Design of unknown input fuzzy observer for vehicle dynamics estimation with road geometry consideration

Abstract

A methodology for estimating vehicle dynamics whith road geometry consideration is presented in this paper. Vehicle sideslip and roll parameters are estimated in the presence of the road bank angle and the road curvature as unknown inputs. The unknown inputs are then estimated using the observer results. This information about the road geometry and vehicle parameters is needed in the driver assistance systems to be able to calculate the risk index of a rollover or a lane departure crashes. Taking into account the unmeasured variables, an unknown inputs (TS) observer is then designed on the basis of the measure of the roll rate, the steering angle and the lateral offset given by the distance between the road centerline and the vehicle axe at a look-ahead distance. Synthesis conditions of the proposed fuzzy observer are formulated in terms of Linear Matrix Inequalities (LMI) using Lyapunov method. Simulation results show good efficiency of the proposed method to estimate both vehicle dynamics and road geometry.