Method and device to assist in the driving of a vehicle, in particular of an aircraft, for the avoidance of obstacles

1. A method to assist in driving a vehicle moving along an initial trajectory, in an environment containing at least one obstacle to be avoided, the method comprising the steps of:

A/ checking, by a trajectory checking unit, during movement of the vehicle along the initial trajectory, in the environment containing the at least one obstacle to be avoided, the existence of at least one condition for modifying the initial trajectory of the vehicle;

B/ determining:

a) by a criteria determining unit, a criterion CR by which to avoid the at least one obstacle, wherein the criterion CR is determined according to the following expression:

CR=R 2 +a 1· D 2 +a 2· T 2

in which:

R is an evaluation of a risk of collision with the at least one obstacle;

D is an evaluation of a deviation relative to the initial trajectory;

T is time needed to rejoin the initial trajectory; and

a 1 and a 2 are weighting values; and

b) by an avoidance trajectory determining unit, an avoidance trajectory according to a value E wherein:

E=∂CR/∂s∂q

in which:

s is a curvilinear abscissa of the vehicle moving along the initial trajectory;

q represents a turn parameter of a control element that controls the vehicle (to follow said avoidance trajectory; and

E represents a derivative of the criterion CR in relation both to said curvilinear abscissa s and to said turn parameter q;

wherein said avoidance trajectory determining unit further determines values of the turn parameter q for which said derivative value E is zero, said turn parameter values being incorporated into the determination of the avoidance trajectory in which the vehicle reaches a planned destination while avoiding said at least one obstacle; and

C/ assisting the driving of the vehicle by a driving assist device along the determined avoidance trajectory according to the determined values of the turn parameter in conjunction with the corresponding curvilinear abscissi.

2. The method as claimed in claim 1 ,

wherein, in the step A/, the checking is carried out to determine the existence of at least one of the following conditions:

a minimum safety distance is not observed relative to the at least one obstacle; and

at least one traffic rule in the environment is not observed.

3. The method as claimed in claim 1 ,

wherein a plurality of control elements of the vehicle are provided with which to modify the initial trajectory and said control elements are actuated in accordance with the determined criterion CR and the turn parameter q such that:

∂ CR/∂q=O.

4. The method as claimed in claim 3 ,

wherein said vehicle is an aircraft, and wherein said control elements include at least one control surface of the aircraft.

5. The method as claimed in claim 1 ,

wherein, in the step C/, at least one indication representing said avoidance trajectory is presented to a pilot of the vehicle on a display system.

6. The method as claimed in claim 1 ,

wherein, in the step C/, an automatic piloting system assists in the driving of the vehicle along said avoidance trajectory.

7. The method as claimed in claim 1 , wherein said initial trajectory and said avoidance trajectory are flight trajectories.

8. The method as claimed in claim 1 ,

wherein said initial trajectory and said avoidance trajectory are taxiing trajectories.

9. A device to assist in piloting a vehicle moving along an initial trajectory, in an environment containing at least one obstacle to be avoided, said device comprising:

trajectory checking unit configured to check, during movement of the vehicle along the initial trajectory, in the environment containing the at least one obstacle to be avoided, the existence of at least one condition for modifying the initial trajectory of the vehicle;

criterion determining unit configured to calculate a criterion CR by which to avoid the at least one obstacle, wherein the criterion CR is determined according to the following expression:

CR=R 2 +a 1· D 2 +a 2· T 2

in which:

R is an evaluation of a risk of collision with the at least one obstacle;

D is an evaluation of a deviation relative to the initial trajectory;

T is time needed to rejoin the initial trajectory; and

a 1 and a 2 are weighting values;

avoidance trajectory determining unit configured to determine an avoidance trajectory according to a value E in which:

E=∂CR/∂s∂q

in which:

s is a curvilinear abscissa of the vehicle moving along the initial trajectory;

q represents a turn parameter of a control element that controls the vehicle to follow said avoidance trajectory; and

E represents a derivative of the criterion CR relative both to said curvilinear abscissa s and to said turn parameter q;

wherein said avoidance trajectory determining unit further determines values of the turn parameter q, for which said derivative value E is zero, said turn parameter values being incorporated into the determination of the avoidance trajectory in which the vehicle reaches a planned destination while avoiding said obstacle; and

driving assist device configured to receive the determined values of the turn parameter in conjunction with the corresponding curvilinear abscissa from the avoidance trajectory determining unit, and to assist driving of the vehicle along the determined avoidance trajectory.

10. An aircraft, which includes the device of claim 9 .