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."
I really like the mechanical shaft backup system for this design. There is always a chance of an unintended failure and this backup shaft is a good way to mitigate this risk.
Greg, the backup is absolutely required. While it is rare, I have been in a car where the power failed and the power steering stopped working. This was a hydralic system, and it was very hard to steer the car, but at least it could be done. Electrical systems are more likely to go out on a car, I would venture to guess, than the purely mechanical ones. Especially electrical systems that are digital.
You're not alone, Greg. I think most consumers will feel safer knowing the shaft is there, at least until steer-by-wire has a few years of success behind it.
Interesting story, Chuck. It seems that the real gain will come when the redundant mechanical steering is eliminated. Yet that means that you wouldn't have steering if the electrical system failed.
Right, Rob. For now, the clutch is there, but Nissan told us that if the mechanicals were ever removed, its engineers would incorporate a fail-safe sub-system. At this point however, it's not clear how the fail-safe sub-system would work.
I think the only down side is the number of automobiles on the road. The chances of the system failing are far greater than with cars. You cannot guarantee that the car is professionally maintained. However, if this system is fool proof, I mean that with masses in mind, then it is the future.
Today I drive a car with mechanical linkage and electric power boost (by chance, also a Nissan). Nissan propose to give me the same, with an extra sensor and wire to the steering mechanism. The electrical signal will be the primary mechanism, but so what? It doesn't replace the existing linkage. Its extra - extra weight, extra power, extra complexity. What happened to "keep it simple" ? Keeping the mechanical linkage in place as a backup is Nissans' way of saying "we like the new system - but we don't fully trust it"
Anyone remember the accelerating Toyotas? I know GM has been working on this for over 20 years. I think it will ultimately come down to consumers and federal mandates (such as CAFE).
The new 787 Dreamliner is entirely electronic. The difference is the rundundant back-ups are not going to exist in the physical sense on cars (weight, weight, weight). So the development in the automobile has to be sensor/control failsafe that stops the vehicle. It is better to get out of the car that is on the side of the road than trying to parachute out of an airplane with type of failsafe!
I'm going to play teh antagonist here. When it comes to driving, feeling the road is much more important to me than a smooth ride. The feel actually helps me know that a tire has a problem before it is a real problem. I get the whole technology thing for the future, but nothing can replace a solid mechanical system. Removing that is like putting a rocket on the road with no breaks. There always seems to be delay in control system response, and that nanosecond of steering response has saved my life. I embrace technology, but I'm not confident that this is the right way to go.
That is 100% correct. In the aerospace industry there is a massive effort to test and qualify all fly by wire systems to prove that they are fully redundent and fail safe. To incorporate this into a car without a mechanical backup will cause a very complex and expesive system. This is why the aircraft that are relatively inexpesive (single engine puddle jumpers) are still cable and pulley. We may see a day when drive by wire is 100% but I beleive it will be in the high end cars where cost is less of an issue.
Tesla Motors plans to roll out a “compelling, affordable electric car” that will sell for about half the price of its high-profile Model S by the end of 2016, company chairman Elon Musk said last week.
From Dell / Intel® New Paradigms in Design Work Scott Hamilton, vertical market strategist for Dell Precision workstations, 5/2/2013 5
Early in my career, I worked as a draftsman and remember the days of drawing on vellum with numbered pencils and Mylar with plastic lead. This was a fun experience in the sense that I ...
I've been using workstations for more than 10 years and love finding ways to get more performance from my system. With demanding professional applications that require more power each ...
A lasting memory from my first job as an engineer in an auto assembly plant is standing on hard concrete at six in the morning, vending-machine coffee clutched in hand, listening to ...
For industrial control applications, or even a simple assembly line, that machine can go almost 24/7 without a break. But what happens when the task is a little more complex? That’s where the “smart” machine would come in. The smart machine is one that has some simple (or complex in some cases) processing capability to be able to adapt to changing conditions. Such machines are suited for a host of applications, including automotive, aerospace, defense, medical, computers and electronics, telecommunications, consumer goods, and so on. This radio show will show what’s possible with smart machines, and what tradeoffs need to be made to implement such a solution.
To save this item to your list of favorite Design News content so you can find it later in your Profile page, click the "Save It" button next to the item.
If you found this interesting or useful, please use the links to the services below to share it with other readers. You will need a free account with each service to share an item via that service.
Tweet This
40 
