Ford, TI opt for the FlexRay automotive safety bus

The battle lines over which electrical architecture to use in "drive-by-wire" vehicles may be redrawn in the coming week, when Ford Motor Co. and Texas Instruments Inc. put their weight behind an already-powerful consortium of automotive and electronics companies. They will join General Motors, DaimlerChrysler, BMW, Motorola, Philips Semiconductors and Bosch Automotive Group in the FlexRay Consortium, bringing FlexRay to the verge of de facto industry standard.

Spokesmen for Ford and TI told EE Times both companies plan to announce their support for FlexRay in the coming week. The news comes on the heels of an ominous statement by FlexRay representatives last week that they will no longer work with the competing TTA (Time-Triggered Architecture) Group to reach a consensus on a common industry standard.

The shutdown of talks means that the two camps will go forward separately and as competitors, with one group at some point likely emerging as the accepted standard. "The standards won't be equal competitors," said Paul Hansen, publisher of The Hansen Report on Automotive Electronics. "Most likely, you'll have FlexRay and another, smaller standard."

The moves by the FlexRay Consortium lay the groundwork for the automotive industry to rally behind its safety-critical bus standard and, therefore, begin building drive-by-wire vehicles, the first of which are expected by the 2006 model year. By adding Ford and Texas Instruments to its roster, the FlexRay group puts itself in a powerful position because it now counts the world's three biggest automakers and three of the largest automotive semiconductor suppliers among its members.

"With the Ford announcement, the FlexRay people have the chips on their side," Hansen said. "In the standards game, there's strength in numbers."

Foundation for innovation

Automakers have been pushing the concept of safety-critical bus architectures for more than three years because they need such systems to endow next-generation vehicles with drive-by-wire technologies, which many automotive engineers see as the foundation for future innovation. In drive-by-wire, engineers sever the physical connections that tie drivers to their vehicles' tires, brakes and engines. Drivers will no longer feel the road through their steering wheels or sense the brakes through the brake pedals. Instead, the movement of their hands and feet will be regarded as messages. The steering wheel, for example, will become a sort of joystick, sending commands for the wheels to turn, but will not do the turning itself. Similarly, the brake and accelerator pedals will serve as sensors, sending commands to the brakes and throttle through a microprocessor. As a result, hydraulic braking and steering systems will be eliminated.

By employing such by-wire systems, engineers hope to simplify the implementation of such forward-looking concepts as adaptive cruise control, automatic lane-keeping and collision avoidance. Using steer-by-wire, throttle-by-wire and brake-by-wire, they ultimately hope to create vehicles that can autonomously take control, employ the forward-looking concepts and avoid accidents without driver input.

But by-wire won't work without a safety-critical data bus to send signals back and forth from the microprocessors to the electric motors that control the steering, brakes and throttle. Safety-critical buses, such as those supported by the FlexRay and TTA groups, enable drive-by-wire systems to operate safely, even though they don't use the traditional safety back-up techniques of hydraulic systems.

The TTA Group's Time-Triggered Protocol (TTP), developed by TTTech Computertechnik AG (Vienna, Austria), meets the safety-critical requirement because it uses a time-triggered electrical technique to ensure there is always a slot for important messages on the data bus. As a result, crucial signals for the brakes or steering gear don't get lost in the data shuffle. The time-triggered method is considered superior to the event-driven methodologies typically employed by CAN (controller-area network) data buses in automotive power train systems.

Similarly, the FlexRay Consortium is also pushing for adoption of time-triggered technology. Its system, based in part on the well-known Byteflight architecture, uses flexible time-division media access time slots for data. It differs, however, in combining time-triggered and event-driven methodologies, which are said to endow it with greater flexibility for manufacturers. GM, in particular, has said that its flexibility is the key to applying safety-critical architectures across a broad range of vehicle lines.

Both of the competing groups have worked hard to draw automakers and suppliers to their sides. The TTA Group's membership has gathered several significant companies, including Audi, Volkswagen, PSA Peugeot, Renault, Delphi, NEC, Honeywell and Austriamicrosystems. Meanwhile, FlexRay, formed in October 2000, has been successful in luring the world's three biggest automakers?GM, Ford and DaimlerChrysler?along with Motorola, the industry's biggest silicon supplier.

Single-standard push

Last fall, the two groups accelerated efforts to merge the technologies to form a single industry standard. At the time, executives from FlexRay said they had quietly set a date of March 31, 2002, for discussions to terminate, so automakers could move forward with their design efforts if no resolution occurred.

Three weeks ago, after a FlexRay International Workshop in Munich, FlexRay executives said they decided it was time to move on. "TTA Group was aware of the time schedule," said Benjamin Baker, director of the Electrical Center for General Motors' North American Car Group (Warren, Mich.). "There were dozens of meetings, and the time frame was all scripted out. But we reached the end of March without any resolution and the management ranks of FlexRay was very concerned about this turning into a protracted, never-ending discussion." Hence the decision to "shut it off from our end." The FlexRay decision may closely follow the moves by Ford and Texas Instruments to join the consortium. Both said this past week they plan to join as associated members. Formal announcements from FlexRay are expected shortly.

Silicon stance

The combination of the FlexRay decision and the announcements from Ford and TI is expected to be a major blow for the TTA Group. TTA Group officials, however, steadfastly held their ground, saying that the announcements were more political than technology-related.

"It doesn't make sense to talk about big company names," noted Georg Kopetz, managing director of TTTech Computertechnik. "It makes more sense to talk about the availability of silicon."

Indeed, the TTA Group announced several weeks ago that it has a communication processor that supports the Time-Triggered Protocol, available through the TTTech Web site. In contrast, the FlexRay Group will not have silicon available until the first quarter of 2004, Motorola officials said.

Still, members of the TTA Group say the lack of availability of silicon isn't an issue when automakers are still several years from introducing by-wire systems.

"We don't think it would make a big difference if we had silicon now," said Andreas Both, FlexRay business and technology manager for Motorola Inc. "Today, car manufacturers are still building prototype vehicles, and there's no reason they can't use prototype hardware for that." Both added that Motorola has introduced a field-programmable gate array for use with FlexRay. The FPGA, he said, was demonstrated at the recent FlexRay Workshop on a prototype FlexRay vehicle.

Still, some industry watchers were wonder whether automakers such as Audi and Volkswagen will buck the rest of the industry and remain committed to the TTP technology.

At press time, Audi did not return calls regarding its plans. Until last week, Audi had maintained that it would stay with the TTA Group because TTA offered the safer of the two technologies.

Observers said, however, that they believe the technologies are very similar and that the issues at stake aren't necessarily related to safety concerns. "It's more a matter of politics and business than it is of technology," said analyst Hansen.

FlexRay representatives said TI's and Ford's decisions are bound to affect other automakers that have not announced a course of action, plus some that have committed. "The companies that haven't decided are going to have to make a decision," said Baker of GM. "But the ones who are really in a tough spot are the ones, like Volkswagen and Audi, who have already decided for TTA."

"The question now is whether Audi will want to be by itself when GM, Ford and DaimlerChrysler are committed to another protocol," Hansen added.

TTA representatives said this week that they were stunned to learn through EE Times' calls that FlexRay had shut off talks. "As a company and as a group, we are still interested in reaching a consensus," said Kopetz of TTTech.

Engineers said that automotive suppliers and OEMs would still benefit from the emergence of a single standard.

? Charles J. Murray

EE Times