1. CS 415 – A.I. Slide Set 10

2. Controlling Multiple Robots Different considerations for multiple robots – Inherently dynamic environment – Complex local and global interaction – Increased (Compounded) Uncertainty My uncertainty about myself My uncertainty about you Your uncertainty about yourself – Need for Coordination identity, intention, communication, plans Working as a “team” – Need for Communication

3. Team Work Coordination – arranging things in some kind of order Cooperation – joint actions with a mutual benefit Large area of active research – group robotics – social robotics – team robotics – swarm robotics – multi-robot systems

4. Benefits of Teamwork Some Tasks Require 2+ Robots – Transporting objects Construction/building Clearing barriers (disaster relief)‏ Moving wounded people Some Tasks are Better with 2+ – Cheaper, faster, more efficient Foraging – land mines, crops, laying cables Surveillance Mapping?

5. Benefits of Teamwork Robustness and Redundancy – Robustness – ability to resist failure – Redundancy – replication of abilities on the team Not all teams are redundant – Some teams are made up of specialist robots – Not very robust then

6. Challenges of Teamwork Interference → enemy number 1 – The more robots, the worse it is Physical Interference  1 robot undoes the work of another Communication Interference Uncertainty The more robots, the worse it is Compounding Expenses Always costlier for more hardware Always more to break down/not work

7. Types of Teams How program a team of robots to play soccer? – Everyone tries to get the ball and score Is this a good idea? – Instead Division of Labor Homogenous Teams – Pros? Cons? Heterogenous Teams – require active cooperation to get coordinated behaviour

8. Types of Teams Merely coexisting – Multiple robot with shared task – No communications or maybe even recognize one another – Treat each other as obstacles Loosely coupled – Recognize one another / simple coord. – Don't depend on one another Members of groups can be removed Precise tasks are hard to complete

9. Types of Teams Tightly Coupled – Focus on a precise task Use communication, turn-taking, etc. – Removing robots hurts performance

10. Communication Many times members of a team need to communicate information to each other – Improve perception – Synchronize actions – Enabling coord. and negotiation What get communicated – Task-related states – Individual states – Environment states – Goal(s)‏ – Intentions

11. The How of Communication Explicit Comm. → send a preformed message – Broadcast Comm. – P2P Comm. Publish-subscribe Comm. – Player/Stage Inherent cost to explicit comm.

12. The How of Communication Implicit Comm. → individual leaves info. In the environment – Stigmergy – comm. through intentionally changing the environment Ant trails Positive feedback → the stronger the “change” (i.e. pheromones) the more it happens

13. Kin Recognition Kin recognition – recognizing members of my team in a dynamic multi-faceted environment Kin recognition is no simpler than object recognition – Already know object recognition is hard Dominance Hierarchy – Who's in charge – How do you identify that robot?

14. Team Control Centralized Control – “I'm the boss” The boss doesn't even necessarily have to be a robot → not exactly autonomous control then – Cons? Pros? Distributed Control – No central store of information – Immanently scalable (add robots)‏ – Hard to plan for this kind of control

15. The Next Assignment Groups (again, 2-3 people)‏ Team Robotics Project – Do you use a map? – What kind of team organization? Anything but merely coexisting will be fine – What kind of control Totally up to you