[Dprglist] self driving trucks and the desert

[Rud Merriam]

I don't recall the details of what makes David's subsumption unique. In 
my first NASA competition I used subsumption with a unique twist. There 
was a behavior that would switch the subsumption list being used.

If you're not familiar with subsumption is is a list of behaviors or 
actions. Every cycle the list begins again until one of the behaviors 
"fires". The processing starts again at the beginning of the list. 
That's simplified but gives the idea. I actually found that setting a 
flag and letting the list finish processing also worked. Once the flag 
was any following behavior would not "fire" but it could record 
information. That was useful for handling behaviors that did a timing 
function.

Since then I've moved to behavior trees (BT) which are used in robotics 
and for autonomous actors in games. That shooter coming after you is 
driven by a BT. Subsumption is actually subsumed (ha!) by BTs as one of 
the techniques used in the trees.

Subsumption is basically an OR operation, just like a logic gate. If one 
behavior fires the overall  gate becomes true and returns to a higher 
level in the tree. There is also an AND operation where all the 
behaviors must fire before returning true. If one fails to fire a false 
is returned. The other main operation is NOT which is an inverter of the 
output of a list.

There is a lot written about BTs but not as logic gates as I've 
described them. I have code which does this but need to update it for 
C++20. Once I complete that revision I want to look at learning using 
BTs, i.e. adding new behaviors including expanding the trees. An 
advantage of treating them as logic gates is boolean algebra is 
applicable which allows simplifying trees using some well known 
techniques. After learning a larger tree can be trimmed to a more 
compact but logically equivalent representation.



-73 -
*Rud Merriam K5RUD*
/Mystic Lake Software/ <http://mysticlakesoftware.com/>


> Thanks for the reply.  I think that perhaps part of the reality is 
> that I have developed a subsumption based reactive navigation method 
> that I believe is fairly unique --- the only other people I've 
> encountered that do the same have learned it from me. 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.dprg.org/pipermail/dprglist-dprg.org/attachments/20211027/bbb20969/attachment.html>