Jha, Pankaj Kumar (2013) *Position and Heading Control of an Autonomous Underwater Vehicle using Model Predictive Control.* MTech thesis.

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## Abstract

Autonomous Underwater Vehicle (AUV) is currently being used for scientific research,

commercial and military underwater applications. AUV requires autonomous guidance and

control systems to perform underwater applications. This Thesis is concerned with position

and heading control of AUV using Model Predictive Control.

Position control is a typical motion control problem, which is concerned with the design of

control laws that force a vehicle to reach and maintain a fixed position. The position control

of body fixed x-axis to a fixed point using MPC toolbox of MATLAB is done here. System is

modelled Using INFANTE AUV hydrodynamic parameters. There is physical limitation on

thruster value.

Heading control is concerned with the design of control laws that force a vehicle to reach and

maintain a fixed direction. There are physical limitations on control input (Rudder deflection)

in heading control also a high yaw rate can produce sway and roll motion, which makes it

necessary to put constraint on yaw rate. The MPC have a clear advantage in case of control

and input constraints. To avoid constraint violation and feasibility issues of MPC for AUV

heading control Disturbance Compensating (DC) MPC scheme is used. The DC-MPC

scheme is used for ship motion control and gave better results so we are using the proposed

scheme to AUV heading control.

A 2 DOF AUV model is taken with yaw rate and rudder deflection constraints. Line of sight

(LOS) guidance scheme is utilised to generate the reference heading, which is to be followed.

Two types of disturbances are taken constant and sinusoidal. Then simulation has been done

for standard MPC, M-MPC and DC-MPC. A (DC) MPC algorithm is used to satisfy the state

constraints in presence of disturbance to get a better performance.

Standard MPC gives good result without disturbance. But in case of disturbance yaw

constraint is violated. At many time steps the standard MPC has no solution for given yaw

rate constraint at those time steps the constraints have been removed. The M-MPC satisfies

the constraints. The DC-MPC gives better result in comparison to standard MPC and

Modified MPC. The steady state oscillations are less in DC-MPC as compared to M-MPC for

sinusoidal disturbances.

The minimization of extra cost function in DC-MPC makes the result better than M-MPC. By

solving the extra cost function we try to make response close to that of without disturbance.

The only added complexity in DC-MPC is ni-dimensional optimization problem. Which is

very less compared to Np*ni, complexity of M-MPC. Where ni is the dimension of control

input and Np is value of prediction horizon. The feasibility of DC-MPC scheme largely

depends on the magnitude of disturbance. If disturbance is too large then this scheme is not

feasible.

Item Type: | Thesis (MTech) |
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Uncontrolled Keywords: | AUV, Position Control, Heading Control, MPC |

Subjects: | Engineering and Technology > Electrical Engineering > Power Systems |

Divisions: | Engineering and Technology > Department of Electrical Engineering |

ID Code: | 5398 |

Deposited By: | Hemanta Biswal |

Deposited On: | 19 Dec 2013 11:00 |

Last Modified: | 20 Dec 2013 11:01 |

Supervisor(s): | Subudhi , B |

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