Design synthesis of car-trailer systems with active trailer differential braking strategies.

Abstract

To this date, various control strategies based on linear vehicle models have been proposed and developed for improving the lateral stability of car trailer (CT) systems. Is a linear-model-based controller applicable to active safety systems for CT systems under emergency operating conditions, such as an evasive maneuver at high lateral accelerations? In order to address the problem, the following innovative investigations have been conducted: 1) a comparative study of typical linear and nonlinear CT models have been carried out to examine the dynamic responses of the models under the emulated test maneuvers; and 2) the applicability of an Active Trailer Differential Braking (ATDB) controller designed using a linear CT model is tested and evaluated under the conditions that the controller is applied to a CT system represented by the selected linear and nonlinear models. The current research leads to the following insightful findings: 1) the selected linear CT model is effective to predict the lateral stability of CT systems; 2) under the regular evasive maneuvers at low lateral accelerations (less than 0.5g), this linear model can be used to provide dynamic responses that are in good agreement with the selected nonlinear models; 3) the ATDB controller designed using the linear model can effectively improve the lateral stability of CT systems under regular evasive maneuvers at low lateral accelerations, but the controller is not applicable to CT active safety systems under emergency evasive maneuvers at high lateral accelerations. The insightful findings resulted from the thesis will provide valuable design guidelines for the development of active safety systems for CT systems.