Worst-case evaluation methods for vehicles and vehicle control systems.

Worst-case evaluation methods are developed for the evaluation of dynamic systems in this dissertation. The objective of these methods is to systematically identify worst-case disturbances so that the performance of dynamic systems under extreme conditions can be evaluated. The generation of the worst-case disturbances is an optimization problem in a differential game framework. Depending on the number of players and the information structure, the worst-case evaluation problems can be classified into four types: one-player without preview information (1P), one-player with preview information (1PP), two-player without preview information (2P), and two-player with preview information (2PP). Classical optimal control and zero-sum two-player game theory are used to construct the worst-case disturbances. In general, the solution to a two-point boundary-value problem (TPBVP) is required for worst-case problems. When the system is linear, analytical solutions for the TPBVP can be obtained. For nonlinear systems, the worst-case problems need to be solved by numerically. Both analytical solutions and numerical methods are presented. The analytical solution of 2PP problems was derived, and is a key contribution of this dissertation. Two case studies on vehicle dynamic/control systems are presented to illustrate the procedures of the worst-case disturbance generation. The first case study is on the rollover and jackknifing of articulated trucks, which is formulated as a 1P problem. The second case study involves a vehicle dynamics control (VDC) system, whose worst-case disturbances are obtained by formulating a 2PP problem. In both case studies, the worst-case methods find the weakness of the target systems and result in instabilities. The identified worst-case disturbances do not exhibit features that can be easily constructed and explained by engineering intuition, which clearly shows the merits of the proposed methods.Ph.D.Applied SciencesAutomotive engineeringMechanical engineeringSocial SciencesTransportationUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/131268/2/9840594.pd