CN-121979270-A - Under-actuated ship track tracking fixed time fault-tolerant control method under output constraint

CN121979270ACN 121979270 ACN121979270 ACN 121979270ACN-121979270-A

Abstract

The invention discloses an underactuated ship track tracking fixed time fault-tolerant control method under output constraint, which comprises the steps of constructing a fixed time sliding mode fault observer; the method comprises the steps of establishing a virtual control law of preset time performance according to an under-actuated ship mathematical identification model based on a fixed time preset performance function, defining a transverse speed error and a longitudinal speed error according to the virtual control law by combining a fixed time sliding mode fault observer to establish a saturation compensator for compensating the dead zone saturation influence of an actuator, establishing a fixed time integral sliding mode approach law according to the saturation compensator to design a steering engine control law corresponding to a ship longitudinal propulsion and bow swinging channel, and realizing fault-tolerant control of under-actuated ship track tracking fixed time under output constraint according to the steering engine control law. The method solves the problems that the prior method can not process the constraint and fault influence of the actuator, adapt to disturbance mutation and uncertainty and the like at the same time, and reduces the safety and engineering realizability of the underactuated ship under the complex working condition.

Inventors

ZHANG XIANKU
LIU WENMING
MENG YAO
MA DAOCHENG

Assignees

大连海事大学

Dates

Publication Date: 20260505
Application Date: 20260123

Claims (6)

1. The fault-tolerant control method for tracking the under-actuated ship track under the output constraint for the fixed time is characterized by comprising the following steps: S1, acquiring an underactuated ship mathematical identification model which introduces dead zone and saturation characteristics into control input and simultaneously considers external disturbance and model uncertainty items; s2, constructing a fixed-time sliding mode fault observer according to the under-actuated ship mathematical identification model; S3, constructing a fixed time preset performance function based on a penta polynomial, and constructing a virtual control law of preset time performance according to an underactuated ship mathematical identification model based on the fixed time preset performance function; S4, defining a transverse speed error and a longitudinal speed error according to a virtual control law and combining a fixed time sliding mode fault observer; constructing a first fixed time integral sliding mode approach law according to the transverse speed error and the transverse saturation compensator; and S5, respectively designing steering engine control laws corresponding to the longitudinal propulsion and bow-sway channels of the ship according to the first fixed-time sliding mode approach law and the second fixed-time integral sliding mode approach law, and realizing fault-tolerant control for tracking the underactuated ship track under the output constraint for fixed time according to the steering engine control laws.
2. The method for controlling the track tracking and fixed time fault tolerance of the under-actuated ship under the output constraint according to claim 1, wherein the mathematical identification model of the under-actuated ship in S1 is as follows: Wherein u, v, r respectively represent the heave speed, the sway speed and the yaw angular speed; The transverse position, the longitudinal position and the heading angle of the touch massage are represented; , Representing the fault factor and ; Representing model identification parameters; Representing an external disturbance; , , Representing a model uncertainty term used for representing the existence of a system, wherein L (D (n)) represents a host rotation speed with dead zone saturation, and L (D (delta)) represents a rudder angle with dead zone saturation; Respectively represent Is a first order derivative of (a); Representing intermediate parameters; delta represents rudder angle; Representing a dead zone threshold; Representing the saturation value of the control input.
3. The method for controlling the under-actuated ship track tracking and fixed time fault tolerance under the output constraint according to claim 2, wherein the step S2 specifically comprises the steps of: S21, converting a dynamics model part in the under-actuated ship mathematical identification model into: wherein: , , all represent intermediate parameters, and , , Representing a known portion of the model; s22, writing the converted dynamic model part into a matrix form as follows: wherein: , , , , , Representation of , , In shorthand form; s23, defining observer errors of the underactuated ship based on S22 as follows: wherein: Representing observer errors of the underactuated vessel; Representation of Is a function of the estimated value of (2); s24, defining the observer error as a sliding mode surface, and constructing a fixed-time sliding mode fault observer according to the observer error as follows: wherein: Representation of Is a first order derivative of (a); Representing a parameter matrix of the design; Representing heave velocity error and ; Representation of Is used for the estimation of the estimated value of (a).
4. The method for controlling the under-actuated ship track tracking and fixed time fault tolerance under the output constraint according to claim 3, wherein the step S3 specifically comprises the following steps: s31, constructing a fixed time preset performance function based on a fifth order polynomial The method comprises the following steps: wherein: representing an initial value of a preset performance function of fixed time; Representing a final value of a fixed time preset performance function; Representing the result of normalizing the time; T represents a preset time; S32, defining a position tracking error according to the under-actuated ship mathematical identification model as follows: wherein: Representing a lateral position error and a longitudinal position error; representing the transverse coordinates and the longitudinal coordinates of the expected track; s33, obtaining the derivative of the position tracking error as follows: S34, presetting a performance function according to the fixed time The constraint conditions for the position tracking error are set as follows: wherein: representing intermediate parameters and , , , , Representation of In shorthand form and , Representing a fixed time preset performance function for the heave speed, the roll speed and the yaw angular speed of the under-actuated vessel; , Representing a positive design parameter; s35, designing a conversion function based on constraint conditions, wherein the conversion function is as follows: wherein: A conversion result indicating a position tracking error; And deriving the transfer function to obtain the derivative of the transfer function as: s36, obtaining the derivative of the simultaneous conversion function and the derivative of the position tracking error: wherein: Representing design parameters; S37, constructing a virtual control law of preset time performance according to the formula of S36, wherein the virtual control law is as follows: wherein: and outputting a virtual control law representing the preset time performance.
5. The method for controlling the under-actuated ship track following fixed time fault tolerance under the output constraint according to claim 4, wherein the step S4 specifically comprises the steps of: s41, defining a transverse speed error and a longitudinal speed error as follows according to a virtual control law and a fixed time sliding mode fault observer: wherein: Representing a lateral velocity error and a longitudinal velocity error; s42, constructing a transverse saturation compensator and a longitudinal saturation compensator for compensating the dead zone saturation influence of an actuator, wherein the transverse saturation compensator and the longitudinal saturation compensator are as follows: wherein: Representing the output of the lateral saturation compensator; Representing the output of the longitudinal saturation compensator; Representation of Is a first order derivative of (a); Representing a positive design parameter; s43, rewriting a transverse speed error and a longitudinal speed error into the following states according to the transverse saturation compensator and the longitudinal saturation compensator: s44, designing an integral sliding mode surface based on the S43 as follows: wherein: An integral slip plane representing the corresponding lateral velocity error and longitudinal velocity error; Representing a positive design parameter; S45, constructing a first fixed time integral sliding mode approach law according to the integral sliding mode surface Approach law with second fixed time integral sliding mode The method comprises the following steps: wherein: representing a positive design parameter.
6. The under-actuated ship track tracking fixed time fault-tolerant control method under output constraint according to claim 5, wherein the design formula of the steering engine control law corresponding to the ship longitudinal propulsion and bow yaw channel in S5 is as follows: wherein: And respectively representing steering engine control laws corresponding to the longitudinal propulsion and the bow-swing channels of the ship.

Description

Under-actuated ship track tracking fixed time fault-tolerant control method under output constraint Technical Field The invention relates to the technical field of under-actuated ship motion control, in particular to an under-actuated ship track tracking fixed time fault-tolerant control method under output constraint. Background The under-actuated ship track tracking and course maintaining control technology has important application value in the scenes of modern marine transportation, fine port manipulation, unmanned Surface Vessel (USV) autonomous navigation and the like. With the large-scale ships, complex navigation environments and the development of intelligent shipping technology, a control system not only needs to realize stable tracking under the conventional sea conditions, but also needs to keep high precision and robustness under the input constraint coexistence conditions of strong disturbance of wind and wave currents, uncertain model parameters, unmodeled dynamics, dead zones of actuators, saturation and the like. On the one hand, the faults such as propulsion or steering engine efficiency attenuation can lead to abrupt change or decline of equivalent control gain, further aggravate the coupling effect of an under-actuated system, and easily cause tracking error increase and control buffeting. On the other hand, the initial state error in engineering is difficult to accurately acquire, the existing methods can only ensure asymptotic or limited time convergence and the convergence time depends on an initial value, and cannot give fixed time performance guarantee irrelevant to the initial state, and in addition, the traditional preset performance control also faces challenges on whether the error can be strictly maintained in a given performance boundary in the whole time domain when an actuator is limited and fault disturbance is overlapped. In view of the above problems, development of a fixed time fault-tolerant control method capable of simultaneously processing constraint and fault influence of an actuator, adapting disturbance mutation and uncertainty, and realizing controllable convergence time and independence from an initial value under strict output constraint is needed to improve safety and engineering realizability of an under-actuated ship under complex working conditions. Disclosure of Invention The invention provides an under-actuated ship track tracking fixed time fault-tolerant control method under output constraint so as to overcome the technical problems. In order to achieve the above object, the technical scheme of the present invention is as follows: an under-actuated ship track tracking fixed time fault-tolerant control method under output constraint comprises the following steps: S1, acquiring an underactuated ship mathematical identification model which introduces dead zone and saturation characteristics into control input and simultaneously considers external disturbance and model uncertainty items; s2, constructing a fixed-time sliding mode fault observer according to the under-actuated ship mathematical identification model; S3, constructing a fixed time preset performance function based on a penta polynomial, and constructing a virtual control law of preset time performance according to an underactuated ship mathematical identification model based on the fixed time preset performance function; s4, defining a transverse speed error and a longitudinal speed error according to a virtual control law, and simultaneously constructing a transverse saturation compensator and a longitudinal saturation compensator for compensating the dead zone saturation influence of an actuator; constructing a first fixed time integral sliding mode approach law according to the transverse speed error and the transverse saturation compensator; and S5, respectively designing steering engine control laws corresponding to the longitudinal propulsion and bow-sway channels of the ship according to the first fixed-time sliding mode approach law and the second fixed-time integral sliding mode approach law, and realizing fault-tolerant control for tracking the underactuated ship track under the output constraint for fixed time according to the steering engine control laws. Further, the mathematical identification model of the under-actuated ship in S1 is as follows: Wherein u, v, r respectively represent the heave speed, the sway speed and the yaw angular speed; The transverse position, the longitudinal position and the heading angle of the touch massage are represented; , Representing the fault factor and ;Representing model identification parameters; Representing an external disturbance; ,, Representing a model uncertainty term used for representing the existence of a system, wherein L (D (n)) represents a host rotation speed with dead zone saturation, and L (D (delta)) represents a rudder angle with dead zone saturation; Respectively represent Is a first order derivative of (a); Representing in