[Dprglist] Compass heading using gyroscopes?

[Doug Paradis]

Murray,
    John's points are very valid. You can get a feel for the accuracy
needed on an indoor robot by marking a point on your robot and the floor of
your test space. Travel a square that is 375 cm (~12 ft) on side, with a
total travel distance of 1500 cm (48 ft), and mark where your robot ends on
the floor using the mark on the robot, and measure the distance it is off.
This is a short description of a DPRG Four Corner contest (see:
https://www.dprg.org/wp-content/uploads/2018/09/four_corners-201804303.pdf).
Typical performance a winning robot is sub - 12 mm, the 2nd and 3rd place
robots sub - 75.mm. Often in the past only encoders were used for
navigation (i.e., no gyro).Now usually a gyro is used for heading. Several
years ago John S. used a unique sonic trilateration system to achieve a
17.5 mm error, at the time a club record. Similar competitions by other
clubs have about the same outcomes.

Regards,
Doug P.

On Fri, May 15, 2020 at 4:36 AM Murray Altheim via DPRGlist <
dprglist at lists.dprg.org> wrote:

> Hi John,
>
> A one degree error may be two inches after ten feet, but I'll be reading
> that heading continuously so over that ten feet wouldn't things tend to
> balance out?
>
> I don't disagree but I think you may be missing my ultimate point: that
> even with low accuracy a robot will still have "a behaviour" and that is
> plenty good enough for my purposes, which are not competitive but rather
> the exploration of an indoor environment using a Behaviour-Based System,
> basically following along the research path set by Rodney Brooks et al.
>
> I am aware of the difference between resolution and accuracy, and having
> both a higher resolution and a higher accuracy would improve the robot's
> ability to navigate accurately -- certainly -- and I'm hardly against
> that; it's just that I'll be satisfied with much less. As I described
> previously, something akin to a determining which point on a 16 or 32-
> point compass rose is fine. If I can get better accuracy I might explore
> navigating according to a bearing but I have no requirement for that at
> this point. Maybe in the future... it's an interesting journey either way.
>
> Cheers,
>
> Murray
>
> On 15/05/20 8:00 pm, John Swindle via DPRGlist wrote:
> > A quick note: A one-degree error is two inches after ten feet. Not
> > good enough for small robot navigation unless something is constantly
> > providing better pointing accuracy. Even for the contests, if the robot
> > depends on that amount of error, it would miss the goal in 6 Can, might
> > hit the cone in Square Dance, etc. Outdoors, the accuracy has to be a
> > lot better. I think you will be very unhappy with 11.25 degree
> > resolution. And be careful that resolution and accuracy are not the
> > same thing.
> >
> > Later,
> > John Swindle
> ...........................................................................
> Murray Altheim <murray18 at altheim dot com>                       = =  ===
> http://www.altheim.com/murray/                                     ===
> ===
>                                                                     = =
> ===
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>             -- Minamoto no Tsunenobu
>
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