A nonlinear post impact path controller based on optimised brake sequences

This paper investigates brake-based path control of a passenger vehicle, aimed at reducing secondary collision risk following an initial impact in a traffic accident. Previous results from numerical optimisation showed that, at varying severity levels of post-impact states, there exist three identifiable components within the optimal control strategy so as to reduce the lateral deviation. The paper presents a path controller, based on nonlinear optimal control theory, that incorporates the three components. It is shown that friction adaptation may be implemented in a very efficient manner; the controller deals with different levels of road friction by scaling the dynamic variables from a fixed reference level. The approach provides an algorithm for adapting switching thresholds between the different components of the controller. In this study it is verified that the controller can deal with a wide range of kinematic conditions, and compares favorably with previous results of open-loop trajectory optimisation