The research unit Technical Dynamics and Vehicle Dynamics has developed a drift-assist that interacts with the human driver and supports the driver when drifting¹⁾. It allows also the non-expert driver to master critical manoeuvres and road conditions successfully, and to support the driver when learning to understand the dynamic behaviour of the vehicle in a really exciting way.

After a detailed theoretical analysis of the nonlinear system behaviour and comprehensive simulation studies, a control strategy for the coordination of the human driver and the electric motors of the powertrain of a 4WD electric vehicle has been developed. While the powertrain is above all responsible for the traction capabilities of a vehicle, it is used here rather unconventionally, in particular as a yaw moment actuator for stabilisation.

Two control approaches for the drift-assist, one classical control approach and one based on reinforcement learning (ML) methods, öffnet in einem neuen Fenster, have been elaborated. Last year, both were implemented in a Porsche Taycan and tested on the proving ground in Nardo (Italy), Wachauring (ÖAMTC Testgelände), and Papenburg (Germany). In the last week of February 2024, the drift-assist had to stand the harsh test conditions on the ice-lakes in the very North of Sweden. Part of the ice lake is used as a winter proving ground, where polished ice or packed snow is a challenge for all kinds of vehicle controllers.

The test campaigns included members from Cariad and Porsche and the research unit Technical Dynamics and Vehicle Dynamics. Both control approaches for the drift-assist have been proven successful and will next be compared in more detail. So far, the classical controller is very effective; the ML-based controller seems to be very robust against different drivers and frictional conditions between tyre and road.

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¹⁾ The drift, better called powerslide, is a manoeuvre at the limits of vehicle handling. For the human driver, it is a challenge to control and stabilise this unstable cornering condition when tyre forces at the rear axle are typically saturated. The wheel spin of the rear wheels is used to control the lateral force of the rear tyres, and in this way, the yaw motion of the vehicle is controlled. Using actuators to stabilise the drift autonomously is a popular research topic, but it becomes even more complex if a human driver is involved.