A Bottom-Following Preview Controller for Autonomous Underwater Vehicle

1. A Bottom-Following Preview Controller for
Autonomous Underwater Vehicles
Carlos Silvestre, Rita Cunha, Nuno Paulino, and António Pascoal
By:
Ahmed El Sheikh
MSc Student, Mechatronics and Robotics, Sghool of Innovative Design, E-JUST
ahmad.elsheikh@hotmail.com

2. Carlos Silvestre: PhD, (IST), Lisbon,
Portugal.
Rita Cunha: PhD, (IST), Lisbon,
Portugal.
Nuno Paulino: M.Sc, (IST),
Lisbon, Portugal.
António M. Pascoal, PhD,
(IST), Lisbon, Portugal

3. Overview
• State of The Art
• Vehicle Dynamics
• Error Space
• Preview Problem Formulation
• Discrete Time Controller Design
• Reference Path
• Implementation
• Simulation Results

4. State of The Art
• Solving the problem of bottom –following for AUV
• Using the echo sounders to evaluate the terrain
characteristics
• AUV linearized error dynamics for a pre-de ned set of
operating regions
• Using the LMIs to solve the H2 state feedback control
problem
• Using the D-Methodology to implement non-linear
controller.

5. Vehicle Dynamics
INFANTE vehicle
Vehicle Characteristics
Length(m) 4.5
Width(m) 1.1
Height(m) 0.6
Thrusters 2 (Propellers & Nozzles)

6. Vehicle Dynamics(cont’)
Coordinate frames: inertial {I}, Body {B}
Serret {T}, Desired Body {C}

7. Error Space
The vector of control inputs is:
And the output vector is:
Assume straight line, Vr=qc=0,

8. Error Space(cont’)
Error linearization
Discretization

9. Preview Problem Formulation
Two echo sounders are used to Reference path—slope discontinuity
measure the characteristics of the
seabed ahead of the AUV.
The seabed signal
The linear error dynamics

10. Preview Problem Formulation(cont’)

11. Discrete Time Controller Design
The Linear Matrix Inequalities Theoretical Background
(LMIs)approach is used to
design the discrete time H2
Feedback interconnection
state feedback controller

12. Discrete Time Controller Design(cont’)
Preview Controller Synthesis Technique

13. Reference Path
Sensor readings &offset to obtain the data points
•Adding the elevation offset
•Output inertial frame {I} - x coordinate
•Points- straight lines
Final computed path (segments of straight lines)

14. Implementation
Affine Parameter-Dependent Description of Operating regions parameterized by
The plant

15. Implementation (cont’)
Implementation setup using gain scheduling and the D-methodology
D- Methodology
•Integrators (input)
•Differentiator (needed
•Stability Characteristics
•Linearization
•Auto trimming Property

16. Implementation (cont’)
Evolution of the preview gains f(t)
Closed-loop system’s H2 norm
Trajectories described by the vehicle

17. Simulation Results
The control objective is to achieve a constant 15-mbottom elevation offset.
Descending phase Climbing phase.
Error vector Xe (t)

18. The Papers I’ve presented
The Papers
Paper 1 A SURVEY OF UNDERWATER VEHICLE
NAVIGATION: RECENT ADVANCES AND
NEW CHALLENGES
Published
Paper 2 An Adaptive Controller for Underwater Vehicle-Manipulator Systems Including
Thruster Dynamics
Published Proceedings of the 2010 International Conference on
Modeling, Identification and Control, Okayama, Japan, July 17-19,2010
Paper 3 A Bottom-Following Preview Controller for
Autonomous Underwater Vehicles
Published IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY, VOL. 17, NO. 2,
MARCH 2009

19. Any Questions