An Object-Oriented Modelling Method for Evolving the Hybrid Vehicle Design Space in a Systems Engineering Environment

摘要

A combination of environmental awareness, consumer demands and pressure from legislatorshas led automotive manufacturers to seek for more environmentally friendlyalternatives while still meeting the quality, performance and price demands of theircustomers. This has led to many complex powertrain designs being developed inorder to produce vehicles with reduced carbon emissions. In particular, within thelast decade most of the major automotive manufactures have either developed or announcedplans to develop one or more hybrid vehicle models. This means that to becompetitive and o er the best HEV solutions to customers, manufacturers have toassess a multitude of complex design choices in the most e cient way possible. Eventhough the automotive industry is adept at dealing with the many complexities ofmodern vehicle development; the magnitude of design choices, the cross coupling ofmultiple domains, the evolving technologies and the relative lack of experience withrespect to conventional vehicle development compounds the complexities within theHEV design space.In order to meet the needs of e cient and exible HEV powertrain modelling withinthis design space, a parallel is drawn with the development of complex softwaresystems. This parallel is both from a programmatic viewpoint where object-orientedtechniques can be used for physical model development with new equation orientedmodelling environments, and from a systems methodology perspective where thedevelopment approach encourages incremental development in order to minimizerisk. This Thesis proposes a modelling method that makes use of these new tools toapply OOM principles to the design and development of HEV powertrain models.Furthermore, it is argued that together with an appropriate systems engineeringapproach within which the model development activities will occur, the proposedmethod can provide a more exible and manageable manner of exploring the HEVdesign space.The exibility of the modelling method is shown by means of two separate case studies,where a hierarchical library of extendable and replaceable models is developed inorder to model the di erent powertrains. Ultimately the proposed method leads toan intuitive manner of developing a complex system model through abstraction andincremental development of the abstracted subsystems. Having said this, the correctmanagement of such an e ort within the automotive industry is key for ensuringthe reusability of models through enforced procedures for structuring, maintaining,controlling, documenting and protecting the model development. Further, in orderto integrate the new methodology into the existing systems and practices it is imperativeto develop an e cient means of sharing information between all stakeholdersinvolved. In this respect it is proposed that together with an overall systems modellingactivity for tracking stakeholder involvement and providing a central point forsharing data, CAE methods can be employed in order to automate the integrationof data.