Towards Persistent Autonomy of Underwater Robotic Vehicles: Robust Control Strategies for Efficient Positioning and Interaction
Speaker: Prof. Kostas J. Kyriakopoulos
Date: 11 December 2015 Time: 12:30-14:00
Location: "Stelios Orphanoudakis" Seminar Room, FORTH, Heraklion, Crete
Host: Prof. Panos Trahanias


A common and important prerequisite for Persistent Autonomy of Unmanned Underwater Vehicles (UUVs) is advanced, platform-level, motion planning &control to efficiently handle most of the UUV platform-level motion issues in such a way as to allow motion be perceived from higher levels (Learning, Task Planning etc.) as a simple modality. At the same time the sought control scheme should handle complex task missionsand be robust enough to parameter uncertainties and disturbances due toreal sea conditions. In order to handle UUV specific needs such as limited energy and computational resources dictating low complexity motion control, model-free position and image based visual servoing schemes are presented. They do not require the vehicle parameters and guarantee prescribed, transient and steady state, performance despite external disturbances. We proceed with a Vision-based Nonlinear Model Predictive Control (NMPC) scheme where the control loop does not close periodically, but instead a self-triggering mechanism decides when to provide the next control update. This results to a significantly smaller number of measurements from vision and less frequent computations of the control law, thus reducing processing time and energy consumption. Complex real-time tasks, such as inspection and surveillance, often require high pitch angle configurations that may cause divergence of the navigation filters due to acoustic sensor limitations (DVL). Thus we propose visual servo control for UUV autonomous navigation and stabilization relative to an unknown visual target while achieving high pitch and yaw configurations. In the case ofautonomous surveillance at low visibility, multi-beam imaging sonarsreplace traditional vision and model-based sonar servo control is adopted. The proposed controller is robust to UUV external disturbances and parametric uncertainties. Inspection and surveillance can be enhanced when employing multiple cooperating UUVs. Results on energy efficient coordinated motion control of multi-agent UUVs is presented. A self triggering scheme for multi-agent systems control is developed where operational factors such as disturbances induced by sea currents as well as communication delays in underwater acoustic positioning systems (e.g. USBL) are considered. In addition to free motion (e.g. inspection/surveillance), underwater missions often require a level of interaction (e.g. valve/lever manipulation, tool grasping/carrying etc.) that can be accomplished by Underwater Vehicle Manipulation Systems (UVMS). If a certain performance criterion is adopted (e.g. optimal configuration of the end-effector according to the required task) a motion control algorithm is developed for UVMS optimal pose configuration to efficiently interact with the environment. The first part of presentation is concluded with immediate future directions towards cooperative motion and (physical) interaction control of multi-agent UVMS.

In the second part, a brief overview of our parallel research activities will be presented in areas such as:

  • Multi-agent Systems: "Distributed multi-agent provable cooperation in both continuous & discrete domains"
  • Aerial Robotics: Dynamic Flights in Dynamic Environments.
  • Neuro-Robotics: From Brain Machine Interfaces to Human Robot Interaction Applications


Prof. Kostas Kyriakopoulos (http://users.ntua.gr/kkyria) received a Diploma in Mechanical Eng. (Honors) from NTUA (1985) and the MS (1987) Ph.D (1991) in Electrical, Computer & Systems Eng. (ECSE) from Rensselaer Polytechnic Institute (RPI), Troy, NY. Between 1988-91 he did research at the NASA Center for Intelligent Robotic Systems for Space Exploration. Between 1991-93 he was an Assist. Prof. at ECSE - RPI and the New York State Center for Advanced Technology in Automation & Robotics. Since 1994 he has been with the Control Systems Laboratory (CSL) of the Mechanical Eng. Dept. at NTUA, where he served as Associate Department Head while currently serves as a Professor & Director of: (i) CSL (http://www.controlsystemslab.gr/index/), (ii) the Mechanical Design & Control Systems Division and (iii) the Departmental Computation Lab. His current interests are in the area of Embedded Control Systems applications in Sensor Based Motion Planning & Control of multi-Robot Systems (Mobile, Underwater & Aerial Vehicles / Manipulators). He has been awarded a number of fellowships including the Alexander Von Humboldt Foundation Fellowship. He has published ~280 papers to journals and fully refereed international conferences. He has contributed to 31 projects funded by the EC and Greek Sources with a total budget of ~5M€. He served and serves in the editorial committees of a number of IEEE publications and in the high-level administrative committees of a number of international conferences.

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