Challenge X: Crossover to Sustainable Mobility

Standing on the sizzling 150 degree tarmac at General Motor's desert proving grounds in Mesa, Arizona, with the ambient temperature around 115, one wonders if any of the hundred or so team members of the universities chosen were regretting that their engineering program made the final cut for this competition.

Mingling and talking with the young women and men, there wasn't a dour face displayed or sour word uttered. Primarily, it was a sea of smiling, happy faces.

That includes teams from universities that receive absolutely no credits for the hundreds of hours already spent on their project with more to come.

Yes, that's correct, zero credits. None. Nada.

So, that brings up the question: Why are they voluntarily frying in the desert sun at the end of an academic year, when many of their friends are off having fun doing whatever college students and grads do when classes are over?

The students were in the Arizona desert for year two of a three-year automotive engineering competition called Challenge X: Crossover to Sustainable Mobility. The competition and its forerunners, FutureCar, 1996 - '99 and FutureTruck, 2000 - '04, is a collaboration of government, industry and academia to explore clean, efficient automotive technologies.

General Motors and the U.S. Department of Energy were the headline sponsors for the Challenge X competition, as they were last year, and will be again in 2007.

Training Future Engineers
Challenge X challenges the 17 top North American universities to re-engineer a 2005 Chevrolet Equinox, a crossover sport-utility vehicle, to minimize energy consumption, emissions, and greenhouse gases while maintaining or exceeding the vehicle's utility and performance.

On the surface, that sounds like an attainable assignment when you consider that GM: supplied the vehicle for modification, threw in $10,000 seed money for each team, donated production parts such as engines and transmissions, provided engineering consulting for each team, competition facilities, operational support and $20,000 in prize money.

Additionally, other sponsors like The Mathworks, National Instruments and Freescale Semiconductor, provided hardware, software and training to integrate technologies into the competition vehicles and prize money awards.

Aaah, but there's a kicker. (Isn't there always one or two?) In this case, the Equinox—in addition to being greener with increased fuel economy—must maintain the performance, utility, creature comforts and safety attributes consumers want at the end of the competition next summer. And, the vehicle's total package has to be feasibly produced at a price that buyers wouldn't walk away from.

Unlike previous competitions, Challenge X university teams were not handed keys to vehicles the first year. Instead, the engineering students were introduced to GM's Global Vehicle Developmental Process. The point of Challenge X is to mimic GM's typical three-year vehicle design process.

The first year of the developmental process focused on the use of math-based modeling tools for vehicle design and subsystem control. Through the use of these tools, teams researched and compared technologies, and by the end of the year, had chosen their own unique powertrain architecture.

"It was tough to get students excited and focused about the first year's modeling, designing and planning," said Bryan Jungers, co-leader of the team from the University of California Davis. "Many prefer the hands-on part of the competition."

Mix of Hybrid Technologies
All teams selected hybrid electric vehicle (HEV) designs, some of which go beyond those considered by auto manufacturers. The most popular hybrid architecture that emerged from the competition, chosen by 12 of 17 teams, is called "through the road" parallel hybrid.

With this simplified hybrid arrangement, the front wheels are driven by a gasoline or diesel engine that is mounted as a traditional front wheel-drive system in the 2005 Chevrolet Equinox. Power for the rear wheels is provided by a differential that consists of an inline electric motor/gearbox directly driven by a large battery pack.

The only physical connection between the front-wheel tires and the rear-wheel tires is "through the road." Synchronizing and economizing both sections of the system is accomplished with "drive-by-wire" computer control systems.

Three teams chose a split parallel architecture. This employs two electric motors to drive the rear wheels in conjunction with a front-wheel-drive engine operation. Two teams chose a series hybrid architecture where the engine is used only to generate electricity for the motor(s) and batteries.

The University of California Davis, as they have in past competitions, chose a "charge-from-the-wall" plug-in HEV configuration. This design extends the electric-only operation range of the team's Equinox to 40 additional miles.

While the term hybrid vehicle is usually interpreted to mean a combination of an internal combustion engine and electric motors, the University of Michigan atAnn Arbor, combined a 1.9-liter direct injection turbodiesel with a hydraulic system to store the vehicle's mechanical energy, then assist the engine's operation.

Engine selections for Challenge X were dominated by highly efficient diesels and turbocharged spark-ignited engines operating on bio-based fuels, such as E85 (85 percent ethanol and 15 percent gasoline) and B20 (a diesel blend containing 20 percent biodiesel). These represent near-term approaches to improved efficiency. More advanced engines, such as highly dilute and boosted spark ignition engines and hydrogen-assisted ultra-lean burn combustion strategies represent more long term approaches.

Veering from the norm, the University of Waterloo—the only Canadian university participant and winner of the first year's competition—employed a hydrogen fuel cell as its primary propulsion system.

While hydrogen fuel cells are touted as the future for automotive transportation, their use is not limited to propulsion systems. Four teams employed fuel cell auxiliary power units to operate air conditioning and other accessories as well as aid HEV propulsion.

Most teams drew on a nickel-metal hydride battery for their power supply pack (the same type used in today's hybrids). The University of Akron also added ultracapacitors, and West Virginia University's power supply came from ultracapacitors alone. Pennsylvania State University and the University of California Davis employed lithium-ion battery packs.

Challenging Events
The first day of the competition is crucial, a rigorous safety and technical inspection—each vehicle has to be mechanically safe to qualify for any competition event. This is a "pass or become spectators" evaluation.

From there on, the judging gets tougher. Engineers, technicians and automotive experts from GM, the Argonne National Laboratory, U.S. Department of Energy and Natural Resources Canada evaluate and grade each team in scored events. The events measure all aspects of the vehicle including acceleration, trailer towing and fuel economy. A total vehicle developmental review evaluates how closely teams followed the second year of GM's vehicle development process.

While team members are seated behind the steering wheel for events like trailer towing, judges drive the vehicles in events like braking and handling. Teams consider it noteworthy to be able to drive their vehicles off the testing pad after the judges have driven a vehicle to near extinction after 20 minutes.

Significantly reducing tailpipe emissions is one of the main goals of Challenge X, and the emissions tests account for nearly 20 percent of the competition scores. While everyday emissions testing may look at hydrocarbons and nitrous oxide, Challenge X looks for improvement in greenhouse gas emissions, such as carbon dioxide and non-methane organic gases.

The Envelopes Please!
Overcoming problems throughout the week, including one resulting from desert heat, Virginia Tech's solution of a split parallel architecture with a GM Saab 2.0-liter turbocharged spark-ignited engine fueled by E85, took first place honors. In addition to winning lowest emissions and lowest petroleum consumption, the Virginia Tech team also won in the category of best braking and handling and best-written technical report.

Steve Boyd, a mechanical engineering graduate student and leader of Tech's 40-person team, said the team decided to fuel the vehicle with E85, a product of corn ethanol, because its use means "energy security" for the country.

"Ethanol is produced here in the U.S. and we control it; it's not like oil where we have no control over its production," Boyd said.

When I drove the Virginia Tech Equinox, the "start/stop" function of the hybrid system worked erratically, something Boyd said the team could solve in the upcoming year in time for the next year's final round. The University of Wisconsin at Madison team placed second with its through-the-road parallel electric hybrid with a diesel 1.9-liter turbocharged engine running on biodiesel.

Third place was awarded to Mississippi State University who converted their Equinox to a split parallel, through-the-road hybrid configuration that runs on B20 biodiesel.

"The demonstration of performance and realization of vehicle designs in this year of Challenge X was phenomenal," said Argonne's Steve Gurski, lead technical coordinator for Challenge X." Testing in record temperatures in the Phoenix area challenged the student teams to their limits, and they were able to rise to the occasion. If the fantastic results of year two are any indication, year three of Challenge X will be truly spectacular."

One thing is certain for next year: cooler temperatures. The nine-day competition judging takes place at GM's Milford proving grounds outside Detroit, Michigan.

Challenge X Participating Universities:
Michigan Technological University
Mississippi State University
Ohio State University
Pennsylvania State University
Rose-Hulman Institute of Technology
San Diego State University
Texas Tech University
University of Akron
University of California, Davis
University of Michigan
University of Tennessee
University of Texas at Austin
University of Tulsa
University of Waterloo
University of Wisconsin-Madison
Virginia Tech
West Virginia University

Larry E. Hall is editor of Northwest Auto News Service and a freelance automotive journalist based in Olympia, Wash. He has an intense interest in future automotive technology.

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