Range detector

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MORA99

Senior Member
Any advise as to which range finder modules a picaxe can interface with directly ?
Maybe some of the cheap ones from acroname ? http://www.acroname.com/robotics/parts/c_Sensors.html


I will mount it in a static place and it will monitor distances up to 2meters, minimum is not so important but 30-50cm would be cool.

It will be exposed to a bit of dust, dont surpose you can cover these things, then their sound cant get out either ?

It is to monitor the level in a furnace "container".
 
D

Dippy

Moderator
I don't know which one on that link you're thinking about but lots of people have used the Devantech types, eg:
http://194.201.138.187/epages/Store.storefront/?ObjectPath=/Shops/Store.TechSupplies/Products/SRF005

I don't know whether you can cover them, maybe somone has tried a bit of clingfilm. You could always experiment couldn't you?

But you'd better clarify the comment about "It is to monitor the level in a furnace "container"."
Does that mean it'll get very hot? How hot? (i.e. estimated temperature).
Will it be a corrosive atmosphere?
What is the physical layout? - U/S devices are not very directional.
It could limit your choice and/or your method!

"30-50cm would be cool" - not in a furnace.

I think a posted sketch/drawing would be handy.
 
L

ljg

New Member
All those modules will interface with a Picaxe if the Picaxe in question has I2C.

The SRF04 and SRF02 can be directly connected to picaxe pins for use with Pulsin commands. The modules require 2 pins ea.

Also look at the PING))) sensor from Parallax"
It only requires 1 pin for operation, and its software includes a delay so you can set up Pbasic Pulsin and not worry about the slownwss of interpreted commands

Also look at this offering from HSC supply. MiniS work-alikeThey don't list the manufacturer, but it appears to be Sensecomp, as the Sensecomp miniS data sheets work.datasheet
An actual miniS costs around $60


Nice unit, easy interface, requires only 1 pin for automatic (5 Hz operation, two pins if you dictate when it fires. Good range (over 30 ft) has two fixed ranges that trigger open collector pins. Also has PWM ( use Pulsin) output.
Requires 3 Hits to turn on< three misses to turn off.

Since they use the large transducers the old Kodak units used, they have a narrower beam. The main difference between these and the MiniS is that you can't calibrate these, it's been done at the factory.

The real advantage is the price ($9.95). I've used several. I can't walk into the store without getting a couple more.

I don't think any of these units can be covered, though you may be able to swap out a transducer.

Sensecomp does have units that would be both dust and water proof.
http://www.senscomp.com/products.htm $$$$$
 
D

Dippy

Moderator
Those MiniS etc look nice.

If using a Devantech SRF0x module I wouldn't recommend swapping the transducer/s for a sealed type.
Apart from potential hassle of desoldering from a D/S pcb, Devantech say this in their FAQ section:
"Q. Can we replace the transducers with sealed weatherproof types?
A. No. We have tried these on both the SRF04 and SRF08 and they do not work. The characteristics of the sealed devices requires a new design which is on our future plans list."

But I still think we need more info on 'environment' and physical layout before making suggestions.
 
B

BeanieBots

Moderator
With the exception of the lazer unit, I've used virtually all of those sensors with a PICAXE with little problem.
For range finding, my favourites are the SRF08 and GP2D12.
If you only need one ranger, then the SFR04 would be more cost effective than the SRF08 but the SRF08 does have some extra features that can help in 'difficult' environments.
The GP2D12 would be my sensor of choice for a range 30 to 50cm but that would be for a robot. As mentioned by Dippy, what conditions will it have to put up with? IR ranging might not work at all with a "furnace".
Sealed ultrasonic modules are available and have been discussed before, so a search might reveal from where they can be obtained.
 
M

MORA99

Senior Member
The link from the lag thread seems easy to interface
http://www.maxbotix.com/

They have a adc, pulse and serial :)



The sensor will not get hot, if it does theres bigger problems :|
It will be mounted in top of a container with bio"fuel" (wood pellets mostly) and estimate the distance to the fuel.

But it will be exposed to dust, maybe I can make it so only the transducer is exposed and that can be replaced when it fails.

Heres a (Large)picture of the setup http://h.nirc.dk/fyr/Billede1.jpg
The sensor would be mounted next to the gate over the white box.
 
P

PDO

New Member
As regards a standard servo, I have been using a Futaba S3003. They're cheap, reliable and pretty good for stuff like camera movement, robotic arms etc.

Speed: 0.23 sec/60° @ 4.8V or 0.16 sec/60° @ 6V.
Torque: 44 oz-in @ 4.8V or 56.8 oz-in @ 6V
(3.2 kg-cm @ 4.8V or 4.1 kg-cm @ 6V)
Size: 1.6"L x .8"W x 1.4"H (41x20x36mm) w/o output shaft
Weight: 1.3oz (37.2g)
Connector: "J" type with approx. 5" lead

Ball-bearing servos have less friction, and therefore will have a longer life than standard servos. Metal-gear servos are tougher and hence can be put under more stress/loading conditions and will still hold up.

For a list of servos from a whole bunch of manufacturers have a look here:

http://www2.towerhobbies.com/cgi-bin/wti0097p?CATEGORY=MA

Cheers
PDO
 
M

MORA99

Senior Member
Just a little update, recieved EZ3 from maxbotix today and it works fine with picaxe.
I have only tried reading the serial data, since that seems the easyiest, format is RXXX(13), at 9600, XXX being inches to target 6-255 in ascii.

Seems new 14-m can go to 9600 anyway, so no problem, I tested with a 18x, since my 14-m all have too old firmware.

ADC works fine too, only tested with a DMM, outputs vcc/512 per inch.

As for precision, its beam is a bit wide even for the narrow one I choosed, its good enough to do rough distance measurement, and fairly acurate at 1-2meters distance.
After that the readout is within a feet or so, but at least its fairly stable with the results.

Within 6inch it can no longer estimate the distance, only that theres something, but their datasheet inform of that too.


Oh, and the damm customs got me, that will be 15$ they said :(
 
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