In this graduation thesis the feasibility of a camera as sensor for nautical operations is investigated. In
aerospace and automotive industries autonomous vehicles are already widely tested and used. However
the marine industry has fallen behind in this development. Therefore this research is focussing on
automation in the maritime sector. First a system was developed which measures distance and heading
from a video feed. Thereafter simulink models were made to develop a system that autonomously can
perform nautical operations. For this research multiple operations have been modeled. First of all
the platform approach and the replenishment approach. In these operations the system should be able
to approach a stationary or moving target. Also station keeping after the approach is required. The
complexity of the operations was increased with the choice for follow the leader from the maneuvering
operations. Finally the avoidance of upcoming collisions was modeled. The models for all of these
operations were rst developed and tested with an oine model. This enabled a quick and accurate
controller tuning. The rst real test for these models was done in a ship handling simulator. Here the
models were tested and the in
uence of environmental conditions was measured. In the simulator all
models performed quite well. However the performance is largely limited by the choice for the camera
and environmental conditions. The most interfering conditions are lateral incoming waves, fog and light.
Models for small scale testing were developed, but the communication between dierent components and
the control system proved to be a large issue. Therefore these models could not be tested. All in all
this research shows that after improving system component, a camera system can very well be used as a
sensor for autonomous operations at sea.

This paper treats the numerical modelling of the behaviour of a sand core covered by rocks and exposed to waves. The associated displacement of the rock is also studied. A design that allows for erosion and deposition of the sand core beneath a rock layer in a coastal structure requires an accurate prediction method to assure that the amount of erosion remains within acceptable limits. This work presents a numerical model that is capable of describing the erosion and deposition patterns inside of an open filter of rock on top of sand. The hydraulic loading is that of incident irregular waves and the open filters are surface piercing. Due to the few experimental data sets on sediment transport inside of rock layers, a sediment transport formulation has been proposed based on a matching between the numerical model and experimental data on the profile deformation inside an open filter. The rock layer on top of a sand core introduces a correction term in the Exner equation (the continuity equation for sediment and change in bed level). The correction term originates from the fact that the sand can only be deposited in the pores of the filter material. The numerical model is validated against additional data sets on the erosion and deposition patterns inside of an open filter. A few cases are defined to study the effect of the sinking of the filter into the erosion hole. The numerical model is also applied to several application cases. The response of the core material (sand) to changes in the wave period and wave height is considered. The effect of different layouts of the filter is studied in order to investigate the effect of different filter profiles on the resulting erosion. Finally, it is studied how much the design of a hydraulically closed filter can be relaxed to obtain a reduction in the design requirements of the filter thickness, while the deformation to the sand core remains acceptably small.

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Permeable coastal structures typically contain granular filters in one or more layers. These filters are normally geometrically tight to prevent material washout. A cheaper alternative is a geometrically open filter where only minimal base material loss or settlement occurs. In Van Gent and Wolters (2015) physical model tests were performed to estimate the amount of erosion and accretion of sand underneath one or two layers of rock. Here, a numerical model has been applied to compute hydraulic gradients at the internal sand-rock interface for conditions in which the structure is exposed to wave action. The results show that the model can accurately compute hydraulic gradients at the internal rock-sand interface and that the position of erosion and accretion of sand can be predicted. The performed parameter analysis shows which parameters affect the hydraulic gradients and which parameters do not. Moreover, processes that contribute to erosion and accretion have been analysed.

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