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Non-mchanical Auto Steering

  1. Aug 9, 2010 #1
    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?

    Thank you

    ::: I'm not sure if this should be in Elec. or Mech. engineering forums, I apologize if it is incorrectly labeled.
     
  2. jcsd
  3. Aug 9, 2010 #2

    sophiecentaur

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    I'm sure that electronic control would take care of a lot of the problems but, when you get down to it, deflecting the wheels on one axle (usually the front) has just got to be a good way to produce a lateral force to turn the car with minimal scuffing of the tyres. Your suggestion is rather like steering a tank, which works fine at low speed and, I'm sure, has some advantages but I don't think you could complete a Formula One course quickly in a vehicle with 'tank' steering.
     
  4. Aug 9, 2010 #3

    mheslep

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    I suppose reliability is the concern, though that may be hype when compared to mechanical linkages. I don't know that a mechanical linkage is necessarily more reliable.

    From the Wiki:
    http://en.wikipedia.org/wiki/Drive_by_wire

    The Wiki is misleading regarding the DARPA contest. Most, if not all, of those vehicles used an electric servo motor attached to the stock mechanical steering linkage. Only one of the DARPA vehicles in the final had real drive by wire (Stanford, the winner), and that was limited to only the throttle.

    One of the major advantages of drive by wire steering is the elimination of the steering wheel. No more: body - steering wheel impacts in a crash, steering wheel adjustment for the driver, visual impairment of the instrument panel, etc.


    https://www.youtube.com/watch?v=-iiCrFp89hU
     

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    Last edited: Aug 10, 2010
  5. Aug 10, 2010 #4

    Ranger Mike

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    with enuff time and money anything is possible..don't forget that the " power steering" we now have will work even if the fluid is completely gone..safety concern..if you went total electric you need a back up system...Toyota just got severe head aches with electric throttle control
    ..now you want t o make steering electric??
    production costs and after market service is a factor..what alignment shop will have software to properly align the wheels if you ding a control arm on a curb? take it back to a dealership?
    we just cut out 50 percent of the dealerships in the country last year..
    keep it simple..
     
  6. Aug 10, 2010 #5

    mheslep

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    Like this?

    [PLAIN]http://www.rootsweb.ancestry.com/~gamadis2/images/horse_and_buggy.jpe [Broken]
     
    Last edited by a moderator: May 4, 2017
  7. Aug 10, 2010 #6
    Thank you all for your relies. I love the James May clip.
     
  8. Aug 10, 2010 #7

    mgb_phys

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    Last edited by a moderator: May 4, 2017
  9. Aug 10, 2010 #8

    mheslep

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    Emissions from passengers or the horse?
     
  10. Aug 10, 2010 #9

    mgb_phys

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    I don't think the horse's tailpipe emissions would pass 'aircare'
     
  11. Aug 11, 2010 #10

    Ranger Mike

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    close to perfection..now i can get home on auto pilot when i enjoy too many adult beverages at local watering hole...head for the barn, Ned..giddiapp
     
  12. Aug 11, 2010 #11

    mgb_phys

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  13. Aug 11, 2010 #12

    Ranger Mike

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    government will get you one way or another!!
     
  14. Aug 12, 2010 #13
    Not even remotely a chance that i'd be driving a car without a mechanical linkage, it's not just the point of the electric connection failing (as you can have multiple redundancies), what if your altenator fails and you run out of battery. At least you can still steer with a mechanical linkage.

    Also there is every chance that people will kill themselves at any sort of speed by not having any feel for the steering what so ever. You may not think it, but you'd be so surprised at just how much information you recieve subconsiously through the little vibrations and weighting of the steering wheel. The tyre lets you know when it's about to break free and lose it's grip, you can't have that with no physical connection between the steering wheel and road wheels.


    EDIT: It's cartainly possible though. If you were so inclined you could drive a car with a playstation controller. The actual physics of it are pretty simple.
     
  15. Aug 12, 2010 #14

    Janus

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    Several years ago I read an article about the future car design. One of the concepts brought up was active suspension. The suspension system could detect variations in the road surface and actively move the wheels to compensate. The idea was that you could "dial in" your ride.

    During test drives, when the system was put in full active mode as to give the smoothest possible ride, the drivers complained that they lost a feel for the road, which they found disconcerting.
     
  16. Aug 12, 2010 #15

    mheslep

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    Oh no! Someone tell this guy to eject!

    f16_4.jpg
    http://en.wikipedia.org/wiki/General_Dynamics_F-16_Fighting_Falcon#Flight_controls

    Seriously, we're already past the point of direct mechanical control for many car drivers. If the power steering fails then many females or the frail are unable to control the vehicle in all conditions.

    I agree with you on the importance of steering feedback, but some of that comes back to the driver through the chassis outside of the steering column. That is, even a passenger receives some feel for the road. Also, artificial feedback can flow to electric steering controls, just as it is now in aircraft stalls. Not that these points mean the problem is solved, but seems to indicate is solvable.

    Some current mech steering http://www.cbsnews.com/stories/2010/07/29/business/main6724183.shtml":
     
    Last edited by a moderator: Apr 25, 2017
  17. Aug 12, 2010 #16

    mgb_phys

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    Probably because they tested it with enthusiasts or track drivers - not suburban minivan drivers.
    By the same standard nobody would have introduced automatic transmissions.
     
  18. Aug 12, 2010 #17
    Very droll, point is if the **** hits the fan he CAN eject.

    You can build massive factors of safety into the mehanical components, just like you can can build backups and redundancies into the electrical system. Either way being a car nut and a mechanical engineer, I like large lumps of metal and not electrickary.

    EDIT: I'd also like to comment on power steering. I find that tends to deaden the feedback,. Especially in Puntos with the girly steering button on, the wheel just feels dead (im fairly sure you aren't suposed to drive above 15mph with it on, as it gives lolwobble moments). Give me no power steering on a quick rack any day, just dont ask me to parallel park!

    Chassis = rear wheels, steering wheel = front wheels. That's how I can tell what's doing what. I can gaurantee you in a front wheel drive car having a wheel that is like driving in the arcades will be scary as hell when you push on.

    There's also no way to replicate the direct transimssion of what the wheel is doing. If you are driving on low profile tyres, that will tend to 'snap' rather than give up their grip gradually then no atrificial feedback will let you know that.

    They have a system on the playstation, logitech G25 iirc. It's the closest thing to real life driving with GT5, the steering wheel weights up as you turn it, it also has pedal feel. As close as it is, it's just not the same as wheel - metal link - tyre - road.
     
    Last edited: Aug 12, 2010
  19. Aug 12, 2010 #18

    mheslep

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    No, not like electrical systems. In mechanical systems you generally get cascading mass and damping multipliers when you add either strength or redundancy safety factors, which in turn increases cost and impacts the performance of the overall system. For example, and grossly oversimplifying: stronger (or redundant) mechanical tie rods add mass to the steering assembly which requires stronger mechanical tie rods which ....

    Fair enough
     
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