Chapter 3 - Dynamics of Marine Vessels
Chapter 3 - Dynamics of Marine Vessels Chapter 3 - Dynamics of Marine Vessels
8 3.2.4 Ballast Systems SeaLaunch: An example of a highly sophisticated pretrimming system is the SeaLaunch trim and heel correction system (THCS): This system is designed such that the platform maintains constant roll and pitch angles during changes in weight. The most critical operation is when the rocket is transported from the garage on one side of the platform to the launch pad. During this operation the water pumps operate at their maximum capacity to counteract the shift in weight. A feedback system controls the pumps to maintain the correct water level in each of the legs during transportation of the rocket Ivar Ihle – TTK4190 Spring 2006
9 3.2.4 Ballast Systems Automatic Pretrimming using Feedback from In the manual pretrimming case it was assumed that wr zd, d, d =0. This assumption can be removed by using feedback. The closed-loop dynamics of a PID-controlled water pump can be described by a 1st-order model with amplitude saturation: Tjṗ j pj satpdj T j (s) is a positive time constant p j (m³/s) is the volumetric flow rate pump j p d j is the pump set-point. The water pump capacity is different for positive and negative flow directions: satpdj p j,max pj p j,max pdj − pj,max ≤ pdj ≤ pj,max − − pj,max pdj pj,max pjmax , 0.63 pjmax , p j T j Ivar Ihle – TTK4190 Spring 2006 t
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8<br />
3.2.4 Ballast Systems<br />
SeaLaunch:<br />
An example <strong>of</strong> a highly sophisticated pretrimming system is the<br />
SeaLaunch trim and heel correction system (THCS):<br />
This system is designed such<br />
that the platform maintains<br />
constant roll and pitch angles<br />
during changes in weight. The<br />
most critical operation is when<br />
the rocket is transported from<br />
the garage on one side <strong>of</strong> the<br />
platform to the launch pad.<br />
During this operation the<br />
water pumps operate at their<br />
maximum capacity to<br />
counteract the shift in weight.<br />
A feedback system controls the pumps to maintain the<br />
correct water level in each <strong>of</strong> the legs during<br />
transportation <strong>of</strong> the rocket<br />
Ivar Ihle – TTK4190 Spring 2006
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