A method and system for compensated towing control of multi-unmanned tugboat formations

Abstract

A multi-unmanned tugboat convoy compensation towing control method includes the following steps: (1) constructing a multi-tugboat towing system; (2) acquiring the reference trajectory, real-time pose, and velocity of the non-driven floating object; (3) determining the time-varying relative offset of each unmanned tugboat relative to the non-driven floating object; (4) controlling each unmanned tugboat to track the corresponding reference desired trajectory based on the reference trajectory and the time-varying relative offset of the non-driven floating object; (5) mapping the horizontal tension of each towing cable to a generalized towing force acting on the non-driven floating object; (7) establishing a force distribution mapping relationship between the horizontal tension of the towing cable and the compensation generalized force; (8) forming a towing cable desired horizontal tension command based on the allocated horizontal tension of the towing cable; (9) inputting the corrected reference desired trajectory or the corrected reference control. This invention can improve the trajectory tracking stability and anti-disturbance capability during multi-unmanned tugboat cooperative towing.

Description

Technical Field

[0001] This invention relates to the field of unmanned vessel cooperative control technology, and in particular to a method and system for compensated towing control of a multi-unmanned tugboat convoy. Background Technology

[0002] In scenarios such as the relocation of large floating hulls in ports, rescue of disabled vessels, dispatch of marine engineering equipment, transfer of floating platform modules, and emergency handling of non-driven floating objects, multiple tugboats are often required to coordinate the towing of non-driven floating objects via towlines. Compared to towing by a single tugboat, coordinated towing by multiple unmanned tugboats can improve maneuvering redundancy and operational flexibility, but it also brings problems such as multi-tugboat coordination, towline force transmission, attitude control of the towed object, and suppression of environmental disturbances.

[0003] One existing approach typically calculates the total control force required for the towed object based on its trajectory error, then distributes this total control force as tension in each tow cable, and subsequently uses the tension and tow cable model to inversely deduce the desired pose of each tugboat. This approach can form a complete closed loop of "total control force - tension - tugboat pose," but its desired tugboat pose is mainly driven by the tension distribution result, resulting in a long control chain. When there are deviations in tension distribution, tow cable model, or sea state disturbances, the target pose of the tugboats may change significantly with the tension solution, thus affecting the geometrically time-varying formation stability of multiple tugboats and the trajectory tracking performance of the towed object.

[0004] Another type of multi-agent formation control method typically sets up a virtual leader or virtual formation center, with multiple tugboats forming a formation around the virtual center. However, when multiple unmanned tugboats are towing undriven floating objects, the actual controlled object is the trajectory and attitude of the undriven floating object, not the trajectory of the virtual center alone. Introducing an intermediate virtual formation center can easily introduce additional conversion errors between the tugboat formation trajectory and the actual motion of the towed object. Summary of the Invention

[0005] The technical problem to be solved by this invention is to address the shortcomings of existing technologies by providing a multi-unmanned tugboat formation towing compensation control method. Based on the reference trajectory of the non-driven floating object and the geometric relationship of the towing cable attachment, a baseline desired trajectory for the unmanned tugboats is directly generated, enabling the unmanned tugboats to first form a geometrically time-varying formation for basic towing. During the unmanned tugboats' tracking of the baseline desired trajectory, the unmanned tugboat thrusters maintain their relative geometric positions. After the towing cable is tightened, horizontal tension is generated. This horizontal tension is transformed into longitudinal force, lateral force, and yaw moment acting on the non-driven floating object through a geometric mapping relationship formed by the direction of action of the towing cable and the lever arm of the towing point. Subsequently, the attitude response of the non-driven floating object is obtained based on the towing system dynamics model, and a robust controller is constructed based on the residual tracking error remaining after basic towing to generate a compensating generalized force. The desired horizontal tension of each towing cable is then obtained through the distribution of the horizontal tension of the towing cable, thereby improving the trajectory tracking stability and anti-disturbance capability during the collaborative towing process of multiple unmanned tugboats.

[0006] Another technical problem to be solved by the present invention is to provide a system for performing the above-described multi-unmanned tugboat formation compensation towing control method.

[0007] The technical problem to be solved by this invention is achieved through the following technical solution. This invention is a method for compensated towing control of a multi-unmanned tugboat convoy, the method comprising the following steps:

[0008] (1) Based on non-driven floating objects, Unmanned tugboat and A multi-tugboat towing system is constructed using towing cables, wherein the non-driven floating object is the towed object. The value is an integer greater than or equal to 3. Each unmanned tugboat is connected to the non-driven floating object via a corresponding towing cable and tows the non-driven floating object in a coordinated manner.

[0009] (2) Obtain the reference trajectory, real-time pose and velocity of the non-driven floating object, the real-time pose and velocity of each unmanned tugboat, the towing point coordinates, towing cable parameters, towing cable action direction and tugboat propulsion capability parameters of each towing cable.

[0010] (3) Based on the reference trajectory of the non-driven floating object and the towing cable attachment geometry between the non-driven floating object, the towing cable and the unmanned tugboat, determine the time-varying relative offset of each unmanned tugboat relative to the non-driven floating object;

[0011] (4) Based on the reference trajectory of the non-driven floating object and the time-varying relative offset, the reference expected trajectory of each unmanned tugboat is directly generated without setting a virtual formation center.

[0012] (5) Based on the reference expected trajectory of each unmanned tugboat, control each unmanned tugboat to track the corresponding reference expected trajectory, so that each unmanned tugboat maintains a geometrically time-varying formation relative to the non-driven floating object in the multi-tugboat towing system, and forms a predetermined towing cable action direction and horizontal distance through the towing cable.

[0013] (6) Based on the nonlinear model of the towing cable and the geometric relationship of the towing cable attachment, the horizontal tension of each towing cable is mapped into the generalized drag force acting on the non-driving floating object, and the pose response and residual tracking error of the non-driving floating object are obtained through the dynamic model of the towing system.

[0014] (7) Based on the residual tracking error, construct a robust controller for stabilizing the residual tracking error, and use the generalized control force output by the robust controller as the compensation generalized force to establish a force distribution mapping relationship between the horizontal tension of the towing cable and the compensation generalized force.

[0015] (8) Based on the upper and lower limits of the horizontal tension of the towing cable, solve the horizontal tension of each towing cable, and form the desired horizontal tension command of the towing cable according to the allocated horizontal tension of the towing cable, or correct the reference desired trajectory or reference control input of each unmanned tugboat.

[0016] (9) Based on the expected horizontal tension command of the towing cable, the corrected reference expected trajectory or the corrected reference control input, control the movement of each unmanned tugboat so as to compensate for the residual tracking error of the non-driven floating object under the towing action of the geometrically time-varying formation.

[0017] The technical problem to be solved by this invention can also be further achieved through the following technical solution: Regarding the multi-unmanned tugboat platoon compensation towing control method described above, the... The desired trajectory of each unmanned tugboat is directly generated based on the reference trajectory of the undriven floating object, the geometry of the tow cable attachment, and the time-varying relative offset of each unmanned tugboat relative to the undriven floating object. The desired position of the unmanned tugboat is:

[0018]

[0019] in, For the first The desired position of the unmanned tugboat. This is the reference pose of the non-driven floating object. For the first The time-varying relative offset of the unmanned tugboat relative to the undriven floating object.

[0020] The technical problem to be solved by the present invention can also be further achieved through the following technical solution: Regarding the multi-unmanned tugboat platooning compensated towing control method described above, in the multi-tugboat towing system, the first... The kinematic and dynamic model of the unmanned tugboat is adopted in the following form:

[0021]

[0022] Among them, subscript , indicating the first An unmanned tugboat, For the first The pose vector of the unmanned tugboat. For velocity vector, This is the coordinate transformation matrix. The inertia matrix, For time-varying environmental disturbances, For the first The control force and torque generated by the propulsion of the unmanned tugboat For the first The root tow cable acts on the first The towing force of an unmanned tugboat;

[0023] The kinematic and dynamic models of non-driven floating objects take the following form:

[0024]

[0025] Among them, subscript Indicates non-driven floating objects. Let be the pose vector of the undriven floating object. For velocity vector, The coordinate transformation matrix is ​​determined by the heading angle of the non-driven floating object. The propulsive force and torque acting directly on the non-driven floating object, The combined towing force of each towing cable acting on the non-driven float; when the non-driven float does not have an actuator, it satisfies .

[0026] The technical problem to be solved by this invention can also be further achieved through the following technical solution: For the multi-unmanned tugboat convoy compensation towing control method described above, based on the towing cable attachment geometry, the horizontal tension of each towing cable is mapped into a combined towing cable force acting on the non-driven floating object, satisfying:

[0027]

[0028] in, Let be the horizontal tension vector of each tow cable. The towing cable force geometry mapping matrix;

[0029] The towing cable force geometry mapping matrix is ​​determined by the direction angle of each towing cable and the coordinates of the towing point of each towing cable on the non-driven floating object. When the multi-tugboat towing system includes 4 unmanned tugboats and 4 towing cables, the towing cable force geometry mapping matrix is:

[0030]

[0031] in, For the first The direction angle of the tow cable's action. For the first The coordinates of the towing point of the root towing cable on the non-driven floating object.

[0032] The technical problem to be solved by this invention can also be further achieved through the following technical solution: For the multi-unmanned tugboat formation compensation towing control method described above, the horizontal tension of each towing cable is obtained by solving a nonlinear catenary model determined by the horizontal distance between the two ends of the towing cable and the towing cable parameters, satisfying:

[0033]

[0034] in, For the first The horizontal tension of the towing cable, The horizontal distance between the two ends of the tow cable. This refers to the length of the tow cable. Weight per unit length of tow cable. For Young's modulus, This represents the cross-sectional area of ​​the tow cable.

[0035] The technical problem to be solved by this invention can also be further achieved through the following technical solution: For the multi-unmanned tugboat platooning compensated towing control method described above, the residual tracking error includes the pose error and velocity error of the non-driven floating object, satisfying:

[0036]

[0037] in, For pose error, For speed error, This is the reference pose of the non-driven floating object. This is the filtered virtual control quantity;

[0038] A robust controller for stabilizing the residual tracking error is constructed based on the residual tracking error, and the output of the robust controller is used as the compensation generalized force, satisfying:

[0039]

[0040] in, For virtual control laws, This is the filtered virtual control quantity. The compensated generalized force output by the robust controller. and It is a positive definite gain matrix.

[0041] The technical problem to be solved by this invention can also be further achieved through the following technical solution: For the multi-unmanned tugboat platoon compensated towing control method described above, based on the compensated generalized force output by the robust controller, a force distribution optimization model between the horizontal tension of the towing cable and the compensated generalized force is established, satisfying:

[0042]

[0043] in, For the first The horizontal tension of the towing cable, This is the weight matrix. The towing cable force geometry mapping matrix, For the first The preset minimum horizontal tension of the towing cable, For the first The maximum horizontal tension that the towing cable can provide.

[0044] The technical problem to be solved by this invention can also be further achieved through the following technical solution: For the multi-unmanned tugboat convoy compensation towing control method described above, the allocated horizontal tension of the towing cables is used to form the desired horizontal tension command for each towing cable, or to determine the horizontal tension relative to the first towing cable based on a nonlinear catenary model. The horizontal distance between the two ends of the towing cable corresponding to the horizontal tension of the towing cable, combined with the first The coordinates of the towing point of the towing cable on the non-driven floating object and the direction of the towing cable's action are used to determine the first... The corrected desired position of the unmanned tugboat; or the corrected baseline control input generated based on the direction of the tow cable, the allocated horizontal tension, and the configuration of the unmanned tugboat's thrusters.

[0045] The technical problem to be solved by the present invention can also be further achieved through the following technical solution: For the multi-unmanned tugboat platoon compensating towing control method described above, a multi-unmanned tugboat platoon compensating towing control system is provided, comprising:

[0046] The status acquisition module is used to acquire status information of non-driven floating objects, unmanned tugboats, and tow cables;

[0047] The geometric time-varying formation generation module is used to generate the baseline expected trajectory of each unmanned tug based on the reference trajectory of the non-driven floating object and the tow cable attachment geometry between the non-driven floating object, the tow cable, and the unmanned tug.

[0048] The basic formation control module is used to control each unmanned tugboat to track the baseline desired trajectory and form a geometrically time-varying formation basic towing through tow cables;

[0049] The towing system feedback module is used to obtain the pose response and residual tracking error of the non-driven floating object based on the towing cable nonlinear model and the towing system dynamic model.

[0050] The compensation generalized force generation module is used to generate a compensation generalized force based on the residual tracking error;

[0051] The tow cable horizontal tension distribution module is used to distribute the compensation generalized force into the horizontal tension of each tow cable;

[0052] The correction control module is used to generate the desired horizontal tension command for the tow cable based on the allocated horizontal tension of the tow cable, or to correct the reference desired trajectory or reference control input of each unmanned tugboat.

[0053] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0054] First, the present invention uses the reference trajectory of the non-driven floating object, the geometric relationship of the towing cable attachment, and the time-varying relative offset of the unmanned tugboat as the basis for generating the reference expected trajectory of the unmanned tugboat, which can directly form a geometrically time-varying formation towing process of multiple unmanned tugboats.

[0055] Second, the present invention clarifies the interaction relationship between the unmanned tugboat propeller, the horizontal tension of the towing cable and the geometric mapping of the towing cable force. The unmanned tugboat propeller maintains a relative geometric position, and the towing cable generates horizontal tension after being tightened. The direction of action of the towing cable and the lever arm of the towing point convert the horizontal tension into a generalized towing force acting on the non-driving floating object.

[0056] Third, the present invention constructs a robust controller based on the residual tracking error after the geometric time-varying formation towing, and achieves residual tracking error compensation through the horizontal tension distribution of the towing cable, so that the basic towing control and error compensation control are implemented in layers, which is beneficial to improving the control stability during the collaborative towing process of multiple unmanned tugboats.

[0057] Fourth, by constraining the upper and lower limits of the horizontal tension of the tow cable, this invention ensures that the allocated horizontal tension of the tow cable meets the requirements of the tow cable's load-bearing capacity, which is beneficial to improving the trajectory tracking accuracy and anti-interference capability under complex sea conditions. Attached Figure Description

[0058] Figure 1 This is a flowchart of one method of the present invention;

[0059] Figure 2This is a schematic diagram illustrating the generation of the unmanned tugboat's baseline desired trajectory based on the geometric relationship between the non-driven floating object, tow cable, and unmanned tugboat under conditions without a virtual formation center, according to the present invention.

[0060] Figure 3 This is a schematic diagram illustrating the relationship between residual tracking error force distribution compensation, tow cable horizontal tension distribution, and trajectory / input correction in this invention. Detailed Implementation

[0061] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0062] refer to Figure 1-3 A method for compensated towing control of multi-unmanned tugboat formations, applicable to non-driven floating objects, Unmanned tugboat and A cooperative towing system using root towing cables, the method comprising the following steps:

[0063] (1) Obtain the reference trajectory of the non-driven floating object, the actual position and velocity of the non-driven floating object, the actual position and velocity of the unmanned tugboat, the coordinates of the towing point, the direction of the towing cable, the parameters of the towing cable, and the propulsion capability parameters of the tugboat.

[0064] (2) Without setting a virtual formation center, the time-varying relative offset of each unmanned tugboat relative to the non-driven floating object is determined directly based on the reference trajectory of the non-driven floating object and the tow cable attachment geometry between the non-driven floating object, the tow cable, and the unmanned tugboat, and the reference expected trajectory of each unmanned tugboat is generated:

[0065]

[0066] in, For the first The baseline desired pose of the unmanned tugboat. For reference trajectory of non-driven floating objects, The first, determined by the tow cable configuration and tow cable attachment geometry The time-varying relative offset of an unmanned tugboat relative to a non-driven floating object.

[0067] (3) Each unmanned tugboat tracks the baseline desired trajectory, maintaining a predetermined geometrically time-varying formation relative to the undriven floating object. The unmanned tugboat thrusters are used to maintain this relative position, and the tow cable is taut at a corresponding horizontal distance, generating horizontal tension. The direction of the tow cable and the lever arm at the towing point jointly determine the force and torque generated by this tension on the undriven floating object. The horizontal tension of the tow cable can be determined by a nonlinear catenary model:

[0068]

[0069] in, For the first The horizontal tension of the towing cable, The horizontal distance between the two ends of the tow cable. This refers to the length of the tow cable. Weight per unit length of tow cable. For Young's modulus, This represents the cross-sectional area of ​​the tow cable.

[0070] (4) Based on the horizontal tension of the towing cables and the geometric relationship of the towing cable attachment, the horizontal tension of each towing cable is mapped into a generalized drag force acting on the non-driven floating object, and this generalized drag force is input into the dynamic model of the towing system to obtain the pose response of the non-driven floating object:

[0071]

[0072] in, Let be the horizontal tension vector of each tow cable. This is the geometric mapping matrix of the towing cable force.

[0073] When the multi-tugboat towing system includes 4 unmanned tugboats and 4 towlines, the towline force geometry mapping matrix is:

[0074]

[0075] in, Indicates the first The direction angle of the towing cable's action; Indicates the first The coordinates of the towing point of the towing cable on the non-driven floating object. Thus, the geometric relationship between the tugboat and the non-driven floating object does not directly generate force, but rather determines how the tension of the towing cable is converted into a generalized towing force on the non-driven floating object by changing the direction of the towing cable, the horizontal distance, and the lever arm.

[0076] (5) Feedback on the pose response of the undriven floating object based on the dynamic model of the undriven floating object, and calculate the residual tracking error that still exists after the basic geometric time-varying formation towing. The dynamic model of the undriven floating object can be expressed as:

[0077]

[0078] Among them, subscript Indicates non-driven floating objects. Let be the pose vector of the undriven floating object. For velocity vector, The coordinate transformation matrix is ​​determined by the heading angle of the non-driven floating object. The propulsive force and torque acting directly on the non-driven floating object, The combined towing force of each towing cable acting on the non-driven float; when the non-driven float does not have an actuator, it satisfies Therefore, the motion of the floating object is mainly caused by the resultant force of the towing cables. drive.

[0079] (6) Generate a compensation generalized force based on the residual tracking error. The residual tracking error is expressed as:

[0080]

[0081] in, For pose error, For speed error, This is the reference pose of the non-driven floating object. This is the filtered virtual control quantity.

[0082] A robust controller for stabilizing the residual tracking error is constructed based on the residual tracking error, and its control law is expressed as follows:

[0083]

[0084] in, For virtual control laws, This is the filtered virtual control quantity. The compensated generalized force output by the robust controller. and It is a positive definite gain matrix.

[0085] In this invention, the generalized control force output by the robust controller is... It serves as a compensating generalized force to compensate for residual tracking errors and is used for subsequent horizontal tension distribution of the tow cable.

[0086] (7) Establish the force distribution mapping relationship between the horizontal tension of the towing cable and the compensating generalized force, and solve for the horizontal tension of each towing cable. The compensating generalized force is based on the output of the robust controller. Establish a force distribution mapping relationship between the horizontal tension of the towing cable and the compensated generalized force, satisfying:

[0087]

[0088] In one implementation, the horizontal tension of each tow cable is obtained through the following optimization model:

[0089]

[0090] in, Here is the weight matrix. The constraints of the optimization model include upper and lower limits of the horizontal tension of the towing cable, satisfying:

[0091]

[0092] in, , For the first The horizontal tension of the towing cable, For the first The preset minimum horizontal tension of the towing cable, For the first The maximum horizontal tension that the tow cable can provide,

[0093] (8) Generate the desired horizontal tension command for the towline based on the allocated horizontal tension of the towline, or correct the reference desired trajectory or reference control input of each unmanned tugboat. If the trajectory correction method is adopted, the first towline will be adjusted according to the nonlinear towline model. The horizontal tension obtained from the distribution of the root tow cable Converted to the corresponding horizontal distance between the two ends of the tow cable , and combined with the first The coordinates of the towing point of the towing cable on the non-driven floating object and the direction of the towing cable's action are used to determine the first... The corrected expected position of the unmanned tugboat.

[0094]

[0095] in, For the first The horizontal distance between the two ends of the tow cable For the first The horizontal tension distributed by the tow cable This represents the horizontal tension-horizontal distance inverse mapping determined by the nonlinear catenary model. This is a reference position for non-driven floating objects. For the first The corrected expected position of the unmanned tugboat. For the first The tow cable's direction of action is a unit vector. If a control input correction method is used, a corresponding control input correction amount is generated based on the tow cable's direction of action, the allocated horizontal tension, and the unmanned tugboat's propulsion configuration, and then superimposed on the baseline control input.

[0096] (9) Each unmanned tugboat executes the modified control command or the desired horizontal tension command of the towing cable, so that the allocated horizontal tension of the towing cable acts on the non-driven floating object through the towing cable, thereby further reducing the trajectory error of the non-driven floating object on the basis of geometric time-varying formation towing.

[0097] Example 1, such as Figure 1 As shown, the cooperative towing system in this embodiment includes a non-driven floating object, four unmanned tugboats, and four towing cables. The non-driven floating object can be a large, unpowered floating body, a marine engineering module, a disused vessel, or a large floating object in a port. Each unmanned tugboat is connected to a corresponding towing point on the non-driven floating object via a towing cable.

[0098] During the control cycle The status acquisition module obtains the reference trajectory of the non-driven floating object. Actual position Actual speed Actual position of each unmanned tugboat ,speed Drag point coordinates Direction of action of the towing cable Horizontal distance of tow cable The parameters of the tow cable and the upper and lower limits of the propulsion capacity.

[0099] The geometrically time-varying formation generation module uses the reference trajectory of the non-driven floating object and the geometry of the tow cable attachment as the direct benchmark for generating the trajectories of each unmanned tugboat. For the first... A number of unmanned tugboats, according to Calculate its baseline expected trajectory. Here It is determined by the configuration of the towing cable, the location of the towing point, the direction of the towing cable, and the horizontal distance of the towing cable.

[0100] The basic formation control module generates baseline control inputs based on the baseline desired trajectory, enabling each unmanned tugboat to track its own baseline desired trajectory. While the tugboats are tracking the baseline desired trajectory, the thrusters are used to maintain the tugboat's geometric position relative to the undriven floating object; at this geometric position, a corresponding horizontal distance is formed between the two ends of the towline, and the towline generates horizontal tension through a nonlinear towline model. .

[0101] The drag system feedback module is based on The horizontal tension of the towline is mapped into a composite towline force acting on the non-driven floating object. This force, after being incorporated into the dynamics model of the non-driven floating object, yields the attitude response of the non-driven floating object. Therefore, the dragging effect generated by the geometric relationship in this invention is specifically manifested as follows: the towline attachment geometry between the non-driven floating object, the towline, and the unmanned tugboat determines the direction of the towline action, the horizontal distance of the towline, and the lever arm of the towing point; the unmanned tugboat maintains the aforementioned geometric relationship through its thrusters while tracking the reference desired trajectory, causing the towline to generate horizontal tension; this horizontal tension is then transformed into a generalized dragging force acting on the non-driven floating object through towline force geometric mapping.

[0102] Due to the influence of factors such as sea wind, waves, currents, unmodeled dynamics of the towline, and hydrodynamic uncertainties of non-driven floating objects, residual trajectory errors may still exist in non-driven floating objects after the basic geometrically time-varying formation towing. The residual tracking error calculation module calculates the residual tracking error based on the actual pose of the non-driven floating objects and the reference trajectory. and The compensating generalized force generation module generates the compensating generalized force accordingly. .

[0103] The tow cable horizontal tension distribution module uses the compensated generalized force output by the robust controller. Solve for the horizontal tension of each towing cable Specifically, the towing cable geometric mapping matrix is ​​formed by utilizing the towing cable's direction of action and the lever arm at the towing point. ,Establish The force distribution relationship is determined, and the horizontal tension of each tow cable is solved under the constraints of the upper and lower limits of the tow cable tension.

[0104] The correction control module can use the allocated towline horizontal tension as the desired horizontal tension command for the towline, or correct the baseline desired trajectory or baseline control input of each unmanned tugboat based on the allocated towline horizontal tension. If the trajectory correction method is used, it will be based on the nonlinear towline model... Converted to the corresponding horizontal distance between the two ends of the tow cable The desired position after correction is determined along the direction of the tow cable. If the control input correction method is used, the control input correction amount is generated according to the direction of the tow cable, the distributed horizontal tension and the configuration of the tugboat propeller, and then superimposed on the reference control input.

[0105] When the residual tracking error is small, a compensation trigger threshold can be set to avoid frequent application of compensation tension. .when When, maintain the current horizontal tension command of the tow cable or adjust smoothly according to the preset attenuation coefficient; when At that time, the residual tracking error force distribution compensation is initiated, and the horizontal tension of each tow cable is recalculated.

[0106] As can be seen from the above embodiments, the core of the present invention lies in:

[0107] First, a geometrically time-varying formation trajectory for unmanned tugboats is directly generated using the reference trajectory of the non-driven floating object and the geometry of the tow cable attachment. Then, the unmanned tugboats track this trajectory, causing the tow cable to generate horizontal tension, which is then applied to the non-driven floating object via tow cable force geometry mapping. Finally, the horizontal tension of the tow cable is allocated based on the residual tracking error of the non-driven floating object, generating a desired horizontal tension command for the tow cable, a baseline desired trajectory correction, or a control input correction. This invention uses the reference trajectory of the non-driven floating object and the geometry of the tow cable attachment as the basis for generating the baseline desired trajectory of the unmanned tugboat. Combined with the horizontal tension allocation of the tow cable corresponding to the residual tracking error, it achieves layered control of geometrically time-varying formation towing and residual tracking error compensation, which is beneficial for improving trajectory tracking stability and anti-disturbance capability during multi-unmanned tugboat cooperative towing.

Claims

1. A method for multi-unmanned tugboat formation compensation towing control, characterized in that: The method includes the following steps: (1) based on a non-driven floating object, an unmanned tugboat, and a plurality of unmanned tugboats are connected to the non-driven floating object through a corresponding tow cable, and cooperatively tow the non-driven floating object, an integer greater than or equal to 3, and each unmanned tugboat is connected to the non-driven floating object through a corresponding tow cable and cooperatively tows the non-driven floating object. (2) Obtain the reference trajectory, real-time pose and velocity of the non-driven floating object, the real-time pose and velocity of each unmanned tugboat, the towing point coordinates, towing cable parameters, towing cable action direction and tugboat propulsion capability parameters of each towing cable. (3) Based on the reference trajectory of the non-driven floating object and the towing cable attachment geometry between the non-driven floating object, the towing cable and the unmanned tugboat, determine the time-varying relative offset of each unmanned tugboat relative to the non-driven floating object; (4) Based on the reference trajectory of the non-driven floating object and the time-varying relative offset, the reference expected trajectory of each unmanned tugboat is directly generated without setting a virtual formation center. (5) Based on the reference expected trajectory of each unmanned tugboat, control each unmanned tugboat to track the corresponding reference expected trajectory, so that each unmanned tugboat maintains a geometrically time-varying formation relative to the non-driven floating object in the multi-tugboat towing system, and forms a predetermined towing cable action direction and horizontal distance through the towing cable. (6) Based on the nonlinear model of the towing cable and the geometric relationship of the towing cable attachment, the horizontal tension of each towing cable is mapped into the generalized drag force acting on the non-driving floating object, and the pose response and residual tracking error of the non-driving floating object are obtained through the dynamic model of the towing system. (7) Based on the residual tracking error, construct a robust controller for stabilizing the residual tracking error, and use the generalized control force output by the robust controller as the compensation generalized force to establish a force distribution mapping relationship between the horizontal tension of the towing cable and the compensation generalized force. (8) Based on the upper and lower limits of the horizontal tension of the towing cable, solve the horizontal tension of each towing cable, and form the desired horizontal tension command of the towing cable according to the allocated horizontal tension of the towing cable, or correct the reference desired trajectory or reference control input of each unmanned tugboat. (9) Based on the expected horizontal tension command of the towing cable, the corrected reference expected trajectory or the corrected reference control input, control the movement of each unmanned tugboat to compensate for the residual tracking error of the non-driven floating object under the towing action of the geometrically time-varying formation.

2. The multi-unmanned tugboat platooning compensation towing control method according to claim 1, characterized in that: The The desired trajectory of each unmanned tugboat is generated directly based on the reference trajectory of the non-driven floater, the towline attachment geometry, and the time-varying relative offset of each unmanned tugboat with respect to the non-driven floater, the first The desired pose of each unmanned tugboat is: wherein, is the desired pose of the unmanned tugboat, is the reference pose of the non-driven float, is the desired pose of the unmanned tugboat relative to the non-driven float.

3. The multi-unmanned tugboat platooning compensation towing control method according to claim 1, characterized in that: In the multi-tugboat towing system, the first The kinematic and dynamic model of the unmanned tugboat is adopted in the following form: Among them, subscript , indicating the first An unmanned tugboat, For the first The pose vector of an unmanned tugboat. For velocity vector, This is the coordinate transformation matrix. The inertia matrix, For time-varying environmental disturbances, For the first The control force and torque generated by the propulsion of the unmanned tugboat For the first The root tow cable acts on the first The towing force of an unmanned tugboat; The kinematic and dynamic models of non-driven floating objects take the following form: Among them, subscript Indicates non-driven floating objects. Let be the pose vector of the undriven floating object. For velocity vector, The coordinate transformation matrix is ​​determined by the heading angle of the non-driven floating object. The propulsive force and torque acting directly on the non-driven floating object, The combined towing force of each towing cable acting on the non-driven float; when the non-driven float does not have an actuator, it satisfies .

4. The multi-unmanned tugboat platooning compensation towing control method according to claim 3, characterized in that: Based on the tow cable attachment geometry, the horizontal tension of each tow cable is mapped to the combined tow cable force acting on the non-driven floating object, satisfying: in, Let be the horizontal tension vector of each tow cable. The towing cable force geometry mapping matrix; The towing cable force geometry mapping matrix is ​​determined by the direction angle of each towing cable and the coordinates of the towing point of each towing cable on the non-driven floating object. When the multi-tugboat towing system includes 4 unmanned tugboats and 4 towing cables, the towing cable force geometry mapping matrix is: in, For the first The direction angle of the tow cable's action. For the first The coordinates of the towing point of the root towing cable on the non-driven floating object.

5. The multi-unmanned tugboat platooning compensation towing control method according to claim 1, characterized in that: The horizontal tension of each towing cable is obtained by solving a nonlinear catenary model determined by the horizontal distance between the two ends of the towing cable and the towing cable parameters, satisfying the following: in, For the first The horizontal tension of the towing cable, The horizontal distance between the two ends of the tow cable. This refers to the length of the tow cable. Weight per unit length of tow cable. For Young's modulus, This represents the cross-sectional area of ​​the tow cable.

6. The multi-unmanned tugboat platooning compensation towing control method according to claim 1, characterized in that: The residual tracking error includes the pose error and velocity error of the undriven floating object, satisfying: in, For pose error, For speed error, This is the reference pose of the non-driven floating object. This is the filtered virtual control quantity; A robust controller for stabilizing the residual tracking error is constructed based on the residual tracking error, and the output of the robust controller is used as the compensation generalized force, satisfying: in, For virtual control laws, This is the filtered virtual control quantity. The compensated generalized force output by the robust controller. and It is a positive definite gain matrix.

7. The multi-unmanned tugboat platooning compensation towing control method according to claim 6, characterized in that: Based on the compensated generalized force output by the robust controller, a force distribution optimization model is established between the horizontal tension of the towing cable and the compensated generalized force, satisfying: in, For the first The horizontal tension of the towing cable, This is the weight matrix. The towing cable force geometry mapping matrix, For the first The preset minimum horizontal tension of the towing cable, For the first The maximum horizontal tension that the tow cable can provide.

8. The multi-unmanned tugboat platooning compensation towing control method according to claim 1, characterized in that: The allocated horizontal tension of the tow cable is used to form the desired horizontal tension command for each tow cable, or to determine the horizontal tension relative to the first tow cable based on a nonlinear catenary model. The horizontal distance between the two ends of the towing cable corresponding to the horizontal tension of the towing cable, combined with the first The coordinates of the towing point of the towing cable on the non-driven floating object and the direction of the towing cable's action are used to determine the first... The corrected expected position of the unmanned tugboat; Alternatively, a modified baseline control input can be generated based on the direction of the towing cable, the allocated horizontal tension, and the configuration of the unmanned tugboat's thrusters.

9. A multi-unmanned tugboat platooning compensation towing control system, characterized in that: The system is used to execute the multi-unmanned tugboat platooning compensated towing control method according to any one of claims 1-8, the system comprising: The status acquisition module is used to acquire status information of non-driven floating objects, unmanned tugboats, and tow cables; The geometric time-varying formation generation module is used to generate the baseline expected trajectory of each unmanned tug based on the reference trajectory of the non-driven floating object and the tow cable attachment geometry between the non-driven floating object, the tow cable, and the unmanned tug. The basic formation control module is used to control each unmanned tugboat to track the baseline desired trajectory and form a geometrically time-varying formation basic towing through tow cables; The towing system feedback module is used to obtain the pose response and residual tracking error of the non-driven floating object based on the towing cable nonlinear model and the towing system dynamic model. The compensation generalized force generation module is used to generate a compensation generalized force based on the residual tracking error; The tow cable horizontal tension distribution module is used to distribute the compensation generalized force into the horizontal tension of each tow cable; The correction control module is used to generate the desired horizontal tension command for the tow cable based on the allocated horizontal tension of the tow cable, or to correct the reference desired trajectory or reference control input of each unmanned tugboat.

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