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Captain Hybrid
Steer-By-Wire to Reach Production Vehicles
11/28/2012

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.'
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."

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Toaster
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Silver
Prelude to Automation
Toaster   5/12/2014 10:48:27 AM
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I think this a prellude to driverless cars. The more you disengage the driver from the mechanics, the easier this becomes. You have to get people used to the idea that the car will steer or do other things without the actual "feel" of the driver input. "Enhancing" the feel of the car, is rubbish. Take away the power steering, now that is "feel". Drive by wire is necessary for automated robotic driving. Personally? not for me.

ragtoplvr
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Gold
resale value
ragtoplvr   2/4/2014 10:46:50 AM
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We are reaching the point where when a car gets a few years on it, what is a relatively minor failure now, like a power steering rack or a brake booster, will be so expensive to repair it effectively makes the car a total loss.  This will adversly affect resale value.  As an example, take a  common 2002 to 2005 Buick LeSabre.  The Limited with all the bells and whistles, often can be had for the same or less than the much simpler custom trim version.

 

patb2009
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Gold
Re: Mechanical Backup
patb2009   2/2/2014 6:42:27 PM
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You could look at going to a centerstick, side stick system like the X-15 used.

Have the center stick be the computer driven controller but you can reach over and yank on the side stick to get some steering inputs, and if it's over on the side it may package up nicely especially if it only needs a relatively small movement.

Stirwelder
User Rank
Iron
steer by wire
Stirwelder   1/29/2014 11:20:36 AM
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I first saw an electric power steering system implemented in an advanced prototype my employer was asked to simulate in 1978 or 79. The design had a hollow armature servomotor driving a ballnut on a ballscrew rack that went thru the center of the motor to assist in steering and sensed the need for assist just as a hydraulic system does, by sensing the windup of a torsion rod at the pinion. It was an electric servo instead of a hydraulic servo. It seemed to work just fine, although if you turned the wheel rapidly you could feel the inertia of the servomotor.

My concern then was that the mechanical backup mode operation required backdriving the servomotor thru the ball screw-nut. That is fine when it is new, lubricated and smooth, but if the screw or nut has fatigue damage, corrosion and or contamination it would still probably work OK under power but it might not manually backdrive at all. To my knowledge, the hydraulic system doesn't have a failure mode that locks up the rack and pinion precluding manual operation.

That concept was a very compact affair, but it seemed to have a fatal flaw. I wouldn't want it in my life. How does this system deliver power assist from servomotor to the rack? Not much engineering detail given. Not in fashion.

 

dstroz
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Iron
Examine failure modes
dstroz   1/29/2014 9:18:59 AM
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Having experenced a failure of ABS the dealer told me could never happen, drive by wire scares the hell out of me. My ABS on a GM product would wait untill travling more than 32 mph before totaly disabling all brakes. I don't believe the automakers are willing to dedicate the necessary resources to developing the same safty protocals the aviation industry has. Besides, if anything goes wrong just pull over to the side of the road, oh! wait maybe that won't work.

tekochip
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Platinum
Re: Steer by wire??? I don't think so.
tekochip   12/23/2012 10:59:39 AM
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You know that was a popular challenge around our office and one ME, let's call her Christine, failed  the experiment with grand results.

William K.
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Platinum
Re: Steer by wire??? I don't think so.
William K.   12/21/2012 8:46:50 PM
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If you want to experience just how difficult anti-intuitive steering can be, try this experiment on a bicycle. After you get rolling along a straight clear path, grb the right-hand grip with your left hand and try to kep going straight. BUt be certain that your helmet is on correctly before doing this experiment.

Going to a non-intuitive steering method could be a real disaster.

bobjengr
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Platinum
Re: Mechanical Backup
bobjengr   12/15/2012 2:10:27 PM
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  I can certainly agree that maintenance and proper repair must be concerns relative to this technology.  The days of the shade-tree-mechanic are over forever with systems as sophisticated as this one.   I think back-up systems are an absolute must until enough reliability data and "road experience" are available.

ElectricShave
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Iron
Racing first
ElectricShave   12/6/2012 10:10:43 AM
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Tell you what: I'll buy if I see it win a race in a major event. Any of the big ones: Indycar, NASCAR, F1, F2000, GT, Paris-Dakar, whatever. If you show me a race team using drive by wire for a season and winning, then I'll buy it. 

If the technology is so great then show me. Any race team would love to shave weight, reduce parts and 'enhance' the driver's road feel. Also the drive-by-wire could deliver a lot of data to the race team computers. I can see how it would be a huge advantage.

So let's see it.

William K.
User Rank
Platinum
Re: Steer by wire??? I don't think so.
William K.   12/1/2012 7:54:35 PM
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I am not sure if there is a better way to steer a car than using the steering wheel. Consider that it never gets lost, and it is positioned so that it can be turned by either hand. Also, the motion is intuitive to almost everybody-turn the wheel right to turn right, about as easy to figure out as possible. If there were an electrical control for it, we might wind up like we are with seatbelt buckles, with a bunch of different kinds, and some of them are really TRASH, in that they are hard to connect and impossible to release wearing heavy gloves. Just think, they all started out just like the seatbelt buckles in airplanes. 

Steering could wind up being a function on that same stupid big red button that is used for start and stop on some inferior brands of cars.

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