Precision guided disc golf launcher: noobs are now pros

a few years ago I made this dis

launching Gauntlet it was supposed to

make me better at disc off but it just

kind of ended up being

dangerous I couldn't let that stand so I

made

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this it's basically a disc bazooka this

thing is designed for accuracy it has

full control over the speed and spin of

the disc and once we get sights on it it

should be able to snipe the basket and

I'm hoping it can make me as good as a

pro it's also insane L powerful it can

shoot a disc faster than any human so

we'll definitely be having some fun and

shooting it at stuff and yes that's a

sword I'm also going to show you the

trials and tribulations of getting this

thing working and you're in for a treat

because it was terrible it really wanted

to tear itself apart and it refused to

work in reality the way that theory said

it should so I had to rebuild and

rebuild and rebuild it has so many parts

now that I have this I think there might

be a simpler way to do it but is there a

cooler way I don't know this is pretty

cool if you're not familiar with this

golf it's very similar to real golf

except instead of getting a golf ball

into a hole you're trying to get a

frisbee into a basket the second most

important thing to know about Disc Off

is you never call it a frisbee it's a

disc frisbees are for babies discs are

for men and at the end of the day you're

trying to get the disc into the basket

with the minimum number of throws the

discs fly like little airplanes so any

variation in wind or how you launch them

can make them go to completely different

locations in fact I think it's

physically impossible to consistently

get hole in one so my goal is for this

to make me as good as a pro get to the

basket in a couple of throws and then

snipe it in to do this we need accuracy

which means launching discs with very

controlled speed and spin so with all

this in mind I went back to the drawing

board and came up with a completely new

design this is my kids Hot Wheel set

it's a so my general idea specifically

this little box down here has two wheels

that rotate in opposite

directions and if we push a car into it

it launches it super fast this should

work with a disc as well this is a mini

little fake Disc Off disc watch what

happens if we shove it into the

wheels oh wow no

way oh so close what's really cool is

you can make it spin

by making one of the wheels go faster

than the other but there is a problem

there's a limit to how fast you can make

a car or a disc go with this kind of

setup let me show you what I

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mean I've modified the Hot Wheel track

to take this die

grinder before it was launching cars at

maybe 10 m hour on paper this should

give us closer to 40 what do you think

is going to happen

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pretty much the same speed here it is in

slow motion do you see the

problem the launcher wheels are just

slipping the same thing happens when a

car does a burnout it doesn't matter how

powerful your engine is if you ain't got

the grip it's just going to slip but

imagine if I took 10 of these launchers

and put them in a row the first one

would get the car going fast the second

one faster and on and on and on it's

basically a mechanical rail gun so if we

did this and precisely controlled the

velocity of all the wheels we could

launch a disc with whatever speed and

spin that we want all right let's get it

made the hardest part of this project is

going to be how do I grip the disc I

want to put a ton of force into it but

it's really hard to do that so this is

the simplest possible Arrangement that I

could build that will let me try

different kinds of Wheels gripping the

disc so we're going to just shoot the

disc out see what happens go from there

so do you think it's going to work here

we go

[Applause]

I probably should have put a little bit

more effort into it this is a great

example of how destructive vibrations

can be I'm going to have to be really

careful with

this well I'm glad I put the minimum

effort into this thing because it

stinks remember how I made a big deal

about slip yeah if you look closely

you'll see the disc bending when it goes

between the wheels this means I can't

squeeze the disc any harder because

it'll just bend more every time I launch

a disc you can just smell burning rubber

burning plastic so we're slipping we

really need a better way to grip these

discs the direction I was going in is

trying to grip the end of the disc with

a V kind of like a v- belt pulley but

thinking it through it seemed really

hard to do practically but then I was

thinking well if we put the wheels on

top and bottom that's kind of like a vwh

with these I can squeeze pretty much as

hard as I want so I can generate an

enormous amount of friction we'd still

put a set on each side of the disc so we

can make it spin but we don't actually

need a tire on the bottom we just need

something slippery to squeeze

against before we can make the whole

thing I need to test it I need to see

how much grip we can get and see if it

can actually

work these rollers are the slippery

surface we're going to push the disc

against I really like how the wheels are

folded on top they push the disc through

and by driving them different speeds we

can still make it spin so hopefully this

will suck the disc in and spit it out

like it tastes terrible let's

see pretty clear the discs just aren't

getting any spin they're coming just

straight out which makes them very

unstable we need the disc to spin so it

acts like a gyroscope and resist turning

over the wheels driving at different

speeds should be able to spin the disc

but when the disc goes between two sets

of Wheels it's touching four wheels at

the same time and it can't spin it gets

totally locked you can see how much the

tires are rubbing on the disc when this

happens I think what I need to do is

spread these wheels out so that the disc

isn't touching more than two wheels at

any given time so we're going to

redesign and remake a bunch of these

parts to stretch it out like a limo and

see if we can get that to work it's

pretty much the same thing just slightly

different like twins there's enough

space between the wheels for the disc to

spin freely without jamming up really

not a lot to see for so much work but

hopefully it'll make all the difference

so let's find

out okay that is totally spinning it's

not perfectly stable but it's way better

and we should get more spin with more

stages based on the speeds I'm getting

out of the test stand I think I need six

stages but I'm going to make eight just

to be safe the wheels are really hard so

I'm going to get them done

first this was harder to make than I

expected vibration is a huge problem so

everything had to be machined extremely

accurately and even after all that

effort everything had to be carefully

balanced I spent a lot of time designing

them to be easy to assemble because

there's so many of them which really

saved my bacon because I ended up

rebuilding these things so many

times there's a really important detail

that I've been glossing over which is

how much power we need out of the motors

and if you do the math you actually need

basically this motor inside of every

single wheel and this is the motor that

I'm using it is a little bit

underpowered every motor will have a

chunk of Steel attached to it that looks

like this it's called a flywheel this

will spin up with the motor and store a

ton of energy think of a car that's

moving fast or a cannonball once it's

going to stop it you have to take all

that energy out the neat thing about a

flywheel is it can deliver an enormous

amount of energy in a very short amount

of time kind of like a car hitting a

wall it's pretty amazing but this little

piece of Steel can deliver as much power

as this motor for a couple milliseconds

but that's all we

need the rest of the machine is really

similar to the previous ones there's

just a lot more of everything I've

actually had this idea for 2 years but I

was waiting until I got the water jet

because I knew there was going to be a

lot of parts like this trying to machine

all these in another way would be such a

nightmare

thankfully a bunch of the parts could be

3D printed because there are so many

parts I designed the whole thing to be

three modular sub assemblies that

combine together like a Transformer to

make a mighty launcher this makes it a

lot easier to assemble and if I destroy

something it's a lot easier to repair do

you remember those 5ft subs from

elementary school they'd bring to

parties that's basically what this is

the biggest change is this thing I don't

love having a long thing hanging off the

back of my disc launcher but I think

it's really important we want the disc

to come out very repeatably which means

we need to put the disc in very

repeatably you can imagine if it was

angled up or down it'll bounce through

the system and come out differently this

is kind of like a mini launcher that

back and it holds the disc and

then when the computer's ready to fire

it'll release it and push it nice and

straight with some momentum right into

the launcher the disc is held back with

a trigger mechanism which is really

important for releasing the disc when

everything is going exactly the right

speed and getting consistency it also

has handles for picking it up like this

it's not that heavy and then

electrically there's just basically 16

of everything which was painful and

expensive and of course there's knee

stop because if things go wrong you want

to make them stop going wrong fast

although there is a big problem if I

turn all the motors on at the same time

they're going to be pulling an enormous

amount of current trying to spin up

their fly wheeels and it's going to be

like 400 amps which will just melt

everything the battery will explode

it'll probably start a really foul

smelling fire so I have to do a little

more complicated thing where I spin them

up kind of one at a time and that should

limit the current to something more

manageable and then it also has a

computer running Linux with a

touchscreen which might seem Overkill

but I'm planning to add a lot more

smarts into this later this is going to

give me an interface to make me way more

accurate the last thing we need is some

software that'll calculate how these

motors all need to spin to make the disc

go the way that we want it to and

there's a lot of different strategies to

do this the most obvious way would be to

evenly split the acceleration between

all the wheels but this doesn't really

work because physics the amount of

energy it takes to make something go

from 0 to 30 mph is the same to go from

85 to 90 mph you might remember the

whole 1 12 MV squared thing this is that

which counter intuitively means I need

each stage to speed the disc up less and

less but this should actually evenly

spread the load and give me the maximum

amount of grip and that's pretty much it

it's simultaneously not that bad but

also kind of complicated I think it

should work but there's really only one

way to find out so here we

go here we

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go all aboard next stop integration hell

when you put all the pieces together it

never works I started off Strong by

blowing up half the motor drivers but

even worse it's throwing discs even

worse than

me I thought we fixed this I see a lot

of problems the first is the disc doing

this it's not supposed to swim like a

whale it looks like the disc's able to

dip down between the rollers and then it

pops up and then develops a really bad

oscillation basically a bucking bronco

[Music]

so I'm going to try to put a guide right

down the middle and that'll hopefully

stop it so let's

see oh yeah that was way

better the guide rails totally work but

there's another really big problem that

I really don't want to solve if you look

at the disc closely it's not really

spinning we to shoot it far it's just

going to flip over and slam into the

ground ask me how I know I think this is

because I don't have good control over

the speeds that the different Motors go

if they're going the wrong speed the

disc is just going to do random stuff

and this is happening because I'm using

cheap motor controllers that have very

bad speed control if I tell them all to

go the same speed they all go different

speeds we could either buy thousands of

dollars worth of nice motor

controllers or we could do some really

annoying engineering that I don't want

to

do all right so I've been doing some

engineering and this is what I came up

with what I'm going to try to do is

measure how fast each wheel is rotating

using one of these this is called a hall

effect sensor and it detects a magnetic

field so I have one set up right here

wire to this light and if I bring a

magnet near it it will detect it and

turn this light on if we strategically

place a magnet on each wheel and put a

hall effect sensor nearby it we will see

that magnet every time it spins by so

now if the motor controller is going the

wrong speed we can quantify how wrong it

is and compare it to the speed we want

it to go and adjust the speed we're

telling the motor controller to go until

the speed it's actually doing matches

what we want we have to install and wire

in 16 of these because they're 16 of

everything this is getting ridiculous so

the hall effect sensors work but it

still doesn't work because these

motor so watch what happens when I try

to go 1,000 RPM which is a very

important RPM for me to be able to

[Music]

go the motor drivers will not go below

2500 rpm so I think the right thing to

do would be to get motor drivers that

can go the speed that I want but we're

in pretty deep now so I think it's time

to go full sunk cost fallacy and just

try to fix this in software so here's my

plan if I want a motor to be going slow

when I fire I can just turn it off

before I fire and let it slow down and

right when it hits the right speed boom

you're fired but It's Tricky with

multiple motors going different speeds

because they need different times to

slow down but I can have the computer

calculate when to turn each motor off so

they all reach the right speed at the

same time and when that happens you're

fired and when it works it looks like

this you have all the motors going a

precise speed to make the disc do what

we want and it's so cool

my wife is here to see what I've been up

to what do you think looks been

complicated I thought this was going to

be easy no I think that I know but I

really thought it like it's always think

that it's a bunch of Wheels how hard

could it be you know there's nothing to

it turns out there was something to it

you want to press the buttons you see

what this thing does oh thanks are you

sure yeah you don't want to fire it no

how do you not want to fire it I want to

see what happens you got to admit pretty

cool yeah you look totally normal take

it on over to the old disc golf course

see what happens you look like a vendor

selling uh Wheels instead of hot dogs at

a game

popcorn get your

popcorn all right so you ready to see

the

future here we

[Music]

go on buildups you're very sh

[Music]

off that sounded good

goody I

know

why I thought I was done but instead I

got 2 weeks of pain this has been

driving me insane it was spinning before

now it's not but I think I figured out

what's going on it's almost the same

thing as before where the disc would get

locked between four wheels but it can't

physically touch four wheels but I did

increase the compression of The Wheels

on the disc so now they're making first

contact with disc here instead of here

which is really good at stopping Spin

and I've tried so many things to try to

mitigate this but most of them didn't

work so we're not going to go into all

the details but here's a little taste

first I tried to fix it in software with

about 10 different disc acceleration

strategies they didn't work I tried so

many things related to friction and

wheels I thought for sure this was going

to work

but it didn't I also thought for sure

this was going to

work but it

didn't don't even ask you know what

really stinks having 16 of everything

but I had an epiphany last night and I

think I figured it out so let's see

[Music]

finally you can tell it's working well

when the discs drive across the net like

a car all of my fixes are based on the

idea that it takes a lot less energy to

get the disc spinning than moving fast

laterally so I'm splitting the boosters

into two groups spinny ones not spinny

ones the first four stages don't attempt

to spin the disc they just accelerate it

as fast as possible and then the fifth

stage starts at spinning in the last

three stages only have a wheel on the

left and if you think about it since

it's pushing on the edge this will push

the disc forward but it'll also spin it

and if you only have a wheel on the left

side it doesn't lock up so all these

things together let me get it going

really fast with a ton of spin so one

downside with the front wheel

Arrangement is that we can only spin the

disc one way but I don't think it's a

big deal something I want to fix but for

now you can make the disc go as fast as

you want with as much spin as you want

as long as it's clockwise

wise all right it's time to touch grass

go outside and find out what this thing

can do

[Music]

[Applause]

[Music]

whoa

[Music]

wow this is far exceeding my

expectations it's possible because I set

them low but I'm just firing from the

hip with no sights and I'm getting the

discs to land really close to each other

I can't imagine how good it would be

with

sights it's also really cool because

it's showing how discs launched the same

way can fly completely differently

depending on their air foil shape but

don't forget we can also change the

speed and spin this has a huge impact on

where a dis flies and is going to be

challenging for predicting where discs

are going to go all right it's time for

more speed

so I think we may have found the speed

limit I ripped apart one of the wheels

and then I fixed it and we ripped

another wheel off its rim and then I

fixed it and we ripped another wheel off

its Rim around 90 mph is where these

wheels just say they can't take it

anymore this is the sound of the wheel

giving

up I don't want to destroy everything so

I'm going to stop while I'm ahead but we

got a few good shots in and we're

getting about 450 ft at 9 mph I think I

should be able to do better than that

but there's a lot of things that can

make you go short so the problem I have

is that I can't aim this thing because I

don't know where the discs are going to

go they're like little airplanes and

depending on their speed and spin and

air foil shape they fly in completely

different ways so the first question is

if we shoot the same disc in the same

way does it go to the same place so I

built this really over engineered test

stand to prove it to myself I did a lot

of testing

as expected it can't get a hole in one

every time but it's pretty good and

sometimes it

[Music]

can

oh and besides if I can get even

remotely close to the basket I should be

able to just snipe it in we'll have to

work on the speed though I don't know

how discs fly I'm going to have to make

a thing to track the discs so I can get

a lot of data and then if I combine that

with some software which will show me on

a map where it's going to go I can make

some really nice sites that should let

me play a really good game of disc off

this video is already really long so

we're going to do that in part two so if

you're interested in that make sure that

you subscribe so you don't miss it and

we're not done yet though because I have

a thing that can shoot discs really fast

when you have something that can make

stuff go really fast you have to put

stuff in front of it like I have to know

what happens if I put this machete in

front of a disc coming out of this we're

going to find out

I just got up it's way too early to be

filming but I wanted to show you what I

do every day I think this is one of my

superpowers and it can be yours too so

let me show

[Music]

you that's good no matter how busy I get

I spend at least 30 minutes a day

learning something new this is how I've

picked up a lot of my skills and one of

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it just taught me some Theory and now

it's having me do some examples so you

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out all right let's blast some stuff

with some discs it kind of goes without

saying but don't try this at home and

this is exciting enough that I invited

my wife over for the festivities are you

as excited as I am probably not but I am

excited no one knows what's going to

happen what do you think is going to

happen I think the frisbee is going to

it's called a

disc it's not going to go all the way

through or something I think it's going

to be the most amazing thing you ever

saw after me with this one you need to

go hide outside or something because you

don't want an errant disc to the belly

I'm willing to take an errant disc to

the belly I'll Flex when I fire and

we're going to do it in three two one

[Music]

[Applause]

that's got to go on the wall for sure

that is cool I was expecting that very

cool very

cool are you impressed with me yes

always are you impressed with this

mostly it sliced a disc in

half I think this could legitimately

make me really good at DIS off if you

count using a bazooka playing Disc Off

yeah it's not a discreet way to cheat

yeah I don't know how you'd hide this

under a trench coat or something exactly

what I was thinking anyway disc launcher

or all right we're done

[Music]