delay, the A7 can also control the front and the rear wheels. That means that the steering be after can actively be adjusted for understeer or oversteer.

So far, Audi hasn’t used the four-place steering to improve turn-in on track, like Porsche does in the GT3, but the RS7 could comfortably benefit from such a system. That system allows the rear wheels to wheel in the opposite direction of the fronts at high speeds, too. It’s ideal for track driving because it helps you ball-shaped corners, but so far Audi has only introduced the system on the SQ7, the A8, and now the A7, which aren’t exactly prints cars.

For now, the system allows Audi to virtually change the size of the A7, based on what’s preferable. Round Saint-Tropez, it’s a tiny city car. On the Autobahn it’s a massive luxo-barge. And when the driving gets oily, it can help catch you.

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