The Underwater Systems Program at the Porto University

1. The Underwater Systems Program at the Porto University Nuno Alexandre Cruz FEUP-DEEC Rua Dr. Roberto Frias 4200-465 Porto, Portugal http://www.fe.up.pt/~nacruz Laboratório de Sistemas e Tecnologia Subaquática Faculdade de Engenharia da Universidade do Porto http://www.fe.up.pt/~lsts

2. Outline • The Underwater Systems and Technology Laboratory • Vehicles • Autonomous underwater vehicles • Remotely operated vehicle • Systems and technology • Embedded computer systems • Navigation systems • Advanced mission concepts • Conclusion

3. The Underwater Systems and Technology Laboratory • Mission Design innovative solutions for oceanographic and environmental applications • People 4 Faculty staff 10 researchers • Vehicles Autonomous submarines Remotely operated submarine • Technologies Navigation and control Acoustic networks Networked control systems Power/computer systems • Applications Monitoring sea outfalls Coastal oceanography Underwater archaeology Inspection and intervention SUMARE Workshop, Villefranche-sur-Mer, 15-16 October 2003 Artwork Courtesy of Michael Incze, NUWC

4. National Administração dos Portos do Douro e Leixões Centro de Investigação Marinha e Ambiental Instituto Superior de Engenharia do Porto Instituto Hidrográfico International University of California at Berkeley, CA, USA Woods Hole Oceanographic Institution, MA, USA Naval Postgraduate School, CA, USA Cooperation

5. Vehicles Autonomous Underwater Vehicles

6. REMUS class AUV (WHOI) Length: 1.8m Diameter: 20 cm Weight in air: 35 kg Max speed: 2 m/s Max range: 100 km Payload sensors Sidescan Sonar CTD Echo sounder Optical backscatter (Video camera) … Isurus AUV (1997)

7. Customization at LSTS • Computational system • On-board software • Mission programming • Integrated navigation system • Power supply and power management • Actuation system

8. Operating the Isurus AUV Mission Support System Small boat Laptop Acoustic navigation network Operational Procedures • Acoustic network setup • Mission programming • Vehicle launching • ... • Vehicle recovery • Data download and processing

9. New Generation AUV (2003) Main features Low cost Carbon fiber hull Modular sensor adapters Payload: 8 kg Depth rating: 150 m Autonomy: 20 hours + 2 vert. & 2 horiz. fins 1 propeller

10. Isurus Missions Bathymetry Oceanographic data collection Environmental monitoring

11. Estuary of Minho River (1998+) • Width: 1-2 km • Depth: 2-5 m • Currents: over 1m/s • Mission Profile • NW-SE cross sections, 50 m apart • Section length: 700-1200 m • Tracks repeated for various depths • Data collected: • Temperature and Salinity (CTD) • Bathymetry (CTD & Echosounder)

12. Bathymetry Depth (m) North (m) East (m) Estuary of Minho River – Results

13. Temperature and Salinity (@1m depth) North (m) North (m) East (m) East (m) Estuary of Minho River – Results

14. Tapada Do Outeiro (2000+) Mission Objectives • Study the impact of discharges from thermoelectric power plant • Assess the erosion of the river bed Mission Data • Temperature • Bathymetry profiles

15. Aveiro Sea Outfall (2002+) Mission Objectives • Evaluation of environmental impact of sewage outfall • Find and map the plume Mission Scenario • Open sea • 2 km off the coast of Aveiro • 20 m of depth

16. Aveiro Sea Outfall – Planning Mission Planning • Reference data collection • Simulation of plume behavior • Delimitation of mission area • Mission programming Mission Data • Temperature • Salinity • Optical Backscatter

17. Aveiro Sea Outfall - Operations

18. 2 4 10 Aveiro Sea Outfall - Results Temperature and Salinity 4 2 10

19. Aveiro Sea Outfall – Lessons • Launching an AUV at open sea is hard • Recovering an AUV from open sea is VERY hard • Murphy is ALWAYS watching • Safety measures are never too many Wave Height at Leixões 2002-07-26 to 2002-08-02 Mission Duration

20. Vehicles Remotely Operated Vehicle

21. The IES Project (1999-2002) • Objectives • Develop an automated system for the inspection of underwater structures • Provide non-trained operators with autonomous and semi-autonomous operation modes • Strategy • Acquire a customized version of a commercial ROV • Integrate on-board computational system • Install navigation and inspection sensors • Implement a set of automated maneuvers

22. Original ROV (2000) Customized Vehicle • Phantom 500 S (Deep Ocean Engineering) • Electronics compartment • Enlarged frame • Increased flotation • Extra motor power(4 * 1/8 hp)

23. ROV Hardware Project Console Umbilical ROV ComputationalSystem InterfaceDevices PowerManagement NavigationSensors InspectionSensors Actuators Compass Inclination Depth Video Sonar Picture Thrusters Lights Pan & Tilt Doppler IMU Acoustics

24. ROV Hardware Development Main container • Computational system • Navigation system • Interface devices • Power distribution Small containers • Power distribution • Power management • Motor control • Interface devices

25. Current ROV Configuration • Inspection system • Camera: Inspector (ROS) • Pan and Tilt unit (Imenco) • Lights: up to 600W (DSP&L) • Forward looking sonar (Imagenex) • Navigation • DVL: Argonaut (Sontek) • IMU: HG1700 (Honeywell) • Digital Compass: TCM2 (PNI) • Depth sensor, 730+ (PSI) • Acoustic Tx/Rx: 20-30 KHz • Computational system • PC/104 stack, Pentium PC • QNX RTOS • Ethernet Power supply Junction box Umbilical Winch Spare kit

26. ROV Modes of Operation Modes of operation 2.Teleprogramming:Pre-programmed maneuvers 1.Teleoperation:Direct commands using a joystick Maneuver Parameters Controls Real-time video Motion Plan Sonar Data Environment Map Internal State

27. ROV Operations at APDL • Objectives • Detect corrosion in steel plates protecting walls • Register video footage with localization data • Tag features for diver intervention or latter reinspection Inspected Structures

28. ROV Operations at APDL • Main Difficulties • Reduced visibility (<0.5m) • Boundary perturbations • Cable dynamics • Solutions • High sensitivity camera • Variable illumination • Multiple sensor fusion for navigation and control • Navigation info at the console

29. Systems and Technologies

30. Based on PC/104 technology Small form-factor Plenty of COTS vendors and solutions Low-cost boards Software applications and drivers developed for RTOS Several systems in operation Underwater vehicles (AUV/ROV) Automated trucks and busses Embedded Computational Systems

31. Navigation Systems • Internal devices • Digital compasses • Doppler velocimeters • Inertial systems • Pressure sensors (depth) • Acoustic Tx/Rx boards • Algorithms • LBL navigation • Sensor fusion (Kalman filter) • Post-mission trajectory smoothing • External tracking • Navigation networks • Acoustic beacons • Surface buoys d1 d2 baseline (not to scale)

32. Vehicle Navigation • Kalman filter based algorithm • Filter state: horizontal position and water current • High rate dead-reckoning data • Low rate range measurements • Real-time transponder selection • Covariance matrix updated in real time • Interrogation sequence driven by innovation potential

33. Post Mission Trajectory Smoothing Trajectory detail real-time • Algorithm based on the Rauch-Tung-Striebel nonlinear smoother • State similar to the online filter • Estimates depend on past and “future” data • Uses data recorded on the on-board computer smoothed Uncertainty real-time smoothed

34. txponder detects & replies vehicle detects & pings txponder #2 txponder detects & replies vehicle detects & pings txponder #1 txponder detects & replies vehicle pings txponder #1  t1  t1  t4  t4  t1  t2  t3  t2  t3  t2 time ping #1 detected ping #2 detected ping #1 detected 2*  t1 +  t2 +  t3 2*  t4 +  t2 +  t3 time Passive Tracking Algorithm

35. External Tracking Mechanism • Normal operation • Listenning device just detects pings sent by the vehicles • After two interrogations, a range is computed • Listenning device can be located anywhere within acoustic range (including other AUVs!) • Vehicles keep navigating at the end of mission • Emergency operation • Simple commands can be sent to the vehicles • Vehicles carry an automatic responder • Ranges can be estimated even with computer system shut down

36. Mission Tracking Software • Interface to the navigation beacons • display of acoustic signals being transmitted and received • map the position of the surface buoys (GPS) • map the position of the vehicles • reconfiguration of the frequency pairs • transmission of “special” commands • Flexible operation • runs on any laptop connected to a radio modem • may run on several locationssimultaneously

37. Acoustic Navigation Network Multifrequency acoustic beacon • Multi-channel transmitter and receiver • Programmable frequency pairs • Simultaneous navigation of multiple vehicles • Medium frequency signals (20-30khz), over 2km range Surface Buoys • Stainless steel structure • Polyurethane flotation disc • GPS receiver • Radio modem

38. Multipurpose Surface Buoy • Acoustic navigation • Moored sensors • Communication relay Radio antenna Waterproofcontainer Fiberglass coated Polyurethane foam Underwater cablesand connectors Multifrequency Transponder Nylon/PVCcylinder Acoustic transducer To anchor

39. Advanced Mission Concepts

40. Objectives Development of a new generation AUV Simultaneous navigation of multiple AUVs Coordinated operation of AUVs Specification and control of sensor driven missions The PISCIS Project (2002-2005) • LSTS Approach • Improvement in mechanical design • Development of acoustic navigation systems • Synthesis of controllers for networked vehicles • Consortium • FEUP, CIMAR, APDL, ISEP

41. Advanced Mission Concepts • Real-time adaptive sampling • Model of oceanographic processes • Coarse survey to localize features • Track features and identify model parameters • Cooperative missions • Each vehicle makes a local measurement • Vehicles share a minimum of data • Gradient following • Detect and follow a given gradient • Possibilities for single and multiple vehicles

42. Conclusions and Future Work • Conclusions • The LSTS team has accumulated valuable expertise in development and integration of underwater systems and technologies • Low operational costs allowed for development validation by intensive field operations • Research has been driven by end-user requirements and strongly influenced by mission results • What’s ahead? • New AUV expected to be tested during 2003 • New AUV fully operational in 2004 • Navigation of multiple AUVs expected during 2004 • Coordinated operation of AUVs expected during 2004 • Communication between AUVs, buoys and shore during 2004 • New sensors for ROV during 2004 • Intervention capabilities for ROV during 2004 SUMARE Workshop, Villefranche-sur-Mer, 15-16 October 2003 Artwork Courtesy of Michael Incze, NUWC

43. Thank You. Questions?