Thrust distributing method of dynamic positioning system

Abstract

A thrust distributing method of a dynamic positioning system comprises the steps of dividing thrusters into several groups, and fixing relative angles of azimuth angles of the thrusters in each group but not fixing absolute angles; obtaining a thruster azimuth angle with slow change by a low frequency part of a control command by means of an optimization algorithm, and then thrust of the thrusters is obtained by means of the optimization algorithm, namely inputting a control command T [c , k] at the k moment into a low pass filter composed of a first-order inertial element, and then carrying out discretization to obtain the low frequency part T [k+1]; calculating the thrust fk of all the thrusters and the azimuth angles alpha k of all the thrusters from the control command T [c , k] by means of the sequence quadratic programming method; obtaining the thrust fk of all the thrusters by means of the quadratic programming method; and adding the thrust reduction coefficient p to a given objective function and part of formulas with constraint conditions. According to the thrust distributing method of the dynamic positioning system, the thrust and the azimuth angles of the thrusters can be calculated separately, and therefore errors and strange structures caused by linearization are avoided, and energy consumption of the thrusters is reduced.

Description

technical field [0001] The invention relates to a dynamic positioning system, in particular to a thrust distribution method of the dynamic positioning system. Background technique [0002] The Dynamic Positioning System (Dynamic Positioning System) is a computer-controlled closed-loop system that uses its own propeller system to automatically maintain the position and heading of the ship. It is mainly composed of a measurement system, a control system and a propeller system. Its function is: without the aid of the mooring system, it can automatically detect the deviation between the actual position of the ship and the target position, and combine the influence of external disturbance forces such as wind, waves, and currents to calculate the thrust and force required to restore the ship to the target position. The size of the torque, and distribute the thrust to each propeller, and then make each propeller generate corresponding thrust and torque, so that the ship can be kept...

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Problems solved by technology

However, the above-mentioned optimization problem under the above constraints is solved by using the sequential quadratic programming method, due to the addition of the singular value avoidance term

[0015] , thus, resulting in a large amount of calculation, moreover, linearization processing is often done in the algorithm, namely: s + B ( α 0 ) Δf + ∂ ∂ α ( B ( α ) f ) | α = α 0 f = f 0 · Δα = τ - B ( α 0 ) f 0 , which introduces an error

[0016] Since the above-mentioned thrust distribution algorithms have certain defects, which affect their application, these methods need to be improved to create an algorithm suitable for dynamic positioning system thrust distribution

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