Cybertruck Shows Off Crab Walk at GFTX!

[fritter63]

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

Yes, I can see a need for it.

I always give up on those type of spots because I never trust the other drivers (front and back) to get out without hitting me....

Sponsored

 

[bruce91748]

Looks like a bad frame straightening job was done on a previously crash tested CT.

 

[Deleted member 17810]

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

I knew dog tailing seemed wrong.

 

[Crissa]

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.

https://www.google.com/search?rls=en&q=hand+over+hand+steering+versus+airbag

Hand over Hand is a deprecated technique. With modern vehicles, especially American ones, your hands in an intermediate position will crush them against your face when the airbag deploys.

-Crissa

 

[JBee]

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.

The problem I see with that is that the ackerman linkage is holding the wheel alignment also whilst turning. I think this is harder to achieve mechanically, if you don't have the two wheels of the same axle interconnected mechanically. The steering force will be considerably more per wheel, seeing that most vehicles have a slight toe out to achieve self centering steering. You can't do this with two separate left and right electric racks, as each would have to be actuated to keep alignment with each other. Having four of those will likely make it even worse and more sensitive.

Accordingly, I doubt the tank turn it achieves will ever be worth all the effort, and doubling up the actuation and the redundancies just to do that one function.

That's interesting that Tesla is sourcing steering components from Land Rover.

 

[JBee]

https://www.google.com/search?rls=en&q=hand+over+hand+steering+versus+airbag

Hand over Hand is a deprecated technique. With modern vehicles, especially American ones, your hands in an intermediate position will crush them against your face when the airbag deploys.

-Crissa

I'm not sure what you are talking about. Hand over hand turning wasn't mentioned in his post?

We are talking about if the CT is SbW?

 

[Warhawk123162]

Out in the real truck as a tool world, AKA a job site, this would be useful putting that piece of equipment right where it needs to be.

 

[Tiberius]

for the folks late to the party and what four wheel steering is and if its so called steer by wire.
Rear wheel steering is almost always steer by wire, regardless of what the front wheels do.
Additionally the so called crab walking has been a part of almost every 4WS systems since they started.
Useful explainer in an old 7 year old video from Brian Cooley and CNET

 

[Dazureus]

The problem I see with that is that the ackerman linkage is holding the wheel alignment also whilst turning. I think this is harder to achieve mechanically, if you don't have the two wheels of the same axle interconnected mechanically. The steering force will be considerably more per wheel, seeing that most vehicles have a slight toe out to achieve self centering steering. You can't do this with two separate left and right electric racks, as each would have to be actuated to keep alignment with each other. Having four of those will likely make it even worse and more sensitive.

Accordingly, I doubt the tank turn it achieves will ever be worth all the effort, and doubling up the actuation and the redundancies just to do that one function.

That's interesting that Tesla is sourcing steering components from Land Rover.

I'm much less experienced on the mechanical engineering side of steering systems since my domain is purely software and the accompanying knowledge required to fulfill that role. In my mind, far in the future when we have hub motors and full independent 4-wheel SbW, I don't see why we couldn't have more power steering motors and robust associated mounting points that could be individually calibrated for desired toe degrees. Wheel alignments would be performed via individual steering motor angle sensors. Again, I can't speak to the mechanical disadvantages decoupling the wheels would cause, but in my optimistic mind, I can't see why those disadvantages couldn't be overcome with engineering.

 

[SparkChaser]

Mechanical connections also act as a backup if the drivers can handle the torque required. Having some way to isolate them when both are functioning allows individual wheel steering. Having a failure allow the one surviving driver turn both wheels could allow you to limp home.

 

[AustroTom]

Useless crap at additional cost

 

[Barb]

I thought I saw a video a number of years ago about how it would be used. I think one of the examples was to get into a tight parallel parking situation... This example didn't look like it would be capable of that. I really didn't see much going on, but then again, I'm really not a car fanatic!

Sponsored