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Artificial intelligence-assisted station keeping for improved drillship operations
Table 3. Hydrostatic properties

Parameter Symbol Magnitude Units
Longitudinal CoG LCG 105 m
Transverse CoG TCG 0 m
Vertical CoG VCG 3.63 m
Volume displacement ∇ 47037.348 m 3
Longitudinal CoB LCB 105.81 m
Transverse CoB TCB 0 m
Vertical CoB VCB −4.55 m
Distance between B and G BG 8.182 m
Transverse metacentric height GM T 2.07 m
Longitudinal metacentric height GM L 447.178 m
Transverse metacentric radius BM T 10.253 m
Longitudinal metacentric radius BM L 447.17 m
Abbreviations: CoB: Center of buoyancy; CoG: Center of gravity.

4.3. Response amplitude operators ensuring effective station-keeping and optimizing
operational efficiency of the drillship.
As previously outlined, the dynamic response of
the drillship was evaluated under varying wave di-
rections to gain a comprehensive understanding of
its behavior. This results section begins by con-
centrating on the surge in the degree of freedom.
The surge’s response amplitude operator (RAO)
was computed for waves approaching the vessel
from different angles. This computation provides
crucial insights into the vessel’s longitudinal mo-
tion (surge), offering a clear picture of its behavior
in response to diverse sea conditions. The plot- Figure 10. Surge for 0 ◦
ted surge RAO, representing multiple wave direc- Abbreviation: RAO: Response amplitude operator
tions, highlights significant response patterns and
trends. These results form the basis for a more
detailed examination and validation of the AI-
driven control system, ensuring its effectiveness
in maintaining the vessel’s station-keeping under
dynamic conditions. Figures 10–15 show RAO
◦
◦
plots for 0 and 90 wave heading in surge, sway,
and yaw motion, respectively.
4.3.1. Response amplitude operator for wave
heading of 0 ◦ Figure 11. Sway for 0 ◦
Abbreviation: RAO: Response amplitude operator
Surge is dominant at low frequencies, while sway
4.3.2. Response amplitude operator for wave
demonstrates complex dynamics with multiple heading of 90°
resonances. Yaw motion shows a moderate influ-
ence, with a wave frequency-dependent behavior The surge and sway RAO plots confirm a few in-
distinct from that of sway and surge. Each de- sights about the vessel’s dynamic behavior, which
gree of freedom exhibits unique resonance char- are necessary to activate an AI-driven controller.
acteristics based on wave frequency, emphasizing The sway and surge responses decrease with the
the need for adaptive control to counteract dy- increase in wave frequency, with higher magnitude
namic forces in varying sea conditions. This dy- at low wave frequencies. This is important for the
namic behavior underscores the importance the controller to initiate a higher thrust at lower wave
importance of incorporating surge, sway, and yaw frequencies. In contrast, the yaw RAO plots show
dynamics into an AI-based station-keeping algo- the influence under a large wave frequency band
rithm. The plots further emphasize that address- (Figures 12, 15, and 18), highlighting its sensitiv-
ing all three degrees of freedom is crucial for ity to wave frequencies.
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