Cybertruck Shows Off Crab Walk at GFTX!

[WHIZZARD OF OZ]

4WS - helping park big trucks in tight spaces . . .

'Cyber Shoe Horn' helps!
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[JBee]

Good job that a Cybertruck can't walk then.

 

[Dazureus]

Well atleast this confirms, CT has steer by wire.

Look at lock to lock the drivers arm doesnt go full 360 at all

That caught my eye too, but I'm not sure it confirms steer by wire yet. It does confirm a high steering gear ratio. To confirm steer by wire, we would need to see the same hand wheel angle travel with low wheel deflection angle. Then we would know that the hand wheel isn't mechanically connected to the rest of the rack and it's only the EPS that's providing the steering torque.

A high steering ratio would be useful for a yoke-like hand wheel since hand over hand operations are a little more cumbersome when the hand wheel isn't at a predictable circumference throughout the end-to-end rotation. We've seen some other videos where the steering ratio looks high, but I have yet to see a video where the steering ratio looks low, so it's difficult to confirm SbW.

 

[Deleted member 17810]

You can retire now.

 

[Gilbertus]

This looks more like a malfunction to me

In fact now that I watch it again im sure its broken

my thoughts

 

[JBee]

That caught my eye too, but I'm not sure it confirms steer by wire yet. It does confirm a high steering gear ratio. To confirm steer by wire, we would need to see the same hand wheel angle travel with low wheel deflection angle. Then we would know that the hand wheel isn't mechanically connected to the rest of the rack and it's only the EPS that's providing the steering torque.

A high steering ratio would be useful for a yoke-like hand wheel since hand over hand operations are a little more cumbersome when the hand wheel isn't at a predictable circumference throughout the end-to-end rotation. We've seen some other videos where the steering ratio looks high, but I have yet to see a video where the steering ratio looks low, so it's difficult to confirm SbW.

Thanks for the clarification.

I'd like to add that it is difficult in general to observe SbW at all, if the vehicle has a mechanical variable rate steering, that would appear to operate similar to a SbW setup. Especially, if no proper comparison can be made between steering input and wheel output angle, for two or more different vehicle speeds.

In saying that though, given that the rear steering is likely to be SbW on the CT, the need for having a front SbW setup is probably not required, as the rear can actively adapt steering angle based on velocity, and as such add some active steering control to the front, along with stability for parallel steering for lane changes etc.

Because the rear steering is limited in angle, it's also very likely that the front steering will suffice to maintain control over the vehicle even if the rear steering is stuck on maximum steering angle through a fault, as appears to be the case in the video.

I think a hybrid of mechanical in the front (lower cost) and SbW (electric) in the rear is a good combination and compromise for a 4WS system in the CT.

 

[cvalue13]

Tesla employee 1: "i thought of a new 'test' for rear wheel steering"

Tesla employee 2: "tell me about it"

E1: "well, you make the rear wheels point full lock in a single direction - let's say full right - and leave it that way regardless if the truck front wheels are turning left or right, and then see what happens"

E2: *stares*....





... "you broke the rear steering again didn't you?

 

[C T Rick]

Construction sites where parking and material placement is at a premium.

Living in a city like Los Angeles where parking is a premium and fitting into a tight space requires skills.

Heck, give me perpendicular steering so I can get in and out with inches to spare.

Yes, I can see a need for it.

Rick

 

[Dumb Game]

That's more dog tailing

lol... My 1995 ZJ with bad wheel alignments Crab walk better than that. "Dog legging"

 

[Dazureus]

Thanks for the clarification.

I'd like to add that it is difficult in general to observe SbW at all, if the vehicle has a mechanical variable rate steering, that would appear to operate similar to a SbW setup. Especially, if no proper comparison can be made between steering input and wheel output angle, for two or more different vehicle speeds.

In saying that though, given that the rear steering is likely to be SbW on the CT, the need for having a front SbW setup is probably not required, as the rear can actively adapt steering angle based on velocity, and as such add some active steering control to the front, along with stability for parallel steering for lane changes etc.

Because the rear steering is limited in angle, it's also very likely that the front steering will suffice to maintain control over the vehicle even if the rear steering is stuck on maximum steering angle through a fault, as appears to be the case in the video.

I think a hybrid of mechanical in the front (lower cost) and SbW (electric) in the rear is a good combination and compromise for a 4WS system in the CT.

I agree with you. In the absence of any pictures showing the rack, I'm guessing it will use a high gear ratio pinion w/ traditional EPS for the front and SbW for the rear. Since the road wheels move at a steady deflection throughout the hand wheel rotation in the video, we're not looking at a simple mechanical variable gear ratio. I don't think Tesla would implement the more complicated planetary gear set (ala BMW Active Steering). I'm guessing the steering high ratio will allow drivability at various speeds with a variable torque assist curve dependent upon vehicle speeds and hand wheel torque input. I think the only way we'll know for certain is if we hear it directly from Tesla, or get spy shots of the steering rack. Tesla SbW patent shows dual EPS (dual pinion), which would be easily identifiable if we could get a picture of it.

 

[JBee]

I agree with you. In the absence of any pictures showing the rack, I'm guessing it will use a high gear ratio pinion w/ traditional EPS for the front and SbW for the rear. Since the road wheels move at a steady deflection throughout the hand wheel rotation in the video, we're not looking at a simple mechanical variable gear ratio. I don't think Tesla would implement the more complicated planetary gear set (ala BMW Active Steering). I'm guessing the steering high ratio will allow drivability at various speeds with a variable torque assist curve dependent upon vehicle speeds and hand wheel torque input. I think the only way we'll know for certain is if we hear it directly from Tesla, or get spy shots of the steering rack. Tesla SbW patent shows dual EPS (dual pinion), which would be easily identifiable if we could get a picture of it.

Hey while I've got you on the line, what do you think about this proposed "Diamond Steering" idea that pops up now and again on the forum? Personally, I think it will be essentially like having 4 separate SbW, really only to achieve a "better" but fairly impractical "tank turn" but then run into a bunch of alignment issues and wear.

 

[Gojuryu]

Looked more like the rear wheels were stuck at an angle giving the appearance that the alignment was totally out of spec. Could explain why having to turn the front wheels fully to the left and right to reset the digital steering.

 

[egandalf]

I believe that this is achieved via software coding for the rear wheel steering. Interesting to see, but not much use in the real world, IMHO.

I think we will find more useful opportunities than expected. I sort of agree, but then I also think of all the times I wish could just ease closer to the curb without Austin-Powers-ing my vehicle or nudge the vehicle a little bit in a parking space to get a better center line, reach a charging cable, or move farther from the bollard.

We can probably all agree that 4WS is a net good to get a tighter turn radius. We may be surprised by the utility of crab-walk, which, after all, is just another software mode for 4WS. For no extra cost, I'll definitely take it and find my own use.

 

[egandalf]

I can tell you that parking a big truck in a little parkinglot sucks. You'll appreciate 4WS every. single. day.

Can attest. Even with a mid-size truck like a Tacoma. It's wildly different from parking a sedan.

 

[Dazureus]

Hey while I've got you on the line, what do you think about this proposed "Diamond Steering" idea that pops up now and again on the forum? Personally, I think it will be essentially like having 4 separate SbW, really only to achieve a "better" but fairly impractical "tank turn" but then run into a bunch of alignment issues and wear.

Tesla's SbW patent only shows front steering and it shows a dual pinion EPS on a single rack. It shows a single rack bar and the dual EPS are for safety redundant purposes. It's not entirely clear if the primary EPS can handle all steering torque assist and the secondary is redundant standby, or if they're both assisting 50% steering torque, but the single rack bar prohibits each wheel from independent steering. I haven't seen clear pictures of the Cybertruck rear steering, but I'm guessing it's SbW with a single rack, similar to the patent. The images shared by greentheonly don't provide any direct images of either front or rear steering components and I'm not smart enough to be able to interpret the rear casting mounting points, but from an engineering prospective, I think it unlikely that Tesla would spend the extra cost to have disconnected steering units on the rear SbW.

Other than that, if a vehicle did one day implement 4 wheel independent steering and independent drive motors, then that Diamond steering would be possible. Wheel alignment could probably be recalibrated on the fly with wheel angle torque sensors vs hand wheel angle input or something.

As a side note: Digging deeper into who manufacturers Tesla steering racks, I came across a few Tesla Owners Club posts about DIY rack replacements on the older Model S. It appears at least those models used Land Rover steering racks, specifically from the Evoque. Range Rover Sport has a rear steering system but I can't find a good picture showing the implementation.

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