Fiberoptic joystick with quadrature encoders and arduino--- make money online

hi everyone I thought I'd show you my

latest project this is a standard

computer joystick that's not that

interesting but this particular joystick

is entirely optical so there is no wires

inside here this is only glass fibers

inside this cable meaning that the

joystick has no electronics inside her

this part of it is completely free of

electronics why would you want that you

may want to put this joystick into an

environment where you cannot have any

electricity for either safety reasons or

in this case this joystick is going to

be used inside MRI and an EEG machines

so you don't want wires in those

environments because it might interfere

with the magnetic field or may cause a

safety issue in those environments so I

developed this joystick that is entirely

metal free actually there's no all the

fasteners are plastic and as I mentioned

the sensing method is entirely optical

so this cable contains a total of eight

fibers and this is an NPO MPO connector

which is an industry standard for

multiple fiber optics in sort of one

connector so typically these have 12

fibers in them as this one does but I'm

only using eight and it all snaps

together like that and I bought this

pre-made cable which breaks out the

eight fibers into individual lines and

I'll show you inside this box so you can

see where those fibers go here's all the

electronics inside the interface box I

guess I'll start on the optical side

over here we have eight optical fibers

four of them are transmitters and in

this case the transmitters are just on

all the time it's not really sending any

data so there's just a couple of current

limiting resistors and I think I set

them to about seventy five milliamps for

each one of those transmitters so it's a

fair bit of power and I'll put up a link

to the

to the datasheet on these parts so then

we have the receivers over here this

company Ave ago or a vago or whatever

makes a bunch of optical components and

they make two versions of this receiver

this particular one has a trigger in

there and it's meant for low-speed data

communications so the output swings from

0 volts and then is supposed to snap

very quickly up to 5 volts I found that

they don't actually snap all that

quickly if the input optical signal is

kind of slowly changing you can get

these parts to not suddenly switch but

anyway what you essentially get is a

square wave out of these that tracks the

input and it's it's set somewhat

arbitrarily so when the input power goes

over a certain threshold the signal out

of these switches so what we have is for

plain old square waves from these

receivers and that gets fed into a chip

also made by a vago and this is a set of

counters and quadrature decoders so that

as the signals change in here the

counters count up and down and the

reason I chose to use this chip is

because you can clock it pretty quickly

over here I've got a five five five

circuit running at about a hundred

kilohertz and so this chip uses the

hundred kilohertz clock signal to figure

out the state transitions in the

quadrature signals you could go much

faster this chip can handle clock rates

up to about 33 megahertz however I found

if you clock at that fast it will pick

up noise and you know tiny little

twitches and stuff in these signals and

it's just not helpful so by lowering the

clock signal you can actually make the

system more noise resistant and in this

case having 100 kilohertz clock is

plenty fast to you know capture the

movement from the joystick okay so once

the counters in here are synced up with

the movement of the joystick the Arduino

samples the values from this chip it

reads them out in a the

segments that's a 32-bit counter for

each channel so it reads out a bunch but

I think I only asked I'll put some more

details at the Arduino Kota but I only

only read the last two bytes because the

there's not enough travel so I don't

really need all 32 bits and the main job

that I was using the Arduino to do is to

keep track of the minimum and maximum

and automatically scale the output so

one problem with incremental encoders

like this quadrature system is that when

you first power on the device it doesn't

know where the joystick is so you can't

have like an absolute number associated

with it so what the Arduino does is it

captures the minimum and maximum

position for a given session and then

scales the output so that it's always

outputting a percentage of that range so

this would require the user to move the

joystick around into complete revolution

right after powering up so that the

devices the code in the Arduino knows

what the minimum and maximum value is

and then from here I sent that scaled

sort of percentage range to this 80 mega

chip which does USB interfacing so I

realize this is kind of a lot of chips

it would be actually much better just to

have a single 18 mega chip read the

quadrature signals and go all the way

through to USB but in the name of

getting a circuit done quickly and

easily I did it this way and kept the

code pretty simple using modular

components like this allows me to change

things later on to rather than be

dedicated to one specific 18 mega chip

ok so if we turn the joystick over you

can see how it's built inside and we

have the bundle of fiber optics coming

in here and splitting off into the

individual fibers so two of the fibers

are positioned on one side of this

encoder wheel and two of the fibers are

positioned on the other side and they're

set up so that the distance between the

two fibers is a 90 degree phase

difference in the pitch of the encoder

wheel

as the wheel spins the light is broken

up in such a way that it's 90 degrees

out of phase for the two channels and

then you have the same thing for the

other axis so and when I rotate the

joystick handle the movement is you know

split up into vertical and horizontal

rotation and that's what turns the

encoder discs and sends the signal out

the optical cable I chose the the core

diameter 62 and a half micrometers to be

about the width of an encoding segment

on one of these code wheels at the right

radius so as the code wheel turns it

pretty much out almost a hundred percent

occludes the fibre end and that works

out pretty good because you get a nice

strong square wave signal out of the

optical system these are actually

surprisingly tough I wanted to show what

you can get away with one of these

fibers it would seem that a glass fiber

would be pretty delicate but check out

what you can do with one of these you

can really I mean you would never do

this to you would never be able to make

it go this and it's it'll all just snap

back and you can even get a fair bit of

signal this doesn't attenuate the signal

as much as you might think so I'll just

go ahead and break one just so you can

see what it's going to take it's

actually pretty surprising how small the

radius can get before it actually breaks

so if I push on this thing still

together still together try to break it

and I finally snapped as you can see you

really have to try to break one of these

now when you strip the protective jacket

off and expose just the glass fiber then

it gets quite fragile

here's one of these fiber stripping

tools and so if I strip off that

protective jacket and you can just

barely see it but there's the fiber

itself now the thing is pretty delicate

and it I just broke a piece off even

though it's impossible to see and this

is the part where you actually you know

insert the glass fiber into the into the

ferrule like this and I'll put a link to

a video that shows how to do the

termination there and polish the end best way to earn money from home, make instant money online absolutely free, trusted online money making sites, online income site, best online earning, money online, earn money from home, earn dollars online, earn money online, earn money online 2019, earn money online by typing pages, earn money online daily, online work at home and earn money, online earning, earn money online free, online money earning sites, earn real money online, e commerce ideas to make money, easiest way to earn money online, best way to earn money online, make money from home, make money online free, money making sites, earn from home, real ways to make money from home, online income ideas, make real money online, top online earning websites, earn money online fast, top 10 money earning websites, earn money without investment, earn money online for students, best sites to earn money, make money online 2019, earn easy money online, earn money online instantly, real money earning sites, make money from home online, make money online fast, earn dollar online free, online earning ways, best online money earning, earn money online with surejob, make money online, online money making sites, best sites to make money online, earn money online paypal, online earn money by typing, best survey sites, ways to earn money online, ways to earn money from home, make money online without investment, make money online surveys, 

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