Optimal control techniques for assessing feasibility and defining subsystem level requirements: an automotive case study

The use of models is widespread in automotive industry in the preliminary feasibility assessment of novel powertrains, determination of system configuration and subsystem requirements, and operating strategy. Although optimal control problems arise naturally within this context when faced with analysis of transient performance requirements, they are rarely treated other than by simulations. The objective of this paper is to illustrate how optimal control problems of this kind arise and can be solved numerically using optimal control techniques. We also demonstrate an array of meaningful conclusions that can be generated from such an optimal control study. The case study treated in the paper deals with a turbocharger power assist system (TPAS). The extent to which this system can reduce the diesel engine turbo-lag is determined via the numerical solution of a minimum-time optimal control problem.