New Approach to Friction Estimation with 4WD Vehicle

This research is a part of publicly funded project – FlexCar, which aims to build an autonomous vehicle. The vehicle offers open source software and construction models and should serve as a platform for rapid development and testing of new technologies. The project strives to bring new solutions for future mobility and overcomes some of existing limitations. The FlexCar platform has symmetrical design - it consists of two drive modules and one energy module between them. Both axles are steered, which allows a small turning radius. Furthermore, each wheel is equipped with one electromotor and can be accelerated separately. This can be used as an advantage for slip based friction estimation. Currently, ADAS functions have restrictions due to bad weather or road condition. With a continuous and driver-independent friction information, it would be possible to improve these functions and make a step towards autonomous driving. This paper shows first results from measurements done on the Handling Roadway test rig. Both, longitudinal and lateral slip are observed during accelerating/braking and steering.