Aircraft wake sensing

1 . A method of sensing a wake produced by a leader aircraft and experienced by a follower aircraft, the method comprising:

providing a model simulating a dynamic behavior of the follower aircraft, the model operating on variables representing the following six degrees of freedom of the follower aircraft: position on a longitudinal axis, position on a transverse axis, position on a height axis, angle of roll, angle of pitch, and angle of yaw, the model further operating on time derivatives of the six degrees of freedom;

repetitively carrying out the following three operations in an iterative manner:

using the model simulating the dynamic behavior of the follower aircraft to simulate a response of the follower aircraft to an estimated aerodynamic context exclusively based on data only from the follower aircraft free from any data communicated by the leader aircraft, an estimated position of the follower aircraft with respect to a model of the wake, and data indicating aerodynamic effects experienced by the follower aircraft due to motion of the follower aircraft;

estimating measurements carried out by the follower aircraft based on the simulated response of the follower aircraft to the estimated aerodynamic context, whereby the measurements that are estimated are dependent on the position of the follower aircraft relative to the wake; and

adjusting the estimated aerodynamic context based on a comparison between the measurements that have been estimated and actual measurements carried out by the follower aircraft to reduce a deviation between the measurements that have been estimated and the actual measurements;

extracting information on the wake from the estimated aerodynamic context; and

using the information on the wake obtained to define a target for a flight controller in the follower aircraft.

2 . The method of sensing the wake according to claim 1 , wherein the model of the wake comprises at least one vortex tube positioned with respect to a reference axis, the estimated position of the follower aircraft being relative to the reference axis.

3 . The method of sensing the wake according to claim 1 , wherein the simulated response of the follower aircraft is based on an aerodynamic model of the follower aircraft and a control behavior implemented by a flight control module in the follower aircraft.

4 . The method of sensing the wake-according to claim 3 , wherein the aerodynamic model of the follower aircraft is based on at least one of the following aerodynamic modelling techniques: Prandtl's lifting line, doublet lattice method, and vortex lattice method, an empirical model based on calibrated coefficients.

5 . The method of sensing the wake according to claim 1 , wherein the measurements that are estimated and actually carried out comprise measurements typically carried out by commercial aircraft including at least one of the following measurements: angle of incidence, angle of slip, inertial position, velocity, attitude, angular velocity, translational acceleration, and angular acceleration.

6 . The method of sensing the wake according to claim 1 , wherein the estimating and the adjusting is done by means of a recursive filter.

7 . The method of sensing the wake according to claim 6 , wherein the recursive filter is one of the following: an ensemble Kalman filter, an unscented Kalman filter, a particle filter, and a neural-network based filter.

8 . The method of sensing the wake according to claim 6 , wherein the recursive filter operates on a state vector that comprises at least one variable of the model of the wake, at least one variable expressing the position of the follower aircraft with respect to the model of the wake, and a set of variables of a model of the follower aircraft as a dynamic system.

9 . The method of sensing the wake-according to claim 1 , wherein the method is carried out by a flight computer in the follower aircraft.

10 . A method of controlling a flight of a follower aircraft that flies behind a leader aircraft, the method comprising:

obtain information on a wake produced by the leader aircraft and experienced by the follower aircraft by;

providing a model simulating a dynamic behavior of the follower aircraft, the model operating on variables representing the following six degrees of freedom of the follower aircraft: position on a longitudinal axis, position on a transverse axis, position on a height axis, angle of roll, angle of pitch, and angle of yaw, the model further operating on time derivatives of the six degrees of freedom;

repetitively carrying out the following three operations in an iterative manner:

using the model simulating the dynamic behavior of the follower aircraft to simulate a response of the follower aircraft to an estimated aerodynamic context exclusively based on data only from the follower aircraft free from any data communicated by the leader aircraft, an estimated position of the follower aircraft with respect to a model of the wake, and data indicating aerodynamic effects experienced by the follower aircraft due to motion of the follower aircraft;

estimating measurements carried out by the follower aircraft based on the simulated response of the follower aircraft to the estimated aerodynamic context, whereby the measurements that are estimated are dependent on the position of the follower aircraft relative to the wake; and

adjusting the estimated aerodynamic context based on a comparison between the measurements that have been estimated and actual measurements carried out by the follower aircraft to reduce a deviation between the measurements that have been estimated and the actual measurements;

extracting the information on the wake from the estimated aerodynamic context; and

using the information on the wake obtained to define a target for a flight controller in the follower aircraft.

11 . The method of controlling the flight according to claim 10 , wherein using the information on the wake comprises:

filtering the information on the wake that is extracted from the estimated aerodynamic context; and

at least one of the following operations based on information on the wake that has been filtered:

detecting generic patterns of the wake; and

detecting at least a turbulence characteristic in the wake.

12 . A non-transitory machine readable storage medium on which a computer program is stored, the computer program enabling a processor to;

provide a model simulating a dynamic behavior of a follower aircraft, the model operating on variables representing the following six degrees of freedom of the follower aircraft: position on a longitudinal axis, position on a transverse axis, position on a height axis, angle of roll, angle of pitch, and angle of yaw, the model further operating on time derivatives of the six degrees of freedom;

repetitively carry out the following three operations in an iterative manner:

use the model simulating the dynamic behavior of the follower aircraft to simulate a response of the follower aircraft to an estimated aerodynamic context exclusively based on data only from the follower aircraft free from any data communicated by a leader aircraft, an estimated position of the follower aircraft with respect to a model of the wake, and data indicating aerodynamic effects experienced by the follower aircraft due to motion of the follower aircraft;

estimate measurements carried out by the follower aircraft based on the simulated response of the follower aircraft to the estimated aerodynamic context, whereby the measurements that are estimated are dependent on the position of the follower aircraft relative to the wake; and

adjust the estimated aerodynamic context based on a comparison between the measurements that have been estimated and actual measurements carried out by the follower aircraft to reduce a deviation between the measurements that have been estimated and the actual measurements;

extract the information on the wake from the estimated aerodynamic context; and

use the information on the wake obtained to define a target for a flight controller in the follower aircraft.

13 . A flight computer adapted to;

provide a model simulating a dynamic behavior of a follower aircraft, the model operating on variables representing the following six degrees of freedom of the follower aircraft: position on a longitudinal axis, position on a transverse axis, position on a height axis, angle of roll, angle of pitch, and angle of yaw, the model further operating on time derivatives of the six degrees of freedom;

repetitively carry out the following three operations in an iterative manner:

use the model simulating the dynamic behavior of the follower aircraft to simulate a response of the follower aircraft to an estimated aerodynamic context exclusively based on data only from the follower aircraft free from any data communicated by a leader aircraft, an estimated position of the follower aircraft with respect to a model of the wake, and data indicating aerodynamic effects experienced by the follower aircraft due to motion of the follower aircraft;

estimate measurements carried out by the follower aircraft based on the simulated response of the follower aircraft to the estimated aerodynamic context, whereby the measurements that are estimated are dependent on the position of the follower aircraft relative to the wake; and

adjust the estimated aerodynamic context based on a comparison between the measurements that have been estimated and actual measurements carried out by the follower aircraft to reduce a deviation between the measurements that have been estimated and the actual measurements;

extract the information on the wake from the estimated aerodynamic context; and

use the information on the wake obtained to define a target for a flight controller in the follower aircraft.

14 . A non-transitory machine readable storage medium on which a computer program is stored, the computer program enabling a processor to;

obtain information on a wake produced by a leader aircraft and experienced by a follower aircraft by;

providing a model simulating a dynamic behavior of the follower aircraft, the model operating on variables representing the following six degrees of freedom of the follower aircraft: position on a longitudinal axis, position on a transverse axis, position on a height axis, angle of roll, angle of pitch, and angle of yaw, the model further operating on time derivatives of the six degrees of freedom;

repetitively carrying out the following three operations in an iterative manner:

using the model simulating the dynamic behavior of the follower aircraft to simulate a response of the follower aircraft to an estimated aerodynamic context exclusively based on data only from the follower aircraft free from any data communicated by the leader aircraft, an estimated position of the follower aircraft with respect to a model of the wake, and data indicating aerodynamic effects experienced by the follower aircraft due to motion of the follower aircraft;

estimating measurements carried out by the follower aircraft based on the simulated response of the follower aircraft to the estimated aerodynamic context, whereby the measurements that are estimated are dependent on the position of the follower aircraft relative to the wake; and

adjusting the estimated aerodynamic context based on a comparison between the measurements that have been estimated and actual measurements carried out by the follower aircraft to reduce a deviation between the measurements that have been estimated and the actual measurements;

extracting the information on the wake from the estimated aerodynamic context; and

using the information on the wake obtained to define a target for a flight controller in the follower aircraft.

15 . A flight computer adapted to;

obtain information on a wake produced by a leader aircraft and experienced by a follower aircraft by;

providing a model simulating a dynamic behavior of the follower aircraft, the model operating on variables representing the following six degrees of freedom of the follower aircraft: position on a longitudinal axis, position on a transverse axis, position on a height axis, angle of roll, angle of pitch, and angle of yaw, the model further operating on time derivatives of the six degrees of freedom;

repetitively carrying out the following three operations in an iterative manner:

using the model simulating the dynamic behavior of the follower aircraft to simulate a response of the follower aircraft to an estimated aerodynamic context exclusively based on data only from the follower aircraft free from any data communicated by the leader aircraft, an estimated position of the follower aircraft with respect to a model of the wake, and data indicating aerodynamic effects experienced by the follower aircraft due to motion of the follower aircraft;

estimating measurements carried out by the follower aircraft based on the simulated response of the follower aircraft to the estimated aerodynamic context, whereby the measurements that are estimated are dependent on the position of the follower aircraft relative to the wake; and

adjusting the estimated aerodynamic context based on a comparison between the measurements that have been estimated and actual measurements carried out by the follower aircraft to reduce a deviation between the measurements that have been estimated and the actual measurements;

extracting the information on the wake from the estimated aerodynamic context; and

using the information on the wake obtained to define a target for a flight controller in the follower aircraft.