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

Iron Reign ironreignrobotics at gmail.com
Tue Jun 8 14:34:31 PDT 2021

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> 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>> 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
> >
> ...........................................................................
> 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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