lorenfb
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Re: Official Tesla Model Y Thread

Wed Jul 29, 2020 3:32 pm

goldbrick wrote:
Wed Jul 29, 2020 1:10 pm
Drive by wire means 'accelerator pedal to speed control' to me, not steering or braking or anything else. I'd be surprised if any production cars don't have a direct mechanical link between the steering wheel and the tie rod ends. I'd also be surprised if there were any that didn't have a direct hydraulic link between the brake pedal and the calipers.
Each has his own basic meaning. The key point is what Tesla does, i.e. typically minimizing mechanical systems and maximizing firmware control.
Last edited by lorenfb on Wed Jul 29, 2020 3:38 pm, edited 1 time in total.
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cwerdna
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Re: Official Tesla Model Y Thread

Wed Jul 29, 2020 3:38 pm

WetEV wrote:
Wed Jul 29, 2020 9:30 am
lorenfb wrote:
Wed Jul 29, 2020 7:50 am
LeftieBiker wrote:
Tue Jul 28, 2020 8:32 pm
I'll bet it uses the same steering rack as the Model 3.
Remember that most all vehicles presently are "drive-by-wire", which means that there's no mechanical connection from the steering
wheel to the steering rack. The system uses an ECU to drive a motor with feedback to control the ratio. This can provide for various
steering ratios, e.g. a sport mode.
https://en.wikipedia.org/wiki/Drive_by_ ... er_by_wire
The first production vehicle to implement this was the Infiniti Q50., but after negative comments they retrofitted the traditional hydraulic steering.
Is there any production car today that is steer by wire?
I knew about the Q50 going steer-by-wire long ago but didn't know that they went back to conventional... but it seems like they offered it (again) w/model year '18?

https://www.foxnews.com/auto/infinitis- ... -sport-400
https://www.wardsauto.com/test-drives/1 ... g-has-come
https://www.caranddriver.com/reviews/a1 ... ve-review/

I believe steer-by-wire is still the exception and not the norm in currently sold vehicles.

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GRA
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Re: Official Tesla Model Y Thread

Wed Jul 29, 2020 5:14 pm

dgpcolorado wrote:
Wed Jul 29, 2020 9:09 am
GRA wrote:
Tue Jul 28, 2020 7:19 pm


BTW, that's the second Mod Y review I've read that says the steering's too quick. 2 turns lock-to-lock for a top-heavy CUV makes no sense: 2.5 - 3 would seem to be more reasonable.
CUVs may be top-heavy in general but with the battery under the floor that isn't the case for most EVs, especially Teslas. The higher seating position may make drivers used to regular top-heavy CUVs feel uncomfortable but once they get used to the very low CG they may become accustomed to the flat EV handling on curves.

I was speaking in relative, not absolute terms when I mentioned top-heavy. The Model Y is definitely top-heavy compared to the 3, and C&D and others who've driven both mention the difference. The typical driver may never notice it, but people who tend to push their vehicles closer to the handling limits, which applies to C&D editors as well as most of their readers, will.
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goldbrick
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Re: Official Tesla Model Y Thread

Wed Jul 29, 2020 6:44 pm

lorenfb wrote:
Wed Jul 29, 2020 3:32 pm
Each has his own basic meaning. The key point is what Tesla does, i.e. typically minimizing mechanical systems and maximizing firmware control.
As a professional firmware developer and amateur car mechanic I still prefer to have a mechanical link. Until and unless car manufacturers start using avionic level firmware development techniques I'll stick with the KISS principle.

GRA
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Re: Official Tesla Model Y Thread

Wed Jul 29, 2020 9:25 pm

^^^AFAIA, full steer by wire with no mechanical linkage remains illegal in the U.S. and most if not all other countries for passenger cars. As for KISS I'm with you, for this and driver assistance systems like "Autopilot". Give me a true SAE L4 or L5 system, or don't bother.
Guy [I have lots of experience designing/selling off-grid AE systems, some using EVs but don't own one. Local trips are by foot, bike and/or rapid transit].

The 'best' is the enemy of 'good enough'. Copper shot, not Silver bullets.

lorenfb
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Re: Official Tesla Model Y Thread

Thu Jul 30, 2020 9:14 am

GRA wrote:
Wed Jul 29, 2020 9:25 pm
^^^AFAIA, full steer by wire with no mechanical linkage remains illegal in the U.S.
Link please.
#1 Leaf SL MY 9/13: 76K miles, 47 Ahrs, 5.0 miles/kWh (average), Hx=70, SOH=73, L2 - 100% > 1000, temp < 95F, (DOD) > 20 Ahrs
#2 Leaf SL MY 12/18: 10.3K miles, SOH 109Ahrs/115Ahrs, 5.2 miles/kWh (average), DOD > 20%, temp < 105F

GRA
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Re: Official Tesla Model Y Thread

Thu Jul 30, 2020 4:50 pm

Mainly the wiki, which says:
This kind of system will provide steering control to a car with fewer mechanical components/linkages between the steering wheel and the wheels.[4] The control of the wheels' direction will be established through electric motor(s) which are actuated by electronic control units monitoring the steering wheel inputs from the driver. Such a system is illegal in most jurisdictions for passenger or commercial vehicles.

https://en.m.wikipedia.org/wiki/Drive_b ... er_by_wire


There are also various discussions on tmc and elsewhere saying that laws would have to be changed to allow it. I haven't been able to find a reg, but haven't looked hard.

It's tenuous, but given the public's reluctance to trust their lives to automation, not to mention concerns about hacking, it seems likely there's still such a prohibition here.
Guy [I have lots of experience designing/selling off-grid AE systems, some using EVs but don't own one. Local trips are by foot, bike and/or rapid transit].

The 'best' is the enemy of 'good enough'. Copper shot, not Silver bullets.

LeftieBiker
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Re: Official Tesla Model Y Thread

Thu Jul 30, 2020 8:17 pm

It's tenuous, but given the public's reluctance to trust their lives to automation, not to mention concerns about hacking, it seems likely there's still such a prohibition here.
Cars with electric-assisted power steering units that are electronically linked to a CAN type setup can still be hacked, IIRC - it's been demonstrated. Think "Pro Pilot."
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lorenfb
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Re: Official Tesla Model Y Thread

Thu Jul 30, 2020 8:27 pm

GRA wrote:
Thu Jul 30, 2020 4:50 pm
Mainly the wiki, which says:
This kind of system will provide steering control to a car with fewer mechanical components/linkages between the steering wheel and the wheels.[4] The control of the wheels' direction will be established through electric motor(s) which are actuated by electronic control units monitoring the steering wheel inputs from the driver. Such a system is illegal in most jurisdictions for passenger or commercial vehicles.

https://en.m.wikipedia.org/wiki/Drive_b ... er_by_wire


There are also various discussions on tmc and elsewhere saying that laws would have to be changed to allow it. I haven't been able to find a reg, but haven't looked hard.

It's tenuous, but given the public's reluctance to trust their lives to automation, not to mention concerns about hacking, it seems likely there's still such a prohibition here.
Most should be aware that a similar system on ICEVs, i.e. full electronic control of the engine's throttle body (the accelerator pedal has no mechanical linkage), has been utilized for over 15 years for most all ICEVs. Hacking becomes extremely difficult when a subsystem ECU, e.g. electronic throttle where the throttle pedal potentiometers are hardwired to the throttle ECU and it operates under its own firmware.
#1 Leaf SL MY 9/13: 76K miles, 47 Ahrs, 5.0 miles/kWh (average), Hx=70, SOH=73, L2 - 100% > 1000, temp < 95F, (DOD) > 20 Ahrs
#2 Leaf SL MY 12/18: 10.3K miles, SOH 109Ahrs/115Ahrs, 5.2 miles/kWh (average), DOD > 20%, temp < 105F

GRA
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Re: Official Tesla Model Y Thread

Thu Jul 30, 2020 9:20 pm

lorenfb wrote:
Thu Jul 30, 2020 8:27 pm
GRA wrote:
Thu Jul 30, 2020 4:50 pm
Mainly the wiki, which says:
This kind of system will provide steering control to a car with fewer mechanical components/linkages between the steering wheel and the wheels.[4] The control of the wheels' direction will be established through electric motor(s) which are actuated by electronic control units monitoring the steering wheel inputs from the driver. Such a system is illegal in most jurisdictions for passenger or commercial vehicles.

https://en.m.wikipedia.org/wiki/Drive_b ... er_by_wire


There are also various discussions on tmc and elsewhere saying that laws would have to be changed to allow it. I haven't been able to find a reg, but haven't looked hard.

It's tenuous, but given the public's reluctance to trust their lives to automation, not to mention concerns about hacking, it seems likely there's still such a prohibition here.
Most should be aware that a similar system on ICEVs, i.e. full electronic control of the engine's throttle body (the accelerator pedal has no mechanical linkage), has been utilized for over 15 years for most all ICEVs. Hacking becomes extremely difficult when a subsystem ECU, e.g. electronic throttle where the throttle pedal potentiometers are hardwired to the throttle ECU and it operates under its own firmware.

Quite so, but steer by wire seems to be much more restricted; you can always turn the power off to stop runaway accel. Re: steer by wire, the wiki goes on to say:
The first production vehicle to implement this was the Infiniti Q50.,[5] but after negative comments they retrofitted the traditional hydraulic steering.[6] Its implementation in road vehicles is limited by concerns over reliability although it has been demonstrated in several concept vehicles such as ThyssenKrupp Presta Steering's Mercedes-Benz Unimog, General Motors' Hy-wire and Sequel, Saabs Prometheus and the Mazda Ryuga. A rear wheel SbW system by Delphi called Quadrasteer is used on some pickup trucks but has had limited commercial success.

The Swedish startup Uniti will release the Uniti all electric car in 2019 with an in-house designed steer-by-wire system and will entirely replace the steering wheel.[7] The concept was showcased in VR at the 2016 CeBit edition.[8]

Also found this:
In currently used electric steering systems, the safe state will be the intended loss of assist (LOA) for preventing unintended self-steer or inappropriate vehicle lateral control, and the related studies give guidelines for fault-tolerant systems. Regulations regarding steering systems strictly demand the human driver can steer in the LOA condition. e.g., ECE R79. However, in a steer by wire system, there can be no mechanical coupling between the steering wheel and the steering mechanism, the motor-off can be the safe state no longer.

https://www.sae.org/publications/techni ... 0-01-0646/
Guy [I have lots of experience designing/selling off-grid AE systems, some using EVs but don't own one. Local trips are by foot, bike and/or rapid transit].

The 'best' is the enemy of 'good enough'. Copper shot, not Silver bullets.

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