Nonlinear vehicle side-slip estimation with friction adaptation

A nonlinear observer for estimation of the longitudinal velocity, lateral velocity, and yaw rate of a vehicle, designed for the purpose of vehicle side-slip estimation, is modified and extended in order to work for different road surface conditions. The observer relies on a roadtire friction model and is therefore sensitive to changes in the adhesion characteristics of the road surface. The friction model is parametrized with a single friction parameter, and an update law is designed. The adaptive observer is proven to be uniformly globally asymptotically stable and uniformly locally exponentially stable under a persistency-of-excitation condition and a set of technical assumptions, using results related to Matrosov's theorem. The observer is tested on recorded data from two test vehicles and shows good results on a range of road surfaces. Key words: automotive vehicles, nonlinear observers, side-slip estimation, velocity estimation, friction

• Type: Journal
• Year: 2008
• Where: AUTOMATICA
• Authors: Håvard Fjær Grip, Lars Imsland, Tor Arne Johansen, Thor I. Fossen, Jens Kalkkuhl, Avshalom Suissa
• Keywords: AUTOMATICA 2008, Estimation, Friction Model, Nonlinear Observers