[Dprglist] Fwd: PAA5100JE Near Optical Flow SPI Breakout is now available at Pimoroni!
Iron Reign
ironreignrobotics at gmail.com
Tue Jun 8 16:54:17 PDT 2021
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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