jlc@lifia.imag.fr (Jim Crowley) (05/18/91)
I also did not see the original post, but this is a topic which is important to the work of my group. Real Time: I define "real time" to mean providing a result within a fixed delay. We form our systems as a layered set of servo loops, each working in a more abstract "space". (Unlike NASREM, we allow loops at teh same level to communicate). (See "Coordinating Action and Perception in a Surveillance Robot" in IJCAI 87 or in IEEE Expert, Winter 87. ) I take AI to mean "symbolic reasoning". Such techniques sit just above our algorithmic "actions" and are also organised as a servo loops. Symbolic Reasoning systems are notoriosly slow; Worse it is difficult or impossible to predict the cycle time. The solution is to let the symbolic reasoning system operate as a separate process. Under UNIX and VRTX this process communicates with other processes by sockets. Memory: The other half of the problem is that most real time systems have limited memory, while most symbolic reasoning systems run on LISP. Many LISP's are notoriuosly BIG. For years we have used OPS5 to build our supervisors. We have been using Dan Miranker's (U Texas) C based ops5. This allowed us to squeeze the MITHRA Mobile RObot supervisor onto a 2 megabyte memory on a dedicated 68020. > Seems to me that one could do everything in 'C' by using CLIPS [C Language > Integrated Production System]..... We obtained a copy of CLIPS a few weeks ago. It's GREAT! Its integration into a C based system seems direct. It also fixes a number of complaints about ops. And, the keywords are more natural. We are likely to do all future real time symbolic control work in clips. James L. Crowley, LIFIA (IMAG), I. N. P. Grenoble -- ------------------------------------------------------------------------ James L. Crowley LIFIA (IMAG), 46 av. Felix Viallet, 38031 Grenoble FRANCE tel: (33) 76 57 46 55 -- fax : 76 57 46 02 email : jlc@lifia.imag.fr ------------------------------------------------------------------------