Auto Manufacturers' Drive to Simplify

For consumers, hybrid powertrains mean better gas mileage. For electrical engineers, they mean more controllers, more connectors and more wires.

And more headaches.

"A hybrid has an inverter and the inverter needs a controller," says Robert Schumacher, general director for advanced products and business development at Delphi Electronics & Safety. "It also needs a supervisory controller to tell the inverter and the engine what to do. And it needs a controller for the dc/dc converter and another one for monitoring the battery. Each of these (controllers) has a box and a big connector and a power harness and a signal harness. That's the way you do electrification today."

For automotive engineers, the challenge lies in the fact that most hybrids are being built atop existing vehicle platforms. That, in turn, means that all of those new components must be layered atop pre-existing electrical architectures.

Still, we've yet to mention the really challenging part of this electrical design task: Many vehicles, it seems, were already reaching their limits in terms of microcontrollers (MCUs) and wiring before hybrids began to proliferate. For years, vehicles have used microcontrollers as the brains for virtually every major system including engine, transmission, air bags, instrument clusters, radio, braking and stability control. And that's just the beginning. In addition to those systems, which generally use 32-bit MCUs, today's vehicles are also employing 8-bit processors to control the power steering, ignition, horn, headlights, seat motors, turn signals, dome lights, DVD players, window lifts, heating, cooling, compressors, pumps and tire pressure management systems, to name just a few.

The result is a wiring nightmare for automakers. Vehicle engineers now must contend with 35 to 40 electronic control units (ECUs) on an average vehicle and up to 80 in luxury cars. Moreover, the typical mid-size contains between 45 and 70 lb of wiring. And the numbers are expected to rise as vehicles migrate toward hybrid propulsion systems.

For engineers, the problems with all this complexity are twofold: cost and potential failures. "We're right up against the limit right now," says Chris Thibodeau, director of global technology for electrical/electronic products at General Motors Corp. "We need to find unique ways to integrate features and functions, and still give our customers what they want without overloading our controllers."

Electronic Solutions

Tier-one electronics suppliers and semiconductor makers are trying to help automakers, but solving the problem isn't easy. Electronics technology is moving so fast that it's difficult for OEM engineers to keep up with it. As a result, automakers and suppliers need tighter cooperation than ever.

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"Carmakers are more involved in terms of what they want from an electronics standpoint today," says Amrit Vivekanand, director of business development for   Renesas Electronics America, a semiconductor supplier to the auto industry. "With infotainment and safety systems, they're dealing with model years that are further out, so they're looking for electronic products that haven't even been made yet. For us, it's a matter of modifying product development that hasn't happened yet."

Semiconductor suppliers are encouraging automakers to consolidate. In many cases, they're telling them to employ fewer microcontrollers. In their place, they're suggesting more dual-core MCUs and more Flash memory. Those products, they say, could enable a vehicle's electrical architecture to handle applications that have reached two or three megabytes in program size.

"If you go back 10 years, 32K and 64K of Flash on the chip was enough," Vivekanand says. "Today, even an 8-bit micro needs 256K of Flash. Thirty-two bit processors need one, two and even three megabytes of Flash."

Automakers and tier-one suppliers haven't moved toward dual-cores in a big way yet, but semiconductor makers say that time is coming. "Oftentimes, events in a vehicle require quick responses, and you want to be able to handle more than one of those events at a time," Vivekanand says. "You don't want your micro to be off doing something else when a critical event comes in."

Consolidating Domains

The reason for moving to dual-cores and higher Flash sizes is simple: Automakers need better and faster devices that will enable them to consolidate more functions into fewer electronic modules.

In today's architectures, modules are located all over the vehicle. Engine controls, for example, are tucked under the hood. Transmission controls are on the transmission, cockpit controls are mounted on the firewall and safety modules tend to be located near sensors.

But automakers want to be able to consolidate modules, either by geographic zones in the vehicle or by domains. Delphi, for example, has developed a Linux-based computing platform to consolidate the computing for a color reconfigurable cluster, center console display, voice recognition system, and telematics system that uses Wi-Fi to connect to an Android-based smartphone set-up. The company says its Linux-based platform also offers the headroom to allow for incorporation of active safety systems, such as collision warning.

For hybrid vehicles, Delphi has also developed a product called the Power Box. A self-contained hybrid propulsion system, the Power Box fits behind a vehicle's rear seat, incorporating a hybrid control unit motor controller and battery management controller, along with a 120V lithium-ion battery pack, traction inverter and dc/dc converter. Shanghai Automotive Industry Corp. (SAIC) in China recently used the Power Box to convert a four-door, medium-sized, gasoline-burning vehicle into a hybrid.

Schemes such as the Power Box are more appealing to automakers because they can bunch control systems as part of a domain, rather than as part of a geographic zone. Using such strategies, suppliers say they see opportunities for automakers to eliminate multiple processors around the vehicle. Microprocessors for motors and pumps, for example, can easily be grouped together.

"In many cases today, you've got one micro per pump," Vivekanand says. "But you can integrate those functions into one module and have one powerful micro controlling five pumps. It's not an issue to do that."

For automakers - who typically scrape to save pennies per vehicle - the bottom line is cost. "It can be a dollar or two," says Thibodeau. "But we've seen studies that show it can be up to $10 per car."

Simulating the Changes

Integrating and testing those resulting systems, however, is no simple task.

"One of the big problems for OEMs is how do they make sure all these modules from different tier-one suppliers will play together nicely?" Vivekanand asks. "It's a real challenge. It can push the vehicle launches farther out and cause a lot of finger-pointing."

Tier-one electronics suppliers, such as Delphi and Visteon, are helping by providing software models that show how a proposed electronics architecture might work. In a door module, for example, a software model might simulate the operation of a window lift motor, a door lamp and a door lock, thus allowing engineers to see if there are any conflicts between them.

One such product, Delphi's eScout, allows engineers to simulate the operation of a vehicle's entire electrical architecture. Delphi employed eScout in the design of an electrical architecture for an unnamed automaker, reducing its microcontroller count from 40 to 10, while cutting electronics cost by 35 percent and reducing the number of modules, connectors, power supplies and wires.

"It shows you where the computing centers are and identifies all the signal wires and power wires that run between the boxes," Schumacher says. "It tells you the number of wires and the number of pins on the connectors. It even keeps track of all the signals for the features and functions, and tells you what the high-level architecture looks like."

Automakers are also employing modeling software from companies such as The MathWorks. During the development of the Chevy Volt, GM engineering teams employed model-based design and simulation in the prototyping of the propulsion and battery management systems, even as the technology was barely emerging from the research stage.

"We progressed on the Volt's development without having the battery technology in place yet," says Karla J. Wallace, senior manager for electronics engineering, integration and software at GM. Wallace says that GM started modeling with Simulink, then graduated to Real-Time Workshop Embedded Coder to create the C code that went into the Volt's electronic control system.

For automakers, however, an equally important set of solutions lies in common efforts shared by the entire industry. Autosar (Automotive Open System Architecture), an industry standards group, helps car manufacturers by providing standardized hardware and software interfaces for exterior lighting, mirrors, seats, anti-theft systems, defrost controls, remote keyless entry, parking distance control and numerous other electronic features. Members of the organization include BMW, Bosch, Continental, Daimler, Ford, GM, PSA Peugeot Citroen, Toyota, Volkswagen and dozens of suppliers.

"When you have an industry standard such as Autosar, you can learn from others in the industry," ?Thibodeau explains.  "Having standard hardware and software interfaces across all the controllers allows us to partition our systems more effectively."

The Road to ‘Up-Integration'

For automakers, the road to electrical simplicity is expected to be a bumpy one. The reason: It's easier for them to simplify a vehicle's architecture while designing from scratch. Laying new features atop old ones, they say, makes integration extremely difficult.

"Features sometimes take us by surprise," Thibodeau says. "We try to integrate them as fast as possible in order to be competitive, but we may not always be able to do it in the best possible way. We usually look to improve it in the next go-round."

The goal, however, remains. Automotive engineers know that "up-integration" is inevitable and efforts to improve electrical architectures will continue for a long time, especially as new vehicle platforms are introduced.

"If you ask automakers what their most difficult task is, they'll all say that it's wire-routing and making connections. ?We can all do better. The trick is doing it in an elegant and sophisticated way," Thibodeau says.