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Challenge X is now a four-year competition among seventeen North American universities with the goal of re-engineering a 2005 Chevrolet Equinox for improved fuel economy and reduced emissions, while maintaining performance, utility, safety, and consumer acceptability. Primarily sponsored by the U.S. Department of Energy and General Motors, the program also attracted sponsorship from many other industry and government organizations. Teams achieve the goals of the competition by utilizing advanced hybrid power trains, novel control strategies, alternative fuels, lightweight materials, and innovative emissions control techniques.
Challenge X emphasizes the evolution of these technologies by following a progression that is representative of GM's Global Vehicle Development Process. Consequently, the first year of the competition (2004-05) stressed the validation of the chosen hybrid systems in a modeling and laboratory environment. The second year demonstrated engineered systems ready for implementation into the Equinox vehicle, as well as delivery of a road-worthy "mule," with primary focus on the power train. In year three, just concluded, teams demonstrated vehicles that meet the GM 99% Buy-Off criteria. This includes presenting a vehicle that would be considered 99% ready for production.
Challenge X vehicle development process: Year 1
During the first year of Challenge X, the university teams were required to develop, model, simulate, and analyze various hybrid-vehicle architectures and the actuators to construct them. From this analysis, the final architecture emerged. At this point, an extensive amount of modeling and simulation occurred to evaluate the feasibility of hypothetically meeting the Vehicle Technical Specifications as set by the competition.
The details of the architecture chosen by the Ohio State team will be shown later; however, this process involved the creation of a quasi-static and dynamic simulation tools (also to be discussed in detail later) for evaluating fuel economy, emissions, and drivability. These tools were created using The MathWorks software and the iterative process visualized in the figure below. By following this process and comparing simulation results to the limited amount of actual data supplied by the competition, the Ohio State team was able to create a Model-Based Design that yielded confident results.
The Year 1 hybrid-vehicle development process resulted in a power train control architecture.
Year 2
After the first year, each team received a stock 2005 Chevrolet Equinox from General Motors. The goal of this second year was to integrate the architecture developed in Year 1 onto the actual vehicle; moreover, each team was scored on the accuracy with which they predicted the Vehicle Technical Specifications (VTS) in year one, to the measured VTS with the completed prototype vehicle.
Throughout the year, the Ohio State team utilized the strategy as shown in the figure below. Using the various parameters determined in simulation in conjunction with Real-Time Workshop®, control strategy parameters were flashed to a target and fine-tuned on the vehicle to meet the requirements set by the team.
As lessons were learned from vehicle testing, the simulation tools developed in year one were also refined further increasing their accuracy. This was such that the Ohio State team won First Place honors for "Best Realization of VTS Targets" in the second year of the competition.
Year 3
Year 3 of the competition focused on refinement of the vehicle to meet the 99% Buy-Off standards as set by General Motors. Due to the nature of the required improvements, the Ohio State team created a number of other simulation tools with MathWorks products to implement features such as start-stop and traction control.
As can be seen in the graphic below, the team utilized their simulation tools to predict vehicle behavior and tuned control strategy parameters prior to the implementation on the vehicle. Once suitable results are obtained from these tools, the tuned parameters are uploaded to the vehicle using Real-Time Workshop. The process ends with vehicle testing and repeats with the evaluation of vehicle performance.
Year 4
The recently added fourth, and final, year of the competition begins in Fall 2007 and focus on further vehicle refinement, as well as public outreach regarding sustainable mobility and other goals of Challenge X.
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