Convert gear tooth sensor square wave output to analog voltage

[[email protected]]

I am trying to design a speed sensor for a FIRST robot. We are using
three wheels on each side and will be varying motor speed on each side
to steer the robot. I plan on using the Allegro gear tooth sensor,
ATS665LSG to sense drive wheel rotation. This gear tooth sensor
outputs a square wave where the pulse repetition interval is
porportional to the speed of the rotating gear. I would like to
convert the pulse repetition interval to an anlog voltage (0-5VDC) that
can be used as a voltage proportional to the wheel speed. One thought
is to input the square wave into a simple op-amp integrator? Any other
design implementations ideas or integratice circuit options? I have
12VDC power available. Thanks!

 

[[email protected]]

Running a square wave into an integrator won't do you a lot of good
because the average voltage will always be the same.

You might try a little microcontroller. You could measure the pulse
width directly and depending on the uC either generate an analog output
or a higher frequency PWM output. This could be a very inexpensive
solution and give you a lot of flexibility. You could probably do all
the wheels with one uC. It would be easy to get direction out of it
too.

Another way you could do it, if you have a fear of uCs, would be to
trigger a one-shot each time you get an edge. Run the one-shot through
an integrator and you have pretty much the same circuit you were
thinking of to begin with.

Either way it should be fairly straight forward. Good luck.

- Tim

 

[martin griffith]

I am trying to design a speed sensor for a FIRST robot. We are using
three wheels on each side and will be varying motor speed on each side
to steer the robot. I plan on using the Allegro gear tooth sensor,
ATS665LSG to sense drive wheel rotation. This gear tooth sensor
outputs a square wave where the pulse repetition interval is
porportional to the speed of the rotating gear. I would like to
convert the pulse repetition interval to an anlog voltage (0-5VDC) that
can be used as a voltage proportional to the wheel speed. One thought
is to input the square wave into a simple op-amp integrator? Any other
design implementations ideas or integratice circuit options? I have
12VDC power available. Thanks!

this may be of interest
http://www.national.com/pf/LM/LM2907.html


martin

 

[Jon]

..
An integrator won't work, but a low pass filter will. It wiil provide
a voltage proportional to speed. AN integrator output would simply
ratcht its way up to op-amp saturation. If you need to also sense
direction, then you will need two sensors.
Regards,
Jon

 

[Genome]

I am trying to design a speed sensor for a FIRST robot.

Ahhhh Well, there you go........

The FIRST thing you should have said is that you were doing a FIRST
robot.....

Not that people know what a FIRST robot is....

http://www.usfirst.org/

I watched/listened the video/audio.....

Strange people, wierd haircuts, old blokes and rubbish......

Seriously, other than the excitement I see no substance.

And you may have problems.

Like the Griff says, have a look for frequency to voltage converters.
Unfortunately you still have to interface it to the other stuff to drive
your FIRST robot and most of the competitions stuff looks like lo-tech so
it's not as if you are going to get much help from your team mates.

So, the cunning idea..... which is why this is crossposted to the slackware
group, is you drop one of those optical mice things on the floor. I have
noticed my optical mouse was cheap and it cute and appears to move the
cursor thing quite nicely.

Install a puter on your robot and do some interface type stuff wiv PID
control. (Can I throw up at that statement?)

Then you can call it SlackBot and place it in the LinuxBot category along
with any challengers from other Linux distributions.

SuseBot
UbuntuBot
RedHatBot
KittyBot
BottyBot

Obviously Bill Gates will get really excited about the idea so he will need
a category called NotMovingBot to cover all of his operating systems.

DNA

 

[martin griffith]

Ahhhh Well, there you go........

The FIRST thing you should have said is that you were doing a FIRST
robot.....

Not that people know what a FIRST robot is....

http://www.usfirst.org/

I watched/listened the video/audio.....

Strange people, wierd haircuts, old blokes and rubbish......

Seriously, other than the excitement I see no substance.

And you may have problems.

Americans generally do the right thing, after first exhausting all the
available alternatives
- Winston Spencer Churchill


martin

 

[Genome]

Americans generally do the right thing, after first exhausting all the
available alternatives
- Winston Spencer Churchill


martin

Oooh, old irrelevent bloke.

Is this some reference to 'Invasion of the Clones'.

DNA

 

[martin griffith]

Oooh, old irrelevent bloke.

Is this some reference to 'Invasion of the Clones'.

DNA

WSC was an arsehole, but did have a fine way with verbs and stuff.
Dunno Invasion of the Clones(never heard of it), prefer the Day of the
Triffids



martin

 

[jasen]

I am trying to design a speed sensor for a FIRST robot. We are using
three wheels on each side and will be varying motor speed on each side
to steer the robot. I plan on using the Allegro gear tooth sensor,
ATS665LSG to sense drive wheel rotation. This gear tooth sensor
outputs a square wave where the pulse repetition interval is
porportional to the speed of the rotating gear. I would like to
convert the pulse repetition interval to an anlog voltage (0-5VDC) that
can be used as a voltage proportional to the wheel speed.

What on earth for?

For interfacing with the microcontroller feed the pulse to a digital
input and have a hardware counter inside the micro, or an interrupt
routine count the pulses.

Measuring speed is a littl;e harder, but measuring distance is much easier
and more precise.

One thought
is to input the square wave into a simple op-amp integrator?

Is it a fixed width pulse?

Any other
design implementations ideas or integratice circuit options? I have
12VDC power available. Thanks!

||
pulses in ---||------+-->|-+-------[R1]-+----+----- speed out
|| | | | |
.->|-' ===== .--[R2]-' =====
| | | |
0V ------+----------+----+------------+-----

Bye.
Jasen

 

[Michael A. Terrell]

Americans generally do the right thing, after first exhausting all the
available alternatives
- Winston Spencer Churchill

America is still here. Where is Winston Spencer Churchill?


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Genome]

WSC was an arsehole, but did have a fine way with verbs and stuff.
Dunno Invasion of the Clones(never heard of it), prefer the Day of the
Triffids



martin

Invasion of The Clones?

It's my new Fuckumentory for the BBC that demonstrates how society and the
world is still controlled by the original evolutionary aspects that underly
mankind.

Episode One looks at what that Manwatching Bloke Said.

Episode Two fucks him over and explains how much we will **** each over for
a bit of life. It's not as if he is not a millionaire now and he did not
give me serious titty picture. That's the evolutionary stuff.

Episode Three examines the phscyciological(?) stuff that underlies the
opportunity for the people who will **** others over for the opportunity to
have a really nice house. Which is what like we have those that are to be
harvested for us nice houses.

In episode Four we discover the concept of the upper upper upper Middle
Class, AKA scum who suck the suck in service of........

The harvestors. The users and abusors. Scum Fucker bastard fucks.

Which is not much different from Episode Five, where I get my PHd and
convert all the other religions to Genomism and everyone dies.

At this point in time no-one notices until I detonate the two polar fusion
bombs followed by the 360 equatorial ones, at the time the compression wave
arrives.

Then I'l go fucking rape all your arses having bought a nice insurance
policy and larf at you fuckers who get to vote like dumb fucks and hate you
for not.....

Giving me a comfortable death.

WHAT A FUCKING SHITTY WORLD

DNA

 

[martin griffith]

America is still here. Where is Winston Spencer Churchill?

Playing around with some alternatives, maybe, bit like Pres. Raygun

Anyway, just been watching the Shuttle land on NASAtv, it seems they
did a monster job at the ISS.
Very Impressive


martin

 

[Luhan]

WSC was an arsehole, but did have a fine way with verbs and stuff.
Dunno Invasion of the Clones(never heard of it), prefer the Day of the
Triffids

Some people are vegiterians, they only eat vegetables.

Triffids are humanitarians, they only eat humans.

Luhan

 

[martin griffith]

On Fri, 22 Dec 2006 23:09:10 GMT, in sci.electronics.design "Genome"

snip oodles of >>>>>>>>>>>>

Invasion of The Clones?

It's my new Fuckumentory for the BBC that demonstrates how society and the
world is still controlled by the original evolutionary aspects that underly
mankind.

Episode One looks at what that Manwatching Bloke Said.

Episode Two fucks him over and explains how much we will **** each over for
a bit of life. It's not as if he is not a millionaire now and he did not
give me serious titty picture. That's the evolutionary stuff.

Episode Three examines the phscyciological(?) stuff that underlies the
opportunity for the people who will **** others over for the opportunity to
have a really nice house. Which is what like we have those that are to be
harvested for us nice houses.

In episode Four we discover the concept of the upper upper upper Middle
Class, AKA scum who suck the suck in service of........

The harvestors. The users and abusors. Scum Fucker bastard fucks.

Which is not much different from Episode Five, where I get my PHd and
convert all the other religions to Genomism and everyone dies.

At this point in time no-one notices until I detonate the two polar fusion
bombs followed by the 360 equatorial ones, at the time the compression wave
arrives.

Then I'l go fucking rape all your arses having bought a nice insurance
policy and larf at you fuckers who get to vote like dumb fucks and hate you
for not.....

Giving me a comfortable death.

WHAT A FUCKING SHITTY WORLD

DNA

You fucked up
The commom format in TV is a threefactctumentary, 40 min program with
3 facts, not always accurate, in it, excluding adverts that extends
the program (?) to an hour.

But in Lost, this is down to 0.3 happenings per episode

You had a storyline..... Failed




martin

 

[Genome]

On Fri, 22 Dec 2006 23:09:10 GMT, in sci.electronics.design "Genome"

snip oodles of >>>>>>>>>>>>
You fucked up
The commom format in TV is a threefactctumentary, 40 min program with
3 facts, not always accurate, in it, excluding adverts that extends
the program (?) to an hour.

But in Lost, this is down to 0.3 happenings per episode

You had a storyline..... Failed




martin

I wrote this for the BBC and you mentioned adverts so you can go ****
yourself.

WANKER

DNA

 

[Michael A. Terrell]

Playing around with some alternatives, maybe, bit like Pres. Raygun

Anyway, just been watching the Shuttle land on NASAtv, it seems they
did a monster job at the ISS.
Very Impressive

martin

It flew over my house about 5:25, on it way to the cape.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida