[Dprglist] Compass heading using gyroscopes?

[Murray Altheim]

Hi David,

This seemed timely as I was just putting in an order to Mouser for
a replacement Adafruit 240x240 TFT display (as Adafruit is still
discouraging ordering from them directly). While rewiring the
existing one over the weekend I somehow managed to somehow burn it
out. Grr. I broke a few things this weekend. Sometimes things go
awry [can you say "tits up" on a public forum?].

I'd originally thought my existing VL53L1X ToF sensor might be able
to locate a gap at 8' (2.44m) but forgot that its field of view is
27°. So no minding the gap there.

My other thought on alignment was to use one of those TFMini wannabe
LiDARs with an "ideal" range of 12m and a 2.3° "signal acceptance
angle" (which may be the same thing as field of view, dunno). But
2.3° at 8 feet is about 4 inches, which almost seems good enough.

The TFMini is around NZ$80-90 and sucks up 800mA of juice, so it
wasn't my first choice. By comparison, the chunky Sharp GP2Y0A710K0F
IR sensor ranges up to 5m, uses only 30mA and is about 2/3 the price.
They don't mention in the specs its field of view but sure it's
pretty wide. For a different purpose, understood. And the TFMini
isn't actually a real LiDAR anyway, just a lens-focused LED. pffft

I like the laser pointer idea better.

I looked and the only laser pointers on Mouser's website are the
industrial ones (Class 3), the kind that burn holes through whatever
you're pointing them at -- I could tattoo my cat at 20 feet. I found
a more suitable one on the NZ equivalent of eBay (TradeMe) that is
meant to mount on top of a gun (of course). In the advertisement it
states:

  "Plus, you'll be hitting meaningful targets, like bears and ducks
   and manly things, as opposed to the pretty little flowers that
   just happened to be in the way of your poorly aimed shot."

I'm not sure what a meaningful target is, except that there are no
bears in New Zealand so the guy is plainly either out-of-country or
out-of-his-mind. But this seems like the right model, runs on three
AG10 batteries, so either 3.3V or 5V probably would be fine, and it
comes in tactical black. Very cool and menacing.

This is *iff* I decide to partake in these silly contests. [he says
as he pulls out his credit card...]

On 18/05/20 12:00 pm, David Anderson via DPRGlist wrote:
> Murray,
> 
> Your comment is spot on.  On my SR04 robot there is a calibrated 
> laser pointer for that very purpose; pointing the robot accurately
> at the first target.   For the experiments with the RCAT robot,
> the robot itself uses it's sonars to do the alignment, but since
> in the demo video there are no other waypoints, it's hard to know
> how effective it is.
> 
> cheers
> 
> dpa
...........................................................................
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