FIGURE H-9 Hardware-in-the-loop.

FIGURE H-9 Hardware-in-the-loop.

to drive the plant and converts these signals into the physical variables connected to the plant model. The plant model calculates the physical variables that represent the outputs of the plant, which are converted into electrical signals that represent the voltages produced by the sensors that feed the controller.

Another option to evaluate fuel consumption is component-in-the-loop (CIL), a combination of HIL and RCP. In CIL, an entire system is connected to a source emulating the rest of the vehicle. For example, Figure H-10 shows an engine and its controller connected to an AC dynamometer that would be controlled to represent the rest of the vehicle losses.

Figure H-11 shows a similar approach using a battery and a DC supply source emulating the remainder of the vehicle. In both cases the hardware component will be the one that (1) represents the new technology or (2) has not been properly validated yet or (3) cannot be accurately modeled (e.g., due to transients or thermal issues).

It should also be noted that more than one component can be hardware while some of them are still emulated. For example, both an engine and a battery could be hardware while the rest of the power train and the vehicle are emulated. One of the issues in using that approach, however, is the potential for communication-related delays since some of the signal transfer most likely has to go through the Internet.

An approach to characterize a system using several hardware components without building the entire vehicle is shown in Figures H-12 and H-13. The Modular Automotive Technology Testbed (MATT) has been developed to easily replace components by switching different plates. In the example below, a pretransmission parallel hybrid is shown. This concept allows the entire power train (or most of it) on a rolling chassis dynamometer in a controlled environment. However, like most approaches, it also shows some limitations, including lack of under-hood thermal management or the presence of a T-shaped reduction box to connect the wheels.

FIGURE: H-10 Engine on dynamometer. SOURCE: Courtesy of Cummins.

FIGURE: H-10 Engine on dynamometer. SOURCE: Courtesy of Cummins.



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