Methods, systems, devices, and media for submerging and hovering an underwater vehicle

Abstract

The application provides a method, system, device and medium for diving and hovering of an underwater vehicle, which integrates depth control, pitch control, lateral control and heading control into a sliding mode control framework, enhances the robustness of the system to parameter uncertainty and sea current disturbance, has clear control logic and strong engineering implementation, and establishes a control distribution matrix under the cooperative action of multiple propellers and rudders. In the diving stage, the front vertical propeller and the rear vertical propeller work cooperatively, and the forward propulsion and attitude are maintained in combination with the main propeller and the rudder. In the hovering stage, the front vertical propeller, the rear vertical propeller, the front lateral propeller and the rear lateral propeller output disturbance compensation force, which can fully exert the structural advantages of multiple propellers and rudders, and solve the technical problems of insufficient control efficiency in the diving and hovering working conditions, and difficulty in realizing high-precision depth keeping, point keeping and directional control.

Description

Technical Field

[0001] This invention belongs to the field of underwater robot and underwater navigation control technology, specifically relating to a method for diving and hovering of a multi-thrust underwater vehicle based on sliding mode control, and particularly to a method, system, device and medium for diving and hovering of an underwater vehicle. Background Technology

[0002] With the increasing demand for tasks such as marine environmental monitoring, underwater reconnaissance, underwater fixed-point observation, underwater target identification, and seabed facility inspection, rotary-body underwater vehicles are widely used due to their streamlined shape, low drag, high speed, and compact structure. Traditional torpedo-type rotary-body vehicles typically use the main propulsion unit and tail rudder as the primary control mechanisms, suitable for cruise and heading control, but they have significant limitations when performing tasks such as diving, low-speed hovering, and attitude control against currents.

[0003] On the one hand, the control method relying solely on the main thruster and rudder is inherently more suitable for generating lift and steering torque through rudder effect when the aircraft is operating at a certain forward speed. When the aircraft is operating at low speed or even close to zero speed, the hydrodynamic effect of the rudder is significantly weakened, resulting in a decrease in depth control, pitch control, and lateral stationary capability, making it difficult to achieve high-precision hovering and attitude maintenance in complex water flow environments.

[0004] On the other hand, the actual underwater environment is highly uncertain. Hydrodynamic parameters vary with speed, attitude, angle of attack, and external disturbances. Factors such as ocean currents, turbulence, and additional damping can all lead to model mismatch. When using conventional PID control or linearization control methods, the system is prone to problems such as large overshoot, large steady-state error, long settling time, and poor disturbance rejection under a wide range of operating conditions and external disturbances, making it difficult to meet the requirements of high-precision diving and hovering control.

[0005] To overcome the shortcomings of traditional underwater vehicles (UVs) such as reduced rudder effectiveness at low speeds and insufficient accuracy in hovering attitude adjustment, researchers have recently added vertical and lateral thrusters to some rotary-body UV vehicles. These additional propulsion mechanisms output direct force, thereby improving motion control during low-speed navigation and hovering. However, for rotary-body UV vehicles equipped with main thrusters, rudders, forward and aft vertical thrusters, and forward and aft lateral thrusters, existing research still has significant shortcomings: a complete control system solution adapted for diving and hovering operations has not yet been developed. Most studies only conduct dynamic modeling or controller design in isolation, severing the intrinsic connection between model derivation, sliding mode controller design and actuator allocation. They lack a systematic implementation scheme that covers the entire chain, including dynamic modeling, sliding mode surface optimization construction, anti-interference control law derivation, multi-actuator control allocation strategy design and simulation verification. It is difficult to coordinate the reasonable allocation of control output torque among the main thruster, rudder, and lateral-vertical auxiliary thrusters. Under the influence of external ocean current disturbances, the hovering position of the vehicle and attitude oscillation during the diving process are prominent problems, which restrict the practical application of this type of multi-thrust underwater vehicle in engineering. Summary of the Invention

[0006] To address the problems of insufficient low-speed control capability, poor hovering accuracy, weak disturbance rejection, and significant model uncertainty in existing technologies for the diving and hovering of multi-thrust underwater vehicles, this invention provides a method, system, device, and medium for the diving and hovering of underwater vehicles.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] In a first aspect, embodiments of this disclosure provide a method for underwater vehicles to dive and hover, comprising the following steps:

[0009] Step S1: Establish a six-degree-of-freedom kinematic model and a six-degree-of-freedom dynamic model of the underwater vehicle in the Earth-fixed coordinate system and the Body-fixed coordinate system;

[0010] Step S2: Based on the control requirements of the underwater vehicle under diving and hovering conditions, extract the longitudinal motion subsystem and the lateral motion subsystem from the six-degree-of-freedom kinematic model and the six-degree-of-freedom dynamic model. The longitudinal motion subsystem includes at least depth, vertical velocity, pitch angle and pitch angular velocity, and the lateral motion subsystem includes at least lateral displacement, lateral velocity, heading angle and heading angular velocity.

[0011] Step S3: Obtain the actual state information of the underwater vehicle based on the longitudinal motion subsystem and the lateral motion subsystem, and set the desired state information based on the diving mission. Construct depth error, pitch error, lateral position error and heading error based on the actual state information and the desired state information, respectively. Construct a depth sliding surface based on the depth error, a pitch sliding surface based on the pitch error, a lateral sliding surface based on the lateral position error, and a heading sliding surface based on the heading error. The actual state information includes actual depth, actual pitch angle, actual lateral position and actual heading angle. The desired state information includes desired depth trajectory, desired pitch angle trajectory, desired lateral position and desired heading angle.

[0012] Step S4: Using the longitudinal motion subsystem and the lateral motion subsystem as the controlled objects, and the depth sliding surface, pitch sliding surface, lateral sliding surface and heading sliding surface as feedback variables, set the sliding control laws for the depth, pitch, lateral and heading control channels respectively, and generate the expected generalized control force and torque for each channel based on the sliding control laws.

[0013] Step S5: Based on the interaction between the actuators and the degrees of freedom of the underwater vehicle, establish the control allocation relationship. Based on the control allocation matrix, allocate the desired generalized control force and torque, assign actual commands to each thruster and rudder, and control the underwater vehicle during the diving and hovering phases based on the actual commands.

[0014] Furthermore, the six-degree-of-freedom kinematic model include:

[0015] ;

[0016] In the formula, Let be the position and attitude vectors in the Earth-fixed coordinate system. ) represents the horizontal position coordinate in the Earth-fixed coordinate system, and z represents the depth in the Earth-fixed coordinate system. () is the attitude vector in the Earth-fixed coordinate system. This represents the matrix transpose operator, where This refers to the roll angle; The pitch angle; For heading angle; Let the linear velocity vector and angular velocity vector be in the body-fixed coordinate system. ) is the linear velocity vector in the body-fixed coordinate system, where The longitudinal velocity in the body-fixed coordinate system; The lateral velocity in the body-fixed coordinate system; The vertical velocity in the body-fixed coordinate system; ) is the angular velocity vector in the body-fixed coordinate system, where This refers to the roll angular velocity; It is the pitch angular velocity; Yaw angular velocity; This is the coordinate transformation matrix determined by the attitude angle;

[0017] The six-degree-of-freedom dynamic model includes:

[0018] ;

[0019] In the formula, , The inertia matrix of a rigid body. For the additional mass matrix; Let be the linear and angular velocity vectors of the vehicle in its six degrees of freedom; Let be the linear and angular acceleration vectors of the vehicle in its six degrees of freedom; Coriolis and centrifugal matrices; Here is the damping matrix; This is the vector of restoring forces caused by gravity and buoyancy; To control the input vector; This represents the environmental disturbance vector.

[0020] Furthermore, the longitudinal motion subsystem The state vector includes:

[0021] ;

[0022] In the formula, For longitudinal motion subsystem, The depth in the Earth-fixed coordinate system. The vertical velocity in the body-fixed coordinate system. The pitch angle, It is the pitch angular velocity;

[0023] The longitudinal motion subsystem The longitudinal generalized control input is:

[0024] ;

[0025] In the formula, To generate the combined vertical thrust of the fore and aft vertical thrusters of the underwater vehicle. The pitch control moment is formed by the combined action of the front and rear vertical thrusters and the rudder of the underwater vehicle;

[0026] Based on the six-degree-of-freedom dynamic model, the longitudinal motion subsystem Represented in state-space form :

[0027] ;

[0028] In the formula, The inherent dynamics of the longitudinal motion subsystem include the effects of mass and added mass, Coriolis force and centripetal force, fluid damping, gravity and buoyancy recovery, and the coupling between depth motion and pitch motion. The longitudinal control input matrix is ​​used to characterize the relationship between the combined vertical thrust and the combined pitch control moment on each longitudinal state variable; The longitudinal composite perturbation term includes at least the flow perturbation, model parameter perturbation, unmodeled dynamics, and coupled perturbations caused by neglected degrees of freedom, and is introduced by the longitudinal composite perturbation term.

[0029] Lateral motion subsystem The state vector includes:

[0030] ;

[0031] In the formula, This represents the actual lateral position of the underwater vehicle in a ground-fixed coordinate system. Let be the lateral velocity in the body-fixed coordinate system. For heading angle, Angular velocity of heading;

[0032] The lateral generalized control input of the lateral motion subsystem is:

[0033] ;

[0034] In the formula, The combined lateral thrust acting on the lateral degree of freedom is formed by the front lateral thruster and the rear lateral thruster. The combined yaw control torque acting on the yaw degree of freedom is formed by the differential thrust of the front and rear lateral thrusters and is adjusted in conjunction with the yaw torque generated by the rudder.

[0035] Based on the six-degree-of-freedom dynamic model, the lateral motion subsystem Represented in state-space form :

[0036] ;

[0037] In the formula, For the intrinsic dynamics of the lateral motion subsystem, This is the lateral control input matrix. The lateral composite perturbation term includes at least lateral flow perturbation, model parameter perturbation, unmodeled dynamics, and coupled perturbation of longitudinal motion on lateral motion.

[0038] Furthermore, a depth sliding surface is constructed based on the depth error and its derivative. Deep sliding surface include:

[0039] ;

[0040] In the formula, For depth tracking error, , For actual depth, For the desired depth; For depth tracking error The derivative; For the parameters of the depth sliding surface, ;

[0041] Pitch sliding surface constructed based on pitch error and its derivative. Pitch sliding surface include:

[0042] ;

[0043] In the formula, For pitch angle tracking error, , This is the actual pitch angle. The desired pitch angle; For pitch angle tracking error The derivative; For pitch sliding surface parameters, ;

[0044] Constructing the transverse sliding surface based on the transverse position error and its derivative. Horizontal sliding surface include:

[0045] ;

[0046] In the formula, This is the lateral position error. , This refers to the actual horizontal position. The desired lateral position; For the transverse sliding surface parameters, ;

[0047] Constructing the heading sliding surface based on the derivatives of heading error and lateral position error yaw sliding surface include:

[0048] ;

[0049] In the formula, This is the lateral position error. , This is the actual heading angle. The desired heading angle; For the heading sliding surface parameters, .

[0050] Furthermore, sliding mode control law include:

[0051] ;

[0052] In the formula, For sliding mode control law, For equivalent control items, To switch control items, , To switch the gain matrix, , For corresponding sliding surfaces, including depth sliding surfaces Pitch sliding surface Horizontal sliding surface and yaw sliding surface ; Boundary layer thickness, ; It is a saturation function.

[0053] Furthermore, the sliding mode control laws for each control channel include:

[0054] ;

[0055] In the formula, For the first The expected generalized control quantity for each control channel, For equivalent control items, To switch control items, To control the channel;

[0056] Among them, the equivalent control item ;

[0057] In the formula, For the first Control gain function for each control channel; The second derivative of the desired state; This represents the state vector of the corresponding motion subsystem; This is the desired state; For nominal dynamics; These are the parameters of the sliding surface; For tracking error;

[0058] The switching control item ;

[0059] In the formula, To switch gain, For linearly approaching gain, Boundary layer thickness; It is a saturation function. ;

[0060] In the formula, It is a saturation function. For the first Sliding mode variables for each control channel To correspond to the boundary layer thickness, It is a symbolic function;

[0061] The difference between the first and second derivatives of the desired depth, desired pitch angle, desired lateral position, and desired heading angle with respect to time in each channel is used as the state deviation. The sliding mode control law generates a compensating desired vertical generalized control force in real time based on the state deviation and external disturbances. Desired pitch generalized control torque Expected lateral generalized control and expected generalized control over the course It is used to maintain the depth, pitch, lateral position and heading of an underwater vehicle;

[0062] The desired vertical generalized control force of the depth control channel is:

[0063] ;

[0064] In the formula, For the desired vertical control force, The control gain function for the depth control channel. This is the state vector of the longitudinal motion subsystem. For the desired depth, The second derivative of the desired depth, For the nominal dynamics term of the depth channel, For the parameters of the depth sliding surface, For depth tracking error, To switch gain, Boundary layer thickness, For linearly approaching gain, For depth sliding mode variables, It is a saturation function;

[0065] The desired pitch generalized control torque of the pitch control channel is:

[0066] ;

[0067] In the formula, To achieve the desired pitch control torque, The control gain function for the pitch control channel. This is the state vector of the longitudinal motion subsystem. For the desired pitch angle, Let the second derivative be the desired pitch angle. For the nominal dynamics of the pitch channel, For pitch sliding surface parameters, For pitch angle tracking error, To switch gain, Boundary layer thickness, For linearly approaching gain, For pitch sliding mode variables, It is a saturation function;

[0068] The desired lateral generalized control force of the lateral control channel is:

[0069] ;

[0070] In the formula, To achieve the desired lateral control, This is the control gain function for the lateral control channel. This is the state vector of the lateral motion subsystem. For the desired lateral position, Let the second derivative be the desired lateral position. For the nominal dynamics term of the transverse channel, For the transverse sliding surface parameters, For lateral position tracking error, To switch gain, Boundary layer thickness, For linearly approaching gain, For lateral sliding mode variables, It is a saturation function;

[0071] The desired generalized heading control torque of the heading control channel is:

[0072] ;

[0073] In the formula, For the desired heading control torque, The control gain function for the heading control channel. This is the state vector of the lateral motion subsystem. For the desired heading angle, Let the second derivative of the desired heading angle be... For the nominal dynamics term of the heading channel, For the heading sliding surface parameters, For heading angle tracking error, To switch gain, Boundary layer thickness, For linearly approaching gain, For the heading sliding mode variable, It is a saturation function;

[0074] The desired generalized control force and torque for each channel are generated based on the sliding mode control law. ,include:

[0075] ;

[0076] In the formula, For longitudinal expectation generalized control force; For the expected generalized control torque during roll; This represents the matrix transpose operation.

[0077] Furthermore, the actuator includes at least a front vertical thruster, a rear vertical thruster, a front lateral thruster, a rear lateral thruster, a main thruster, and a rudder.

[0078] Control allocation relationships include:

[0079] ;

[0080] In the formula, For actuator command vectors; To control the allocation matrix;

[0081] Wherein, the actuator instruction vector include:

[0082] ;

[0083] In the formula, Main thruster thrust, and These are the thrust from the front vertical thruster and the thrust from the rear vertical thruster, respectively. and These are the thrust from the front lateral thruster and the thrust from the rear lateral thruster, respectively. This refers to the deflection angle of the rudder.

[0084] The control allocation matrix include:

[0085] ;

[0086] in, The coefficient of influence of the main thruster on the longitudinal control force; The coefficient of influence of the forward vertical thruster on the vertical control force; The coefficient of influence of the rear vertical thruster on the vertical control force; This is the coefficient of influence of the forward lateral thruster on the lateral control force; This is the coefficient of influence of the rear lateral thruster on the lateral control force; The longitudinal lever arm of the forward vertical thruster relative to the center of gravity; The longitudinal lever arm of the rear vertical thruster relative to the center of gravity; The longitudinal lever arm of the forward lateral thruster relative to the center of gravity; The longitudinal lever arm of the rear lateral thruster relative to the center of gravity; , , , , and All are hydrodynamic coefficients of the rudder deflection on the corresponding six degrees of freedom;

[0087] Based on the aforementioned control allocation relationship, the desired vertical generalized control force is obtained. Desired pitch generalized control torque Expected lateral generalized control and expected generalized control over the course At least the following conditions must be met:

[0088] ;

[0089] ;

[0090] ;

[0091] ;

[0092] The initial actuator instruction is determined using the weighted generalized inverse method:

[0093] ;

[0094] In the formula, This is the initial instruction vector without considering actuator constraints. To control the weighted generalized inverse of the allocation matrix, The desired generalized control force vector;

[0095] in:

[0096] ;

[0097] In the formula, It is a weighted generalized inverse matrix; Use a cost-weight matrix for the implementing agency; To control the allocation matrix; This represents the matrix transpose operation; The regularization coefficient is . ; It is the identity matrix;

[0098] Command to the initial actuator By applying amplitude and rate of change constraints, the actual issued instructions are obtained. For the first A single actuator, wherein the amplitude constraint is expressed as:

[0099] ;

[0100] In the formula, For the first Constrained instructions from each executing agency; For the first The minimum number of instructions allowed by an executing agency; For the first The maximum number of instructions allowed by each executing agency; Index for the executing agency;

[0101] The rate of change constraint is expressed as:

[0102] ;

[0103] In the formula, For the first The smallest instruction of an executing agency; For the first The maximum instruction of an executive agency; Maximum instruction change rate; To control the cycle;

[0104] If the actual instruction is issued When some actuators reach their upper or lower output limits, calculate the control allocation residual. :

[0105] ;

[0106] In the formula, The desired generalized control force vector; To control the allocation matrix; This refers to the actuator command vector after applying amplitude and rate of change constraints.

[0107] The control allocation residual The reallocation among unsaturated actuators enables the actual generalized control output. Approximate to the desired generalized control force vector .

[0108] In a second aspect, embodiments of this disclosure provide a system for the diving and hovering of an underwater vehicle, comprising:

[0109] The initialization unit is configured to establish a six-degree-of-freedom kinematic model and a six-degree-of-freedom dynamic model of the underwater vehicle in both the geo-fixed and body-fixed coordinate systems.

[0110] The extraction unit is configured to extract a longitudinal motion subsystem and a lateral motion subsystem from a six-degree-of-freedom kinematic model and a six-degree-of-freedom dynamic model according to the control requirements of the underwater vehicle in the diving and hovering conditions. The longitudinal motion subsystem includes at least depth, vertical velocity, pitch angle and pitch rate, and the lateral motion subsystem includes at least lateral displacement, lateral velocity, heading angle and heading rate.

[0111] The error unit is configured to acquire the actual state information of the underwater vehicle based on the longitudinal motion subsystem and the lateral motion subsystem, and set the desired state information based on the diving mission. Based on the actual state information and the desired state information, it constructs depth error, pitch error, lateral position error and heading error respectively. It constructs a depth sliding surface based on the depth error, a pitch sliding surface based on the pitch error, a lateral sliding surface based on the lateral position error, and a heading sliding surface based on the heading error. The actual state information includes actual depth, actual pitch angle, actual lateral position and actual heading angle. The desired state information includes desired depth trajectory, desired pitch angle trajectory, desired lateral position and desired heading angle.

[0112] The control law unit is configured to take the longitudinal motion subsystem and the lateral motion subsystem as the controlled objects, and the depth sliding surface, pitch sliding surface, lateral sliding surface and yaw sliding surface as feedback variables, respectively set the sliding control laws for the depth, pitch, lateral and yaw control channels, and generate the expected generalized control force and torque for each channel based on the sliding control laws.

[0113] The distribution unit is configured to establish a control distribution relationship based on the interaction between the actuators and the degrees of freedom of the underwater vehicle, to control and distribute the desired generalized control force and torque based on the control distribution matrix, to distribute actual commands to each thruster and rudder, and to control the underwater vehicle during the diving and hovering phases based on the actual commands.

[0114] In a third aspect, embodiments of this disclosure provide an electronic device, characterized in that the electronic device comprises:

[0115] At least one processor; and,

[0116] The memory is communicatively connected to the at least one processor; wherein,

[0117] The memory stores instructions that can be executed by the at least one processor to enable the at least one processor to perform the method of underwater vehicle diving and hovering.

[0118] In a fourth aspect, embodiments of this disclosure provide a non-transitory computer-readable storage medium, characterized in that the non-transitory computer-readable storage medium stores computer instructions for causing the computer to perform the method of underwater vehicle diving and hovering.

[0119] Compared with the prior art, the present invention has the following beneficial technical effects:

[0120] This invention provides a method, system, device, and medium for underwater vehicle diving and hovering. This method integrates depth control, pitch control, lateral control, and heading control into a sliding mode control framework, enhancing the system's robustness to parameter uncertainties and ocean current disturbances. The control logic is clear and highly feasible in engineering. Simultaneously, a control allocation matrix is ​​established based on the coordinated action of multiple thrusters and rudders. During the diving phase, the forward and rear vertical thrusters work together, combined with the main thruster and rudders to maintain forward propulsion and attitude. During the hovering phase, the forward, rear, forward, and rear lateral thrusters output compensation forces to compensate for disturbances. This fully leverages the structural advantages of multiple thrusters and rudders, solving the technical problems of insufficient control efficiency and difficulty in achieving high-precision depth, point, and direction control during diving and hovering. Attached Figure Description

[0121] Figure 1 A flowchart illustrating a method for underwater vehicles to dive and hover according to an embodiment of this disclosure is shown.

[0122] Figure 2 A diagram of an apparatus for a method of underwater vehicle diving and hovering according to an embodiment of the present disclosure is shown. Detailed Implementation

[0123] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0124] Figure 1 A flowchart 100 of a method for underwater vehicle diving and hovering, as disclosed in the first embodiment of this application, is shown. Figure 1 As shown, it includes the following steps:

[0125] It should be noted that, in this embodiment, the underwater vehicle is a torpedo-type rotating structure, including a main thruster, a rudder, a front vertical thruster, a rear vertical thruster, a front lateral thruster, and a rear lateral thruster, wherein:

[0126] The main thruster is used to provide longitudinal thrust;

[0127] The rudder is used to provide pitch and yaw control capabilities when forward velocity is present;

[0128] The front and rear vertical thrusters are used to directly generate the vertical resultant force and pitch control torque.

[0129] The front and rear lateral thrusters are used to directly generate lateral resultant force and yaw control torque.

[0130] In step S101, a six-degree-of-freedom kinematic model and a six-degree-of-freedom dynamic model of the underwater vehicle are established in the ground-fixed coordinate system and the body-fixed coordinate system.

[0131] Specifically, the six-degree-of-freedom kinematic model include:

[0132] ;

[0133] In the formula, Let be the position and attitude vectors in the Earth-fixed coordinate system. ) represents the horizontal position coordinate in the Earth-fixed coordinate system, and z represents the depth in the Earth-fixed coordinate system. () is the attitude vector in the Earth-fixed coordinate system. This represents the matrix transpose operator, where This refers to the roll angle; The pitch angle; For heading angle; Let the linear velocity vector and angular velocity vector be in the body-fixed coordinate system. ) is the linear velocity vector in the body-fixed coordinate system, where The longitudinal velocity in the body-fixed coordinate system; The lateral velocity in the body-fixed coordinate system; The vertical velocity in the body-fixed coordinate system; ) is the angular velocity vector in the body-fixed coordinate system, where This refers to the roll angular velocity; It is the pitch angular velocity; Yaw angular velocity; This is the coordinate transformation matrix determined by the attitude angle;

[0134] The six-degree-of-freedom dynamic model includes:

[0135] ;

[0136] In the formula, The total inertia matrix, , Let the inertia matrix be that of a rigid body. For the additional mass matrix; Let be the linear and angular velocity vectors of the vehicle in its six degrees of freedom; Let be the linear and angular acceleration vectors of the vehicle in its six degrees of freedom; The Coriolis and centrifugal matrices are defined by the combined effects of the rigid body and the added mass. Here is the damping matrix; This is the vector of restoring forces caused by gravity and buoyancy; To control the input vector; This represents the environmental disturbance vector.

[0137] Next, proceed to step S102.

[0138] In step S102, based on the control requirements of the underwater vehicle in the diving and hovering conditions, a longitudinal motion subsystem and a lateral motion subsystem are extracted from the six-degree-of-freedom kinematic model and the six-degree-of-freedom dynamic model. The longitudinal motion subsystem includes at least depth, vertical velocity, pitch angle and pitch angular velocity, and the lateral motion subsystem includes at least lateral displacement, lateral velocity, heading angle and heading angular velocity.

[0139] Specifically, from the six-degree-of-freedom kinematic model and six-degree-of-freedom dynamic model established in step S101, the longitudinal motion subsystem corresponding to depth-pitch control and the lateral motion subsystem corresponding to lateral position-heading control are extracted. It should be noted that the longitudinal and lateral motion subsystems aim to incorporate the effects of unmodeled roll motion, the coupling effect of forward velocity changes on vertical and pitch motion, and the coupling effect of roll motion on lateral and heading motion—all within permissible ranges and with forward velocity adjusted independently by the main thruster or used as measurable operating parameters in calculations—into the disturbance term. This reduces the dimensionality of the controller model required at the design level while preserving the main dynamic characteristics of the diving and hovering processes.

[0140] The longitudinal motion subsystem is used to describe the actual depth, vertical motion, and pitch motion of the underwater vehicle. The state vector of the longitudinal motion subsystem includes:

[0141]

[0142] In the formula, For longitudinal motion subsystem, This represents the actual depth of the underwater vehicle in a geofixed coordinate system. The vertical velocity in the body-fixed coordinate system. The pitch angle, The pitch angular velocity is denoted as . The above state variables respectively characterize the vertical position change, vertical motion trend, and longitudinal attitude change of the vehicle relative to the desired depth, providing actual state variables for the subsequent construction of depth and pitch errors.

[0143] The longitudinal generalized control input of the longitudinal motion subsystem is:

[0144]

[0145] In the formula, The combined vertical thrust acting on the vertical degree of freedom of the underwater vehicle is formed by the combined thrust of the front vertical thruster and the rear vertical thruster. The composite pitch control torque acting on the pitch degree of freedom is formed by the differential thrust of the front and rear vertical thrusters and the pitch torque generated by the rudder. Here... and The expected generalized control quantity at the controller output level is not the final command of each actuator; the thrust of each propeller and the deflection angle of the rudder are further obtained in step S105 based on the control allocation matrix.

[0146] Based on the aforementioned six-degree-of-freedom dynamic model, the longitudinal motion subsystem can be represented in the following state-space form:

[0147]

[0148] In the formula, It is the reciprocal of the longitudinal motion subsystem; The inherent dynamics of the longitudinal motion subsystem include the effects of mass and added mass, Coriolis force and centripetal force, fluid damping, gravity and buoyancy recovery, and the coupling between depth motion and pitch motion. The longitudinal control input matrix is ​​used to characterize the relationship between the combined vertical thrust and the combined pitch control moment on each longitudinal state variable; The longitudinal composite disturbance term includes at least water flow disturbance, model parameter perturbation, unmodeled dynamics, and coupled disturbance caused by neglected degrees of freedom. By introducing the longitudinal composite disturbance term, the longitudinal motion subsystem can cover the effects of buoyancy changes, external water flow, and actuator output deviations on control performance during diving and hovering.

[0149] The lateral motion subsystem is used to describe the lateral displacement, lateral motion, and heading motion of the underwater vehicle, and its state vector is:

[0150]

[0151] In the formula, This represents the actual lateral position of the underwater vehicle in a ground-fixed coordinate system. Let be the lateral velocity in the body-fixed coordinate system. For heading angle, The lateral state quantity is used to reflect the degree of offset of the vehicle relative to the desired lateral position and the change in heading attitude during hovering, providing actual state quantities for the subsequent construction of lateral position error and heading error.

[0152] The lateral generalized control input of the lateral motion subsystem is:

[0153]

[0154] In the formula, The combined lateral thrust acting on the lateral degree of freedom is formed by the front lateral thruster and the rear lateral thruster. The combined directional control torque acting on the directional degree of freedom is formed by the differential thrust of the forward and aft lateral thrusters and can be adjusted in conjunction with the directional torque generated by the rudder. Based on the aforementioned six-degree-of-freedom dynamic model, the lateral motion subsystem is represented in the following state-space form:

[0155]

[0156] In the formula, The reciprocal of the lateral motion subsystem, For the intrinsic dynamics of the lateral motion subsystem, This is the lateral control input matrix. The lateral composite perturbation term includes at least lateral flow perturbation, model parameter perturbation, unmodeled dynamics, and coupled perturbation of longitudinal motion on lateral motion.

[0157] Through the longitudinal and lateral motion subsystems, the six-degree-of-freedom kinematic model in step S101 can be transformed into a low-order state-space model corresponding to depth control, pitch control, lateral position control, and heading control. The longitudinal and lateral motion subsystems preserve the main states and their coupling relationships during descent and hovering, while simultaneously unifying the controller outputs as desired generalized thrust and desired generalized control torque, thus establishing the transmission relationship between "actual motion state—control error—sliding mode control quantity—actuator command".

[0158] Next, proceed to step S103.

[0159] In step S103, the actual information of the underwater vehicle is obtained based on the longitudinal motion subsystem and the lateral motion subsystem, and the expected information is set based on the diving mission. The depth error, pitch error, lateral position error and heading error are constructed based on the actual information and the expected information, respectively. A depth sliding surface is constructed based on the depth error, a pitch sliding surface is constructed based on the pitch error, a lateral sliding surface is constructed based on the lateral position error, and a heading sliding surface is constructed based on the heading error. The actual information includes the actual depth, actual pitch angle, actual lateral position and actual heading angle, and the expected information includes the expected depth trajectory, the expected pitch angle trajectory, the expected lateral position and the expected heading angle.

[0160] It should be noted that during the descent phase, the desired state information is a reference trajectory that changes over time, used to define the depth change process and attitude maintenance requirements of the underwater vehicle as it moves from the initial depth to the target depth; during the hovering phase, the desired depth, desired lateral position, desired pitch angle, and desired heading angle are target values ​​that remain unchanged, used to limit the position and attitude of the underwater vehicle in the target water area.

[0161] The depth tracking error is constructed based on the actual depth output by the longitudinal motion subsystem in step S102 and the desired depth trajectory:

[0162]

[0163] In the formula, For depth tracking error, This represents the actual depth corresponding to the longitudinal motion subsystem in step S102. The desired depth.

[0164] Taking the first derivative of the depth tracking error, we get:

[0165]

[0166] In the formula, Based on the state variables and kinematic relationships of the longitudinal motion subsystem in step S102, the following is obtained: Let be the first derivative of the desired depth trajectory.

[0167] Constructing a depth sliding surface based on depth tracking error and its first derivative:

[0168]

[0169] In the formula, For deep sliding surfaces, Let the parameters be the depth sliding surface parameters, and satisfy the following conditions: The depth sliding surface simultaneously characterizes the depth deviation and its changing trend.

[0170] When the depth sliding mode variable converges to the sliding mode surface and satisfies At that time, the depth tracking error dynamically satisfies:

[0171] In the formula, For depth tracking error, The depth sliding surface parameter; the dot above the symbol represents the first derivative with respect to time, and the zero on the right side of the equals sign indicates that the depth sliding variable has reached the sliding surface.

[0172] because The depth tracking error approaches zero exponentially along the depth sliding surface, thereby converting the actual depth state tracking requirement in step S102 into a depth sliding control target that can be directly used in step S104.

[0173] The pitch angle tracking error is constructed based on the actual pitch angle output by the longitudinal motion subsystem in step S102 and the desired pitch angle trajectory:

[0174]

[0175] In the formula, For pitch angle tracking error, This is the actual pitch angle. The desired pitch angle.

[0176] Taking the first derivative of the pitch angle tracking error, we get:

[0177]

[0178] In the formula, The pitch angular velocity and kinematic relationship of the longitudinal motion subsystem obtained in step S102 are used to obtain the following information. Let be the first derivative of the desired pitch angle trajectory.

[0179] Constructing a pitch sliding surface based on pitch angle tracking error and its first derivative:

[0180]

[0181] In the formula, For pitch sliding surface, Let these be the parameters of the pitch sliding surface, and satisfy... .

[0182] When the pitch sliding mode variable satisfies At that time, the pitch angle tracking error dynamically satisfies:

[0183]

[0184] In the formula, For pitch angle tracking error, The pitch sliding surface parameters are represented by a dot above the symbol, which indicates the first derivative with respect to time. The zero on the right side of the equals sign indicates that the pitch sliding variable has reached the sliding surface.

[0185] This causes the actual pitch angle to approach the desired pitch angle, and converts the pitch state and pitch angular velocity in step S102 into the control target required by the pitch control law in step S104.

[0186] Furthermore, a lateral position tracking error is constructed based on the actual lateral position output by the lateral motion subsystem in step S102 and the desired lateral position:

[0187]

[0188] In the formula, For lateral position tracking error, This refers to the actual horizontal position. The desired lateral position.

[0189] Taking the first derivative of the lateral position tracking error, we get:

[0190]

[0191] In the formula, The results are obtained based on the lateral velocity, attitude state, and kinematic relationships of the lateral motion subsystem in step S102. Let be the first derivative of the desired lateral position; when the desired lateral position is a fixed hovering position, it satisfies .

[0192] Constructing a transverse sliding surface based on the transverse position tracking error and its first derivative:

[0193]

[0194] In the formula, It is a transverse sliding surface. Let these be the parameters of the transverse sliding surface, and satisfy... .

[0195] When the lateral sliding mode variable satisfies At that time, the lateral position tracking error dynamically satisfies:

[0196]

[0197] In the formula, For lateral position tracking error, The parameter represents the transverse sliding surface; the dot above the symbol indicates the first derivative with respect to time, and the zero on the right side of the equals sign indicates that the transverse sliding variable has reached the sliding surface.

[0198] This makes the actual lateral position of the underwater vehicle approach the desired lateral position, and provides a control target for the lateral control law in step S104.

[0199] The heading angle tracking error is constructed based on the actual heading angle output by the lateral motion subsystem in step S102 and the desired heading angle:

[0200]

[0201] In the formula, For heading angle tracking error, This is the actual heading angle. The desired heading angle.

[0202] Taking the first derivative of the heading angle tracking error, we get:

[0203]

[0204] In the formula, The yaw rate and kinematic relationship of the lateral motion subsystem obtained in step S102 are used to obtain the results. Let be the first derivative of the desired heading angle; when the desired heading angle is a fixed value, it satisfies .

[0205] Constructing a heading sliding surface based on heading angle tracking error and its first derivative:

[0206]

[0207] In the formula, For the heading sliding surface, Let be the parameters of the heading sliding surface, and satisfy... .

[0208] When the heading sliding mode variable satisfies At that time, the dynamic tracking error of the heading angle satisfies:

[0209]

[0210] In the formula, For heading angle tracking error, The heading sliding surface parameter; the dot above the symbol represents the first derivative with respect to time, and the zero on the right side of the equals sign indicates that the heading sliding surface variable has reached the sliding surface.

[0211] This causes the actual heading angle of the underwater vehicle to approach the desired heading angle, and provides a control target for the heading control law in step S104.

[0212] Therefore, step S103 converts the motion state and dynamic information provided in step S102 into the sliding mode control variables required in step S104 according to the progressive hierarchy of "desired state setting - actual state acquisition - tracking error construction - error derivative calculation - sliding surface construction".

[0213] Next, proceed to step S104.

[0214] In step S104, the longitudinal motion subsystem and the lateral motion subsystem are taken as the controlled objects, and the depth sliding surface, pitch sliding surface, lateral sliding surface and heading sliding surface are taken as feedback variables. The sliding control laws of the depth, pitch, lateral and heading control channels are set respectively, and the expected generalized control force and torque of each channel are generated based on the sliding control laws.

[0215] Specifically, the longitudinal motion subsystem and the lateral motion subsystem established in step S102 are taken as the controlled objects, and the depth sliding surface constructed in step S103 is used as the controlled object. Pitch sliding surface Horizontal sliding surface and yaw sliding surface As feedback variables, sliding mode control laws are designed for the depth, pitch, lateral, and heading control channels respectively. Therefore, step S102 provides the dynamic description and control input for each control channel; step S103 converts the deviation between the actual state and the desired state into sliding mode variables; and step S104 calculates the desired generalized control force and desired generalized control torque based on the dynamic description and sliding mode variables, thus forming a progressive control relationship from the state model and error variables to the virtual control quantity.

[0216] For ease of consistent description, the controlled outputs of the four control channels—depth, pitch, lateral, and heading—are denoted as... Its expected output is denoted as ,in:

[0217] ;

[0218] In the formula, For the first The actual controlled status of each control channel For the corresponding expected state, For control channel index; , , and These are the actual depth, actual pitch angle, actual lateral position, and actual heading angle, respectively. , , and These represent the corresponding expected states.

[0219] Corresponding tracking error and sliding mode variables They are respectively:

[0220]

[0221] In the formula, , These are the sliding surface parameters corresponding to the control channel.

[0222] Based on the longitudinal dynamic subsystem and the lateral dynamic subsystem in step S102, the output dynamics directly related to the control input in each control channel are uniformly represented as follows:

[0223]

[0224] In the formula, Represents the state vector of the longitudinal motion subsystem Or the state vector of the lateral motion subsystem , State-space form representing the state vector of the longitudinal motion subsystem Or the state-space form of the lateral motion subsystem , These are known or computable dynamic terms consisting of inertial terms, Coriolis and centripetal force terms, damping terms, restoring force terms, and inter-channel coupling terms. The control gain for the corresponding control channel. For the desired generalized control quantity, It is a composite disturbance term consisting of model parameter perturbations, unmodeled coupling terms, and external water flow disturbances.

[0225] The expected generalized control quantity The correspondence between the four control channels is as follows:

[0226]

[0227] in, For the desired vertical control force, To achieve the desired pitch control torque, To achieve desired lateral control, The desired heading control torque.

[0228] For the sliding mode variable Taking the derivative, we get:

[0229] ;

[0230] In the formula, For the first Sliding mode variables for each control channel No. The reciprocal of the sliding mode variable of each control channel and These are the actual controlled state and the desired state, respectively. The second derivative of the actual controlled state with respect to the expected state is given by the second derivative. The second derivative of the desired state. For sliding surface parameters, To track errors, It is the reciprocal of the tracking error; a dot above the sign indicates the first derivative with respect to time, and two dots above the sign indicate the second derivative with respect to time.

[0231] Set the sliding mode control law of each control channel as the sum of the equivalent control term and the switching control term:

[0232]

[0233] In the formula, For the first The expected generalized control quantity for each control channel, For equivalent control items, To switch control items, To control the channel.

[0234] Wherein, the equivalent control item The nominal dynamics used to compensate for the nominal dynamics in step S102 and achieve desired trajectory tracking refer to the deterministic dynamics calculated by the dynamics model when using the nominal model parameters of the aircraft and ignoring model errors and external disturbances. However, these deterministic dynamics deviate from the actual dynamic parameters, so an equivalent control term is used. Error compensation includes:

[0235] ;

[0236] In the formula, For the first Control gain function of each control channel The second derivative of the desired state. For the state vector of the corresponding motion subsystem, For the desired state, For nominal dynamics, For sliding surface parameters, For tracking error;

[0237] The switching control item Used to suppress synthetic perturbations and model uncertainties, including:

[0238] ;

[0239] in, To switch gain, For linearly approaching gain, Boundary layer thickness; Let be a saturation function, and its expression is:

[0240] ;

[0241] In the formula, It is a saturation function. For the first Sliding mode variables for each control channel To correspond to the boundary layer thickness, It is a symbolic function.

[0242] By replacing discontinuous sign functions with continuous saturation functions near the sliding surface, the high-frequency switching of thruster thrust and rudder deflection angle can be reduced while maintaining the disturbance rejection capability of the control system.

[0243] In this embodiment, based on the sliding mode control law of each control channel, the desired vertical generalized control force of the depth control channel is:

[0244] ;

[0245] In the formula, For the desired vertical control force, The control gain function for the depth control channel. This is the state vector of the longitudinal motion subsystem. For the desired depth, The second derivative of the desired depth, For the nominal dynamics term of the depth channel, For the parameters of the depth sliding surface, For depth tracking error, To switch gain, Boundary layer thickness, For linearly approaching gain, For depth sliding mode variables, It is a saturation function;

[0246] The desired pitch generalized control torque for the pitch control channel is:

[0247] ;

[0248] In the formula, To achieve the desired pitch control torque, The control gain function for the pitch control channel. This is the state vector of the longitudinal motion subsystem. For the desired pitch angle, Let the second derivative be the desired pitch angle. For the nominal dynamics of the pitch channel, For pitch sliding surface parameters, For pitch angle tracking error, To switch gain, Boundary layer thickness, For linearly approaching gain, For pitch sliding mode variables, It is a saturation function;

[0249] The expected lateral generalized control force of the lateral control channel is:

[0250] ;

[0251] In the formula, To achieve desired lateral control, This is the control gain function for the lateral control channel. This is the state vector of the lateral motion subsystem. For the desired lateral position, Let the second derivative be the desired lateral position. For the nominal dynamics term of the transverse channel, For the transverse sliding surface parameters, For lateral position tracking error, To switch gain, Boundary layer thickness, For linearly approaching gain, For lateral sliding mode variables, It is a saturation function;

[0252] The desired generalized heading control moment for the heading control channel is:

[0253]

[0254] In the formula, For the desired heading control torque, The control gain function for the heading control channel. This is the state vector of the lateral motion subsystem. For the desired heading angle, Let the second derivative of the desired heading angle be... For the nominal dynamics term of the heading channel, For the heading sliding surface parameters, For heading angle tracking error, To switch gain, Boundary layer thickness, For linearly approaching gain, For the heading sliding mode variable, It is a saturation function;

[0255] When the desired depth, desired pitch angle, desired lateral position, and desired heading angle are all constant during the hovering phase, the following conditions are met:

[0256] ;

[0257] In the formula, For the desired depth, The first derivative of the desired depth, The second derivative of the desired depth, For the desired pitch angle, Let the first derivative be the desired pitch angle. Let be the second derivative of the desired pitch angle.

[0258] ;

[0259] In the formula, For the desired lateral position, Let the first derivative be the desired lateral position. Let the second derivative be the desired lateral position. For the desired heading angle, The first derivative of the desired heading angle. Let be the second derivative of the desired heading angle.

[0260] The difference between the first and second derivatives of the desired depth, desired pitch angle, desired lateral position, and desired heading angle with respect to time in each channel is taken as the state deviation. At this time, the sliding mode control law generates a compensatory desired vertical generalized control force in real time based on the state deviation and external disturbances. Desired pitch generalized control torque Expected lateral generalized control and expected generalized control over the course It is used to maintain the depth, pitch, lateral position and heading of an underwater vehicle.

[0261] The desired vertical generalized control force output in step S104 Desired pitch generalized control torque Expected lateral generalized control and expected generalized control over the course As a virtual generalized control quantity, it does not yet directly correspond to the execution command of a single thruster or rudder. In step S105, control allocation needs to be performed based on the installation position, direction of action, and output constraints of the actuator.

[0262] Next, proceed to step S105.

[0263] In step S105, a control allocation relationship is established based on the interaction between the actuators and the degrees of freedom of the underwater vehicle. Based on the control allocation matrix, the desired generalized control force and torque are allocated, and actual commands are assigned to each thruster and rudder. Based on the actual commands, the underwater vehicle is controlled during the diving and hovering phases.

[0264] Step S105 receives the desired vertical control force output in step S104. Desired pitch control torque Expected lateral control and desired heading control torque And determine the longitudinal control force based on the forward propulsion requirements during the diving phase. When no independent roll control channel is set, the roll control torque is... Set to zero, or as given by the roll hold controller.

[0265] The desired generalized control force and torque are expressed as follows:

[0266]

[0267] In the formula, For longitudinal expectation generalized control force; For the expected generalized control torque during roll; This represents the matrix transpose operation.

[0268] Based on the sliding mode control laws of the depth, pitch, lateral, and yaw control channels, the desired vertical generalized control force is generated respectively. Desired pitch generalized control torque Expected lateral generalized control and the desired generalized control torque of the heading Determine the expected longitudinal generalized control force based on the forward propulsion requirements of the underwater vehicle. This patent focuses on diving and hovering, therefore the longitudinal expected generalized control force is considered. Set to zero; no independent roll control channel is set, therefore the roll expectation generalized control torque is set to zero. Set to zero.

[0269] The actuator command vector is represented as follows:

[0270] ;

[0271] in, Main thruster thrust, and These are the thrust from the front vertical thruster and the thrust from the rear vertical thruster, respectively. and These are the thrust from the front lateral thruster and the thrust from the rear lateral thruster, respectively. This refers to the rudder deflection angle.

[0272] Based on the position vector, thrust direction vector, and hydrodynamic derivative of each actuator relative to the center of gravity of the underwater vehicle, the control allocation relationship is established:

[0273] ;

[0274] in, The control allocation matrix is ​​used for control. In a front-to-back symmetrical arrangement, the control allocation matrix can be represented as:

[0275] ;

[0276] in, The coefficient of influence of the main thruster on the longitudinal control force. and The coefficients representing the effects of the front and rear vertical thrusters on the vertical control force. and The coefficients representing the effect of the front and rear lateral thrusters on the lateral control force; and These are the longitudinal lever arms of the front and rear vertical thrusters relative to the center of gravity, respectively. and These are the longitudinal lever arms of the front and rear lateral thrusters relative to the center of gravity, respectively. , , , , and These are the hydrodynamic coefficients for the rudder deflection on the corresponding degree of freedom. The specific coefficients in the matrix are determined based on the underwater vehicle's actuator installation structure, the positive direction of the coordinate axes, and the hydrodynamic parameters.

[0277] Based on the aforementioned control allocation relationship, the desired vertical generalized control force is obtained. Desired pitch generalized control torque Expected lateral generalized control and expected generalized control over the course At least the following conditions must be met:

[0278] ;

[0279] In the formula, For the desired vertical control force, and These are the vertical action coefficients for the front and rear vertical thrusters, respectively. and These are the thrust from the front and rear vertical thrusters, respectively. The coefficient representing the effect of the rudder on the vertical control force. This refers to the rudder deflection angle.

[0280] ;

[0281] In the formula, To achieve the desired pitch control torque, and These are the longitudinal lever arms of the front and rear vertical thrusters relative to the center of gravity, respectively. and The vertical action coefficient, and For the thrust of the front and rear vertical thrusters, This is the coefficient of the effect of the rudder on the pitch control torque. This refers to the rudder deflection angle.

[0282] ;

[0283] In the formula, To achieve the desired lateral control, and These are the lateral action coefficients for the front and rear lateral thrusters, respectively. and These are the thrust from the front and rear lateral thrusters, respectively. The coefficient of the rudder's effect on the lateral control force. This refers to the rudder deflection angle.

[0284] ;

[0285] In the formula, For the desired heading control torque, and These are the longitudinal lever arms of the front and rear lateral thrusters relative to the center of gravity, respectively. and This is the horizontal effect coefficient. and For the thrust of the front and rear lateral thrusters, This is the coefficient of the rudder's effect on the heading control torque. This refers to the rudder deflection angle.

[0286] The initial actuator instruction is determined using the weighted generalized inverse method:

[0287] ;

[0288] In the formula, This is the initial instruction vector without considering actuator constraints. To control the weighted generalized inverse of the allocation matrix, Let be the desired generalized control force vector.

[0289] in:

[0290] ;

[0291] In the formula, It is a weighted generalized inverse matrix; Use a cost-weight matrix for the implementing agency; To control the allocation matrix; This represents the matrix transpose operation; The regularization coefficient is . ; It is an identity matrix.

[0292] By adjusting the cost weight matrix used by the implementing agency The diagonal elements can reduce the proportion of energy-intensive actuators or prioritize the use of faster-responding thrusters, while meeting the requirements of generalized control.

[0293] Initial actuator instructions By applying amplitude and rate of change constraints, the actual issued instructions are obtained. For the first A single actuator, wherein the amplitude constraint is expressed as:

[0294] ;

[0295] In the formula, For the first Constrained instructions from each executing agency and The first The minimum and maximum instructions allowed by each executing agency. Index for the executing agency.

[0296] The rate of change constraint is expressed as:

[0297] ;

[0298] in, and The first Minimum and maximum instructions for each execution unit. For the maximum instruction change rate, To control the cycle.

[0299] If the actual instruction is issued When some actuators reach their upper or lower output limits, calculate the control allocation residual. :

[0300] ;

[0301] In the formula, To control the allocation of residual vectors, For the desired generalized control force vector, To control the allocation matrix, The actuator command vector after applying amplitude and rate of change constraints.

[0302] Subsequently, the residuals will be allocated. The distribution among unsaturated actuators is made so that the actual generalized control output is... As close as possible to the desired generalized control force vector This avoids the decrease in depth, attitude, or lateral position control caused by continuous saturation of a single thruster.

[0303] Specifically, based on the actual issued instructions During the descent phase, the main thruster operates according to the longitudinal desired generalized control force. The forward thrust is output, and the forward and rear vertical thrusters together generate the desired vertical control force. The desired pitch control torque is generated through the thrust difference between the two. The rudder plate is adjusted according to the rudder plate deflection angle. The pitch attitude is adjusted, and the front and rear lateral thrusters are adjusted according to the desired lateral control force. and desired heading control torque Suppress lateral drift and heading deviation;

[0304] During the hovering phase, the main thruster thrust is reduced to zero or used to compensate for longitudinal water flow disturbances. The front and rear vertical thrusters output differential thrust according to depth and pitch control requirements, and the front and rear lateral thrusters output differential thrust according to lateral position and heading control requirements.

[0305] This embodiment also provides a simulation verification scheme for verifying the underwater vehicle's diving and hovering method described in this embodiment. Specifically, after step S105, the closed-loop control method consisting of steps S102 to S105 is simulated and verified. The simulation verification is used to check the matching and continuity of the subsystem model in step S102, the error and sliding surface in step S103, the sliding mode control law in step S104, and the control allocation relationship in step S105 in the same closed loop.

[0306] In the simulation environment, the initial longitudinal state and initial lateral state of the underwater vehicle are set, where the initial longitudinal state... include:

[0307] ;

[0308] In the formula, Let be the initial state vector of the longitudinal motion subsystem. , , and These are the initial actual depth, initial vertical velocity, initial actual pitch angle, and initial pitch angular velocity, respectively. This represents the matrix transpose operation.

[0309] The initial lateral state include:

[0310] ;

[0311] In the formula, This is the initial state vector of the lateral motion subsystem. , , and These are the initial actual lateral position, initial lateral velocity, initial actual heading angle, and initial heading angular velocity, respectively. This represents the matrix transpose operation.

[0312] Segmented expected depth trajectories are set based on the diving and hovering missions. :

[0313] ;

[0314] in, As the initial depth, To achieve the desired descent speed, Target hovering depth, The moment the dive begins. This marks the moment of entering the hovering phase. The desired pitch angle, desired lateral position, and desired yaw angle are set as follows: , and During the hovering phase, the expected value remains constant.

[0315] To verify the anti-disturbance capability of the underwater vehicle diving and hovering method described in this embodiment, time-varying disturbances were added to the longitudinal motion subsystem and the lateral motion subsystem, respectively:

[0316] ;

[0317] In the formula, For vertical composite perturbation, For constant vertical disturbance components, The amplitude of the periodic vertical disturbance. The vertical perturbation angular frequency, This represents the simulation time.

[0318] ;

[0319] in, and For constant disturbance components, and For the amplitude of the periodic disturbance, and The disturbance angular frequency is used. Step flow disturbances or parameter perturbations can also be applied at preset times to test the underwater vehicle's state recovery capability after switching from the diving phase to the hovering phase.

[0320] To reflect the dynamic response of the thruster and rudder, the actual output of the actuator is represented as a first-order inertial element:

[0321] ;

[0322] In the formula, For the first The actual thrust of each propeller Assign control instructions to it. The time constant of the first-order inertial element of the thruster. The symbol is the thruster index; the dot above the symbol indicates the first derivative with respect to time.

[0323] ;

[0324] in, and These are the thruster commands and rudder deflection commands obtained after control allocation, respectively. and The actual output of the executing agency, and This is the corresponding time constant.

[0325] Record the actual depth during the simulation. Actual pitch angle Actual lateral position Actual heading angle and the corresponding tracking error , , , Sliding mode variable , , , Expected generalized control force vector and executive orders The desired generalized control force vector is used to reflect the requirements of each control channel for the resultant force and resultant torque of the underwater vehicle in step S104, and the actuator command is used to reflect the realization of the desired generalized control force by each thruster thrust and rudder deflection angle in step S105.

[0326] To uniformly evaluate the tracking accuracy of the four control channels—depth, pitch, lateral, and yaw—let the control channel index... satisfy:

[0327] ;

[0328] In the formula, To control the channel index, , , and These represent the depth, pitch, lateral, and heading control channels, respectively.

[0329] Simulation duration for each control channel The maximum absolute error within is defined as:

[0330] ;

[0331] In the formula, For the first The maximum absolute error of each control channel within the simulation interval. For this control channel at time Tracking error, The total simulation duration is... This represents the simulation time.

[0332] The maximum absolute error is used to characterize the maximum transient deviation of the corresponding control channel during initial adjustment, trajectory switching, external disturbances, and hovering. The root mean square error of each control channel is defined as:

[0333] ;

[0334] In the formula, For the first The root mean square error of each control channel This is the tracking error of the control channel. The total simulation duration is... This represents the simulation time.

[0335] The root mean square error is used to comprehensively characterize the tracking accuracy throughout the entire simulation period, reflecting the impact of both transient and sustained errors on control performance. To further evaluate the steady-state holding capability during the hovering phase, a hovering stability evaluation interval is selected. And define the average steady-state absolute error:

[0336] ;

[0337] In the formula, The starting time when the underwater vehicle enters the hovering stability evaluation range, and satisfies the following conditions: The average steady-state absolute error is used to evaluate the static error and low-frequency fluctuations of an underwater vehicle when it maintains a position near the target depth and attitude for an extended period of time.

[0338] To evaluate the convergence of each sliding mode variable to the sliding surface, the root mean square value of the sliding mode variable is defined as follows:

[0339] ;

[0340] In the formula, For the first The root mean square value of the sliding mode variable for each control channel. For this control channel at time sliding mode variables, This represents the total simulation duration.

[0341] When the control channel is at time sliding mode variables Within a finite time, enter the bounded neighborhood near zero, and the... The root mean square value of sliding mode variables for each control channel When the value remains small, it indicates that the corresponding control channel can approach the sliding surface constructed in step S103 and maintain stable motion under the combined action of the equivalent control term and the switching control term described in step S104.

[0342] To evaluate the accuracy of the control allocation result in achieving the desired generalized control force, the control allocation matrix in step S105 is used as a reference. Define control allocation residual vector :

[0343] ;

[0344] In the formula, For a moment The control allocation of residual vectors, For the desired generalized control force vector, To control the allocation matrix, This is the constrained actuator command vector.

[0345] Further define the root mean square value of the control allocation residual:

[0346] ;

[0347] In the formula, To control the root mean square value of the allocated residuals, To control the allocation of residual vectors, The total simulation duration is... For simulation time, subscript The L2 norm of a vector is used to represent the vector's L2 norm.

[0348] The control allocation residual is used to characterize the deviation between the actual generalized control action obtained by combining the thrust of each propeller and the deflection angle of the rudder and the desired generalized control force. When the actuator does not reach its output limit, the root mean square value of the smaller control allocation residual is considered. This indicates that the control allocation results can accurately achieve the resultant force and resultant torque requirements given by the controller; when some actuators reach the thrust or deflection angle limits, the control allocation residual vectors before and after saturation are compared. The effectiveness of constraint handling and residual control capability reallocation in step S105 is evaluated.

[0349] make Indicates the first Instructions from an executive agency, If the total number of implementing agencies is represented, then the first... The peak instruction and root mean square instruction of each actuator are defined as follows:

[0350] ;

[0351] In the formula, For the first Peak value of each actuator command, For a moment The An executive agency instruction, The total simulation duration is... Index for the executing agency.

[0352] ;

[0353] In the formula, For the first The root mean square value of each actuator instruction. For the implementing agency at any time The instructions The total simulation duration is... The total number of implementing agencies, Index for the executing agency.

[0354] By the first Peak value of each actuator command The force is compared with the upper and lower limits of the allowable thrust of the corresponding actuator or the allowable deflection range of the rudder to determine whether the actuator command meets the physical constraints; through the first Peak value of each actuator command Evaluate the average control load of each actuator throughout the mission and analyze whether the load distribution between the front and rear vertical thrusters and between the front and rear lateral thrusters is reasonable.

[0355] To evaluate the smoothness of the execution mechanism's instructions, a total instruction variation index can be further defined. :

[0356] ;

[0357] In the formula, The total variation index for executing agency instructions. The total number of implementing agencies, For the first Each implementing agency at any time The instructions The total simulation duration is denoted by ; the integrand represents the absolute value of the first derivative of the actuator command with respect to time.

[0358] The total command variation index is used to characterize the frequency of changes in thruster thrust and rudder deflection during simulation. A smaller total command variation index is desirable when both tracking error and control allocation residual meet control requirements. This indicates that the changes in actuator commands are relatively smooth, which helps to reduce the high-frequency control effects caused by sliding mode control switching terms and reduce the energy consumption and mechanical load caused by frequent thruster adjustments.

[0359] Simulation results include curves comparing the desired and actual states, various tracking error curves, various sliding mode variable curves, desired generalized control force and torque curves, thrust curves for each propeller, rudder deflection angle curve, and control allocation residual curves. These curves and performance indicators verify that the underwater vehicle can track the desired depth trajectory and maintain pitch attitude during descent, smoothly transition from descent to hovering upon reaching the target depth, and maintain stability in depth, lateral position, pitch angle, and heading angle under external disturbances and actuator constraints. This verifies the progressive relationship and overall effectiveness between the modeling, error construction, sliding mode control, and control allocation methods established in steps S102 to S105.

[0360] The second embodiment of the present invention also provides a system for underwater vehicles to dive and hover, comprising:

[0361] The initialization unit is configured to establish a six-degree-of-freedom kinematic model and a six-degree-of-freedom dynamic model of the underwater vehicle in both the geo-fixed and body-fixed coordinate systems.

[0362] The extraction unit is configured to extract a longitudinal motion subsystem and a lateral motion subsystem from a six-degree-of-freedom kinematic model and a six-degree-of-freedom dynamic model according to the control requirements of the underwater vehicle in the diving and hovering conditions. The longitudinal motion subsystem includes at least depth, vertical velocity, pitch angle and pitch rate, and the lateral motion subsystem includes at least lateral displacement, lateral velocity, heading angle and heading rate.

[0363] The error unit is configured to acquire the actual state information of the underwater vehicle based on the longitudinal motion subsystem and the lateral motion subsystem, and set the desired state information based on the diving mission. Based on the actual state information and the desired state information, it constructs depth error, pitch error, lateral position error and heading error respectively. It constructs a depth sliding surface based on the depth error, a pitch sliding surface based on the pitch error, a lateral sliding surface based on the lateral position error, and a heading sliding surface based on the heading error. The actual state information includes actual depth, actual pitch angle, actual lateral position and actual heading angle. The desired state information includes desired depth trajectory, desired pitch angle trajectory, desired lateral position and desired heading angle.

[0364] The control law unit is configured to take the longitudinal motion subsystem and the lateral motion subsystem as the controlled objects, and the depth sliding surface, pitch sliding surface, lateral sliding surface and yaw sliding surface as feedback variables, respectively set the sliding control laws for the depth, pitch, lateral and yaw control channels, and generate the expected generalized control force and torque for each channel based on the sliding control laws.

[0365] The distribution unit is configured to establish a control distribution relationship based on the interaction between the actuators and the degrees of freedom of the underwater vehicle, to control and distribute the desired generalized control force and torque based on the control distribution matrix, to distribute actual commands to each thruster and rudder, and to control the underwater vehicle during the diving and hovering phases based on the actual commands.

[0366] The third embodiment of the present invention also provides an electronic device, the electronic device comprising:

[0367] At least one processor; and,

[0368] The memory is communicatively connected to the at least one processor; wherein,

[0369] The memory stores instructions that can be executed by the at least one processor to enable the at least one processor to perform the underwater vehicle diving and hovering method of any of the foregoing embodiments.

[0370] The fourth embodiment of the present invention also provides a non-transitory computer-readable storage medium storing computer instructions for causing the computer to execute the underwater vehicle diving and hovering method described in any of the foregoing embodiments.

[0371] The fifth embodiment of the present invention also provides a computer program product, which includes a computing program stored on a non-transitory computer-readable storage medium. The computer program includes program instructions that, when executed by a computer, cause the computer to perform the underwater vehicle diving and hovering method of any of the foregoing embodiments.

[0372] Figure 2 The illustration shows a method or device 1000 implementing an embodiment of the present invention. In some embodiments, more or fewer devices may be included than illustrated. In some embodiments, it may be implemented using a single or multiple devices. In some embodiments, it may be implemented using cloud-based or distributed devices.

[0373] like Figure 2 As shown, device 1000 includes a processor 1001 for performing various appropriate operations and processes based on programs and / or data stored in read-only memory (ROM) 1002 or programs and / or data loaded from storage portion 1008 into random access memory (RAM) 1003. Processor 1001 may be a multi-core processor or may contain multiple processors. In some embodiments, processor 1001 may include a general-purpose main processor and one or more special coprocessors, such as a central processing unit (CPU), graphics processing unit (GPU), neural network processor (NPU), digital signal processor (DSP), etc. Various programs and data required for the operation of device 1000 are also stored in RAM 1003. Processor 1001, ROM 1002, and RAM 1003 are interconnected via bus 1004. Input / output (I / O) interface 1005 is also connected to bus 1004.

[0374] The processor and memory described above are used together to execute programs stored in the memory. When the program is executed by a computer, it can implement the methods, steps, or functions described in the above embodiments.

[0375] The following components are connected to I / O interface 1005: an input section 1006 including a keyboard, mouse, touchscreen, etc.; an output section 1007 including a cathode ray tube (CRT), liquid crystal display (LCD), etc., and speakers, etc.; a storage section 1008 including a hard disk, etc.; and a communication section 1009 including a network interface card such as a LAN card, modem, etc. The communication section 1009 performs communication processing via a network such as the Internet. A drive 1010 is also connected to I / O interface 1005 as needed. A removable medium 1011, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed on drive 1010 as needed so that computer programs read from it can be installed into storage section 1008 as needed. Figure 2 The diagram only shows a portion of the components and does not imply that the device 1000 only includes... Figure 2 The components shown.

[0376] The systems, devices, modules, or units described in the above embodiments can be implemented by a computer or its associated components. The computer may be, for example, a mobile terminal, smartphone, personal computer, laptop computer, in-vehicle human-machine interface device, personal digital assistant, media player, navigation device, game console, tablet computer, wearable device, smart TV, Internet of Things system, smart home, industrial computer, server, or a combination thereof.

[0377] Although not shown, in this embodiment of the invention, a computer-readable storage medium is provided having a computer program / instruction stored thereon, which, when executed by a processor, implements the method for underwater vehicle diving and hovering as described in the embodiment.

[0378] Storage media in embodiments of the present invention include articles that are permanent and non-permanent, removable and non-removable, capable of storing information by any method or technology. Examples of storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transfer medium that can be used to store information accessible by a computing device.

[0379] Although not shown, embodiments of the present invention also provide a computer program product, including: a computer program / instructions that, when executed by a processor, implement the method for underwater vehicle diving and hovering as described in the embodiments.

[0380] The methods, programs, systems, apparatuses, etc., in embodiments of the present invention can be executed or implemented in one or more networked computers, or practiced in a distributed computing environment. In the embodiments of this specification, in these distributed computing environments, tasks can be performed by remote processing devices connected via a communication network.

Claims

1. A method for underwater vehicles to dive and hover, characterized in that, Includes the following steps: Step S1: Establish a six-degree-of-freedom kinematic model and a six-degree-of-freedom dynamic model of the underwater vehicle in the Earth-fixed coordinate system and the Body-fixed coordinate system; Step S2: Based on the control requirements of the underwater vehicle under diving and hovering conditions, extract the longitudinal motion subsystem and the lateral motion subsystem from the six-degree-of-freedom kinematic model and the six-degree-of-freedom dynamic model. The longitudinal motion subsystem includes at least depth, vertical velocity, pitch angle and pitch angular velocity, and the lateral motion subsystem includes at least lateral displacement, lateral velocity, heading angle and heading angular velocity. Step S3: Obtain the actual state information of the underwater vehicle based on the longitudinal motion subsystem and the lateral motion subsystem, and set the desired state information based on the diving mission. Construct depth error, pitch error, lateral position error and heading error based on the actual state information and the desired state information, respectively. Construct a depth sliding surface based on the depth error, a pitch sliding surface based on the pitch error, a lateral sliding surface based on the lateral position error, and a heading sliding surface based on the heading error. The actual state information includes actual depth, actual pitch angle, actual lateral position and actual heading angle. The desired state information includes desired depth trajectory, desired pitch angle trajectory, desired lateral position and desired heading angle. Step S4: Using the longitudinal motion subsystem and the lateral motion subsystem as the controlled objects, and the depth sliding surface, pitch sliding surface, lateral sliding surface and heading sliding surface as feedback variables, set the sliding control laws for the depth, pitch, lateral and heading control channels respectively, and generate the expected generalized control force and torque for each channel based on the sliding control laws. Step S5: Based on the interaction between the actuators and the degrees of freedom of the underwater vehicle, establish the control allocation relationship. Based on the control allocation matrix, allocate the desired generalized control force and torque, assign actual commands to each thruster and rudder, and control the underwater vehicle during the diving and hovering phases based on the actual commands.

2. The method for underwater vehicle diving and hovering according to claim 1, characterized in that, The six-degree-of-freedom kinematic model include: ； In the formula, Let be the position and attitude vectors in the Earth-fixed coordinate system. ) represents the horizontal position coordinate in the Earth-fixed coordinate system, and z represents the depth in the Earth-fixed coordinate system. () is the attitude vector in the Earth-fixed coordinate system. This represents the matrix transpose operator, where This refers to the roll angle; The pitch angle; For heading angle; Let the linear velocity vector and angular velocity vector be in the body-fixed coordinate system. ) is the linear velocity vector in the body-fixed coordinate system, where The longitudinal velocity in the body-fixed coordinate system; The lateral velocity in the body-fixed coordinate system; The vertical velocity in the body-fixed coordinate system; ) is the angular velocity vector in the body-fixed coordinate system, where This refers to the roll angular velocity; It is the pitch angular velocity; Yaw angular velocity; This is the coordinate transformation matrix determined by the attitude angle; The six-degree-of-freedom dynamic model includes: ； In the formula, , The inertia matrix of a rigid body. For the additional mass matrix; Let be the linear and angular velocity vectors of the vehicle in its six degrees of freedom; Let be the linear and angular acceleration vectors of the vehicle in its six degrees of freedom; Coriolis and centrifugal matrices; Here is the damping matrix; This is the vector of restoring forces caused by gravity and buoyancy; To control the input vector; This represents the environmental disturbance vector.

3. The method for underwater vehicle diving and hovering according to claim 2, characterized in that, Longitudinal motion subsystem The state vector includes: ； In the formula, For longitudinal motion subsystem, The depth in the Earth-fixed coordinate system. The vertical velocity in the body-fixed coordinate system. The pitch angle, It is the pitch angular velocity; The longitudinal motion subsystem The longitudinal generalized control input is: ； In the formula, To generate the combined vertical thrust of the fore and aft vertical thrusters of the underwater vehicle. The pitch control moment is formed by the combined action of the front and rear vertical thrusters and the rudder of the underwater vehicle; Based on the six-degree-of-freedom dynamic model, the longitudinal motion subsystem Represented in state-space form : In the formula, The inherent dynamics of the longitudinal motion subsystem include the effects of mass and added mass, Coriolis force and centripetal force, fluid damping, gravity and buoyancy recovery, and the coupling between depth motion and pitch motion. The longitudinal control input matrix is ​​used to characterize the relationship between the combined vertical thrust and the combined pitch control moment on each longitudinal state variable; The longitudinal composite perturbation term includes at least the flow perturbation, model parameter perturbation, unmodeled dynamics, and coupled perturbations caused by neglected degrees of freedom, and is introduced by the longitudinal composite perturbation term. Lateral motion subsystem The state vector includes: In the formula, This represents the actual lateral position of the underwater vehicle in a ground-fixed coordinate system. Let be the lateral velocity in the body-fixed coordinate system. For heading angle, Angular velocity of heading; The lateral generalized control input of the lateral motion subsystem is: In the formula, The combined lateral thrust acting on the lateral degree of freedom is formed by the front lateral thruster and the rear lateral thruster. The combined yaw control torque acting on the yaw degree of freedom is formed by the differential thrust of the front and rear lateral thrusters and is adjusted in conjunction with the yaw torque generated by the rudder. Based on the six-degree-of-freedom dynamic model, the lateral motion subsystem Represented in state-space form : In the formula, For the intrinsic dynamics of the lateral motion subsystem, This is the lateral control input matrix. The lateral composite perturbation term includes at least lateral flow perturbation, model parameter perturbation, unmodeled dynamics, and coupled perturbation of longitudinal motion on lateral motion.

4. The method for underwater vehicle diving and hovering according to claim 3, characterized in that, Constructing a depth sliding surface based on depth error and its derivative. Deep sliding surface include: ； In the formula, For depth tracking error, , For actual depth, For the desired depth; For depth tracking error The derivative; For the parameters of the depth sliding surface, ; Pitch sliding surface constructed based on pitch error and its derivative. Pitch sliding surface include: ； In the formula, For pitch angle tracking error, , This is the actual pitch angle. The desired pitch angle; For pitch angle tracking error The derivative; For pitch sliding surface parameters, ; Constructing the transverse sliding surface based on the transverse position error and its derivative. Horizontal sliding surface include: ； In the formula, This is the lateral position error. , This refers to the actual horizontal position. The desired lateral position; For the transverse sliding surface parameters, ; Constructing the heading sliding surface based on the derivatives of heading error and lateral position error yaw sliding surface include: ； In the formula, This is the lateral position error. , This is the actual heading angle. The desired heading angle; For the heading sliding surface parameters, .

5. The method for underwater vehicle diving and hovering according to claim 4, characterized in that, Sliding mode control law include: ； In the formula, For sliding mode control law, For equivalent control items, To switch control items, , To switch the gain matrix, , For corresponding sliding surfaces, including depth sliding surfaces Pitch sliding surface Horizontal sliding surface and yaw sliding surface ; Boundary layer thickness, ; It is a saturation function.

6. The method for underwater vehicle diving and hovering according to claim 5, characterized in that, The sliding mode control law for each control channel includes ； In the formula, For the first The expected generalized control quantity for each control channel, For equivalent control items, To switch control items, To control the channel; Among them, the equivalent control item ; In the formula, For the first Control gain function for each control channel; The second derivative of the desired state; This represents the state vector of the corresponding motion subsystem; This is the desired state; For nominal dynamics; These are the parameters of the sliding surface; For tracking error; The switching control item ; In the formula, To switch gain, For linearly approaching gain, Boundary layer thickness; It is a saturation function. ; In the formula, It is a saturation function. For the first Sliding mode variables for each control channel To correspond to the boundary layer thickness, It is a symbolic function; The difference between the first and second derivatives of the desired depth, desired pitch angle, desired lateral position, and desired heading angle with respect to time in each channel is used as the state deviation. The sliding mode control law generates a compensating desired vertical generalized control force in real time based on the state deviation and external disturbances. Desired pitch generalized control torque Expected lateral generalized control and expected generalized control over the course It is used to maintain the depth, pitch, lateral position and heading of an underwater vehicle; The desired vertical generalized control force of the depth control channel is: ； In the formula, For the desired vertical control force, The control gain function for the depth control channel. This is the state vector of the longitudinal motion subsystem. For the desired depth, The second derivative of the desired depth, For the nominal dynamics term of the depth channel, For the parameters of the depth sliding surface, For depth tracking error, To switch gain, Boundary layer thickness, For linearly approaching gain, For depth sliding mode variables, It is a saturation function; The desired pitch generalized control torque of the pitch control channel is: ； In the formula, To achieve the desired pitch control torque, The control gain function for the pitch control channel. This is the state vector of the longitudinal motion subsystem. For the desired pitch angle, Let the second derivative be the desired pitch angle. For the nominal dynamics of the pitch channel, For pitch sliding surface parameters, For pitch angle tracking error, To switch gain, Boundary layer thickness, For linearly approaching gain, For pitch sliding mode variables, It is a saturation function; The desired lateral generalized control force of the lateral control channel is: ； In the formula, To achieve the desired lateral control, This is the control gain function for the lateral control channel. This is the state vector of the lateral motion subsystem. For the desired lateral position, Let the second derivative be the desired lateral position. For the nominal dynamics term of the transverse channel, For the transverse sliding surface parameters, For lateral position tracking error, To switch gain, Boundary layer thickness, For linearly approaching gain, For lateral sliding mode variables, It is a saturation function; The desired generalized heading control torque of the heading control channel is: In the formula, For the desired heading control torque, The control gain function for the heading control channel. This is the state vector of the lateral motion subsystem. For the desired heading angle, Let the second derivative of the desired heading angle be... For the nominal dynamics term of the heading channel, For the heading sliding surface parameters, For heading angle tracking error, To switch gain, Boundary layer thickness, For linearly approaching gain, For the heading sliding mode variable, It is a saturation function; The desired generalized control force and torque for each channel are generated based on the sliding mode control law. ,include: ； In the formula, For longitudinal expectation generalized control force; For the expected generalized control torque during roll; This represents the matrix transpose operation.

7. The method for underwater vehicle diving and hovering according to claim 6, characterized in that, The actuator includes at least a front vertical thruster, a rear vertical thruster, a front lateral thruster, a rear lateral thruster, a main thruster, and a rudder. Control allocation relationships include: ； In the formula, For actuator instruction vectors; To control the allocation matrix; Wherein, the actuator instruction vector include: ； In the formula, Main thruster thrust, and These are the thrust from the front vertical thruster and the thrust from the rear vertical thruster, respectively. and These are the thrust from the front lateral thruster and the thrust from the rear lateral thruster, respectively. This refers to the deflection angle of the rudder. The control allocation matrix include: ； in, The coefficient of influence of the main thruster on the longitudinal control force; The coefficient of influence of the forward vertical thruster on the vertical control force; The coefficient of influence of the rear vertical thruster on the vertical control force; This is the coefficient of influence of the forward lateral thruster on the lateral control force; This is the coefficient of influence of the rear lateral thruster on the lateral control force; The longitudinal lever arm of the forward vertical thruster relative to the center of gravity; The longitudinal lever arm of the rear vertical thruster relative to the center of gravity; The longitudinal lever arm of the forward lateral thruster relative to the center of gravity; The longitudinal lever arm of the rear lateral thruster relative to the center of gravity; , , , , and All are hydrodynamic coefficients of the rudder deflection on the corresponding six degrees of freedom; Based on the aforementioned control allocation relationship, the desired vertical generalized control force is obtained. Desired pitch generalized control torque Expected lateral generalized control and expected generalized control over the course At least the following conditions must be met: ； ； ； ； The initial actuator instruction is determined using the weighted generalized inverse method: ； In the formula, This is the initial instruction vector without considering actuator constraints. To control the weighted generalized inverse of the allocation matrix, The desired generalized control force vector; in: ； In the formula, It is a weighted generalized inverse matrix; Use a cost-weight matrix for the implementing agency; To control the allocation matrix; This represents the matrix transpose operation; The regularization coefficient is . ; It is the identity matrix; Command to the initial actuator By applying amplitude and rate of change constraints, the actual issued instructions are obtained. For the first A single actuator, wherein the amplitude constraint is expressed as: ； In the formula, For the first Constrained instructions from each executing agency; For the first The minimum number of instructions allowed by an executing agency; For the first The maximum number of instructions allowed by each executing agency; Index for the executing agency; The rate of change constraint is expressed as: ； In the formula, For the first The smallest instruction of an executing agency; For the first The maximum instruction of an executive agency; Maximum instruction change rate; To control the cycle; If the actual instruction is issued When some actuators reach their upper or lower output limits, calculate the control allocation residual. : ； In the formula, The desired generalized control force vector; To control the allocation matrix; This refers to the actuator command vector after applying amplitude and rate of change constraints. The control allocation residual The distribution among unsaturated actuators is made so that the actual generalized control output is... Approximate to the desired generalized control force vector .

8. A system for underwater vehicle diving and hovering, characterized in that, The method for underwater vehicle diving and hovering according to any one of claims 1-7 includes: The initialization unit is configured to establish a six-degree-of-freedom kinematic model and a six-degree-of-freedom dynamic model of the underwater vehicle in both the geo-fixed and body-fixed coordinate systems. The extraction unit is configured to extract a longitudinal motion subsystem and a lateral motion subsystem from a six-degree-of-freedom kinematic model and a six-degree-of-freedom dynamic model according to the control requirements of the underwater vehicle in the diving and hovering conditions. The longitudinal motion subsystem includes at least depth, vertical velocity, pitch angle and pitch rate, and the lateral motion subsystem includes at least lateral displacement, lateral velocity, heading angle and heading rate. The error unit is configured to acquire the actual state information of the underwater vehicle based on the longitudinal motion subsystem and the lateral motion subsystem, and set the desired state information based on the diving mission. Based on the actual state information and the desired state information, it constructs depth error, pitch error, lateral position error and heading error respectively. It constructs a depth sliding surface based on the depth error, a pitch sliding surface based on the pitch error, a lateral sliding surface based on the lateral position error, and a heading sliding surface based on the heading error. The actual state information includes actual depth, actual pitch angle, actual lateral position and actual heading angle. The desired state information includes desired depth trajectory, desired pitch angle trajectory, desired lateral position and desired heading angle. The control law unit is configured to take the longitudinal motion subsystem and the lateral motion subsystem as the controlled objects, and the depth sliding surface, pitch sliding surface, lateral sliding surface and yaw sliding surface as feedback variables, respectively set the sliding control laws for the depth, pitch, lateral and yaw control channels, and generate the expected generalized control force and torque for each channel based on the sliding control laws. The distribution unit is configured to establish a control distribution relationship based on the interaction between the actuators and the degrees of freedom of the underwater vehicle, to control and distribute the desired generalized control force and torque based on the control distribution matrix, to distribute actual commands to each thruster and rudder, and to control the underwater vehicle during the diving and hovering phases based on the actual commands.

9. An electronic device, characterized in that, The electronic device includes: At least one processor; and, The memory is communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor to enable the at least one processor to perform the method of underwater vehicle diving and hovering as described in any one of claims 1 to 7.

10. A non-transitory computer-readable storage medium, characterized in that, The non-transitory computer-readable storage medium stores computer instructions for causing the computer to perform the method of diving and hovering of the underwater vehicle as described in any one of claims 1 to 7.

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