auto N omous, self-Learning, OPTI mal and comp L ete U nderwater S ystems NOPTILUS FP7-ICT : Information and Communication Technologies [NOPTILUS KoM WP5: Motion and Sensory Motor Control Cedris Pradalier (ETHZ) & Elias Kosmatopoulos (CERTH) May, 2011 Porto, Portugal

[Short Meeting Name], [Date], [Location]2 FP NOPTILUS Project Acronym: NOPTILUS Project Number: Project Start Date: April 2011 Duration: 4 Years Funded by: EU FP7 Program Name: Information and Communication Technologies, FP7-ICT NOPTILUS Contact Information For information regarding this Project: Check the Project Web-Site: NOPTILUS Participants 1Centre for Research and Technology (CERTH, GR) 2Faculdade de Engenharia da Universidade do Porto (FEUP, PT) 3Eidgenössische Technische Hochschule Zürich (ETH, CH) 4Delft University of Technology (TU Delft, NL) 5Telecommunication Systems Institute (TSI, GR) 6Imperial College (Imperial, UK) 7OceanScan - Marine Systems & Technology, Lda (MST, PT) 8Administração dos Portos do Douro e Leixões, SA (APDL, PT)

[Short Meeting Name], [Date], [Location]3 FP NOPTILUS Key Partners  ETHZ  CERTH  FEUP, OMST and Imperial will also contribute

[Short Meeting Name], [Date], [Location]4 FP NOPTILUS The Objective  (O8) A prerequisite for efficient and nearly- optimal AUV navigation is that each single AUV is able to accurately follow and track the assignment and navigation commands Important practical problems:  strong currents, turbulences, etc may force the AUV to significantly deviate from the assigned trajectory  in cases of poor localization the AUVs may not be able to perform state-space trajectory following.

[Short Meeting Name], [Date], [Location]5 FP NOPTILUS NOPTILUS approach to deal with these 2 problems  Combine the learning-based strategy with existing robust, nonlinear (but non-adaptive) motion control techniques.  In case of poor localization switch to sensory- motor control.  Employ a switching mechanism for appropriately activating/deactivating the motion control or the sensory-motor control module. Incorporate within the switching mechanism a collision-avoidance controller

[Short Meeting Name], [Date], [Location]6 FP NOPTILUS Motion Control  For each AUV to follow as close as possible a trajectory in 3D or 6D space  The trajectory is generated on-line by the navigation module.  «Difficult» control problem mostly due to the highly nonlinear nature of AUV dynamics and the effect of currents and turbulences

[Short Meeting Name], [Date], [Location]7 FP NOPTILUS Motion Control  Recently, many different teams have developed very efficient methods both for single- and multi-AUV motion control  Successful demonstrations in real-life  Good performance and robustness was demonstrated  Lyapunov-stability based  However, may become inefficient in cases of strong currents and turbulences  Adaptive techniques should be employed in order to enhance the efficiency of the above-mentioned methods  Existing adaptive methods «cannot do the work»: poor transients or, even, instability!

[Short Meeting Name], [Date], [Location]8 FP NOPTILUS Motion Control  A recently-developed adaptive/learning scheme overcomes the poor transient or instability shortcomings of existing adaptive methods  The key-idea of the scheme is to employ concurrent exploitation-exploration :  Calculate the «conventional» control strategy using an existing Lyapunov-stability-based scheme  Generate many perturbed versions of the «conventional» control strategy  Find – and apply – the best of the perturbed versions (using the Lyapunov function)  Concurrently estimate the effect of exogenous dynamics and other AUV systems variations

[Short Meeting Name], [Date], [Location]9 FP NOPTILUS Motion Control  The concurrent exploitation-exploration scheme converges exponentially fast to the same performance as the one that would have been achieved if the exogenous disturbance characteristics were completely known  Example (visual servo control of an aerial robot vehicle)

[Short Meeting Name], [Date], [Location]10 FP NOPTILUS Sensory-Motor Control  Why?  The solution if global positioning is not feasible  Based on vision and/or sonar readings  Idea:  Record a trajectory as a sequence of sensory-motor data: Image or/and Sonar and Control input.  Replay it by comparing observed data with the trajectory  Challenges  Initialization  Tracking  Time synchronization  Planned approach:  Vision based solutions on ground and boat robots  Adaption to sonar sensors (side scanners), possibly on Lizhbeth  Extension to the 3D/6D submarine-scenario

[Short Meeting Name], [Date], [Location]11 FP NOPTILUS State of the art Image source: Remazeilles 2004  Principle:  Visual trajectory following  Challenge:  How can this be adapted to ultrasound perception?

[Short Meeting Name], [Date], [Location]12 FP NOPTILUS Switching Mechanism  Switch based on localization accuracy  Make sure that collisions do not occur when switching (enhance the controller using a collision avoidance one especially when switch to sensory-motor control)  The Switching Mechanism should be designed in close cooperation with the Navigation Module:  Sensory-motor control is activated whenever localization is «not important» (e.g., if the goal is to come close to a target)  When the sensory-motor control is activated, the Navigation Module should take care so that localization is re-gained (by, e.g., resurfacing one of the AUVs) when localization becomes important (e.g., the AUV has come close to the target and needs to estimate its location)