Authors: Jian Jun Zhu; Amir Khajepour; Jonathan Spike; Shih-Ken Chen; Nikolai Moshchuk
Addresses: Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Avenue, West Waterloo, Ontario, N2L 3G1, Canada ' Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Avenue, West Waterloo, Ontario, N2L 3G1, Canada ' Application Engineering, Maplesoft Inc., 615 Kumpf Drive, Waterloo, Ontario N2V 1K8, Canada ' Global R&D Center, General Motors (GM) Corporation, 30001 Van Dyke Avenue, Warren, MI 480093, USA ' Global R&D Center, General Motors (GM) Corporation, 30001 Van Dyke Avenue, Warren, MI 480093, USA
Abstract: Knowledge of tyre-road friction force is important in many vehicle control systems such as torque vectoring, differential braking and stability control systems. However, tyre friction forces and the factors affecting the friction forces cannot be directly measured by commonly used vehicle sensors. Therefore, an accurate estimation of the friction forces and friction index is crucial for a successful vehicle control design. Although a large number of friction estimation algorithms have been developed, those algorithms mainly focus on a single direction, either longitudinal or lateral, but cannot estimate the tyre friction in a combined condition. This paper presents an integrated friction estimation algorithm based on a half-car vehicle model that can simultaneously estimate the combined friction condition along the longitudinal and lateral directions with some basic measurements. The algorithm consists of a number of estimations for vehicle roll angle, tyre friction forces, vehicle longitudinal and lateral velocities, and tyre-ground friction index. The proposed algorithm has been verified with actual vehicle test results. The test results demonstrate that the algorithm has a fairly good fidelity for estimation of tyre friction forces, vehicle velocities and road-friction conditions that is described quantitatively by a tyre-road friction index.
Keywords: integrated estimation; tyre friction forces; vehicle velocity; tyre-road friction; vehicle speed; half-car models; vehicle modelling; vehicle control; torque vectoring; differential braking; stability control; friction estimation; longitudinal direction; lateral direction; vehicle roll angle.
International Journal of Vehicle Autonomous Systems, 2016 Vol.13 No.2, pp.114 - 139
Received: 09 Jul 2014
Accepted: 07 Jan 2015
Published online: 02 Sep 2016 *