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[DPRG] Robot Code
Subject: [DPRG] Robot Code
From: David P. Anderson
dpa at io.isem.smu.edu
Date: Fri Mar 16 18:39:59 CDT 2007
Hi Randy,
Thanks for the feedback and kind words.
Randy wrote:
<snip>
> > Two attributes of ballistic behaviors that may not be
> > immediately apparent:
> >
> > 1. Ballistic behaviors cannot be subsumed: the must run to
> > completion.
> >
> > 2. Ballistic behaviors can , however, be aborted.
>
> However, the above comments on ballistic behaviors breaking the
> subsumption paradigm, is purely dpa, and I can find no support
> for it in Jones or Brooks. (Which is not to say exactly I
> disagree with dpa either!)
I'm pleased you agree and flattered to think this is my
contribution alone, but alas I can't take credit.
The highest and lowest priority behaviors in a subsumption scheme
are asymmertical in the subsumption paradigm. The lowest priority
flag is always active, and the highest priority task is never
subsumed. All other tasks are both subsuming and subsumable,
but the highest and lowest priority task are not. They are
the boundary conditions, as it were.
The published and practical instances of subsumption that I have
been able to come across, that include a ballastic behavior, always
assign it the highest priority.
So it is by definition, never subsumed. I think if you look carefully
through the available literature you will find this is the case.
Hence subsumption of a ballastic behavior is a problem they never
confront, and probably the reason you've been unable to find an
explicit reference to it one way or the other.
I would be quite interested if anyone has a reference in published
literature or practical example of a ballastic behavior that
is subsumed by another behavior, and how it is accomplished.
best regards,
dpa
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