Dynamic Driving Simulators: Why They Will Make Decisions About The Audis Of The Future

source: Alexander Stiehle  for Audi AG

Developing, testing, and experiencing the feeling of driving — in the driving simulator, engineers test the driving performance of new Audi models before they hit the roads. Audi author Alexander Stiehle was “on the road” in one. He had heaps of fun and, while he was at it, learned how the simulator saves time and money during development.

One minute and 54 seconds — the results of my first round in the Audi driving simulator. That could be faster, I think to myself. I push the accelerator to the floor and the engine revs. With 220 HP, I shoot across the starting line of the Zandvoort racing track in the Netherlands. Just before the sharp Tarzan Corner, I brake hard and steer to the right. The high steering torque is starting to make my arms start, but I don’t give up. Instead, I grit my teeth…

Suddenly, the lights turn on. The racing track in front of me fades until I can hardly see it, and I slowly return to reality. I’m not in Zandvoort. The car I’m sitting in isn’t real.

Audi driving simulator: the race track goes digital

No, I’m in a bare room, sitting in the dynamic driving simulator on the grounds of Audi Technical Development. And, out of the blue, Richard Uhlmann, project manager and development engineer from the “Chassis Concept Properties” department, is standing next to the door of my car.  “It’s exhausting, isn’t it? You’re dripping in sweat already,” he says, laughing. I get out and wipe the beads of sweat from my temples with the back of my hand.

He’s right. It really is exhausting — even though it isn’t real. The Audi driving simulator is in a class of its own. It tries to replicate reality, and it does that very well. It’s basically made up of a driver’s cabin, which is mounted on a hexapod (hexa – Greek: six, pod – Greek: foot), and a four-meter-tall, 180-degree screen that stands in front of the cabin.
The hexapod’s six electrically driven cylinders allow the driving simulator to move freely and precisely within the room — up to 60 centimeters in all directions. The steering resistance is simulated with a steering actuator that is mounted under the steering wheel. Seven LED projectors project an image onto the screen — a highway and a race track, among others.

Advanced automotive testing: the long development process was worth it

“The driving cabin moves on the hexapod according to the steering input. The image automatically adjusts in response to this movement. This creates the impression that you are actually driving in a car,” explains Uhlmann, as we both look at the driving simulator. “The driving performance needs to be replicated as precisely as possible so that the drivers don’t feel motion sickness. To that end, we developed our own algorithm in cooperation with a doctoral candidate.” The room is painted black and the lights are turned off while the simulator is operating. This creates the best possible contrast for the projection on the screen.

Development of the driving simulator began in 2012 and it has only recently been put to use. The Audi engineers want to assess the driving characteristics of the Audi models right from the beginning of the development process. To do this, they can feed all the relevant vehicle data such as weight, suspension, or wheelbase into the simulator. “The driving simulator is part of the comprehensive virtual development chain that we are already using successfully to design new chassis.

There are still physical limitations: the perfect driving simulation is close to the original

“Despite that, we often have to make use of real vehicles — usually expensive prototypes — in order to assess driving dynamics and comfort. That’s where the driving simulator comes in to play. In the future, we want to use it to experience driving characteristics very early on, in order to make pivotal decisions about the project. That saves time and resources and makes it possible for us to influence the vehicle concept early on.” The simulator allows the engineers to, for example, determine how the roll behavior of the prototype feels subjectively. The vehicle concept can then be adjusted accordingly.

But as real as the 3D driving simulator might make a situation seem, it still has its limits.

Some movement patterns can be replicated only partially, or not at all. “A car has a braking distance of around 36 meters at a speed of about 60 km/h. To make the braking maneuver feel just like it does in reality, you would also need to move the driver’s cabin back 36 meters during braking,” says Uhlmann.

Record time in the driving simulator: challenge accepted

Despite that, you can still lose control of the car in the driving simulator. If you drive too fast going into a curve, the rear of the car will begin to skid, the image rotates, and the simulator gives you a good shake. That gives you a very realistic driving experience, despite the limited acceleration. As to the question of what the best time for Zandvoort in the simulator is, Uhlmann answers: “A colleague drove a lap in one minute and 28 seconds.” I get back in. Challenge accepted.