CoMutaR : An approach for task allocation

1. Pedro Mitsuo Shiroma Advisors: Mario F. M. Campos Vijay Kumar CoMutaR: An approach for task allocation

2. Motivation In a near future it is very likely that several robots will be present in the same workspace

3. Motivation In this scenario we will have: • Robots executing its assigned tasks, • with rich sensorial capacity, • high processing power, • and communication devices; • A lot of underutilized resources; • Increasingly large amounts of continuously gathered data;

4. Motivation How to effectively allocate the available resources (whole robots, sensors, gathered data, actuators, processing power, etc.) for the successful execution of multiple tasks? or, more formally…

5. Problem definition Given a set of (possibly) heterogeneous mobile robots located in a dynamical environment and a set of tasks that need to be executed, allocate tasks to one or more robots as efficiently as possible.

6. robot1 Task1 robot2 Task2 Task3 robot3 Task4 ... ... robotm Taskp Problem definition

7. Outline • Related work • CoMutaR • Experimental results • Conclusion

8. Outline • Related work • CoMutaR • Experimental results • Conclusion

9. Related Work: Taxonomy • Tasks • Robots • Assignment [Gerkey 2003]

10. Related Work: Taxonomy – Tasks • SR – Single-Robot tasks • MR – Multi-Robot tasks robot1 Task1 robot2 Task2 robot3

11. Related Work: Taxonomy – Assignment • No knowledge • Model-based Task1 Task2 t t0 t1 Task1 t2 Task2 t

12. Related Work: Taxonomy – Robots • ST – Single-Task Robot • MT – Multi-Task Robot robot1 Task1 robot2 Task2 Task3

13. Related work

14. Related work “'Most commonly, task allocation problems assume robots are single-task robots, since more capable robots that perform multiple tasks in parallel are still beyond the current state of the art” Lynne E. Parker, Springer handbook of robotics (2008) “The MT-SR-IA and MT-SR-TA problems are currently uncommon, as they assume robots that can each concurrently execute multiple tasks. Today’s mobile robots are generally actuator-poor. Their ability to affect the environment is typically limited to changing position, so they can rarely execute more than one task at a time.” Gerkey & Mataric – Int. J. of Robotics Research (2004)

15. Outline • Related work • CoMutaR • Experimental results • Conclusion

16. CoMutaR: Coalition formation based on Multitasking Robots • MT-MR-IA; • Coalition of actions x schemas • Queries x information type • Share-restricted resources x

17. CoMutaR: Overview

18. CoMutaR: Overview • Assumptions • Tasks can be subdivided into actions; • Actions are able to determine or estimate, based on the query, its constraint functions; • If all inputs (queries) and constraint functions are not broken then the action will successfully perform as expected.

19. CoMutaR: Nomenclature robot • : the 4th action in robot 3; • : the 2nd share-restricted resource in robot 1 • : the constraint function imposed by over action Share-restricted resource

20. CoMutaR • Overview • Action • Coalition • Query • Share-restricted resource

21. action2 robot1 action1 action3 CoMutaR: Action • An action is any computational module that can either produce data or perform a task robot1 Task1

22. CoMutaR: Action • Sensor reading: • Data transform: • Task accomplishing: actioni actioni actioni Task

23. CoMutaR • Overview • Action • Coalition • Query • Share-restricted resource

24. CoMutaR: Coalition • Coalition is a temporary organization of actions that are brought together to tackle a particular task obstacle detector laser obstacle avoider Obstacle avoidance obs range

25. open auction open query open query cost cost bid winner connect CoMutaR: Bidding protocol • Coalition formation • Protocol (IA) Obstacle avoidance obstacle avoider obstacle detector laser obs range sonar range Obstacle avoidance obstacle avoider obstacle detector laser sonar t connect

26. CoMutaR • Overview • Action • Coalition • Query • Share-restricted resource

27. CoMutaR: Query • Information type [Donald1997]: • Resource database [Cowley2004]: • Query: obstacle detector laser range

28. CoMutaR: Query • Dynamical environments: • Reactive tasks: • Mapping: • User interface:

29. data importer obstacle detector Laser data exporter obs range robotj CoMutaR: Query obstacle avoider obstacle detector Laser Obstacle avoidance range obs roboti

30. CoMutaR: Query • An action can execute only if all input queries are answerable; • A query is a contract between producer and consumer, which guarantee data connection; • A query can include other queries: • A surveillance action is taking snapshots: • A pursue action in the same robot is trying to track an intruder:

31. CoMutaR: Query • An action can intervene on the query of another action: • An obstacle avoidance is querying for obstacles: • A box pushing action can alter the region queried by the obstacle avoidance:

32. CoMutaR • Overview • Action • Coalition • Query • Share-restricted resource

33. CoMutaR: Share-restricted resource • MT (Multitasking) robots Task1 robot1 Task2

34. CoMutaR: Share-restricted resource • A share-restricted resource is any property that belongs to a robot and cannot be freely shared among actions. • Communication link; • Processing power; • Pose; • Power consumption; • A share-restricted resource is any property that belongs to a robot and cannot be freely shared among actions. • Communication link; • Processing power; • Pose; • Power consumption;

35. CoMutaR: Share-restricted resource – Pose • Configuration space composition surveillance controller

36. CoMutaR: Share-restricted resource – Pose • Constraints imposed by sensors compound Planned task for another action Region to be sensored

37. action1,2 ... CoMutaR: Share-restricted resource – Constraint function ... action1,1 ... ... ... . . . ... actioni,n ...

38. CoMutaR: Share-restricted resource – Constraint function • Codomain; • Constraint function: • Maximum capacity: • compound operator: • comparison operator:

39. CoMutaR: Share-restricted resource – Communication link • codomain: • : required communication bandwidth • : maximum bandwidth • 30Mb/s + 20Mb/s ≤ 100Mb/s

40. CoMutaR: Share-restricted resource – Processing power • codomain: • : required processing time • : allocated processing power • 10Mhz + 20Mhz ≤ 100Mhz

41. CoMutaR: Share-restricted resource – Pose • Configuration space Obstacle avoider Non-holonomic constraint composition

42. CoMutaR: Share-restricted resource – Pose • Constraints imposed by sensors (queries) Queries are periodically updated

43. Potential field CoMutaR: Share-restricted resource – Pose • Scenario

44. CoMutaR: Share-restricted resource – Position • codomain: • : empty space

45. CoMutaR: Coalition formation based on Multitasking Robots action2 action1 Task1 db1 db2 actionn

46. Outline • Related work • CoMutaR • Experimental results • Conclusion

47. Tightly-coupled tasks – Box pushing • Vleft • vright

48. Trajectory Tightly-coupled tasks – Box pushing • Scenario

49. Tightly-coupled tasks – Box pushing • Active actions

50. Loosely-coupled tasks – Surveillance and Transportation N = 8 N = 2 N = 16