electrified powertrain, braking is performed to recover as much energy as possible for the drive unit. At the same time, there should be minimum impact on the subjectively perceived feel of braking. In series vehicles, this is a comfortrelated issue, but in motorsport, which usually involves operating at the dynamic limits, it is a matter of drivability at the limit, which is crucial for racing drivers to achieve constantly good lap times. “Even if the battery is fully charged and tem F O C U S 2 5 Photos: Doris Sporer, Peter Riedler powertrain, is still physically on the testbed. Wouldn’t it be so much easier to simply create a mathematical model of the drive system (or vehicle) and feed the simulated data into the driving simulator to get the driver’s feedback? “Well, no, it wouldn’t,” explains Gerhard Schagerl, Manager of Racing Vehicle Powertrain at AVL RACING, “and there are two good reasons why this wouldn’t work. First of all, it’s a very time-consuming and complicated job to create an accurate model of the powertrain along with all of its control units. Secondly, having a real vehicle on the testbed is much closer to reality than using a model.” AVL COMPLETE-VEHICLE INTEGRATION TEST BED SUITED FOR FORMULA-1 RACING For a testbed to be able to reproduce the dynamics of a race car, it has to be capable of representing the high dynamics of a racing vehicle in terms of acceleration, rapid load changes, high torques and speeds. The complete-vehicle integration testbed at the AVL Powertrain Technology Center (PTC) was specifically designed to meet Formula 1 requirements. But according to Matthias Dank, it is capable of much more. “Any elements not physically present in the setup can be simulated – just as required by the specific testing task. This includes the entire aerodynamics and the contact between the road surface and the tires. Of course, specific characteristics and peculiarities of any individual racing circuit can be reproduced in high fidelity as well. If the vehicle isn’t being operated by the driver in the simulator, there is of course also a ‘virtual racing driver’ who drives independently, as well as the classic test automation system,” Matthias Dank explains. OPTIMIZING THE BRAKE-BY-WIRE SYSTEM Another new and patented feature of the AVL test system is that in electrified racing vehicles the enthe tire braking system, consisting of the conventional hydraulic brake and the regenerative function, can be simulated and even tested as a real component. The reason for the growing significance of the vehicle brake is the electrification of the powertrain, which, to an increasing degree, is finding its way into the racing categories. In the case of porarily unable to draw any more current, the braking sensation for the driver must be exactly the same as during a recovery process. To be able to fine-tune the control strategy (brake-by-wire) between the drive unit and the hydraulic brake, high repeatability is a major advantage – and that is exactly what our test bed delivers,” points out Gerhard Schagerl. > The cockpit’s operating elements installed on the moving simulator platform are connected to the real race car on the integration test bed.
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