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
Cooperation

• 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

5
Vehicles

• Autonomous Underwater Vehicles

6
Isurus AUV (1997)

• 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)

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
Estuary of Minho River Results
13
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
Aveiro Sea Outfall - Results
Temperature and Salinity
2
4
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
Thrusters
Lights
Pan Tilt
Video
Sonar
Picture
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 (DSPL)
• 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. TeleprogrammingPre-programmed maneuvers
1. TeleoperationDirect 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 (lt0.5m)
• 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
Embedded Computational Systems

• 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

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
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
Waterproof container
Fiberglass coated Polyurethane foam
Underwater cablesand connectors
Multifrequency Transponder
Nylon/PVC cylinder
Acoustic transducer
To anchor
39
Advanced Mission Concepts
40
The PISCIS Project (2002-2005)

• Objectives
• Development of a new generation AUV
• Simultaneous navigation of multiple AUVs
• Coordinated operation of AUVs
• Specification and control of sensor driven
  missions

• 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
• Whats 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?