UUV (Unmanned Underwater Vehicle) path tracking method based on self-adaption sliding-mode control

Abstract

The invention provides a UUV (Unmanned Underwater Vehicle) path tracking method based on self-adaption sliding-mode control. The method comprises the steps of 1, initializing; 2, obtaining a current state of a UUV; 3, establishing an underactuated UUV horizontal error equation to obtain the positional deviation xe, ye and a course deviation value psi e; 4, utilizing a sliding-mode control method to respectively design a speed sliding-mode control law, a position sliding-mode control law and a stem phase angle sliding-mode control law and enabling th ud to be zero, the xe to be zero and the psi e to be zero by controlling thrust Xprop, expected speed (shown in the following image) and torque Nprop; 5, updating a self-adaption law of handover gain and a self-adaption law of boundary layer thickness; 6, performing control input saturation compensation; 7, enabling k = k +1, returning to the step 2 and updating the control laws and the self-adaption laws for the next time to achieve the accurate control on the UUV horizontal path tracking. The UUV path tracking method can only depend on a controller which is designed according to a horizontal dynamical model to stabilize the system and is suitable for various underactuated UUVs.

Description

technical field

[0001] The present invention relates to a UUV path tracking method, in particular to a tracking control method for an underdriven UUV in a horizontal plane to a desired path. Background technique

[0002] The path tracking control of Unmanned Underwater Vehicle (UUV) is an important technical basis for realizing various uses of UUV. In-depth study of the problems existing in UUV path tracking is of great significance to UUV control theory and engineering applications.

[0003] At present, in the aspect of underactuated UUV path tracking control, one of the more mainstream ideas is to establish a kinematic error equation based on the Serret-Frenet coordinate system, and then combine the error equation, dynamic equation and various control methods to achieve control. Among them, common control algorithms include backstepping, model predictive control, sliding mode variable structure control, etc. The backstepping method has obvious advantages in stabilizing c...

Examples

specific Embodiment approach 1

[0035] Specific implementation mode one: combine Figure 4 , the UUV path tracking method based on adaptive sliding mode of the present invention, comprises the steps:

[0036] Step 1. Initialization:

[0037] is various adaptive parameters k of UUV i ,λ i (i=1,2,3) assign initial value, and determine its ideal speed u for the path following process d , define update times t=0;

[0038] Step 2. Obtain the current state of the UUV:

[0039] The current moment status is obtained through a series of sensors of the UUV itself: u, v are the longitudinal and lateral speeds (m / s), r are the yaw angular speeds (rad / s), and x, y are the UUV relative to the fixed coordinates position of the system (m), ψ is the yaw angle (rad), determine the longitudinal velocity error e u =u-u d ;

[0040] Step 3. Based on the Serret-Frenet coordinate system, establish the underactuated UUV horizontal plane error equation to obtain the position deviation x e ,y e and heading deviation ψ e ; ...

specific Embodiment approach 2

[0054] Embodiment 2: On the basis of Embodiment 1, based on the Serret-Frenet coordinate system described in step 3, the underactuated UUV horizontal plane error equation is established to obtain the position deviation x e ,y e and heading deviation ψ e The specific process is as follows:

[0055] For the movement of UUV in the horizontal plane, it is only necessary to establish a three-degree-of-freedom model, and the variables to be considered are: position x, y, heading angle ψ, longitudinal velocity u, lateral velocity v, and yaw angular velocity r. The kinematic equation of UUV horizontal plane can be obtained as:

[0056] x · = u c o s ψ - v s ...

specific Embodiment approach 3

[0089] Specific implementation mode three: on the basis of specific implementation mode one or two, utilize the sliding mode control method described in step 4 to design respectively the speed sliding mode control law, the position sliding mode control law and the bow angle sliding mode control law, by against thrust X prop , expected speed and torque N prop control so that u d →0,x e →0,ψ e →0 The specific process is as follows:

[0090] In order to design a controller designed for UUV path tracking, the present invention makes the following reasonable assumptions:

[0091] Assumption 1: The speed U of the UUV can be regarded as the longitudinal speed u of the UUV;

[0092] Hypothesis 2: Minimum speed u min and the maximum speed u max , so that u d ∈[u min , u max ],u max > u min >0;

[0093] On the basis of the above assumptions, the sliding mode control law of the UUV's speed tracking subsystem is firstly designed. For the first formula in (6), use

[009...

technical field

[0001] The present invention relates to a UUV path tracking method, in particular to a tracking control method for an underdriven UUV in a horizontal plane to a desired path. Background technique

[0002] The path tracking control of Unmanned Underwater Vehicle (UUV) is an important technical basis for realizing various uses of UUV. In-depth study of the problems existing in UUV path tracking is of great significance to UUV control theory and engineering applications.

[0003] At present, in the aspect of underactuated UUV path tracking control, one of the more mainstream ideas is to establish a kinematic error equation based on the Serret-Frenet coordinate system, and then combine the error equation, dynamic equation and various control methods to achieve control. Among them, common control algorithms include backstepping, model predictive control, sliding mode variable structure control, etc. The backstepping method has obvious advantages in stabilizing c...

Examples

specific Embodiment approach 1

[0035] Specific implementation mode one: combine Figure 4 , the UUV path tracking method based on adaptive sliding mode of the present invention, comprises the steps:

[0036] Step 1. Initialization:

[0037] is various adaptive parameters k of UUV i ,λ i (i=1,2,3) assign initial value, and determine its ideal speed u for the path following process d , define update times t=0;

[0038] Step 2. Obtain the current state of the UUV:

[0039] The current moment status is obtained through a series of sensors of the UUV itself: u, v are the longitudinal and lateral speeds (m / s), r are the yaw angular speeds (rad / s), and x, y are the UUV relative to the fixed coordinates position of the system (m), ψ is the yaw angle (rad), determine the longitudinal velocity error e u =u-u d ;

[0040] Step 3. Based on the Serret-Frenet coordinate system, establish the underactuated UUV horizontal plane error equation to obtain the position deviation x e ,y e and heading deviation ψ e ; ...

specific Embodiment approach 2

[0054] Embodiment 2: On the basis of Embodiment 1, based on the Serret-Frenet coordinate system described in step 3, the underactuated UUV horizontal plane error equation is established to obtain the position deviation x e ,y e and heading deviation ψ e The specific process is as follows:

[0055] For the movement of UUV in the horizontal plane, it is only necessary to establish a three-degree-of-freedom model, and the variables to be considered are: position x, y, heading angle ψ, longitudinal velocity u, lateral velocity v, and yaw angular velocity r. The kinematic equation of UUV horizontal plane can be obtained as:

[0056] x · = u c o s ψ - v s ...

specific Embodiment approach 3

[0089] Specific implementation mode three: on the basis of specific implementation mode one or two, utilize the sliding mode control method described in step 4 to design respectively the speed sliding mode control law, the position sliding mode control law and the bow angle sliding mode control law, by against thrust X prop , expected speed and torque N prop control so that u d →0,x e →0,ψ e →0 The specific process is as follows:

[0090] In order to design a controller designed for UUV path tracking, the present invention makes the following reasonable assumptions:

[0091] Assumption 1: The speed U of the UUV can be regarded as the longitudinal speed u of the UUV;

[0092] Hypothesis 2: Minimum speed u min and the maximum speed u max , so that u d ∈[u min , u max ],u max > u min >0;

[0093] On the basis of the above assumptions, the sliding mode control law of the UUV's speed tracking subsystem is firstly designed. For the first formula in (6), use

[009...

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