Unmanned ship docking control method based on omnidirectional beacon distance measuring device

Abstract

The invention discloses an unmanned ship docking control method based on an omnidirectional beacon distance measuring device, and relates to the technical field of intelligent ship motion control. The invention aims to solve the problems of low positioning precision, complex calculation process and large calculation amount in the traditional MEMS inertial navigation positioning technology. According to the unmanned ship docking control method based on the omni-directional beacon distance measuring device, the relative tracking error of the docking ship and the target ship in the north-east coordinate system is calculated according to the omni-directional beacon distance measuring device, and a basis is provided for subsequent docking navigation control. In order to ensure that a docking ship can move to an expected docking point from an initial position, PID related control is adopted for docking navigation control, and it can be ensured that the control process is free of overshoot and can be carried out stably as much as possible. The thrust of the thruster is distributed, it is guaranteed that the whole combined state formed through butt joint can move cooperatively, and energy consumption is low.

Description

Technical Field

[0001] The present invention belongs to the technical field of intelligent ship motion control. Background Art

[0002] With the continuous improvement and perfection of technologies such as computers, artificial intelligence, and big data computing, reliable software and hardware technical guarantees and theoretical supports are provided for ship positioning control research. At the same time, theoretical research and practical applications around ship docking are becoming more and more extensive. Among them, the precise measurement and accurate control of the relative position between ships during the docking process are the key issues to be solved first in intelligent ship docking research.

[0003] Since the ship docking process is a delicate and complex ocean engineering operation, problems such as misalignment of docking positions and mutual influence between docking ships will inevitably occur during the docking process. Therefore, achieving precise positioning of the position during the docking process is a huge challenge for efficient docking. The main reasons are as follows: The docking process is a gradual process. Ship individuals approach and then join together in the required combined state form in sequence. If the position positioning of a single ship is not precise enough, as the docking process progresses, the position error of the overall combined state will increase exponentially, and in the worst case, it will lead to the failure of the overall combined state structure and cause a collision accident.

[0004] Traditional positioning technologies, such as the MEMS inertial navigation positioning system, are navigation parameter calculation systems with gyroscopes and accelerometers as sensitive devices. This system establishes a navigation coordinate system based on the output of the gyroscope and calculates the speed and position of the vehicle in the navigation coordinate system based on the output of the accelerometer. The inertial navigation system belongs to the dead reckoning navigation method, that is, the position of the next point is deduced from the position of a known point based on the continuously measured course angle and speed of the moving object. The positioning accuracy of this system is about 1m. If the MEMS inertial navigation positioning system is used to determine the position of a ship, the target ship and the docking ship need to position their respective positions, and then carry out docking control based on the deduced positions. In this process, due to the low positioning accuracy, the deviation between the deduced position and the actual position may be relatively large, which may lead to docking failure. Summary of the Invention

[0005] The present invention is to solve the problems of low positioning accuracy, complex calculation process, and large calculation amount existing in the traditional MEMS inertial navigation positioning technology. To solve this problem, the present invention proposes an unmanned boat docking control method based on an omnidirectional beacon ranging device. This method uses the relative position information between two ships for docking control, and the relative position information can be obtained by calculating the relevant trigonometric function values of the beacon measurement distance values. The positioning accuracy reaches the centimeter level, which further ensures that the docking process is completed reasonably and precisely.

[0006] An unmanned boat docking control method based on an omnidirectional beacon ranging device, comprising:

[0007] Calculating the relative tracking error between the docking boat and the target boat in the north-east coordinate system by using the omnidirectional beacon ranging device;

[0008] Calculating the control rates of the docking boat and the target boat by using the relative tracking error:

[0009]

[0010] where τ A and τ T are the control rates of the docking boat and the target boat respectively, E AT is the relative tracking error between the docking boat and the target boat in the north-east coordinate system, K p is the proportionality coefficient, K i is the differential coefficient, K d is the integral coefficient, τ surge is the longitudinal input, τ sway is the lateral input, τ yaw is the yaw input;

[0011] Allocating the control rates of the two thrusters on each boat respectively according to the control rates of the docking boat and the target boat to achieve unmanned boat docking control.

[0012] Further, the above-mentioned calculating the relative tracking error between the docking boat and the target boat in the north-east coordinate system by using the omnidirectional beacon ranging device includes:

[0013] Assume that the position points of the omnidirectional beacon ranging devices installed at the bow, stern and center of gravity of the target boat are B, C and Q respectively, and the position points of the omnidirectional beacon ranging devices installed at the bow, stern and center of gravity of the docking boat are M, N and P respectively. Draw a perpendicular line from M to the BC side with the foot of the perpendicular being G, and draw a perpendicular line from point P to the BC and extend it to intersect the reverse extension line of the x-axis at point K;

[0014] The relative tracking error E AT_1 between the docking boat and the target boat during the long-distance docking process is:

[0015]

[0016] where R qp is the distance between the position points Q and P, ∠θ1 = ∠CPQ + ∠KPC,

[0017] W x and W y are the longitudinal docking safety distance and the lateral docking safety distance respectively;

[0018] The relative tracking error E during the close-range lateral docking process between the docking ship and the target ship AT_2 is:

[0019]

[0020] ∠θ2 = ∠CPQ - ∠KPC;

[0021] The relative tracking error E during the close-range longitudinal docking process between the docking ship and the target ship AT_3 is:

[0022]

[0023] wherein,

[0024] Furthermore, the control rates of the two thrusters on each ship are allocated according to the control rates of the docking ship and the target ship respectively, including:

[0025] The control rate can be expressed as:

[0026] τ ζ = T ζ (δ)T ζ ,

[0027] where ζ = A, T, T ζ represents the thruster control thrust vector and has T ζ = [T ζ1 , T ζ2 T , T ζ1 and T ζ2 respectively represent the thrusts of the two thrusters on the ship ζ, and T ζ (δ) represents the thruster structure matrix and has T ζ (δ) = [γ ζ1 , γ ζ2 ,

[0028]

[0029] i = 1, 2, δ ζi represents the swing angle of the i-th thruster, and l xi and l yi respectively represent the longitudinal and lateral positions of the i-th thruster on the ship where it is located;

[0030] The control rates of the two thrusters are allocated according to the control objective function and its constraints.

[0031] Furthermore, the expression of the above control objective function is as follows:

[0032] ​

[0033] where s ζ is the compensation factor, and both P and Q are constant quadratic matrices.

[0034] Furthermore, the constraint conditions of the above control objective function are:

[0035] Equality constraint:

[0036] τ ζ = T ζ (δ)T ζ + s ζ ;

[0037] Inequality constraint:

[0038]

[0039] where and are the lower and upper limits of T ζi respectively, and are the lower and upper limits of δ ζi respectively, and are the lower and upper limits of ΔT ζi respectively, and are the lower and upper limits of Δδ ζi respectively, and ΔT ζi and Δδ ζi represent the change rates of the thrust and swing angle of the i-th thruster of the ship respectively.

[0040] Furthermore, the expressions of the above constant quadratic matrices P and Q are:

[0041]

[0042] Furthermore, the specific values of the above inequality constraints are as follows:

[0043]

[0044] Furthermore, the above longitudinal input τ surge and the lateral input τ sway are 0.8 and 0 respectively.

[0045] The present invention aims at the problems of precise positioning and docking control in the docking process of ship combined state control, and proposes the advantages of the ranging docking control method using the omnidirectional beacon ranging device compared with the prior art:

[0046] (1) The present invention uses an omnidirectional beacon ranging device. Compared with traditional positioning devices, the beacon ranging device can directly obtain the relative distance between two ranging devices, and thus can directly obtain the relative distance information at the ranging devices of two ships. Accordingly, it can skillfully reduce the error of calculating the relative distance in the traditional positioning method, thereby ensuring more accurate relative position information.

[0047] (2) According to the current relevant research work, there are often problems in existing research such as low position positioning accuracy, which leads to poor docking effects. The beacon ranging device used in the present invention, especially for short-distance positioning, improves the positioning accuracy of position information to the centimeter level, which has great advantages. This not only ensures the accuracy of positioning, but also greatly reduces the oscillation problems generated during the short-distance docking process, enabling the docking process to proceed smoothly and accurately.

[0048] (3) Based on the relative distance solved by the omnidirectional beacon, a docking control scheme based on relative error was studied, and at the same time, a method of thrust optimization was adopted, which not only improved the accuracy of docking control but also improved the efficiency of the docking process, realizing a green docking control process at sea.

[0049] The present invention can ensure the precise positioning and accurate control of the relative position of the unmanned boat during the docking process, minimize the docking error as much as possible, and ensure the smooth progress of the docking control task. The present invention is applicable to the key problem that the docking error is large during the overall motion control process of multi-ship docking in the ocean operation process, which may cause docking failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 Schematic diagram of measurement by a long-distance docking ranging device;

[0051] Figure 2 Schematic diagram of measurement by a short-distance lateral docking ranging device;

[0052] Figure 3 Schematic diagram of measurement by a short-distance longitudinal docking ranging device;

[0053] Figure 4 Curve graph of the change of the docking safety distance between two ships;

[0054] Figure 5 Trajectory graph of the docking process of two ships;

[0055] Figure 6 Flowchart of a method for controlling the docking of an unmanned boat based on an omnidirectional beacon ranging device. DETAILED DESCRIPTION OF THE INVENTION

[0056] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0057] Aiming at the problems of low accuracy, complex calculation process and large calculation amount existing in the positioning accuracy of traditional MEMS inertial navigation and positioning technology, this embodiment proposes a relative position docking control method using an omnidirectional beacon ranging device. Refer to FIG. Figures 1 to 6 Specifically describing this embodiment, an unmanned boat docking control method based on an omnidirectional beacon ranging device described in this embodiment includes:

[0058] First, calculate the relative tracking error between the docking boat and the target boat in the north-east coordinate system according to the omnidirectional beacon ranging device, providing a basis for the subsequent docking navigation control. Secondly, in order to ensure that the docking boat can move from the initial position to the desired docking point, PID-related control is used for docking navigation control, which can ensure that the control process has no overshoot and proceeds smoothly as much as possible. Finally, distribute the thrust of the thruster to ensure that the overall combined state formed by docking can move synergistically and consume less energy. The specific implementation steps are as follows:

[0059] The first step: Calculate the relative tracking error E between the docking boat and the target boat in the north-east coordinate system AT .

[0060] It is known that the ship widths of the target boat T and the docking boat A are d T and d A , and the ship lengths are l T and l A .

[0061] Suppose there are three beacon ranging devices on the target boat T, where the device on one side of the bow is B, the device on one side of the stern is C, and the device at the center of gravity of the ship is Q. There are three beacon ranging devices on the docking boat A, where the device on one side of the bow is M, the device on one side of the stern is N, and the device at the center of gravity of the ship is P. The installation position information of the devices is known (for example, the distance between two devices). Using the six devices on the two ships, the following data can be measured:

[0062] The relative distances R qm , R qn and R qp of the device Q relative to the devices M, N and P;

[0063] The relative distances R of the device B relative to the devices M, N and Pbm , R bn and R bp ;

[0064] The relative distances R cm , R cn and R cp .

[0065] Use the cosine theorem and inverse cosine theorem of a triangle to calculate the required angles. The calculation principle and specific process are as follows:

[0066] According to the cosine theorem of a triangle, it can be known that:

[0067]

[0068] According to the inverse cosine theorem, it can be known that:

[0069]

[0070] According to the different initial positions and docking methods of the docking ship, the relative error calculation can be divided into the following three scenarios.

[0071] (1) Scenario 1: The relative tracking error E AT_1 of the docking ship and the target ship in the north-east coordinate system during the long-distance docking process, as Figure 1 shown.

[0072] On the premise that the required angle information is known, extend MN along the bow direction, draw a parallel line of BC through point M, and at the same time draw a perpendicular line from point M to side BC, with the foot of the perpendicular being G. According to the angle relationship, it can be obtained that:

[0073]

[0074] Draw a perpendicular line from point P to BC and intersect the reverse extension line of the x-axis at point K. From the angle relationship, it can be obtained that:

[0075] So ∠KPC = ∠BCP - 90°.

[0076] Since ∠θ1 = ∠CPQ + ∠KPC, the coordinates of point P relative to point Q (i.e., the coordinate origin O) can be obtained:

[0077]

[0078] To sum up, the relative tracking error E AT_1 of the docking ship and the target ship in the north-east coordinate system during the long-distance docking process is:

[0079]

[0080] where W x and Wy They are all normal constants, representing the longitudinal docking safety distance and the lateral docking safety distance respectively.

[0081] (2)Scenario 2: The relative tracking error E between the docking ship and the target ship in the north-east coordinate system during the close-range lateral docking AT_2 , as Figure 2 shown.

[0082] On the premise that the required angle information is known, extend MN along the bow direction, draw a parallel line of BC through point M, and at the same time draw a perpendicular line from point M to side BC, with the foot of the perpendicular being G. According to the angle relationship, we can get:

[0083]

[0084] Draw a perpendicular line from point P to BC and intersect the reverse extension line of the x-axis at point K. From the angle relationship, we can get:

[0085] ∠KPC = 90° - ∠BCP.

[0086] Since ∠θ2 = ∠CPQ - ∠KPC, the coordinates of point P relative to point Q (i.e., the coordinate origin O) can be obtained:

[0087]

[0088] To sum up, the relative tracking error E between the docking ship and the target ship in the north-east coordinate system during the close-range lateral docking AT_2 is:

[0089]

[0090] (3)Scenario 3: The relative tracking error E between the docking ship and the target ship in the north-east coordinate system during the close-range longitudinal docking AT_3 , as Figure 3 shown.

[0091] On the premise that the required angle information is known, extend MN along the bow direction, draw a parallel line of BC through point M, and at the same time draw a perpendicular line from point M to side BC, with the foot of the perpendicular being G. According to the angle relationship, we can get:

[0092]

[0093] Draw a perpendicular line from point P to BC and intersect the reverse extension line of the x-axis at point K. From the angle relationship, we can get:

[0094] ∠KPC + 90° = ∠BCP,

[0095] According to the exterior angle theorem of a triangle, we have:

[0096] ∠KPC = ∠BCP - 90°.

[0097] Since ∠θ1 = ∠CPQ + ∠KPC, the coordinates of point P relative to point Q (i.e., the coordinate origin O) can be obtained:

[0098]

[0099] In summary, during the close-range longitudinal docking process, the relative tracking error E between the docking ship and the target ship in the north-east coordinate system AT_3 :

[0100]

[0101] In the second step, based on the calculated relative error, relevant docking controllers are designed.

[0102] Define the subscript A to represent the docking ship, T to represent the target ship, and N to represent the north-east coordinate system.

[0103] The trajectory of the docking ship in the north-east coordinate system is:

[0104] The trajectory of the target ship in the north-east coordinate system is:

[0105] where n and e represent the abscissa and ordinate of the actual position of the ship, represents the actual heading angle of the ship.

[0106] Since the two ships perform the mutual docking movement process, the motion models of the two ships are given as follows:

[0107]

[0108] where ζ = A, T, represents the first derivative of η ζN , is the first derivative of υ ζ , υ ζ represents the velocity vector of the ship in the body coordinate system, represents the transformation matrix between the north-east coordinate system and the body coordinate system, τ ζ is the ship control input vector, and ω is the ocean environmental disturbance vector acting on the ship.

[0109] M is the inertia matrix, and there is

[0110] D is the damping coefficient matrix, and there is

[0111] Based on the motion model, taking the tracking error measured by the docking beacon as the feedback quantity, control the docking ship and the target ship to move from the initial states η AN0 and η TN0 in the north-east coordinate system to the desired docking point, and try to ensure that there is no overshoot in the control process.

[0112] The control law is as follows:

[0113]

[0114] Among them, τ A and τ T are the control rates of the docking ship and the target ship respectively, E AT is the relative tracking error between the docking ship and the target ship in the north-east coordinate system, K p is the proportional coefficient, K i is the differential coefficient, K d is the integral coefficient, τ surge is the longitudinal input (with a value of 0.8), τ sway is the lateral input (with a value of 0), τ yaw is the yaw input.

[0115] In the third step, the thrust of the actuator is allocated to complete the docking process.

[0116] Ship control input vector model:

[0117] τ ζ = T ζ (δ)T ζ ,

[0118] Among them, represents the thruster control thrust vector, and there is T ζ = [T ζ1 , T ζ2 T , T ζ1 and T ζ2 represent the thrusts of the two thrusters on the ship ζ respectively.

[0119] represents the thruster structure matrix, which is defined by a set of column vectors (i = 1, 2), that is, T ζ (δ) = [γ ζ1 , γ ζ2 ζi The type structure of γ

[0120]

[0121] Among them, δ i represents the swing angle of the i-th thruster, l xi and l yi represent the longitudinal and lateral positions of the i-th thruster on the ship where it is located respectively.

[0122] The thrust allocation optimization process is as follows:

[0123] ​​(1) Establish the objective function

[0124]

[0125] Where: represents the compensation factor, and the constant quadratic form matrix

[0126] (2) Constraint conditions

[0127] (i) Equality constraint:

[0128] τ ζ = T ζ (δ)T ζ + s ζ .

[0129] (ii) Inequality constraint:

[0130]

[0131] Where: ΔT ζi and Δδ ζi represent the change rates of the propeller thrust and the swing angle of two ships respectively.

[0132] In this embodiment,

[0133] Fourthly, design relevant numerical simulation experiments.

[0134] Under ideal conditions, the simulation conditions are set as the initial position of the target ship [0, 0, 0] T and the initial velocity [0.5, 0, 0] T , the initial position of the docking ship [-10, -10, -10°] T and the initial velocity [0.5, 0, 0] T , the simulation step size is 1 s, and the docking safety distance is set as a time-varying distance: W = 10 + (3 - 10) / {1 + exp[-0.015*(t - 600)]}, with the unit of m, and its variation is as Figure 4 shown. The simulation results of the lateral docking of two ships in the north-east coordinate system are as Figure 5 shown.

[0135] Through Matlab simulation, it is proved that the proposed positioning method using the beacon ranging device can use the north-east coordinate system of the target ship as the reference coordinate system to obtain more accurate relative position information and heading information of the docking ship in this reference coordinate system, ensuring the accuracy of the position during the docking process, and thus ensuring the smooth progress of the docking control process. At the same time, the simulation results verify the effectiveness and accuracy of the docking control method, that is, the proposed docking control method using the beacon ranging device can effectively reduce the relative tracking information error during the docking process, and at the same time ensure a high degree of accuracy even during close-range docking, thus enabling the docking process to proceed smoothly and efficiently.

[0136] In summary, the unmanned boat docking control method based on the omnidirectional beacon ranging device described in this embodiment improves the positioning accuracy and control accuracy of the ship, and this embodiment only needs to use the trigonometric functions of relevant measurement values to achieve, greatly simplifying the calculation process and significantly reducing the amount of calculation. In addition, by installing beacon ranging devices at different positions on the hulls of the target ship and the docking ship, according to the relative distance information fed back by the ranging devices, the relative tracking error between the two ships in the north-east coordinate system can be obtained using trigonometric functions, and then the docking navigation control can be executed.

[0137] Through verification: the proposed ranging method greatly improves the ranging accuracy. Compared with the positioning accuracy of about 1m of the traditional MEMS inertial navigation positioning technology, this method improves the positioning accuracy to the centimeter level, making the hull docking process, especially the close-range docking control process, more accurate and efficient.

[0138] Although the present invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed, as long as they do not deviate from the spirit and scope of the present invention as defined by the appended claims. It should be understood that different dependent claims and the features described herein can be combined in a manner different from that described in the original claims. It should also be understood that the features described in connection with a single embodiment can be used in other described embodiments.

Claims

1. A method for controlling docking of an unmanned boat based on an omnidirectional beacon ranging device, characterized in that: include: The relative tracking error between the docking ship and the target ship in the north-east coordinate system is calculated using the omnidirectional beacon ranging device. The control rate of the docking ship and the target ship is calculated using the relative tracking error: Among them, τ A and τ T are the control rates of docking ship and target ship, E AT is the relative tracking error between the docking ship and the target ship in the northeast coordinate system, K p is the proportionality coefficient, K i is the differential coefficient, K d is the integration coefficient, τ surge is the vertical input, τ sway is the lateral input, τ yaw Input for the heading; The control rates of the two thrusters on each ship are respectively allocated according to the control rates of the docking ship and the target ship to achieve docking control of the unmanned boat.

2. The unmanned boat docking control method based on an omnidirectional beacon ranging device according to claim 1, characterized in that: The method of calculating the relative tracking error between the docking ship and the target ship in the north-east coordinate system by using the omnidirectional beacon ranging device includes: Assume that the positions of the omnidirectional beacon ranging devices carried on the bow, stern and center of gravity of the target ship are B, C and Q respectively, and the positions of the omnidirectional beacon ranging devices carried on the bow, stern and center of gravity of the docking ship are M, N and P respectively. Draw a perpendicular line to the BC side through M with the foot of the perpendicular being G, draw a perpendicular line to BC through point P and intersect the reverse extension line of the x-axis at point K; The relative tracking error E between the docking ship and the target ship during the long-distance docking process AT_1 for: in, R qp is the distance between the positions Q and P, ∠θ1=∠CPQ+∠KPC, W x and W y They are longitudinal butt joint safety distance and transverse butt joint safety distance respectively; The relative tracking error E between the docking ship and the target ship in the process of close lateral docking AT_2 for: in, The relative tracking error E between the docking ship and the target ship in the close-range longitudinal docking process AT_3 for: in, 3. The unmanned boat docking control method based on an omnidirectional beacon ranging device according to claim 1 or 2, characterized in that: The control rates of the two thrusters on each ship are respectively allocated according to the control rates of the docking ship and the target ship, including: The control rate can be expressed as: t ζ =T ζ (d)T ζ , Where ζ=A,T,T ζ represents the thrust vector controlled by the thruster and has T ζ1 and T ζ2 They represent the thrust of the two propellers on the ship, T ζ (δ) represents the thruster structure matrix and T ζ (δ) = [γ ζ1 ,γ ζ2 ], i=1,2,δ ζi represents the swing angle of the i-th propeller, l xi and l yi represent the longitudinal and transverse positions of the i-th thruster on the ship respectively; The control rates of the two thrusters are allocated according to the control objective function and its constraints.

4. The unmanned boat docking control method based on an omnidirectional beacon ranging device according to claim 3 is characterized in that: The control objective function expression is as follows: Among them, s ζ is the compensation factor, and P and Q are both constant quadratic matrices.

5. The unmanned boat docking control method based on an omnidirectional beacon ranging device according to claim 4, characterized in that: The constraints of the control objective function are: Equality constraints: t ζ =T ζ (d)T ζ +s ζ ; Inequality constraints: in, and T ζi The lower and upper limits of and They are δ ζi The lower and upper limits of and ΔT ζi The lower and upper limits of and are Δδ ζi The lower and upper limits of ΔT ζi and Δδ ζi They respectively represent the rate of change of thrust and swing angle of the i-th propeller of the ship.

6. The unmanned boat docking control method based on an omnidirectional beacon ranging device according to claim 4, characterized in that: The expressions of constant quadratic matrices P and Q are:

7. The unmanned boat docking control method based on an omnidirectional beacon ranging device according to claim 5, characterized in that: The specific values ​​of the inequality constraints are as follows:

8. The unmanned boat docking control method based on an omnidirectional beacon ranging device according to claim 1, characterized in that: The longitudinal input τ surge and the lateral input τ sway 0.8 and 0 respectively.

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