JBee

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well, presumably the TeslaVision will prevent (e.g.) the CT back end grazing a car in the lane to your right when you're making a left turn...!

Rear steering makes a lot of sense for a vehicle with regular software updates. It hasn't really been done until now because it's surprisingly hard to control (getting it right for everyone, etc. ). I foresee some complaints no matter how well done it is lol...

As far as mechanical engineering goes, it's really not hard since this technology has been figured out for a long time. But CONTROLLING it is where it'll bite haha.

For example:
sure, tighter turns are great! But the rear tires angling outwards adds new collision possibilities. Since the turning radius can now start at the rear of the vehicle, rather than only pivoting around the rear axle, we're going to see a lot of folks "side driving" into things haha. It'll be important to understand that when you aim to turn left, your rear tires will be aiming RIGHT.
Good control and software can certainly fix this (and other weird cases) and make it amazing! It'll be interesting to see how Tesla implements all this.
I'm stoked!
Cheers!
The rear track will follow the front track and so the rear of the CT will not veer right when turning left.

The rear wheel turning angle will only be a fraction of the front wheel turning angle, because the rear wheel fender is not big enough to allow more angle without making the bed width smaller. I expect it to be around 10-15 degrees of turning on the rear.

No need for FSD to intervene on 4WS. There are many cars with 4WS, and most do it mechanically without any software, and they all work fine. I don't think there is a need for software updates, actually I would consider updating the steering behavior via software a risk as people will not expect the change. The only place I can think where software (and updates) might play a roll is in fringe cases or emergency situations, where it assists ABS/ESP etc to maintain control of the vehicle. Even there, it would be in Teslas best interest to have that onboard prior to production rather than an update late on.

This is not new tech there's a bunch of BMW, Merc and Porches etc that have it. Even GM.

Here's a video I found on on another thread here that demonstrates it well:

Sponsored

 

rr6013

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Ludicrous begat Plaid.

14000# towing begat RWS.

We now know what Plaid begat. Any clues what RWS enables NeXT?
 


WFrazier

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Could the CT do a "TANK TURN" if the front wheels turn all the way LEFT while the rear wheels turn all the way RIGHT. Perhaps a software selection will allow that maneuver.
I think the reason Elon added the rear steering is so it could compete heads up with the Hummer Crab Walk and Rivian Tank Turn.
a sketch of what i think you were saying
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this would probably squeal the tires a lot, unless you are in the dirt :)


Or if all wheels could turn independently and drive different directions,
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/----\
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do a swivel turn. Though I don't believe that this will happen.
 

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a sketch of what i think you were saying
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\----\
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/----/
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this would probably squeal the tires a lot, unless you are in the dirt :)


Or if all wheels could turn independently and drive different directions,
--
/----\
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| |
| |
\----/
--

do a swivel turn. Though I don't believe that this will happen.
At this point I wouldn’t bet against Elon deciding to fully trick out the CT.

Swivel turn might just be part of the plan. RWS hits the 1 noticeable extra feature of the Hummer. Swivel turn would do the same to Rivian.
 

SteveBaker

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I think there is some confusion here. All you get with rear-wheel steering is the ability to turn the rear wheels in the same direction as the front (the "crab walk") - or in the opposite direction, which gets you a tighter turning circle - but not much else.

TANK TURN: A "Tank Turn" doesn't even require rear-wheel steering (or any steering at all for that matter!). What it does is to put the wheels on the left side of the truck into reverse while the wheels on the right side are moving forwards (or vice-versa). Rivian can do that easily because they have a "hub motor" on every wheel...so each wheel could (in principle) be driven at a different speed and direction. But even the tri-motor CyberTruck doesn't have that. So absolutely, 100% certain - the CyberTruck WILL NOT HAVE "tank-turn" until/unless they make a quad-motor version.

It's really not a great idea anyway because unless you're on very soft ground, you're putting huge sideways forces onto the tires - which they simply aren't designed to take.

CRAB-WALK: This is good for changing lanes - you can change lanes more rapidly and with less lateral-forces, so it makes the car more comfortable to drive at high speeds. The tighter turning circle is most useful for slow speed maneuvering - so in the handful of production cars that have it - they make it speed sensitive - so it automatically crab-steers at high speeds and tightens the turning circle at low speeds. Sometimes there is a control that lets you crab-walk at slow speeds - but I don't think any production cars ever implemented that. When crab-walk is done at high speeds, existing cars turn the rear wheels by a smaller amount than the front wheels, so you still have some directional control - which you'll need if you're taking a turn at high speed. So without more software sophistication, you're not going to be literally driving the car diagonally anyway.
 

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At this point I wouldn’t bet against Elon deciding to fully trick out the CT.

Swivel turn might just be part of the plan. RWS hits the 1 noticeable extra feature of the Hummer. Swivel turn would do the same to Rivian.
I don't think Rivian turn all four wheels inwards like in your diagram. Adding true four-wheel steering with independent direction on each wheel would be crazy-complicated. I think it does exactly what a "skid steer" Bobcat does - keep all the wheels parallel - but put the wheels on one side of the vehicle into reverse while those on the other side are going forwards. Tanks and skid-steer vehicles like a Bobcat don't have wheels that turn at all.
 


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I don't think Rivian turn all four wheels inwards like in your diagram. Adding true four-wheel steering with independent direction on each wheel would be crazy-complicated. I think it does exactly what a "skid steer" Bobcat does - keep all the wheels parallel - but put the wheels on one side of the vehicle into reverse while those on the other side are going forwards. Tanks and skid-steer vehicles like a Bobcat don't have wheels that turn at all.
I'm not the one who came up with the 4-wheel independent steering idea. I'm just saying that with 4-wheel independent steering you could actually do what Rivian is doing but do it better.

You are correct that Rivian is doing a tank turn by essentially acting as a skid steer. And in order to do this kind of turn without wearing down your tires significantly, you would need to do this turn on soft surfaces only. What others have posited though is that Tesla might do 4-wheel independent steering. This could allow the vehicle to do a tank turn without wearing the tires down because there would be no scraping involved. Instead with the tires pointed in all 4 directions, you could literally spin the car on a central point just using normal rolling of the wheels. Given what others have said about this possibility, my point is simply that I wouldn't bet against Tesla doing something like that.

Is it feasible? Clearly, some have the idea that it might be possible. I would wonder about the needed angles of the wheels. It might be that the turn radius is too tight for normal steering. Other people are discounting it because the tires would scrape on the inside of the wheel wells. I'm not sure this is a true limitation though because if there is truly 20" of travel in the suspension, the CT could self-raise all the way up before the turn so that the tires have no possibility of hitting the wheel wells. Keep in mind that this kind of turn would almost certainly have to be started from a fully stopped position as trying to get the wheels into the correct position would really mess with any directional travel that the vehicle might otherwise be doing at the time.

As for your point:

Adding true four-wheel steering with independent direction on each wheel would be crazy-complicated.
I don't see that this would be so crazy complicated. More complicated than having 2 wheels linked and turning in the same direction all the time? Sure. But not crazy complicated. Instead of having a single line between opposite wheels that is pushed left or right in order to steer, there would need to be independent steer rods. So essentially just cut the linked steer rod in half, and use 2 actuators (1 independent one for each wheel). Of course, this is oversimplifying. When you get rid of the linked steering rods, you then have to have much more precise control over the steering position so that you can reliably deal with alignments. But is that crazy difficult? I'm willing to bet that it could be tackled by Tesla in a cost-effective and reliable way.

Now having said all that, do I believe this kind of feature will be on the CT? I have no idea. Personally, I don't NEEEEEED it. But if they were to have this feature incorporated, you can bet your bottom dollar that it would be the total talk of the town. It would totally out-do anything Rivian is doing. And this goes to my point. I wouldn't put it past Elon to add this kind of feature if only because the marketing impacts would be enormous. BUUUUUUT, only if it is cost-effective, reliable, and fits with his first principles. Given these criteria though, I wouldn't put it past Tesla to have exactly this feature.

But hey, I'm just an interested reservation holder. Either way, I'll be taking possession when my turn comes up. In the mean time, the speculations are just fun fodder to pass the time.
 

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Tesla is going to have to design some super amazing rear axle / suspension system that can handle towing 14k AND now has rear wheel steering.

I have to keep telling myself the CT is a 1500 series truck. Maybe a 2500 sorta kinda wanna be.

I'm having mixed feelings about the rear wheel steering. RWS is definitely a step in in the luxury pickup direction, and a step away from a heavy duty truck you would want to tow with.

There are many ways to accomplish RWS.

Porsche has RWS on the 911. It uses variable length tie rods. Simple actually.

Tesla Cybertruck Rear Wheel Steering 1625618072088
 

Mini2nut

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I am confident that RWS was part of the Cybertruck design from the very beginning. I am looking forward to more CT details via EM Tweets in the next few months. Nobody knows how to build vehicle hype and anticipation better than EM.
 

firsttruck

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Tesla is going to have to design some super amazing rear axle / suspension system that can handle towing 14k AND now has rear wheel steering.

I have to keep telling myself the CT is a 1500 series truck. Maybe a 2500 sorta kinda wanna be.

I'm having mixed feelings about the rear wheel steering.

RWS is definitely a step in in the luxury pickup direction, and a step away from a heavy duty truck you would want to tow with

Actually if implemented correctly it can be the opposite.

Truck with rear wheel steering might have greater payload & towing abilities by thousands of pounds than non rear steer models.

Examples:

2004 1/2 ton GMC Sierra/Chevrolet Silverado 1500 and 2500 (non HD)
2004 3/4 ton GMC Yukon XL / Chevrolet Suburban XL


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General Motors Quadrasteer Technology
https://gmauthority.com/blog/gm/gen...chassis-suspension-technology/gm-quadrasteer/

.....
Compared to vehicles without Quadrasteer, vehicles with the feature have a smaller turning radius. This can be very handy for big vehicles such as pickup trucks and SUVs when parking in small spaces. In addition, a smaller turning circle is particularly useful for those who tow boats, fifth wheels, or other large equipment, as it enables easier maneuverability when towing and parking.

The Quadrasteer system adds about 285 pounds of additional weight to the truck but gives back this amount and more in additional towing and hauling capabilities over the C3.
The rear axle’s weight rating increases by 250 pounds to 4,000 pounds and maximum GCWR (gross combined weight rating) climbs from 14,000 to 16,000 pounds.
Towing capacity has increased from 8,700 pounds to 10,000 pounds. The wider rear axle also provides more stability when towing.

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Sponsored

 
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