Abstract
In this paper we aim at achieving optimal control design for vehicle propulsion systems by attaining a maximum performance index function, while satisfying the driveline power requirements and physical constraints of the system. The performance index is typically described by a cost function, which consists of single or multiple objective criteria. The cost function normally depends on the vehicle propulsion configuration. This paper reviews and classifies the objective metrics that can be used to measure vehicle performance. The state-of-art of performance indices utilized in the optimizations and optimal control strategies for both conventional and hybrid electric vehicles are surveyed and discussed to form the basements for proposing the candidates for new performance indices for vehicular propulsion systems. A case study for a novel PowerShift-Automated Manual Transmission (PS-AMT) powertrain system will be introduced in which a cost function including fuel consumption, power reserve and shifting cost are proposed for the optimal control problem. The correlations and potentially strong dependencies among those objective criteria in that cost function are addressed by cost function-based analyses using the Singular Value Decomposition (SVD) method. It is found that this method can be used in order to construct an appropriate cost function for the optimal control problem design for this specific powertrain configuration. The method of analyzing the cost function used in this paper can be extended to other types of vehicular propulsion systems.
Keywords: Performance Indices, Singular Value Decomposition, Conventional Vehicles, Hybrid Electric Vehicles