Ship intelligent navigation and dynamic positioning thrust allocation method based on global search

Abstract

A ship (1) intelligent navigation and dynamic positioning thrust allocation method based on global search, comprising: a thrust allocation program determining a received demand force, and using an optimization algorithm to search a full domain, which does not consider the response speeds of propellers (2, 3, 4), for an optimal allocation scheme; if there is no feasible allocation scheme, reducing the demand force in an equal proportion to serve as a new demand force so as to be brought into calculation until a demand within a ship capability range is satisfied; and on the basis of a final demand force, using the optimization algorithm to calculate an optimal allocation scheme within a full domain of executable quantities of the propellers (2, 3, 4), so as to obtain forces f1xd, f1yd, f2xd, f2yd, …, fmxd, and fmyd generated by each propeller (2, 3, 4) in the longitudinal direction and the transverse direction of a ship body, wherein m is the number of propellers (2, 3, 4), and fixd and fiyd respectively are forces expected to be generated by an ith propeller (2, 3, 4) in the longitudinal direction and the transverse direction.

Description

Ship intelligent navigation and dynamic positioning thrust allocation method based on global search TECHNICAL FIELD

[0001] The present application relates to the field of intelligent navigation and ship dynamic positioning, and particularly relates to a ship intelligent navigation and dynamic positioning thrust allocation method based on global search. BACKGROUND

[0002] Thrust system has been the key of many autonomous navigation and dynamic positioning ship operations, especially in deep water production facilities, which can ensure the required position and heading of the ship under the environmental interference of wind, wave, current, etc. The thrust allocation algorithm is the core component of the thrust system, which plays an important role in improving the control accuracy, operation stability and operation flexibility of the ship during the sea operation and navigation. The traditional thrust allocation optimization algorithm runs with fixed steps per second, and only focuses on the limited change range of the thruster state in a short time. This algorithm lacks sufficient consideration of the slow dynamic characteristics of the thruster, which often leads to low energy efficiency of the ship, and also cannot exert the maximum capacity of the thruster.

[0003] SUMMARY

[0004] In view of the above problems, the present application provides an intelligent navigation and dynamic positioning thrust allocation method with thruster operation range global search capability. The method can reasonably allocate the thrust of the thruster according to the results of global search and the current state of the thruster, and has the characteristics of simple and efficient, fast response speed, low energy consumption and strong maneuverability.

[0005] The present application is implemented by the following technical solutions:

[0006] A ship intelligent navigation and dynamic positioning thrust allocation method based on global search, the controller of the ship transmits the demand force τ desire =[τ x ,τ y ,τ n ] of the longitudinal, lateral and turning direction of the ship to the ship thrust allocation module, the thrust allocation program judges the received demand force, searches the optimal allocation scheme in the global domain without considering the response speed of the thruster by using the optimization algorithm; if there is no feasible allocation scheme, the demand force is reduced by λ, 0 < λ < 1 times as a new demand force, until the demand force is within the ship capacity; according to the final demand force, the optimal allocation scheme is calculated in the global domain of the thruster executable amount by using the optimization algorithm, and the force f 1xd , f 1yd , f 2xd , f 2yd ,..., f mxd , f myd, where m is the number of thrusters, f ixd , and f iyd are the forces expected to be generated by the i-th thruster in the longitudinal and lateral directions, respectively.

[0007] Furthermore, the expected execution amount x is obtained based on the mapping relationship between the force generated by each propeller in the longitudinal and transverse directions of the hull and the propeller execution amount. 1d , x 2d ,...,x nd , where x 1d , x 2d ,...,x nd They are respectively the speed of the bow thruster, the propeller speed of the left rudder propeller, the rudder angle of the left rudder propeller, the propeller speed of the right rudder propeller, the rudder angle of the right rudder propeller..., and the rudder angle of the nth rudder propeller.

[0008] Furthermore, the current thruster execution amount x 1c , x 2c ,...,x nc and the rate of change of each thruster v1, v2, ..., v n Get the time t1, t2, ..., t required for the current propeller to go from the current execution amount to the expected execution amount n , the maximum value is the maximum time t required from the current value to the expected value max , where x 1c , x 2c ,...,x nc They are respectively the current speed of the bow thruster, the current speed of the propeller of the left rudder propeller, the current rudder angle of the left rudder propeller, the current speed of the propeller of the right rudder propeller, the current rudder angle of the right rudder propeller, and so on, and the current rudder angle of the nth rudder propeller.

[0009] Furthermore, if the maximum time t max Less than the period t of the controller issuing the control command interval , the next cycle thruster can achieve the thruster's expected execution amount x 1d , x 2d ,...,x nd , otherwise the execution amount of the thruster is expressed as x next =[x 1next , x 2next ,...,x nnext ], where x inext =(x id -x ic )*t interval / t max +x ic , is the thruster execution amount of the thruster's i-th degree of freedom in the next cycle.

[0010] Further, the relationship between the execution amount and the thrust of the thruster is performed to obtain the generated force f of the thruster in the longitudinal direction and the lateral direction 1xnext f 1ynext , f 2xnext , f 2ynext ,..., f mxnext , f mynext , and finally synthesize the force τ of the ship body in the next period next =[τ xnext , τ ynext , τ nnext ].

[0011] The beneficial effects of the present application are:

[0012] The ship intelligent navigation and dynamic positioning thrust distribution method based on global search of the present application is used for thrust distribution of the ship intelligent navigation and dynamic positioning system, converts the demand force of the ship into the execution amount of each thruster, and has the advantages of fast thruster response speed, low energy consumption, and high maneuverability. BRIEF DESCRIPTION OF DRAWINGS

[0013] Fig. 1 is a flow chart of the ship intelligent navigation and dynamic positioning thrust distribution method based on global search of the present application;

[0014] Fig. 2 is a thruster configuration of an intelligent navigation and dynamic positioning ship in an embodiment of the present application;

[0015] In the figure: 1. Intelligent navigation and dynamic positioning ship, 2. Side thrust thruster, 3. Left rudder propeller thruster, 4. Right rudder propeller thruster. DETAILED DESCRIPTION

[0016] The present application will be described in detail below in combination with the drawings and specific embodiments. The present embodiment is implemented on the premise of the technical solution of the present application, and detailed implementation modes and specific operation processes are given, but the protection scope of the present application is not limited to the following embodiments.

[0017] As shown in Figs. 1 and 2, the ship intelligent navigation and dynamic positioning thrust distribution method based on global search of the present application installs three sets of thruster devices in the intelligent navigation and dynamic positioning ship 1, which are respectively the bow side thrust thruster 2, the left rudder propeller thruster 3, and the right rudder propeller thruster 4. When the controller issues the demand force τ of the ship in the longitudinal direction, the lateral direction, and the turning bow direction desire =[τ x , τ y , τ n ]. An optimal distribution scheme is searched in the global domain without considering the response speed of the thruster by using an optimization algorithm. If there is no distribution result, it is proportionally reduced until there is an optimal solution [f 1xd , f1yd , f 2xd , f 2yd , f 3xd , f 3yd ] where f 1xd , f 1yd , f 2xd , f 2yd , f 3xd , f 3yd are the longitudinal and lateral forces generated by the bow thruster 2, the port side propeller 3, and the starboard side propeller 4 respectively. The desired forces generated by the thrusters are mapped to the desired actuation quantities [x 1d , x 2d , x 3d , x 4d , x 5d ] where x 1d , x 2d , x 3d , x 4d , x 5d are the rotational speed of the bow thruster 2, the rotational speed of the propeller of the port side propeller 3, the rudder angle of the port side propeller 3, the rotational speed of the propeller of the starboard side propeller 4, and the rudder angle of the starboard side propeller 4 respectively. The time [t1, t2, t3, t4, t5] required to change from the current values to the desired values is obtained based on the current rotational speed of the bow thruster 2 x 1c , the current rotational speed of the propeller of the port side propeller 3 x 2c , the current rudder angle of the port side propeller 3 x 3c , the current rotational speed of the propeller of the starboard side propeller 4 x 4c , the current rudder angle of the starboard side propeller 4 x 5c and the rate of change of the rotational speed of the bow thruster 2 v1, the rate of change of the rotational speed of the propeller of the port side propeller 3 v2, the rate of change of the rudder angle of the port side propeller 3 v3, the rate of change of the rotational speed of the propeller of the starboard side propeller 4 v4, and the rate of change of the rudder angle of the starboard side propeller 4 v5, where the maximum time required is t max . The period at which the controller issues control commands is t interval , if t max is less than t interval then the next period the thrusters can reach the desired actuation quantities [x 1d , x 2d , x 3d , x 4d , x 5d , otherwise the i-th actuation quantity of the thrusters can be expressed as x inext = (x id - x ic )*t interval / t max + x icThe forces generated by the propellers in different directions [f 1xnext , f 1ynext , f 2xnext , f 2ynext , f 3xnext , f 3ynext ] are obtained by the relationship between the executed quantity and the thrust emitted by the propeller. Finally, the forces τ next = [τ xnext , τ ynext , τ nnext ] on the hull for the next period are synthesized according to the position of the propellers in the hull.

[0018] The above-described embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the scope of the patent right of the present application. It should be pointed out that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent right of the present application should be subject to the appended claims.

Claims

1. A global search based intelligent sailing and dynamic positioning thrust allocation method for a ship, characterized in that: The controller of the ship sends the demand forces of the ship in longitudinal, lateral and turning directions to the ship thrust distribution module desire = [τ x , τ y , τ n ] to the thrust distribution program, which judges the received demand forces and searches for the optimal distribution scheme in the whole domain without considering the response speed of the propeller by using an optimization algorithm; If no feasible allocation is found, the demand forces are scaled down by a factor λ, 0 < λ < 1, and the calculation is repeated until a solution is found within the ship's capacity constraints. According to the final demand force, the optimal distribution scheme is calculated in the whole domain of the propeller executable amount by using the optimization algorithm, to obtain the force f generated by each propeller in the longitudinal and transverse direction of the ship body 1xd , f 1yd , f 2xd , f 2yd ,..., f mxd , f myd , wherein m is the number of propellers, f ixd , and f iyd are the longitudinal and transverse forces respectively expected to be generated by the i-th propeller.

2. The global search based intelligent sailing and dynamic positioning thrust allocation method for a ship according to claim 1, characterized in that: The desired execution amount x is obtained from a mapping between the force and the execution amount of each propeller in the longitudinal and lateral directions of the hull 1d , x 2d ,..., x nd , where x 1d , x 2d ,..., x nd are the rotation speed of the bow thruster, the rotation speed of the left rudder propeller, the rudder angle of the left rudder propeller, the rotation speed of the right rudder propeller, the rudder angle of the right rudder propeller,..., the rudder angle of the n-th rudder propeller, respectively.

3. The global search based intelligent sailing and dynamic positioning thrust allocation method for a ship according to claim 2, characterized in that: The execution amount x of the current thruster 1c , x 2c ,...,x nc and the rate of change of each thruster v1, v2, ..., v n Get the time t1, t2, ..., t required for the current propeller to go from the current execution amount to the expected execution amount n , the maximum value is the maximum time t required from the current value to the expected value max , where x 1c , x 2c ,...,x nc They are respectively the current speed of the bow thruster, the current speed of the propeller of the left rudder propeller, the current rudder angle of the left rudder propeller, the current speed of the propeller of the right rudder propeller, the current rudder angle of the right rudder propeller, and so on, and the current rudder angle of the nth rudder propeller.

4. The global search based intelligent sailing and dynamic positioning thrust allocation method for a ship according to claim 3, characterized in that: If the maximum time t max Less than the period t of the controller issuing the control command interval , the next cycle thruster can achieve the thruster's expected execution amount x 1d , x 2d ,...,x nd , otherwise the execution amount of the thruster is expressed as x next =[x 1next , x 2next ,...,x nnext ], where x inext =(x id -x ic )*t interval / t max +x ic , is the thruster execution amount of the thruster's i-th degree of freedom in the next cycle.

5. The global search based intelligent sailing and dynamic positioning thrust allocation method for a ship according to claim 1, characterized in that: The forces generated by the propellers in the longitudinal and transversal directions f are obtained by performing the relationship between the executed quantities and the thrust issued by the propellers 1xnext , f 1ynext , f 2xnext , f 2ynext ,..., f mxnext , f mynext , the final synthesis of the forces τ on the hull for the next period next = [τ xnext , τ ynext , τ nnext ].

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