Design of ship dynamic positioning auxiliary mooring system based on command filtering backstepping method

Abstract

The present invention provides a design method for a ship dynamic positioning assisted mooring system (DPAM) based on a command filter backstepping method. The system comprises a mooring system (1), a command filter controller (2), a thruster system (3), a position reference system (4), a sensor system (5), a DPAM ship (6), a finite time disturbance observer (7), a display and control computer (8), a guidance system (9), a tension sensor (10), etc. The present invention adopts the command filter backstepping method to design a controller, thereby avoiding the complex derivation operation process of the virtual control law and effectively improving the positioning accuracy of the ship dynamic positioning system. At the same time, a finite time estimation is made for the time-varying ocean environment disturbance with the help of a nonlinear finite time disturbance observer, so that the system can obtain a better control effect in the presence of external disturbance.

Description

Technical Field

[0001] The invention relates to the technical field of positioning control systems, and in particular to a ship dynamic positioning auxiliary mooring system based on a command filtering backstepping method. Background Art

[0002] With the continuous development of marine resources by humans, the operation area of ​​marine engineering has gradually advanced to offshore areas. At the same time, more stringent requirements have been put forward for the efficiency, safety, and automation of marine operations of ships. Due to the increase in seawater depth, the traditional anchoring positioning method can no longer meet the needs of marine operations, so dynamic positioning technology has emerged. The dynamic positioning system allows offshore platforms and ships to maintain the desired position or motion trajectory using only their own propulsion system when facing marine environmental interference (wind, waves, and currents). The dynamic positioning system is not affected by the depth of seawater, has strong flexibility, high positioning accuracy, and can operate in a variety of sea conditions. However, the dynamic positioning system needs to continuously consume fuel when working, and the cost is relatively high. In addition, the simple use of the dynamic positioning system in harsh sea conditions cannot achieve a good positioning effect. Therefore, a hybrid positioning method that combines anchoring positioning with dynamic positioning is one of the important research directions in the current field.

[0003] Chinese patent CN105929825A proposes a backstepping control method for ship dynamic positioning based on a neural dynamic model. This patent uses the backstepping method to design the control rate of the dynamic positioning control system, and effectively improves the control accuracy of the unmanned ship by defining variable errors and designing virtual control signals. Different from this method, the present invention uses the command filter backstepping method to design the controller under the premise of considering the external environmental interference and the dynamic characteristics of the ship's propeller, avoiding the complex derivation operation of the virtual control law. The mooring system and the nonlinear finite-time disturbance observer are combined with the designed controller, and the stability of the closed-loop system after integration is proved with the help of Lyapunov theory. Summary of the invention

[0004] 1. Purpose of the invention:

[0005] The purpose of the present invention is to design a ship dynamic positioning auxiliary anchoring system based on command filter backstepping method with good anti-interference ability, strong safety and high positioning accuracy. The purpose of the present invention is also to design a ship dynamic positioning auxiliary anchoring control method based on command filter backstepping method.

[0006] 2. Technical solution

[0007] The ship dynamic positioning auxiliary mooring system based on the command filter backstepping method of the present invention comprises a mooring system (1), a command filter controller (2), a thruster system (3), a position reference system (4), a sensor system (5), a DPAM ship (6), a finite time interference observer (7), a display and control computer (8), a guidance system (9), and a tension sensor (10). The characteristics are: the sensor system (5) collects the position and angle information of the DPAM ship (6) in real time, referred to as the posture information η, and transmits the collected posture information to the position reference system (4) and the display and control computer (8); the display and control computer (8) displays the actual posture signal of the ship in real time and transmits the expected posture step signal η d0 The guidance system (9) transmits the desired posture step signal η to the guidance system (9); d0 Processing is performed to obtain continuous desired posture information η d and its first and second order derivatives and transmitted to the command filter controller (2); the anchor cable of the mooring system (1) generates an anchoring force τ on the DPAM ship (6) m and transmitted to the finite time disturbance observer (7) through the tension sensor (10); the finite time disturbance observer (7) estimates the time-varying ocean environment disturbance to obtain the estimated value of the time-varying ocean environment disturbance And pass it to the command filter controller (2); the command filter controller (2) constructs a virtual signal β i and virtual control quantity α i , for the desired posture step signal η d Calculate and obtain each tracking error e i , construct error compensation signal θ 1 ,θ 2 ,θ 3 . And pass it to each tracking error compensation vector system output each tracking error compensation vector s 1 ,s 2 ,s 3 ; Time-varying ocean environment disturbance estimates and the virtual signal β i Perform command filtering control to obtain the control command τ of the propulsion system (3) c The propulsion system (3) receives the control command τ output by the command filter controller (2) c The DPAM ship (6) is controlled to move the ship to a desired position and heading.

[0008] 3. The ship auxiliary anchoring positioning control method based on the instruction filtering backstepping method of the present invention is:

[0009] (1) The sensor system (5) collects the position and angle information of the DPAM ship (6) in real time, referred to as the position information η, and transmits the collected position information to the position reference system and (4) the display and control computer (8);

[0010] (2) The display and control computer (8) displays the actual position and posture signal of the ship in real time and converts the expected position and posture step signal η d0 transmitted to the guidance system (9);

[0011] (3) Guidance system (9) responds to the desired posture step signal η d0 Processing is performed to obtain continuous desired posture information η d and its first and second order derivatives and transmitted to the mooring system (1) and the command filter controller (2);

[0012] (4) The anchor cable of the mooring system (1) generates an anchoring force τ on the DPAM vessel (6) m and transmitted to the finite time disturbance observer (7) via the tension sensor (10);

[0013] (5) Finite time disturbance observer (7) estimates the time-varying ocean environment disturbance and obtains the estimated value of the time-varying ocean environment disturbance And pass it to the command filter controller (2);

[0014] (6) Command filter controller (2) Construct virtual signal β i and virtual control quantity α i , for the desired posture step signal η d Calculate and obtain each tracking error e i . Construct error compensation signal θ 1 ,θ 2 ,θ 3 , and passed to each tracking error compensation vector system output each tracking error compensation vector s 1 ,s 2 ,s 3 ;

[0015] (7) Estimation of time-varying ocean environment disturbance and the virtual signal β i Perform command filtering control to obtain the control command τ of the propulsion system (3) c ;

[0016] (8) The propulsion system (3) generates a control command τ according to the output of the command filter controller (2) c The DPAM ship (6) is controlled to move the ship to a desired position and heading.

[0017] 4. The present invention can improve the anti-interference performance and positioning accuracy of the ship dynamic positioning system, and has high safety, and can achieve better control effects in the presence of external interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Earth coordinate system and ship coordinate system;

[0019] Figure 2 Anchor cable arrangement diagram of auxiliary mooring system;

[0020] Figure 3 System structure diagram; Specific implementation methods

[0021] The present invention will be described in more detail below in conjunction with the accompanying drawings.

[0022] The ship dynamic positioning auxiliary mooring system based on the command filter backstepping method of the present invention comprises a mooring system (1), a command filter controller (2), a thruster system (3), a position reference system (4), a sensor system (5), a DPAM ship (6), a finite time interference observer (7), a display and control computer (8), a guidance system (9), and a tension sensor (10). The sensor system (5) collects the position and angle information of the DPAM ship (6) in real time, referred to as the posture information η, and transmits the collected posture information to the position reference system (4) and the display and control computer (8); the display and control computer (8) displays the actual posture signal of the ship in real time and transmits the expected posture step signal η to the desired posture step signal η. d0 The guidance system (9) transmits the desired posture step signal η to the guidance system (9); d0 Processing is performed to obtain continuous desired posture information η d and its first and second order derivatives and transmitted to the command filter controller (2); the anchor cable of the mooring system (1) generates an anchoring force τ on the DPAM ship (6) m and transmitted to the finite time disturbance observer (7) through the tension sensor (10); the finite time disturbance observer (7) estimates the time-varying ocean environment disturbance to obtain the estimated value of the time-varying ocean environment disturbance And pass it to the command filter controller (2); the command filter controller (2) processes the desired posture information and its first-order and second-order derivatives Estimated value of pose information and its first-order and second-order derivatives and estimated value of time-varying ocean environment disturbance Perform command filtering control to obtain the control quantity τ of the propulsion system (3) c The propulsion system (3) controls the control quantity τ output by the command filter controller (2) c The DPAM ship (6) is controlled to move the ship to a desired position and heading.

[0023] The following is a more detailed description of the ship dynamic positioning auxiliary anchoring system based on the command filtering backstepping method of the present invention:

[0024] Establish the O-XY geodetic coordinate system shown in Figure (1) and O b -X b Y b Hull coordinate system. Considering the external environment interference and the dynamic characteristics of the ship propeller, the three-degree-of-freedom mathematical model of the dynamic positioning system is as follows:

[0025]

[0026] where η = [xyψ] T is the position and heading of the ship in the geodetic coordinate system; υ = [uvr] T is the velocity vector of the ship in the ship coordinate system; τ∈R 3 is the force and torque generated by the propulsion system; τ d ∈R 3 represents the vector consisting of the disturbance force and torque generated by wind, current and waves on the ship; τ m ∈R 3 represents the force generated by the mooring system; the matrix A∈R 3×3 and B∈R 3×3 is a diagonal matrix, τ c ∈R 3 is a control instruction; M∈R 3×3 is the inertial mass matrix; C(v)∈R 3×3 is the Coriolis and centripetal force matrix; D(v)∈R 3×3 is the damping matrix; R(ψ)∈R 3×3 is the rotation matrix, which is specifically expressed as:

[0027]

[0028] The guidance system (9) outputs the desired posture step signal η to the display and control computer d0 Processing is performed to obtain continuous desired posture information η d ∈R 3×1 and its first and second order derivatives And pass it to the mooring system and command filter controller. The mooring system uses Figure 2 The chain is laid in the manner shown, and the force and moment provided by the anchor cable are expressed as:

[0029]

[0030] In the formula, F i represents the horizontal tension of the i-th anchor cable; b i is the angle between the ith anchor cable and the X-axis in the geodetic coordinate system; (x i,y i ) represents the distance between the ship and the anchor fixed point decomposed in the hull coordinate system X b Axis and Y b The projection on the axis. The mooring force provided by the mooring system is expressed as:

[0031] τ m =[τ X τ Y τ Z ] T

[0032] The finite-time disturbance observer estimates the time-varying ocean environment disturbance, and its specific form is:

[0033]

[0034] in and are v and τ respectively d of the estimated value and The design is as follows:

[0035]

[0036] Where K 1 ∈R 3×3 and K 2 ∈R 3×3 is the positive definite diagonal observer gain matrix to be designed; function sig δ (·) is defined as sig σ (·)=|·| σ sign(·), sign is the sign function, 0<σ<1; Normal constant σ 1 and σ 2 Satisfy 0.5≤σ 1 <1 and σ 2 =2σ 1 -1.

[0037] In order to facilitate the design of the command filter controller, the ship model is transformed as follows: 1 =η,x 2 =R(ψ)v,x 3 =R(ψ)M -1 τ, τ d0 =R(ψ)M -1 (τ d +τ m ), Then the mathematical model of motion ((1)) becomes:

[0038]

[0039] in Define each tracking error as:

[0040] e 1 =x 1 -η d

[0041] e 2 =x 2 -α 1

[0042] e 3 =x 3 -α 2

[0043] Where η d is the desired attitude and heading; α 1 =[α 11 ,α 12 ,α 13 ] T , α 2 =[α 21 ,α 22 ,α 23 ] T It is the virtual control quantity generated by the command filter.

[0044] The compensation tracking error signal is defined as:

[0045] s 1 =e 1 -θ 1

[0046] s 2 =e 2 -θ 2

[0047] s 3 =e 3 -θ 3

[0048] The compensation signal θ i (i=(1),2,3) is defined as:

[0049]

[0050] Where L 1 , L 2 , L 3 is the number of positive definite diagonal matrices; g 1 =1, g 2 =1, Then construct the virtual controller through the backstepping method:

[0051]

[0052] The control law is τ c , Obtained by the finite-time disturbance observer; α 1 , and α 2 , The output of the filter is as follows:

[0053]

[0054] Where ζ is the filter damping ratio, ω n is the filter frequency.

Claims

1. A ship dynamic positioning auxiliary mooring system based on a command filter backstepping method, comprising a mooring system (1), a command filter controller (2), a thruster system (3), a position reference system (4), a sensor system (5), a DPAM ship (6), a finite time disturbance observer (7), a display and control computer (8), a guidance system (9), and a tension sensor (10); the system is characterized in that: the sensor system (5) collects the position and angle information of the DPAM ship (6) in real time, referred to as the position information η, and transmits the collected position information to the position reference system (4) and the display and control computer (8); the display and control computer (8) displays the actual position signal of the ship in real time and transmits the expected position step signal η d0 The guidance system (9) transmits the desired posture step signal η to the guidance system (9); d0 Processing is performed to obtain continuous desired posture information η d and its first and second order derivatives and transmitted to the command filter controller (2); the anchor cable of the mooring system (1) generates an anchoring force τ on the DPAM ship (6) m and transmitted to the finite time disturbance observer (7) through the tension sensor (10); the finite time disturbance observer (7) estimates the time-varying ocean environment disturbance to obtain the estimated value of the time-varying ocean environment disturbance And pass it to the command filter controller (2); the command filter controller (2) constructs a virtual signal β i and virtual control quantity α i , for the desired posture step signal η d Calculate and obtain each tracking error e i ; Construct error compensation signals θ1, θ2, θ3, and pass them to each tracking error compensation vector system output each tracking error compensation vector s1, s2, s3; Time-varying ocean environment interference estimation value and the virtual signal β i Perform command filtering control to obtain the control command τ of the propulsion system (3) c The propulsion system (3) receives the control command τ output by the command filter controller (2) c Controlling the DPAM ship (6) to move the ship to a desired position and heading; Taking into account the external environmental interference and the dynamic characteristics of the ship's propeller, the three-degree-of-freedom mathematical model of the dynamic positioning system is as follows: where η = [xyψ] T is the position and heading of the ship in the geodetic coordinate system; υ = [uvr] T is the velocity vector of the ship in the ship coordinate system; τ∈R 3 is the force and torque generated by the propulsion system; τ d ∈R 3 represents the vector consisting of the disturbance force and torque generated by wind, current and waves on the ship; τ m ∈R 3 represents the force generated by the mooring system; the matrix A∈R 3×3 and B∈R 3×3 is a diagonal matrix, τ c ∈R 3 is a control instruction; M∈R 3×3 is the inertial mass matrix; C(v)∈R 3×3 is the Coriolis and centripetal force matrix; D(v)∈R 3×3 is the damping matrix; R(ψ)∈R 3×3 is the rotation matrix, which is specifically expressed as: The force and moment provided by the anchor cable of the mooring system are expressed as: In the formula, F i represents the horizontal tension of the i-th anchor cable; b i is the angle between the ith anchor cable and the X-axis in the geodetic coordinate system; (x i ,y i ) represents the distance between the ship and the anchor fixed point decomposed in the hull coordinate system X b Axis and Y b Projected onto the axis, the mooring force provided by the mooring system is expressed as: t m =[τ X t Y t Z ] T The specific form of the finite-time disturbance observer is: in and are v and τ respectively d of the estimated value and Designed as follows where K1∈R 3×3 and K2∈R 3×3 is the positive definite diagonal observer gain matrix to be designed; function sig δ (·) is defined as sig σ (·)=|·| σ sign(·), sign is the sign function, 0<σ<1; The positive constants σ1 and σ2 satisfy 0.5≤σ1<1 and σ2=2σ1-1; Define each tracking error as: e1=x1-η d e2=x2-α1 e3=x3-α2 Where η d is the desired position and heading; x1 = η, x2 = R(ψ)v, x3 = R(ψ)M -1 τ,α1=[α 11 ,α 12 ,α 13 ] T , α2=[α 21 ,α 22 ,α 23 ] T It is the virtual control quantity generated by the command filter; The compensation tracking error signal is defined as: s1 = e1-θ1 s2=e2-θ2 s3=e3-θ3 The compensation signal θ i (i=1,2,3) is defined as: Where L1, L2, L3 are positive definite diagonal arrays; g1 = 1, g2 = 1, Then construct the virtual controller through the backstepping method: in, The control law is τ c , Obtained by the finite-time disturbance observer; α1, and α2, The output of the filter is as follows: Where ζ is the filter damping ratio, ω n is the filter frequency.

2. A control method for a ship dynamic positioning auxiliary mooring system based on the instruction filtering backstepping method according to claim 1, characterized in that: (1) The sensor system (5) collects the position and angle information of the DPAM ship (6) in real time, referred to as the position information η, and transmits the collected position information to the position display control computer (8) and the position reference system (4); (2) The display and control computer (8) displays the actual position and posture signal of the ship in real time and converts the expected position and posture step signal η d0 transmitted to the guidance system (9); (3) Guidance system (9) responds to the desired posture step signal η d0 Processing is performed to obtain continuous desired posture information η d and its first and second order derivatives and transmitted to the mooring system (1) and the command filter controller (2); (4) The anchor cable of the mooring system (1) generates an anchoring force τ on the DPAM vessel (6) m and transmitted to the finite time disturbance observer (7) via the tension sensor (10); (5) Finite time disturbance observer (7) estimates the time-varying ocean environment disturbance and obtains the estimated value of the time-varying ocean environment disturbance And pass it to the command filter controller (2); (6) Command filter controller (2) Construct virtual signal β i and virtual control quantity α i , for the desired posture step signal η d Calculate and obtain each tracking error e i ; Construct error compensation signals θ1, θ2, θ3, and transmit them to each tracking error compensation vector system to output each tracking error compensation vector s1, s2, s3; (7) Estimation of time-varying ocean environment disturbance and the virtual signal β i Perform command filtering control to obtain the control command τ of the propulsion system (3) c ; (8) The propulsion system (3) generates a control command τ according to the output of the command filter controller (2) c The DPAM ship (6) is controlled to move the ship to a desired position and heading.

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