Non-Mechanical Steering

[teroenza]

Hello all,
With all-electric car designs becoming more popular, I was wondering if it was really necessary to have all that mechanical linkage in the front of an automobile to steer. Assuming independent electric motors for each wheel, and drive-by-wire technology, a simple alteration in wheel speed for the wheels on one side of the car could steer it (like tanks and their treads). Wheel speed, steering wheel input, and other data could easily be processed and made into a steering system. Has anyone seen any concept cars like this, or designs promising such a system? Can anyone think of major drawbacks?

[shorod]

The major drawback would likely be public acceptance, or lack of it. Consider how freaked out the media has made the public over this "unintended acceleration" issue of recent Toyotas with the throttle by wire system (which is common in just about every new car). Now try to convince the public that electric steering and throttle by wire will be safe in the same car. I'm also not sure the parking infrastructure would survive a design like tanks use. Seems like parallel parking could be a bid difficult, and it seems like tire wear would be an issue.

The most interesting solution along these lines was in a Nissan concept car, might have been called the City Car. The car could be driven either direction (no need for "reverse" per se) and all four wheels could rotate 360 degrees so you literally could pull up to a parallel parking spot, stop, then pull straight in to the right. Public acceptance would still be an issue obviously.

-Rod

[shorod]

http://www.geekologie.com/2007/10/ni...ept_car_is.php

[RidingOnRailz]

The best place for non-mechanical and electrical PS . . . .

[img]http://www.mnpig.com/minnesota/paint...%2705---01.jpg[\img]



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[jdmccright]

The big roadblock to using all-electric steering is safety. If there were a loss of power, the driver would not be able to steer the car safely to a stop. Granted, one could program a reserve or have a back-up supply of power, but MVSS requires the ability to maintain steering ability even in a complete vehicle power failure.

There is great merit to electrical assisted steering...less weight and complexity. But the main drawbacks so far have been a very numb steering feel and not being tuned right...either too responsive or not responsive enough. Eventually they'll find a happy medium.

But the recent Toyota steering and acceleration issues have made everyone rethink just how far designers and engineers should go to electrifying everything.

[shorod]

Of course someone can always bring up how long the airline industry has been using throttle and steering by wire. Granted the steering in aircraft is typically hydraulic, and the reliability is pretty good there.

For some reason consumers tend to be pretty adverse to major changes. People were afraid of airbags when they first came out, don't want "explosive" hydrogen fuel cells in their cars, didn't like the idea of computers in cars (and revisited the fear just prior to Y2K), etc.

Reminds me of a story that was shared with me when I was interviewing for an engineering job. The company made a transmitter that was in high demand and popular in their market. Due to design improvments, they determined they could make a screw oscillate and no longer needed an antenna mast. When they released the upgraded product, sales dropped. They quickly pinged their prior customers to find out why they didn't purchase the new product. The majority of the customers indicated that they need long range and without an antenna, the new product could not meet their needs (or so they thought). The company quickly designed in a dummy antenna (connected to nothing) and again they dominated the market.

-Rod

[teroenza]

Thank you all for the replies, I did not think of the human psycological acceptance factor.

[RahX]

With rack and pinion, there is basically only one unit to control the steering of the vehicle. A strut suspension with rack and pinion is about as simple as it gets. Not to mention, rack and pinion makes it a lot easier to keep the front wheels in alignment and adjust it if they aren't.

[RidingOnRailz]

Originally Posted by RahX

With rack and pinion, there is basically only one unit to control the steering of the vehicle. A strut suspension with rack and pinion is about as simple as it gets. Not to mention, rack and pinion makes it a lot easier to keep the front wheels in alignment and adjust it if they aren't.

And I know its cliched but..."If they can land on the moon" they can develop a power-steering that fades to zero assist from 20 to 30 mph - preferably on a hydraulic platform.

A lot of cars that get a "5" or "6" from Consumer Guide or such for the Handling/Steering rating category would get a 7 or 8 just by cutting back on whatever kind of power steering assist the car has. When James Healy at USA today remarks that the steering on a 30+thousand dollar car(2010 Acura TSX) is twitchy, and when several magazines comment on the "numbness" of the steering on the last 6 model years of Toyota Camry - that ticks me off. What are these manufacturers thinking? How much assist do they "think" we want?? Did someone interview a dozen retired golfers and determine that they all wanted their Buicks to float and bob over road imperfections, and be able to steer by blowing on the steering wheel? Or the 2005 & up Malibu, with it's early infamous "left pull"?

Automotive steering/handling has progressed immensely in the last 40 years. No longer do we have to turn the steering wheel 4-6 times to go from a left turn to a right. Tires today track straighter than ever. So how difficult is it to get a steering wheel to solidly center from a turn, and stay there without constant correction from the driver? And when the driver does turn, increase the resistance progressively to his turn along with increasing road feedback that he/she has, in fact, turned the wheel(and the vehicle) away from a straight-ahead. In short, how challenging is it to get the feeling represented by my handle(above) in any automobile price range?

Would the mfgs listen if we all e-mailed or snail-mailed or telephoned in these suggestions?

[fredjacksonsan]

While an all electrical steering system is certainly possible, the back ups and failsafes required would make the cost of a vehicle much, much more. It's the same reason that airliners are 60 million, they have all kinds of backup systems, and those systems are also backed up. That costs money...and adds weight.