1. TMR4225 Marine Operations,
Dynamic stability of underwater vehicles
Hugin status
Russian proposal for oil and gas production in Arctic
Odyssey IV

2. Dynamic stability Linear equations can only be used when
The vehicle is dynamically stable for motions in horisontal and vertical planes
The motion is described as small perturbations around a constant motion, either horisontally or vertically
Small deflections of control planes (rudders)

3. Dynamic stability (cont.)
For horisontal motion the equation (2.15) can be used if roll motion is neglected
The result is a set of two linear differential equations with constant coefficients
Transform these equations to a second order equation for yaw speed
Check if the roots of the characteristic equation have negative real parts
If so, the vehicle is dynamically stable for horisontal motion

4. Dynamic stability (cont.)
Characteristic equation for linear coupled heave - pitch motion:
( A*D**3 + B*D**2 + C*D + E) r’ = 0
Dynamic stability criteria is:
A > 0, B > 0 , BC – AE > 0 and E>0
Found by using Routh’s method

5. 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

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

7. 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

8. 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

9. 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

10. 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

11. 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

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

13. 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

14. 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

15. 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

16. 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)

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

18. 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)

19. 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)

20. 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

21. 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

22. HUGIN information New vessels have been ordered late 2004 and 2005
One delivery will be qualified for working to 4500 m waterdepth
New instrumentation is being developed for use as a tool for measuring biomass in the water column
Minecounter version HUGIN 1000 has been tested by Royal Norwegian Navy
More Hugin information: see Kongsberg homepage for link

23. Principal Investigator
AUV-LAB MIT
Odyssey IV
Principal Investigator
C. Chryssostomidis
F. Hover
Design Team
R. Damus
S. Desset
J. Morash
V. Polidoro

24. Russian proposal for Arctic oil and gas production
No existing infrastructure
Harsh environment (ice and low temperatures)
Using subsea vehicles for drilling and prosuction

25. Standard Field Construction Scheme

26. Underwater Drilling System
Submarine Drilling Vessel
Bottom Template

27. Consumable Replenishment System
Submarine
Support Vessel
Drilling Vessel
Transport
Container
Triton
class ROV
Transport
Container
Cargo deck

28. Mulig Stockman utbygging
SDV
TRUV
SSV
ROV BT
TLP
Container
TMS
2…3 km

29. % probability of sea ice (April) in Barents Sea (Orheim, Houston, 2005)
Shtokman

30. Example: 3 days track for iceberg (marking per 3 hours) (Orheim, Houston, March 2005)