CN110333658A - A kind of underactuated surface vessel course heading control method compensated with input constraint and drift angle - Google Patents

Abstract

The invention proposes a kind of underactuated surface vessel course heading control methods compensated with input constraint and drift angle, based on Reverse Step Control algorithm, it introduces hyperbolic tangent function and converts continuous function for discontinuous input saturation function, combining adaptive rule estimates the external disturbance on yawing direction, the Heading control algorithm proposed can make underactuated surface vessel remain lesser control input torque while following the navigation of setting course, and motion control performance greatly improves.

Description

A kind of underactuated surface vessel course heading control method compensated with input constraint and drift angle

Technical field

It is related to ship control field, and in particular to a kind of underactuated surface vessel Heading control compensated with input constraint and drift angle Method.

Background technique

As maritime traffic is increasingly intensive, by more and more the problem of relating to how to more preferably realize ship course keeping control The concern of person.Most traditional ship in real life is usually under-actuated systems, i.e., only horizontal by a control input control It swings and the movement on two direction of yawing.It would generally ignore the presence of drift angle in Heading control, but practical drift angle and be not zero, in this way Ship actual motion direction and desired course can be made to differ a drift angle, if Heading control performance will be reduced without amendment. One of input saturation even more actual control system common phenomenon, any actuator have certain executable range, once Input goes beyond the limit of value, just will affect the operation of actuator, system performance is caused to reduce, influence control effect, and protect for a long time Holding excessive control input also will increase the loss of rudder.

Summary of the invention

The invention proposes a kind of underactuated surface vessel Heading control sides compensated with input constraint and drift angle, are based on contragradience control Algorithm processed introduces hyperbolic tangent function for discontinuous input saturation function and is converted into continuous function, and combining adaptive is restrained to bow The external disturbance shaken on direction is estimated that the Heading control algorithm proposed can make underactuated surface vessel follow setting course boat Remain lesser control input torque while row, motion control performance greatly improves.

It mainly comprises the steps that

Step 1 establishes Ship autopilots；

Heaving, rolling, the movement on pitching direction are ignored, the two-freedom movement in swaying and yawing direction Underactuated surface vessel kinetic model can sum up as follows:

Wherein r is yawing angular frequency, u_rAnd v_rIt is opposite surging and swaying speed of the ship relative to hull coordinate system；ψ table Show ship actual heading angle, for i=11,22,33, parameter m_iIndicate marine system inertia, d_iIt is in yawing, surging and swaying Hydrodynamic damping, ω_rAnd ω_vRespectively there is the external disturbance of Unknown Bound in yawing and swaying direction；It is that actual control is defeated Enter,It is the output for being saturated actuator, τ_MFor the dividing value for controlling input constraint.

Step 2 introduces hyperbolic tangent function, converts continuous function for control input saturation constraints；

Introduce hyperbolic tangent functionCarry out the non-linear partial of approximate saturation function, as follows

So willTwo parts are defined as, i.e.,

WhereinFor approximate error, it is assumed that its bounded, then formula (1) can rewrite as follows:

WhereinBounded, it is assumed that Δ≤σ, definitionFor the estimated value of σ, evaluated error is C is normal number, and φ is auxiliary signal.

Step 3 assigns desired course instruction, i.e. setting desired course angle ψ_d；

Step 4 considers influence of the ocean current to drift angle, drift angle β is calculated, using drift angle to desired course angle ψ_dIt compensates；

Wherein u_rAnd v_rIt is practical swaying and surging speed of the ship relative to hull coordinate system, v respectively_cAnd β_cIt is opposite In the wave speed of earth coordinates and azimuth, can be obtained in conjunction with above formula

ψ_da=ψ_d-β (7)

Step 5, design Heading control algorithm；

New variables, which is introduced, in conjunction with step 4 carries out state conversion

z₁=∫ ψ dt- ∫ ψ_dadt (8)

z₂=ψ-ψ_da-α₁ (9)

z₃=r- α₂ (10)

Wherein z_i, i=1,2,3,4, it is auxiliary variable, α_i, i=1,2,3 indicate virtually calm function, specific as follows

α₁=-k₁z₁ (12)

Wherein constant k₁> 0, k₂> 0, k₃> 0, υ > 0；

Design adaptive lawFor

Wherein constant γ_f> 0；

Then auxiliary signal φ is

Wherein constant k₄> 0.

Step 6, control system execute instruction, real-time update course angle ψ, yawing angular frequency r and swaying speed v_r, and go to Step 4.

This method has the following effects that and advantage:

By introduce hyperbolic tangent function to control input saturation constraints approach, meet Backstepping design in for The guidable requirement of all functions, and combining adaptive rule carries out estimation processing to the disturbance on yawing direction, by based on anti- The course heading control method of footwork, making system in a relatively short period of time makes to reach stable state, and course output error greatly reduces, together When remain lesser control input torque, effectively improve control performance.

Detailed description of the invention

Fig. 1 is the Heading control schematic diagram that ship does not compensate drift angle

Fig. 2 is the Heading control schematic diagram after present invention compensation drift angle

Specific embodiment

The invention proposes a kind of underactuated surface vessel course heading control methods compensated with input constraint and drift angle, introduce hyperbolic Discontinuous input saturation function is converted continuous function by tangent function, and combining adaptive rule disturbs the outside on yawing direction It is dynamic to be estimated, complete direction controller is designed in conjunction with Backstepping, comprising the following steps:

Step 1 establishes Ship autopilots；

Heaving, rolling, the movement on pitching direction are ignored, the two-freedom movement in swaying and yawing direction Underactuated surface vessel kinetic model can sum up as follows:

Wherein r is yawing angular frequency, u_rAnd v_rIt is opposite surging and swaying speed of the ship relative to hull coordinate system；ψ table Show ship actual heading angle, for i=11,22,33, parameter m_iIndicate marine system inertia, d_iIt is in yawing, surging and swaying Hydrodynamic damping, ω_rAnd ω_vRespectively there is the external disturbance of Unknown Bound in yawing and swaying direction；It is that actual control is defeated Enter,It is the output for being saturated actuator, τ_MFor the dividing value for controlling input constraint.

Step 2 introduces hyperbolic tangent function, converts continuous function for control input saturation constraints；

Introduce hyperbolic tangent functionCarry out the non-linear partial of approximate saturation function, as follows

So willTwo parts are defined as, i.e.,

WhereinFor approximate error, it is assumed that its bounded, then formula (1) can rewrite as follows:

WhereinBounded, it is assumed that Δ≤σ, definitionFor the estimated value of σ, evaluated error is C is normal number, and φ is auxiliary signal.

Step 3 assigns desired course instruction, i.e. setting desired course angle ψ_d；

Step 4 considers influence of the ocean current to drift angle, drift angle β is calculated, using drift angle to desired course angle ψ_dIt compensates；

Wherein u_rAnd v_rIt is practical swaying and surging speed of the ship relative to hull coordinate system, v respectively_cAnd β_cIt is opposite Current speed and azimuth in earth coordinates, can obtain in conjunction with above formula

ψ_da=ψ_d-β (7)

Step 5, design Heading control algorithm；

New variables, which is introduced, in conjunction with step 4 carries out state conversion

z₁=∫ ψ dt- ∫ ψ_dadt (8)

z₂=ψ-ψ_da-α₁ (9)

z₃=r- α₂ (10)

Wherein z_i, i=1,2,3,4 be auxiliary variable, α_i, i=1,2,3 indicate virtually calm function, specific as follows

α₁=-k₁z₁ (12)

Wherein constant k₁> 0, k₂> 0, k₃> 0, υ > 0；

Design adaptive lawFor

Wherein constant γ_f> 0；

Then auxiliary signal φ is

Wherein constant k₄> 0.

Step 6, control system execute instruction, real-time update course angle ψ, yawing angular frequency r and swaying speed v_r, and go to Step 4.

Claims (1)

1. a kind of underactuated surface vessel course heading control method compensated with input constraint and drift angle, it is characterised in that:

Step 1 establishes Ship autopilots；

Heaving, rolling, the movement on pitching direction are ignored, the deficient drive of the two-freedom movement in swaying and yawing direction Dynamic ship dynamics model can sum up as follows:

Wherein r is yawing angular frequency, u_rAnd v_rIt is opposite surging and swaying speed of the ship relative to hull coordinate system；ψ indicates ship Actual heading angle, for i=11,22,33, parameter m_iIndicate marine system inertia, d_iIt is the hydrodynamic force in yawing, surging and swaying Damping, ω_rAnd ω_vRespectively there is the external disturbance of Unknown Bound in yawing and swaying direction；It is actual control input, It is the output for being saturated actuator, τ_MFor the dividing value for controlling input constraint；

Step 2 introduces hyperbolic tangent function, converts continuous function for control input saturation constraints；

Hyperbolic tangent functionCarry out the non-linear partial of approximate saturation function, as follows

So willTwo parts are defined as, i.e.,

WhereinFor approximate error, it is assumed that its bounded, then formula (1) can rewrite as follows:

WhereinBounded, it is assumed that Δ≤σ, definitionFor the estimated value of σ, evaluated error is C is normal number, and φ is auxiliary signal；

Step 3 assigns desired course instruction, i.e. setting desired course angle ψ_d；

Step 4 considers influence of the ocean current to drift angle, drift angle β is calculated, using drift angle to desired course angle ψ_dIt compensates；

Wherein u and v is practical surging and swaying speed of the ship relative to hull coordinate system, v respectively_cAnd β_cIt is relative to the earth The wave speed of coordinate system and azimuth can be obtained in conjunction with above formula

ψ_da=ψ_d-β (7)

Step 5, design Heading control algorithm；

New variables, which is introduced, in conjunction with step 4 carries out state conversion

z₁=∫ ψ dt- ∫ ψ_dadt (8)

z₂=ψ-ψ_da-α₁ (9)

z₃=r- α₂ (10)

Wherein z_i, i=1,2,3,4 be auxiliary variable, α_i, i=1,2,3 indicate virtually calm function, specific as follows

α₁=-k₁z₁ (12)

Wherein constant k₁> 0, k₂> 0, k₃> 0, υ > 0；

Design adaptive lawFor

Wherein constant γ_f> 0；

Then auxiliary signal φ is

Wherein constant k₄> 0；

Step 6, control system execute instruction, real-time update course angle ψ, yawing angular frequency r and swaying speed v_r, and go to step 4。