Method and system for hierarchical disturbance rejection depth tracking control of underactuated underwater vehicle

Patent metadata

Field	Value
Publication number	US-11809201-B1
Application number	US-202318324171-A
Country	US
Kind code	B1
Filing date	May 26, 2023
Priority date	Sep 9, 2022
Publication date	Nov 7, 2023
Grant date	Nov 7, 2023

Abstract

The disclosure provides a method and system for hierarchical disturbance rejection depth tracking control of an underactuated underwater vehicle, and the depth tracking of the underactuated underwater vehicle is divided into kinematic layer guidance and dynamic layer pitch tracking. Adaptive line of sight guidance is used in the kinematic layer to convert a depth error into a desired pitch angle and to estimate and compensate an angle of attack to reject disturbance introduced by an unmeasurable true angle of attack. Based on the above, in the dynamic layer, the active disturbance rejection sliding mode pitch tracking method is used to observe a composite disturbance including an unknown dynamic model and an environmental disturbance by using the active disturbance rejection framework. The model is compensated as a unified integral series type, a sliding mode control law is finally designed to resist an observation error, and a control elevator angle is calculated.

First claim

What is claimed is:

1. A method for hierarchical disturbance rejection depth tracking control of an underactuated underwater vehicle, comprising:
determining navigation information of the underwater vehicle, wherein the navigation information comprises a desired depth, a current depth, a current navigation speed, and a current pitch angle;
determining a depth tracking error according to the desired depth and the current depth and converting the depth tracking error into a desired pitch angle based on an adaptive line-of-sight guidance law, specifically comprises:
subtracting a current depth z from a desired depth z d to obtain the depth tracking error e z ;
converting the depth tracking error e z into a desired pitch angle θ d based on the adaptive line-of-sight guidance law specifically through the following formula:

θ
d

=

tan

-
1

(

e
z

Δ

+

α
ˆ

)

,

where Δ is the forward-looking distance, and {circumflex over (α)} is the adaptive parameter,
wherein the adaptive line-of-sight guidance law comprises an adaptive parameter, so as to estimate a real angle of attack of the underwater vehicle and reduce a motion disturbance introduced by ignoring the angle of attack, and the adaptive parameter is determined according to the current navigation speed and the depth tracking error;
determining an active disturbance rejection sliding mode pitch tracking control law comprising an extended state observer and a sliding mode feedback control law; wherein the extended state observer is configured to observe a composite disturbance of the underwater vehicle, specifically comprises: a pitch motion model of the underwater vehicle is:
{umlaut over (θ)}= f (θ,{dot over (θ)}, U,I yy . . . )+ b 0 δ+d θ ,

where {umlaut over (θ)} represents the pitch angular acceleration rate, f(θ, {dot over (θ)}, U, I yy . . . ) represents the acceleration rate corresponding to the moment caused by the internal structure of the vehicle, θ represents the vehicle pitch angle, {dot over (θ)} represents the vehicle pitch angular velocity, U represents the navigation speed, I yy represents the moment of inertia of the vehicle, d θ is the external environment disturbance, b 0 is the elevator effect coefficient, and δ is the final elevator angle,
considering f(θ, {dot over (θ)}, U, I yy . . . )+d θ as a composite disturbance and using the following extended state observer to iteratively calculate the composite disturbance:

{

e
=

z
1

[
t
]

-
θ

z
1

[

t
+
1

]

=

z
1

[
t
]

+

h
⁡
(

z
2

[

t
+
1

]

-

l
1

⁢
e

)

z
2

[

t
+
1

]

=

z
2

[
t
]

+

h
⁡
(

z
3

[

t
+
1

]

-

l
2

⁢
e

+

b
0

⁢
δ

Assignees

• Univ Huazhong Science Tech

Inventors

• Xiang Xianbo
• Liu Chuan
• Yang Shaolong
• Xiang Gong
• Zhang Qin

Classifications

• G05D1/048 Primary

  specially adapted for water vehicles · CPC title

• B63G8/24 Primary

  Automatic depth adjustment; Safety equipment for increasing buoyancy, e.g. detachable ballast, floating bodies · CPC title

• B63G8/18

  by hydrofoils · CPC title

• B63G2008/004

  autonomously operating · CPC title

• G05D1/0692 Primary

  specially adapted for under-water vehicles · CPC title