Unmanned ship-aircraft platform cooperative system landing process control method and device

Abstract

The invention provides an unmanned ship-aircraft platform cooperative system landing process control method and device, and relates to the technical field of control systems.The method comprises the steps that in the landing process of a target unmanned aerial vehicle, based on an unmanned ship attitude controller, a target unmanned ship is controlled to keep the attitude; based on an unmanned aerial vehicle vertical controller and an unmanned aerial vehicle contact controller, the descending and soft landing process of the target unmanned aerial vehicle on the target unmanned ship is controlled; the unmanned ship attitude controller and the unmanned aerial vehicle vertical controller are obtained by training an extended state observer; the unmanned aerial vehicle contact controller is obtained based on an admittance control equation. The method can ensure that the unmanned aerial vehicle carries out a high-robustness soft landing process on the sea surface unmanned ship, thereby effectively improving the intelligent level of an unmanned ship-aircraft platform and the autonomous exploration capability of offshore equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of control systems, and particularly to a control method and device for the landing process of an unmanned surface vehicle (USV)-unmanned aerial vehicle (UAV) platform collaborative system. Background Art

[0002] An unmanned surface vehicle (USV) can replace or cooperate with humans in complex repetitive ocean tasks, such as environmental and climate monitoring, hydrographic surveys, sea surface monitoring, search and rescue, and naval operations. In these tasks, the USV needs to have a comprehensive perception of the area around itself. However, sensors such as cameras and radars installed on the USV have a low detection angle of view, so that they only have a limited detection range. Therefore, they cannot effectively detect task targets such as floating objects and fallen personnel around, which seriously affects the safety and efficiency of the USV. To solve this problem, researchers use an unmanned aerial vehicle (UAV) to provide a wider aerial view and more accurate environmental perception capabilities. Based on this advantage, the cooperative USV-UAV platform collaborative system has attracted considerable attention in the fields of robotics, automation, ocean engineering, etc.

[0003] In recent years, rapid progress has been made in robotics and automation technologies, and various USV-UAV platform collaborative systems suitable for different applications have been developed. In the USV-UAV platform collaborative system, the landing of the UAV on the USV is one of the most critical technologies. The USV-UAV platform collaborative control system usually adopts a cascaded structure composed of a high-level navigation strategy and a low-level motion controller. The high-level strategy generates a path according to the task target and the surrounding situation, and then inputs the path as a reference signal into the motion controller.

[0004] There are already various control implementation methods for the USV motion controller, from classical PID control to many advanced control algorithms, such as sliding mode control, adaptive and backstepping control, model predictive control, etc. To handle external disturbances from waves and wind, neural network-based adaptive methods and disturbance observers have also been introduced into the relevant controller design. However, due to the very complex physical mechanism of hydrodynamics, the dynamics of the USV are highly nonlinear. It is quite difficult to determine the model structure and parameters of the USV. Therefore, due to model errors and uncertainties, many of the above model-based control methods cannot obtain ideal control performance. Due to the low positioning accuracy and the limitations of traditional controllers, unexpected oscillations occur in the approaching trajectory of the USV.

[0005] During the flight of the UAV, especially during the landing phase, trajectory planning and motion control are crucial. For a long time, it has been a challenge to model the complex interactions between the UAV and the USV using traditional aerodynamic laws. During the hovering and landing phases, the motion state of the USV may change rapidly and unstably, resulting in inaccurate measurements and making it difficult to achieve precise control. Similarly, existing models and control methods have limited accuracy, require complex calculations, or need manual assistance to achieve stable hovering or landing. Summary of the Invention

[0006] The present invention provides a control method and device for the landing process of an unmanned boat-aircraft platform collaborative system, to solve the defects in the existing technology that the models and control methods have limited accuracy, require complex calculations, or need manual assistance to achieve stable hovering or landing, and to realize a highly robust soft landing process of the UAV on the USV on the sea surface, thereby improving the intelligent level of the unmanned boat-aircraft platform and the autonomous exploration ability of marine equipment.

[0007] The present invention provides a control method for the landing process of an unmanned boat-aircraft platform collaborative system, including the following steps: During the landing process of the target UAV, based on the unmanned boat attitude controller, control the target unmanned boat to maintain its attitude; Based on the UAV vertical controller and the UAV contact controller, control the descent and soft landing process of the target UAV on the target unmanned boat; The unmanned boat attitude controller and the UAV vertical controller are obtained by training an extended state observer; the UAV contact controller is obtained based on the admittance control equation.

[0008] According to a control method for the landing process of an unmanned boat-aircraft platform collaborative system provided by the present invention, the obtaining method of the unmanned boat attitude controller includes: Based on the motion equation of the unmanned boat, design a first extended state observer; Based on the first extended state observer, determine the linear feedback control law; Take the composite sine function as the disturbance observation input, and take the integral of the absolute value of the error and the difference between the coefficients of the first 5th-order Fourier series as the optimization objective function, and determine the parameters of the first extended state observer through an optimization algorithm to obtain the trained unmanned boat attitude controller.

[0009] According to a control method for the landing process of an unmanned boat-aircraft platform collaborative system provided by the present invention, the obtaining method of the UAV vertical controller includes: Based on the system dynamics equation of the UAV in the vertical direction, design a second extended state observer; Based on the second extended state observer, determine the linear feedback control law; Take the integral of the absolute value of the error as the optimization objective function, and determine the parameters of the second extended state observer through an optimization algorithm to obtain a trained vertical controller for the unmanned aerial vehicle.

[0010] According to a control method for the landing process of an unmanned boat-aircraft platform collaborative system provided by the present invention, the acquisition method of the unmanned aerial vehicle contact controller includes: Based on the desired mass matrix, desired damping matrix, and desired stiffness matrix, determine the admittance control equation of the unmanned aerial vehicle; Based on the desired contact force only in the vertical direction, adjust the parameters of the desired mass matrix, the desired damping matrix, and the desired stiffness matrix in the admittance control equation to obtain the unmanned aerial vehicle contact controller.

[0011] According to a control method for the landing process of an unmanned boat-aircraft platform collaborative system provided by the present invention, the initial parameters of the first extended state observer are determined based on the bandwidth of the first extended state observer; and / or, the initial parameters of the second extended state observer are determined based on the bandwidth of the second extended state observer.

[0012] According to a control method for the landing process of an unmanned boat-aircraft platform collaborative system provided by the present invention, the optimization algorithm is a genetic algorithm.

[0013] The present invention also provides a control device for the landing process of an unmanned boat-aircraft platform collaborative system, including the following modules: An unmanned boat control module, configured to control the target unmanned boat to maintain its attitude based on the unmanned boat attitude controller during the landing process of the target unmanned aerial vehicle; An unmanned aerial vehicle control module, configured to control the descent and soft landing process of the target unmanned aerial vehicle on the target unmanned boat based on the vertical controller of the unmanned aerial vehicle and the contact controller of the unmanned aerial vehicle; The unmanned boat attitude controller and the vertical controller of the unmanned aerial vehicle are obtained by training an extended state observer; the contact controller of the unmanned aerial vehicle is obtained based on the admittance control equation.

[0014] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the control method for the landing process of an unmanned boat-aircraft platform collaborative system as described in any one of the above is implemented.

[0015] The present invention also provides a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the control method for the landing process of an unmanned boat-aircraft platform collaborative system as described in any one of the above is implemented.

[0016] The present invention also provides a computer program product, including a computer program which, when executed by a processor, implements the control method for the landing process of the unmanned boat-aircraft platform cooperation system as described in any one of the above.

[0017] The control method and device for the landing process of the unmanned boat-aircraft platform cooperation system provided by the present invention obtain an unmanned boat attitude controller and an unmanned aerial vehicle vertical controller through training an extended state observer, and obtain an unmanned aerial vehicle contact controller based on the admittance control equation. During the landing process of the target unmanned aerial vehicle, the target unmanned boat can be controlled to maintain its attitude by the unmanned boat attitude controller, which can reduce the difficulty of the target unmanned aerial vehicle landing. Then, through the unmanned aerial vehicle vertical controller and the unmanned aerial vehicle contact controller, the descent and soft landing process of the target unmanned aerial vehicle on the target unmanned boat can be controlled, which can ensure a highly robust soft landing process of the unmanned aerial vehicle on the sea unmanned boat, thereby effectively improving the intelligent level of the unmanned boat-aircraft platform and the autonomous exploration ability of marine equipment. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0019] Figure 1 It is a schematic flowchart of the control method for the landing process of the unmanned boat-aircraft platform cooperation system provided by the present invention.

[0020] Figure 2 It is a schematic overall flowchart of the cooperative landing control design of the unmanned boat-aircraft platform provided by the present invention.

[0021] Figure 3 It is a schematic complete control flowchart of the unmanned boat-aircraft platform cooperation provided by the present invention.

[0022] Figure 4 It is a schematic structural diagram of the control device for the landing process of the unmanned boat-aircraft platform cooperation system provided by the present invention.

[0023] Figure 5 It is a schematic structural diagram of the electronic device provided by the present invention. Detailed Embodiments

[0024] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the present invention. Apparently, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts belong to the scope of protection of the present invention.

[0025] Figure 1 is a schematic flowchart of the control method for the landing process of the unmanned boat-aircraft platform collaborative system provided by the present invention. As Figure 1 shown, the method includes the following steps: Step 100: During the landing process of the target unmanned aerial vehicle (UAV), based on the unmanned boat attitude controller, control the target unmanned boat to maintain its attitude.

[0026] Step 101: Based on the UAV vertical controller and the UAV contact controller, control the descent and soft landing process of the target UAV on the target unmanned boat.

[0027] Among them, the unmanned boat attitude controller and the UAV vertical controller are obtained by training an extended state observer; the UAV contact controller is obtained based on the admittance control equation.

[0028] Specifically, the target UAV is the UAV that needs to land on the target unmanned boat. In the embodiments of the present invention, the target UAV and the target unmanned boat are collaboratively controlled to complete the landing process of the target UAV on the target unmanned boat.

[0029] First, in the embodiments of the present invention, the unmanned boat needs to maintain a horizontal attitude during navigation, which requires controlling its attitudes in three directions (yaw angle, pitch angle, and roll angle). To achieve this goal, an extended state observer (ESO) can be used to compensate for the nonlinear, time-varying characteristics, and disturbances of the system.

[0030] Therefore, an extended state observer can be trained for the motion equation of the unmanned boat on the sea surface to obtain the unmanned boat attitude controller. The extended state observer can estimate the disturbances in the system in real time and compensate for them, improving the robustness and performance of the system, so as to ensure that the unmanned boat can also maintain its own horizontal attitude during navigation in the presence of disturbances.

[0031] Generally, during the landing process of the UAV on the unmanned boat on the sea surface, its ideal flight attitude should be horizontal, that is, the roll angle and pitch angle should be close to 0. This attitude control process can be realized by the typical proportional-derivative (PD) controller of the UAV itself.

[0032] Therefore, the main movement of the drone is in the vertical z-direction. A vertical controller for the drone can be designed. The design of the vertical controller of the drone is similar to that of the attitude controller of the unmanned boat. For the system dynamics equation of the drone in the vertical direction, an extended state observer can be trained to obtain the vertical controller of the drone. The extended state observer can estimate the disturbances in the system in real time and compensate for them, improving the robustness and performance of the system, so as to ensure that the drone can also remain unaffected by disturbances during the descent process even when there are disturbances in the system.

[0033] However, affected by factors such as sea waves, there will still be certain control errors in the attitude of the unmanned boat. Therefore, a compliant controller in the attitude direction of the drone needs to be designed to reduce the contact force and achieve the soft landing process of the drone.

[0034] During the contact process between the drone and the unmanned boat, the contact controller of the drone can be obtained according to the admittance control equation. By controlling the difference between the desired contact force and the actual contact force, the state of the drone is adjusted, so as to ensure the stability of the drone during the landing process.

[0035] The control method for the landing process of the unmanned boat-drone platform collaborative system provided by the present invention obtains the attitude controller of the unmanned boat and the vertical controller of the drone through training the extended state observer, and obtains the contact controller of the drone based on the admittance control equation. During the landing process of the target drone, the attitude of the target unmanned boat can be controlled by the attitude controller of the unmanned boat, which can reduce the difficulty of the target drone's landing. Then, through the vertical controller and the contact controller of the drone, the descent and soft landing process of the target drone on the target unmanned boat can be controlled, which can ensure a highly robust soft landing process of the drone on the sea unmanned boat, thereby effectively improving the intelligent level of the unmanned boat-drone platform and the autonomous exploration ability of marine equipment.

[0036] According to a control method for the landing process of an unmanned boat-drone platform collaborative system provided by the present invention, the acquisition method of the attitude controller of the unmanned boat includes: Design a first extended state observer based on the motion equation of the unmanned boat; Determine the linear feedback control law based on the first extended state observer; Take the composite sine function as the disturbance observation input, and take the integral of the absolute value of the error and the difference between the coefficients of the first 5-order Fourier series as the optimization objective function. Determine the parameters of the first extended state observer through an optimization algorithm to obtain the trained attitude controller of the unmanned boat.

[0037] Specifically, the motion equation of the unmanned boat on the sea surface is as follows:

[0038] Here represents the speed of the unmanned boat; represents the acceleration of the unmanned boat; represents the control input of the unmanned boat; respectively represent the inertia matrix, damping matrix, and Coriolis and centrifugal force matrices of the unmanned boat; represents the sea surface environmental disturbance acting on the unmanned boat.

[0039] To keep itself in the attitude level during navigation, it is necessary to design stabilizing controllers for its three attitude directions respectively. When no coupling control is performed, the controlled object in each attitude direction is in the following form:

[0040] where, , , and are respectively the equivalent inertia parameter, equivalent damping parameter, equivalent Coriolis and centrifugal force parameter, and equivalent disturbance parameter in the single-degree-of-freedom independent control scenario.

[0041] To simplify the analysis and control design, the system state is defined as , that is , representing the angular velocity of the unmanned boat, represents the angular acceleration. The nonlinear part, dynamic time-varying characteristics, and disturbances existing in the system during operation in the system dynamic equation in this attitude direction are integrated into the total disturbance , and is expanded into a new system state . At this time, the system is expanded into the following form:

[0042] In the formula, represents the system state variable, and physically it is ; represents the total disturbance 's rate of change.

[0043] The following form of a third-order linear extended state observer (the first extended state observer) can be used to estimate and observe the expanded system:

[0044] Here is the ESO observable of the system state ; is the observation error; is the observer gain, is the control input of the unmanned boat. Define:

[0045] The following form of linear feedback control law can be used. , where are the feedback gain coefficients:

[0046] Considering the ESO system constructed for the system, under the assumption that the total disturbance is continuously differentiable, when and , it can be guaranteed that the error system of this observer is asymptotically stable.

[0047] When designing the control parameters of the ESO and the error feedback law, based on the separation principle of active disturbance rejection control (ADRC), that is, first design the extended state observer and the error feedback law respectively based on the system response, and then adjust the parameters according to the complete closed-loop system.

[0048] Considering the closed-loop system, the linear ESO system and the error feedback law. By adjusting the appropriate parameters and , it can be guaranteed that this closed-loop system is globally uniformly asymptotically stable. It can be understood that the adjustment principle of the control parameters and can be similar to the tuning process of the corresponding PD controller. By increasing to speed up the response and reduce the residual, and by increasing to speed up the response and reduce the overshoot, and the larger the system's relative stability is higher.

[0049] In this controller, increasing the observer gain can reduce the observation error of the extended state and improve the convergence speed of the observer, but the corresponding observer will be more sensitive to measurement noise.

[0050] The composite sine function can be used as the disturbance observation input, and the integral of the absolute value of the error and the difference of the coefficients of the first 5-order Fourier series can be used as the optimization objective function. The parameters of the first extended state observer are determined by the optimization algorithm to obtain the trained attitude controller of the unmanned boat.

[0051] Since the influence of the marine environment on the unmanned boat has a disturbance characteristic similar to a sine wave, the composite sine function can be used as the disturbance observation input during simulation training.

[0052] To enable the obtained ESO to have the ability to quickly estimate the system state, the integral of the absolute value of the error and the difference of the coefficients of the first 5-order Fourier series can be used as the optimization index :

[0053] Among them, is the time, and are respectively and observation error values that change with time; represents the order of the Fourier series; are the Fourier coefficients of the simulation composite sine function; are the Fourier coefficients of the observation output of the ESO; is the optimized weight factor.

[0054] Optionally, the initialization parameters of the first extended state observer can be determined according to the bandwidth of the first extended state observer. For example, during preliminary design, by approximately selecting , the problem of adjusting the observer parameters is converted into the selection of the bandwidth of the first extended state observer.

[0055] Optionally, the optimization algorithm is a genetic algorithm. The genetic algorithm can be used for offline optimization in the ESO parameter design, and the optimization variable is . Taking the above optimization index as the fitness function, after multiple generations of iterative optimization, the optimal parameters can be found.

[0056] According to a method for controlling the landing process of an unmanned boat-aircraft platform collaborative system provided by the present invention, the acquisition method of the vertical controller of the unmanned aircraft includes: Designing a second extended state observer based on the system dynamics equation of the unmanned aircraft in the vertical direction; Determining a linear feedback control law based on the second extended state observer; Taking the integral of the absolute value of the error as the optimization objective function, and determining the parameters of the second extended state observer through an optimization algorithm to obtain a trained vertical controller of the unmanned aircraft.

[0057] Specifically, as shown above, the main control direction of the unmanned aircraft during the landing process is the z vertical direction. The dynamics equation of the unmanned aircraft during landing is simplified as follows:

[0058]

[0059]

[0060] In the formula, and respectively represent the attitude and vertical motion speed of the unmanned aircraft; represents the mass of the unmanned aircraft; is the gravitational acceleration; Represents the total thrust generated by the fins of the UAV, and the fin rotation speed ; Represents the lift coefficient; Represents all the resultant forces other than gravity and lift generated by the UAV during the landing on the unmanned boat.

[0061] Integrate the non-linear part, dynamic time-varying characteristics existing in the system dynamics equation in this direction, and the disturbances existing in the system during operation into the total disturbance , and expand into a new system state , and at this time the system expands into the following form:

[0062] In the formula, Represents the vertical velocity of the UAV , Represents the vertical acceleration of the UAV ; Represents the total disturbance The rate of change of.

[0063] Similar to the design of the unmanned boat, use a third-order linear ESO (Second Extended State Observer) in the following form to estimate and observe the expanded system:

[0064] Here Is the ESO observable of the system state ; Is the observation error; Is the observer gain. Define:

[0065] In the formula, Is the landing height of the UAV.

[0066] The following form of linear feedback control law can be used, , Are the feedback gain coefficients:

[0067] Considering the ESO system constructed for the system, under the assumption that the total disturbance Is continuously differentiable, when And , it can be guaranteed that the error system of this observer is asymptotically stable.

[0068] When designing the control parameters of the ESO and the error feedback law, the separation principle of ADRC is adopted, that is, the design of the extended state observer and the error feedback law is completed based on the system response respectively, and then the parameters are adjusted according to the complete closed-loop system.

[0069] Consider the closed-loop system, the linear ESO system and the error feedback law. By adjusting appropriate parameters and , it can be ensured that this closed-loop system is globally uniformly asymptotically stable. It can be understood that the adjustment principle of the control parameters and can be similar to the tuning process of the corresponding PD controller. By increasing to accelerate the response and reduce the residual error, and by increasing to accelerate the response and reduce the overshoot, and the larger is, the higher the relative stability of the system is.

[0070] In this controller, increasing the observer gain can reduce the observation error of the extended state and improve the convergence speed of the observer, but the corresponding observer will be more sensitive to measurement noise.

[0071] The integral of the absolute value of the error can be used as the optimization objective function, and the parameters of the second extended state observer can be determined through an optimization algorithm to obtain the trained vertical controller of the UAV.

[0072] Since the sine characteristic of the UAV disturbance is not obvious enough, random disturbance can be used as the disturbance observation input during simulation training. It can use only the integral of the absolute value of the error as the optimization index :

[0073] where is time, and are the observed error values of and changing with time respectively; is the optimization weight factor.

[0074] Optionally, the initial parameters of the second extended state observer can be determined according to the bandwidth of the second extended state observer. For example, during the preliminary design, by approximately selecting , the parameter adjustment problem of the observer can be converted into the selection of the bandwidth of the second extended state observer.

[0075] Optionally, the optimization algorithm is a genetic algorithm. The genetic algorithm can be used for offline optimization in the ESO parameter design, and the optimization variable is , taking the above optimization metrics as the fitness function, through multiple generations of iterative optimization, the optimal parameters are found.

[0076] According to a method for controlling the landing process of an unmanned boat-aircraft platform collaborative system provided by the present invention, the acquisition method of the UAV contact controller includes: Based on the desired mass matrix, desired damping matrix, and desired stiffness matrix, determine the admittance control equation of the UAV; Based on the desired contact force only in the vertical direction, adjust the parameters of the desired mass matrix, desired damping matrix, and desired stiffness matrix of the admittance control equation to obtain the UAV contact controller.

[0077] Specifically, the admittance control equation of the UAV can be determined according to the desired mass matrix, desired damping matrix, and desired stiffness matrix, as shown in the following formula:

[0078] where, are respectively the desired mass matrix, desired damping matrix, and desired stiffness matrix of the UAV system that are positive definite and symmetric; is the desired contact position; is the desired contact force and moment during the UAV landing; is the contact force and moment between the actual UAV and the unmanned boat.

[0079] The desired mass matrix is used to control the dynamic response of the UAV; the desired damping matrix is used to control the damping characteristics of the UAV, reducing oscillations and overshoots; the desired stiffness matrix is used to determine the compliance of the UAV to the contact force.

[0080] Each Cartesian variable of the admittance control equation is independent. From the control objectives of the landing process, the only control degree of freedom is the landing vertical direction z. Except for the landing vertical direction z, affected by the actual environment, the control adjustment amounts in the other directions need to be small enough to avoid generating excessive contact forces. Therefore, is selected as , where is the preset desired contact pressing force.

[0081] To achieve compliant control, the selection of

[0082] is crucial for the stability of the system. When setting these matrices, it is necessary to adjust the virtual mass, virtual damping, and virtual stiffness parameters in each matrix according to the characteristics of the contact process.

[0083]

[0084] Among them, is the virtual mass parameter of the contact process; is the virtual damping parameter of the contact process; is the feedback gain coefficient.

[0085] Desired mass matrix represents the response inertia of the system in each direction. Increasing the virtual mass can make the system respond more smoothly when subjected to external disturbances; Desired damping matrix controls the damping effect of the system, which is used to reduce the oscillation of the system. An appropriate damping value helps to eliminate unnecessary oscillations during contact; Desired stiffness matrix controls the rigidity of the system. Excessive rigidity may cause the system to be too rigid, which is not conducive to compliant control. To generate a compliant motion under the contact action, the desired stiffness matrix of the system is set to be close to zero.

[0086] By using the admittance control equation, the UAV can achieve compliant control during the landing process. By adjusting the desired mass matrix, desired damping matrix and desired stiffness matrix, it is ensured that the contact force in the vertical direction can be accurately controlled during the contact process , while avoiding excessive contact forces in other directions. The UAV contact controller obtained by optimizing these parameters can ensure that the UAV can land compliantly and smoothly when contacting the USV.

[0087] The following further elaborates on the landing process control method of the USV-UAV platform collaborative system provided by the present invention through examples in specific application scenarios.

[0088] Figure 2 is the overall flow schematic diagram of the USV-UAV platform collaborative landing control design provided by the present invention. As Figure 2 shown, it includes three main modules: USV-UAV platform collaborative system modeling; USV attitude control law design; UAV landing control law design.

[0089] Figure 3 is the complete control flow schematic diagram of the USV-UAV platform collaborative provided by the present invention. The following elaborates on each module of this embodiment in combination with Figures 2-3 this.

[0090] S1: USV-UAV platform collaborative system modeling The design process is elaborated as follows: It is studied that the UAV is a four-wing structure UAV, and the problem is the landing control problem of the UAV on the USV, that is, to achieve a soft landing of the UAV on the USV platform with strong robustness. The motion equation of the UAV is as follows:

[0091]

[0092] Here, represents the Cartesian position and velocity of the UAV in the global coordinate system; represents the gravity term of the UAV; represents the total thrust generated by the UAV's fins; represents all the resultant forces other than gravity and lift generated by the UAV when landing on the USV.

[0093] The attitude equation of the UAV is as follows:

[0094] Here, respectively represent the yaw angle , pitch angle and roll angle ; represents the angular velocity in the UAV's own coordinate system; represents the output torque generated by the four fins; represents the inertia matrix of the quadrotor; represents the mapping between the angular velocity and the Euler angle rate of change:

[0095] Lift and the output torque are related to the fin rotational speed . Their relationship is as follows:

[0096] Here, respectively represent the components of the output torque on the x, y, and z axes; and respectively represent the lift coefficient and the drag coefficient; represents the length of the rotor. In the research system, the lengths of all rotors are the same. and are related by the rotation matrix :

[0097]

[0098] Here, represents the cosine calculation ; represents the sine calculation . The axis rotation order of is Z - Y - X.

[0099] The motion equations of the USV on the sea surface are as follows:

[0100] where represents the speed of the USV; represents the acceleration of the USV; represents the control input of the USV; represent the inertia matrix, damping matrix, and Coriolis and centrifugal force matrix of the USV, respectively; represents the sea surface environmental disturbance on the USV.

[0101] Generally speaking, during the landing process of the UAV on the USV on the sea surface, its ideal flight attitude should be horizontal, that is, the roll angle and pitch angle should be close to 0. This attitude control process can be achieved by the typical PD controller of the UAV itself. Therefore, its main motion is in the vertical z direction. Thus, the dynamic equation of the UAV during landing can be simplified as follows:

[0102]

[0103]

[0104] where and represent the attitude and vertical motion speed of the UAV, respectively; represents the mass of the UAV.

[0105] S2: USV Attitude Control Law Design As can be analyzed in Section S1, the control objective of the USV is to keep its own attitude horizontal during navigation. Therefore, stable controllers need to be designed for its three attitude directions respectively. When no coupled control is performed, the controlled object in each attitude direction is in the following form:

[0106] where , , and are the equivalent inertia parameter, equivalent damping parameter, equivalent Coriolis force and centrifugal force parameter, and equivalent disturbance parameter in the single-degree-of-freedom independent control scenario, respectively.

[0107] Denote , that is , representing the angular velocity of the unmanned boat. Integrate the nonlinear part, dynamic time-varying characteristics, and disturbances existing in the system during operation in the system dynamic equation in this attitude direction into the total disturbance , and take Expand to a new system state , at this time the system expands to the following form:

[0108] Use a third-order linear ESO in the following form to estimate and observe the expanded system:

[0109] Here is the ESO observation of the system state ; is the observation error; is the observer gain. Define:

[0110] And use the following form of linear feedback control law:

[0111] The controller constructed in this way has the following properties: 1. Consider the ESO system constructed for the system. Under the assumption that the total disturbance is continuously differentiable, when and , it can be guaranteed that the error system of this observer is asymptotically stable.

[0112] 2. Consider the closed-loop system, the linear ESO system and the error feedback law. By adjusting the appropriate parameters and , it can be guaranteed that this closed-loop system is globally uniformly asymptotically stable.

[0113] In this controller, increasing the observer gain can reduce the observation error of the expanded state and improve the convergence speed of the observer, but the corresponding observer will be more sensitive to measurement noise. During the preliminary design, by approximately selecting , the problem of adjusting the observer parameters can be converted into the selection of the observer bandwidth .

[0114] At the same time, the adjustment principle of the control parameters and can be similar to the tuning process of the corresponding PD controller. By increasing to speed up the response and reduce the residual, and by increasing to speed up the response and reduce the overshoot, and the larger the relative stability of the system is higher.

[0115] When designing the control parameters of the ESO and the error feedback law, the separation principle of ADRC is adopted, that is, the extended state observer and the error feedback law are designed based on the system response respectively first, and then the parameters are adjusted according to the complete closed-loop system. In the design of ESO parameters, the genetic algorithm is used for offline optimization, and the optimization variables are .

[0116] Since the influence of the marine environment on the USV has a disturbance characteristic similar to a sine wave, the composite sine function is used as the disturbance observation input during simulation training. In order to make the obtained ESO have the ability to quickly estimate the system state, the integral of the absolute value of the error and the coefficient difference of the first 5-order Fourier series are used as the optimization index :

[0117] where is the Fourier coefficient of the simulation composite sine function; is the Fourier coefficient of the ESO observation output; is the optimization weight factor.

[0118] S3: UAV Landing Control Law Design As analyzed in Section S1, the main control direction of the UAV during landing is the z vertical direction. The nonlinear part, dynamic time-varying characteristics and disturbances existing in the system in this direction in the system dynamics equation are integrated into the total disturbance , and is expanded into a new system state . At this time, the system is expanded into the following form:

[0119] Similar to the USV design, a third-order linear ESO in the following form is used to estimate and observe the expanded system:

[0120] Here is the ESO observation value of the system state ; is the observation error; is the observer gain. Define:

[0121] where is the landing height of the UAV, and the following linear feedback control law form is used:

[0122] So far, the design of the controller for the vertical UAV has been completed. The parameter tuning process can adopt a similar process to that of the USV attitude controller.

[0123] Since the sine characteristic of the UAV disturbance is not obvious enough, only the integral of the absolute value of the error is used as the optimization index. :

[0124] However, affected by factors such as sea waves, there will still be a certain control error in the attitude of the USV. Therefore, it is necessary to design a compliant controller in the attitude direction of the UAV to reduce the contact force and achieve the soft landing process of the UAV.

[0125] In the present invention, the admittance control during the UAV contact process is used to achieve compliant control in the attitude direction. The admittance control equation of the UAV is as follows:

[0126] Among them, is the desired contact force and moment during the UAV landing; is the actual contact force and moment between the UAV and the USV; are respectively the mass, damping, and stiffness matrices of the desired UAV system that are positive definite and symmetric.

[0127] Each Cartesian variable of the admittance control is independent. From the control objective of the landing process, the only control degree of freedom is the landing vertical direction z. Except for the landing vertical direction z, affected by the actual environment, the control adjustment amounts in the other directions need to be small enough to avoid generating excessive contact forces. Therefore, is selected as , where is the preset desired contact pressing force.

[0128] The settings of the control parameters are as follows:

[0129]

[0130] Among them, is the virtual mass parameter during the contact process; is the virtual damping parameter during the contact process; is the gain factor.

[0131] So far, the design of the controller for the collaborative landing process of the unmanned surface vehicle - UAV platform has been completed.

[0132] The control device for the landing process of the unmanned boat-aircraft platform collaborative system provided by the present invention will be described below. The control device for the landing process of the unmanned boat-aircraft platform collaborative system described below can be correspondingly referred to the control method for the landing process of the unmanned boat-aircraft platform collaborative system described above.

[0133] Figure 4 It is a schematic structural diagram of the control device for the landing process of the unmanned boat-aircraft platform collaborative system provided by the present invention. As Figure 4 shown, the device includes the following modules: The unmanned boat control module 400 is used to control the target unmanned boat to maintain its attitude based on the unmanned boat attitude controller during the landing process of the target unmanned aircraft. The unmanned aircraft control module 410 is used to control the descent and soft landing process of the target unmanned aircraft on the target unmanned boat based on the unmanned aircraft vertical controller and the unmanned aircraft contact controller. The unmanned boat attitude controller and the unmanned aircraft vertical controller are obtained by training the extended state observer; the unmanned aircraft contact controller is obtained based on the admittance control equation.

[0134] According to a control device for the landing process of the unmanned boat-aircraft platform collaborative system provided by the present invention, the acquisition method of the unmanned boat attitude controller includes: Design a first extended state observer based on the motion equation of the unmanned boat; Determine the linear feedback control law based on the first extended state observer; Take the composite sine function as the disturbance observation input, and take the integral of the absolute value of the error and the difference of the coefficients of the first 5-order Fourier series as the optimization objective function, and determine the parameters of the first extended state observer through the optimization algorithm to obtain the trained unmanned boat attitude controller.

[0135] According to a control device for the landing process of the unmanned boat-aircraft platform collaborative system provided by the present invention, the acquisition method of the unmanned aircraft vertical controller includes: Design a second extended state observer based on the system dynamics equation of the unmanned aircraft in the vertical direction; Determine the linear feedback control law based on the second extended state observer; Take the integral of the absolute value of the error as the optimization objective function, and determine the parameters of the second extended state observer through the optimization algorithm to obtain the trained unmanned aircraft vertical controller.

[0136] According to a control device for the landing process of the unmanned boat-aircraft platform collaborative system provided by the present invention, the acquisition method of the unmanned aircraft contact controller includes: Determine the admittance control equation of the unmanned aircraft based on the expected mass matrix, the expected damping matrix and the expected stiffness matrix; Based on the desired contact force only in the vertical direction, adjust the parameters of the desired mass matrix, desired damping matrix, and desired stiffness matrix in the admittance control equation to obtain a UAV contact controller.

[0137] According to a control device for the landing process of an unmanned boat-aircraft platform collaborative system provided by the present invention, the initialization parameters of the first extended state observer are determined based on the bandwidth of the first extended state observer; and / or, the initialization parameters of the second extended state observer are determined based on the bandwidth of the second extended state observer.

[0138] According to a control device for the landing process of an unmanned boat-aircraft platform collaborative system provided by the present invention, the optimization algorithm is a genetic algorithm.

[0139] Figure 5 is a schematic structural diagram of an electronic device provided by the present invention, as Figure 5 shown, the electronic device may include: a processor 510, a communication interface 520, a memory 530, and a communication bus 540. Among them, the processor 510, the communication interface 520, and the memory 530 communicate with each other through the communication bus 540. The processor 510 can call the logical instructions in the memory 530 to execute the control method for the landing process of the unmanned boat-aircraft platform collaborative system, and the method includes: During the landing process of the target UAV, based on the unmanned boat attitude controller, control the target unmanned boat to maintain its attitude; Based on the UAV vertical controller and the UAV contact controller, control the descent and soft landing process of the target UAV on the target unmanned boat; The unmanned boat attitude controller and the UAV vertical controller are obtained by training the extended state observer; the UAV contact controller is obtained based on the admittance control equation.

[0140] In addition, when the logical instructions in the above-mentioned memory 530 are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs that can store program codes.

[0141] On the other hand, the present invention also provides a computer program product. The computer program product includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the landing process control method of the unmanned boat-aircraft platform cooperation system provided by the above-mentioned various methods. The method includes: During the landing process of the target unmanned aerial vehicle, based on the unmanned boat attitude controller, control the target unmanned boat to maintain its attitude; Based on the unmanned aerial vehicle vertical controller and the unmanned aerial vehicle contact controller, control the descent and soft landing process of the target unmanned aerial vehicle on the target unmanned boat; The unmanned boat attitude controller and the unmanned aerial vehicle vertical controller are obtained by training an extended state observer; the unmanned aerial vehicle contact controller is obtained based on the admittance control equation.

[0142] On another aspect, the present invention also provides a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it is implemented to execute the landing process control method of the unmanned boat-aircraft platform cooperation system provided by the above-mentioned various methods. The method includes: During the landing process of the target unmanned aerial vehicle, based on the unmanned boat attitude controller, control the target unmanned boat to maintain its attitude; Based on the unmanned aerial vehicle vertical controller and the unmanned aerial vehicle contact controller, control the descent and soft landing process of the target unmanned aerial vehicle on the target unmanned boat; The unmanned boat attitude controller and the unmanned aerial vehicle vertical controller are obtained by training an extended state observer; the unmanned aerial vehicle contact controller is obtained based on the admittance control equation.

[0143] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative efforts.

[0144] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on such an understanding, the essence of the above technical solution, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0145] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. And these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A control method for the landing process of an unmanned boat-aircraft platform collaborative system, characterized in that, Including: During the landing process of the target unmanned aerial vehicle (UAV), based on the unmanned boat attitude controller, controlling the target unmanned boat to maintain its attitude; Based on the UAV vertical controller and the UAV contact controller, controlling the descent and soft landing process of the target UAV on the target unmanned boat; The unmanned boat attitude controller and the UAV vertical controller are obtained by training an extended state observer; the UAV contact controller is obtained based on the admittance control equation.

2. The control method for the landing process of the unmanned boat-aircraft platform collaborative system according to claim 1, wherein The obtaining method of the unmanned boat attitude controller includes: Based on the motion equation of the unmanned boat, designing a first extended state observer; Based on the first extended state observer, determining a linear feedback control law; Taking the composite sine function as the disturbance observation input, and taking the integral of the absolute value of the error and the coefficient difference of the first 5-order Fourier series as the optimization objective function, and determining the parameters of the first extended state observer through an optimization algorithm to obtain the trained unmanned boat attitude controller.

3. The control method for the landing process of the unmanned boat-aircraft platform collaborative system according to claim 1, characterized in that The obtaining method of the UAV vertical controller includes: Based on the system dynamics equation of the UAV in the vertical direction, designing a second extended state observer; Based on the second extended state observer, determining a linear feedback control law; Taking the integral of the absolute value of the error as the optimization objective function, and determining the parameters of the second extended state observer through an optimization algorithm to obtain the trained UAV vertical controller.

4. The control method for the landing process of the unmanned boat-aircraft platform collaborative system according to claim 1, characterized in that The obtaining method of the UAV contact controller includes: Based on the desired mass matrix, the desired damping matrix, and the desired stiffness matrix, determining the admittance control equation of the UAV; Based on the desired contact force only in the vertical direction, adjusting the parameters of the desired mass matrix, the desired damping matrix, and the desired stiffness matrix of the admittance control equation to obtain the UAV contact controller.

5. The control method for the landing process of the unmanned boat-aircraft platform collaborative system according to claim 2 or 3, characterized in that, The initial parameters of the first extended state observer are determined based on the bandwidth of the first extended state observer; and / or, the initial parameters of the second extended state observer are determined based on the bandwidth of the second extended state observer.

6. The control method for the landing process of the unmanned boat-aircraft platform collaborative system according to claim 2 or 3, characterized in that, The optimization algorithm is a genetic algorithm.

7. A control device for the landing process of an unmanned boat-aircraft platform collaborative system, characterized in that, Including: An unmanned boat control module, configured to, during the landing process of the target UAV, based on the unmanned boat attitude controller, control the target unmanned boat to maintain its attitude; A UAV control module, configured to, based on the UAV vertical controller and the UAV contact controller, control the descent and soft landing process of the target UAV on the target unmanned boat; The unmanned boat attitude controller and the UAV vertical controller are obtained by training an extended state observer; the UAV contact controller is obtained based on the admittance control equation.

8. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the control method for the landing process of the unmanned boat - UAV platform cooperation system according to any one of claims 1 to 6.

9. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the control method for the landing process of the unmanned boat - UAV platform cooperation system according to any one of claims 1 to 6.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the control method for the landing process of the unmanned boat - UAV platform cooperation system according to any one of claims 1 to 6.

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