Looking for a sensor or devise, that indicates a forward and a reverse movement

[tecjim]

Does anyone know of a devise or sensor that can indicate a signal or no
signal for a forward movement, but have a signal for a reverse
movement?
Or is it impossible to do?
I am open to any other solutions that someone can tell me

Description of project is that
1. It has a flat surface to mount to
2. It has wheels for mobility for the movement of a forward or reverses
(push or pull)
3. Power supplied 12v DC 20amp
4. To be used for out-door use, subject to extreme weather conditions
and temperatures.

Example:
Take a child's red wagon being pulled or pushed in different
directions.
Pull the wagon towards you and walk "prefer a signal
Stop "prefer a signal
Push the wagon backwards "signal "
Now pull the wagon towards you and walk "prefer a signal


The specs should fall into this area
Sensor Specifications:

1. Bi-Directional
2. 1-3 phase signal, reverse motion and stationary (non movement)
3. Generate a signal reverse or opposite direction from a forward
motion
4. Time delay adjustment
5. Temperature rating -40°C - +50°
6. .5v - 12v DC .01amp
7. Sealed unit
8. Weather proof
9. .002% accuracy
10. Vibration tolerance adjustment
11. To be used in an external application only
12. No moving parts or external reference
13. Non magnetic
14. PC programmable

Something like a digital compass? I'm not that experience in this field

 

[vic]

12. No moving parts or external reference

This requirement as I understand it makes it impossible. You want to
measure movement relative to a surface, then you *need* a reference. You
could try to use an accelerometer, but it only measures variations of
speed, not the absolute value.

vic

 

[Greg Neill]

---------------Begin Quote------------------------------------------
The specs should fall into this area
Sensor Specifications:

1. Bi-Directional
2. 1-3 phase signal, reverse motion and stationary (non movement)
3. Generate a signal reverse or opposite direction from a forward
motion
4. Time delay adjustment
5. Temperature rating -40°C - +50°
6. .5v - 12v DC .01amp
7. Sealed unit
8. Weather proof
9. .002% accuracy
10. Vibration tolerance adjustment
11. To be used in an external application only
12. No moving parts or external reference
13. Non magnetic
14. PC programmable

Something like a digital compass? I'm not that experience in this field

---------------End Quote------------------------------------------

That's a lot of specs, but they're not exactly clear.

In (1) What's Bi-Directional mean? Are you saying that
your moving object will move only along a straight line
(linear)?

In (4), what's the characteristic of the time delay?
Delay after what, and for how long?

In (9): .002% accuracy with respect to what? You haven't
said what your units of measurement are, or what the
expected range of motions will be (you gave the "example"
of the red wagon, but that's only an illustrative
example, right?).

In (10), what sort of vibrations are you expecting?

 

[Greg Hansen]

Does anyone know of a devise or sensor that can indicate a signal or no
signal for a forward movement, but have a signal for a reverse
movement?

2. It has wheels for mobility for the movement of a forward or reverses
(push or pull) ....
7. Sealed unit
8. Weather proof
9. .002% accuracy
10. Vibration tolerance adjustment
11. To be used in an external application only
12. No moving parts or external reference
13. Non magnetic
14. PC programmable

Something like a digital compass? I'm not that experience in this field

It has wheels. You've already shot the "no moving parts" condition, so
you might as well put a speedometer on it. An optical encoder is
non-magnetic.

 

[Chris]

Does anyone know of a devise or sensor that can indicate a signal or no
signal for a forward movement, but have a signal for a reverse
movement?
Or is it impossible to do?
I am open to any other solutions that someone can tell me

Description of project is that
1. It has a flat surface to mount to
2. It has wheels for mobility for the movement of a forward or reverses
(push or pull)
3. Power supplied 12v DC 20amp
4. To be used for out-door use, subject to extreme weather conditions
and temperatures.

Example:
Take a child's red wagon being pulled or pushed in different
directions.
Pull the wagon towards you and walk "prefer a signal
Stop "prefer a signal
Push the wagon backwards "signal "
Now pull the wagon towards you and walk "prefer a signal


The specs should fall into this area
Sensor Specifications:

1. Bi-Directional
2. 1-3 phase signal, reverse motion and stationary (non movement)
3. Generate a signal reverse or opposite direction from a forward
motion
4. Time delay adjustment
5. Temperature rating -40°C - +50°
6. .5v - 12v DC .01amp
7. Sealed unit
8. Weather proof
9. .002% accuracy
10. Vibration tolerance adjustment
11. To be used in an external application only
12. No moving parts or external reference
13. Non magnetic
14. PC programmable

Something like a digital compass? I'm not that experience in this field

Hi, Jim. Your wish list is full -- I'd guess you're going to say you
want it to be less than $3.50 in single quantity, too. You have a very
specific and rather generous specification list. Some of your specs
are kind of obscure. For instance, what do you mean by .002% accuracy?

Just going from your spec list, I'd suggest you'll get the closest by
doing a quick wallet biopsy, then calling up the good people at BEI and
ask about specialty optical encoders. You could power your encoder and
a special automotive temp range single board computer in a sealed
enclosure, and program the SBC to provide the logic functions. I'd
suggest that 5 to 10 watts is a more realistic power budget, though.

For a real world low current application, you would typically see a
cheapie optical encoder mounted to one of the wheels or, much more
likely and more inexpensively, a few magnets mounted on one of the
wheels with two hall effect sensors mounted out of phase such that you
could get direction from quadrature.

Hall effect sensors are pretty much impervious to cold (although -40C
is a stretch for the rest of the electronics), and would be the device
of choice. And if there's a chance of dirt or snow gumming up the
works, you'd pretty much be limited to hall sensors. You obviously
can't use slotted optointerrupters in an environment where something
could block the slot.

Possibly you might want to talk a bit about your application, and we
can work through the specs and find out what you need and what you can
live with. And by the way, what do you have against magnets? They're
noble devices that are impervious to cold, are energy efficient and
don't wear out.

Cheers
Chris

 

[Kurt Krueger]

It has wheels. You've already shot the "no moving parts" condition, so
you might as well put a speedometer on it. An optical encoder is
non-magnetic.

How about an optical mouse?

 

[tecjim]

It has wheels. You've already shot the "no moving parts" condition, so
you might as well put a speedometer on it. An optical encoder is
non-magnetic.

Unfortantly I cannot use the wheels a a referance point
No machincal devises

 

[[email protected]]

Unfortantly I cannot use the wheels a a referance point
No machincal devises

You sound like my wife. An impossible group of restrictions and won't
tell me what the real goal is. SO what IS the real goal here?

GG

 

[Chris]

You sound like my wife. An impossible group of restrictions and won't
tell me what the real goal is. SO what IS the real goal here?

GG

Second the motion. tecjim has given a poorly defined set of
requirements without describing anything about his application.

The plain fact is, there isn't any magic blivet that will do everything
on his list, even with a generous interpretation of his requirements.
It's his part here to pony up and describe a bit about what he's doing,
and why none of these ideas are valid. Possibly then someone on one of
the ngs can walk through some of the tradeoffs, and he might get
directed toward a best fit, whether it's quadrature hall effect
sensors, quadrature optical encoder, GPS, ultrasonic ranging sensor or
capacitive/inductive sensor. He hasn't given the distance range, or a
real number for the resolution (0.002% of 100 miles on a railroad
track, 0.002% of one revolution of a 1" dia. wheel). To be honest, I'm
not even sure from his description if the device is supposed to be
mounted on the "wagon" or externally, what kind of output he wants, or
where it's supposed to go.

If he doesn't want to take that step, he'll just have to accept that he
can't be helped here. I don't believe anyone on the sci.electronics.*
newsgroups is forced to help on a query where someone just demands
something that doesn't exist, without explaining why he needs it.

And if it's proprietary, he'll have to hire somebody instead of casting
about for free suggestions. There are several well-qualified engineers
who post regularly on both s.e.b. and s.e.d. that are capable of
helping him design a solution. He can have them sign a non-disclosure
agreement, which will keep them from spilling the beans about his idea.
But he will have to give more information to the engineer, and I
pretty much guarantee that there will be some tradeoffs and he won't
get everything on his shopping list.

Since tecjim seems to be new to this, he should know that it's
considered good
form to bottom post, and also good form to crosspost to several groups
(if you must) rather than individually post to several groups. There's
no point in making this several conflicting conversations when one will
do. He should please check out Google Groups Help Topic "What's good
'netiquette' when posting to Usenet?"

http://groups.google.com/support/bin/answer.py?answer=12348&topic=250

Cheers
Chris

 

[tecjim]

You sound like my wife. An impossible group of restrictions and won't
tell me what the real goal is. SO what IS the real goal here?

GG

Due too this application, I realy can't give you much more
then,,,,,,,,,,,I want to place a devise or senor on several moving
applications. I need to recieve a signal of any type when this (wagon)
is moving in the opposite direction, Would also like a foward or netual
signal. I will program the rest of the board and software myself. I
know it has wheels, but due to different manufactures and Liablities
are a consered, I can't use the wheels. Believe me, I wouldn't be
asking for help. It has to be a universal devise!

Thanks for your info.
Jim

 

[Chris]

Due too this application, I realy can't give you much more
then,,,,,,,,,,,I want to place a devise or senor on several moving
applications. I need to recieve a signal of any type when this (wagon)
is moving in the opposite direction, Would also like a foward or netual
signal. I will program the rest of the board and software myself. I
know it has wheels, but due to different manufactures and Liablities
are a consered, I can't use the wheels. Believe me, I wouldn't be
asking for help. It has to be a universal devise!

Thanks for your info.
Jim

Well, Jim, then I guess we're stuck. One of the basic ideas of a
sensor (the center of what you're asking) is that it has to have
something to sense.

If you've got a "wagon", and have to mount a device to sense movement,
it really has to be movement in relation to something. If you don't
have anything at all, GPS (Global Positioning Satellie) information is
available, but that would only have accuracy to yards or meters.
You're the "something", and the sensor is in geosynchronous orbit --
too far away for any real accuracy, unless as I said you're talking
about miles here instead of inches. No precision.

The other option you might want to consider is using a video camera and
doing a video capture of the ground immediately below the "wagon". But
that would have limitations on a uniform surface or on snow, and be
very processor-intensive.

Both of these blow your 120mW (.01A * 12V) power budget out of the
water, of course.

You might want to consider spending a few bucks and setting up an
appointment with an electronics engineer. For a couple of billable
hours time, he can sign a standard legally binding non-disclosure
agreement (downloadable from many sources), you can explain your idea
in detail, show them your sketches, and they can tell you what you can
realistically expect from the world of today's modern electronics.
You'll be able to get an expert opinion on this in one morning, and pay
less than $300 USD with change for coffee. And you'll get a
comprehensive answer you can trust.

Good luck
Chris

 

[[email protected]]

Does anyone know of a devise or sensor that can indicate a signal or no
signal for a forward movement, but have a signal for a reverse
movement?
Or is it impossible to do?
I am open to any other solutions that someone can tell me

Gyration has a wireless mouse that the user simply waves around in the
air.
http://www.gyration.com/en-US/Products.html
http://www.extremetech.com/article2/0,1697,1128548,00.asp

It looks like the IEEE has done at least one paper on cost-effective
inertial motion sensors that might be informative. You might want to
spend a few days in your local, university library and see what you can
find out.
http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=303402

 

[Jamie]

Unfortantly I cannot use the wheels a a referance point
No machincal devises

i know i mentioned this before, "Doppler type unit"
i don't know your surface area's below the wagon how ever,
have you thought about using a motion a motion detector where
is, it aims a Transmitter of Ultrasonic to the floor and then
a receiver picks it up.
something simple, like a LM1496 chip (Double balance Modulator) can
reproduce phase angle output results depending on the direction of
movement.

but like i said, i don't know your surface's that your riding on.

 

[Randy Day]

Jamie wrote:

[snip]

i know i mentioned this before, "Doppler type unit"
i don't know your surface area's below the wagon how ever,
have you thought about using a motion a motion detector where
is, it aims a Transmitter of Ultrasonic to the floor and then
a receiver picks it up.
something simple, like a LM1496 chip (Double balance Modulator) can
reproduce phase angle output results depending on the direction of
movement.

but like i said, i don't know your surface's that your riding on.

I know! Strap an optical mouse to the underside!
That way he can get side-to-side *as well as*
forward-reverse!

<g>

 

[Jamie]

Jamie wrote:

[snip]

i know i mentioned this before, "Doppler type unit"
i don't know your surface area's below the wagon how ever,
have you thought about using a motion a motion detector where
is, it aims a Transmitter of Ultrasonic to the floor and then
a receiver picks it up.
something simple, like a LM1496 chip (Double balance Modulator) can
reproduce phase angle output results depending on the direction of
movement.

but like i said, i don't know your surface's that your riding on.

I know! Strap an optical mouse to the underside!
That way he can get side-to-side *as well as*
forward-reverse!

<g>

yeah rite!