Re: IR detector system, biasing of photo diode

On a sunny day (Mon, 28 Oct 2024 11:17:56 +0100) it happened Klaus Vestergaard
Kragelund <klauskvik@hotmail.com> wrote in <vfnocj$uluj$3@dont-email.me>:

On 27-10-2024 20:06, Don Y wrote:

On 10/27/2024 7:33 AM, Klaus Vestergaard Kragelund wrote:

On 27-10-2024 14:05, Don Y wrote:

On 10/26/2024 5:19 PM, Klaus Vestergaard Kragelund wrote:

I am working on an IR detector that will guide a robot into a
docking station.
>
A IR transmitter on the docking station transmits a beam, and 2 IR
detectors on the robot detects the beam and lets the robot navigate
towards the target. The working distance is a couple of meters.

>
Can the robot ALWAYS see the docking station?  What happens if an
obstacle (wall?) comes between the two?

>
Yes, we have RTK GPS to position it within a cm at a location right in
front of the docking, 2 meters away.

 
Then why can't you move to the GPS location of the dock with the
same degree of accuracy?
 

>
The docking station is typically in a shed, or close to a building where
the GPS signal disappears.
>

Can either device (robot/dock) ever slip out of the shared plane?

>
No, should be locked

 
"Outdoors" (from below).  Presumably on pavement/concrete (not a "lawn")
that wouldn't have dips and bumps?
 

>
It's moving on grass, and can have bumps etc, so for IR the lope needs
to be perhaps 20degrees to avoid loss of signal
>

Can the docking station be moved, from day to day, site to site, etc.?

>
That is fixed
>

Is the arena indoors?

>
Outdoors
>

I have become particularly fond of using cameras to interface with
the real world.  Of course, it requires a bit more horsepower but
seems to be able to overcome all of the issues that have crept up...

>
That's also a solution we have been working on. The Worx Vision uses that
>
https://eu.worx.com/da-dk/landroid/vision-technology/
>
That is for a future version. Cameras can also be blinded, lenses
needs to be cleaned etc

 
Yes, but a camera can be "queried" to verify that it is functioning
correctly:  "What do you see?  Is it THIS?"
 
I test my cameras by storing previously viewed scenes to verify they
are still "reasonably" intact.  Ideally, I would move something into
the field of view but that requires additional capabilities.
 
You, however, could move the robot (assuming IT has the eyes) and
verify that the scene changes accordingly.
 

>
Could be done. The guys in charge are worried with change of
environment, so what happens when it snows heavily, fog or other
surroundings changing effects.

You could put a RF transmitter in the thing,
and measure for maximum signal with 2 separated receivers, like ham radio fox hunt,
 https://en.wikipedia.org/wiki/Transmitter_hunting
then send the steering signal to the mobile thing via radio.
Or use 2 transmitters and steerable antenna on the moving thing.,
Bit of luck and yuo could use local radio stations...
And at night use the stars.... :-) If it is not cloudy..
My camera modules are Sony super HADs, ultra low light ones....
 https://www.ebay.com/itm/166096040231?
analog video out, makes it very easy to process with with a Microchip PIC 18F14K22
but I grew up with analog video.....

There is  lot more to it..
These days with a simple Raspberry and a digital camara module in daylight object recognition is possible:
 https://core-electronics.com.au/guides/object-identify-raspberry-pi/
Have not triad that.
Seems fun :-)