GM Autonomy Concept Vehicle Skateboard chassis
The heart of the AUTOnomy concept, the fuel cell-powered "Skateboard" will house a fuel cell, hydrogen storage, hub motors, controls and X-wire technology.

Breaking Convention

Can a concept so bold really get off the drawing board and on the road?

By Bill Moore

Chris Borroni-Bird is a quiet-spoken Englishman with a Liverpool accent that reminds you of the Beatles. He is the program manager for the innovative - - maybe even radical - - AUTOnomy concept vehicle.

One week after GM unveiled this extraordinary concept vehicle at the 2002 North American International Auto Show, Chris spoke to EV World about the program, revealing that his team hopes to have a working first generation version of the vehicle running by the end of this year. And while the mockups shown at the Cobo Convention Center, where just that, mockups, serious efforts are underway to turn plastic and steel dreams into a real working prototype.

Borroni-Bird began our interview with an explanation of how the concept all came about. He began by saying, "We were given the challenge of designing what a vehicle designed around a fuel cell might look like. Up to now every vehicle that has been demonstrated by GM and our competitors have basically taken an internal combustion engine [vehicle] and taken the engine and transmission out and replaced it with a fuel cell and an electric motor and controller. These are very conventional looking vehicles, of course, with graphics on the side saying they are fuel cell-powered."

Instead, the GM team realized early on that fuel cell technology was improving "by leaps and bounds." Because power density was improving, the size of the stack was also shrinking, requiring less and less space inside the vehicle.

"It became possible for us to imagine not only putting the fuel cell stack under the floor, which is what many of our competitors have been doing, putting the whole fuel cell propulsion system under the floor, including the electric motor and controller, so that you get rid of this engine compartment hood that we have today," he stated.

But what really enabled the AUTOnomy concept to evolve was the development of X-wire drive-by-wire technology developed by a Swedish firm, Borroni-Bird explained. By eliminating the need for mechanical and hydraulic linkage between the passenger compartment and the vehicle drive train, it became possible to develop what GM engineers call the "Skateboard," an autonomous, self-contained drive train chassis. [See photo above. Click here for large diagram of Skateboard components].

Integrated into the Skateboard would be the fuel cell stack, power electronics, hydrogen storage tanks, collision absorption materials in the front and rear, along with cabin environmental systems and the X-wire docking system.

According to Borroni-Bird the marriage of fuel cells and x-wire makes a great deal of sense because the drive-by-wire system requires 42 volts to function, which the fuel cell can easily supply.

"Both will be available in the next five to ten year time frame, but we¹re not quite there yet," he added. "We believe that is the future for the propulsion system and chassis respectively."

Not only is there "great synergy" between fuel cells and drive-by-wire, but the combination of two sudden made feasible the notion of separating the chassis from the body of the vehicle. What results is a universal drive platform that could ultimately be just 6 inches thick on which could be mounted a nearly infinite variety of body shapes and styles. While the concept isn¹t new, the technology exists now or will shortly exist to make it possible.

"You¹ve got a clean, flat sheet to work from," he said in reference to the fuel cell chassis. This will enable designers and engineers to someday hopefully exercise their reaches of their imagination - - within reason and safety - - to develop body styles of infinite variety and even individuality.

But design innovation need not be limited to the exterior of the vehicle, he pointed out. X-wire technology will enable radical new interior designs as well. Because it will be possible - - when drivers eventually get accustomed to it -- to eliminate the steering wheel and foot pedals in the car, all sorts of interior layouts can be developed. The driver can sit on left, right or even in the middle if they wish. A person driving a car in Europe where left hand drive is the convention can switch to right-hand drive once they emerge from the Channel Tunnel onto English soil. While steering wheels might still be used, they would eventually be supplanted by a single wrist control or joystick - - something the younger generation is already familiar with.

"What we feel is important about this concept is that it really allows a fuel cell vehicle to be something different than an internal combustion engine."

The change envisioned in the AUTOnomy concept could, conceivably, break the 100 year-old tie with the horse and buggy, because all early automobiles were only motorized carriages. This is a legacy that has saddled the automotive industry for a century. Borroni-Bird agrees with that assessment.

"We strongly feel that if you try to fit an fuel cell into an internal combustion engine architecture that you¹re really not taking full advantage of what the fuel cell has to offer. And you¹re only providing an environmental benefit, which is obviously very important to society . . ." He pointed out that most GM customers don¹t buy vehicles for their environmental benefits, alone.

What we feel is important about this concept is that it really allows a fuel cell vehicle to be something different than an internal combustion engine. To offer a different and better value proposition to the customer, so we can great much more excitement about fuel cell vehicles and get them into the marketplace much more easily than we can if we just put them inside a regular internal combustion vehicle."

By-Wire Becomes Catalyst for Concept

Borroni-Bird told EV World that it was the drive-by-wire technology that proved the catalyst for this radical departure from a century-old design convention.

"Without drive-by-wire, you can¹t hope to have interchangeable body modules," he stated. It is, in his opinion, a "key element of this story."

To begin exploring the potential of the concept, GM¹s engineers are working on a generation one version of the concept that will seek to integrate drive by wire and fuel cell technology. This early prototype won¹t have all the features incorporated into the 2002 NAIAS concept vehicle mockup. For example, in-wheel hub motors will be explored in the second-generation prototype.

However, while some are skeptical about the practicality of hub motors from both a reliability and vehicle dynamics perspective, he is convinced that they offer great promise.

He stated that in order to gain as much hydrogen storage space in the Skateboard as possible, they need to move the traction motors out into the wheels themselves. He said that everyone has looked at hub motors and have dismissed them after a cursory examination.

"We feel very passionately that wheel motors are a very promising technology that really haven¹t been fully explored."

The mockup shown in Detroit last week is what he calls a "stretch" vision for the year 2020. Based on the current state-of-the-art, the best GM can do right now is a chassis that is 10-12 thick instead of one a mere 6 inches in depth. He sees that it could be possible in the near-term to shrink this to 8-9 inches if fuel cell technology continues to progress at its current hectic pace.

If GM can eventually bring this concept to fruition - - clearly a big IF - - customers could expect to someday buy an open skateboard chassis and then pick the body style they want. That body might come from GM or perhaps even small custom manufacturers to whom GM has licensing agreements. One could imagine dozens of regionally-centric manufacturers turning out a few hundred or maybe a few thousand custom bodies a year, employing more entrepreneur-minded UAW workers in employee-owned operations.

A Closer Look At the Chassis

Unlike the mockup, a production Skateboard will, in all likelihood be open at the top for ease of service, Borroni-Bird observed. Since it will be covered by the body nearly all the time, there will be no need for a separate "skin" such as seen in the accompanying photograph.

As for the fuel cell part of the Skateboard, GM is developing its own system rather than relying on an outside vendor like Ballard, which is partially-owned by both DaimlerChrysler and Ford. Interestingly, he stated that fuel cell technology has shrunk by a factor of ten over the 24-36 months, in terms of size for a given power output. This translates into the fuel cell system occupying about one-third of the chassis with virtually the remainder allocated for hydrogen storage.

As to the question of hydrogen storage, GM is still investigating many options, he noted. The generation AUTOnomy prototype currently being developed will use compressed hydrogen at 5,000 psi. However he doesn¹t see compressed hydrogen being the long term solution and he is skeptical about using the newer 10,000 psi tanks inside the Skateboard simply because they will be too large due to the thickness of their walls. He said the same issue affects liquid or cryogenic hydrogen.

Somewhat more promising are liquid and metal hydrides that can store a greater volume of hydrogen, though they also have significant technical and cost drawbacks. One of the advantages is their inherent safety compared to compressed gas. In the event of an accidental rupture of the storage tank, no free hydrogen is released into the atmosphere where it could potentially combust.

Given the size constraints of the Skateboard, it seems a pretty good bet right now that GM isn¹t planning on using its gasoline reformer technology on this vehicle, Borroni-Bird said they hadn¹t ruled it out yet. Instead, he suggested it gasoline reformer technology seems to make a great deal of sense in a stationary application, something we at EV World have begun to advocate as a transition strategy. Gasoline or petrol service stations could be outfitted with either a stationary gasoline-to-hydrogen reformer or a steam reformation system that extracts pure hydrogen from natural gas. Conventional gasoline or gasoline-hybrids could continue to get the fuel they need while the world gradually shifts to hydrogen, eventually generating it, not from non-renewable fossil fuels, but from renewable sources using solar energy or specially-engineered bacteria.

Borroni-Bird stated that GM was working on stationary gasoline reformers, but that like hydrogen storage, this technology, too is beset by numerous obstacles, one of the biggest of which is its long start-up time. So, for the time being, the AUTOnomy team will rely on compressed hydrogen storage, while looking at other options.

One Universal Platform?

GM press releases last week spoke glowingly of the potential of having only two or three chassis styles, which could be used for anything from mini-buses to luxury cars. Borroni-Bird admitted that they really hadn¹t thought that hard about this notion. Like much of the rest of this "dream" vehicle, the company is a long way from realizing that reality.

However, if it could reduce the number of vehicle platforms from the current 11 to 12 GM has in production in North America to three or four, he speculated it could translate into significant cost savings for the company and its customers. If the company could find a way to mass-produce two or three basic Skateboards, it could reduce the cost of fuel cells and finally break the stranglehold of the low-cost internal combustion engine.

The performance of the vehicle can be altered, he explained by scaling up the components. To get more power, you add more plates to the fuel cell stack. The same applies to the power electronics. All of it is quite scaleable, he asserted. Of course, a pickup or SUV chassis would need to be more rugged than a passenger car or minivan design, which necessitates more than just one universal platform.

"Before the AUTOnomy concept came along, we were shooting to have fuel cell vehicles be competitive in price with an internal combustion engine vehicle. And basically that means the fuel cell powertrain has to be the same price as an internal combustion engine powertrain.

With this concept, we feel that if we can get the fuel cell to be comparable to an internal combustion engine powertrain than the vehicle costs can be significantly less with this concept."

For Borroni-Bird this can happen with the economies of scale he sees possible with this new approach. He also believes that development costs can be reduced because of the scalability of just a handful of basic chassis designs that could conceivably have 15-20 year life expectancies. Perhaps a less cogent argument is that because these cars will be so much more attractive in styling and functionality, GM won¹t have to spend so much trying to sell them.

Of course, not everyone is buying into the concept, let along the vehicle. Here¹s a teaser panel from the pen of cartoonist Tom Tole. We¹ll show you the rest next week when we continue part two of our exclusive interview.

Part Two Continued...

Times Article Viewed: 15008
Published: 19-Jan-2002


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