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Is there a mechanical link to driveshaft?

Discussion in 'Autonomous Vehicles' started by apacheguy, Mar 22, 2017.

  1. apacheguy

    apacheguy S Sig #255

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    Do AP2 cars have a mechanical link to the driveshaft from the steering column or is it drive by wire?

    Basically wondering if someone exploited a Tesla remotely could they cause the car to veer off the road even if the driver took over control?
     
  2. Tam

    Tam Active Member

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    Autopilot means an operator is in control and responsible at all time even when the automation is active.

    It also means that whenever the automation detects a manual input, it would disengage itself and yield to human skills and judgement.

    Thus, a hacker has to override that principle so that the automation would disregard all manual inputs.
     
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  3. stopcrazypp

    stopcrazypp Well-Known Member

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    I'm pretty sure if Tesla used steer by wire they would announce it. I would expect it uses electric power steering like all Teslas so far.

    As far as I know the only steer by wire system is the DAS for the Infiniti Q50 and that one also has a mechanical backup.
     
  4. Tam

    Tam Active Member

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    An example of remote take over for a 2014 Jeep:


     
  5. Tam

    Tam Active Member

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    I am not sure a "mechanical link" would help with the example of 2014 Jeep take over above.

    In Tesla, if the power is down, you can still control the car without power assist in steering and braking.

    So I assume there is still some mechanical link system for steering and brake.

    But mechanical brake didn't help to brake the Jeep in the end and the remote took over the brake system and ignored the manual brake pedal and let the car ran into a ditch.
     
  6. Drewflux

    Drewflux Member

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    @apacheguy yes its a mechanical link from the column to the steering rack. I'm not aware of any vehicle on the market with steer by wire yet.
    Hydraulic servo remote steering has been a thing in the past (no mechanical link)
     
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  7. scaesare

    scaesare Well-Known Member

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    Yes... a link to the steering rack, as has been mentioned (driveshaft is a different thing... the Model S doesn't even have one)

    Additionally, here's some INFO on the unit I believe they are using.
     
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  8. apacheguy

    apacheguy S Sig #255

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    Yes, I am familiar with Charlie and Chris's work. The Jeep must not have a mechanical brake system, though. There is no way to electronically override physical force being applied to the brakes.

    In a Tesla, the software can activate AEB, but it cannot override the drivers foot on the pedal.
     
  9. apacheguy

    apacheguy S Sig #255

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    Sure it does. How else does the drive unit transfer torque to the wheels? From Wikipedia:

    "A drive shaft, driveshaft, driving shaft, propeller shaft (prop shaft), or Cardan shaft is a mechanical component for transmitting torque and rotation, usually used to connect other components of a drive train that cannot be connected directly because of distance or the need to allow for relative movement between them."
     
  10. Saghost

    Saghost Active Member

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    I believe the S and X are both dual pinion electric steering systems, like a number of modern cars.

    What that means is you have a solid mechanical rack and pinion system on the driver's side, and then a second rack and pinion on the passenger side with an electric motor hooked up.

    No hacking can prevent the steering wheel from turning with the front wheels. Whether you have the strength to overcome the steering motor is a separate question that we'll hopefully never have to find out.
     
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  11. spottyq

    spottyq Member

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    Well, anyways the point is moot because even if the steering wheel has a direct mechanical link to the wheels (which I believe it does) and the "bad guys" decide to turn the wheels on the highway by surprise, I'm sure I wouldn't be able to override it by force before something bad happens. (When driving 120km/h / 75mph on your average freeway, while you have a few car length of breathing space in front and back, you barely have a meter left and right…)

    The only thing protecting you against that is Tesla's security. And the fact that it wouldn't do anything positive for the "bad guys".
     
  12. scaesare

    scaesare Well-Known Member

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    Perhaps according to the strict dictionary definition, but not according to the generally accepted automotive definition. It has axle- or half-shafts for the drive units.

    And generally there's no driveshaft that a steering column would be connected to, as per the original question.
     
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  13. Skotty

    Skotty 2014 Model S P85

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    I think keeping a mechanical link is a good thing. Not so much as a backup against hacking, but just as a backup in case of electrical/computer system failure. My wife has experienced power steering failure in our P85 (had it repaired under warranty; service center indicated bad plug connection). Without the mechanical link, it could have been far more dangerous.
     
  14. Drewflux

    Drewflux Member

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    Unfortunately any connected vehicle is at potentially risk. If a hacker did get in. ( tesla make it very hard though)
    You could make the steering turn at any speed if you know how the system operates.
     
  15. Drewflux

    Drewflux Member

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    Yes it is a good back up, as the assistance from the electric motor is actually stronger than the average person. Someone recently posted about a failure where the power assistance was actually fighting his input. I.E could not be turned.

    Its something that shouldnt be able to happen with the built in double redundancies. In this type of fault the power assistance Should turn off, leaving manual steering only.
     
  16. apacheguy

    apacheguy S Sig #255

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    Oh, that's scary. They should have designed it so that the steering motor used for AP is at a mechanical disadvantage compared to driver input. That just makes sense. No idea why the motor should be stronger than a driver.
     

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