- Hey, it's me, Destin.
Welcome back to Smarter Every Day.
This is my buddy Chad.
- Hey.
- We are absolutely giddy because we've been working
on something for how long?
- 12 years.
- Well, I'll be like that's us hanging out
but we're working on this project for how long?
- I don't know, a good four months.
- Four months.
Chad's really good at software and we had an idea
and so there's a patent pending product
that we're working on.
What it does is it eliminates kickback from handsaws.
Chad, do you wanna explain what's going on here.
- Yeah, so you'll be cutting a piece of big
a big sheet of plywood and as you get down towards
the middle of it the pieces that you've already cut
start to bend towards each other and they'll pinch
the blade and when the blade gets pinched it becomes
kind of a wheel and these teeth, since they're coming
back towards you, catch in the wood and then the whole
saw comes back at you.
- It's a big deal.
If you've ever had it happen, maybe a couple drops
of pee came out.
- Terrifying.
- You know exactly what I'm talking about.
We're gonna show how it works first with the high speed
camera and then we'll show you the fix we have
for kickback.
- [Chad] Turning it on, three, two, one.
(motor rumbling)
It wants to go.
- [Destin] It wants to go?
I'm ready.
- Three, two, one.
- [Destin] Whoa, it's still on, kill it.
What are we doing?
- [Chad] And it came out 'cause it got to the knot.
- You notice we have this chain and we've got
this danger radius there.
Will you show and make sure that the chains
not gonna hit the, yeah.
(motor revving)
(gentle music)
- Oh, yeah.
- You need something for these safety glasses.
Because of the rotation direction of the blade,
the saw is lifted up out of the workpiece and then
that rotation, again, causes it to be propelled
towards the user.
Now obviously, if this were to really happen
you would want to release the trigger on the saw
and in this test we have it zip tied so we can actually
see what's happening but I found, personally,
that my body tenses up when I get startled
and I'm not so sure that I would have enough control
in the moment to make the decision to release the trigger.
Let's look at another run and I'll stand just outside
the danger zone and I'll pull focus on the camera lens
and we'll see if we can measure the human response times
required to avoid injury.
Whoa.
- That's scary.
- [Destin] Okay, in this run, look at the timer in the top
right of the screen that's counting from the moment
the saw starts rising up out of the wood.
You can see that the blade is fully released
from the wood within 80 milliseconds
and it's already headed up towards your gonadular region.
Assuming that you don't tense up, you would need
to respond by releasing the trigger well within
a tenth of a second.
Once the blade is freed from the wood, there's no longer
any resistance and therefore the blade increases speed
because the motor is adding angular
momentum to the system.
Now that makes it even more dangerous and you can see
here when the blade falls back down and comes back
in contact with the wood, just imagine if that was flesh
and keep in mind here that this is a slow-mo video.
All of this that you're seeing here is happening
in just a tenth of a second after the blade
has lept up out of the wood.
Obviously the ideal time to respond to a kickback
event is before the saw even leaves the wood.
The problem with all this is often times humans
simply can't react that quickly.
That is no bueno.
It's a bad day, man.
Okay, so that's kickback.
It's very scary.
Now what we're gonna do is show you what we've made.
What would you call it?
It's a multi-axis detection system that can figure out
kickback based on machine learning.
- Keep going.
- [Destin] And basically dynamically break the motor.
- Yeah, so I can give you a demo
on the first one that I built.
So I'm gonna turn it on and let go with my finger
and you'll hear it turn off quickly.
See that?
- [Destin] Yeah.
- If there was no brake, it would just keep
it would keep spinning.
So I put a sensor in there to sense a kickback
so that when I do that
it shuts off automatically.
- [Destin] So your finger was still on the trigger
but you just accelerated it backwards.
- Right, this was the first one that I built
and since I just used an accelerometer
there are some false alarms
like if you bounce it around or just normal use
it can trigger and the new one that I did
I used a nine-axis accelerometer,
gyroscope and magnetometer.
So the really fancy thing that we're doing here
is we're doing a machine learning algorithm.
- [Destin] So you don't care.
- I'm not really programming in exactly
what the thresholds are that I need it to sense.
I'm taking data from dozens to hundreds of people
using a saw in normal, everyday ways
and feeding that information into a neural network
and I'm comparing,
stop grinning.
- We're cutting plywood here.
- So machine learning works by you take a big data set
of people using it in normal ways and then another
big data set of kickback events and the computer
automatically takes all those, all those data sets
and figures out what the anomalies are.
What's unique to kickback that's different from normal use.
- [Destin] So you hogged out the handle it looks like.
- [Chad] I did.
- [Destin] And so there is a legit computer in there.
It has accelerometers and gyros in it.
- [Chad] Yep.
- Three, two, one, go.
So it stopped itself?
- Yeah.
- It stopped itself.
That's what it does?
- That's what it does.
- That's awesome.
- [Chad] To better understand how the system works,
we've overlaid the data on top of the slow motion.
We're measuring nine different sensors here
but for simplicity's sake let's just look
at the overall magnitude of the acceleration
which is in yellow and the magnetic field
which is in red.
You can see that when the saw itself,
not the blade, but the saw itself starts to accelerate
the saw's braking system is applied and the magnetic
field starts to work against the rotation of the blade.
The cool thing about using magnetometers
is that the algorithm might be able to detect
the magnetic field from the motor and then make
decisions based on that information as well.
- [Destin] And so you just combined those different
things together and make it make a decision.
- Right, I just let it capture all that data.
I don't tell it what's important.
After the fact, if it's been a kickback, I annotate
the data with this was a kickback event
and then I have a whole bunch of other files
that are regular use cases and it figures out
what's important in the kickback event
to trigger output.
- [Destin] That's awesome dude.
- Yeah.
- [Destin] Three, two, one.
- Ooohh.
- It did stop, though.
- [Chad] So we performed all of those tests
by starting the saw while it was already
bound up in the wood but what would happen
if we were to spin the saw up first
before we induced the kickback event?
This graph is stinkin' awesome and it tells the whole story.
Let me walk you through it.
Okay, if you look back here on the left
you can see this red spike.
That's when the motor was first spun up.
That's the torque associated with accelerating
that blade rotationally, right, so as we move along
here and we bump the front of the saw, that induces
a kickback event and you can see that in the data
by this large yellow acceleration and at that point
that tells the algorithm oh, oh, there's kickback
and so it applies the brake and you can see
this red spike in the magnetic field.
That is the saw's brake being applied and trying
to stop that rotation of the saw blade
so you can actually see that happening and it tapers
off as the velocity of the saw blade decelerates.
This is awesome.
I mean like high five.
We just used science to stop a kickback event.
Well, I mean, it's even cooler because it's
high five and not high four which is what could happen
if the kickback, I'll shut up now.
- Okay, here's the final test.
I know how to run a circular saw the correct way
and I also know how to do it the wrong way
so I'm gonna try to induce kickback, with the algorithm
running, from my hand and see what happens.
Okay here we go.
It stopped.
This should be on saws.
If you can detect the profile of a kickback event
in Newtonian physics then you can implement
the brake that's already on the saw.
- Yeah, so the brake's already in there.
All you need is a little sensor to figure out
when to hit the brake and that's all we're doing.
- Yeah so if you think this needs to be in tools
please tweet this video to your favorite tool
manufacturer and then tool manufacturer,
come talk to us.
We'll put a link down in the video description.
- Wait till you see the chainsaw experiment.
(beep)
- I'm about to tell you something
that's a pretty big deal in my life.
It's a book called Seven Eves by Neal Stephenson.
I listen to it on Audible which sponsored this episode.
You can get Seven Eves by Neal Stephenson
by going to audible dot com slash smarter
or texting the word smarter to 500 500.
The moon blew up without warning, and for no apparent reason
which is like the best opening line to any book
for my brain ever.
The whole premise of the book is the moon is exploded
and humanity has to get off the earth.
The technology developed in order to do that,
we could totally do this.
There's a swarm of spacecraft in orbit
and if you change your orbit on one side of the earth
just a little bit that affects it on the other side
as well, right?
But if you have a swarm you have to account for all of that.
They developed something called the perambulator
and I read this book like eight months ago.
I still think about the perambulator because
the orbital mechanics hold true.
Whip dynamics, there's artificial intelligence
used in robots to help mine asteroids.
It's amazing so I know there's supposed to be a movie
adaptation of this book so Ron Howard, if you're listening,
I wanna be in the movie.
Whatever, I'm not faking this.
I really like the book.
I love the fact if I'm listening while I'm driving
which is how I listen to audiobooks,
I can swipe my finger and tap a button
and that's how I can save an audio bookmark.
I can listen to it later.
It's an amazing book.
Seven Eves by Neal Stephenson.
Get this by going to audible dot com slash smarter
or text the word smarter to 500 500.
That book will change your life and it'll change
the way you think.
The thing I like about this is it's gonna make your
life better and that's why I love my collaboration
or partnership, whatever you wanna call it,
with Audible, they're rad.
If you're the kind of person that subscribes
to YouTube channels then I hope you would please
consider doing that with Smarter Every Day
if you feel like this kind of content earns it.
If I've already earned your subscription
then I would like to try to work on convincing
you to click the bell because the next few videos
are redonculous, like, we're starting with rocket saw
and it just goes up from there.
It's gonna be amazing.
If you wanna learn more about the stuff Chad and I
are doing together, we call it Lantern Safety Kinetics.
There's a link down in the video description.
The idea is to put brains in your hardware
and make stuff safer.
Thanks for watching these videos.
I really like making 'em and I hope you like 'em too.
I'm Destin, you're getting Smarter Every Day.
Have a good one, bye.
(gentle music)