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From: john larkin <JL@gct.com>
Newsgroups: sci.electronics.design
Subject: Re: IR detector system, biasing of photo diode
Date: Tue, 29 Oct 2024 07:45:48 -0700
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On Tue, 29 Oct 2024 00:49:00 +0100, Klaus Vestergaard Kragelund
<klauskvik@hotmail.com> wrote:

>On 28-10-2024 20:05, john larkin wrote:
>> On Mon, 28 Oct 2024 11:11:38 +0100, Klaus Vestergaard Kragelund
>> <klauskvik@hotmail.com> wrote:
>> 
>>> On 27-10-2024 18:56, john larkin wrote:
>>>> On Sun, 27 Oct 2024 09:03:20 GMT, Jan Panteltje <alien@comet.invalid>
>>>> wrote:
>>>>
>>>>> On a sunny day (Sun, 27 Oct 2024 02:19:14 +0200) it happened Klaus Vestergaard
>>>>> Kragelund <klauskvik@hotmail.com> wrote in <vfk0u0$3u9en$1@dont-email.me>:
>>>>>
>>>>>> Hi
>>>>>>
>>>>>> 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.
>>>>>>
>>>>>> I need it to be insensitive to ambient light/sunlight.
>>>>>
>>>>>
>>>>> I use a cheap camera module to track a light source in H and V direction, and just a simple Microchip PIC : for processing
>>>>> It can, with some added code, track object forms too, like a cross or maybe a big character.
>>>>> panteltje.nl/pub/horizontal_IR_target_tracking_4686.avi
>>>>> those camara modulea are IR sensitive to some extend, sometimes you can remove the IR filter from such modules.
>>>>> It may be a bit of overkill for your application, but OTOH it can do a lot more.
>>>>> Mainly designed to detect and follow jet exhaust..
>>>>> You could uee utrasonics too, maybe even simpler, no sun problem, like a bat.
>>>>> Cheap electret mikes? or modify some ebay 1 dolalr distance sensors...
>>>>> can be used for anti-collision too.
>>>>>
>>>>>
>>>>
>>>> Right. A sonic scheme could measure the phase between two mikes to
>>>> determine the direction of the source with high resolution. That could
>>>> be an analog multiplier or a bit of code. The amplitudes would be
>>>> useful too.
>>>>
>>>> One could compute direction, distance, and velocity almost for free.
>>>>
>>>> No problem with sunlight!
>>>>
>>> Could also be done with a chirp and auto-correlation, although this does
>>> not use the phase, but a beacon reference instead
>> 
>> Could that tell the direction of the mother ship?
>> 
>
>If the chirp arrives at the same time at each mike, the robot is on the 
>right path, If one is delayed, the robot eases into the that direction
>
>> Three or four omni mems microphones could tell the robot which
>> direction to go with full 360 degree coverage.
>> 
>> Maybe even estimate range.
>> 
>I did a design based on a rectangular wire loop, with 4 pickup coils in 
>a star formation. That configuration could tell the robot how much it 
>was off directly without using a search pattern.
>
>But, they do not want that, all though it performance very good.

Life would be so much better without customers.