Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz                                               ...
Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz                                               ...
Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz                                       Technisc...
Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz                                    Technische ...
Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz                                      Technisch...
Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz                                         Techni...
Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz                                     Technische...
Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz                                      Technisch...
Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz                                   Technische U...
Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz                                     Technische...
Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz                                      Technisch...
Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz                                       Technisc...
Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz                                      Technisch...
Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz                                    Technische ...
Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz                                      Technisch...
Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz                                     Technische...
Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz                                     Technische...
Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz                                   Technische U...
Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz                                    Technische ...
Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz                                     Technische...
Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz                                              T...
Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz                                      Technisch...
Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz                                               ...
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Distributed Networks within ROS: Challenges and Possibilities

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Distributed Networks within ROS: Challenges and Possibilities

  1. 1. Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz Technische Universität München Distributed Networks within ROS: Challenges and possibilities Luis Roalter Technische Universität München, Germany
  2. 2. Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz Technische Universität MünchenAbout Studied 2004 Electrical Engineering and Information Technology Technische Universität München Starting PhD thesis 2009 Technische Universität München Research Topics: •  Intelligent Systems, esp. for home-automation •  Systems for homecare •  Wireless Sensor Systems and Smartphones •  Human-Computer Interfaces20.09.2012 Luis Roalter 2
  3. 3. Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz Technische Universität MünchenChallenges•  Large Intelligent Environments will have a substantial number of devices•  Integration of sophisticated robots into Intelligent Environments•  Make use of the “Internet of Things” within Intelligent environment•  Transition to modern IPv6 protocol stack to be prepared for future networks•  Make use of a distributed master-network•  Security concerns in large networks20.09.2012 Luis Roalter 3
  4. 4. Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz Technische Universität MünchenProblems to Solve:•  Internet of Things (which could be a robot as well) commonly depends on IPv6, so ROS needs to be able to speak IPv6•  Large environment are equipped with a huge number of sensors. A central ROS master would be inappropriate•  Communication has to work over borders of networks (Routers or different radios). Creating bridges between networks will increase the number of use-cases•  Internet of Things and Embedded systems have lower power. Decrease the size of the core-system and ease the configuration (low-weight nodes)•  A large number of nodes can lead to namespace-collisions. Usage of clear naming rules have to be established20.09.2012 Luis Roalter 4
  5. 5. Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz Technische Universität MünchenThe IPv6 protocol•  Expands the IP address range•  Easier routing techniques possible within IPv6•  Uses 128 bits for single addresses•  Always get the same address within a network•  Coding host-specific parts into the address (features, device-id, …)20.09.2012 Luis Roalter 5
  6. 6. Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz Technische Universität MünchenIPv6-Ideas for ROS•  Code the current location of the device inside the IP•  Directly connect to devices from the Internet of Things –  In short: with a local proxy master (gateway to devices) –  In long: Full multimaster capability inside the client libraries•  Communicate directly over network borders –  No more NAT in the way –  Smartphones with IPv6 connection can become part of the network from any place –  Problem: security concerns (when accessible from everywhere)20.09.2012 Luis Roalter 6
  7. 7. Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz Technische Universität MünchenMultimaster Capabilities•  Local masters reduce latency and CPU load•  Multiple masters increase the reliability of the whole network•  Robots with on-board master would integrate easily (nodes to ::1)•  /remote/<master-name> namespace for non-local nodes: –  Nodes on different master can have the same name –  Less collisions –  Namespace of the node contains its approximate location20.09.2012 Luis Roalter 7
  8. 8. Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz Technische Universität MünchenProxy Master Concept•  Replace a full ROS master•  Looks for another master and redirects all traffic to it•  Very small memory footprint as no internal state has to be kept –  Interesting for embedded devices20.09.2012 Luis Roalter 8
  9. 9. Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz Technische Universität MünchenNaming in ROS: Metadata for Nodes•  Achieve a common and collision free namespace•  No reconfiguration of any node for a specific network layout•  Central set of rules controls the whole namespace•  Nodes can look for services of local nodes or search the whole namespace20.09.2012 Luis Roalter 9
  10. 10. Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz Technische Universität MünchenRouting of Traffic Between Different Networks•  Routes access to topics –  Reduce network load for nodes –  Interesting for low bandwidth and low power nodes (wsn)•  No benefit when calling services•  Usage of a VPN tunnel between two machines can be used to bridge two networks –  If a tunnel fails, the two networks continue to operate autonomously20.09.2012 Luis Roalter 10
  11. 11. Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz Technische Universität MünchenSecurity Risks•  Problems may occur due to problems in the HTTP-calls –  DoS (Denial of Service) –  Man-in-the-Middle Attack•  The attacker may fakes information that leads the robot trough the wall –  Integrity of data –  Certificates for connections –  Encrypting of data transferred20.09.2012 Luis Roalter 11
  12. 12. Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz Technische Universität MünchenAdapting ros_comm  ros_comm6•  Full IPv6 support for the master, client and libraries•  ROS extensively uses names to address other nodes•  Names can be provided by: –  /etc/hosts and regular stateless address auto configuration –  By DHCPv6 –  DHCPv6 allows to specify how the IP address is generated•  IPv6 is disabled by default and controlled with the environment variable $ROS_IPV6 –  Has been tested with the PR2 simulation, virtual machines and on network running on a set of Beagle Boards –  Implemented for C++ and Python; Java and Lisp still missing20.09.2012 Luis Roalter 12
  13. 13. Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz Technische Universität MünchenStability Enhancements•  Better handling of temporary errors due to name resolving: –  Nodes can loose connections over a longer period of time and get found again –  IP can change as long as the name stays the same –  There is no timeout for local nodes if they loose the connection. This could be a problem as the master does not check for alive nodes20.09.2012 Luis Roalter 13
  14. 14. Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz Technische Universität MünchenPlanned implementation•  Local sync node registers with remote master•  The remote master send updates of its status to the sync node•  The local sync node updates the local master with new information•  The local master informs local nodes about new remote nodes•  All remote nodes are put into the /remote/-namespace –  Prevents cycles: The sync node only cares about changes of nodes which are not in the /remote/-Namespace20.09.2012 Luis Roalter 14
  15. 15. Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz Technische Universität MünchenThe “Multimaster”•  Fully mashed network between sync nodes and the masters –  Other sync nodes are discovered using multicast –  High network load for masters with frequent changes –  High failure tolerance if a master is not reachable anymore •  Nodes of an unreachable master are still available •  All the network is still connected on loss of a master20.09.2012 Luis Roalter 15
  16. 16. Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz Technische Universität MünchenMetadata for Nodes•  Generate system wide and unique topic and service names•  They may contain: –  Name, location, function, owner and group of a node –  Name, location, function and group for each topic and service  20.09.2012 Luis Roalter 16
  17. 17. Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz Technische Universität MünchenTransformation service•  Metadata is loaded as XML by roslaunch as a parameter –  Can also be YAML•  System node provides a transformation service –  No change to the client libraries needed –  Transformation is encapsulated, implementation resides in a single place –  Returns the namespace of specific topic/service –  Remap commands in launch-files will still work for incoming topics•  Use XSLT processor to apply an XSLT style sheet –  XSLT gets loaded at the node start-up –  XSLT must be the same for the whole system•  ROS-wide naming service, also usable for additional features for ROS20.09.2012 Luis Roalter 17
  18. 18. Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz Technische Universität MünchenRouting between sync nodes•  Replaces the fully meshed network with a routed network –  Total bandwidth usage gets reduced –  Makes the system more brittle•  Building routes between different networks: –  Discovery of other sync nodes might fail in routed networks –  Master and Sync-Node need to communicate to connect two networks –  No more problems to reach each other20.09.2012 Luis Roalter 18
  19. 19. Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz Technische Universität MünchenRouting for topics and services•  Local sync nodes registers itself with the local master•  Local nodes contact their sync node, which forwards the request through the routed network to remote sync nodes•  Remote sync node subscribes to the topic/calls the service20.09.2012 Luis Roalter 19
  20. 20. Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz Technische Universität MünchenSecurity Implementation•  Provide data integrity trough checksums and pre-shared secrets (e.g. per node or service)•  Encrypt connections by certificates•  Missing failure tests for the ROS communication stack: –  DoS Attacks –  Code injections –  Manipulation of connections (overriding parameters)•  Security concept for ROS20.09.2012 Luis Roalter 20
  21. 21. Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz Technische Universität München Thank you for your attention! Questions? ? ? roalter@tum.de www.vmi.ei.tum.de/team/luis-roalter.html20.09.2012 Luis Roalter 21
  22. 22. Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz Technische Universität MünchenPaper Reference•  Please find the associated paper at: https://vmi.lmt.ei.tum.de/publications/2011/IE11_preprint.pdf•  Please cite this work as follows:•  Luis Roalter, Andreas Möller, Stefan Diewald, Matthias Kranz. 2012. Developing Intelligent Environments: A Development Tool Chain for Creation, Testing and Simulation of Smart and Intelligent Environments In: Proceedings of the 7th International Conference on Intelligent Environments (IE2011), pp. 214-221, Nottingham, UK, July 201120.09.2012 Luis Roalter 22
  23. 23. Distributed Multimodal Information Processing GroupProf. Dr. Matthias Kranz Technische Universität MünchenIf you use BibTex, please use the following entryto cite this work: @INPROCEEDINGS{ie2011, author = {Roalter, Luis and M{"o}ller, Andreas and Diewald, Stefan and Kranz, Matthias}, title = {{Developing Intelligent Environments: A Development Tool Chain for Creation, Testing and Simulation of Smart and Intelligent Environments}}, booktitle = {Proceedings of the 7th International Conference on Intelligent Environments (IE)}, year = {2011}, pages = {214--221}, month = {july}, doi = {10.1109/IE.2011.43}, isbn = {978-0-7695-4452-6}, keywords = {Android, Development, Development Process, Intelligent Environments, Middleware, Mobile Devices, ROS, Smart Spaces}, numpages = {8} }20.09.2012 Luis Roalter 23

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