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Captain Hybrid

Steer-By-Wire to Reach Production Vehicles

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jmiller
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Platinum
Re: Mechanical Backup
jmiller   11/30/2012 10:43:07 PM
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I agree there needs to be someway to get the wheels to turn if things go wrong.  Locking straight until the broken wire is fixed is just unacceptable on something like a car.

William K.
User Rank
Platinum
Steer by wire? A lot cheaper to make.
William K.   11/30/2012 8:11:03 PM
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Steer by wire allows getting rid of the engine driven hydraulic pump, but so does electrically assisted power steering. Totally removing the steering gear as it now exists gets rid of a bunch of fairly precision parts and allows the use of a much cheaper position servo system, since it does not need to be accurate because drivers go by what the car does, not where the wheel is. Completely blind drivers are a different case, though.

Drive by wire would also get rid of the strong supports for the steering wheel, since the driver is only sending a position command, probably to a computer. Would you want a computer deciding that a sharp swerve to avoid hitting someone was an unsafe move, and not make it?, or refuse to swerve around a broken bottle in the roadway? And WE KNOW that the programmers at Nissan are all "much smarter than we are". So drive by wire is still fine for planes and trains, although I understand that current Diesel engines do have a totally manual means of stopping and shutting down available.

Charles Murray
User Rank
Blogger
Re: Steer by wire??? I don't think so.
Charles Murray   11/30/2012 6:48:59 PM
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I could be wrong, but I believe one of the big advantages of steer-by-wire right now lies in the manufacturing differences between left-hand drive and right-hand drive. Right now, that's a big change, going from left to right to accommodate sale in other countries. If you take away the mechanicals, though, the manufacturing change is no big deal. For that matter, you could put the steering wheel in the back seat, or you could use a joystick to drive the car, and that wouldn't be a very big deal, either.

William K.
User Rank
Platinum
Steer by wire??? I don't think so.
William K.   11/30/2012 2:41:10 PM
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It seems that all of those commenting don't like the concept of steer by wire for a number of different reasons. And all of the reasons presented do appear to be quite valid.

Of course the reason that Nissan wants to sell it is because it reduces the cost to build the vehicle, not because of any improvement that it offers. But that would never sell, so they need to make up some tale about how wonderful it would be.

I really don't like it at all when people or companies lie to me.

 

Chuck_IAG
User Rank
Platinum
if all else fails...
Chuck_IAG   11/30/2012 2:37:29 PM
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If you had a general failure, the mechanical steering linkage is expected to kick in.  But if you had a general failure, what are the chances that the one thing to work would happen to be the clutch to re-engage the mechanical steering?  If the electric clutch mechanism is never used, then it'll very possibly be corroded or stuck or whatever.  I never used the power window switches for the rear windows in my old BMW for years at a time.  When I finally did, corrosion had coated the contacts and they didnt work.  Somehow I would not have a lot of confidence in the backup systems here.  What would be the recommendation... hammer on the steering wheel to free it as the car veers off the road?  Or just duck and pray?

jfs1970
User Rank
Gold
Re: Steer by wire??? I don't think so.
jfs1970   11/30/2012 11:22:27 AM
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Plus, Hydraulic power steering gives you some warning when it is going to fail: grinding noises in the pump, squeeling belts, increased steering effort.  What warning does a steer by wire give?

Rob Spiegel
User Rank
Blogger
Re: Mechanical Backup
Rob Spiegel   11/30/2012 9:53:58 AM
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That is a scary thought, Tim. I just can't see giving up the mechanical tie to steering. You would need -- at least -- a separate battery backup. 

tekochip
User Rank
Platinum
Re: Steer by wire??? I don't think so.
tekochip   11/30/2012 9:16:00 AM
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Don't compare this idea with aircraft fly-by-wire systems because there is no comparison.

 
Aircraft have air worthiness inspections every year and every 100 hours as well as being required to follow all recommended maintenance from the manufacturer and air worthiness directives from the FAA.  Now, contrast that with how many times you've seen the Check Engine light glowing on a car that just whizzed past you 20MPH above the speed limit with a hood that hasn't been opened in the last two years.
 
The average motorist can't be bothered with oil changing let alone maintenance and inspection to a drive by wire system.


rmclemore
User Rank
Iron
Re: Mechanical Backup
rmclemore   11/30/2012 8:00:37 AM
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I wouldn't want it. I remember when several other vehicles had problems with the accelerator acting with a mind of it's own. Now we will have to worry about the car going left when you want to go right. Let alone maintenace, something else to break and have the dealer take your arm to pay for it.

 

Tim
User Rank
Platinum
Re: Mechanical Backup
Tim   11/30/2012 2:47:08 AM
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I would hope that the automakers would take into account when the vehicle might run out of fuel which unfortunately occurs quite a lot.  At least with a vehicle with a current steering linkage, you can coast to the shoulder with some steering mobility.  It would be terrible if your wheels locked in their current orientation and you could not nudge your vehicle out of traffic.

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