[Robotgroup] more about motor controllers

[Paul Atkinson]

I've flown radio controlled aircraft in the past and there is usually tight
control over frequencies at organized events. They do it by requiring that
you clip your model insurance card to the frequency pin board before you fly
or by impounding all the transmitters and only releasing your one when
absolutely necessary. Obviously there isn't such tight control at an open
even like Maker Faire (but it is enforced at all flying events, Top Gun,
etc.)

As far as detecting a jammed frequency, it would be next to impossible to
determine which was the valid signal and which was the rogue on the same
frequency. Gray's suggestion of never using full stick deflection might
work, but losing control of a robot at slow speed is still losing control.

On Vern's suggestion of a foot safe bumper switch; it's probably the best we
can do. Be careful you don't use it to remove power from a part of the robot
that needs power to support itself. One of my college robots (stationary arm
on a table) had a safety cord going around the perimeter of the table. The
idea was if the arm got in trouble, anyone could pull the safety and stop it
- like the wire you pull to request a bus stop. The bad part is that the
wire cut all the power and turned the arm into dead weight, converted
potential energy into kinetic, and darn near broke the table in two the
first time it was used. Fortunately there were no body parts under the arm
at this point!

(It was later adjusted to stop any moving parts and maintain any stationary
joints!)

Paul

On Mon, Apr 28, 2008 at 12:30 PM, Vern Graner <vern at txis.com> wrote:

> Gray Mack wrote:
> > A secondary safety switch a good idea for big bots.
>
> I've been contemplating a "bump switch" ring around the boogie bot..
> like a hula hoop or maybe some "pool noodles" on a wire frame. The idea
> being to cut power to motors in the event of impact with an object..
> like a shin... ;)
>
> Vern
>
> --
> Vern Graner CNE/CNA/SSE    | "If the network is down, then you're
> Senior Systems Engineer    | obviously incompetent so why are we
> Texas Information Services | paying you? Of course, if the network
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> Austin Office 512 328-8947 | you, so why are we paying you?" (c)VLG
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