TRW Automotive has one of the broadest ranges of passive and active safety systems of any supplier worldwide.

Passive safety products like airbags and safety belts contributed 23.4% of 2003 sales of $US11.3 billion. Active safety systems, such as electronic stability control, make up just under 10%.

Sales of chassis systems, including steering and suspension, accounted for 21% of sales. Put together, these businesses generated revenues over $6.2 billion in 2003.

But TRW wants to make products from across its divisions work more closely with each other in production vehicles.

Linking systems

One reason is that passive safety systems per se have reached a plateau. "Airbags themselves will improve, but the number of airbags is limited," said Uwe Class, manager for core engineering, reversible systems at TRW. "If you want to achieve improvements further on, you need to go to the active side before collision."

For example, radar data from adaptive cruise control can be sent to a forward-looking camera located in the interior mirror.

This can then analyse the types of vehicles around the driver. At the same time, an occupant detection system can tell which seats are empty or if a very large occupant is present.

In an emergency situation, for example an imminent collision with a large SUV, data from the various systems can be fed to the airbags to tell them which way to deploy to best protect the vehicle occupants.

The new Mercedes-Benz M-Class SUV launches shortly in North America, with a pre-safe system supplied by TRW. Pre-safe includes a reversible seatbelt pre-tensioner called Active Control Retractor (ACR).

ACR uses an electric motor to pull the seatbelt tighter when instructed by sensor input from steering and braking systems. Then if a crash does occur, occupants have a lot higher chance of being in a better position for airbag deployment.

ACR is an early stage of the integration of safety systems, and is not a truly intelligent system. ACR does not know if a vehicle is going to crash, but relies on pre-defined inputs from other systems, which depend on driver reaction.

TRW wants to take integration to another level, where a higher degree of automatic response will be possible.

With ACR, "if the driver's not paying attention, there is no reaction from the braking and steering systems, and no signal input. So [in an integrated system] we would react to the radar signal and do the pre-tensioning," said Class.

ACR was originally introduced in 2002 - in the Mercedes-Benz S-class luxury sedan - and since then there have been only a few small steps taken toward safety system integration.

Obstacles remain

"As a supplier who is ready with the technology, progress is always too slow," said Class, "but the pre-safe system is out there, and has proven to be a real benefit, both in safety and comfort, so it will make its way."

But there are several problems associated with systems integration. While airbags and stability systems improved safety by measurable margins, expensive integration for only an incremental gain is a hard sell.

End consumers are more reluctant to pay for intangible technology. And purchasing departments will remain very wary of sourcing, say, steering, braking and passive safety for one vehicle from a single supplier.

"We will see systems where we have different competitors in the vehicle, and where we have to learn to understand our interfaces and support each other," said Class.

Class said the AUTOSAR initiative will help with this process, by standardizing a base layer of software and connectors for a vehicle's electronic architecture.

Long term vision

And in the meantime, TRW is concentrating on value engineering to deliver improvements that its customers do want. "For the second generation a big focus is on reducing weight, reducing size, and cutting cost is very important," said Class.

The ACR system fitted to the M-Class is around 30% cheaper, lighter and smaller than the first generation, but offers the same level of protection.

The newest electronic stability control systems integrate a critical sensor into the main ECU and cut the number of control units required from three to two.

This reduces the length of wiring necessary, makes the system more robust, and decreases the overall complexity of the vehicle's data and power networks.

But TRW and others are sure that integration is coming closer. "It's really a long term vision, to have good radar and video based sensor input, and if we achieve that we can do a lot on adapting the passive side much better to the kind of collision which will happen," said Class.