[Dprglist] Fwd: PAA5100JE Near Optical Flow SPI Breakout is now available at Pimoroni!

[Kevin T. Shin]

Hi Murray,
I have been very interested in the optical flow sensors to detect the wheel slippage. I have used the old laser mouse, but certainly give this a try. Thank you. 

Kevin

Sent from my iPhone

> On Jun 9, 2021, at 3:53 AM, Murray Altheim via DPRGlist <dprglist at lists.dprg.org> wrote:
> 
> Hi Karim,
> 
> I'll be very interested in hearing how you and yours figure out the best way to
> use these new sensors. I think overall they'll be very helpful to those wanting
> some sort of optical odometry, or at least some kind of optical assist. As I
> mentioned, even if it can't be used for truly accurate odometry over varied
> surfaces it still might be very handy for driving in a straight line, or other
> tricks we haven't even thought of yet.
> 
> Cheers,
> 
> Murray
> 
>> On 9/06/21 9:34 am, Iron Reign wrote:
>> Thanks Murray. Very helpful. I've ordered a brace of them. They're not in the Amazon store yet, so gotta wait on international shipping.
>> On Tue, Jun 8, 2021 at 4:18 PM Murray Altheim via DPRGlist <dprglist at lists.dprg.org <mailto:dprglist at lists.dprg.org>> wrote:
>>    Hi Karim,
>>    I'll try to get the post, which is about half ready, posted ASAP, though I've
>>    got a lot going on right now at home and work.
>>    I think it's definitely worth a look. My initial play with it was using the
>>    existing PMW3901 Python library, as suggested by the Pimoroni techs, and I'd
>>    tested it out over nine different surfaces and with that library I found the
>>    image complexity was clearly related to the measured velocity, but Pimoroni
>>    updated their library, and while the update doesn't entirely eliminate that
>>    issue, it's much less significant than before. I don't think you'll be able
>>    to use the sensor solely to measure distance over significantly varied
>>    surfaces with accuracy, but over a relatively constant surface I think it's
>>    pretty good, within a few percent.
>>    It outputs a simple stream of x,y values when moving, clearly on an interrupt
>>    basis as that stream stops when the movement stops. I measured the 'x'
>>    dimension (oriented as it was) over one meter and so long as I stayed on the
>>    kind of surface that I calibrated it for the measurements were quite accurate.
>>    An interesting notion might be to use the other axis with a PID controller to
>>    travel in a straight line, as while dragging my little robot sled over the
>>    test surface I'd get small 'y' values that could be used for course correction.
>>    With the new Python library I think the minimum to maximum of the nine
>>    surfaces I tested on (tile, wood floor, lawn, concrete, rug, etc.) varied by
>>    something like 10-15%, but on any given surface the ten runs of my test
>>    varied by only a few percent max, often less than 1%. Repeatable results.
>>    It'd be possible to calibrate the sensor over different surfaces and switch
>>    calibrations based on the surface if it were possible to detect the surface
>>    type, possibly using a camera or spectrometer sensor like the Pimoroni
>>    AS7262 that could detect color (which actually works pretty well, e.g.,
>>    it's easy in my house to know the difference between my tile, wood and
>>    carpet flooring by color). I've got a spreadsheet of results that will be
>>    part of the review/blog post.
>>    At £18.90 (US$26.75 / NZ$37) it's not cheap but I think worth a look, yes.
>>    The only downside really, which was entirely predictable, is that its
>>    operating range is 10-35mm, suitable for hanging underneath a small robot,
>>    but not so much under say, a Mars rover, whose bottom is likely higher than
>>    35mm. In that case the PWM3901 would be more suitable, but not necessarily
>>    as accurate,
>>    Cheers,
>>    Murray
>>    On 9/06/21 8:52 am, Karim Virani wrote:
>>     > How about at least a teaser? Worth a look?
>>     >
>>     > On Tue, Jun 8, 2021 at 3:49 PM Murray Altheim via DPRGlist <dprglist at lists.dprg.org <mailto:dprglist at lists.dprg.org> <mailto:dprglist at lists.dprg.org <mailto:dprglist at lists.dprg.org>>> wrote:
>>     >
>>     >     Hi,
>>     >
>>     >     FYI, Pimoroni has finally announced stock availability on their new PAA5100JE
>>     >     Near Optical Flow Sensor, which I'll be posting a review on hopefully soon.
>>     >
>>     >         PAA5100JE Near Optical Flow SPI Breakout
>>     >         Detect motion of close-up surfaces with this Breakout Garden compatible
>>     >         optical navigation breakout - great for floor tracking for ground dwelling robots!
>>     > https://shop.pimoroni.com/products/paa5100je-optical-tracking-spi-breakout <https://shop.pimoroni.com/products/paa5100je-optical-tracking-spi-breakout> <https://shop.pimoroni.com/products/paa5100je-optical-tracking-spi-breakout
>>    <https://shop.pimoroni.com/products/paa5100je-optical-tracking-spi-breakout>>
>>    ...........................................................................
>>    Murray Altheim <murray18 at altheim dot com>                       = =  ===
>>    http://www.altheim.com/murray/ <http://www.altheim.com/murray/>                                     ===  ===
>>                                                                         = =  ===
>>          In the evening
>>          The rice leaves in the garden
>>          Rustle in the autumn wind
>>          That blows through my reed hut.
>>                 -- Minamoto no Tsunenobu
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> 
> -- 
> 
> ...........................................................................
> Murray Altheim <murray18 at altheim dot com>                       = =  ===
> http://www.altheim.com/murray/                                     ===  ===
>                                                                   = =  ===
>    In the evening
>    The rice leaves in the garden
>    Rustle in the autumn wind
>    That blows through my reed hut.
>           -- Minamoto no Tsunenobu
> 
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