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, Porto, Portugal

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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 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 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 = ;longitude in radians lat = ;latitidue in radians radius = 100;in meters if should be a circle [Halfspace 1] alt = 100;altidude in meters lon = ;longitude in radians lat = ;latitidue in radians heading = 3.159;in radians, defines the direction of the ;halfspace if it‘s a halfspace

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 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

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, Porto, Portugal Obrigado!

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 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 AsasF– Unmanned Air Vehicles Project Group FEUP

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39 AsasF– Unmanned Air Vehicles Project Group FEUP