There's standards for control like MIL-STD-1472 which I'll bet this meets.
I'm sure none of them are "the highly redundant sensor fusion system with absurd levels of automation and sensing, the operator should not be able to notice any lag"
uhhh, 100ms isn't particularly stringent for a local system... nor should be the tolerance for the impact of control in a system that's literally at rest.
unless we're playing soccer / free-kicks, in which case, yeah, overengineer the hell out of it, sport.
ps, chapter 5 precisely specifies tolerances and minimums for things like latency of specific controls, for a control system for heavy machinery intended to be controlled by a human... and thanks for your input.
Is this even an issue? Presumably without a steer by wire system a human would not be able to turn the wheel this fast. Also the delay looks longer than it actually is because of the slow-mo. Say this is playing at 25% speed and it is delayed by 1/2 a second, that means at regular speed the delay is only 125ms.
1/8 of a second is terribly slow. Delays like that fuck up your perception/feedback loop. If you put on headphones, and listen to your own speech delayed by that amount of time, you can hardly speak (delayed auditory feedback). If you have to control a device that delays that much, you're prone to overreacting, and then entering a run-away correction cycle, which isn't nice in a heavy, fast moving machine.
Yeah, it's really not great. To be fair, though, in the dialup days, many of us learned to cope with that ping while still playing Quake 2 or whatever. You can adapt, it just takes a while, and you learn to lead your target. You can make similar adaptations to vehicle control (like playing a racing game on a really laggy old-school plasma TV), but it's not pleasant.
I really wouldn't want highway drivers in that monster truck to have any barriers to their reactions, especially with its nontraditional crumple zone :(
Power assist lets you turn a wheel with one finger at any ratio the manufacturer chooses... at most you'll get a lag in the assist but not in the mechanical movement (and I'd be amazed if that is perceptible with electric assist let alone hydraulic)
There isn't really any excuse for this.
It's hardly a performance car so perhaps it's not a big issue, but it really should not the there and should be fixed.
Because the steering ratio is variable, the movement shown in the video is about the equivalent of two full turns of a normal steering wheel. I tend to agree with the parent, it'd be hard for a human to equal this performance.
You know, I rewatched the video, and you convinced me.
There's not actually THAT much latency (delay between input and response). There IS some acceleration curve being applied (X degrees of input = X^Y degrees of steering, buffered over time), but that's totally different. It's probably safer this way vs suddenly jerking the actual wheels back and forth.
Steering backlash is always non-zero but for a new vehicle should be imperceptible. But that isn't a direct analogy for lag. With backlash, once you've taken it up it's gone. Any continued turn in the same direction translates to wheel movement without delay.
I agree with your observation, although it seems unpopular at the moment. It’s clear the video is slowed down and seeing how his hands respond at the end of his action, it looks like he’s throwing the wheel very quickly.
The tires start moving immediately, so it looks more like a limit in how quickly they change direction. It appears laggy because they don’t finish the movement when he does. They do respond right away when he shifts his arms a little in the middle of the video.
125ms is...horrendous. Electronic steering controls are part of my day job and usually you're going for about 5ms delay. If you're more than 10ms, it's a problem.
Traction control absolutely leads to a false sense of security, especially in hazardous conditions. However, steering lag is a bug, not a feature, and having your car go in the direction you point it is very important.
I think the tone of the tweet is off putting, and while the lag doesn’t seem totally unsafe, it does look a bit poor. That said, how much play is in a normal steering system, powered or otherwise?
The most ridiculous thing about the Cybertruck is that it is completely illegal in the EU. For good reason IMO and it's sad that the US allows this risk for pedestrians on the roads.
It would be even worse in the EU. Here in America, both our pedestrians and our cars are larger, so we’ll at least leave a mark when that monstrosity hits us on autopilot.
I’m only half joking. I’d be worried in the EU because they don’t drive around mostly in SUVs like we do. A cybertruck versus a panda would not go well.
Many jurisdictions in the US have safety regulations specifically around steering. In some jurisdictions it's illegal to drive a car on public roads with steering that has no mechanical connection to the steering wheel. Some areas have a minimum steering wheel diameter that's larger than the cybertruck steering wheel's minor diameter. Some areas have laws requiring a minimum (multiple...) number of turns lock-to-lock. Many areas require your steering to be operable in the event of power loss (I'd bet that everyone on or near a road would like that too). DMV's and police agencies sometimes regulate what they independently perceive as safety problems regardless of law, if someone with the means to declare internal policy gets the urge.
And that's for all cars operating on public roads, not just registered, in an area. It might be legal to drive a cybertruck where one lives, but not in a neighboring city or state. Moving fast and ignoring regulations on Tesla's part only works for their customers until regulatory agencies encounter a reason to pay attention.
Is this actually control lag or just an authority limit? If the car takes that long to respond to every control input, it's a serious problem. If it's just that the hydraulics can't move the wheel through full travel as fast as the control can be moved, it's a non-issue. My guess, based on the shitposty tone of the linked tweet, is the latter.
Needless to say, if you put someone at the wheel of a vehicle with regular power assist steering, the wheels aren't going to move any faster.
No, "the problem" as described is control lag, and decoupled input simply is not the same thing. What you describe as "far from a non-issue" is a characteristic shared by literally every fly/drive-by-wire system. If you trust your Airbus to get you to your destination, you can trust a Cybertruck[1] to get you home. Or if you don't, you need to come to the debate with evidence and not misleading garbage tweets like this one.
[1] Or others. Tesla is not the first company to offer steer-by-wire, just the first to engender this kind of nonsense debate about every decision they make.
Our 2005 DARPA Grand Challenge vehicle, a Polaris Ranger ATV, looked like that in manual mode. The steering wheel was drive by wire, and used a simple PI controller.
Stationary, with the steering system fighting static friction, the normal P value useful for driving is too low, so there's lag. The I term cranks up the force until the error goes to 0, but that takes time. Our remote dashboard had two pointers on the steering meter - commanded steering angle and actual steering angle. We could watch the lag. Half a second of lag was OK, because we didn't do any aggressive maneuvers. Manual mode was just for positioning the vehicle before going autonomous.
That slowdown at the end of the Tesla video looks like normal operation of a PI controller.
Does Tesla have steering force feedback? If the steering wheel is leading the wheels, the steering wheel should be pushing back on the driver if there's significant error.
I think the cybertruck is a piece of garbage but people like to say things like this authoritatively on the internet and it is wrong.
I like cars, I have built and raced cars. I have owned sports cars, boring hybrids, and a Tesla. I have tuned ECUs and adjust BCMs… cars do not behave as linearly and directly as a lot of Internet engineers seem to think they do.
If you watch closely in this video, the steering wheel turning and the wheel starting to turn happen almost instantaneously, there is no initial input lag. The lag is between the steering wheel and wheel reaching center, and that’s dictated by an intentional acceleration curve. This is what I would have expected in a steer-by-wire system.
There are things worth complaining about with steer-by-wire and I don’t think this is one of them.
I am extremely picky about those things, it would drive crazy. My pet peeve was the Audi S3 I had as rental once, this minuscule, barely recognicable, delay between kicking down the pedal and the car accelerating drove me crazy. I prefer slow, but immediate acceleration.
Cool car background by the way! I just wonder why using steer-by-wire, what's wrong with modern power steering?
> My pet peeve was the Audi S3 I had as rental once, this minuscule, barely recognicable, delay between kicking down the pedal and the car accelerating drove me crazy.
There could be a number of reasons for this but no modern car has a direct connection between the pedal and the throttle bodies, so it isn’t inherent to drive-by-wire. It can probably be tuned out of the S3 in software pretty easily. I haven’t driven one so I won’t claim there is no lag in the Cybertruck’s steering, but I find it pretty unlikely there is observable lag in the initial response compared to other vehicles in its weight class, which aren’t particularly responsive.
The three reasons I think are most relevant to Tesla:
1. Packaging - removing the steering column is a pretty dramatic reduction in the number of parts in the front of the car and makes it possible to reuse that space. It may make it easier to design the front crumple zone as well.
2. Extreme variable steering ratios - you can tune the steering ratios much further with a fully by-wire system. In a large vehicle it makes it easier to maneuver at low and high speeds with less effort for the driver.
3. If autopilot were ever to come to fruition, the steering wheel won’t have to move while autopilot turns the car.
Especially three seems hihhly risky: if the driver has to take over, he has no clue of where the wheels are pointing at. But since FSD wont matetialize for at least another decade, it is not that pressing.
Regarding the S3, and Audi's in general, I know that I am one of the few people I know who is really annoyed by that.
Lots of cars throughout the last two decades have suffered from latent issues as a result of new drive by wire implementations. It was very frustrating in some models from early 2000s where the electronic throttle modules where severely delayed. You'd push the pedal to the floor and get no immediate feedback. Terrifying when you're trying to get out of the way.
I've had issues with throttle-by-wire but not so much latency as much as the traction control nannies telling me how to drive. First time I had this happen in a '14 Tundra it scared the crap out of me, because it works by cutting throttle to the drive tires if it detects loss of traction. Then it seems like the vehicle is not responding to throttle inputs until the computer decides traction has been regained.
I get that it's "safer" for your typical driving conditions, but I'd imagine trying to get out of the way in a hurry it could be a problem... Knowing that's the case now, I kind of expect it, so it's changed my driving habits slightly and has made me plan ahead more than normal.
But I can't imagine how actual input latency would feel after that experience.
So if you operate a bicycle you might understand what's actually going on here a bit more.
The first parts of the movement are actually quite responsive but don't result in a huge change.
If the wheels moved as the drive dictated the car would flip over. You can't just magically make all the forward momentum go lateral without relying on road and tire friction to get the job done. This can hit limits / you just end up skidding the tires and going ass over end instead of turning because you yanked the wheels too dramatically.
It would be like riding a bicycle and then turning the handlebars completely to one side while going at a good pace forward.
You could argue why isn't the car just doing it because they're at a standstill and it should be safe to do so? It's probably a sane default in case there are no sensors / no velocity reading / etc.
> If the wheels moved as the drive dictated the car would flip over.
Do you mean “… at high speed?” To me, it looks like the person just wants this car to steer the way literally every other car does. Your bicycle analogy — yes, that’s how they work, so pretty quickly you learn how to do that.
The demo shows the person stearing couldn't apply urgency in directing the wheel, sounds dangerous. Onus should be on the driver being capable of making the steering angle appropriate for the conditions, defending eventually consistent steering is comical, now drivers must account for where and by what speed the wheel angle reaches the desired position?
> defending eventually consistent steering is comical
That's how things work though. Momentum and material strain mean that nothing reacts instantly, and that changes with your speed, steering angle, and rate of change in speed and steering angle. So yes, all drivers must account for the where and by what speed the wheel angle reaches the desired position.
I'd honestly class that as reductio ad absurdum, quantum mechanics dictates it is a probability my car might spontaneous become a pink elephant.
I'm all for evidence showing the latency shown on the video is comparable to competing implementations, but I'm not interested in lazy arguments that all momentum is eventually consistent as a defence.
> You could argue why isn't the car just doing it because they're at a standstill and it should be safe to do so? It's probably a sane default in case there are no sensors / no velocity reading / etc.
So the argument is that even with critical sensors offline or not providing meaningful data, the automation should continue to operate as normal? I believe Boeing has said much the same. The outcomes they've had by it lead me to doubt the merit of the argument.
The wheels move exactly as the driver wants in any vehicle with a mechanical steering rack. It's not a problem. Lag due to poor drive-by-wire implementation however is most definitely a problem and not a small one, it's a significant safety hazard.
If I try to turn the front wheel of my bike too far left or right it does not let me. Further, this is accomplished by a rubber bumper that continues to push for a short time after I let up, but it would be absurd to call this "lag." Normal operation of the bicycle never gets close to those limits.
The question is whether this video is showing typical system lag -- in which case, yeah, I agree, it's a problem -- or whether it is showing limiting behavior in which case getting upset about it makes as much sense as getting upset over the rubber bumpers on my bike.
I am not upset by a bike behavior because I know exactly what my wheels are doing just by holding the bars. Same in a mechanical steering rack. This here seems more like a guessing game
>If I try to turn the front wheel of my bike too far left or right it does not let me.
Not sure what you're referring to here - I've got multiple bicycles and the headset bearing allows them to spin around 360 degrees, the only thing preventing them from going further is the cables and hydraulic hoses.
>Further, this is accomplished by a rubber bumper that continues to push for a short time after I let up
What bumper do you mean? Your handlebars, stem, and fork should be moving as a solid unit, with minimal deformation under any reasonable conditions. There's very little elasticity in the system, perhaps the biggest source is just the spokes (or the grips if they're quite thick). The behavior exhibited in the video is way more than any properly operating bicycle.
Your bike is different than mine. Shrug. It is not beyond my imagination to imagine the free-spinning mechanism you have described, so I cannot imagine that it is beyond yours to imagine a bumper. Try, and you will succeed.
I seriously have no idea where such a bumper would even go, let alone what it would look like. And it's not my bike, it's dozens of ones that I have owned or seen. It's also far easier to imagine the lack of something rather than the existence of something you've never even heard of. A simple link to a photo would be quite helpful.
I did say "wheels", which generally speaking means the rim. Yes, I'm well aware of tire deformation and contact patch mechanics, but that's not the issue here - the rims on the truck are not moving in sync with the wheel. It's just not acceptable.
The speed of sound in steel and roughly 1m of steering column put the theoretical minimum latency at 0.2ms. Manufacturing tolerances and material strain put minimum bounds on accuracy as well. Your entire suspension, down to the rigidity of the individual linkages, influences the steering of your vehicle.
> Yes, I'm well aware of tire deformation and contact patch mechanics, but that's not the issue here...
I think it's very relevant to know that cars already take the direction of the tires/rims/wheel as more of a suggestion. The "tightness" of the steering and the suspension varies drastically between vehicles. So what is the issue here? How it drives. I don't have one, but a common comment I've found in reviews is that it's "too sensitive." I think this is an imagined problem.
You're correct that nothing can move instantaneously, at a maximum it's bounded by the speed of sound in the material. But can you detect a 0.2ms delay? Probably no human can. What about a 2ms delay? Potentially some people can. What about a 20ms delay? Probably, although it's still very small.
Perhaps saying that the wheels move "exactly" as the driver intends in a rack and pinion system is too absolute, but if you can't see or feel this delay then I'd argue that to the human driving it's irrelevant. You can see the lag in the video, which admittedly is slowed down, but if we assume the original frame rate was 60fps then there's a minimum of a 16.7ms lag and I'd estimate it's at least 3-4 frames so more like 50.0-66.7ms, which is absolutely noticeable. Why should we accept performance which is clearly worse than a mechanical system? This is a delay that exists on top of all the other factors you've mentioned, not in lieu of them. It casts doubts on the functional safety of the system.
> The "tightness" of the steering and the suspension varies drastically between vehicles
I could push your argument forward a bit more: the same vehicle can have tightness change as speeds goes up: electric power assistance progressively reduces as speed goes up. Why? because electric power steering is so powerful that it would be too easy to quickly turn wheels at speed. So the helper reduces, making it harder to turn the wheel in the same way that it became harder before power steering because physics.
I needs more force, but the lag doesn't change, and neither is the gear reduction ratio, nor the absolute angle of the steering wheel to the actual angle of the wheels relative to the body.
> I think it's very relevant to know that cars already take the direction of the tires/rims/wheel as more of a suggestion.
I see this vehicle as introducing a fundamental breaking change in how automobiles are being operated:
a) previously: you the driver physically control the car parts. You drive, operating the car by transforming high level intent to low level commands. You're the pilot sitting at the helm and your job is made easier with some helpful systems (ABS, ESP, cruise control, automated transmission, lane assist, what have you) that you can shunt.
b) this vehicle: you communicate intention "I want to go in this general direction" / "Set a course to Rigel VII. Maximum warp" and someone else follows your instruction and drives the car for you. The physics is abstracted away. You're not the pilot, you're the captain, and captains don't go to helm.
Up til now we've seen a) being progressively automated, working up towards full automation.
This vehicle instead appears to be designed to be designed downwards from full automation, offering a degraded mode of operation from full automation that looks like a) but is fundamentally different from a).
You can't shunt systems because that would prevent the actual pilot from operating the vehicle. In fact the pilot could very well do things that would be surprising and you would not be able to override it because your role is higher up.
I fully expect this design to lead to the cap'n turning the wheel slightly left but the pilot "refuses" to comply and slaloms around a bunch of pedestrians.
Yes there's a bit of slack and elasticity all the way including in metal parts, not just in tires. Still, even though the tire tread doesn't move right away the moving rims are immediately exerting force on the tire interior, and thus there's an instant converse force from the tire interior which resists the movement.
In any case, this vehicle has rims and tires; what's being discussed here only adds lag to the existing system, which appears to be several orders of magnitude higher than the above physical process.
But what's apparently worse here is that there's no link (whether physical or digital): the video shows the driver has moved the steering device all the way to lock yet the wheels are only halfway through and then continue moving towards lock in spite of the steering device being completely still.
> The first parts of the movement are actually quite responsive but don't result in a huge change.
> If the wheels moved as the drive dictated the car would flip over.
Non drive by wire cars react instantly by virtue of having wheels and steering physically linked. One can tip over such a car in the same way as you describe, the only thing preventing it is a) physics which makes it a bit harder to apply enough force and b) physics which gives the driver feedback that they're doing it wrong.
Which leads us to the crux of the issue here: this DBW implementation decouples the steering device not just physically in action but in dynamics and feedback as well: It's literally a joystick masqueraded as a steering wheel, with apparently little to no force feedback, and very obviously force feedback completely decorrelated from the actual angle of the wheels.
Taking a side road through the bicycle example: one doesn't turn a bicycle by turning the handlebar, one turns a bicycle by angling the whole apparatus, and the front end follows due to its geometry.
The same principle applies to a car's front suspension: the geometry of it makes it resist being turned, which provides quintessential feedback to safe operation. Without this, a critically important signal is removed. A second one is removed as there is jo way to know how angled wheels are relative to the car's body. Throw in latency into the mix and you get a surefire way to create an overcorrection feedback loop and be completely unable to react in even slightly non-ideal situations.
This means that for any sort of safety that should be by design of the chassis and suspension the vehicle relies entirely on ESP, when ESP should be a last resort fallback when the normal mode of operation fails. Instead there is no fallback nor redundancy and ESP MUST work or this vehicle becomes a death machine at the slightest sideway skid that would be perfectly manageable otherwise, even without ESP.
> sane default
This means the vehicle changes its dynamic reaction to driver input. Training aircraft pilots about normal law vs alt law is already quite something, I don't think training drivers about similar things is going to be very successful.
Would it be possible to force the front wheels to turn fast enough when the truck reaches high speed to cause an accident?
That's a bit morbid, but if you can hack the computer or manipulate sensor input to change the car comportement, it'll be easier, more effective and more stealthy for assassination.
I’ve watched many reviews of the cybertruck, including people that have driven thousands of miles with it, and I’ve not heard a single one of them complain about the steering or lag.
So my guess is this tweet with one short video and no additional evidence or reasoning behind their claim is wrong.
here it is, folks. we finally have cars with the shit design where you just shove random components that add lag in because you're too lazy / uneducated to understand your 'stack' or well-established science (such as the fact that input lag matters and the more of it you have, the more mistakes the human makes, even when the total lag is below the human 'reaction time'). the market is driven by who has the most clout, regardless of whether your product is sound. this is also why i don't use drive-by-wire, it was just obvious that they'll eventually mess this up (even if this tweet is not accurate).
The vehicle isn't moving. It's a several ton vehicle. No matter the rate of turn, it has no forward momentum to assist the turn. This is the same reason that non-power-assisted steering vehicles are easy to turn at high speed, and difficult at low/no speed. It takes more energy. This means the quicker (in terms of acceleration and velocity) you turn the drive wheels the more energy it takes and the more wear and tear it places on the steering components and tires.
Even if this wasn't by design and is a limit of the "power" of the power steering system unable to "keep up", so what? Try going 0.5mph and see how it feels.
Also notice its not LAG. It starts turning THE MOMENT you turn the steering wheel, it's rate of change just isn't the same. That's not latency. The vehicle still turns the wheels when you ask it to, even when stopped. In what scenario do you need a stopped vehicles tires to steer from lock to lock in under 3 seconds?
There is plenty to complain about the cybertruck. This aint it, chief.
Every car for the last 150 years has had mechanical connection from the steering wheel to the tires and nobody is talking about the reliablity and safety concerns. The absolute state of hacker news.
78 comments
[ 2.8 ms ] story [ 132 ms ] threadThere's standards for control like MIL-STD-1472 which I'll bet this meets.
I'm sure none of them are "the highly redundant sensor fusion system with absurd levels of automation and sensing, the operator should not be able to notice any lag"
unless we're playing soccer / free-kicks, in which case, yeah, overengineer the hell out of it, sport.
ps, chapter 5 precisely specifies tolerances and minimums for things like latency of specific controls, for a control system for heavy machinery intended to be controlled by a human... and thanks for your input.
Try it yourself here to see how bad that feels: https://www.skytopia.com/stuff/lag.html
That page also links to a great video on what it's like on a touchscreen: https://www.youtube.com/watch?v=vOvQCPLkPt4
I really wouldn't want highway drivers in that monster truck to have any barriers to their reactions, especially with its nontraditional crumple zone :(
There isn't really any excuse for this.
It's hardly a performance car so perhaps it's not a big issue, but it really should not the there and should be fixed.
There's not actually THAT much latency (delay between input and response). There IS some acceleration curve being applied (X degrees of input = X^Y degrees of steering, buffered over time), but that's totally different. It's probably safer this way vs suddenly jerking the actual wheels back and forth.
The tires start moving immediately, so it looks more like a limit in how quickly they change direction. It appears laggy because they don’t finish the movement when he does. They do respond right away when he shifts his arms a little in the middle of the video.
Same sort of thing with people that complain about iterm being too laggy.
I’m only half joking. I’d be worried in the EU because they don’t drive around mostly in SUVs like we do. A cybertruck versus a panda would not go well.
And that's for all cars operating on public roads, not just registered, in an area. It might be legal to drive a cybertruck where one lives, but not in a neighboring city or state. Moving fast and ignoring regulations on Tesla's part only works for their customers until regulatory agencies encounter a reason to pay attention.
Needless to say, if you put someone at the wheel of a vehicle with regular power assist steering, the wheels aren't going to move any faster.
[1] Or others. Tesla is not the first company to offer steer-by-wire, just the first to engender this kind of nonsense debate about every decision they make.
Our 2005 DARPA Grand Challenge vehicle, a Polaris Ranger ATV, looked like that in manual mode. The steering wheel was drive by wire, and used a simple PI controller. Stationary, with the steering system fighting static friction, the normal P value useful for driving is too low, so there's lag. The I term cranks up the force until the error goes to 0, but that takes time. Our remote dashboard had two pointers on the steering meter - commanded steering angle and actual steering angle. We could watch the lag. Half a second of lag was OK, because we didn't do any aggressive maneuvers. Manual mode was just for positioning the vehicle before going autonomous.
That slowdown at the end of the Tesla video looks like normal operation of a PI controller.
Does Tesla have steering force feedback? If the steering wheel is leading the wheels, the steering wheel should be pushing back on the driver if there's significant error.
I like cars, I have built and raced cars. I have owned sports cars, boring hybrids, and a Tesla. I have tuned ECUs and adjust BCMs… cars do not behave as linearly and directly as a lot of Internet engineers seem to think they do.
If you watch closely in this video, the steering wheel turning and the wheel starting to turn happen almost instantaneously, there is no initial input lag. The lag is between the steering wheel and wheel reaching center, and that’s dictated by an intentional acceleration curve. This is what I would have expected in a steer-by-wire system.
There are things worth complaining about with steer-by-wire and I don’t think this is one of them.
Cool car background by the way! I just wonder why using steer-by-wire, what's wrong with modern power steering?
There could be a number of reasons for this but no modern car has a direct connection between the pedal and the throttle bodies, so it isn’t inherent to drive-by-wire. It can probably be tuned out of the S3 in software pretty easily. I haven’t driven one so I won’t claim there is no lag in the Cybertruck’s steering, but I find it pretty unlikely there is observable lag in the initial response compared to other vehicles in its weight class, which aren’t particularly responsive.
The three reasons I think are most relevant to Tesla:
1. Packaging - removing the steering column is a pretty dramatic reduction in the number of parts in the front of the car and makes it possible to reuse that space. It may make it easier to design the front crumple zone as well.
2. Extreme variable steering ratios - you can tune the steering ratios much further with a fully by-wire system. In a large vehicle it makes it easier to maneuver at low and high speeds with less effort for the driver.
3. If autopilot were ever to come to fruition, the steering wheel won’t have to move while autopilot turns the car.
Regarding the S3, and Audi's in general, I know that I am one of the few people I know who is really annoyed by that.
I get that it's "safer" for your typical driving conditions, but I'd imagine trying to get out of the way in a hurry it could be a problem... Knowing that's the case now, I kind of expect it, so it's changed my driving habits slightly and has made me plan ahead more than normal.
But I can't imagine how actual input latency would feel after that experience.
Just no road feedback...
The first parts of the movement are actually quite responsive but don't result in a huge change.
If the wheels moved as the drive dictated the car would flip over. You can't just magically make all the forward momentum go lateral without relying on road and tire friction to get the job done. This can hit limits / you just end up skidding the tires and going ass over end instead of turning because you yanked the wheels too dramatically.
It would be like riding a bicycle and then turning the handlebars completely to one side while going at a good pace forward.
You could argue why isn't the car just doing it because they're at a standstill and it should be safe to do so? It's probably a sane default in case there are no sensors / no velocity reading / etc.
By the way, if this is true, it is beyond stupid...
Do you mean “… at high speed?” To me, it looks like the person just wants this car to steer the way literally every other car does. Your bicycle analogy — yes, that’s how they work, so pretty quickly you learn how to do that.
The demo shows the person stearing couldn't apply urgency in directing the wheel, sounds dangerous. Onus should be on the driver being capable of making the steering angle appropriate for the conditions, defending eventually consistent steering is comical, now drivers must account for where and by what speed the wheel angle reaches the desired position?
That's how things work though. Momentum and material strain mean that nothing reacts instantly, and that changes with your speed, steering angle, and rate of change in speed and steering angle. So yes, all drivers must account for the where and by what speed the wheel angle reaches the desired position.
I'm all for evidence showing the latency shown on the video is comparable to competing implementations, but I'm not interested in lazy arguments that all momentum is eventually consistent as a defence.
It's a vehicle you can buy right now, and this clip comes from a review (thanks rainbowzootsuit).
https://www.youtube.com/watch?v=TeqE1kOO3dE&t=709s
So the argument is that even with critical sensors offline or not providing meaningful data, the automation should continue to operate as normal? I believe Boeing has said much the same. The outcomes they've had by it lead me to doubt the merit of the argument.
If I try to turn the front wheel of my bike too far left or right it does not let me. Further, this is accomplished by a rubber bumper that continues to push for a short time after I let up, but it would be absurd to call this "lag." Normal operation of the bicycle never gets close to those limits.
The question is whether this video is showing typical system lag -- in which case, yeah, I agree, it's a problem -- or whether it is showing limiting behavior in which case getting upset about it makes as much sense as getting upset over the rubber bumpers on my bike.
Not sure what you're referring to here - I've got multiple bicycles and the headset bearing allows them to spin around 360 degrees, the only thing preventing them from going further is the cables and hydraulic hoses.
>Further, this is accomplished by a rubber bumper that continues to push for a short time after I let up
What bumper do you mean? Your handlebars, stem, and fork should be moving as a solid unit, with minimal deformation under any reasonable conditions. There's very little elasticity in the system, perhaps the biggest source is just the spokes (or the grips if they're quite thick). The behavior exhibited in the video is way more than any properly operating bicycle.
Your rims might, your tires don't. Check out about halfway down this page:
https://ciechanow.ski/bicycle/
If they don't something is broken.
>your tires don't.
I did say "wheels", which generally speaking means the rim. Yes, I'm well aware of tire deformation and contact patch mechanics, but that's not the issue here - the rims on the truck are not moving in sync with the wheel. It's just not acceptable.
The speed of sound in steel and roughly 1m of steering column put the theoretical minimum latency at 0.2ms. Manufacturing tolerances and material strain put minimum bounds on accuracy as well. Your entire suspension, down to the rigidity of the individual linkages, influences the steering of your vehicle.
> Yes, I'm well aware of tire deformation and contact patch mechanics, but that's not the issue here...
I think it's very relevant to know that cars already take the direction of the tires/rims/wheel as more of a suggestion. The "tightness" of the steering and the suspension varies drastically between vehicles. So what is the issue here? How it drives. I don't have one, but a common comment I've found in reviews is that it's "too sensitive." I think this is an imagined problem.
Perhaps saying that the wheels move "exactly" as the driver intends in a rack and pinion system is too absolute, but if you can't see or feel this delay then I'd argue that to the human driving it's irrelevant. You can see the lag in the video, which admittedly is slowed down, but if we assume the original frame rate was 60fps then there's a minimum of a 16.7ms lag and I'd estimate it's at least 3-4 frames so more like 50.0-66.7ms, which is absolutely noticeable. Why should we accept performance which is clearly worse than a mechanical system? This is a delay that exists on top of all the other factors you've mentioned, not in lieu of them. It casts doubts on the functional safety of the system.
I could push your argument forward a bit more: the same vehicle can have tightness change as speeds goes up: electric power assistance progressively reduces as speed goes up. Why? because electric power steering is so powerful that it would be too easy to quickly turn wheels at speed. So the helper reduces, making it harder to turn the wheel in the same way that it became harder before power steering because physics.
I needs more force, but the lag doesn't change, and neither is the gear reduction ratio, nor the absolute angle of the steering wheel to the actual angle of the wheels relative to the body.
> I think it's very relevant to know that cars already take the direction of the tires/rims/wheel as more of a suggestion.
I see this vehicle as introducing a fundamental breaking change in how automobiles are being operated:
a) previously: you the driver physically control the car parts. You drive, operating the car by transforming high level intent to low level commands. You're the pilot sitting at the helm and your job is made easier with some helpful systems (ABS, ESP, cruise control, automated transmission, lane assist, what have you) that you can shunt.
b) this vehicle: you communicate intention "I want to go in this general direction" / "Set a course to Rigel VII. Maximum warp" and someone else follows your instruction and drives the car for you. The physics is abstracted away. You're not the pilot, you're the captain, and captains don't go to helm.
Up til now we've seen a) being progressively automated, working up towards full automation.
This vehicle instead appears to be designed to be designed downwards from full automation, offering a degraded mode of operation from full automation that looks like a) but is fundamentally different from a).
You can't shunt systems because that would prevent the actual pilot from operating the vehicle. In fact the pilot could very well do things that would be surprising and you would not be able to override it because your role is higher up.
I fully expect this design to lead to the cap'n turning the wheel slightly left but the pilot "refuses" to comply and slaloms around a bunch of pedestrians.
In any case, this vehicle has rims and tires; what's being discussed here only adds lag to the existing system, which appears to be several orders of magnitude higher than the above physical process.
But what's apparently worse here is that there's no link (whether physical or digital): the video shows the driver has moved the steering device all the way to lock yet the wheels are only halfway through and then continue moving towards lock in spite of the steering device being completely still.
> If the wheels moved as the drive dictated the car would flip over.
Non drive by wire cars react instantly by virtue of having wheels and steering physically linked. One can tip over such a car in the same way as you describe, the only thing preventing it is a) physics which makes it a bit harder to apply enough force and b) physics which gives the driver feedback that they're doing it wrong.
Which leads us to the crux of the issue here: this DBW implementation decouples the steering device not just physically in action but in dynamics and feedback as well: It's literally a joystick masqueraded as a steering wheel, with apparently little to no force feedback, and very obviously force feedback completely decorrelated from the actual angle of the wheels.
Taking a side road through the bicycle example: one doesn't turn a bicycle by turning the handlebar, one turns a bicycle by angling the whole apparatus, and the front end follows due to its geometry.
The same principle applies to a car's front suspension: the geometry of it makes it resist being turned, which provides quintessential feedback to safe operation. Without this, a critically important signal is removed. A second one is removed as there is jo way to know how angled wheels are relative to the car's body. Throw in latency into the mix and you get a surefire way to create an overcorrection feedback loop and be completely unable to react in even slightly non-ideal situations.
This means that for any sort of safety that should be by design of the chassis and suspension the vehicle relies entirely on ESP, when ESP should be a last resort fallback when the normal mode of operation fails. Instead there is no fallback nor redundancy and ESP MUST work or this vehicle becomes a death machine at the slightest sideway skid that would be perfectly manageable otherwise, even without ESP.
> sane default
This means the vehicle changes its dynamic reaction to driver input. Training aircraft pilots about normal law vs alt law is already quite something, I don't think training drivers about similar things is going to be very successful.
That's a bit morbid, but if you can hack the computer or manipulate sensor input to change the car comportement, it'll be easier, more effective and more stealthy for assassination.
Driving Tesla Cybertruck - Overhyped or the Pickup Reinvented?
https://www.youtube.com/watch?v=TeqE1kOO3dE
From about 10m into the video.
https://www.youtube.com/watch?v=TeqE1kOO3dE&t=709
So my guess is this tweet with one short video and no additional evidence or reasoning behind their claim is wrong.
this topic has been beaten to death throughout all aspects of computing, it always goes like this:
1. someone complains about input lag, because he feels it and it's annoying and prohibitive
2. other people who are slow and / or have misconfigured systems with such worse problems that they don't notice this disagree
3. 7 years later its proven to a wider audience that the lag is there and all the people who said it was there were right
4. the company sells an all new "low input lag" model (which doesn't actually require any money to implement, aside from a few hours dev time)
Even if this wasn't by design and is a limit of the "power" of the power steering system unable to "keep up", so what? Try going 0.5mph and see how it feels.
Also notice its not LAG. It starts turning THE MOMENT you turn the steering wheel, it's rate of change just isn't the same. That's not latency. The vehicle still turns the wheels when you ask it to, even when stopped. In what scenario do you need a stopped vehicles tires to steer from lock to lock in under 3 seconds?
There is plenty to complain about the cybertruck. This aint it, chief.
Every car for the last 150 years has had mechanical connection from the steering wheel to the tires and nobody is talking about the reliablity and safety concerns. The absolute state of hacker news.