Audi’s Dakar electric-drive challenge
The Audi RS Q e-tron competition vehicle is scheduled to race in Dakar Rally in January 2022, with Audi Motorsport fielding its range-extended EV prototype.
The 500kW prototype features a 250kW motor-generator unit (MGU) in each axle, derived from the version used in the Audi e-tron FE07 Formula E racing car, but the Dakar prototype also has a third MGU. This third unit recharges the 400kg, 50kWh battery by means of a two-litre, in-line, four-cylinder TFSI engine that acts only as a generator.
The range-extending engine is set to operate between 4500 and 6000rpm and to consume as little petrol as possible, because the daily distances of the Dakar stages are up to 800 kilometres in length.
There’s no bulky transmission and the axles aren’t connected by propshafts. Instead, Audi has created a virtual centre differential, with software deciding upon torque distribution between the axles.
In its Formula E powertrain Audi has already achieved a system efficiency of over 97 percent, so there’s not much room for improvement. However, the situation is quite different with the battery and energy management, where Audi expects to garner experience from racing that can help with production vehicles.
A look inside the Audi RS Q e-tron reveals an aeroplane cockpit in which screens and displays are spread across the entire width of the instrument panel.
Originally, there was a clear division of tasks in cross-country rallying: the driver drove, the co-driver navigated. These roles have changed, because the regulations limit navigational tasks to very precise options and rules, and the former paper road book for the track is now digital. So, the Audi RS Q e-tron redistributes various functions between drivers and co-drivers.
Steering, accelerating and braking are the main tasks for the driver, who fully concentrates on the terrain. The driver doesn’t have to change gears, because the electric drive with energy converter in the Audi RS Q e-tron no longer requires a manual transmission.
Centrally visible in the cockpit is the double-cranked aluminum handbrake lever. It is coupled with the innovative brake-by-wire system that combines the hydraulic brake with a recuperation system. So, pulling on the handbrake helps to recover energy, as does operating the footbrake. But the essential purpose of the handbrake in rally-racing is to induce a slide of the RS Q e-tron before corners. The brief slowing of the rear wheels forces the car into part-rotation that makes direction changes particularly agile.
There are eight control buttons on the steering wheel directly in front of the driver. Among other things, they control data entries in the software, if the driver wants to store an anomaly with a time stamp in the memory.
They also control the speed-limiter that can be activated in zones where a maximum speed is prescribed.
Behind the steering wheel, a display sits in the driver’s lower field of vision and provides information on tyre pressures, travel direction and the current speed. It also contains important warnings so that the driver can react in the event of an imminent system shutdown or disconnection of the high-voltage battery, for example.
Two small displays mounted above and toward the windshield bring essential information into the field of vision and a repeater on the left shows the compass direction.
A central display between the driver and co-driver contains information on tyre pressures, the selected brake balance, the brake-by-wire system and other functions. The information is highlighted in green when a function or system is working properly, or in red when an error occurs.
A switch panel is located underneath and various functions are stored on 24 freely assignable areas, including air conditioning actuation. Less frequently used functions can be called up on rear pages. In the event of damage, individual systems can be switched off at this panel.
All this has to be done as faultlessly as possible, in rough terrain, at speeds of up to 170 km/h, for hours on end. The co-pilot assumes a high level of responsibility in addition to his original main task, which is to navigate.
“I now spend only half my energy on navigation and the other half on operating the car, but I love this new challenge,” said Edouard Boulanger, Stéphane Peterhansel’s co-driver.
The route of the upcoming stage is no longer issued the evening before, as in the past. The teams receive this route information only 15 minutes before the start of each stage. Emil Bergkvist, who shares the cockpit with Mattias Ekström, sees this as an advantage:
“As a driver, I come from classic sprint rallying, so for me, this is the ideal time to switch to cross-country rallying as a co-driver, because now even the established co-drivers have to get used to these new rules.”
The short-notice information on the route as well as the switch to a digital road book format pose major challenges. To orient themselves in the terrain and at the same time keep to the prescribed route, the three co-drivers Emil Bergkvist, Edouard Boulanger and Lucas Cruz look at two tablet screens that replace the previous paper road books. They are operated by two remote controls connected by cables.
On the screen on the left, the road book shows the way through the terrain. Only if this tablet should fail are the crews allowed to open and use the sealed paper road book supplied, or face a penalty. The tablet on the right contains the GPS navigation and validates the digital waypoints that each participant must drive to.
When the car reaches the radius of a waypoint, the driver also sees the arrows in the right-hand repeater below the windshield, indicating the direction to the waypoint.
The biggest difference from a navigation system in a production car is that the race system provides only compass directions, distances, pictograms, special aspects and hazard warnings in the road book. Therefore, the GPS system in the rally car is deliberately of only limited help to the teams.
At the same time, the system serves as a control instrumen that can check whether the participants have kept to the route and the speed in speed-control zones.
The cockpit is completed by the Iritrack system in the centre console that is used in emergencies. In the event of trouble, the co-driver can inform the organiser directly whether medical assistance is required.
Extreme precision, speed and a flood of tasks characterise the digitised work in the ultra-modern cockpit of the Audi RS Q e-tron.