A Novel PWA Lateral Dynamics Modeling Method and Switched T-S Observer Design for Vehicle Sideslip Angle Estimation

In this article, a novel vehicle sideslip angle estimation method is proposed using the Takagi–Sugeno (T–S) observer based on a piecewise affine (PWA) lateral dynamics model. Since conventional lateral dynamics models have complex structures and nonlinearities, difficulties in sideslip angle observer design and online implementation are inevitable. To address nonlinearities, the PWA and T–S fuzzy modeling approaches are applied in this article. First, a nominal PWA model is obtained using the nominal tyre load and tyre-road friction coefficient. An explicit relationship between the PWA model parameters and the tyre load, tyre-road friction coefficient is deduced based on the Dugoff tyre model. Then, a novel PWA lateral dynamics model is obtained considering a varying tyre load and tyre-road friction coefficient. Due to the residual nonlinear terms, this PWA model is further converted into a T–S fuzzy model. Finally, a switched T–S observer is designed as it is computationally simple and efficient enough for online estimation. To validate the effectiveness of the proposed approach, experiments are conducted on both low- and high-friction coefficient roads. Experimental results show that the proposed PWA modeling technique is effective and the T–S observer can estimate the sideslip angle well under both stable and unstable steering maneuvers.