This thesis treats the motion of a small vessel described in six degrees of freedom. There are
three are translation equations of motion and the other three are equations of angular
motion. The aim is to develop a model with a sound mathematical base and use
experimentation to find forces to aid the completion of the model, with the intention of use
in an auto pilot, by the following means:
1) By solving the equations of motion for large movements, with given sea and wind
conditions and also with given control forces and moments.
2) Deduce the forces and moments being applied from the sea etc., from the motion of
the vessel. Thus to enable the auto pilot to deduce the required additional forces and
the forces and moments applied by the water and wind and the control devices, such
as the propeller and rudder.
These two aims are achieved by analysing the transformation of axes using the standard
Euler equations. However, as Euler's angles are ordered and therefore cannot cope with
large angles which are present in the motion of a small vessel, another set of angles relating
to axes and planes have been deduced. These are then rotated and the set of three measured
angles are found in terms of the Euler angles. This is the main pan of original work in the
thesis. The rest of the thesis is then based upon these set of measured angles and a general
case mathematical model is deduced using them. This is proceeded by a functional analysis
of the vessel's motion, environment and control action's. After that the general case model is
theoretically validated by analysing the work done by ARJM Lloyd and showing how his
work is a specific case of the general case. Experimental work performed on a small vessel
is then used in the building of a mathematical model for the specific case of a small vessel,
using a set of measured angles.

Date of Award | 1997 |
---|

Original language | English |
---|

Awarding Institution | |
---|

MATHEMATICAL MODELLING OF THE DYNAMIC RESPONSE, IN SIX DEGREES OF FREEDOM, OF SMALL VESSELS IN A SEAWAY

Wallis, B. D. (Author). 1997

Student thesis: PhD