| 摘要 |
An anchorless boat positioning system for establishing and maintaining a boat at a selected geographic location without the use of a conventional anchor. In one embodiment, a steerable thruster is used whose thrust and steering direction are determined and controlled on the basis of position information signals received from global positioning system (GPS) satellites, relative steering angle between the boat and the thruster and boat heading indication signals from a magnetic compass. The system continuously monitors the position and heading of the boat and compares it with the stored coordinates of the selected anchoring location(s) to generate control signals for the steerable motor. Several modes of operation are disclosed and Euler transformations for offset antenna placement for error reduction are taught. Proportional, integral, and derivative control (PID) of four constants of vessel control is also provided. Multiple thrusters in various arrangements are also provided to control either the orientation of the boat or a second point of interest on the boat at a second geographic location.
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