WO2018167197A1

WO2018167197A1 - Method for optimizing the flight attitude of a drone, and associated electronic device, electronic apparatus and drone

Info

Publication number: WO2018167197A1
Application number: PCT/EP2018/056487
Authority: WO
Inventors: Henri Seydoux; Mathieu Babel
Original assignee: Parrot Drones
Priority date: 2017-03-16
Filing date: 2018-03-15
Publication date: 2018-09-20
Also published as: FR3063911A1

Abstract

The method for optimizing the flight attitude of a rotary-wing drone capable of moving through the air by means of at least one rotor operated by at least one motor is implemented by an electronic optimization device. This method comprises, during the flight of the drone, at least once determining (172, 176, 184, 186) a maximum angle (θ max,t) of inclination of the drone as a function of an item of information (ls) indicative of the level of saturation of at least one motor of the drone.

Description

Method for optimizing the flight inclination of a drone, electronic device, electronic device and associated drone

The present invention relates to a method for optimizing the flight inclination of a rotary-wing drone adapted to move in the air by means of at least one rotor actuated by at least one engine, the method being implemented implemented by an electronic optimization device.

The invention also relates to a computer program comprising software instructions which, when executed by a computer, implement such a method of optimizing the flight inclination of a drone.

The invention also relates to an electronic device for optimizing the flight inclination of a rotary wing drone.

The invention also relates to an electronic device for controlling the engine (s) of a rotary wing drone comprising such an electronic device for optimizing the flight inclination.

The invention also relates to a rotary wing drone adapted to move in the air by means of at least one rotor actuated by at least one engine comprising at least one electronic device for optimizing the flight inclination of the drone of the aircraft. aforementioned type.

The invention relates to the field of drones, that is to say remotely controlled motorized devices. The invention is particularly applicable to rotary-wing drones, such as helicopters, or drones with several rotating wings such as quadricopters or other over-powered drones such as hexacopters or optocopters, etc.

Rotary wing drones, for example, quadricopter type, are able to hold a fixed point and evolve as slowly as desired, which makes them much easier to fly even by inexperienced users.

However such drones do not allow to maintain a significant inclination (i.e. for example greater than 30 ° in roll and / or pitch) in flight and are able to lose altitude once a predetermined threshold of horizontal velocity reached.

In fact, as the horizontal flight speed of the drone increases, the drone, flying with an inclination with respect to the horizon, is subject to modifications of operation which require a surplus of power to the drone .

Among these operating modifications appearing during the increase in the horizontal flight speed of the inclined flying drone, are notably: the reduction in the efficiency of one or more propellers, and consequently a reduction in the thrust of one or more propellers corresponding to the increase in airspeed,

- the generation of a deportation by the body of the inclined drone, deportation that must be countered in addition to the weight,

the appearance of a tilting torque on the propeller (s) requiring, in compensation, a constant injection by the drone of a trim control to maintain its angle of inclination,

- the appearance of a wind vane effect according to the wind direction requiring the drone the application of a heading command.

- etc.

Consequently, for a drone accelerating with a constant inclination angle, the engines will arrive at saturation once a certain horizontal speed has been reached corresponding to the predetermined horizontal speed threshold.

One of the aims of the invention is then to propose a method of optimizing the flight inclination of a drone allowing an improvement in the agility of the drone while ensuring that the flying drone inclined with a speed greater than a predetermined speed threshold will not descend inexorably to the ground.

For this purpose, the object of the invention is a method of optimizing the flight inclination of a rotary wing drone adapted to move in the air by means of at least one rotor powered by at least one engine. , the method being implemented by an electronic optimization device the method comprising, during the flight of the drone, at least once, the determination of a maximum angle of inclination of the drone according to information representative of the saturation state of at least one engine of the drone.

The method of optimizing the flight inclination of a rotary wing drone according to the invention taking into account the saturation state of the engine (s) of the drone then makes it possible to play in real time on the reference of maximum angle of inclination not to be exceeded which simultaneously relieves the engine power requirements and therefore allows engine desaturation.

In other words, a saturation of the maximum angle of inclination is implemented to simultaneously allow engine desaturation.

Thus, the method according to the invention corresponds to a servo control of the agility of the drone as a function of the engine saturation state.

The flight angle of the drone is optimized automatically regardless of the saturation state of his or her engines. Subsequently, the term "angle of inclination" means the angle formed between the plane comprising the body of the drone (fuselage) and the horizon. In other words, such an angle of inclination is associated with a pair of angles of roll and pitch. In addition, "maximum angle of inclination of the drone" means the tilt angle reference that the drone is not allowed to exceed once this determined angle.

According to other advantageous aspects of the invention, the method for optimizing the flight inclination of a drone comprises one or more of the following characteristics, taken separately or in any technically possible combination:

the implementation of the determination of the maximum angle of flight inclination of the drone as a function of information representative of the saturation state of said at least one engine is conditioned by the value of the horizontal displacement speed of the drone;

the method comprises comparing the horizontal speed of movement of the drone with a predetermined speed threshold;

when the horizontal speed of movement of the drone is below the predetermined speed threshold, the maximum angle of flight inclination of the drone is equal to a predetermined maximum inclination value, and when the horizontal speed of movement of the drone is greater than at the predetermined speed threshold, the determination of the maximum angle of flight inclination of the drone as a function of information representative of the saturation state of said at least one engine is implemented;

the determination of the maximum angle of flight inclination of the drone as a function of information representative of the saturation state of said at least one engine comprises:

at the first engine saturation detected during the flight of the drone: the measurement of the angle of inclination of the first engine saturation; storing the tilt angle value of the first motor saturation; the definition of the maximum angle of flight inclination of the drone as equal to the tilt angle value of the first engine saturation, then

at least one iteration of the following steps as long as the horizontal speed of movement of the drone is greater than the predetermined threshold: when the value of the representative information represents the saturation of at least one engine, the maximum angle of flight inclination the drone is decreased by the angular velocity of motor saturation by remaining greater than or equal to a predetermined minimum inclination value; when the value of the representative information represents the absence of engine saturation, the maximum angle of flight inclination of the drone is increased by the speed angular motor desaturation remaining less than or equal to the predetermined maximum inclination value; and

the information representative of the saturation state of at least one engine of the drone is Boolean.

The invention also relates to a computer program comprising software instructions which, when executed by a computer, implement a method as defined above.

The invention also relates to an electronic device for optimizing the flight inclination of a rotary wing drone adapted to move in the air by means of at least one rotor actuated by at least one engine, the electronic device comprising at least one determination module configured to determine a maximum angle of inclination of the drone based on information representative of the saturation state of at least one engine of the drone.

The invention also relates to an electronic device for controlling the engine (s) of a rotary-wing drone adapted to move in the air by means of at least one rotor actuated by at least one engine, in wherein the electronic apparatus comprises a control unit configured to separately control each engine of the drone, by control passage in the mark of said engine and by automatic management of the engine saturation of said engine and the electronic device for optimizing the inclination of flight as defined above.

The invention also relates to a rotary-wing drone capable of moving in the air by means of at least one rotor actuated by at least one engine, the drone comprising at least one electronic device for optimizing the inclination flight of the drone as defined above.

These features and advantages of the invention will become apparent on reading the description which follows, given solely by way of nonlimiting example, and with reference to the appended drawings, in which:

- Figure 1 is a perspective view of an electronic guidance system of a drone according to the invention, comprising a rotary wing drone adapted to evolve in the air under the control of remote remote control equipment;

FIG. 2 is a block diagram of the various servo control and steering control elements of the drone;

- Figure 3 is a partial schematic representation of the modules constituting the electronic device for optimizing the flight inclination according to the invention corresponding to a control stage of the motors operating the rotor (s) of the drone; FIG. 4 is a flowchart of a method for determining the angle of inclination of the drone according to the invention,

FIG. 5 is a schematic representation of the geometrical parametrization of a drone engine

FIG. 6 is a flow chart of an engine control method according to the invention.

In the remainder of the description, the expression "substantially equal to" is understood as a relationship of equality at plus or minus 10%, that is to say with a variation of at most 10%, preferably again as a relationship of equality at plus or minus 5%, that is to say with a variation of at most 5%.

In FIG. 1, an electronic system for guiding a drone makes it possible, by means of an electronic display system 10, for a user 12 to optimize the guidance of a drone 14.

The drone 14 is a motorized flying machine remote control, including via a lever 16 allowing the user 12 to enter his flight instructions.

The drone 14, that is to say an unmanned aircraft on board, comprises an image sensor 18 configured to take an image of a scene comprising a plurality of objects. Such a drone 14 is for example a rotary wing drone comprising at least one rotor 20 (or propeller) actuated by at least one engine. In FIG. 1, the drone 14 comprises a plurality of rotors 20, and is then called a multirotor drone. The number of rotors 20 is in particular four in this example, and the drone 14 is then a quadrotor or quadrocopter drone.

The drone 14 is also provided with a transmission module 22 for transmitting, preferably by radio waves, to an electronic device, such as the reception module, not shown, of the electronic display system 10, the transmission module. reception, not shown, of the lever 16 or the receiving module of the digital multimedia touch-screen tablet 23 mounted on the lever 16, not shown, the image or images acquired by the image sensor 18.

An electronic display system 10 allows the user 12 to view images, in particular images of the video received from the rotary wing drone 14.

The electronic display system 10 comprises an electronic device, for example, a smartphone, provided with a display screen, and a headset 24 comprising a support for receiving the electronic device, a surface against the face of the user 12, facing his eyes, and two optical devices disposed between the receiving support and the support surface. The helmet 24 further comprises a holding strap 26 for holding the helmet 24 on the head of the user 12.

The electronic device is removable relative to the helmet 24 or integrated into the helmet 24.

The electronic display system 10 is, for example, connected to the lever 16 via a data link, not shown, the data link being a radio link or a wired link.

In the example of FIG. 1, the electronic display system 10 further comprises a reception module, not shown, configured to receive at least one image from the rotary wing drone 14, the transmission of the image being preferably carried out by radio waves.

The viewing system 10 is for example a virtual reality display system, that is to say a system allowing the user 12 to visualize an image in his visual field, with a field of vision angle, also called Field Of View (FOV), having a large value, typically greater than 90 °, preferably greater than or equal to 100 °, to provide immersive vision (also called FPV vision). English First Person View) for the user 12.

The lever 16 is known per se, and makes it possible, for example, to control the rotary wing drone 14. The lever 16 comprises two grip handles 28, each being intended to be grasped by a respective hand of the user 12, a plurality of control members, here comprising two joysticks 30, each arranged in proximity to a respective handle 28 and being intended to be actuated by the user 12, preferably by an inch respective.

The controller 16 also includes a radio antenna 32 and a radio transceiver, not shown, for exchanging radio wave data with the rotary wing drone 14, both uplink and downlink.

In addition, or as an alternative to the visualization system 10, the multimedia digital tablet 23 touch screen is mounted on the lever 16 to assist the user 12 during the piloting of the rotary wing drone 14.

The controller 16 is configured to transmit the user's control instructions 124 to an autopilot integrated into the rotary wing drone, an exemplary functional block diagram of which is shown in FIG.

The electronic guidance system of the drone described above, and notably comprising a visualization system in virtual reality, is given by way of example, the invention can be implemented with other types of drone guidance systems.

The piloting of the drone 14 is to change it by:

a) rotation about a yaw axis 34, to pivot to the right or to the left the main axis of the drone

b) rotation about a pitch axis 36, to move it forward or backward

c) rotation about a roll axis 38, to shift it to the right or to the left; and

d) translation downwards or upwards by changing the speed of the gasses so as to respectively reduce or increase the altitude of the drone.

FIG. 2 is a block diagram of the various servo control and steering control elements of the drone 14, as well as correction of the movements of the image according to the technique of the invention.

It will be noted that, although these diagrams are presented in the form of interconnected circuits, the implementation of the various functions is essentially software, this representation having only an illustrative character.

In general, as illustrated in FIG. 2, the control system involves several nested loops for controlling the horizontal speed, the angular speed of the attitude of the drone 14 and altitude variations, automatically or under control of the aircraft. 'user.

The most central loop is the angular velocity control loop 100, which uses, on the one hand, the signals supplied by gyrometers 102 and, on the other hand, a reference consisting of angular velocity instructions 104. This information is applied in input of a stage 106 for correcting the angular velocity, which itself controls a stage (ie electronic apparatus) 108 for controlling the motors 1 10 so as to separately control the speed of the various motors to correct the angular velocity of the drone 14 by the combined action of the rotors driven by these motors. The electronic control device 108 of the motors 1 10 according to the invention is described below in more detail in relation to FIG.

The angular velocity control loop 100 is embedded in a loop

1 12 of attitude control, which operates from the indications provided by an inertial unit 1 14 including gyrometers 102, accelerometers 1 16 and a stage 1 18 which produces an estimate of the actual attitude of the drone 14. The data from these sensors are applied to the stage 1 18 which produces an estimate of the actual attitude of the drone 14, applied to an attitude correction stage 120. This stage 120 compares the real attitude of the drone 14 to angle commands generated by a circuit 122 from commands directly applied by the user 124 and / or from data generated internally by the autopilot of the drone 14 via the circuit 126 horizontal speed correction V _H (or horizontal speed of movement of the drone). The possibly corrected instructions applied to the circuit 120 and compared to the actual attitude of the drone 14 are transmitted by the circuit 120 to the circuit 104 to control the motors appropriately.

Finally, a horizontal speed control loop 130 includes a vertical video camera 132 and a telemetric sensor 134 acting as an altimeter. A circuit 136 processes the images produced by the vertical camera 132, in combination with the signals of the accelerometer 1 14 and the attitude estimation circuit 1 18, to produce data for obtaining an estimate of the speeds. horizontally along the two axes of pitch and roll of the drone 14, by means of a circuit 138. The estimated horizontal speeds are corrected by the estimate of vertical speed given by a circuit 140 and by an estimate of the value of the altitude, given by the circuit 142 from the information of the telemetric sensor 134.

For the control of the vertical displacements of the drone 14, the user 124 applies commands to a circuit for calculating altitude setpoints 144, which instructions are applied to a calculation circuit of ascending speed instructions V _z 146 via the control circuit. altitude correction 148 receiving the estimated altitude value given by the circuit 142. The calculated climbing speed V _z is applied to a circuit 150 which compares this set speed with the corresponding speed estimated by the circuit 140 and modifies accordingly the control data of the motors (electronic apparatus 108) by increasing or decreasing the speed of rotation simultaneously on all the engines so as to minimize the difference between the ascending speed of reference and measured rate of climb.

As regards more specifically the implementation of the invention, the electronic device 108 for controlling the motors is moreover also connected, according to the example of FIG. 2, to a module 152 configured to determine the speed of rotation. engines necessary to maintain the drone 14 fixed point (English Feed Forward, ie the drone 14 is maintained at constant altitude while maintaining its course, and to do this it is necessary to determine the speed of rotation of the engines for counter the weight of the drone 14).

Optionally, a BLDC (Brushless DC electric motor) power supply module 154 is connected firstly to the motor setpoint Ω of the control stage 108 and supplies voltage V and current I to the motors 10. depending on this output setpoint. According to the present invention, the motors are configured to be connected in a feedback connection to the control stage 108, and optionally to the BLDC power module 154.

In relation with FIG. 3, according to the electronic control device 108 for controlling the motors 1 10, actuating the rotor (s) 20 of the drone 14, comprises an electronic device for optimizing the flight inclination according to the invention. .

In other words, with respect to an existing electronic control apparatus for drone engines 14, the electronic control device 108 for controlling the engines is suitable for implementing the method of optimizing the flight inclination according to the invention. In other words, the electronic device 108 for controlling the motors actuating the rotor (s) of the drone 14 is also able to control in real time the tilt reference of the drone 14 (corresponding to the maximum angle d inclination of the drone) allowed, if necessary, to allow engine desaturation.

In the example of FIG. 3, the electronic device 108 for controlling the motors actuating the rotor (s) of the drone 14 comprises an information processing unit 156, formed for example by a memory 158 and by a processor 160 associated with the memory 158.

According to one embodiment of the invention, the memory 158 is configured to at least store according to the present invention a set of predetermined data, for example listed in a reference file, comprising at least:

a threshold S _V H with a predetermined horizontal speed, for example 3m / s,

a maximum value Val _ma x of predetermined inclination, for example 35 °,

a minimum value Val _min of predetermined inclination, for example 20 °,

an angular saturation speed V _sat , for example 5 s,

an angular speed of engine desaturation V _Dsa t, for example 27s.

Furthermore, during flight, the memory 58 is also configured to temporarily store the maximum tilt angle value 6 _{max t} (ie tilt angle reference) determined at a time t in the course of least one iteration of the method according to the present invention to restore it to a next iteration as well as the angle Q _c inclination of the first motor saturation.

In other words, according to this example, the flight angle of flight of the drone will be able to vary between 20 and 35 °.

The electronic engine control apparatus 108 according to the invention further comprises a control unit 162 (also known as Mix Mixed RPMs) configured to separately control each engine of the engine. drone 14, by control passage in the engine mark and by management of the engine saturations.

Furthermore, the electronic engine control device 108 also comprises an electronic device 164 for optimizing the flight inclination according to the invention. Such an electronic flight tilt optimization device 164 is formed, for example, on the one hand by a module 166 for comparing the horizontal speed V _H of displacement of the drone with a predetermined speed threshold S _V H stored in the memory 158, and on the other hand by a determination module 168 configured to determine a maximum angle of inclination of the drone 14 as a function of information 1 _s representative of the saturation state of at least one engine of the drone 14.

In the example of FIG. 3, the control unit 162, the horizontal velocity comparison module 166 V _H and the maximum inclination angle determination module 168 of the electronic optimization device 164 of FIG. flight inclination, are each made in the form of software executable by the processor 160. The memory 158 of the information processing unit 156 is then able to store a control software configured to separately control each engine of the drone, a comparison software configured to compare the horizontal speed V _H of movement of the drone to a threshold S _V H of predetermined horizontal speed, a determination software configured to determine a maximum angle of inclination of the drone 14 according to a piece of information; _s representative of the saturation state of at least one engine of the drone 14. The processor 160 of the information processing unit 156 is then able to execute the control software, the comparison software and the determination software in parallel or successively.

In a variant that is not shown, the control unit 162, the horizontal speed comparison module 166 V _H and the maximum inclination angle determination module 168 of the electronic flight tilt optimization device 164 are each made in the form of a programmable logic component, such as an FPGA (Field Programmable Gathe Array), or in the form of a dedicated integrated circuit, such as an ASIC (English Applications Specifies) Integrated Circuit).

The operation of the electronic control device 108 for controlling the engine (s) of the drone 14 will now be explained with reference to FIGS. 4 to 6.

In particular, FIG. 4 represents a flowchart of the method of optimizing the flight inclination of the drone 14 implemented by the electronic flight tilt optimization device 164 according to the invention. During a step 170, the electronic device 164 for optimizing the flight inclination begins, at a time t during the flight of the drone, by comparing the horizontal speed V _H (which it receives, for example, from the circuit 126). horizontal speed correction device V _H shown in FIG. 2) at a predetermined horizontal speed threshold S _V H stored in the memory 158 of the electronic device 108.

When, according to the result of this comparison 170, the horizontal speed V _H remains lower than the threshold S _V H of horizontal speed, then, in a step 172, the value of the maximum angle of flight inclination of the drone 14 is set equal to a maximum value A predetermined _maximum inclination value, for example 35 ° stored in the memory 158 of the electronic apparatus 108. In other words when V _H <S _V H, _max e = _max Val

On the other hand, when the horizontal velocity V _H is greater than the threshold S _V H of horizontal velocity, a step 174 of determining the value, at this instant t, of information 1 _s representative of the saturation state of at minus a motor 1 10 of the drone 14 received by means of the link 155, directly from the motor or motors 1 10, or indirectly via the power supply module 154 BLDC is implemented by the electronic device 164.

Thus, the implementation 174 of the determination of the value of the information 1 _s representative of the state of saturation of the engine (s) 1 10 of the drone 14 is, according to the example of Figure 4, packaged by the value of the horizontal movement speed V _H of the drone (ie it is implemented only in the presence of a high horizontal speed because higher than the threshold S _V H of horizontal velocity).

For example, the information l _s representative of the saturation state of at least one engine 1 10 of the drone 14 is boolean, for example, l _s = 0 represents the presence of a saturation of at least one engine while that l _s = 1 represents the absence of motor saturation.

When the value of the information l _s represents the absence of engine saturation (ie for example l _s = 1), according to a step 176, the maximum angle of inclination 6 _{max t} of flight of the drone is increased by the speed angular motor desaturation remaining less than or equal to the predetermined maximum inclination value Val _max .

In other words, as e _max <Val _max Q _max Q _max = _ + V _Dsat,

with Qmax, the angle reference stored in memory 158 at a previous iteration. The angle reference is therefore clipped (from the English clamping) by the maximum predetermined inclination value Val _max .

When the value of the information 1 _s represents on the contrary the saturation of at least one motor (ie for example l _s = 0), according to a step 178, the electronic device First, it detects whether the saturation detected is the first saturation detected during the flight in question of the drone 14.

If this is the case, the instant t is for example stored (not shown) in the memory 158 as the instant t ₀ of the first saturation.

Then, in the presence of this first motor saturation, the electronic device

164 measurement, or receives the measurement by another steering member of the drone, the current inclination angle Q _c of the drone 14 also called tilt angle of the first engine saturation. Such an inclination angle Q _c of the first motor saturation is necessarily less than or equal to the maximum predetermined inclination value Val _max .

According to step 182, the inclination angle Q _c of the first motor saturation is stored in the memory 158 and parallel or successively, according to a step 184, the electronic device 164 defines the maximum angle of inclination 6 _{max t} as equal to this angle angle Q _c of the first motor saturation (ie 6 _{max t} = 0 _C ).

If the saturation detected by the electronic device 164 is subsequent to the first saturation (ie t> t ₀ ), then according to a step 186, the maximum angle of inclination ^e max, t of flight of the drone is decreased by the angular velocity saturation V _sat remaining greater than or equal to the predetermined minimum inclination value Val _min .

In other words, as long as e _max ≥ Val _min , Q _max = Q _max _ - V _sat ,

with Q _m ax, t \ ^'has reference angle stored in the memory 158 in a previous iteration. The reference angle is clipped (English clamping) by the minimum value predetermined inclination Val _min .Thus, steps 174-186 taking into account the information representative of the _s engine state saturation drone 14 offers the possibility of implementing a saturation of the inclination to desaturate the engine (s) 1 10.

Advantageously, the initial step of comparing 170 of the horizontal velocity V _H with the threshold S _V H of horizontal velocity makes it possible in particular to treat the particular case where the drone 14 flies in the presence of a strong wind.

Indeed, in the case where the drone 14 flies in fixed point but undergoes a strong wind (ie a clean wind to saturate the engines even as the horizontal speed V _H of the drone is below the threshold S _V H horizontal speed) , activating the saturation of the angles triggered according to step 174 would cause the drone to recover, which would then drift with the wind.

It is then preferable not to implement step 174 of the value of the information l _s and the following steps 176 to 186 which saturate the maximum angle of inclination to allow engine desaturation. In other words, at a low horizontal velocity V _H of the drone 14 (V _H <S _V H) the existing behavior of the state of the art, the drone flying in a fixed point, is preserved, such behavior is not risky in this respect. specific case.

Thus, by way of example, according to the invention at the beginning of the flight, the maximum angle of inclination is at 35 °. The drone can therefore accelerate responsively in terms of agility. At a time t equal for example to 191 s, at least one of the motors is in saturation and the maximum angle will be reduced according to step 186. Thereafter, it starts to increase when the saturation disappears and so on. It therefore oscillates permanently, in an envelope of some degrees, for example about 15 °, framed between Val _min and Val _max .

From the point of view of the user 12, such a behavior of the drone 14 is obviously not detectable because the amplitude is too low for the user 12 to guess, especially since the drone 14 is at high speed during this oscillation leading to engine desaturation.

Moreover, according to this example, such behavior has the effect that the altitude loss of the drone is limited in relation to its altitude reference point fixed between the beginning and the end of the engine desaturation.

Thus, according to the present invention, a stabilization of the horizontal speed is obtained, which allows the drone correlatively to be at the boundary of the engine saturation.

In connection with FIGS. 5 and 6, the operation of the control unit 162 will now be explained.

The control unit 162 is notably configured to convert the commands generated by:

the stage 106 for correcting the angular velocity V _H ,

the circuit 150 for correcting the ascending speed V _z , and

the module 152 configured to determine the rotational speed of the motor or motors necessary to maintain the drone 14 in a fixed point,

in motor reference Ω actually transmitted to motors 1 10.

Considering an example where the drone 14 is a quadrocopter provided with four rotors 20 (i.e. propellers) actuated respectively by four motors, the engine setpoint

r ^w n

Ω corresponds in particular to a vector Ω = with Wjla rotation speed of the motor

of index / ^' . According to the present invention, the motor output setpoint Ω is obtained by transforming the acceleration setpoints according to the thrust axis of the drone and angular accelerations expressed in the form of a control vector: = g (fi) with g a vector function obtained from

equations of the dynamics and parameters of the drone and p, q, r the angular velocities of roll, pitch and yaw of the drone 14.

The first benefit to generate type commands ^e j is to get a generic controller 108. Indeed, it can be considered as a first approach that for a given angle error, generic controller 08 is able to send the same set of angular acceleration to compensate for whatever drone to control.

More specifically, in connection with FIG. 5, the control unit 1 62 is configured firstly to implement a control passage in the reference of each index motor / ^' .

We denote by x ,, y ,, z ,, the Cartesian coordinates of the motor 1 1 0 index /, _t and β the angles defining the orientation of the motor with respect to the axis 1 88 of roll and the axis 190 pitch of the engine 1 10 index / ^' .

Moreover, we denote m the mass of the drone, J its inertia matrix and T, = {T _t ^x , T? , T?) And Γ, = (Γ, Γ?, Γ *) the thrusts and torques generated by the index motor / ^' .

So by projecting on the different aces one obtains:

T _t ^x = cosCa ^ cosGS II ^ II, 7 = sinfe) cos () ll ^ ll, Tf = sin (fii) \\ Ti \\,

Γ = cosC ^ cosGS II / 11, Γ = sinCa cos ^ II i ll. ^ =

To transform the acceleration setpoints according to the thrust axis of the drone and angular accelerations into motor output setpoint Ω the relation Ω = g ^ x ^^ is applied where g ^-1 the mixing function is obtained from the equations of the dynamics and parameters of the drone known in themselves.

Furthermore, in connection with FIG. 6, the control unit 1 62 is also configured to saturate the commands received from:

the stage 106 for correcting the angular velocity V _H ,

the circuit 150 for correcting the ascending speed V _z , and

the module 1 52 configured to determine the rotational speed of the motor or motors necessary to maintain the drone 14 in a fixed point.

According to the invention, the commands are saturated so as to maintain them in a predetermined interval while maintaining their coherence. To do this, the orders received are prioritized according to an order of priority, namely from the highest priority to the lowest priority:

the altitude command delivered by the module 152 necessary to counter the weight of the drone in a fixed point,

- pitch control, followed by roll control,

- the yaw control, and

- the acceleration control to reach an altitude reference.

In other words, we consider that above all, the drone must maintain its altitude. For stability reasons, he must then hold his trim angles. The pitch has priority over the roll because the drone 14 admits a priori the plane containing the roll axis 38 as the plane of symmetry, but not necessarily the plane containing the pitch axis 36. Then, the lace has priority before the altitude because one arbitrarily according to an embodiment it is preferred to hold its course that does not reach its altitude reference.

Without such an order of priority imposed between the commands according to the invention, the motors 1 10 would achieve their saturation themselves.

However, when a motor saturates, it has no notion of priority of the commands and it is a combination of the commands which is modified, and the drone 14 would turn over because the commands in roll and pitch have a sensitivity and a time higher response rates than other commands.

So that the stability of the drone is maintained even when the engine power is not sufficient, the orders are classified according to the invention in order of priority and added in this order. According to the needs and limitations of the engines, the least priority order (s) are reduced in order not to saturate.

The control saturation process implemented by the control unit

162 is illustrated in Figure 6.

In a first step 192, an indicator (of the English flag) of saturation is incremented. Then during a step 194, the control unit 162 verifies that the commands of each motor are within a predetermined saturation interval.

If so, according to a step 196 these saturation control after passage in the engine mark as described above are transmitted in the form of motor setpoint to the engines 1 10.

In the opposite case, according to a step 198, the control unit 162 verifies that the total motor control (ie after adding the orders classified in the aforementioned order) motor by motor is in a predetermined saturation interval. In the affirmative for a given engine of index i, the control unit 162, according to a step 200 passes to the verification 198 of the following engine, otherwise in a step 202, the command of index j among the five commands of altitude delivered by the module 152, pitch, roll, yaw, and acceleration to reach an altitude reference are checked to determine whether or not the command considered is responsible for saturation.

In the negative, according to a step 204, the next motor is switched on, then according to a step 206, it is verified that all the motors have been thus tested. If so, according to a step 208, the value of the indicator is incremented and the next order is placed in the aforementioned order of priority. On the other hand, if not, the method is repeated in step 198 for checking the next engine.

On the other hand, if the result of step 202 of checking the index command j is negative, according to a step 212, the indicator is incremented, then according to a step 214, the control unit 162 tests the setting. zero of the command considered to evaluate whether such a zeroing changes the saturation state of the engine.

If so, this command is effectively set to zero according to a step 216, in the negative according to a step 218 this control is reduced by a predetermined value.

The method of optimizing the flight inclination of a drone as illustrated in FIG. 4 makes it possible to add a saturation layer above altitude, the task of which will be to reduce the angle references of way to lean and slow down until saturation disappears. Note that the angle control remains a priority over the altitude in the electronic control device 108 of the engines 1 10 according to the invention. It is only the angle reference that is impacted.

The method of optimizing the flight inclination of a drone also makes it possible to eliminate altitude losses during high-speed movements and thus makes it possible to increase / decrease in real time and automatically the maximum angle of flight. tilt 14 to have a more nervous steering at low speed while ensuring that the drone 14 will not descend inexorably to the ground at high speed.

Claims

1. - Method for optimizing the flight inclination of a rotary wing drone (14) adapted to move in the air by means of at least one rotor (20) actuated by at least one engine (1 10) the method being implemented by an electronic optimization device (164),

the method comprising, during the flight of the drone (14), at least once, determining (172, 176, 184, 186) a maximum angle (0 _ma * _{, t} ) of inclination of the drone as a function of an information item (l _s ) representative of the saturation state of at least one engine of the drone.

2. - A method of optimizing the flight inclination of a drone (14) according to claim 1, wherein the implementation of the determination (172, 176, 184, 186) of the maximum angle {0 _maXit ) of flight inclination of the drone according to information (l _s ) representative of the saturation state of said at least one engine is conditioned by the value of the horizontal movement speed of the drone.

3. - A method of optimizing the flight inclination of a drone (14) according to claim 2, wherein the method comprises the comparison (170) of the horizontal velocity (V _H ) of movement of the drone (14) at a predetermined speed threshold (S _V H) -

4. - A method of optimizing the flight inclination of a drone (14) according to claim 3, wherein:

when the horizontal speed (V _H ) of movement of the drone is less than the predetermined speed threshold, the maximum flight angle (e _{max t} ) of the drone (14) is equal to a maximum value ( _max Val) predetermined inclination, and

when the horizontal speed (V _H ) of movement of the drone is greater than the predetermined speed threshold, the determination (172, 176, 184, 186) of the maximum flight angle (6max, t) of the drone in flight. function of information (l _s ) representative of the saturation state of said at least one engine (1 10) is implemented.

5. - A method of optimizing the flight angle of a drone according to claim 4, wherein the determination (172, 176, 184, 186) of the maximum angle (e _{max t} ) of flight inclination of the drone as a function of information (l _s ) representative of the saturation state of said at least one engine (1 10) comprises:

at the first engine saturation detected during the flight of the drone (14): measuring the angle of inclination (0 _C ) of the first motor saturation,

the storage of the tilt angle value of the first motor saturation,

the definition of the maximum angle of flight inclination of the drone as equal to the angle of inclination angle of the first engine saturation, then

at least one iteration of the following steps as long as the horizontal speed of movement of the drone is greater than the predetermined threshold:

- when the value of the information (l _s) representative represents the saturation of at least one motor, the maximum angle of UAV flight inclination is reduced by the angular velocity of saturation (V _sat) engine remains above or equal to a predetermined minimum inclination value,

- when the value of the information (l _s) representative represents no saturation engine, the maximum angle of UAV flight inclination is increased by the angular velocity of desaturation _(Dsa V t) less than or remaining engine equal to the predetermined maximum inclination value.

6. A method of optimizing the flight inclination of a drone according to any one of the preceding claims wherein the information (l _s ) representative of the saturation state of at least one engine of the drone is Boolean.

A computer program comprising software instructions which, when executed by a computer, implement a method as claimed in any one of the preceding claims.

An electronic flight tilt optimization device (1 64) of a rotary wing drone (14) adapted to move in the air by means of at least one rotor (20) actuated by at least one a motor (1 1 0), the electronic device (164) comprising at least one determination module (168) configured to determine a maximum angle (6max, t) of inclination of the drone as a function of information (l _s ) representative of the saturation state of at least one engine of the drone.

9. Apparatus (1 08) for controlling the engine (s) (1 10) of a rotary wing drone (14) capable of moving in the air by means of at least one rotor (20) actuated by at least one motor (1 1 0), wherein the electronic apparatus (1 08) comprises a control unit (1 62) configured to separately control each engine of the drone, by control passage in the mark of said engine and by automatic management of the engine saturation of said engine and the electronic flight tilt optimization device according to claim 8.

10. A rotary-wing drone (14) adapted to move in the air by means of at least one rotor (20) actuated by at least one engine (1 10), the drone (14) comprising at least one device electronic flight control optimization device (164) according to claim 8.