Subject: VR mechanical animation

From: [email-masked] (Lance Norskog)
Date: Fri, 21 Feb 92 08:51:57 PST

Rodney Brooks of MIT gave two lectures at Stanford this week.
His AI robot group uses a very different philosophy about AI
than standard approaches.  His stuff is intended to work in
real-time with very low processing requirements.  I think his
techniques can be use to build interesting reactive & moving
robots in virtual worlds.

He showed how his robot control systems work.  They're just dataflow
networks of nodes, where each node is a finite state machine with a
little control logic around it.  His example 6-legged walking insect
had 9 boxes (most standing for 6 copies of an FSM) and walked OK.  He
added 6 more boxes in 3 stages, creating better locomotion over
obstacles with each addition.

The 6-legged walker used feedback loops.  A robot that hunts for
an empty soda can and carts it off had many more boxes, but
no feedback loops at all.  Low-level things like "move the wheels"
would go out, and higher-level things watch these and countermand
them.  The motor control buses are lines of countermand boxes with
higher&higher-level behaviors later in the chain overruling lower-level
commanders.  A higher-level commander can decide when to overrule.
(This no-feedback method yields a completely planar circuit
which makes VLSI compilation much simpler.)

I can add this stuff to my VR system easily, and have walking
machines & reactive systems that run with little CPU overhead.
One of his students said there's a book by John Connell of
MIT (MIT Press perhaps?) explaining the schema and design
methods.  Brooks' group has a compiler that creates the
FSM networks from higher-level descriptions; I don't know if
he'll be willing to liberate it.  

BTW: my VR system actually does stuff now.  Mouse inputs
can be fed to points that form sides of boxes.

Lance Norskog
[email-masked]

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From: Dave Stampe-Psy+Eng <dstamp@watserv1>
Date: Fri, 21 Feb 92 18:09:30 -0500

Problem with doing this kind of stuff for VR:  it's not needed at all.  
These devices are built to react to the real (unknown) world, and
you have a very good world model in the VR system.  On the other hand,
a simplified version of the FSM based on surface contact and joint angles
would result in automatic motion.  On a flat surface, a sequence table
would work just as well.  Finally, you wouldn't need to add balance or
loading/force feedback unless you wanted the ultimate in slow but
lifelike actions.

BTW, we've just about got a select/move mouse interface done, and are
starting in on the armature motion soon.

- Dave Stampe