Behind the wheel in the virtual world.
It may seem like child’s play, but driving simulators is in fact an important role in vehicle development as engineers test the driving performance of new Audi models before they hit the roads.
10 October, 2019
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 (164kW), 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 hurt, 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.
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 sweat already,” he says laughing.
He’s right. It is really 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 it really well. It’s basically made up of a driver’s cabin, mounted on a hexapod, (hex – Greek: six, pod – Greek: foot) and a four metre tall, 180 degree screen that stands in front.
I’m in a bare room, sitting in the dynamic driving simulator on the grounds of Audi Technical Development
The driving simulator is part of the comprehensive virtual development chain being used at Audi
The hexapod’s six electrically driven cylinders allow the driving simulator to move freely and precisely within the room – up to 60 centimetres in all directions. The steering resistance is simulated with a steering actuator that is mounted under the steering wheel. Seven LED projectors fire an image onto the screen – a highway, a racetrack, a suburban street. You name it.
“The driving cabin moves on the hexapod according to the steering input and the image automatically adjusts in response to this movement. This creates the impression that you are actually driving in a car,” explains Uhlmann.
“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 co-operation with a doctoral candidate.” The room is painted black and the lights are turned off while the simulator is operating, creating 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.
“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 behaviour 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 metres at a speed of about 60km/h. To make the braking manoeuvre feel just like it does in reality, you would also need to move the driver’s cabin back 36 meters during braking,” says Uhlmann.
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.
We still have to make use of real vehicles — usually expensive prototypes — in order to assess driving dynamics and comfort
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