Steer By Wire - hope Cybertruck has it

[LDRHAWKE]

Steer by Wire is already on the market……Lexus has it. Great video below. Hope the CT has it.

All Tesla needs to do is improve on it to get progressive steering to make the yoke wheel work great. Tesla has applied for steer by wire patents. Don’t be surprised to see it.

youTube…”How Lexus Fixed Tesla’s Bad Idea”…Steer-By-Wire Yoke….
…Engineering Explained

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[DrShah]

Hoping it does … maybe it won’t come out on the early production models but hopefully eventually.

 

[Baldey]

FSD is steer by computer so SbW has little or no advantage.

What do you mean StB has no advantage in a computerized system? it has all of the same advantages, if not more:

Instead of adding an actuator to the steering column to facilitate FSD, you get rid of the steering column and turn the wheels directly by moving the rack for both FSD and driver input. Best part is no part? How doesn't it save on weight, cost, and part count? And progressive steering's cool too!

I would like to see this on the very first models, since this can be updated through software. But it would be neat if the first models did not have it, to compare it to ones that do in the future.

 

[C T Rick]

All of our toy drones, cars, boats , planes have had it for 50 years.

who remembers the gas powered planes that you held onto a dual corded paddle and spun in circles while controlling the pitch of the plane before you got dizzy and fell down.

Rick

 

[TyPope]

All of our toy drones, cars, boats , planes have had it for 50 years.

who remembers the gas powered planes that you held onto a dual corded paddle and spun in circles while controlling the pitch of the plane before you got dizzy and fell down.

Rick

LOL. I remember building one with balsa wood and heat shrink plastic covering for the wings. I don't remember ever flying it though... Those motors sucked to start.

 

[TyPope]

Steer by Wire is already on the market……Lexus has it. Great video below. Hope the CT has it.

All Tesla needs to do is improve on it to get progressive steering to make the yoke wheel work great. Tesla has applied for steer by wire patents. Don’t be surprised to see it.

youTube…”How Lexus Fixed Tesla’s Bad Idea”…Steer-By-Wire Yoke….
…Engineering Explained

We've seen pictures of the Cybertruck by the road and the suspension bits as well. Is there a way to tell in those pictures if it's steer by wire?

 

[Sonic]

Literally the last 3 seconds of this video show that the Pre-production model definitely has a steer-by-wire system. The front wheels are almost full-lock, whilst Franz is only making quarter-turns at the steering wheel.

I think we will see steer-by-wire in the production model, though as far as I'm aware, US law still requires a mechanical back-up steering column (which CT definitely has).



Can't see any reason why they'd go through all of this effort, and not offer steer-by-wire from the get-go.

 

[cvalue13]

Literally the last 3 seconds of this video show that the Pre-production model definitely has a steer-by-wire system. The front wheels are almost full-lock, whilst Franz is only making quarter-turns at the steering wheel.

Correct - production unit has SBW

You can bank that

I think we will see steer-by-wire in the production model, though as far as I'm aware, US law still requires a mechanical back-up steering column (which CT definitely has).

Not quite - the back-up system can be satisfied by either mechanical or a completely redundant electronic system

It is not clear yet whether the CT has a mechanical or electronic redundancy

 

[Sonic]

Not quite - the back-up system can be satisfied by either mechanical or a completely redundant electronic system

It is not clear yet whether the CT has a mechanical or electronic redundancy

The redundant electronic system is good news. Is there a link to that exact design rule you are able to provide? I'd be interested in reading.

There is a single hole in the firewall, on the drivers side. Size and position suggest it's designed for a steering column. Would be sweet if they don't even use it.

 

[cvalue13]

There is a single hole in the firewall, on the drivers side. Size and position suggest it's designed for a steering column. Would be sweet if they don't even use it.

that may be there merely to allow the column to pass through to the electronics.

otherwise:

https://www.cybertruckownersclub.com/forum/threads/steer-by-wire-confirmed.8563/post-155875

 

[JBee]

It would make sense that the rear steering of the CT is SBW, but does that mean the front one has to be SBW as well?

The easiest solution for redundancy for the rear steering would not be a secondary actuator or system, as much as a simple spring could be used to keep the rear wheels straight if not actuated by the SBW system. That would suffice to keep the vehicle operable if the front steering is also mechanical then no redundant systems needs to be used and the cost can be kept low.

BTW mechanical variable steering rate steering racks have been around for decades, and could be the reason why the CT front axle steers sharper the further you turn. It need not be SBW on the front for that, which in turn would explain the penetration hole through the firewall for the mechanical steering column. They might update this in the future.

In general "upgradability" could well form a major part of the design priorities, in that all of the Tesla models have been significantly upgraded over time, whilst essentially only keeping the exterior and interior look and functionality along the way. This is unconventional for OEM, in that the normal process is NOT to upgrade and exiting model, but rather replace with a new model.

I think having the rear 4WS SBW with front mechanical with variable rate, would suffice to get a full feature set. I don't think there is any major benefit to add SBW to the front as well this way, but it would add cost and complexity until front SBW becomes mainstream.

What is nearly more interesting is Brake by Wire. (BBW) This would also allow for steering inputs as well and in conjunction with a quad motor torque vectoring setup, would offer the most controllable and adaptable, actively controlled setup you can get. The ability to control torque applied for accelerating and decelerating per each individual wheel will allow for the most extreme of controlled manoeuvres possible.

A ABS or ESP traction control system on most cars can overcome the steering inputs presented by changes in steering angle. This is because the rotation speed of a wheel in relation to other wheel RPM's is what determines the rate of yaw, because the contact patch of the wheel is the amount of traction applied to the surface of the road that can change vehicle direction, not just the angle of steering that only changes the direction of rotation of the wheel first and only then rpm. A rally car doing a power slide around a corner is a good example of this, in that the car is not turning at the angle of the wheels themselves, but rather at the maximum angle afforded by the traction of the contact patch to the ground.

The main difference between ABS/ESP and BBW is that each individual wheel brake has it's own pressure modulation, instead of coming from a central brake cylinder, that then gets distributed though out the car to each wheel. This finer individual wheel control means much better braking performance on the limits of traction. ABS vehicles tend to brake slower in dry conditions than non-ABS, and this is mostly because the system dosen't react to varying forces fast enough, and that a locked wheel tyre has a higher coefficient of friction than a spinning one. (until the tread is gone) So the trick here is to keep the wheel loaded with so much braking torque that the tyre has maximum deformation to the point that rubber compound is removed uniformly on a still spinning tyre. Simply you want to brake as hard as the tyre will give maximum traction, which is also the point the tyre is essentially being "un-treaded". You can see this happen in real time in F1 racing when they brake into the corners.

Now if we combine this with QM and enough acceleration we have the ability to yaw the vehicle into a different direction than it is driving (within limits) which in turn means the QM/BBW setup is also the dominate mechanism for steering, especially in fringe or emergency situations. Basically tank turn, but incrementally whilst driving forwards. Potentially, this could also be used as a "substitute" redundancy steering mechanism for SBW, and would come at little to no extra cost as it uses the already existing systems, just adds another level of code to interact them.

 

[PilotPete]

It would make sense that the rear steering of the CT is SBW, but does that mean the front one has to be SBW as well?

The easiest solution for redundancy for the rear steering would not be a secondary actuator or system, as much as a simple spring could be used to keep the rear wheels straight if not actuated by the SBW system. That would suffice to keep the vehicle operable if the front steering is also mechanical then no redundant systems needs to be used and the cost can be kept low.

BTW mechanical variable steering rate steering racks have been around for decades, and could be the reason why the CT front axle steers sharper the further you turn. It need not be SBW on the front for that, which in turn would explain the penetration hole through the firewall for the mechanical steering column. They might update this in the future.

In general "upgradability" could well form a major part of the design priorities, in that all of the Tesla models have been significantly upgraded over time, whilst essentially only keeping the exterior and interior look and functionality along the way. This is unconventional for OEM, in that the normal process is NOT to upgrade and exiting model, but rather replace with a new model.

I think having the rear 4WS SBW with front mechanical with variable rate, would suffice to get a full feature set. I don't think there is any major benefit to add SBW to the front as well this way, but it would add cost and complexity until front SBW becomes mainstream.

What is nearly more interesting is Brake by Wire. (BBW) This would also allow for steering inputs as well and in conjunction with a quad motor torque vectoring setup, would offer the most controllable and adaptable, actively controlled setup you can get. The ability to control torque applied for accelerating and decelerating per each individual wheel will allow for the most extreme of controlled manoeuvres possible.

It is possible to have true SbW on the rear and not the front. Just mount the sensor on the steering shaft and route it to the computer and poof, Bobs your uncle. But the hole in the firewall could just be for the steering shaft to go through to the angle sensor. So I’m not certain that the hole is definitive in what it means. BbW on ICE cars is what is used for torque vectoring and traction control (on most cars). But with a multi motor electric, all you have to do is adjust the power flow to that motor. Less braking is better. On an axle with only 1 motor, brakes would be needed to adjust L/R power, but in a dual/triple, not F/R torque. Quads are their own thing. There are some high end sports cars that don’t use the brakes for torque vectoring, rather they use electronic diffs and manage the torque there.

I, personally, would love to see true SbW and 4wheel independent BbW on the CT. But that’s why I’m buying it, for all the tech toys.

 

[JBee]

It is possible to have true SbW on the rear and not the front. Just mount the sensor on the steering shaft and route it to the computer and poof, Bobs your uncle. But the hole in the firewall could just be for the steering shaft to go through to the angle sensor. So I’m not certain that the hole is definitive in what it means. BbW on ICE cars is what is used for torque vectoring and traction control (on most cars). But with a multi motor electric, all you have to do is adjust the power flow to that motor. Less braking is better. On an axle with only 1 motor, brakes would be needed to adjust L/R power, but in a dual/triple, not F/R torque. Quads are their own thing. There are some high end sports cars that don’t use the brakes for torque vectoring, rather they use electronic diffs and manage the torque there.

I, personally, would love to see true SbW and 4wheel independent BbW on the CT. But that’s why I’m buying it, for all the tech toys.

I don't know of a single car that effectively uses brakes for torque vectoring. This might be a sales slogan, but mechanically, it's hard to achieve with a normal hydraulic brake circuit. Most torque vectoring in ICE is through active clutch mechanisms in the drive-train for torque distribution, not brakes. Traction control, ABS/ESP etc yes, but that is not the same as torque vectoring.

Also there aren't many cars, let alone not expensive ones, that use BBW systems. This is a fairly recent development, and is the closest we have come to "brake torque vectoring", simply because a single main brake cylinder setup, as is common, doesn't have one wheel on and one wheel off, and can continuously vary anywhere in between them fast. That is because a typical system just pulses the pressure of the main brake line to the brake that needs modulation.

Imagine you have 50% main cylinder pressure, so two wheels is at 50%, one at 25%. How do you get the fourth to 55%, let alone 100%? BBW can have 10% brake pedal pressure, and 0-100% at any time it needs to. Pressurising a single main cylinder and transferring it hydraulically to each wheel has a much longer delay than a electronic solenoid actuator on the brake caliper itself. By the time it responds to the feedback loop, the modulation event can be over. That's why BBW stops faster, because the system adapts 100's times a second to available traction of that single tyre. The net average braking is therefore more overall, leading to shorter stopping distances. This effect gets multiplied if you start adding any type of turn or steering angle, or road surface irregularity.

Torque vectoring goes one step further than this though, in that with a QM and BBW it actively can modulate wheel rpm and torque to perfectly match available traction, but also inhibit traction loss in the first place by ensuring that no wheel is actually spinning at an un-commanded wheel speed. Each wheel turns at the speed it passes over the ground, and can produce torque in either direction as desired, taking into consideration the available traction available through those specific tyres in those conditions.

This is the equivalent of having a "differential lock" that normally forces you to go straight, but also forces you to go around a corner, like a tank turn but at speed. Dynamically, this also means that the vehicle is subject to cornering acceleration from the onset of the steering input (or from control), which reduces peak lateral accelerations and loss of traction sideways, and prior to suspension taking up any load and transferring load to the outside wheels which then in turn also reduces overall traction. Think of the old style tractors with separate left and right brakes. You can turn on a dime, regardless of the front steering angle. Now multiply that by 2 for 4 wheel torque vectoring.



Another avenue that is not only is the response time so fast, but you can also add some predictive ability into the mix as well, in that the car can learn and know what the rpm of each wheel should be, meaning the wheel RPM doesn't even break traction in the first place. It can even adjust driving dynamics between over/understeer depending on the road surface or conditions (rain/snow/gravel etc). Technically, the system is fast enough to even use wheel inertia to dampen suspension travel.

The other thing is that using the brakes, instead of motor torque (decelerate and accelerate) mean that you prematurely wear out the brakes for traction control purposes, with QM you don't as much. (which also leads to better braking performance overall and better lap times if that's what you are up to).

In any case if CT comes with QM and BBW and 4WS and active air-suspension, if they do it right we will see the best driving dynamics of any car, as each tyre at every corner will be given the best opportunity to perform to the max available traction. It's only let down will be it's total mass.

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