1. FEUP AsasF– Unmanned Air Vehicles Project Group Developing of a Softwall Controller to avoid No-Fly-Zones in an existing Autopilot System Christoph Bruno Ruetz Departamento Engenharia Electrotécnica e Computadores Faculdade de Engenharia da Universidade do Porto R. Dr. Roberto Frias, 4200 465 Porto, Portugal E-mail: cruetz@gmx.decruetz@gmx.de

2. 2 AsasF– Unmanned Air Vehicles Project Group FEUP Structure n Motivation n Apollo System n Softwall System Goals Requirements n Approaches n Implemented System Goals Software structure Problems n Future Developments

3. 3 AsasF– Unmanned Air Vehicles Project Group FEUP Motivation n After 9/11, more than ever safety in and around air vehicles is needed n Ever since, several ideas appeared: to forecast if a plane will fly into a building to prevent a pilot from flying into a building n Control Commands should not be directly sent to the airplane steering to design a System, it has to be between the control and steering

4. 4 AsasF– Unmanned Air Vehicles Project Group FEUP Apollo System n UAV controller component of the AsasF control hierarchy, developed in FEUP n Decouples details of UAV control from organization of external controllers

5. 5 AsasF– Unmanned Air Vehicles Project Group FEUP Softwall System [Goals] n Define a system that avoids detected Softwalls n The System should be a part of Apollo  Modularity n But anyway there should be a possibility to decide whether the module will be used or not

6. 6 AsasF– Unmanned Air Vehicles Project Group FEUP Softwall System [Requirements / Environment] n Language was C++, because Apollo is written in C++ n modularity  good planning of Object structure n SVN for developing both projects (Apollo and Softwall) at the same time n Defining softwalls n Algorithms that meet requirements to detect and avoid softwalls

7. 7 AsasF– Unmanned Air Vehicles Project Group FEUP Approaches (I) n Reachability Sets from Ian Mitchell [1] Backward calculation from a obstacle from where it‘s possible to reach it heavy calculations Existing matlab sources but no c++  giving up this approach

8. 8 AsasF– Unmanned Air Vehicles Project Group FEUP Approaches (II) n 2D-Softwall graphical approach from J. Adam Cataldo [2] Base: Critical measurement 1/T  Depends on the direction, the distance and the max turning rate of the airplane  Safe!!! Tested in a Research Project [3]

9. 9 AsasF– Unmanned Air Vehicles Project Group FEUP Approaches (III) n Using Airplane Model  s := speed; := heading; t := time; p := position

10. 10 AsasF– Unmanned Air Vehicles Project Group FEUP Approaches (IV) n How does it work…? No-Fly-Zone radius collisionAvoid window Waypoint collision

11. 11 AsasF– Unmanned Air Vehicles Project Group FEUP Approaches (V) n Checking the critical time every 100 ms n In an avoiding window… the pilot will be informed about a potential collision starts at 4th and ends at 6th times of the min turn radius n If missing, evasive action with the max. turn rate initiates n After a certain time the airplane tries to follow the old plan n Checking begins again  Like a POTENTIAL FIELD ALGORITHM

12. 12 AsasF– Unmanned Air Vehicles Project Group FEUP Approaches (VI) n This approach is the basis of the Avoiding system  Problems: Calculation only during the flight not smoothed enough  Solution: pre-calculation of a possible trajectory as a second algorithm set upon the first algorithm  Trajectory calculation is needed A lot of different kind of algorithms from Industrial robot sector, like… Roadmaps (Voronoi, Visibility Graphs, Decomposition…) (just good for 2D Environments  A* (discretize the C-Space)  PRMs (unpredictable)  …  Baginsky algorithm

13. 13 AsasF– Unmanned Air Vehicles Project Group FEUP Approaches (VII) n Why Baginsky? Geometrical Approach from Boris Baginsky Heuristic Short search time in low dimension <= 3D Good path quality Good solutions in 2D or 3D environments n How does it work…?

14. 14 AsasF– Unmanned Air Vehicles Project Group FEUP No-Fly-Zone radius Waypoint

15. 15 AsasF– Unmanned Air Vehicles Project Group FEUP No-Fly-Zone radius Waypoint

16. 16 AsasF– Unmanned Air Vehicles Project Group FEUP No-Fly-Zone radius Waypoint Deepest intrusion point

17. 17 AsasF– Unmanned Air Vehicles Project Group FEUP No-Fly-Zone radius Waypoint Deepest intrusion point Middlepoint to move

18. 18 AsasF– Unmanned Air Vehicles Project Group FEUP No-Fly-Zone radius Waypoint Middlepoint to move Moving t-times Collision

19. 19 AsasF– Unmanned Air Vehicles Project Group FEUP No-Fly-Zone radius Waypoint Middlepoint to move Moving t-times No Collision Collision

20. 20 AsasF– Unmanned Air Vehicles Project Group FEUP No-Fly-Zone radius Waypoint Middlepoint to move Moving t-times No Collision Collision

21. 21 AsasF– Unmanned Air Vehicles Project Group FEUP No-Fly-Zone radius Waypoint Middlepoint to move Moving t-times No Collision Collision

22. 22 AsasF– Unmanned Air Vehicles Project Group FEUP No-Fly-Zone radius Waypoint Middlepoint to move Moving t-times No Collision Collision

23. 23 AsasF– Unmanned Air Vehicles Project Group FEUP No-Fly-Zone radius Waypoint Middlepoint to move Moving t-times No Collision Collision

24. 24 AsasF– Unmanned Air Vehicles Project Group FEUP No-Fly-Zone radius Waypoint Middlepoint to move Moving t-times No Collision Collision

25. 25 AsasF– Unmanned Air Vehicles Project Group FEUP No-Fly-Zone radius Waypoint Middlepoint to move Moving t-times No Collision Collision

26. 26 AsasF– Unmanned Air Vehicles Project Group FEUP No-Fly-Zone radius Waypoint Moving t-times No Collision Collision

27. 27 AsasF– Unmanned Air Vehicles Project Group FEUP No-Fly-Zone radius Waypoint Moving t-times No Collision

28. 28 AsasF– Unmanned Air Vehicles Project Group FEUP Implemented System [Goals] n Apollo decides if the Softwall System will be in use Just activate the module in Apollo or not n Apollo and Softwalls should have access to the same information of the Airplanes n Softwalls and Apollo should work as a module of its own. Adapter Classes docking on the module to communicate with the environment  That will guarantee independence by changing Autopilot Systems

29. 29 AsasF– Unmanned Air Vehicles Project Group FEUP Implemented System [Architecture] 2D-Approach Baginsky Generic Autopilot Interface Softwall Filter System Apollo Pathplanner CollisionManager Airplane Softwall Config File

30. 30 AsasF– Unmanned Air Vehicles Project Group FEUP Implemented System [Software] n Define softwall Neptus - Config file - SoftwallS [Circle 1] alt = 100;altidude in meters lon = 0.6565;longitude in radians lat = -2.1342;latitidue in radians radius = 100;in meters if should be a circle [Halfspace 1] alt = 100;altidude in meters lon = 0.6565;longitude in radians lat = -2.1342;latitidue in radians heading = 3.159;in radians, defines the direction of the ;halfspace if it‘s a halfspace

31. 31 AsasF– Unmanned Air Vehicles Project Group FEUP Implemented System [Problems] n Reachabillity Sets not practicable  2D Approach n Apollo modularity was changed n Execution of Apollo had to be stopped if the airplane was following a trajectory

32. 32 AsasF– Unmanned Air Vehicles Project Group FEUP Future developments n Reachability sets translate in C++ code n 3D Softwalls calculation n Define airplanes as moving softwalls  currently there are only static softwalls n Implement softwalls in other Vehicles n Safety and a real environment should be tested n Testing intersection Halfspaces n Make the plane follow a softwall n Send all calculated points at the same time

33. FEUP AsasF– Unmanned Air Vehicles Project Group Developing of a Softwall Controller to avoid No-Fly-Zone in an existing Autopilot System Christoph Bruno Ruetz Departamento Engenharia Electrotécnica e Computadores Faculdade de Engenharia da Universidade do Porto R. Dr. Roberto Frias, 4200 465 Porto, Portugal E-mail: cruetz@gmx.decruetz@gmx.de Obrigado!

34. 34 AsasF– Unmanned Air Vehicles Project Group FEUP Sources n [1] Ian Mitchell, APPLICATION OF LEVEL SET METHODS TO CONTROL AND REACHABILITY PROBLEMS IN CONTINUOUS AND HYBRID SYSTEMS, 2002, Berkeley n [2] J. Adam Cataldo, Preliminary Version of a Two- Dimensional Technical Specification for SoftWalls, 2002, Berkeley n [3] Boris Baginsky, Motion Planning for Manipulators with Many Degrees of Freedom – The BB-Method, 1999, TU Munich

35. 35 AsasF– Unmanned Air Vehicles Project Group FEUP Implemented Systems [Messages] n Error/message Handling kindmascdetect WP creation failederrwaypoint=trueCreating WP Manouvre couldn‘t createerrmaneuvre=trueAfter creating WP Avoiding failederravoiding = trueDuring avoiding Avoiding in operationmsgstartav=true msgstopav=false After creating manouvre Finished avoidingmsgstopav=true msgstartav=false After avoiding

36. 36 AsasF– Unmanned Air Vehicles Project Group FEUP

37. 37 AsasF– Unmanned Air Vehicles Project Group FEUP

38. 38 AsasF– Unmanned Air Vehicles Project Group FEUP

39. 39 AsasF– Unmanned Air Vehicles Project Group FEUP