Published on December 4, 2013

By-wire age is coming; what's missing is trust

Lindsay Chappell, Crain News Service
Nissan Motor Co. Ltd. image
Steer-by-wire systems replace hydraulic lines and mechanical connections with electronic motors and sensors.

DETROIT (Dec. 4, 2013) — Gingerly, the auto industry is stepping up the push for car features that work by electronic impulses instead of metal pumps, pinions and cylinders.

The motivation is clear: Vehicle technologies lumped together as "X-by-wire" — brake-by-wire, steer-by-wire, drive-by-wire — promise to make cars lighter, safer, easier to build and more fuel efficient.

But selling that point has been tough.

While the technology has been advancing for at least 20 years, its progress has been impeded by consumers fearful of runaway cars and luxury owners persnickety about unfamiliar driving sensations. A recent lawsuit against Toyota Motor Corp. successfully used a "ghost in the machine" argument to turn a jury against Toyota's use of throttle-by-wire. The argument questions whether safeguards and regulations can protect a driver from the occurrence of software glitches.

Those concerns have restrained the industry's zeal for X-by-wire.

Until now.

Powerful global industry factors, such as the mandate for better fuel economy and the competition for emerging markets, are stimulating new interest by auto makers in X-by-wire systems. Not least among them is the new industry race for self-driving vehicles, which proponents say is impossible without X-by-wire.

Nissan Motor Co. Ltd. image
Traditional steering systems offer a mechanical linkage from the steering wheel to the tires.

On the very near horizon are advances in electronic braking that will make inattentive drivers safer, electronically controlled gear shift systems that will keep the most inexperienced drivers from stalling their cars, adjustable chassis to compensate for inferior road conditions, and tunable steering systems that give luxury drivers and enthusiasts more control over the driving experience.

"These technologies are gaining traction," reported Robert Beaver, chief engineer for brake maker Continental Teves' North American vehicle dynamics business. "Customers are lining up for them. There's a big movement for new solutions."

Conti and other technology giants have been working for years to move the market on X-by-wire auto systems. In the past few years, the biggest area of growth has been among electric cars and hybrid vehicles, including the Toyota Prius and the Lexus CT 200h, which use a shift-by-wire transmission.

Conti engineers are developing a brake system with the internal name "MKC1" that will reach the market in 2018. The company declines to reveal what vehicles are scheduled to receive it. But it will give Conti customers in Europe and North America smaller, lighter, electronically controlled brakes that do not use a vacuum pump—a standard building block of traditional mechanical brakes.

"Until now, we've been putting brake-by-wire on hybrids and electrics," Mr. Beaver said. "We're going to start putting them into standard gasoline vehicles.

"We're going to see a drastic reduction in the number of parts in the car as we move into wire systems," he added, referring to X-by-wire concepts in general. "There won't be vacuum pumps anymore. Power steering pumps are going to disappear, and we're going to electric steering."

It's not that removing pumps makes for an inherently better vehicle. It is that auto makers desperately want to improve fuel economy on the coming generation of vehicles. And that means ending the standard engineering practice of running various pumps off of engine power, like so many extension chords plugged into a wall socket.

Fewer devices draining power from the engine means better fuel economy.

Brake, clutch by wire

Competitor Robert Bosch GmbH is on a similar track with an electronic brake system it plans to introduce under the name iBooster. Bosch is also preparing to begin supplying a clutch-by-wire system called the eClutch.

The iBooster will improve energy efficiency on electric and hybrid vehicles by using an electric motor to boost braking power in place of a vacuum pump, said Bosch technology spokesman Udo Ruegheimer.

By building up braking pressure in a third of the time required by a traditional system, iBooster enables a more instantaneous brake response, which will be the foundation for an autonomous-drive vehicle.

Bosch's eClutch allows drivers of stick-shift cars to smooth out the engine surge of rpms between gears, which promises to improve fuel consumption by about 10 percent. Using sensors to monitor engine acceleration and deceleration, it anticipates gear changes, allows drivers to start in second gear from a standing stop, and dispenses with some clutch work while driving.

The by-wire technology also prevents engine stall. An eClutch car will continue idling when stopped, even if the driver fails to put his foot on the clutch pedal.

That feature lends itself to emerging markets, which tend to favor small manual-transmission vehicles. The technology should prove attractive to inexperienced drivers in stick-shift cars, as well as commuters facing the stop-and-go clutch-work of heavy traffic congestion, Mr. Ruegheimer said. It allows auto makers to program the same by-wire clutch system to use in different vehicles.

"You give the clutch the characteristics you wish through the software," he said. "It can have one characteristic in an American sedan, and another for an Italian racer."

Infiniti steer-by-wire

This summer, luxury marquee Infiniti introduced steer-by-wire as an option on its new Q50 sedan. Nissan developed the system internally and markets it as Direct Adaptive Steering.

Infiniti market planners have mostly promoted the feature as a luxury innovation. Because the steering is governed by software settings rather than mechanical pumps and shafts, drivers will be able to scroll through settings on the car's touch screen to select the steering feel they want for any particular drive. One steering setting might be attractive for performance driving on an isolated stretch of country road. A softer setting might be preferable for driving slowly through a crowded shopping mall parking lot.

But Infiniti also said steer-by-wire addresses driving safety.

"By eliminating the mechanical losses that can dull the responses in conventional systems," the company's marketing material reads, "steering response is faster and vibration at the steering wheel is eliminated."

The hybrid version of the Q50 includes Direct Adaptive Steering as standard. To obtain the system on a gas-powered Q50 requires the purchase of a deluxe tech package that costs $5,000 but includes other features.

The new technologies might help simplify vehicle development in the future. But they are certain to come with higher retail costs. Because of current safety regulations, most of them require backup components, which means redundant parts.

Fewer parts, less weight

Clearly, diverse issues are breathing new life into the technologies. Among them:

• Wire-based driving systems themselves require fewer moving parts — aside from the requirements for redundancy. A steer-by-wire system directs the wheels primarily through an electrical wire, controllers and a software system, reducing or eliminating the need for hoses, belts and fluids.

Having fewer parts would simplify a vehicle's manufacturing process. It means it is theoretically easier to design it into a vehicle model — and easier to design it into a list of other models an auto maker might want to spin off of the same platform. That means potentially lower development costs.

The industry's general feeling is that there always will be regulatory requirements for some form of safety-system redundancy. But future redundant systems will be simplified and pared down to fewer parts.

• Having fewer parts also translates to reduced vehicle weight, which appeals to auto makers straining to meet fuel economy targets.

• Programmed microprocessor-based electronic safety systems can react to road issues in a fraction of the time it takes a driver to respond. That, in turn, helps prepare consumers for where the auto industry wants to take them in the coming decade: to autonomous-drive vehicles capable of stopping, turning, swerving and accelerating with no human input.

"The industry has no choice but to go to X-by-wire," said Egil Juliussen, principal analyst for advanced driver assistance systems at IHS Automotive. "It has had some problems getting started in the past few years.

"But now it's a different issue. You can't achieve autonomous driving vehicles without steer-by-wire and brake-by-wire."

The industry has been ballyhooing such technologies since the 1990s. And indeed, one piece of it—"throttle-by-wire"—already is widely accepted. Most new cars now accelerate according to electronic impulses received by throttle-position sensors instead of wires and valves.

But applying that same science to braking and steering has been a bit more challenging.

Mercedes' retreat

Mercedes-Benz A.G. blazed a trail into brake-by-wire a decade ago, with a system on its flagship E class marketed under the name Sensotronic Brake Control. But after it caused complaints and recalls—mostly stemming from Mercedes owners' fears that the system too often failed and kicked on the car's more sluggish mechanical backup system — Mercedes scrapped the technology and fell back onto traditional brakes.

Lexus uses a version of brake-by-wire in its low-volume LFA, although few consumers will ever see it. And the current Lexus CT 200h hybrid has luxury-class drivers changing gears by shift-by-wire. But that technology reached Lexus only because it was already engineered into the car's Toyota-brand version, the Prius. A Lexus spokesman declined to say whether the technology might spread into other Lexus models.

But even the widely used concept of throttle-by-wire has had its problems. Just last month an Oklahoma jury awarded two plaintiffs $3 million in damages in their case against Toyota. Lawyers successfully cast doubt on the safety of the electronic throttle system of a 2005 Camry without specifically proving that it caused the car to accelerate out of control in 2007, killing the driver and injuring a passenger.

Last year Toyota moved to settle hundreds of other lawsuits about allegedly out-of-control throttles, agreeing to pay $1 billion.

Mr. Juliussen said that the challenge to adopting more X-by-wire solutions in the coming decade is the same as it was a decade ago: Consumers have to be reassured that the systems work and can be trusted.

"There's no question that X-by-wire technology will bring all sorts of benefits to the industry," he said. "But auto makers will really have to work hard at making sure their customers are willing to come along with them."


This report appeared on, the website of Automotive News, a Detroit-based sister publication of Tire Business.


Loading Comments Loading comments...