CN105955268B - A kind of UUV moving-target sliding mode tracking control methods considering Local obstacle avoidance - Google Patents

Abstract

The present invention is to provide a kind of UUV moving-target sliding mode tracking control methods considering Local obstacle avoidance.Real-time detection UUV, moving target and obstacle position information；Obtain moving target k moment state estimations；Establish the relative motion model of UUV and moving target and barrier；The size for being evaded radius of safety based on target following radius and barrier is independently switched according to the relative position of UUV and moving target and barrier between tracking strategy and collision prevention strategy；According to command speed and course and the UUV speed of a ship or plane and turn bow angular velocity measurement feedback, obtains tracing control deviation, resolve to obtain k moment UUV propeller thrust based on horizontal plane non-singular terminal sliding mode controller and rudder turns bow torque；Cycle executes above-mentioned steps, realizes the tracing control at moving target lower a moment.Sector planning strategy in complex environment is combined by the present invention with UUV kinetic models, ensures the tracking accuracy to moving target under the premise of UUV nevigation safeties.

Description

A sliding mode tracking control method for UUV moving targets considering local collision avoidance

technical field

The invention relates to a target tracking method for an underwater unmanned vehicle, in particular to a moving target tracking method for an underwater unmanned vehicle.

Background technique

With the increase of UUV mission tasks and application fields, the ability requirements for UUV target tracking have also been greatly improved. It is required not only to identify stationary targets (such as rescue positioning to reach the crash point as soon as possible, mineral mining, pipeline positioning and maintenance), but also to track Maneuvering targets, making adaptive adjustments by predicting target state changes to avoid losing tracked objects.

At present, the research on moving target tracking is mainly concentrated in aerospace and other fields, mainly referring to target state estimation based on Kalman and particle filter; Induction method; artificial potential field, fuzzy collision avoidance method and other autonomous obstacle avoidance methods. The research on the UUV underwater environment is not yet mature enough, and there are few considerations for the obstacles that may occur during the execution of the established target trajectory tracking in the dynamic environment. Even if there is real-time motion planning, it is rarely combined with the UUV dynamic model and maneuverability This is achieved through motion control. Therefore, introducing the above factors into the UUV target tracking control to truly reflect its dynamic tracking and obstacle avoidance capabilities is of great significance for the safe and reliable execution of various tasks.

Contents of the invention

The purpose of the present invention is to provide a UUV moving target sliding mode tracking control method that can realize UUV tracking of moving targets while avoiding obstacles on its route, is stable, fast, and robust and considers local collision avoidance.

The purpose of the present invention is achieved like this:

Step 1: UUV detects UUV, moving target and obstacle position information in real time through navigation attitude sensor, position measurement system and forward-looking sonar;

Step 2: Establish the kinematics model of the moving target and the obstacle, and obtain the state estimation of the moving target at time k based on the insensitive Kalman filter;

Step 3: Establish the relative motion model of the UUV, the moving target, and the obstacle for calculating the tracking distance and line-of-sight angle at time k;

Step 4: Based on the size of the target tracking radius D ₁ and the obstacle avoidance safety radius D ₂ , according to the relative position of the UUV, the moving target and the obstacle, switch between the tracking strategy and the collision avoidance strategy autonomously, change the UUV control line of sight, and plan UUVk command speed and heading at all times;

Step 5: According to the command speed and heading obtained in step 4, and the UUV speed and bow angular velocity measurement feedback, the tracking control deviation is obtained, and the thrust of the UUV propeller and the rudder turning bow at time k are obtained based on the non-singular terminal sliding mode controller on the horizontal plane. torque;

Step 6: Perform steps 1 to 5 cyclically to realize the tracking control of the moving target at the next moment until the end of the task.

The present invention may also include:

1. The guidance method of autonomous switching between the tracking strategy and the collision avoidance strategy is specifically expressed as: during the global tracking process, if ρ _{oiv,k ≤} D ₂ +(R _io +R _v ), the collision avoidance guidance is activated Rhythm Switch the line of sight to obstacle avoidance, and execute the target tracking and guidance formula once the UUV is confirmed to move to a safe area Immediately resume the tracking process,

Where: ρ _oiv,k is the distance between UUV and the i-th obstacle at time k, UUV is simplified to radius R _v , R _io is the radius of the i-th obstacle, u _vRef,k is the UUV guidance speed at time k , r _vRef,k is the UUV guidance turning angle velocity at time k, for the maximum speed, is the minimum speed, ψv _,k is the course angle of the UUV at time k, is the UUV maximum bow angle velocity, n ₀ is the tracking speed gain, n ₁ is the tracking bow control gain, n ₂ is the collision avoidance speed gain, n ₃ is the collision avoidance bow control gain, _ρvg,k is the UUV and The distance between the targets, φ _vg,k is the sight angle between the UUV and the target at time k, that is, the angle between the line of sight vector and the Eξ axis of the inertial coordinate system, φ _oiv,k is the distance between the UUV and the i-th obstacle at time k The line of sight angle, D ₁ is the target tracking radius, D ₂ is the obstacle avoidance safety radius, is a saturation function and takes the minimum value of line of sight control and saturation angular velocity, Φ(α) converts the rotation angle to the interval [-π,π].

2. The thrust of the UUV propeller and the turning moment of the rudder described in step five are specifically expressed as:

Among them: UUV thruster thrust τ _u, k at time k, rudder turning bow moment τ _r, k at time k, UUV actual speed u _v, k at time k, UUV guidance speed u _vRef, k at time k, actual UUV rotation speed at time k Bow angular velocity r _v,k , UUV guidance turning bow angular velocity r _vRef,k , UUV lateral motion velocity v _{v,k at time k} ; non-singular terminal speed control sliding mode surface s ₁ and turning bow control sliding mode surface s ₂ , sliding mode surface adjustable parameters β ₁ >0, β ₂ >0, p ₁ , q ₁ , p ₂ , q ₂ are positive odd numbers and Speed tracking control deviation u _e,k =u _vRef,k -u _v,k , heading angular velocity control deviation r _e,k =r _ref,k -r _v,k ; d ₁₁ ＝X _u +X _|u|u |u|, d ₂₂ ＝Y _v +Y _|v|v |v|, d ₃₃ ＝Z _w +Z _|w|w |w| is a dynamic model parameter; "^" indicates the estimated value of the system model parameters, and i = 1, 2, 3, 5, 6, indicating the perturbation of the model parameters, c ₁ sat(s ₁ /φ ₁ ), c ₂ sat(s ₂ /φ ₂ ) are the discontinuous switching items of the sliding mode controller , c ₁ , φ ₁ , c ₂ , φ ₂ are adjustable parameters for changing chattering and perturbation capabilities.

The control target of the guidance strategy of the present invention is: considering the UUV saturation constraints, the problem of target tracking and local obstacle avoidance in a two-dimensional dynamic environment. ① For position tracking, if Then there exists D ₁ >0 such that for Have ②For the obstacle avoidance problem, if ρ _oiv (t ₀ )＞D ₂ , then there exists D ₂ >0, so that for ρ _oiv (t)>(R _io +R _v ) holds.

Among them, q=[xy ψ] ^T represents the position and heading angle in the inertial coordinate system, U=[ur] ^T represents the kinematics control vector composed of the speed of the ship and the angular velocity of the bow, and q _v,k =[x _v,k y _v,k ψ _v,k ] ^T , U _v,k =[u _v,k r _v,k ] ^T represents the UUV state at time k, q _g,k =[x _g,k y _g,k ψ _{g, k} ] ^T , U _g,k ＝[u _g,k r _g,k ] ^T represents the target state at time k, q _io,k ＝[x _io, ky _io,k ψ _io,k ] ^T , U _{io ,k} =[u _io,k r _io,k ] ^T represents the state of the i-th obstacle at time k. Simplify the UUV into a circle with radius R _v and center position (x _{v, k} , y _{v, k} ) _{, which} is similar to the simplified representation of the target with radius R _g and the obstacle with radius R _io . ρ _vg,k is the distance between the UUV and the target at time k, φ _vg,k is the line-of-sight angle between the UUV and the target at time k (the angle between the line-of-sight vector and the Eξ axis of the inertial coordinate system); ρ _oiv,k is k The distance between the UUV and the i-th obstacle at time, φ _oiv,k is the line-of-sight angle between the UUV and the i-th obstacle at time k; D ₁ is the target tracking radius, and D ₂ is the obstacle avoidance safety radius.

For the saturation constraint on UUV speed and course, set the maximum speed as Maximum steering change rate In addition, in order to ensure that the UUV is lurking underwater, its speed cannot be decelerated to zero (it will surface), and the minimum speed is set as Then there are: The guidance strategy formulated is as follows:

(1) The target tracking and guidance law is:

Among them, n ₀ is the constant speed gain, in order to ensure the smoothness of tracking, the UUV will track at a speed proportional to the distance when it is far behind the target; n ₁ is the control gain of turning the bow, and Φ(α) limits the turning angle to interval[-π,π); is the saturation function, taking the minimum value of line-of-sight control and saturation angular velocity.

(2) The guidance law for collision avoidance is:

Among them, 0<n ₂ ≤1 speed control gain, n ₃ is designed as a normal constant bow control gain.

(3) Line of sight switching strategy: During the global tracking process, if ρ _{oiv,k ≤} D ₂ +(R _io +R _v ) occurs, the collision avoidance guidance law is activated to switch the line of sight to obstacle avoidance, Once it is confirmed that the UUV has moved to a safe area, the target tracking and guidance law will be executed, and the tracking process will be resumed immediately.

The present invention designs the following non-singular terminal sliding mode speed controller and bow controller:

The thrust control law of the UUV thruster is:

The UUV rudder steering moment control law is:

in, d ₁₁ ＝X _u +X _|u|u |u|, d ₂₂ ＝Y _v +Y _|v|v |v|, d ₃₃ ＝Z _w +Z _|w|w |w| is a dynamic model parameter; "^" indicates the estimated value of the system model parameters, and i = 1, 2, 3, 5, 6, indicating the perturbation of the model parameters, c ₁ sat(s ₁ /φ ₁ ), c ₂ sat(s ₂ /φ ₂ ) are the discontinuous switching items of the sliding mode controller , by adjusting the parameters c ₁ , φ ₁ , c ₂ , φ ₂ can enhance the robustness of the controller and improve the chattering phenomenon of the sliding mode.

The speed tracking error of UUV is u _e,k ＝u _vRef,k -u _v,k , and the tracking error of turning bow angle velocity is r _e,k ＝r _ref,k -r _v,k , the designed non-singular Terminal sliding surface They are:

Among them, β ₁ >0, β ₂ >0, p ₁ , q ₁ , p ₂ , q ₂ are positive odd numbers and

The present invention provides a guidance strategy capable of realizing UUV tracking a moving target while avoiding obstacles on its route, and provides a specific implementation method in combination with the UUV dynamic model and motion control capability. The beneficial effects of the present invention are:

(1) Using the distance between the UUV and the target and obstacles as the dynamic programming criterion, the analysis of the dynamic environment target tracking and local obstacle avoidance problems is simplified, and the simple and effective switching strategy formulated by considering the motion control constraints of the UUV realizes the UUV Real-time smooth motion planning with safety and tracking accuracy requirements.

(2) A non-singular terminal sliding mode controller is designed, which can eliminate the possible singularity of the system during the control process, realize stable control of the command within a limited time, and is very suitable for underwater nonlinearity, where there are environmental disturbances and model parameters Perturbed complex working conditions. An effective tracking process considering the UUV dynamics model is realized, which is stable, fast and robust.

Description of drawings

Fig. 1 is the overall block diagram of the present invention;

Fig. 2 is a schematic diagram of UUV target tracking and passive obstacle avoidance dual target control problem in the plane;

Fig. 3 is a schematic diagram of UUV target tracking guidance;

Figure 4 is a schematic diagram of UUV obstacle collision avoidance guidance;

Figure 5 is the trajectory of the UUV tracking moving target simulation case;

Figures 6a to 6d are the control parameter diagrams of the UUV tracking moving target simulation case;

Figure 7 is the trajectory of a UUV tracking a moving target while avoiding a dynamic obstacle simulation case;

Figures 8a to 8d are control parameter diagrams of a simulation case of UUV tracking a moving target while avoiding dynamic obstacles;

Fig. 9 is a flowchart of the present invention.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing:

When UUV performs tasks such as recovery and docking, it needs to follow and track specific targets. For complex underwater environments, random obstacles (ships, plankton, underwater garbage, etc.) will inevitably appear on the track of target movement routes. The invention provides a simple and effective UUV dynamic environment tracking control method.

Fig. 1 is an overall working block diagram of the present invention, which is mainly divided into four parts: UUV model and detection system, target state estimation, dynamic programming module and non-singular terminal sliding mode controller. The positions of targets and obstacles are obtained by the UUV sonar detection system, The UUV real-time status information is determined by its integrated navigation system, and the specific steps of the present invention are described in conjunction with FIG. 9 .

Step 1: UUV detects UUV, moving target and obstacle position information in real time through navigation attitude sensor, position measurement system, forward-looking sonar, etc.

Step 2: Establish the kinematics model according to the movement law of the target and the obstacle, and obtain the state estimation at time k by the Unsensitive Kalman (UKF) filter algorithm based on the position of the track point;

Let the target dynamic model be X _k ＝FX _k-1 +GW _k , the state vector F is the system transition matrix, G is the system noise transformation matrix, the system state noise W _k =[w _x,k ,w _y,k ] ^T is zero-mean Gaussian noise, and the covariance is Q _k . The observation model is Z _k ＝h(X _k )+V _k , where h is the observation function, V _k is the measurement noise sequence obeying the Gaussian distribution, the covariance is R _k , and there is

cov[W _k ]=Q _k , cov[V _k ]=R _k

The simplified process of the UKF algorithm is:

1. Given the initial value of the system (the estimated value of the initial state mean value Initial state variance estimate P ₀ )

2. Calculate the Sigma sampling point χ _i and its weight λ _i , and approximate the distribution function of the system state with the smallest sample set

Among them, n is the dimension of the state vector, and κ is the scale parameter, which is 2 in this design.

3. Prediction/time update, perform nonlinear transformation and weighting processing on the Sigma sampling points, and obtain the one-step prediction value of the state vector mean, state vector variance and output vector P _k|k-1 、

The transformed state variable is used for filter estimation to reduce the estimation error, and at the same time, the linearization error is avoided because the algorithm uses nonlinear dynamic equation or measurement equation.

4. Calibration/measurement update

Among them, Y _k is the observed value at time k, P _k is the variance of output vector and state vector at time k respectively, is the covariance of the two, M _k is the UKF correction gain, That is, the filtered estimated value of the state at time k.

Step 3: According to the state information filtered in step 2, based on the relative motion model of UUV, moving target and obstacle, calculate the tracking distance and line-of-sight angle at time k, as shown in Figure 2, UUV target tracking and passive avoidance in the plane Obstacle dual-objective control problem;

When formulating the guidance strategy, it is considered that the UUV lateral velocity is a small coupling quantity, which has little influence on the trajectory. When designing, the kinematics model is simplified to the form of formula (5), and it is assumed that the target and the obstacle satisfy the same motion law:

Where q=[xy ψ] ^T represents the position and heading angle in the inertial coordinate system, U=[ur] ^T represents the kinematics control vector composed of the speed and the angular velocity of the bow. At time k, UUV is represented by vector q _v,k =[x _v, ky _v,k ψ _v,k ] ^T , U _v,k =[u _v,k r _v,k ] ^T , and the target is represented by q _g,k ＝[x _g,k y _g,k ψ _g,k ] ^T , U _g,k ＝[u _g,k r _g,k ] ^T , and the i-th obstacle is represented by q _io,k = [x _io, ky _io,k ψ _io,k ] ^T , U _io,k ＝[u _io,k r _io,k ] ^T to represent; in the schematic diagram UUV is simplified to radius R _v , and the center position is (x _v,k ,y _v,k ), similar to the simplified representation of the target with radius R _g and the obstacle with radius R _io .

Bring in the relative motion model of UUV and target:

Among them, ρ _vg,k is the distance between the UUV and the target at time k, and φ _vg,k is the line-of-sight angle between the UUV and the target at time k (the angle between the line-of-sight vector and the Eξ axis of the inertial coordinate system).

Formula (6) takes the differential form, and the simultaneous formula (5) is derived to obtain the form of tracking error between UUV and target:

Similarly, the relative motion model of the UUV and the i-th obstacle is:

Among them, ρ _oiv,k is the distance between the UUV and the i-th obstacle at time k, and φ _oiv,k is the line-of-sight angle between the UUV and the i-th obstacle at time k.

Step 4: Based on the relative position of the UUV, the target and the obstacle at time k calculated in step 3, combined with the requirements of the target tracking radius D ₁ and the obstacle avoidance safety radius D ₂ , formulate an autonomous switching strategy for global tracking and local collision avoidance, Change the UUV control line of sight, plan its command speed u _vRef,k and command heading r _{vRef,k at time k} ;

(1) Target tracking and guidance law: Under the limitation of the maximum turning angle speed, the UUV is designed to control the course of the UUV to turn to the direction of the tracking line of sight as soon as possible, and when the UUV is within the target approach circle, it will keep monitoring at the target speed, and when the target maneuvers to escape to the tracking When the UUV is outside the circle, it uses the maximum speed to track, as shown in Figure 3. It is beneficial to reduce the amount of control to choose the method of constant linear speed as much as possible, and increase the flexibility of speed control by turning the bow control, which can be specifically expressed as:

Among them, UUV has a maximum speed Maximum steering change rate The saturation constraint of , and to ensure that the UUV is lurking underwater, the minimum speed is set as which is n ₀ is a constant speed gain. In order to ensure the smoothness of tracking, the UUV will track at a speed proportional to the distance when it is far behind the target; is the saturation function, taking the minimum value of line-of-sight control and saturation angular velocity, the function is expressed as:

n ₁ is the steering bow control gain, Φ(α) limits the steering angle to the interval [-π,π), defined as:

( ₂ ) Collision avoidance guidance law: when the target enters the obstacle circle with a radius of D2, the design controls the UUV to turn away from the obstacle’s line of sight direction as soon as possible at the maximum linear velocity under the limit of the maximum turning angle velocity, as shown in The obstacle avoidance guidance strategy shown in Figure 4, the function is expressed as:

Among them, 0<n ₂ ≤1 speed control gain, n ₃ is designed as a normal constant bow control gain.

(3) Line of sight switching strategy: Based on the guidance of the above two situations, it can be proved that there is (n ₀ ,n ₁ ,D ₁ ) so that the tracking error of the UUV to the target converges to D ₁ consistently, and there is (n ₂ ,n ₃ , D ₂ ) such that at the initial moment Under certain conditions, the system can guarantee successful obstacle avoidance. The strategy to obtain target tracking and passive obstacle avoidance in a dynamic environment is: in the global tracking process, if ρ _{oiv,k ≤} D ₂ +(R _io +R _v ) occurs at the moment, the collision avoidance and guidance law is activated, and the line of sight Switch to obstacle avoidance, and immediately resume the tracking process once the UUV is confirmed to move to a safe area.

Step 5: After formulating the tracking strategy, it needs to be controlled in combination with the power mechanism. Therefore, according to the guidance command in step 4 and the UUV speed and bow angular velocity measurement feedback, the tracking control deviation is obtained. The design has a strong effect on parameter perturbation and environmental interference. Robust non-singular terminal sliding mode controller, the UUV thruster thrust τ _u,k and rudder turning bow moment τ _r,k at time k are obtained through calculation;

For the horizontal plane UUV dynamics model has the following simplified form:

Take the guidance law u _vRef,k and r _vRef,k obtained in step 4 as the expected motion control command at time k, and compare it with the actual speed and heading of the UUV to obtain the tracking control deviation u _e,k =u _vRef,k -u _{v ,k} ，r _e,k ＝r _ref,k -r _v,k , based on the principle of non-singular terminal sliding mode, design the velocity and bow control sliding mode surfaces respectively:

Among them, the adjustable parameters β ₁ >0, β ₂ >0, p ₁ , q ₁ , p ₂ , q ₂ are positive odd numbers and

The control law of UUV thrust and turning moment on the horizontal plane is derived as follows:

in, d ₁₁ ＝X _u +X _|u|u |u|, d ₂₂ ＝Y _v +Y _|v|v |v|, d ₃₃ ＝Z _w +Z _|w|w |w| is a dynamic model parameter; "^" indicates the estimated value of the system model parameters, and i = 1, 2, 3, 5, 6, indicating the perturbation of the model parameters, c ₁ sat(s ₁ /φ ₁ ), c ₂ sat(s ₂ /φ ₂ ) are the discontinuous switching items of the sliding mode controller .

Construct Lyapunov function Both are positive definite, respectively deriving can prove that

Negative determination, it can be seen that the UUV tracking control deviation can be stabilized to zero state in a limited time, that is, the actual speed and actual bow angle speed can track the guidance command in a limited time.

Step 6: At time k+1, jump to step 1 and execute steps 1 to 5 to obtain real-time tracking control τ _u,k+1 and τ _r,k+1 ; as the sampling proceeds, loop the above process until receiving Task end command.

Two example simulations of the present invention are given, and the trajectory and motion control parameter diagrams are shown in the accompanying drawings. Fig. 5, Fig. 6a to Fig. 6d show the maneuvering target tracking process, and the whole process is relatively stable; Fig. 7, Fig. 8a to Fig. 8d show that the tracking environment is unknown, and moving obstacles interfere with the route. Still fast and stable control.

Let the trajectory equation of the random moving obstacle be

UUV radius R _v =3m, moving obstacle radius R _o =5m, target approach circle radius D ₁ =10m, obstacle risk zone radius D ₂ =25m, data collection interval T _o =0.5s. It can be seen that the precision of the sliding mode controller is extremely high, the response to the control command is fast and the error is small, and the actual track of the UUV can basically coincide with the planned track. In the case of Figure 7, on the one hand, this simulation method can guarantee the tracking accuracy of the moving target, on the other hand, when ρ _ov (t)≤D ₂ +(R _o +R _v )=33m, the obstacle avoidance control is activated until ρ _ov ( t)>D ₂ +(R _o +R _v ), ρ _ov (min)=26.8024m>R _o +R _v =8m during the short-term obstacle avoidance period ensures the navigation safety of UUV all the time.

Claims (3)

1. A UUV moving target sliding mode tracking control method considering local collision avoidance is characterized by comprising the following steps:

the method comprises the following steps: the UUV detects the position information of the UUV, a moving target and an obstacle in real time through a navigation attitude sensor, a position measuring system and a forward-looking sonar;

step two: establishing a kinematic model of the moving target and the obstacle, and acquiring a k moment state estimation of the moving target based on insensitive Kalman filtering;

step three: establishing a relative motion model of the UUV, the moving target and the obstacle, and calculating a tracking distance and a line-of-sight angle at the moment k;

step four: based on target tracking radius D₁And obstacle avoidance safety radius D₂The method comprises the following steps of automatically switching between a tracking strategy and a collision avoidance strategy according to the relative positions of a UUV, a moving target and an obstacle, changing the UUV control sight line, and planning the instruction speed and the course of the UUV at the moment;

step five: measuring and feeding back according to the instruction speed and the course obtained in the fourth step, the UUV navigational speed and the heading turning angular speed to obtain tracking control deviation, and resolving to obtain UUV propeller thrust and rudder heading turning moment at the k moment based on a horizontal non-singular terminal sliding mode controller;

step six: and circularly executing the first step to the fifth step to realize the tracking control of the moving target at the next moment until the task is finished.

2. The method for controlling the sliding mode tracking of the UUV moving target considering the local collision avoidance according to claim 1, wherein the guidance mode for autonomous switching between the tracking strategy and the collision avoidance strategy is specifically expressed as: in the global tracking process, if p occurs_oiv,k≤D₂+(R_io+R_v) Then activate the collision avoidance guidance lawSwitching line of sight to obstacle avoidance aspect, executing target tracking guidance law once UUV movement to safe area is confirmedThe tracking procedure is resumed immediately and,

wherein: rho_oiv,kIs the distance between UUV and i-th obstacle at time k, R_ioFor the radius of the ith obstacle, UUV is simplified to radius R_v，u_vRef,kFor the UUV guidance speed at time k, r_vRef,kGuiding the angular speed of the bow to be turned for the UUV at the moment k,To maximum speed of flight、Is the minimum speed, psi_v,kIs the course angle of UUV at the time k,Is the maximum bow turning angular velocity n of UUV₀Gain, n, for tracking velocity₁Controlling gain, n, for tracking bow turn₂Gain n for collision avoidance speed₃Controlling gain, rho, for collision avoidance steering_vg,kIs the distance between UUV and target at time k, phi_vg,kIs the included angle phi between the sight line angle of UUV and target at the moment k, i.e. the sight line vector and the axis of an inertial coordinate system E ξ_oiv,kIs the line of sight angle D between UUV and i-th obstacle at time k₁Tracking radius, D, for the target₂For avoiding the safe radius of the obstacle,For the saturation function and taking the minimum of the line-of-sight control and the saturated angular velocity, phi (α) converts the rotation angle to the interval [ -pi, pi [ -pi [, ]]。

3. The UUV moving target sliding mode tracking control method considering local collision avoidance according to claim 1 or 2, wherein in the fifth step, the thrust of the UUV propeller and the rudder bow-turning moment are specifically expressed as follows:

wherein: UUV thruster thrust tau at moment k_u,kMoment tau of steering at time k_r,kUUV actual navigational speed u at moment k_v,kUUV guiding speed u at time k_vRef,kUUV actual bow turning angular velocity r at time k_v,kUUV guiding bow turning at moment kAngular velocity r_vRef,kUUV transverse movement speed v at moment k_v,k(ii) a Nonsingular terminal speed control sliding mode surface s₁And the control slip form surface s of the bow₂Parameter β adjustable by sliding mode surface₁＞0、β₂＞0，p₁、q₁、p₂、q₂Is positive odd andspeed tracking control deviation u_e,k＝u_vRef,k-u_v,kHeading angular velocity control deviation r_e,k＝r_ref,k-r_v,k； d₁₁＝X_u+X_|u|u|u|，d₂₂＝Y_v+Y_|v|v|v|，d₃₃＝Z_w+Z_|w|wThe | w | is a kinetic model parameter; "[ lambda ] denotes an estimated value of a system model parameter, andi is 1,2,3,5,6, and represents the amount of shooting of the model parameter, c₁sat(s₁/φ₁)、c₂sat(s₂/φ₂) Being discontinuous switching terms of sliding mode controllers, c₁、φ₁、c₂、φ₂To change the adjustable parameters of buffeting and perturbation ability.