[Robotgroup] Drive a Droid proposal... How to detect the "fence"?

[Clendon Gibson]

We need a fence. The point was that it could be a fence imposed by software. 

Many of the other fences are simply software detecting a state and preventing the robot from continuing. This isn't really different then the dead reckoning except that there is a physical thing representing a fence.With the dead reckoning you can still rope off an area, it's just that the robot does not use these for its fence detection. 

Given the size and speed of the thing, lay some sand filled PVC pipe.



----- Original Message ----
From: Vern Graner <vern at txis.com>
To: The Robot Group Mailing List <robotgroup at puremagic.com>
Sent: Tuesday, July 8, 2008 3:32:07 PM
Subject: Re: [Robotgroup] Drive a Droid proposal... How to detect the "fence"?

Clendon Gibson wrote:
> If you are good with geometry, then you can put encoders on
> the wheels and calculate your position by dead reckoning.

Friction errors accumulate as the wheels move over the surface and slide 
on occasion. You would have to rely on external, calibrations and 
corrections for any deviation caused by accumulated error. The amount of 
calibrations would depend on the surface, the wheels and the number of 
events that could cause slip (i.e. hard starts and stops, turns etc).

> The most obvious advantage is that there is no physical fence.

But we *need* a fence, if not for keeping the bot in, then to keep the 
audience from encroaching on the area the droid travels. We don't want 
to run over any toes. :)

Vern

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