Method and device for attenuating on an aircraft the effects of a vertical turbulence

CA 02622110 2008-03-11 WO 2007/042652 PCT / FR2006 / 002256 Method and device for attenuating the effects of vertical turbulence on an aircraft.

The present invention relates to a method and a device for attenuating on an aircraft the effects of at least one vertical turbulence encountered by this aircraft during a flight.

We know that during a flight violent turbulence linked to vertical wind gusts can cause the aircraft:

- significant variations in vertical load factor liable to cause injury to passengers in the aircraft;

a significant deviation of the aircraft at altitude, which increases the risk of collision with another aircraft; and - peaks in lift on the canopy, which test the load limits of the latter.

These violent turbulences can appear in clear skies and remain unpredictable.

Often, these phenomena, which are localized, surprise both the crew of the aircraft and the on-board piloting systems, which do not have time to perform the appropriate maneuvers to mitigate the resulting effects on the aircraft. 'aircraft.

Note that, for a transport aircraft, the appearance of negative vertical load factors is very dangerous for passengers who are not firmly attached.

They can be thrown on the ceiling and risk serious injury.

The aforementioned problems are accentuated by the diversity of possible vertical turbulence profiles.

The object of the present invention is to remedy these drawbacks.

It relates to a method making it possible to attenuate, in a particularly effective manner, on an aircraft, in particular a transport aircraft, CA 02622110 2008-03-11 WO 2007/042652 PCT / FR2006 / 002256 2 the effects of at least one turbulence vertical encountered by this aircraft during a flight.

To this end, according to the invention, said method is remarkable in that the following sequence of successive steps is carried out during flight, automatically and iteratively:

a) determining a vertical component of the wind existing outside the aircraft at a current position of said aircraft;

b) using this vertical component of the wind, a level of severity relating to a vertical turbulence existing outside the aircraft at said current position is determined;

c) with the aid of said vertical component of the wind, at least one control order is calculated for at least one controllable mobile member which is capable of acting on the lift of the aircraft, said control order being such that it makes it possible to minimize the amplitude of the load factors generated on the aircraft by the vertical turbulence; and d) it is checked whether the activation conditions depending at least on said level of severity are fulfilled; and e) if said activation conditions are fulfilled, said control command is transmitted to at least one actuator of said controllable movable member.

Thus, by virtue of the invention, a level of severity of the vertical turbulence is determined in order to know whether it is necessary to implement actions to attenuate the effects of the vertical turbulence.

When such actions are necessary, action is taken (via said movable member) on the total lift of the aircraft, which makes it possible to minimize the amplitude of the vertical load factor at any point in the cabin of the aircraft. .

The present invention thus makes it possible to combat the sudden variations in vertical load factor, generated by violent vertical turbulence of the aforementioned type.

CA 02622110 2008-03-11 WO 2007/042652 PCT / FR2006 / 002256 3 Advantageously, to determine the vertical component of the wind:

a1) the effective values ​​of a plurality of parameters of the aircraft are measured at said current position; and a2) said vertical component of the wind is calculated, taking into account said actual measured values.

In this case, advantageously, for an airplane - in step a1), we measure:

= using an inertial unit, the vertical speed Vz of the airplane with respect to the ground, the angle ~ of inclination of the wings of the airplane with respect to the horizontal, the attitude 0 of l the plane relative to the horizontal, and its pitch speed g;

= using an anemometric probe, the speed Vtas of the airplane in relation to the air mass in which this airplane is flying;

= using an angle of attack probe, the angle of attack (x of the airplane;

and = using a sideslip probe, the sideslip angle P of the airplane;

and - in step a2), the vertical component Wz of the wind is calculated, using the following expression:

Wz = Vz + Vtas. (cos ~ .cosO.cosp.sin [a + (q.2 / Vtas)] - sinO.cosp.cos [a + (q. ~ / Vtas)] + sinR.cosO.sin ~) in which ~ represents the algebraic distance between the angle of attack probe and the aircraft's center of gravity.

Moreover, advantageously, the level of severity of the vertical turbulence is determined, as a function of the difference in vertical load factor between a load factor at equilibrium for the aircraft and a load factor resulting from the vertical turbulence.

In this case, preferably, said level of severity corresponds CA 02622110 2008-03-11 WO 2007/042652 PCT / FR2006 / 002256 4 - to a first level, when said difference in vertical load factor is less than or equal to a first predetermined value;

at a second level, when said difference in vertical load factor is greater than said first predetermined value and less than a second predetermined value; and - at a third level, when said difference in vertical load factor is greater than or equal to said second predetermined value.

In a first variant embodiment, said level of severity of vertical turbulence is determined from two linear combinations of the vertical component of the wind and of its derivative, and, in a second variant embodiment, said level of severity is determined at from the calculation of two probabilities.

Furthermore, in a particular embodiment - said control order is calculated from a linear combination of the vertical component of the wind and its derivative; and / or - said activation conditions depend both on the level of severity of the vertical turbulence and on the difference between the value of said control command and a predetermined threshold value.

In a particular embodiment, for an airplane, the control command is transmitted to at least one of the following moving parts of the airplane: a spoiler and a aileron, and it is determined (and transmitted to an elevator of the aircraft) at least one auxiliary control command intended to compensate for the pitching moment generated by the control of said movable member.

The present invention also relates to a device for attenuating on an aircraft the effects of at least one vertical turbulence encountered by this aircraft, for example a transport aircraft, during a flight.

CA 02622110 2008-03-11 WO 2007/042652 PCT / FR2006 / 002256 According to the invention, said device is remarkable in that it comprises:

- at least one controllable movable member which is capable of acting on the lift of the aircraft;

5 - first means for determining a vertical component of the wind existing outside the aircraft at a current position of said aircraft;

second means for automatically determining, using this vertical component of the wind, a level of severity relating to vertical turbulence existing outside the aircraft at said current position;

- third means for automatically calculating, using said vertical component of the wind, at least one control order for said controllable movable member, said control order being such that it makes it possible to minimize the amplitude of the load factors generated on the aircraft by vertical turbulence; and fourth means for automatically checking whether activation conditions depending at least on said level of severity are achieved, and for automatically transmitting said control command to at least one actuator of said controllable movable member, when said activation conditions are fulfilled. .

The device according to the present invention therefore makes it possible to attenuate the amplitude of the vertical load factor generated by vertical turbulence, and this at any point of the aircraft.

It also makes it possible to reduce possible variations in altitude.

In addition, this device according to the invention has the advantage of being able to be installed on any type of aircraft (military, civilian, commercial) provided with at least one movable member (spoiler, aileron, etc.) of the type. any having an effect on lift.

CA 02622110 2008-03-11 WO 2007/042652 PCT / FR2006 / 002256 6 In a particular embodiment, said first means comprise:

a set of measurement elements for automatically measuring the effective values ​​of a plurality of parameters of the aircraft at said current position; and - a calculation means for automatically calculating said vertical component of the wind, taking into account said actual measured values.

Preferably, said set of measuring elements comprises at least one inertial unit, at least one anemometric probe and at least one angle of attack probe, as well as optionally at least one sideslip probe. The use of a sideslip probe makes it possible to increase the precision of the vertical component of the wind. Generally, the above measuring elements already exist on the aircraft, which makes it possible in particular to reduce the cost of the device according to the invention.

To further reduce the cost of said device, advantageously, said second and third means, as well as said calculation means, form part of an automatic piloting system of the aircraft.

The figures of the appended drawing will make it easy to understand how the invention can be implemented.

In these figures, identical references designate similar elements.

FIG. 1 is the block diagram of a device according to the invention.

FIG. 2 schematically shows a particular embodiment of a device according to the invention.

The device 1 in accordance with the invention and shown schematically in FIG. 1, is intended to attenuate on an aircraft not shown, for example a transport aircraft, the effects of at least one vertical turbulence encountered by this aircraft during flight.

It is known that a tur CA 02622110 2008-03-11 WO 2007/042652 PCT / FR2006 / 002256 7 bulence corresponds to an agitation of the air which is superimposed on the average movement of the air and which is constituted by disordered movements. , in continual transformation.

Turbulence occurs inside or in the vicinity of clouds (for example in a stormy cloud where vertical currents in opposite directions coexist).

There is also turbulence in clear skies, either near the ground, or especially at very high altitude near jet streams.

According to the invention, said device 1 comprises - at least one movable member 2 which is controllable and which is capable of acting on the lift of the aircraft - means 3 specified below, for determining a vertical component Wz of the wind which exists outside the aircraft at the current position of the latter;

means 4 for automatically determining, using the vertical component Wz of the wind received from said means 3, a level of severity making it possible to characterize the vertical turbulence existing outside the aircraft at said current arrangement; and - means 5 for, successively:

= automatically calculate, using the vertical component Wz of the wind received via a link 6, a control order for said movable member 2 which can be controlled.

This control order is such that it makes it possible to minimize the amplitude of the load factors which are generated on the aircraft by the vertical turbulence, as specified below;

= automatically check whether the activation conditions (which depend at least on said level of severity received via a link 7 of said means 4) are fulfilled; and = automatically transmit said calculated control command to a usual actuator 8 of said controllable movable member 2, by the inter CA 02622110 2008-03-11 WO 2007/042652 PCT / FR2006 / 002256 8 through a link 9, when said activation conditions are met and only in this case.

Thus, the device 1 according to the invention determines a level of severity of the vertical turbulence, in order to know whether it is necessary to implement actions to attenuate the effects of the vertical turbulence.

When such actions are necessary, said device 1 acts (via said movable member 2) on the total lift of the aircraft, which makes it possible to minimize the amplitude of the vertical load factor of the aircraft, and this everywhere in his cabin.

The device 1 according to the present invention thus makes it possible to combat in particular the variations in vertical load factor, which are generated by violent vertical turbulence and which are generally particularly brutal.

In a preferred embodiment, said means 3 intended to determine the vertical component Wz of the wind, comprise:

a measurement unit 10 specified below, for measuring the effective value of a plurality of parameters of the aircraft at said current position; and - a calculation means 11 which is connected via a link 12 to said measurement unit 10 and which is formed so as to calculate said vertical component Wz of the wind, taking into account the actual values ​​measured by said unit measuring 10.

To this end, said measuring unit 10 comprises a plurality of measuring elements or sensors C1, C2, ..., Cn intended to measure the effective values ​​of said aforementioned parameters of the aircraft.

Said calculation means 11 is connected via a link 13 to said means 4 and, via link 6, to said means 5.

In a particular embodiment, said means 4 and 5 and said calculation means 11 are integrated into a central unit 15 which forms CA 02622110 2008-03-11 WO 2007/042652 PCT / FR2006 / 002256 9 for example part of a the usual automatic piloting system of the aircraft.

As such an automatic piloting system generally already exists on the aircraft, this particular embodiment makes it possible to reduce the cost of the device 1 in accordance with the invention and to simplify its implementation.

In a particular embodiment, said means 5 determine the level of severity of the vertical turbulence, as a function of the difference in vertical load factor between a load factor existing in equilibrium on the aircraft and a load factor existing in response to vertical turbulence.

In this case, the level of severity corresponds - to a first level (called for example level 0), when said difference in vertical load factor is less than or equal to a first predetermined value, for example 0.3 g, g corresponding to the value of the acceleration created on the earth's surface by the force of gravity;

- at a second level (called for example level 1), when said difference in vertical load factor is greater than said first predetermined value (0.3 g for example) and is less than a second predetermined value, for example 0.5 g; and - at a third level (called for example level 2), when said difference in vertical load factor is greater than or equal to said second predetermined value (0.5 g for example).

In a first variant embodiment, said means 4 determine said level of severity of vertical turbulence from two linear combinations of the vertical component Wz of the wind and its derivative.

The coefficients of such a linear combination are optimized so that the levels are best recognized by the algorithm.

If one of these combinations exceeds a first predetermined threshold, level 1 is obtained, and if the other exceeds a second predetermined threshold, level 2 is obtained.

Level 2 has priority over level 1.

CA 02622110 2008-03-11 WO 2007/042652 PCT / FR2006 / 002256 In addition, in a second variant embodiment, said means 4 determine said level of severity from the calculation of two probabilities, namely on the one hand the probability to experience vertical load factor deviations (within a predetermined period of time to come, for example in one second) of more than a first predetermined value, for example of more than 0.3 g, and on the other hand the probability of undergoing vertical load factor deviations (during this predetermined period to come) of more than a second predetermined value, for example of more than 0.5 g.

These two probabilities are calculated from the vertical component Wz of the wind received from the means 3, from the angle of incidence α of the aircraft and from the pitch speed g of the aircraft.

If the probability associated with deviations of 0.3 g exceeds a predetermined threshold, level 1 is obtained.

If the probability associated with deviations of 0.5 g exceeds another predetermined threshold, level 2 is obtained.

The probability formulas are given from the learning of neural networks.

Level 2 has priority over level 1.

In addition, in a particular embodiment, said means 5 calculate said control order for the movable member 2, from a linear combination of the vertical component Wz of the wind and its derivative.

In addition, said activation conditions taken into account by means 5 depend on the level of severity of vertical turbulence, received from said means 4 via link 7, as well as on the value of said control command, which is compared to a threshold value.

In order for the system to be activated (that is to say for the activation conditions to be fulfilled), it is necessary that, in the above-mentioned example, the level of severity is at least at level 1 and the command order exceeds a predetermined threshold value.

Then, if the order order remains below a predetermined value, for a predetermined time, without the appearance of CA 02622110 2008-03-11 WO 2007/042652 PCT / FR2006 / 002256 11 level 2, the order order is canceled . The order is also canceled if the severity level goes from level 2 to level 1, with a derivative of the incidence which is negative.

In a preferred embodiment shown in FIG. 2, which is applied to an airplane, said measurement unit 10 comprises as sensors C1, C2, C3 and C4 which are respectively connected via links 12A, 12B, 12C and 12D audit calculation means 1 1:

a usual angle of attack probe Cl, for measuring the angle of incidence a of the airplane;

a usual C2 sideslip probe, for measuring the sideslip angle R of the airplane;

- a usual C3 inertial unit, to measure the vertical speed Vz of the airplane with respect to the ground, the angle of inclination of the wings of the airplane with respect to the horizontal, the attitude 0 of the airplane relative to the horizontal, and its pitching speed g; and - a standard anemometric probe C4, for measuring the speed Vtas of the airplane with respect to the mass of air in which this airplane is operating.

In this example, the calculation means 11 calculates the vertical component Wz of the wind, using the following expression Wz = Vz + Vtas. (cos ~ .cosA.cosR.sin [a + (q..e / Vtas)] - sinA.cos (3.cos [a + (q..F? / Vtas)] + sinP.cosO.sin ~) in which ~ represents the algebraic distance between the angle of attack probe Cl and the center of gravity of the airplane.

In addition, in this example of FIG. 2, the incidence probe C1 is connected via a link 16A to the means 4 to provide them with the angle of incidence a, and the inertial unit C3 is connected. via a link 16C to said means 4 to provide them with the pitch speed q.

This angle of incidence a and this pitch speed g can be used by the means 4 to determine the level of severity CA 02622110 2008-03-11 WO 2007/042652 PCT / FR2006 / 002256 12 of the vertical turbulence, in accordance with the second variant of the aforementioned embodiment.

In addition, in the example of Figure 2, the device 1 according to the invention comprises as movable member:

- at least one customary spoiler 2A, which is mounted on a wing 17 of the aircraft and which is associated with a standard actuation means 8A connected by means of a link 9A to said means 5; and - at least one usual fin 2B, which is also mounted on a wing 17 and which is associated with a usual actuator 8B connected by means of a link 9B to said means 5.

As indicated above, the control orders for the spoiler (s) 2A and the aileron (s) 2B are obtained from a linear combination of the vertical component Wz of the wind and its derivative.

In addition, in a particular embodiment, said means 5 further determine an auxiliary control command, and they transmit this auxiliary control command, by means of a link 18, to a usual actuator 19 of a control surface. of usual depth 20 which is mounted on a horizontal stabilizer 21 of the aircraft.

This auxiliary control command is intended to compensate for the pitch moment which is generated by the control (according to the invention) of the spoiler (s) 2A and of the aileron (s) 2B.

Said auxiliary control order is proportional to the control orders of the spoiler (s) 2A and of the aileron (s) 2B, according to a gain calculated from the case of flight (weight, power plant, speed and altitude of the airplane).

The different orders are phased.

Phasing consists in making equal the time necessary for each mobile element (mobile device 2A, 2B; elevator 20) to reach the setpoint value.

This time is chosen like that of the slowest moving element (movable member 2A, 2B; elevator 20) WO 2007/042652 PCT / FR2006 / 002256 13.

Of course, the control orders determined in accordance with the present invention are superimposed on the orders supplied in the usual way by other piloting members of the aircraft, before being transmitted to the actuators 8A, 8B, 19 of the mobile elements (member mobile 2A, 2B; elevator 20).

Thus, the device 1 in accordance with the invention is equally applicable to a manual aircraft flight control system as to an automatic aircraft flight control system.

The device 1 according to the present invention therefore makes it possible to attenuate the amplitude of the vertical load factor generated by vertical turbulence, and this at any point of the aircraft.

It also makes it possible to reduce possible variations in altitude.

In addition, this device 1 according to the invention has the advantage of being able to be installed on any type of aircraft (military, civilian, commercial) provided with at least one movable member of any type (spoiler 2A, aileron 2B). having an effect on the lift of the aircraft.

In the context of the present invention, the aforementioned method of calculating the vertical component Wz of the wind can be supplemented or replaced by a specific probe or by information external to the systems of the aircraft, for example communications of meteorological readings received from the ground or another aircraft.