Breaking Convention - Part 2
By Bill Moore
As Chris Borroni-Bird explained in part one of our interview, it is two rapidly developing technologies that make the GM AUTOnomy concept vehicle possible. One is its GM-developed PEM fuel cell system which is housed in the chassis "Skateboard" under the passenger "pod."
The other technology is "drive-by-wire."
First used in modern jet aircraft like the Airbus A300 -- and called "fly-by-wire" for obvious reasons -- drive-by-wire uses electrical signals instead of mechanical linkages to control the vehicle. Instead of snaking lines of tubing and heavy steel shafts, the driver's inputs are translated into digital or analog electric signals which control small actuators and microprocessors. Think of it like the difference between an old mechanical typewriter and your modern computer keyboard.
On the old typewriter, your keystrokes where linked through a system of levers to a slim piece of mechanical type face. Now the same process is done through a tiny bundle of wires or even wirelessly. Even more significantly, you're no longer stuck with one or two type faces. You can now have a virtually limitless set of fonts and even more. The same keyboard controls robots, your home's appliances, communicates with others around the globe, plays thousands of different computer games, and regularly visits EV World.
"The beauty of the by-wire is that it offers us so much more flexibility to configure the interior."
While GM may initially offer a conventional set of controls like steering wheel, foot pedals and a standard instrument panel, the "X-wire" system now allows owners a choice of control options, as well as giving GM designs new interior layout options.
Borroni-Bird envisions a time when a sports car could have a different driver interface than a traditional luxury car. In his words, there could be much more customization in the driver interface. Drive-by-wire might eventually translate into a single joystick, much like the type you buy today for a computer flight simulator game. All the controls for the car could placed in that single joystick; directional control, acceleration, braking. And that joystick could be moved from right to left or even in the center of vehicle. The use of digital display screens would allow what was the passenger's navigation map to now become the speedometer, fuel gauge, etc.
Even the arrangement of the passenger cabin layout is suddenly open to all sorts of new possibilities. Without the need to accommodate an engine compartment, both the exterior design of the vehicle and interior configuration of seating are no longer confined to a heretofore limited range of choices.
Borroni-Bird did acknowledge that one thing that probably won't change is the "trunk" or boot, as it is called in England. He thinks that people are still going to want to have someplace to store their luggage and groceries and the safest place for that is behind the passenger cabin.
SOME SAFETY ISSUES
The AUTOnomy concept does raise a number of important safety issues. One of the more obvious is the lack of any "heavy metal" in front of the passenger cabin. Most people assume that having an engine compartment in front of them helps protect them in the event of a front-end collision, but Borroni-Bird said that is a mistaken assumption.
"That 800 pound engine is not really protecting you when you have an accident," he stated, "because its coming at you. So, really, you'd be much better off if that 800 pounds were crushable, like a honeycomb matrix. And that's probably something that we'd want to do is cover the front end of the vehicle, both in the chassis area and also in the body area with an energy absorbing material that would be optimized to absorb crash energy from multiple-directions.
Borroni-Bird believes they will be able to engineer even greater safety into the vehicle than is possible today, not only because you've moved the once lethal engine to below the passenger but also because you've also significantly lowered the center of mass of the vehicle. With most of the weight of the vehicle just a few inches off the ground, he said "you're less likely to have a rollover and you have much better handling of the road when the weight is as low down as possible."
PURE FUEL CELL OR HYBRID?
Because carmakers are learning that there are advantages to a hybridized fuel cell system, one that relies on a combination of fuel cell and batteries or super capacitors, we asked Borroni-Bird if GM was considering this for its "Skateboard" power plant.
He replied that while his team is open to that possibility, the first generation, drive-able test bed vehicle, due out by the end of 2002, will rely solely on the power output of its fuel cell engine. He added that while there are some batteries in the chassis, these are dedicated to providing power for the 42-volt, drive-by-wire system.
"You need some redundancy. You know, if the fuel cell should fail, you need to be able to provide power to the drive-by-wire technologies. So, we'll need batteries onboard the vehicle, but whether they provide propulsion is not clear at this point. We have do the analysis and look at the relative costs by kilowatt and weight and volumes to kilowatt for batteries and fuel cells.
"It may make more sense to have a 50 kilowatt fuel cell and a 50 kilowatt battery from a cost, weight and volume standpoint, than just having a 100 kilowatt fuel cell, for example. We may want to go that path, but we haven't made a design yet."
HYDROGEN STORAGE ISSUES
Initially for the generation one AUTOnomy test bed vehicle, Borroni-Bird and his team will use compressed hydrogen tanks in the Skateboard chassis.
"Compressed hydrogen is the simplest system to use. . . We want to demonstrate the concept of the separate chassis, the drive-by-wire, the interchangeable bodies. We want to demonstrate that aspect of the concept more than the hydrogen, so that's why we're using compressed hydrogen for this first generation."
Borroni-Bird added that as the program moves forward, his team will have to come up with a better hydrogen storage solution, one that allows for greater energy density than is possible with compressed hydrogen. He said the team is also looking at liquid (cryogenic) hydrogen, metal hydrides, chemical hydrides and gasoline reforming.
The first iteration of the AUTOnomy concept will not look like the concept vehicle shown at the 2002 Detroit auto show. Borroni-Bird could not reveal to EV World what the vehicle will like other than to say the chassis will be about twice as thick as the 2020 "stretch" concept mockup. As for performance targets, these too will be very modest, he stated.
"All of our show vehicles have modest performance targets. And with the drive-by-wire system, we have good reason from a safety standpoint. A lot of people getting into a vehicle with drive-by-wire, they're not used to the sensitivity of driving. So we want to limit it for safety reasons as well. But there is no reason why the vehicle couldn't perform better than we're going to let it perform."
"The thing about this concept is, there is nothing in it that is a show-stopper," he explained. GM is using its proven fuel cell engine -- demonstrated in the Opel Zafira fuel cell prototype -- and proven X-wire drive-by-wire technology to make this concept feasible. "We're taking two technologies that have been independently demonstrated and validated with internal combustion engine-type architectures and we're basically combining them. We feel extremely confident that we can demonstrate something by the end of the year.
"Now the challenge is getting that skateboard thinner," Borroni-Bird continued, observing that this means finding a practical way to store hydrogen within the chassis. This necessitates moving the traction motors out of the skateboard and into the wheel, themselves. This will be the challenge for the second-generation version, as well as continuing to shrink the thickness of the chassis towards the ultimate target of just six inches.
Not only does the hydrogen fuel cell engine emit no pollution, only distilled water vapor, the AUTOnomy's drive-by-wire system also promises to be dramatically cleaner than the current system of hydraulic and lubrication fluids of current vehicles, Borroni-Bird pointed out. But the benefits may not end there, he thinks.
"The other aspect that is interesting from an environmental perspective is the fact that we think there is a possibility that this chassis could be extremely durable and long-lasting because there are very few moving parts in the system." He also stated that GM has high confidence that the fuel cell stack also will be very durable. This could translate into a chassis with a lifecycle of 15 to 20 years.
What this may evolve into is a chassis that "grows" with you through your life. A single person could trade in their Cavalier body for a family sedan body when he or she marries and has children. As the family grows, the sedan could be swapped for a minivan and so on. This approach not only lets you change the body style, but again like a computer, you could upgrade the performance package of the chassis.
One of the selling points of having a fuel cell powertrain is the electric power options it offers, everything from powering your home in a emergency to the ultimate recreational vehicle. Borroni-Bird mused about designers someday creating a RV that could venture deep into the wilderness with enough power to light a small community and flat floor space that stretches bumper to bumper. "In terms of developing a new vehicle concept, it offers some real potential here," he told EV World.
FROM HERE TO TOMORROW
While the AUTOnomy concept is exciting, it does face some formidable barriers before it becomes reality. Borroni-Bird ticked off the three biggest: providing sufficient hydrogen storage, reducing fuel cell costs, and creation of hydrogen fueling infrastructure. He said that the first two are the responsibility of companies like GM, but the third has to involve both industry and government. It is important that the industry agree on a fuel standard in order for a hydrogen fueling infrastructure to begin to be built. He added that none of these is explicit to the AUTOnomy concept alone; they impact any fuel cell vehicle.
Assuming carmakers can agree on a fueling infrastructure -- a big IF given the long battle over EV charging technologies -- Borroni-Bird is setting his sights on seeing the emergence of AUTOnomy-based production vehicles by the end of the decade.
"Even if we had all of the technical problems solved this minute, it would probably be five years to get everything validated . . . I am thinking the end of the decade is our target. I think that if we are successful, you would see a transition from a gasoline economy or petroleum economy and a hydrogen economy taking place over a decade or so, from 2010 to 2020.
Borroni-Bird concluded by saying that both public and press reaction to the car at its unveiling has been very positive, adding that GM's management, from the top down, is very supportive of the program. Clearly Borroni-Bird and the team at ATV have created an exciting, hopefully breakthrough technology that will transform the way the world builds and fuels cars in the 21st century.
GM has learned some hard lessons over the last 10 years since the introduction of the original GM Impact, the battery electric two-seater that became the EV1. EV World hopes that experience will not only pay off in terms of new patents and design awards, but in real vehicles available in the showrooms of America and the world.
But it will take technology and manufacturing cost breakthroughs, a massive reinvestment in a hydrogen refueling infrastructure. All daunting obstacles. But perhaps the most formidable challenge of all is getting the car buying public to believe in the necessity for a car like AUTOnomy. If they demand it, car makers will build it. If not, it will only have been an interesting engineering exercise.
Perhaps Buffalo News cartoons Tom Tole summed it up best with this biting editorial cartoon strip.
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