Method and device for generating a taxiing speed for an aircraft of a convoy

1. A method of generating a controlled speed for a following aircraft (Ai) taxiing on the ground in a convoy of aircraft (CA), whereby the following successive steps are performed automatically and repetitively:

a) the current values of first parameters corresponding to parameters of at least one followed aircraft (Ai- 1 , A 1 ) of said convoy (CA), which precedes said following aircraft (Ai) in said convoy (CA), are received;

b) at least one longitudinal separation (Di) which must be observed between said followed aircraft (Ai- 1 ) and said following aircraft (Ai) is generated;

c) the current values of second parameters which correspond to parameters of said following aircraft (Ai) are measured; and

d) using said current values of the first and second parameters and said longitudinal separation (Di), a controlled speed is calculated which represents a longitudinal speed instruction enabling the following aircraft (Ai) to taxi along a trajectory (TR) common to said convoy (CA) while maintaining said longitudinal separation (Di) relative to said followed aircraft,

wherein, in the step d), said controlled speed v i is calculated using the following expression:

v

i

=

1

-

y

~

i

⁢

c

⁡

(

s

i

)

cos

⁡

(

ψ

~

i

)

⁡

[

1

+

A

⁡

(

z

i

)

⁢

(

s

1

-

s

i

-

1

-

∑

n

=

1

i

-

1

⁢

D

n

)

]

⁢

(

σ

i

⁢

v

1

⁢

cos

⁡

(

ψ

~

1

)

1

-

y

~

1

⁢

c

⁡

(

s

1

)

+

[

1

-

σ

i

+

A

⁢

(

z

i

)

⁢

(

s

1

-

s

i

-

1

-

∑

n

=

1

i

-

1

⁢

D

n

)

]

⁢

v

i

-

1

⁢

cos

⁡

(

ψ

~

i

-

1

)

1

-

y

~

i

-

1

⁢

c

⁡

(

s

i

-

1

)

+

k

i

⁢

c

i

)

in which:

{tilde over (y)} i : is the lateral separation for an aircraft of rank i;

{tilde over (y)} i-1 : is the lateral separation for an aircraft of rank i- 1 ;

v i : is the longitudinal speed for the aircraft of rank i;

v i-1 : is the longitudinal speed for the aircraft of rank i- 1 ;

c(s i ): is the curvature at a current point for the aircraft of rank i;

c(s i-1 ): is the curvature at the current point for the aircraft of rank i- 1 ;

{tilde over (ψ)} i : is the angular separation for the aircraft of rank i;

{tilde over (ψ)} i-1 : is the angular separation for the aircraft of rank i- 1 ;

s i-1 : is the curvilinear abscissa for an aircraft of rank i- 1 ;

s 1 : is the curvilinear abscissa for the leader aircraft;

{tilde over (ψ)} 1 : is the angular separation for the leader aircraft;

υ 1 : is the longitudinal speed for the leader aircraft;

c(s 1 ): is the curvature at the current point of the leader aircraft;

A(z i ): is a quantity;

σ i : is a regulation parameter;

{tilde over (y)} i : is the lateral separation for the leader aircraft;

k i : is a gain;

ci: is an appropriate set point; and

D i : is the longitudinal separation between the leader aircraft of rank i- 1 and an aircraft of rank i.

2. The method as claimed in claim 1 ,

wherein, in the step b), a fixed value is received for said longitudinal separation.

3. The method as claimed in claim 1 ,

wherein, in the step b), said longitudinal separation Di is calculated using the following expression:

Di=di+ƒ ( vi )

in which:

di is a fixed distance to be observed between the followed aircraft and the following aircraft;

vi is the current speed of the following aircraft; and

ƒ(vi) is a parameter that varies according to a function f that increases in relation to said current speed vi of the following aircraft.

4. The method as claimed in claim 1 ,

wherein said regulation parameter σ i is defined between 0 and 1 and can be used to adjust the predominance between a step-by-step command and a leader-referenced command.

5. The method as claimed in claim 1 ,

wherein said regulation parameter σ i corresponds to one of the following transitions:

a linear transition;

a sigmoidal transition; and

a pseudo-sigmoidal transition.

6. The method as claimed in claim 5 ,

wherein, in the step d), said gain k i is determined so as to avoid a saturation in speed and in acceleration.

7. The method as claimed in claim 6 ,

wherein, in the step d), acceleration is monitored, so as to enable the deceleration authority of the following aircraft to be widened in case of risk of collision with a followed aircraft.

8. An automatic longitudinal guidance method for an aircraft (Ai) taxiing on the ground in a convoy of aircraft (CA),

wherein the following series of successive operations is performed automatically and repetitively:

A/ a controlled speed is generated, implementing the method specified as claimed in claim 1 ;

B/ set points are calculated that are likely to be applied to control means ( 11 ) that act on the speed of the aircraft (Ai), said set points being such that, when applied to said control means ( 11 ), the latter pilot the aircraft longitudinally according to said controlled speed; and

C/ the duly calculated set points are applied to said control means ( 11 ).

9. A device for generating a controlled speed for a following aircraft (Ai) taxiing on the ground in a convoy of aircraft (CA), said device ( 1 ) comprising:

first means ( 12 ) for receiving the current values of first parameters corresponding to parameters of at least one followed aircraft (Ai- 1 , Ai) of said convoy (CA), that precedes said following aircraft (Ai) in said convoy (CA);

second means ( 3 ) for generating at least one longitudinal separation (Di) which must be observed between said followed aircraft (Ai- 1 ) and said following aircraft (Ai);

third means ( 4 ) for measuring the current values of second parameters which correspond to parameters of said following aircraft (Ai); and

fourth means ( 5 ) for calculating, using said current values of the first and second parameters and said longitudinal separation (Di), a controlled speed which represents a longitudinal speed instruction enabling the following aircraft (Ai) to taxi along a trajectory (TR) common to said convoy (CA) while maintaining said longitudinal separation (Di) relative to said followed aircraft,

wherein said fourth means ( 5 ) are formed in such a way as to calculate said controlled speed v i using the following expression:

v

i

=

1

-

y

~

i

⁢

c

⁡

(

s

i

)

cos

⁡

(

ψ

~

i

)

⁡

[

1

+

A

⁡

(

z

i

)

⁢

(

s

1

-

s

i

-

1

-

∑

n

=

1

i

-

1

⁢

D

n

)

]

⁢

(

σ

i

⁢

v

1

⁢

cos

⁡

(

ψ

~

1

)

1

-

y

~

1

⁢

c

⁡

(

s

1

)

+

[

1

-

σ

i

+

A

⁢

(

z

i

)

⁢

(

s

1

-

s

i

-

1

-

∑

n

=

1

i

-

1

⁢

D

n

)

]

⁢

v

i

-

1

⁢

cos

⁡

(

ψ

~

i

-

1

)

1

-

y

~

i

-

1

⁢

c

⁡

(

s

i

-

1

)

+

k

i

⁢

c

i

)

in which:

{tilde over (y)} i : is the lateral separation for an aircraft of rank i;

{tilde over (y)} i-1 : is the lateral separation for an aircraft of rank i- 1 ;

v i : is the longitudinal speed for the aircraft of rank i;

v i-1 : is the longitudinal speed for the aircraft of rank i- 1 ;

c(s i ) is the curvature at a current point for the aircraft of rank i;

c(s i-1 ): is the curvature at the current point for the aircraft of rank i- 1 ;

{tilde over (ψ)} i : is the angular separation for the aircraft of rank i;

{tilde over (ψ)} i-1 : is the angular separation for the aircraft of rank i- 1 ;

s i-1 : is the curvilinear abscissa for an aircraft of rank i- 1 ;

s 1 : is the curvilinear abscissa for the leader aircraft;

{tilde over (ψ)} 1 : is the angular separation for the leader aircraft;

υ 1 : is the longitudinal speed for the leader aircraft;

c(s 1 ): is the curvature at the current point of the leader aircraft;

A(z i ): is a quantity;

σ i : is a regulation parameter;

{tilde over (y)} 1 : is the lateral separation for the leader aircraft;

k i : is a gain;

ci: is an appropriate set point; and

D i : is the longitudinal separation between the leader aircraft of rank i- 1 and an aircraft of rank i.

10. An automatic longitudinal guidance system for an aircraft (Ai) taxiing on the ground in a convoy of aircraft (CA),

which comprises:

a device ( 1 ) such as that specified under claim 9 , for generating a controlled speed;

control means ( 11 ) which act on the speed of the aircraft;

means ( 12 ) for calculating set points likely to be applied to said control means ( 11 ), said set points being such that, when applied to said control means ( 11 ), the latter pilot the aircraft longitudinally according to said controlled speed; and

means ( 13 ) for applying the duly calculated set points to said control means ( 11 ).