Self-Driving Cars Are Dangerously Confused By LED Lights

This video is sponsored by Merck, a science and technology company. Find out how curiosity can change our future: www.merckgroup.com/en/worlds-... #alwayscurious
LED lights can look like they're doing weird things when viewed through a digital camera. It's all to do with the frame rate of the camera and the duty cycle of the LED. It's a real problem for autonomous vehicles. Self driving cars analyse footage from cameras to makes driving decisions that affect road safety. Under the right conditions a break light can even look like a turn signal! So what's the solution?
The image of the car from the thumbnail is by Michael Shick: commons.wikimedia.org/wiki/Fi...
The shrug emoji from the thumbnail is by EmmanuelCordoliani: commons.wikimedia.org/wiki/Fi...
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[@arcanics1971]

"...but a BMW driver would never do that so it must be an issue with a camera." Oh you!

[@marcoconci7867]

That got me😂😂

[@tashkiira7838]

I do hope it's a case of Steve teasing people. Because the 'BMW turn signal installers are the people who feel most useless in the world' jokes have been around for a long time..

[@richardsmith507]

April Fool?

[@MjkL1337]

LMAO i laughed so hard when he said that

[@friddevonfrankenstein]

It's hilarious just how many people notice this pretty subtle sidenote :D There's a joke in german (and probably other languages as well): If you feel worthless and unimportant, think of the poor souls who put the turning signals on BMWs.

[@JoseluPicks]

"I'm not saying turn lights in UK are better... I'm implying it." "A BMW driver would never change lanes without turn lights" Hell, I love bitchy Steve.

[@dan_]

You missed the dig at Apple too.

[@TechyBen]

@Audiocronic Are you a BMW driver?

[@Parax77]

"If it's really expensive to fix the bug, you could just ignore it, and they'll jump ship to android..."

[@xenon5066]

@Audiocronic I'll forego the privilege of using an indicator if I could have a BMW

[@gentleben4770]

I just got a BMW, turns out people behave poorly to bmw drivers. The only way I can get out into traffic now is to fit the stereotype

[@JonnesTT]

I love how much pure unfiltered sass is in this video XD "I'm not saying our system is better, I'm just heavily implying it" "A BMW driver would never do that" Is that what you call British humor? :D

[@Bennatte]

The Android one too xD

[@seanleith5312]

Whoever came up with this stupid self driving car idea should be killed for stupidity. This is stupidest idea I have ever heard of.

[@MrFlarespeed]

@@seanleith5312 whoever came up with this humans driving cars idea should be killed for their stupidity. 1.35 million people are killed by human drivers each year.

[@KOZMOuvBORG]

@@MrFlarespeed Agree, at least the self-driving car employs some kind of logic

[@KOZMOuvBORG]

@@seanleith5312 Since we had cars, humans have been striving to be ever more stupid driving them

[@hellelujahh]

6:40 "But it's not like an edge-case bug in a mobile phone, for example, where if it's really expensive to fix the bug, you can just ignore it, 'cause it's only affecting a handful of people, and they'll probably just jump ship to Android" ❤️ Subtlety is what catches you off guard, that's when you end up at the burn ward 😉

[@rizwanmunir224]

What I love is that it's a dig at both fanboys really

[@iphgfqweio]

Woha, watch out, here comes Steve Mould administering sick burns left and right.

[@Azivegu]

He would indicate them coming, but the camera is faulty, of course

[@mitchkovacs1396]

4:30 sick BMW burn

[@bluebaconjake405]

Mitch Kovacs Lmao, noticed that too

[@paulbelson2236]

Hmm. What's the sample size, Steve?

[@gubunki]

6:42 apple burn too XD

[@officer_baitlyn]

True tho

[@dezimal9143]

Till this point, I didn't know it was international "meme".

[@luke_fabis]

The thing that annoys me most about PWM brightness control is that when you’re in a situation where you have to move your eyes quickly, you don’t get clean afterimage trails as you would with voltage-based brightness control - rather, your field of view is covered with a jumble of dots and patches. I find that both annoying and disorienting - my eyes adjust a moment later, but as I move them, it feels almost like stutter due to dropped frames, except in real life. And of course, if I’m moving my eyes a lot, it’s almost always because there’s a lot of information to take in. It’s literally the worst time to get thrown off. For example, maybe I want to change lanes, except traffic is dense but moving quickly, and road conditions aren’t great. If we can’t outright ban PWM for safety-critical lights, there at least needs to be a mandate to introduce some kind of hysteresis. Maybe introduce a phosphor with just enough enough persistence to smooth out the blips, on the order of about 30 ms for a 50 Hz frequency. There’d be good overlap even with the lowest duty cycles.

[@miles11we]

The phosfor idea is a really good one

[@JMMC1005]

PWM is fine if it's fast enough - a few kHz at least. But so often it's far, far slower and visible.

[@andrewaronson3364]

you are transferring the time information to the spacial domain. you should be proud

[@andrewaronson3364]

@@fayenotfaye probably not. he was basically saying that if you shake the light back and forth the flickering becomes visible because you are spreading out the flicker in space. kinda like the Doppler effect in a sense

[@andrewaronson3364]

@@fayenotfaye it is changing the wavelength, but not by compressing or stretching like Doppler. instead it is spreading out the time domain into the spatial domain, enough to shift the frequency into the visible range

[@evilspoons]

My "favourite" situation is when I'm stuck behind a US-manufactured car that has *SEPARATE* red turn and brake signals. JUST MAKE THEM AMBER! There is no possible way to handwave this away as a cost thing because they already have the separate systems. As a bit of a "trainspotter" for cars I've built up the knowledge of most of these, which is a signal vs a brake, but the average person doesn't give a rat's arse and we need every possible tiny advantage we can get.

[@BrendonGreenNZL]

Amber would certainly be better, but that would require stocking a different part; and at least the two functions are clearly separated. We have a similar situation here in New Zealand; where the preferred colour is amber, but it is legal to use a red turn signal or combine it with a brake signal (which must be red). Consequently, I often see truck trailers with a line of red lamps across the top and three red lamps on each of the bottom corners. These are wired in such a way that the dim filaments of all the lamps perform the tail light function, the bright filaments of the outermost bottom lamps and the three outermost top lamps are dedicated turn signals, the bright filaments of the second and third outermost bottom lamps are turn signals overridden by the brake signal, and the central top lamps are dedicated brake signals. If you encounter this system for the first time, it can be a real mission to figure out the truck driver's intentions; especially if you are queued behind it and are not looking at the top-mounted lamps. I may have even seen one variation that uses a brake signal overridden by a turn signal for the second outermost bottom lamps; but I'm not too sure about that. °°°°°°°°°°°°° I'm a truck! I have more | | lights than you, and I'm | | going to use them all in | | the most confusing way °°°______°°° permitted by the law!

[@evilspoons]

@@BrendonGreenNZL I'm talking about a couple vehicles that have separate brake and turn lights, like the Infiniti QX50. I think the Infiniti uses amber, but there are other vehicles I can't remember that are red with red. They're obviously different parts and all they did to make the turns red was not use amber plastic. 😕 (A bunch of smaller crossovers from various brands jammed the turn signals into the bumper to comply with US laws that they're not allowed to be on moving bodywork, i.e. the hatch)

[@BrendonGreenNZL]

@@evilspoons Yep. It wouldn't cost any more to dye a plastic lens amber instead of red; just like it wouldn't cost significantly more to fit the aforementioned truck trailers with dedicated amber LED modules for the turn signals. The only advantage I can see of them being red is that the turn signals can be made more prominent when the truck is not also braking. As usual, though, style and form trumps safety and functionality.

[@bontrom8]

RIGHT. Until we are willing to employ all of the possible fixes, we are acting way too dependent on technological solutions which will be never quite good enough. Put another way, how many deaths will be caused in the name of progress, trying to make the perfect driving system? I really think driving itself as a skill performed by humans needs to be here to stay.

[@pauldzim]

Amber turn signals are ugly. I want my car to have red ones, safety be damned.

[@celticfan008]

The fact that you made that BMW joke with a straight face is some masterclass acting.

[@PhillipAmthor]

It not a joke im german and i see this every day, like literally! I always ask myself why the even got them when they never use it.

[@illyshaieb]

Who said he did one take?

[@HappySlappyFace]

i love your pfp

[@daos3300]

@uncletigger for a channel dedicated to explaining stuff, this was a perfect comment.

[@BertGrink]

Alec over on Technology Connections didn't mince words; he said it quite plainly: The combined stop- and turn- signals in the US ARE inferior to the European ones.

[@harriehausenman8623]

He makes some valid points. Very nice video indeed.

[@darkmann12]

i was just about to comment this!

[@Nilguiri]

The yanks love their primitive, outdated and dangerous infrastructure. The whole country is like that. It's like travelling back in time!

[@zenatsuryouichi]

@@Nilguiri So you're just going to ignore london, then?

[@Nilguiri]

​@@zenatsuryouichi Haha. Cool story. Nice try.

[@LiftPizzas]

LED tail lights visibly strobe and it's annoying as hell. Whenever I move my eyes I end up with 50 copies of those tail lights spattered across my vision.

[@erikziak1249]

I can confirm that. And I hate it. Especially when driving at night. Those flickering red lights are very annoying and disturbing. At least for me. The frequency should be mandatory at least in tens of kilohertz, ranging from 30 kHz to 40 kHz at least. Then I would not mind. And cameras would not mind either. As during each captured frame, the light would be clearly recorded.

[@tylergarza8695]

@@erikziak1249 'Strobing' at such a rate would basically negate the entire reason they do that to begin with. It's called PWM (Pulse Width Modulation), not "strobing". It's how a lot of circuits handle supplying a smaller overall voltage to a lamp, which can save on energy. The lower your rate, the more energy is saved during the off time. This lengthens the life of the diodes, and isn't particularly noticeable to the average person. You can see it if you move your eyes, yes, but the lights generally aren't bright enough to leave a lasting mark on your retina (like the sun does). So, dude, shut the fuck up. It's not hindering your existence

[@davisdiercks]

@Tyler jeeze mate calm down lol you're both right; PWM works by strobing so the terminology is same diff we all know what he meant.. And some people (myself included) have hyper photosensitivity or something where we see lights differently than most - I do a lot of Arduino projects with PWM LEDs and I always have to set the pulse duration much shorter than typical just to make it bearable to work with... I see it in cars, LED room lights, alarm clocks, microwave displays... Sometimes useful but usually just annoying so I agree with Lift Pizzas lol

[@tylergarza8695]

@@davisdiercks It doesn't work BY strobing. The strobing is a product of it's function. PWM is used in applications where lights aren't even involved in the first place. So no, it doesn't work "by strobing"

[@davisdiercks]

@@tylergarza8695 oh my gosh is this seriously worth arguing over 😂 Oxford definition of "strobe: verb. flash intermittently" So no obviously PWM itself is not strobing, as it could be applied to anything like motors, speakers, transistors, etc, but in this specific application the PWM causes the LED by definition to strobe. Also to my original point: calm down we're all just chilling here there's enough crap going on as it is without people like you seeking destructive attention

[@rainbowwarrior6452]

Technology Connections on turn signals: kzbin.info/www/bejne/hWLPi2ykZ8erjaM

[@gokulinath8508]

4:27 Yep we all know that BMW drivers never do that 😏

[@ChristianPaulDelage]

I've counted 3 burns so slick I fell on my ass laughing! Seriously, keep them coming! 🤣

[@dronillon2578]

Please, what "burns" mean in this context? Is it like joke/insult? English is not my first language.

[@ChristianPaulDelage]

@@dronillon2578 yes

[@JNCressey]

@@dronillon2578, burn is an insult in this context. examples from the video: - BMW drivers not indicating - users having problems with (presumably apple) phones and moving to android

[@davidbergmann8948]

@@dronillon2578 yes yes 🍄🍄

[@JNCressey]

@@wifixmash3r, Lets ask Steve what he was referring to. shouts* Hey Steve, what were you referring to?

[@bit2shift]

A solid argument against PWM in LED automotive lighting.

[@iamcurious9541]

What is your proposed alternative? You can't reduce the current because of threshold voltage. If you dimm the current the different colors inside the white LEDs would dimm unevenly and you would get green front lights. Unless you control the different colors individually, which would be way more expensive as you would not only need a more complex dimmer but also LEDs where every color CAN be controlled individually.

[@bit2shift]

@@iamcurious9541 alternative? use LEDs with different power levels for each task, just like it was done with incandescent/halogen bulbs: tail light→low-power LEDs, brake light→high-power LEDs

[@gianluca.g]

An alternative could be a random shutter opening. On average it would pick up the intended led brightness, it would not over expose the camera sensor and it wont sync up with any pulse modulated light source

[@dbmail545]

"A BMW driver would never neglect to use the turn signal" That made my day!

[@PankekoTheDragon]

"I'm not saying the turn signal in UK is better than US, I'm just heavily implying" LMAO

[@danieldaniels7571]

Ed Pankeko he’s not wrong

[@UltraGamma25]

The drivers in the U.S. are narcissistic idiots.

[@pauldzim]

@@UltraGamma25 The drivers in the U.K. all have bad teeth

[@UltraGamma25]

@@pauldzim I don't live in the U.K. so I don't know.

[@Abdega]

@@UltraGamma25 Tell me where they are *NOT* narcissistic idiots, because I want to move there

[@garyha2650]

10:32 The first 98% of building something is the easy part, true, it's that last 2% of perfecting that takes monumental effort and a whole different way of thinking.

[@Friendly911]

I never thought about this issue, thank you for bringing this to my attention, amazing video as always Steve.

[@theCodyReeder]

Your average Toyota Corolla uses over 100,000 watts to cruse at highway speed. I doubt incandescent bulbs are going to change the efficiency calculation much.

[@SteveMould]

You make a good point! Actually the main thing is reliability I think.

[@VaitkusMantas]

Do you mean the average Corolla uses over 100kW of energy in the form of fuel? If the average car would need 100kW output at the wheels to just cruse at highway speed, there would be a lot of cars which could not even reach that speed then. So let's say a car has two H4 headlights which use 110 watts of electric energy. Because of the average efficiency of an automotive alternator (70%) and a gasoline engine (30%) you need about 500 watts worth of gasoline. That is about 50ml of gasoline used just for the headlights for one hour.

[@edwardpaulsen1074]

@Cody'sLab While your calculations for total energy usage are generally correct, the application is not... most of that wattage was likely converted directly from horsepower which is a mechanical form of energy used to physically move the car along... (not including losses to heat and friction) the electrical power generation takes a fraction of that mechanical energy and converts it to electrical and yes, efficiency in the electrical system means less power taken away from making the car move. especially since Mantas Vaitkus pointed out the further losses in efficiency above. Just something to consider..

[@michaelmoorrees3585]

Though I love incandescent bulbs & Cody's channel, the switch to LEDs is probably more due to manufacturing, not energy efficiency. Yes, LEDs use a lot less power for light output, but its semiconductor production costs, and the economy of scale, that now favors LEDs. And its ultimately the $$$ that car makers are looking at. I'm a big color organ freak, and incandescent output vs input power are friendlier to deal with, with incandescents. An incandescent at 10% max power, will barely glow, while an LED at 10% (of its own max rating) will still be pretty bright to the human eye. For pure illumination, that's not an issue, but in color organs, and other dimming applications, it can be a real pain ! Plus a barely glowing incandescent filament is a thing of beauty, where a barely lit LED is just .. eh.

[@JayPixx]

@@michaelmoorrees3585 couldn't agree more :) I'm color organ freak too!

[@samuelprice538]

Love the awesome hidden gags. Wish they'd mandate high Hz for LEDs, personally I find the visual effects quite distracting, in particular my peripheral vision and when moving my eyes to and fro.

[@EggBastion]

Seconded.

[@beargun42]

Volvo’s are the worst. Very distracting when I’m driving.

[@mass1s]

Or they could keep the LEDs continuously on and control the brightness by varying the current. It's just slightly more expensive but so much nicer to look at.

[@Microwave_Dave]

Thirded.

[@olmostgudinaf8100]

Fourthed. My spouse thinks I am mad because I can see cars' lights flickering.

[@karatefylla]

"a bmw driver would never do that" haha I see this problem is universal xD

[@bastienmamdy505]

Once more, great episode! I work in image sensors development and we are already adressing this issue by developping high dynamic range flicker immune sensors.

[@drmkiwi]

Good stuff, thanks. It always fascinates and amazes me how people continually come up with such creativity in solving problems. Solving puzzles (problems) can be fun, and I guess often we classify somebody who enjoys solving tough problems a nerd. What a compliment! Cheers, David

[@FridgidIdgit]

Here's and idea for a potential solution. Have the "AI" use multiple sensors with several different framerates to decide whether or not a light is on

[@JohnnyDoeDoeDoe]

You guys watched to the end of the video right?

[@JohnnyDoeDoeDoe]

@@bosstowndynamics5488 Yep, I think that makes sense The OP's idea would be prone to a similar issue though

[@Anankin12]

Or, you know, just use colour coded lights for different signals. Like amber for turning and red for braking.

[@ganondorf5573]

@@Anankin12 This also requires changing the environment and making sure all cars do that.

[@4umata]

@@bosstowndynamics5488 how hard would it be to make the cameras just detect the actual event of the object decelerating/stopping? you read my mind with the 2 camera solution there

[@AageV]

10:14 - Gamers. 10:17 - Game developers.

[@JNCressey]

//don't delete this tomato. I don't know why but removing it causes the level to break.

[@MrSaemichlaus]

I love the intermittent roastings, and you did a brilliant job with using footage to explain things! This was like a polish course to all the little shower thoughts I've had on the topic :)

[@lladerat]

I always had intuitive understanding of why some lights appears to 'flow' from on and off and why helicopter rotor blades looks so weird on videos, i knew it was about the framerate not aligning with the lights frequency, but i would never be able to explain it properly, you did it perfectly man. Also great bmw burn, that is some Jeremy Clarkson level of burn.

[@RudyOMP]

4:29 “A BMW driver would never do that” 💀💀💀

[@mattc3738]

Whenever I am presented with a engineering problem, I ask myself "is this problem really the ONE thing humanity will never be able to solve?" and the answer is always "probably not"

[@benlawton5420]

There is a solution but car manufacturers are greedy.

[@phazonlord0098]

Pretty much the same reason the US stuck with those god awful red turn signal. I mean they're not really a problem... most of the time.

[@behavedave]

Fundamentally problems are rarely solved, they're mitigated.

[@drdca8263]

This seems to rely on the assumption that there is exactly one such problem, and I don’t see a reason to assume that?

[@Hallowed_Ground]

@@drdca8263 Actually, it seems to rely on the assumption that humans solve all problems, or at least very very rarely fail to solve a problem, which is simply not true. In fact, problems are scarcely solved at all.

[@mulhatton]

WONDERFUL... thank you for addressing this. This is one of the most relevant and informative videos that I have seen in weeks!

[@byronwatkins2565]

"Extraordinary claims require extraordinary evidence." Knowing as I do how poorly computers respond to unexpected events, I am not optimistic regarding self-driving automobiles without first eliminating most of the chaos from road traffic.

[@bspringer]

"a handful of people" Louis Rossmann incoming 😂😂😂 I laughed so hard Many great little implications there ;)

[@mikeuk1927]

Bastian Springer Only a very small percentage of people will understand what you are talking about.

[@bspringer]

@@mikeuk1927 😂👍🏻

[@EggBastion]

???

[@bspringer]

@@EggBastion you're seemingly not one of them

[@dan_]

@@EggBastion Apple make bad phones and crap software, is basically the point.

[@zvpunry1971]

The mirrors of my motorcycle sometimes vibrate a bit. If they vibrate, everything becomes a blur. But some of those LED lights become a swarm of bright dots flying around. ;)

[@harriehausenman8623]

My exact same experience, except for the motorcyle part: It also happens on cars with a slightly shaky/vibrating centre mirror.

[@iamdave84]

Same issue with my AMOLED phone at night when driving on a bumpy road. The screen strobes to lower the perceived brightness and text becomes unreadable.

[@scottsieke7948]

What's a "commute?" I know I've heard that word before, but it's been weeks...

[@somefuckstolemynick]

N L r/woooosh

[@hotflashfoto]

Moving your coffee cup from the kitchen counter to your computer workstation... :D

[@paxundpeace9970]

Current problems

[@buddyclem7328]

Your commute is the trip you take to, and from your work.

[@Gwalchgwyn]

@@buddyclem7328 : Did you duck, or was that one just flying too high?

[@lostboytnt1]

I was eating when watching this, and I almost spit out my food laughing, when you said "a bmw driver would never do that' about not using the turn signal.

[@Unleashed75]

The BMW joke really tickled me because it is true. Having been a BMW at one point in my life I would of been annoyed with this because i always use my turn signal but honestly taxi and BMW are the worst I've seen for not using them. Being a class 2 truck driver and a superbike rider, I've seen it first hand. As for having Red turn signals, wow. Just how stupid do you have to be to design that. I never knew this was a thing.

[@elmo2you]

I felt a bit bad adding a like while it was at 555, considering that the NE555 chip is the historical go-to IC for generating periodical on-off signals (incl. blinking lights and PWM dimming).

[@harriehausenman8623]

Top nerdiness level reached.

[@4ntig3n]

Hey Steve, you know - I loved the video and it's main content. But it was when you showed Merck the sponsor, and especially their world of curiosity, when you got to me. I was always confused why others around me don't "see" the world as I do and don't even try to understand how things work. I guess that I'm just a curious person and thought that everyone else was too. Thanks for the great video :)

[@BritishBeachcomber]

4:22 In my experience, BMW drivers appear to be exempt from using turn signals. Everyone knows that they have right of way.

[@rickseiden1]

I'm particularly sensitive to this. My eyes naturally dart just slightly back and forth as I watch the road ahead. This ends up leaving ghost images of the brake lights in front of me when they are LED lights. Cadillac SUVs are particularly bad for me. I'll see two or three ghosts of the real break light on each side of the car.

[@betabenja]

"Milud, the defendant says that he has had no issues driving and that he has a clean driving history. But I present to you this online post posted by him on the 3rd on March this year in the comments section of a popular video sharing website, KZbin. In this post he clearly states he is at a reduced driving capacity due to poor vision. Mr. Seiden, do you deny that this is you that has posted this comment?"

[@RandomNullpointer]

Yes in deed, it is very annoying, and I hate it. Manufacturers should use much higher frequency for the PWM generator.

[@matthewseymour8972]

Volvo particularly bad I find.

[@rickseiden1]

@Troll King Edited

[@rickseiden1]

@@betabenja Alternatively, "On April 2, 2020, Mr. Seiden posted a comment about his problems with the brake lights of Cadillac SUVs, and numerous other people replied indicating they have similar problems with this issue as well. Your Honor, we'd like to make this lawsuit a class-action suit, and increase our request for damages to $250,000,000."

[@Poolie]

They really need to create a standard for this

[@gemmerslemon895]

Yes and standard cars for everyone in the world, so no more problems like this will happen. It's radical, but it can saves lives.

[@threeMetreJim]

That would be ideal but then you'd have people installing cheap lights from China (assuming things go back to how they were not long ago) and having, or causing, accidents.

[@JohnJackson66]

It's nice to see a real problem and proposed solution. I did wonder whether they might increase the frame rate as well, to counteract the motion blur issue.

[@halonothing1]

I just got some PWM controller chips a couple of weeks ago. This video's making me want to experiment with different frequencies, duty cycles and phase differences between the PWM signal controlling an LED and film it with a camera. Preferably one whose shutter speed I can control. It gives me a good excuse to learn to use these controllers and to actually use them instead of just letting them sit around until I need them for something. Which is usually what happens to most chips I buy.

[@adamwishneusky]

I wonder if they've tried having multiple cameras with different parameters eg frame rate, and have software try to figure out reality based on those several inputs 🤔

[@cheeseburger118]

That's exactly the idea I had while watching the video! Surely 2 cameras with slightly different frame rates could be compared to determine really quickly and easily what the light is actually doing.

[@teddyruxpin3811]

But then you are left with trying to analyze two different videos of the same object. Which one do you believe?

[@zing-rsa]

@@teddyruxpin3811 You don't use either. You use the knowledge gained from both and combine it to decide a most likely scenario. Or if you could find a combination of parameters that allow you to theoretically rule out all other possibilities, then you are able to settle on one.

[@Bob5mith]

You could also use multiple sample rates on one camera if the sensor had a wide enough sensitivity range and throughput to "see" all pixels at once.

[@alazrabed]

I've heard Tesla's doing something like that. They have two chips on board, linked with their own power supply and fed by their own set of cameras. In the end their conclusions are compared. I'm unsure what happens when they drastically differ though.

[@EmissaryOfSmeagol]

This is a really cool look at a neat engineering problem

[@EezyPeezy55]

Love your videos! Keep them coming :-)

[@_Piers_]

Important LED lights shouldn't be PWM, they should be current limited. It's easy to do and costs an inconsequential amount. That'd solve all the problems.

[@ahmadhackett7383]

Oh my gosh bro you just made me understand something. Ok so I've been working on my car for a few days now and I have a problem with a solenoid that controls fluid pressure inside the transmission. I've been using a standard multimeter to test the connection between the ECU and the connector I've been getting 12v for each connector in the series that leads to this solenoid. I've been on a coupe car forums asking questions and one guy said I need an rms capable meter because the solenoid uses a PWM VOLTAGE which was complete gibberish to me until this video along with your comment just helped me out a lot thank you Piers

[@Tomixworks]

There is nothing wrong with the PWM, the problem is cost cutting. All these manufacturers are ignoring the output filter between the PWM driver and the LED to save a few cents. Some theory around this: www.allaboutcircuits.com/technical-articles/low-pass-filter-a-pwm-signal-into-an-analog-voltage/

[@stargazer7644]

Lights are PWM because heat becomes a serious problem when operating devices in the linear region. Mosfet transistors have very little resistance when full on, so they don't dissipate much heat even when controlling large currents. If you were to bias it on at 50%, you'd melt the mosfet. Maybe what you need to do is put a low pass filter after the mosfet to smooth out the PWM to a lower average voltage.

[@communitycollegegenius9684]

@@stargazer7644 right. And LEDs have a very limited range of current limiting. They are not resistive, they are diodes. And even samples all in the same lot, they dim at very different currents. PWM is the only solution to LEDs. btw you would use bipolar for current limiting, not mosfets. We only filter to limit spurious emissions. You CAN hybridize current/pwm, but NOT on a diode. The most reasonable solution is to just increase the frequency to beyond what anybody would use on cameras -- 50K. Make it a law!

[@PaulMansfield]

or require multi-phase multi-bank LED arrays so that there's no visible flicker?

[@MattSieker]

I notice this all the time. The car I drive has a camera on the right rear view mirror that turns on and is displayed on the center console when the right signal is on. There are so many cars that PWM their running and tail lights. Probably some combination of faster shutter speeds, and faster PWM is the way to go. Though if you go too fast with PWM you start getting into the audible range, and there's so many components that emit found once you're in that range.

[@Ultrazaubererger]

Just go over the audible range. LEDs can be driven with 100khz PWM no problem. But why not ditch the PWM entirely? There is no need to vary the Brightness of the Lights (If you want cool effects you can still have the maximum brightness be full on, no PWM).

[@superdau]

@@Ultrazaubererger Higher switching frequencies require more specialized components to reduce losses. The transition from off to on and on to off is where most of the losses come from. So you want as few of these transitions as possible, especially when driving a whole array of high power LEDs. If you don't vary the brightness then how do you differentiate between tail lights and brake lights?

[@Ultrazaubererger]

@@superdau True but 100KHZ is not that high, I guess it would not be a problem at all. Might cost 0,1$ extra. "differentiate between tail lights and brake lights" Just make two lights like it was before with incandescent. Yes, even more cost, but cars are fucking expensive so it shouldn't matter. Also this is a matter of safety.* An extra 100$ or even 1000$ should not matter. *Flickering lights can be very distracting in your peripheral vision, I often confuse them for emergency vehicles and almost start braking before I notice its just a normal car. This might loose me the second I need to see a child run onto the street or whatever.

[@Richardincancale]

Interesting - a possible solution is just to have multiple cameras / sensors, in the same way that many phone have 2 or 3 cameras. One camera can have the low ISO / shutter 100% open mode for detecting lights, traffic signs etc., and the other with short shutter speed to avoid motion blur for detecting moving objects / road side etc.

[@PhillipAmthor]

Ok we could standerdize framerates in car LEDs and don need to put even more expendive tech in it

[@gourabghosh398]

Steve your contents are very interesting. You deserve much more subs sir. Love from India

[@alexczar1456]

Inspiring video and good info. Thanks

[@flotro9684]

"... but a BMW driver would never do that" *laughs in german Autobahn*

[@RICDirector]

WOW!!! Thank you, Steve!! Knew I hated those things for a reason.

[@harriehausenman8623]

A lot of those systems acutally flicker in my peripheral vision. It is super annoying.

[@maclman38]

Great video, never knew you could dim an LED in that way!

[@omzarinio]

Great video, thanks Steve! Made me wonder about dash-cams and footage being reviewed after an accident; I’m sure people have been wrongly convicted of reckless driving for “not indicating,” when in reality it’s the camera’s fault.

[@nokanol45]

Video idea: why does heat shrink shrink?

[@pdroa6666]

its because of the heat

[@JNCressey]

It's made out of socks and favourite jumpers.

[@Yrouel86]

The short version is that the tube is heated up while being stretched and then cooled in that stretched position, when you heat it back up it shrinks back to the original diameter

[@Miaumiau3333]

Actually, shrinking the heat shrink doesn't provide enough evidence. Heat shrink is the process of storing a low-temperature compound as a high-temperature solution in a highly porous structure (called a porous membrane). To see how this works, take a baseball bat and light the end on fire.

[@threeMetreJim]

Maybe it doesn't shrink, and just loses it's stretch instead. Like a soft drinks bottle made from PET.

[@frollard]

One would imagine that the self-driving computer engineers have taken stroboscopic response and calibration into mind.

[@sagacious03]

Neat video. Thanks for uploading!

[@rjmun580]

In the 1950s we had cars with semaphore arm indicators and box brownie cameras. We had no problems with flicker in those days but sometimes the indicator would stick and you had to lean across the passenger and give the door pillar a good thump to release it. There's always been problems with technology!

[@enoughofyourkoicarp]

Meanwhile: Elon: "Make it drive it's self." Engineers: "Oh god, ok, let's have a look, see what we can do." Elon: "I want to hit it with a sledge hammer." Engineers: "... Fine." Elon: "Now make it fly." Engineers: "Has this guy seen the 'god makes things' reddit or something, ok, self-flying cars, sure." Elon: "Will it go to Mars?" Engineers: "... Depends how much you're paying me." The engineers really are the heroes here.

[@trabladorr]

That's quite an interesting problem! Cool video! It makes me wonder, how would the motion blur from having the shutter open for 100% of the frame time affect image recognition? At highway speeds (~120 km/h) and standard framerate (~30 fps), the camera would move ~1 meter within the same frame. That would make for significant motion blurring within each frame! Can it still read road signs in this scenario?

[@clarencelam1907]

I would imagine that you could have one camera using a longer shutter speed to read turn signals, etc. while another camera is used to read road signs.

[@jacobharvy]

"You could just ignore it because its only effecting a handful of ppl and they'll just jump ship to Android" that got my like this time Steve. Also, I like the subtle comedy throughout the video, do that more often.

[@OliCambrayPhotography]

I wondered about this a while back and similar issues about driverless cars "talking " to each other. I wondered about if they had a local WiFi signal, like drones have for their control module, so they could talk to each other, like drones often use for their control, rather than relying souly on visual cues. The obvious issue with that is it would take quite a long time to phase out cars that didn't have this system built in.

[@docwhogr]

flickering led lights isn't only problem on cameras, is very annoying on my eyes too, especially when you move your eyes.. pwm should be banned.

[@IAdryan]

My TV regulate brightness with PWM. At low brightness i see multiple images when i look around the screen. Especially on subtitles, it's like stairs of text everywhere. Backlight should be solid light !

[@TonyLambregts]

Amber for directtion indication, Red for stop is a better system. No ambiguity.

[@TheOwenMajor]

Or you could use the most basic of common sense. I here your comment repeatedly, it is such hand-holding dribble. If you can't tell the difference between a flashing red light and a bright steady light then you shouldn't be driving period. There isn't any ambiguity. Red bright steady light = brake, Red flashing light = turn.

[@TheOwenMajor]

In my view you should be paying attention to the actions of other cars, not their indications. While indications can be helpful they should never be relied on. Think of firearms, safety are useful, but should never be relied on. When I took my license test I forgot to engage the safety, but only 1% was deducted because it should never be trusted.

[@TonyLambregts]

@@TheOwenMajor you do realize that the amber is in addition to the flashing right? Do you have objections to seatbelts, antilock brakes and airbags as well?

[@Lampe2020]

You could mandate voltage-based brightness control for safety-critical lights or at least e.g. a capacitor that takes the PWM signal and gets charged-discharged-charged-discharged-... by it and thus provides a semi-stable lower-voltage signal to the LED. Or just make the PWM frequency in the kHz range to prevent the effect described in the video plus the dotting of the light smear when moving your eyes, which many other commenters complained about.

[@user-it6gl1vv7v]

thank you, steve! Very cool

[@lluic]

Steve "Innuendo" Mould

[@andrewradford3953]

Is that an Italian suppository?

[@andrewwmitchell]

"I'm just heavily implying it." Hahhahhahaha

[@Krystalchan2009]

1:30 while this is true they can use the same lights to turn or brake, but there is a catch to this that I don't think the UK has since they have separate turn signal colour. The US has whats known as the 3rd break light law or the Center High Mount Stop Lamp (CHMSL) law where cars here are supposed to have a 3rd light in the middle to signal stops. But this could have issues with imports but you might get pulled over for lacking it. So in the US you can try and look for the section of a car where you expect to see a 3rd breaklight and even though its red like turns, the position would tell the system. Speaking of imports and cars that have it installed as an attachment, the position could vary and might not be easy for the sensor to pick up for one reason or another (like the lights arnt the correct frequency so the car thinks its something in the ambiance)

[@matthewtalbot-paine7977]

A solution I thought of like 15 years ago, not for this problem but for cars in general is to have them all communicate. Instead of having the cars read the turn signals they just receive information wirelessly telling them what a car is doing and that car can be identified by it's number plate. You could also use this communication to tell other cars where traffic is so that they can avoid it. Realistically this communication can only happen between driverless cars but eventually it will become so safe to drive an automated car that they will ban you from driving a car yourself.

[@keco185]

Don’t many cameras have automatic anti-flicker systems?

[@roseroserose588]

As far as I'm aware, those are for mains AC frequency (ie 50/60hz depending where you are), and work by syncing up the shutter speed of the camera with the appropriate frequency. Much harder to do that when the frequency is totally arbitrary and could change at any moment, e.g. a gentle fade in/fade out with an LED which is actually a series of pwm frequencies

[@keco185]

Edward Hobbs i wonder if similar algorithms to that used with autofocus could be used to calculate the amount of “flicker” seen in an image and just adjust the camera frame rate accordingly. Try a couple nearby frame rates -> get the gradient for the amount of flicker between those frequencies -> then perform gradient descent to determine the optimal frame rate to reduce flicker

[@brantwedel]

Those are targeted towards A/C powerline electrical frequency flickering 50/60hz. LED's have variable frequency PWM depending on the LED controller.

[@bspringer]

As others have pointed out, this done by syncing the shutter speed and/or framerate and therefore it can only be done for the AC grid I'll give one more reason: even if there were more than these two options, what would it help if you're trying to monitor multiple cars simultaneously? You would need different speeds for different parts of the image...

[@keco185]

How hard is it to increase the PWM frequency? You can get well into the kHz very cheaply. Or at the very least have a smoothing capacitor

[@Anankin12]

Ain't capacitors stupidly fragile?

[@rgbii2]

Problem is that there are already a lot of these cars on the road, so even if you made this change to new cars, AI/self driving cars would still have to deal with the problem for years to come.

[@keco185]

rgbii this isn’t really a suggestion for a fix. It’s more of a question of why this was never done as it doesn’t really increase the cost and makes the car more photogenic

[@youkofoxy]

@@Anankin12 depends on the capacitor tech. But you can also use inductors. And they are very resilient.

[@DantevanGemert]

What is the need to dim the lights anyway? You want the brightest lights, why would you want to dim them?

[@jpsimas2]

this is a nice and practical example of signals being sampled wrong and of how Nyquist theorem affects life. the light signals have a bandwidth larger than the sampling frequency and therefore you get frequency rollover when sampling and therefore get those weird effects on the sampled signal

[@Peter_1986]

The trickiest part about building self-driving cars is probably to construct them so that they can interact with _each other_ in dangerous situations and quickly come to a mutual decision on how to react to that situation. It probably involves something like finding the greatest average distance from all other objects - kinda like equally charged magnets.

[@catradar]

How do car cameras deal with sudden large changes of brightness like driving into or out of a tunnel?

[@17hmr243]

blinkers on the inside of the head lights next to the middle of the car should be illegal blinkers should be on the out side of the head light so u can see them wile they start to turn.

[@hebl47]

I'd also make it mandatory to have an extra pair on the side mirrors. Those really improve visibility.

[@robertszynal4745]

You managed to find another of the differences between US and EU regulations. In the EU you have to have side indicators but in the US you only need them at the front and back.

[@98dizzard]

In the EU, where daytime running lights may interfere with indicators (i.e in the same lamp unit) the daytime running lamp turns off while the indicator operates. At night the issue is much less of a problem.

[@tin2001]

@@hebl47 Except everyone stopped putting the side door/fender lights on when the mirror lights became cool.... Which means you can't see them from behind the car. There's literally 3/4 of the car length that's an indicator blind spot. Bizarre how we allow that one.

[@hebl47]

@@tin2001 And who said you'd ONLY put them there? It's just one additional spot.

[@Pieman93]

Yes, finally! Ever since the new purple (mauve?) end screen appeared I've been waiting for any kind of little 'easter egg' to appear through the light bulb window in the bottom corner. And finally, we get ... a little bit of Steve's hand. It's not much, but I'll take it.

[@IbakonFerba]

Sponsored by Merck? This is the first video sponsored by them I've ever seen, my dad works there, gotta like this ;)

[@purplefire2834]

Steve's the first person I've heard who says "iso" instead of "i s o" and I'm suddenly wondering if I've been saying it wrong

[@nofunsir]

This has ALWAYS annoyed me. It is dangerous, as, even though the eye's "refresh" rate is about 40ms, that doesn't account for something sweeping across your retina, as when you are driving at night and looking around. It appears as there are multiple objects and your brain has to do more processing to predict movements -- highly dangerous! Auto Engineers really need to stop doing this and just put solid-on LEDs in all cars.

[@1951split]

It really annoys me too... I though I was the only one...

[@seasong7655]

We need the *FULL BRIDGE RECTIFIER™*

[@catsnorkel]

The eye's refresh rate isnt comparable to digital refresh rate at all.

[@nofunsir]

@@nugget6635 This is true, and why I put "refresh" in quotes. It is, however, true that for a given spot on your retina, a changing signal takes 40ms longer than for example, a changing sound, or a changing touch, to be registered by the brain. Setup a circuit that randomly flashes an LED and have a person react by hitting a button, and time the response. It will ALWAYS be slower than a sound-based reaction. This is due to physical limitations in the makeup of the retina rods and cones, and turning light into electrical impulses in the back of our eye.

[@nofunsir]

​@@catsnorkel That's why I put it in quotes, you goober. To the lay person it is very comparable. Generally speaking, you cannot see (brain included in this system) changes faster than x Hz, which is the whole reason why engineers modulate the LEDs, why TVs work, and how mp4s work on this very site you're on.

[@13thravenpurple94]

Great work 🥳 Thank you 💜

[@messiermitchell4901]

One solution might be to have two camera running at different frequencies, then compare and contrast. Also BMW drivers.

[@sgv6618]

6:49 @standupmaths Why is the Apple Calendar so broken?

[@medusasworldofstone]

Last time I was this early BMW drivers always used their turn signals..

[@lukav]

Hi. I've finished Udacity Self-driving Car Engineer course which covers all the basics of self-driving cars. When it comes to predicting other vehicles and object movements the lights ware actually not used in the projects we ware making. Many people are not using their lights and there is also the possibility of giving a wrong signal so this very unreliable measure. Prediction is made with mathematical models using the objects speed and direction and their change overtime. Using lights signals can assist the decision making process but it would have very low weight compared to the data from the other sensors. Processing time is also valuable since there are many things happening many times a second that the car have to compute, so if the lights are so unreliable it makes sense not to bother trying to detect them at all. There is of course the case of Ambulances and other special vehicles. Those can be initially detected by the shape of the vehicle with AI which is used for detecting the object anyway, so once such a vehicle is detected then you can spun a separate process to check the lights in order to determine if the vehicle is in special mode of operation and take appropriate actions. I'm just saying :) Thank you for all your great videos. And to all: Stay safe, stay home

[@BrendonGreenNZL]

Is there any possibility of a line of PWMed lamps being mistaken for small, slow-moving objects by virtue of the stroboscopic lighting? Think a long truck moving perpendicular to the camera with PWM-driven side outline markers.

[@lukav]

@@BrendonGreenNZL I would say very unlikely for several reasons: 1. The AI labeling objects is trained with datasets (pictures where the object is labeled as a hole) so it can learn for what features to look for as a hole not specifics. Think of it as a new born baby where you just give it a pictures of different vehicles and reward it only if it guess correctly. So over time it would get better and better. 2. Usually data from radar and/or lider is also taken into account, so this would provide some sort of additional filtering. Although I think Ilon Musk opinion is only camares are enough and make financial sense. He has a point but this is another discussion and it changes over time. 3. In order to filter outliers the algorithms usually have a degree of trust in the detections. That is if one object is present in one image but is missing on the next two it would probably have vary low certainty number and would get ignored/filtered. That it what comes to mind at the moment, but even if all of those failed you still have to thing would that false detection be a problem and even more importantly a hazard. If you have a false datection of a moving object it would only be a hazard if you are moving with high speed and the action you take on that detection endangers your or someone else vehicle. You should know that the decision tree algorithms take in to account much more that you would expect and even more that a human. The sensors in the car gives you a very precise information for all object in your near 360 degree surrounding area and even further than that. More importantly you have the speed of each object, the change in speed and the rate of change of speed, which gives great advantage in predicting where all the objects will be in the near feature. That is something that you as a human cannot do since your vision and focus is limited. So I would say even if the car falsely detect an object that is not there and decides to reduce speed for example, it would most probably just cause some discomfort for the passenger but not a hazard. Sorry for the late ng comment, but it is a complicated matter for a long discussion :)

[@Legominder]

2:35 that differs though when you move your eyes. 1000 Hz is visible on your retina when your eyes (not your head) move from one spot to another moving very fast. Then you notice whether the blurred light lines are dotted. Especially with high contrasts. Not only the light source itself, also at e.g. reflections/sharp light edges. Also applies for screens. That's why e.g. EIZO monitors try to dim through voltage in the range possible Advanced PWMs use a broad random frequency spectrum, so PWM without any periodicity. Thus the brightness will appear about normal (just noisy) for any framerate, shutter angle and also blurred lines have no regular periodicity. However, wherever possible, fine voltage control monitoring the actual current (the determing property of diods regarding light output...requires super accurate current measurements with lights having huge dynamic ranges: dimming to exactly 0,100% of the maximum current) are just nicer.

[@betabenja]

4:30 A man after my own heart

[@eskohc984]

you earn like for that BMW joke xD

[@1FatLittleMonkey]

This effect could be used to our advantage for self-driving cars by making other cars _more_ visible to camera sensors against the background of other lights/glare/reflections/dappled-light/rain/etc if the blink-rate is made to be distinctive. If auto-makers who are making self-driving cars (which is nearly every major brand) created a standard for the blink-rate of different lights, matched to the sensors' scan-rate or frame-rate, then car lights would be screaming to each other "I am a car, I am a car". Moreso, it would give orientation information, "This is the back of the car", "this is the front". "this is the front as viewed from the left hand quarter", making the job of identification and tracking easier for other AIs. Going further, they could also use the blink system to pass information to each other about their status and intention that doesn't require RF signals that could interfere or jam. With lights, you have to have line-of-sight, which means you are sending only to the cars that can see you, which is what you mainly want. Emergency vehicles could have the same thing via their roof lights, visible over a longer distance to more vehicles. Traffic lights could include timing info, even traffic data. (And cars could signal to traffic lights to allow traffic systems to "know" where cars are headed, to adjust timing better. Including "I'm a car on autopilot, feel free to assume better-than-human reaction times, but shitty pattern recognition.") (By "Status", I mean things like "rate of braking/acceleration". Normal brake lights are a binary, you either are or aren't. We rely on human pattern-recognition/motion-perception to fill in the rest. It would improve car-AI drastically if the cars were telling each other, "I'm at speed" vs "I'm decelerating but not braking yet" vs "I'm braking normally" vs "I'm braking as hard as possible because emergency!". Showing "Intention" is to similarly extend the range of info beyond turn-signals' yes/no. "I'm going straight across the intersection, but then immediately turning into the carpark on the other side".) And then one day, Steve (or Alec or Joe or Tom) could do a video on "the secret world of car signalling".

[@christiansrensen3810]

So right. But also analog sign readings. My car sometimes pick 5 km/h limit when I am driving on the highway. So regulations on signs an placeing .

[@caiocc12]

This is manufacturers being cheap and using cheap'o LED drivers that do PWM dimming instead of a proper current limiting circuit. They are saving a few dollars which is unjustifiable in car manufacturing or traffic lighting. Just greed

[@MisakaMikotoDesu]

The problem is that these lights are already out in the wild. Even if you made manufacturers pay for replacing the lights, you can't enforce it because police wouldn't be able to see the flicker, and many people simply wouldn't bring their car in for what they consider a "minor issue".

[@zappergames4785]

For real. The unregulated LED headight market is awful, it gives a bad name to LEDs and legitimate technology. They should use linear or properly regulated drivers rather than resorting to PWM.

[@daviXD18]

Pwm can be easily filtered, maintaining effeciency with same result as a linear regulator

[@1boobtube]

@@daviXD18 indeed. Kinda scary the op thought process lol.

[@aw3man_]

This is why it's not gonna work: The End.

[@WillWill56]

I'm surprised nothing was mentioned about ND filters, quite popular on GoPro cameras for mitigating almost the exact same problem. Basically putting window tint in front of the camera lens, allowing it to have a longer shutter time without over exposing, although it would reduce the camera's night vision so you might need some way of mechanically or electrically removing or switching off the ND filter at night. Just having adjustable sensitivity/ISO setting in the camera itself might be the easier option anyway.

[@charlestaylor3195]

Back east where they get substantial snow in winter, a county changed all their traffic lights to LED to save money. Winter comes and snow covers the traffic lights so they're not visible. The county had to send workers out to physically remove the snow at great expense. They realized that the old incandescent generated enough heat to melt the snow and the LEDs were too cool. The county returned to the incandescent because it was cheaper and safer in the long run.

[@sooocheesy]

4:23 Part 2 of this video will be how BMW drivers confuse self-driving cars.

[@Tinker001]

BMW drivers confuse people driving cars...

[@sugarshock7925]

Ah, I know this! It's the Nyquist Shannon Sampling Theorem!

[@dr_arcula]

Kindly elaborate

[@williamson39]

What if we required vehicle and traffic led lights to have their arrays ganged into distributed ("overlapping") subgroups so that their net effect was still the desired consistent brightness, but some were always on? That is, distribute the duty cycle to mask the off phase over the entire area of the light, rather than just all or none at once. Few if any are single diodes, so put every second diode in the array on a gate.

[@esbrasill]

@11:10 I have started so many project unhindered by any knowledge, and in the process thus learned a lot