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FlexRay, Ethernet vie for role as safety systems share data

Changes in networking are likely to occur as safety systems are linked together to further reduce accidents and pave the way for autonomous driving. Many developers feel that the bandwidth of CAN (Controller Area Network) systems won’t meet emerging demands, so they’re moving toward Ethernet and FlexRay.

CAN remains efficient for standalone safety systems in current vehicles. While its role will remain in other areas, usage is expected to wane as the industry moves to connected safety systems that work together to provide a comprehensive view of the area surrounding the vehicle.

“Safety systems have generally been quite independent systems, with little networking between the sensors,” said Andy Whydell, Product Planning Manager at TRW Electronics. “One of the keys moving forward for autonomous driving is to network the systems so you can build a picture of the environment around the vehicle, showing anything in the full 360°.”

There’s no consensus on whether FlexRay or Ethernet will become a predominant architecture. Ethernet offers lower costs and ease of use, but FlexRay offers determinism, which can be important in safety.

“A distributed control system will be needed, and it will incorporate the use of time-triggered protocols such as FlexRay,” said Brian Daugherty, Visteon’s Associate Director of Advanced Development and Intellectual Property.

FlexRay was designed for automotive applications, so it’s seeing use in some vehicles now in or nearing production. But it hasn’t been able to build momentum over the past several years, leading many companies to explore Ethernet.

“We’re launching a new vehicle platform, and FlexRay will be part of that,” said Erik Coelingh, Senior Technical Leader at Volvo Car Corp. “Ethernet is a topic we discuss; it’s clearly attractive.”

One of FlexRay’s biggest obstacles is its cost, especially when compared to Ethernet technology. FlexRay’s volumes are still minimal, keeping device prices high, and its complexity drives up development costs.

“FlexRay remains a valid bus, but it seems to have a limited future,” said Davide Santo, Safety and Chassis Segment Manager at Freescale Semiconductors. “One problem is that it’s over-engineered.”

Though Ethernet’s still a rarity on production vehicles, vendors throughout the supply chain are doing a lot of development work with Ethernet. Tier 1s are gearing up for more demanding 360-degree sensors.

“The majority of sensors today have high-speed CAN or FlexRay,” said Kay Stepper, Regional Business Manager for Automated Driving at Robert Bosch Chassis Systems Control division. “Our next-generation sensors have Ethernet built in, at least as an option. Ethernet has bandwidth that high-speed CAN can’t provide, which is especially important when you’re talking about sensor fusion where vast amounts of data must be communicated.”

A number of auto industry vendors formed the OPEN Alliance, which promotes One-Pair Ether-Net, based on Broadcom’s BroadR-Reach technology. Another automotive group, the AVnu Alliance set up AVnu Automotive AVB Gen2 Council to promote the use of Ethernet Audio Video Bridging technology. Chipmakers involved in these groups say Ethernet has some great advantages, augmented by a couple groups that focus on automotive applications.

“Ethernet is scalable to Gbits/second,” Santo said. “With AVB, you can sync nodes and do point-to-point with gateways.”

Ethernet AVB is well suited to cameras, which are key sensors for safety systems. The network can also play a role in interiors, handling the range of infotainment options. STMicroeletronics is bullish on Ethernet’s potential.

“Most likely Ethernet will be used for infotainment and cameras,” said Raffaele Penazzi, New Product Initiative Manager, Automotive, at STMicroelectronics. “Ethernet MAC (Media Access Control) is going to be integrated in the majority of ST processors.”

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