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

[Iron Reign]

It might be a better fit for the team since they run on a fairly uniform
surface. Too late for this season - State Championship is next week and
there's nothing beyond that since Worlds was cancelled. But it should make
a good summer project.

I wasn't necessarily thinking it would be great for outdoor robots with
much more varied terrain.  But we'll try that out too. It might be a good
additional way to detect and compensate for wheel slippage.

On Tue, Jun 8, 2021 at 6:25 PM Murray Altheim <murray18 at altheim.com> 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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