Alt-BEAM Archive
Message #04854
To: beam@sgiblab.sgi.com
From: Bruce Robinson Bruce_Robinson@bc.sympatico.ca
Date: Thu, 24 Jun 1999 17:36:34 -0700
Subject: [alt-beam] Re: Ah! Blessed Skepticism! (was: Feedback explained?)
Wilf Rigter wrote:
> To a standard suspended Bicore add a BG micro motor directly to the
> Bicore outputs. Observe the rotation and Bicore pulsewidth is about 90
> degree each way and 1 second pulsewidth duration. Now load the output
> shaft with some finger pressure (not a complete stall) ...
>
> If the Bicore output is buffered before connecting to the motor, the
> output pulse duration is actually slightly longer when the motor is
> loaded even if a small resistor is introduced in series with the
> powersupply to reduce supply voltage under load (so much for powersupply
> feedback)...
You know, Wilf, after thinking about this a bit, I infer a small
experimental flaw. Ben's comments set me on the right track, and I did
some theoretical calculations for various stalling conditions.
Theory suggests that a generally restrained robot (e.g. it's caught in a
pool of molasses) will not experience a shortened Nv cycle due to
voltage drawdown.
The most pronounced effect OUGHT to occur when the leg gets seriously
stuck half way through it's movement cycle. Experimentally, this would
involve applying a major load half way through the time delay.
Are you SURE you really want to get into this ?
Regards,
Bruce
------------------------------------------------------------------------
eGroups.com home: http://www.egroups.com/group/alt-beam
http://www.egroups.com
- Simplifying group communications
Home