1. TMR4225 Marine Operations, 2004.02.12 - ROV intro AUV Types
HUGIN development
Motion equations
Force and moment estimation
Exercise

2. AUV – UUV definitions AUV UUV
An Autonomous Underwater Vehicle which carries its own power and does not receive control signals from an operator during a mission
UUV
An Untethered Underwater Vehicle carrying its own power and receiving control signals from an operator (hydroacoustic or fibre optic cable)

3. Two characteristic shapes
Torpedo shape
Originally military application, also used for scientific vehicles
Tactical Acoustic System
Mine Search System
Remote Surveillance System
Low drag shape
Pearson form
Basic shape used for initial development studies of HUGIN

4. Torpedo shape - Autosub

5. Low drag shape – HUGIN 3000

6. AUV examples

7. Important AUV web sites

8. AUV design challenges Suspension in air
Centre of gravity
Lifting arrangements
Penetration of sea surface
Resistance – propulsion – energy capacity
Steering and manoeuvring
Dynamic stability
Control units (thrusters, rudders)
Control system design

9. Mathematical model SNAME axis system Nielsen (chapter 4)
+ X forwards
+ Z downwards
Nielsen (chapter 4)
+ X aftwards
+ Z upwards
Refnes (chapter 2)

10. 6 Degree of freedom motion equations
Nielsen
Second order partial differensial equations with constant coefficient
Frequency dependent hydrodynamic coefficients
Matrix form
Refnes
First order nonlinear partial differential equations with constant coefficients (state space formulation)

11. 6 Degree of freedom motion equations
Gertler and Hagen – Submarine equations
Second order, nonlinear partial differensial equation
Constant coefficients (some may be speed dependent)
Component form
Simplified models
Decoupled equations for motions in vertical and horizontal plane
Linear equations for study of dynamic stability and small perturbations around a steady state condition

12. Group work
A: Discuss the statements on forces/moments on pages 5 – 8 in Refnes, Chapter 2
B: Discuss methods to estimate forces/moments
C: Present the results for the other groups
Group 1: Inertial forces
Group 2: Coriolis and centripetal forces
Group 3: Hydrodynamic damping and lift forces
Group 4: Restoring forces and moments due to gravity/buoyancy
Group 5: Control forces
Group 6: Environmental forces (waves and currents)
Group 7: Interaction forces

13. Methods for estimating forces/moments
Theoretical models
Potential flow, 2D/3D models
Lifting line/lifting surface
Viscous flow, Navier-Stokes equations
Experiments
Towing tests (resistance, control forces, propulsion)
Oblique towing (lift of body alone, body and rudders)
Submerged Planar Motion Mechanism
Cavitation tunnel tests (resistance, propulsion, lift)
Free swimming

14. Methods for estimating forces/moments
Empirical models
Regression analysis based on previous experimental results using AUV geometry as variables

15. AUV – Theoretical models
Potential theory
Deeply submerged, strip theory
VERES can be used to calculate
Heave and sway added mass
Pitch and yaw added moment of inertia
VERES can not be used to calculate
Surge added mass
Roll added moment of inertia

16. AUV – Theoretical models
3D potential theory for zero speed - WAMIT
All added mass coefficients
All added moment of inertia coefficients
Linear damping coefficient due to wave generation
Important for motion close to the free surface
More WAMIT information

17. AUV- Theoretical models
Viscous models
Solving the Navier Stokes equations
Small Reynolds numbers (< 1000) : DNS
Medium Reynolds numbers (< 10**5) : LES – Large Eddy Simulation
High Reynolds numbers (> 10**5) : RANS – Reynolds Average
Navier Stokes

18. NTNU/Marine Technology available tools:
2 commercial codes
Fluent
CFX
In-house research tools of LES and RANS type
More info: Contact Prof. Bjørnar Pettersen

19. AUV – Experimental techniques
Submerged resistance and propulsion tests
Towing tank
Cavitation tunnel
Submerged Planar Motion Mechanism tests
Oblique towing test
Lift and drag test, body and control planes

20. AUV – Experimental techniques
Free sailing tests
Towing tank
Ocean basin
Lakes
Coastal waters
Free oscillation tests/ascending test
Water pool/ Diver training pool

21. HUGIN history AUV demo (1992-3) HUGIN I & II (1995-6)
Diameter: m Length: 3.62/4.29 m
Displacement: m**3
HUGIN I & II (1995-6)
Diameter: m Length: 4.8 m
Displacement: m**3
HUGIN 3000C&C and 3000CG ( )
Diameter: m Length: 5.3 m
Displacement: m**3

22. HUGIN 3000 Characteristics
Operational depth: m
Mission lenght: hours
Nominal speed: knots
Position accuracy: m for water depths > 2000 m
Costs: – 45 mill NOK (2002)
Number produced (2002)

23. NTNU/MARINTEK HUGIN involvement
AUV demo (1992-3)
Model test in cavitation tunnel, open and closed model, 2 tail sections (w/wo control planes)
Resistance, U = {3,10} m/s
Linear damping coefficients for sway, yaw, heave and pitch, yaw/trim angles {-10, 10} degrees
3D potential flow calculation
Added mass added moment of intertia
Changes in damping and control forces due to modification of rudders
Student project thesis

24. NTNU/MARINTEK HUGIN involvement
Resistance tests, w/wo sensors
Model scale 1:4
Max model speed 11.5 m/s
Equivalent full scale speed?
Findings
Smooth model had a slightly reduced drag coefficient for increasing Reynolds number
Model with sensors had a slightly increased drag coefficient for increasing Reynolds numbers
Sensor model had some 30% increased resistance

25. HUGIN field experience
Offshore qualification seatrials (1997)
Åsgard Gas Transport Pipeline route survey (1997)
Pipeline pre-engineering survey (subsea condensate pipeline between shorebased process plants at Sture and Mongstad) (1998)
Environmental monitoring – coral reef survey (1998)
Fishery research – reducing noise level from survey tools (1999)

26. HUGIN field experience
Mine countermeasures research (1998-9)
Ormen Lange pipeline route survey (2000)
Gulf of Mexico, deepwater pipeline route survey (2001 ->)

27. Actual HUGIN problems Inspection and intervention tasks
Adding thrusters to increase low speed manoeuvrability for sinspection and intervention tasks
Types, positions, control algorithms
Stabilizing the vehicle orientation by use of spinning wheels (gyros)
Reduce the need for thrusters and power consumption for these types of tasks
Docking on a subsea installation
Guideposts
Active docking devices on subsea structure (robotic arm as on space shuttle for capture of satelittes)

28. Actual HUGIN problems Roll stabilization of HUGIN 1000
Low metacentric height
4 independent rudders
PI type regulator with low gain, decoupled from other regulators (heave – pitch – depth, sway – yaw, surge)
Task: Keep roll angle small ( -> 0) by active control of the four independent rudders

29. Actual HUGIN problems
Norwegian Defence Research Institute (FFI) and Kongsberg Simrad are looking for talented students that would like to work on problems related to design, control and operational performance of AUVs/UUVs

30. Future system design requirements
Launching/ pick-up operations up to Hs = 5 m when ship is advancing at 3-4 knots in head seas
Increasing water depth capability
Increased power capability
Operational speed knots
Mission length 3- 4 days

31. Exercise no. 4 Linear equations for horizontal plane motion of an AUV
Dynamic stability check
Calculation of yaw response using zigzag tests

32. Additional reading B. Jalving, K. Vestgård and N. Størkersen:
- Detailed seabed surveys with AUVs (27 pages)
M. Mandt, K. Gade and B. Jalving:
- Integrating DGPS-USBL position measurements with inertial navigation in the HUGIN 3000 AUV (9 pages)

33. TMR4225 Marine operations,
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