The advertisers were right. That car you're driving is not your father's automobile. It's a large and increasingly complex network of electronic subsystems and components.The transformation reflects a quiet but ongoing revolution in automotive design. Features that not long ago were considered ground-breaking, like automatic braking systems, electronic ignition systems, airbag restraints, and rear-seat video entertainment, are now accepted as standard.
With these features has come a dramatic rise in automotive electronics content. Cars today routinely integrate more than twice the number of electronic components of their predecessors a decade ago. And the trend is accelerating.
While many of the subsystems in today's autos use 8-bit microcontrollers, designers are increasingly turning to 16- and 32-bit chips to meet performance requirements as advanced control systems combine multiple sensors, actuators, and electronic control units.
With technologies like x-by-wire, collision avoidance, intelligent airbags, and high-performance multi- media entertainment on the horizon, the complexity of the electronics infrastructure in next-generation auto designs will increase.
"There are very tangible advantages to new concepts like integrated starter/alternators, drive-by-wire, and electronic valve timing systems," said Finbarr Moynihan, product line manager for 16-bit DSPs at Analog Devices Inc., Norwood, Mass. "But to accomplish those tasks, designers will need higher levels of precision and the increased computational power necessary to control those functions."
How are companies able to cope with these escalating levels of complexity and still contain costs? One way is by managing the growing sophistication of electronic subsystems by improving the communications architecture in automotive designs. Automakers have relied largely on proprietary solutions to link automotive electronic subsystems. But the sophistication of today's systems is driving manufacturers to standardize.
"More and more we are gravitating toward an international consensus about which in-vehicle networks automobiles are going to use around the world," said Paul Hansen, publisher of "The Hansen Report on Automotive Electronics," a business and technology newsletter based in Portsmouth, N.H.
CAN can
The clearest example is the move toward Controller Area Network (CAN) solutions. Originally developed as a cost-effective alternative to expensive and cumbersome wiring looms, the CAN protocol offers carmakers a stable serial communications interface capable of supporting data rates up to 1Mbit/s for a variety of powertrain and chassis controls.
Since the original spec didn't define a physical interface, variations of the bus have emerged to serve different purposes. A fault-tolerant version of CAN, for example, allows for some wiring faults and is now increasingly used in body electronics and infotainment applications.
Over the last several years, the CAN interface has gradually won over many leading automakers. CAN is widely used by European carmakers and, while General Motors, Ford, and DaimlerChrysler have traditionally relied on the slower J1850 bus, they, too, are planning to migrate powertrain and engine controls to the protocol in the next several years.
Strategy Analytics Inc., London, estimates that more than 100 million CAN nodes were built into cars in 2001.
"It's taken about 20 years, but the CAN bus is finally being accepted into most companies as a standard," said Martin Thoone, global director of electronics development at auto components and systems supplier Visteon Corp., Dearborn, Mich.
Low-cost solutions
While the use of the CAN bus is on the rise, automakers are also adopting a multibus approach to cut costs.
"The applications are simply too different," said Michael Schneider, global system marketing manager for the Automotive Segment of Philips Semiconductors, Sunnyvale, Calif. "The requirements for a door lock, for example, are much simpler than for a brake."
While many auto manufacturers have opted for proprietary solutions in the past for slow-speed applications such as window, mirror, and door lock controls, the industry is rapidly turning to a bus subarchitecture called Local Interconnect Network (LIN). The three-wire bus only supports speeds up to 20Kbits/s but is extremely cost-effective.
While new models of the first production cars using LIN--the Mercedes SL and E-class--have only come to market in the last few months, component suppliers expect LIN will be widely implemented in future designs.
"We expect the market to go from a few thousand units today to over a billion in the next 10 years," said Brian Reid, automotive operations manager for 8- and 16-bit MCUs at Motorola Inc.'s Semiconductor Products Sector, Austin, Texas.
Improving safety
Safety is an issue in any vehicle design, and over the past two decades the number and sophistication of safety features has expanded dramatically. But today's standard dual-airbag setup may only offer a hint of things to come.
Automotive engineers are already looking seriously at integrating an array of restraint devices, including side, headset, and rear-seat airbags, dual-stage airbags, inflatable knee boosters, side curtains, and pyrotechnically actuated seat-belt pre-tensioners. At the same time, a bevy of new sensors is under development, including forward-looking infrared and radar sensors and sensors that detect the weight and position of the seat occupant.
If these systems are implemented, the car of the future may be able to detect objects in the road ahead and alert the airbag system to lower its impact threshold in a crash. At the same time, new restraint systems, with airbags inflating in the front, rear, and side, would be so comprehensive they would create what automakers describe as a safety cocoon for the passenger. They would also add intelligence to react to events like a rollover by igniting different airbags or restraints at different times.
"Normally, if you had one or two airbags, you could handle it with a CAN network," said Philips' Schneider. "But the complexity of the airbag system is growing so fast that you need a separate bus system to run it."
One group looking to tackle this problem is the Safe-by-Wire Consortium. Led by Autoliv, Delphi Automotive Systems, Motorola, Philips Semiconductors, Special Devices, and TRW, the group has proposed a two-wire, twisted-pair copper bus that operates at up to 200Kbits/s. One of the most attractive features of Safe-by-Wire is its ability to transport both data and power over a single bus.
A competitive two-wire bus architecture for airbag systems has also been proposed by Bosch, Siemens, and Temic. And BMW has developed a production system of its ByteFlight bus for one of its vehicles.
Eliminating hydraulics
Perhaps the single most exciting area of innovation in car design over the next several years will come in the development of x-by-wire systems. While today's automotive braking and steering systems rely on physical connections and hydraulics to transmit the operator's intent to the wheels and engine, x-by-wire sends commands to the brakes or throttle through a microprocessor and electronic actuators.
New x-by-wire technologies promise to simplify the implementation of concepts such as adaptive cruise control, automatic lane-keeping, and collision avoidance, and lay the groundwork for vehicles that eventually can drive themselves.
The foundation of these innovations will be a high-bandwidth bus architecture able to meet strict requirements for fault tolerance. Safety-critical systems like steering and braking must interact seamlessly and reliably.
The potential market is huge. Analysts at Allied Business Intelligence Inc., Oyster Bay, N.Y., estimate that drive-by-wire subsystems will become a $22 billion business by 2010.
As an event-driven bus, however, CAN can't supply the fault tolerance or bandwidth needed for next-generation x-by-wire applications. Accordingly, a consortium of vehicle manaufacturers and suppliers has thrown its support behind a time-triggered bus architecture dubbed FlexRay.
By allowing important messages to supersede less critical ones, FlexRay provides data rates up to 10Mbits/s and the redundancy that automakers have traditionally deployed with hydraulic systems. Many car manufacturers envision FlexRay replacing CAN in future powertrain and chassis applications.
Philips Semiconductors expects to deliver the first physical-layer silicon for FlexRay this year, while Motorola is slated to announce its first FlexRay microcontroller in 2004. Production vehicles using FlexRay are not expected to come to market until 2006.
Overwhelming bandwidth
While networking requirements for powertrain and engine controls are growing, their bandwidth requirements pale in comparison to the changes taking place in infotainment. Navigational devices, telematics, rear-seat video, and a host of new multimedia products promise to overwhelm the capabilities of CAN and other communication bus architectures.
"What we're seeing in applications like telematics is the convergence of everything from GSM and wireless technology to text and voice recognition all combined in a sophisticated user interface," said Analog Devices' Moynihan.
To support those emerging applications, Analog Devices is packaging its BlackFin family, a line of 16-bit DSPs co-developed with Intel Corp., for automotive multimedia applications. The new DSPs use a single-instruction-set architecture that combines the signal processing advantages of a DSP with the control properties of a traditional microcontroller.
However, the data transfer rates required to support the anticipated avalanche of digital data calls for an entirely new bus architecture. To help facilitate the development of these emerging audio and video applications, suppliers are working together through the Automotive Multimedia Interface Collaboration (AMIC), an industry group that includes 12 of the world's largest auto manufacturers.
The group has endorsed a number of bus specifications, but initially much of its support has fallen behind the Media Oriented Systems Transport (MOST) bus. Developed by a consortium led by BMW, Becker Automotive Systems, DaimlerChrysler, and Oasis Silicon Systems, the fiber optic bus supports data rates up to 25Mbits/s. Automakers, including Audi, BMW, and DaimlerChrysler, have already begun incorporating MOST technology into production vehicles, particularly in high-end models.
While the majority of telematics and multimedia systems going into cars today are specifying the MOST bus, there is also significant support for a bus based on the 1394, or Firewire, standard. Companies have spent several years developing a specification for IDB-1394, a version of 1394 designed to meet stringent automotive EMI and temperature requirements.
The latest specification released by AMIC supplies performance and design specifications for both MOST and 1394- compliant platforms.
The argument for 1394 is its ability to scale to higher bandwidths and the fact that millions of consumer products, from camcorders, PCs, printers, and scanners to video games and mass storage devices, already adhere to the specification.
Wireless wave
Not all the bus architectures used for automotive infotainment will be hard-wired, however. "We're starting to see a lot of competition from the wireless side, with buses like Bluetooth and Wi-Fi, or 802.11, where you can exchange data at very high speeds without needing a wire or connector," said Bob Schumacher, general director of wireless products and mobile multimedia at Delphi Delco Electronics Corp., Kokomo, Ind. At the Consumer Electronics Show earlier this month, Delphi showed a production Bluetooth implementation in a Saab 2003 Model 9-3.
Automotive supplier Visteon also recently brought its MACH Voice Link to market in production versions of the BMW, a Bluetooth-based voice activation system that recognizes more than 100 basic commands using speech recognition.
"If you had a Bluetooth connection on your Palm Pilot, you could automatically transfer an address to the car navigation system and have your route planned and be guided to your destination," Visteon's Thoone said. "Or, if you put your private vehicle preferences in your PDA, you could have your seat position, audio preferences, and telephone book automatically transferred into the vehicle's system without touching a connector. In the end, the best solution is no cables at all."
