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The continued demands of improving fuel economy while maintaining or improving vehicle performance and emissions is the driving force behind new powertrain control features. This paper describes a Model-in-the-Loop (MIL) environment, which is used in the development of advanced powertrain control systems. The MIL is a cost effective and convenient tool for testing the control implications of new features such as, variable valve timing (VVT), variable valve lift (VVL), gasoline direct injection (GDI), etc. It is also helpful in testing the effects of different calibrations and powertrain configurations prior to implementing them on a vehicle or test bench. The overall structure of the MIL includes a control module, vehicle plant models, and signal display blocks. Each of these will be described with the focus being on the plant models and the overall MIL environment.

Embedded systems continue to become more complex. As a result, more companies are utilizing model-based design (MBD) development methods and tools. The use of MBD methods and tools is helpful in increasing time to market and having instant feedback on the system design. One area that continues to mature is the testing and verification of the MBD systems. This paper introduces a hybrid approach to functional tests. The test system is composed of simulation software and real-time hardware. It is not always necessary to test a system in a real-time environment, but it is recommended if the goal is to deploy the system to a situation that requires real-time response. Vehicle drive cycles and powertrain control are utilized in this research as the example test case for this paper. In order to test the algorithms on a real-time system, it is necessary to understand the target controller's computing limitations and adjust the algorithms to meet these limitations.