YAW-ROLL STABILITY ANALYSIS OF ROAD VEHICLES USING PWA BIFURCATION

The yaw stability analysis and rollover detecting are two of major objects for road vehicle safety control. This paper proposes a method of yaw-roll stability analysis of road vehicles by using the piecewise affine (PWA) bifurcation analysis method. For yaw stability analysis, the stable regions of vehicle yaw dynamics model are obtained by analysing the fixed points under varying steering angle based on the bifurcation analysis method. To estimate the variation of positions and types of all possible fixed points quantitatively, a qualified PWA approximation of lateral tire force model is established. Moreover, a modified load transfer ratio (LTR) is proposed based on lateral dynamics to detect the potential rollover. The fixed points estimation results of PWA bifurcation analysis method is evaluated by plotting the phase planes of original nonlinear yaw dynamic model under multiple varying parameters and the modified LTR is also verified by comparing with several traditional rollover indexes (RIs).