Taking a page from the world of aviation, Nissan Motor Co. plans to enter the "by-wire" world and control the steering of a future Infiniti vehicle with electronic signals.
The decision to bring steer-by-wire to a production vehicle is a major one for the automobile industry because it lays the foundation for eventual elimination of the mechanical components that now connect the driver to a vehicle's tires.
"There are a lot of advantages to this," Infiniti spokesman Kyle Bazemore told Design News. "It enhances the driving experience. And in the future, after consumer acceptance of the technology, we could theoretically do away with the mechanicals and save the weight."
Nissan's next-generation steering employs a steering angle sensor at the steering wheel, three ECUs for control, electric motors to power the rack, and a steering force actuator near the driver to retain the vehicle's "steering feel."
The next-generation steering system, as Nissan calls it, works by endowing the steering wheel with sensors that read the desired steering angle. Data from the sensors is sent to one of three electronic control units (ECUs), which activate electric motors on the vehicle's steering rack. In contrast, conventional steering uses a direct mechanical connection to the rack-and-pinion.
In truth, the new Nissan system won't eliminate the mechanical connection to the driver. Instead, it will use the mechanical connection as a redundant system, only in cases of extreme emergency. If, for example, a power supply conks out or all of the ECUs fail, it will employ a back-up clutch to mechanically connect the steering wheel to the tires. "The clutch is disengaged 999,999 times out of a million," Bazemore told us. "But the steering shaft is still there, just in case."
Nissan said steer-by-wire will enhance the driving experience. When it reaches the market late next year, it will eliminate some of the vibration from rough road surfaces and it will minutely adjust tire angles to compensate for crosswinds and sloped surfaces. At the same time, it will enable drivers to "feel" the road. Grip information, such as slipperiness, will be transferred back to a steering force actuator that will allow the steering wheel to retain some of its original feel. "Theoretically, you could have no steering feel at all, but that would not be good for drivers," Bazemore said. "That's why we dialed some -- but not all -- of the steering feel back into the system."
Remember when we had the emergency brake? - now it's just a parking brake.
Do you know how long they had the crank after the electric start came out?
How often does a tie rod break - there IS such a thing as inspection.
The mechanical backup defeats the purpose of steer by wire almost completely. It is just a way to introduce it to the skeptical customer. It will be gone in sort order.
I agree. Where's the improvement in this? Aircraft control systems use double and triple levels of redundancy and go through years of testing to please the controlling agency (FAA) before they're allowed to go forward.
This almost crosses the line into the catagory "Technology in Desparate Search of a Use", like keyless ignition, voice commands, digital bathroom scales, etc. Maybe Design News can start a new blog of that title to go along with Sherlock Ohms and Made by Monkeys.
IMHO this is just another monumentally bad idea from carmakers, who seem to believe today that electronics make everything better. Wrong!
There already exists electric power steering systems in many cars at various price points, but it's for assist only (or for automated parallel parking). The low end cars I've driven with this ( a Saturn Coupe we used to own ) had practically zero steering feel and was miserable to drive. When it failed the steering was way over boosted to one side and not at all to the other, creating a very unsafe situation. BMW, according to a recent Car and Driver article, has produced a system that may be subjectively better than hydraulic assist, but it took years for them to get the algorithms right and they can charge what it costs to get good performance. I can only assume there is a similar failure mode.
Auto designers are forgetting that driving is inherently risky and should not be too comfortable, or too easy, or too much like riding your recliner while playing with your latest electronic gadget. I dread the day I have to replace my '04 RSX, because any new car available by then and in my budget will not be worth driving due to the excess electronic control interfaces.
The reasons in the article for switching to steer by wire are:
1. Elimination of mechanical components (what's the advantage of this, other than weight savings?)
2. Weight savings
3. Elimination of vibration from the road surface (no, you will still feel vibrations, and mechanical steering could be dsigned to "eliminate" vibration, too)
4. Minute adjustment of tire angle to compensate for wind and sloped roads (I suspect that the driver will still have to do at least some of this)
5. Enable drivers to feel the road (we can with a mechanical system)(this conflicts with 3, above)
6. Enable auto manufacturers to readily change the design/configuration of cars (e.g. change a left-hand drive car to a right-hand drive car)
There are other motivations for changing to steer by wire. These may include ease of implementation of driverless cars in the future, or cars that drive themsleves when necessary to avoid accidents, and the desire by manufacturers to add gimmicks that will inrease the prices of cars and increase manufacturers' revenues.
A simple mechanical system, even without power steering, is reliable, simple, and inexpensive. This is what I want in my car, not a lot of expensive-to-replace-when-it-fails electronics.
I agree, the clutch would be electrical. But for fail-safe, the clutch would have to be held 'disengaged'. Meaning if a power fail occured the clutch releases, in theory. But, this does not cover failures other than power fail.
Add me to the "no" list. I know the system could perform wonderfully, but it could also fail spectacularly. The hydraulic assisted system in use today still operates, albeit with great effort, in the event of a complete hydraulic failure, and steer by wire would not be capable of that.
On most posts this bulletin board leans towards technology at the expense of increased risk. Autonomous vehicles don't frighten most Design News readers, so I'm a little surprised, and encouraged by the negative response to steering by wire.
I have had nothing but bad experiences with computer control of everything from turn signals, headlights, antilock brakes and smog control systems in my Chryslers. Why anyone in their right mind would want to drive a car "by wire" is beyond me. It is just a bunch of "Microsoft moments" (blue screen of death) waiting to happen at the worst possible time. I prefer my vehicles have the least amount of "points of failure" as possible.
The basic function of a vehicle is stop/go/turn. That's it! Everything else is bells and whistles. At 60 mph, two things I don't want failing; stop and turn. Survivability goes way down if those systems fail. 'Go' is a snug third. I had a Ford Escort and going through an intersection; there were dips on each side of the intersection as you crossed the intersecting road. The engine stopped running after going through the second dip. I was able to steer to the side of the road and stop; parking legally. The problem was traced to a pin in a connector; the pin broke off at the wire crimp. The whole incident was minor. But if the steering or brakes had been lost things could have been much worse. The car I have now is 'go'-by-wire. The jury is still out on that one but it appears to be hung at the moment.
The steer-by-wire might have a niche market such as applications where a steering wheel is difficult or impractical (example, handicap). When I read these announcements, I pause and give thought what they are saying. Example: Nissan states that '... the advantages are ...'. But they never mention the disadvantages. There are always disadvantages. Red flags: '... the clutch is disengaged 999,999 time out of a million.' If a system is disengaged for that long, what guaranties that it will work when needed? How will you know if the backup has failed? Is it ever tested?
The car is not an airplace and its maintanance does not fall under rigorous training and scrutiny.
First we hear of throttle by wire systems that won't allow heel and toe downshifts and now steering systems that isolate direct steering effort feedback and recreate a subset of the available feel. Its clear during my commute that there are many people that are absolutely ready for the driverless car (cell phone in one hand, cigarrette in the other, what's on the steering wheel?) but for those of who find joy in driving there are dark times coming.
I agree with all the comments. I asume the clutch will be run electrically, so a massive power failure may be an issue as well. I like my mechanical steering.
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