WO2018102989A1

WO2018102989A1 - An improved method of managing a flying drone and an improved drone system

Info

Publication number: WO2018102989A1
Application number: PCT/CN2016/108719
Authority: WO
Inventors: Liang Han; Nan Ye; Zhihong Guo
Original assignee: Orange
Priority date: 2016-12-06
Filing date: 2016-12-06
Publication date: 2018-06-14

Abstract

A method of managing a flying drone (DRO) using a remote controller (REM), the drone being adapted to define initial directions fixed in space which include initial forward, backward, left and right directions (FD, BD, LD, RD), the remote controller having an input module (INP) defining forward, backward, left and right inputs (F, B, L, R) and at least one operating mode in which the respective actuation of the forward, backward, left and right inputs (F, B, L, R) is configured to cause the drone to move along the corresponding initial forward, backward, left or right direction (FD, BD, LD, RD), the remote controller defining a remote direction (REMD) fixed relative to the remote controller and which varies as a function of the orientation of the remote controller around a vertical axis. The method comprises, while one operating mode of at least one operating mode is implemented: monitoring an orientation angle defined between a reference direction (REF) fixed relative to the initial directions and the remote direction around a vertical axis, and upon detection of the verification of at least one condition including a condition according to which the orientation angle has left a predetermined range, redefining the initial directions by rotating the initial directions by a predetermined angle around a vertical axis.

Description

An improved method of managing a flying drone and an improved drone system

The invention relates to a method of managing a flying drone.

Advanced drones capable of flying are usually adapted to be remotely controlled by a remote controller, which comprises actuators respectively associated to a movement of the drone according to a predefined corresponding direction (i.e. so that the global movement of the drone comprises a movement component parallel thereto) , such as forward, backward, left and right actuators.

Some drone systems include an operating mode in which the directions associated to the actuators of the remote controller are fixed in space. In such a mode, the drone system is configured so that a given actuator remains attached to a movement along a predefined direction in space regardless of the circumstances.

This may prove uneasy for the operator of the remote controller in some circumstances, in particular when the drone happens to fly around the operator of the remote controller.

The invention seeks to improve the situation.

To this end, the invention relates to a method of managing a flying drone using a remote controller, said drone being adapted to define initial directions fixed in space which include initial forward, backward, left and right directions, the remote controller having an input module defining forward, backward, left and right inputs and at least one operating mode in which the respective actuation of the forward, backward, left and right inputs is configured to cause the drone to move along the corresponding initial forward, backward, left or right direction, the remote controller defining a remote direction fixed relative to the remote controller and which varies as a function of the orientation of the remote controller around a vertical axis, the method comprising, while one operating mode of said at least one operating mode is implemented:

- monitoring an orientation angle defined between a reference direction fixed relative to the initial directions and the remote direction around a vertical axis,

- upon detection of the verification of at least one condition including a condition according to which the orientation angle has left a predetermined range, redefining the initial directions by rotating the initial directions by a predetermined angle around a vertical axis.

According to an aspect of the invention, the reference direction is chosen as one of the initial forward, backward, left and right directions.

According to an aspect of the invention, the reference direction is chosen as the initial forward direction.

According to an aspect of the invention, the predetermined range is chosen as [-90°； 90°] .

According to an aspect of the invention, the predetermined angle is chosen as a function of the remote direction at the instant the condition of the at least one condition becomes verified or all the conditions of the at least one condition become simultaneously verified

According to an aspect of the invention, the predetermined angle is chosen so that the initial forward direction as redefined is parallel to the remote direction at the instant the condition of the at least one condition becomes verified or all the conditions of the at least one condition become simultaneously verified.

According to an aspect of the invention, the predetermined angle is chosen equal to a value which does not depend on the remote direction at the instant the condition of the at least one condition becomes verified or all the conditions of the at least one condition become simultaneously verified

According to an aspect of the invention, the at least one condition comprises a condition configured to be verified if the orientation angle leaves the predetermined range for a duration greater or equal to a predetermined threshold.

According to an aspect of the invention, the at least one condition comprises a condition configured to be verified if the orientation angle is maintained within a predetermined angle range for a duration longer than a predetermined duration.

According to an aspect of the invention, upon redefinition of the initial directions, the drone is automatically controlled to face the initial forward direction as redefined.

According to an aspect of the invention, upon redefinition of the initial directions, the drone is brought to stationary flight.

The invention also relates to a computer program comprising instructions for the implementation of the method as defined above when executed by a processing module.

The invention also relates to a drone system comprising a drone adapted to fly and a remote controller for controlling the flight of the drone, the drone being adapted to define initial directions fixed in space which include initial forward, backward, left and right directions, the remote controller having an input module defining forward, backward, left and right inputs, the drone system having at least one operating mode in which the respective forward, backward, left and right inputs are configured upon respective actuation to cause the drone to move along the corresponding initial direction, the remote controller defining a remote direction fixed relative to the remote controller and which varies as a function of the orientation of the remote controller around a vertical axis, the drone system comprising:

- a management module configured to store a definition of the initial directions as a function of which the drone is displaced in response to the actuation of the respective forward, backward, left and right actuators in said at least one operating mode,

- a monitoring module operatively coupled to the management module, the monitoring module being configured to monitor an orientation angle defined between a reference direction fixed relative to the initial directions and the remote direction around a vertical axis,

the management module being further configured to redefine the initial directions by rotating the initial directions by a predetermined angle around a vertical axis in response to the detection by the monitoring module of the verification of at least one condition including a condition according to which the orientation angle has left a predetermined range.

According to an aspect of the invention, the monitoring module is located in the remote controller.

According to an aspect of the invention, the management module is located onboard the drone.

Further features of the invention will be better understood upon reading the detailed description below, given as a non-limiting example and made in reference to the appended Figures, in which:

- Figures 1a and 1b are illustrations of a drone system according to the invention；

- Figures 2a and 2b illustrate angles of interest of the drone system of Figure 1； and

- Figure 3 is a diagram of a method of operating a drone system according to the invention.

Figure 1a illustrates a drone system SYS according to the invention.

The drone system SYS includes a drone DRO and a remote controller REM. The remote controller is for instance operated by a user USER, who is for instance the owner of the drone system SYS. In the context of the invention, the drone DRO is capable of flying. In other words, it is a flying drone.

As illustrated in figure 1b, the drone may be a rotary wing drone. In other words, it includes one or more assemblies ASS each including a rotor (not shown) and one or more rotary wing W configured to be actuated at least by the corresponding rotor so as to sustain the drone and move the drone in space.

For instance, each wing includes one or more blades which can be controlled (for instance in a known manner) so as to change the orientation of the drone (typically in terms of yaw, pitch and roll) , its altitude, its speed, etc, so as to have the drone move in space.

For instance, the drone DRO comprises 4 such assemblies ASS. These assemblies are for instance located near extremities of the drone, such as extremity of arms of a main body of the drone which extend outwardly. The main body may have any shape, the shape shown in the Figures merely being exemplary.

As illustrated in fig. 1a, the drone DRO further includes a flight control module FCM configured to manage the flight of the drone DRO, as well as a communication module COM configured for communications with the remote controller REM.

The communication module COM is for instance a radiofrequency (RF) module configured to receive communication signals generated by the remote controller REM and conveyed to the drone using electromagnetic waves. This communication module COM may include an antenna capable of transducing the electromagnetic waves conveying the communication signals, as well as a processing module (not shown) adapted to process the transduced signal to actually retrieve the content of the communication signals.

Any wireless communication technology may be used in the stead of radiofrequencies, such as WiFi, Bluetooth, or any other type of radio transmission. In some embodiments, a cable communication may be used, although wireless technologies are preferred.

Optionally, the communication module COM is also adapted to send communication signals to the remote controller REM. In other words, advantageously, the communication module COM is a bidirectional module for exchanges of data both ways between the remote controller REM and the drone DRO.

The flight control module FCM is configured to control the various mobile surfaces of the drone (which may include other mobile elements besides the wings of the assemblies) , in particular so as to move the drone in space.

This control is made as a function of inputs performed by the user using the remote controller REM, which are communicated to the drone and are detailed below.

The flight control module FCM is thus configured to process the inputs received from the user and generate, based on the latter, control signals destined to actuators of the mobile surfaces of the drone, whereby these actuators move these surfaces accordingly to obtain the desired movement of the drone in space. In particular, it is configured to generate such signals for the rotors which actuate the rotary wings, these rotors forming the sole actuators of the drone in some embodiments.

The flight control module FCM may take various forms. Advantageously, it includes an integrated circuit which includes a processing module and a memory module configured to store programs whose execution by the processing module causes the flight control module to operate. It may further include one or more controller, which is for instance designed to generate respective control signals destined to the various actuators in the appropriate format on the basis of instructions received from the processing module (these controllers may also form part of the processing module itself) .

Still in reference to Figures 1a and 1b, the remote controller REM is configured to allow the user USER to control the flight of the drone. For that purpose, the remote controller REM includes a communication interface INT (illustrated on Figure 1a) , and an input module INP (illustrated on Figure 1b) .

The communication interface INT is configured to allow communication signals at least to be transmitted from the remote controller REM to the drone DRO.

The interface INT for instance includes an antenna ANT capable of at least generating electromagnetic waves which are representative of the content of the communication signals to be conveyed to the drone, as well as a control module CONT configured to control the operations of the antenna ANT for these communication signals. The antenna ANT includes a protruding portion relative to a face of the remote controller, such as a transverse face of the latter which for instance forms an upper front face of the drone.

Optionally, the interface INT is configured to allow bidirectional communications between the drone DRO and the remote controller REM, and thus may receive communication signals from the drone DRO.

The input module INP is configured to allow the user to input commands for the control of the flight of the drone DRO. It is operatively coupled to the communication interface and is configured to process an input performed therewith to generate a signal destined to be transformed by the interface INT into a communication signal destined to the drone DRO.

In the context of the invention, advantageously, the input module INP defines forward F, backward B, left L and right R inputs which are adapted to be actuated. The result of the actuation of a given input may vary depending of the operating mode of the drone DRO and of the drone system SYS. This is discussed in more details below.

For instance, these inputs may be defined by one or more components of the input module INP, such as on or more buttons.

Advantageously, they are defined by a single component of the input module INP, such as a lever LEV. This lever is movable for instance along at least four directions each corresponding to one of the inputs. In other words, a movement of the lever according to one of these directions corresponds to the actuation of the corresponding input.

The lever LEV may be adapted so as to define a simultaneous actuation of more than one input at a given time, for instance both a left and forward input. For instance, to that end, it may present itself in the form of a ball-jointed lever.

The input module INP may include further components in addition to the lever LEV, such as buttons, one or more additional lever, etc. All or part of these elements (and optionally the lever LEV itself) may be combined with a display so as to form a tactile display. These elements are associated to a control of the other components of the behavior of the drone, such as its altitude and its speed.

In the context of the invention, the system SYS further comprises a management module MAN and a monitoring module MON. They are operatively coupled to one another.

These modules MAN and MON may be located in the drone DRO or in the remote controller REM, or may for one be located in the remote controller REM and for the other in the drone DRO. In case of a distributed configuration, the interface INT and the communication module MOD are configured for bidirectional communications, whereby the modules MAN, MON are in communication with one another through these components.

Advantageously, the monitoring module MON is located in the remote controller REM.

The management module MAN is for instance located in the drone where it may advantageously form part of the flight control module FCM.

The management module MAN is configured to store a definition of initial directions which are used as reference directions to move the drone using the forward, backward, left, right inputs of the input module INP in at least one operating mode of the drone DRO.

These initial directions advantageously include initial forward FD, backward BD, left LD and right RD directions. These initial directions are fixed in space (but may be redefined at certain points in time, as detailed below) . The initial directions are for instance contained in a horizontal plane.

In the corresponding operating modes, the drone system is configured to cause a movement of the drone along a given initial direction upon actuation of the corresponding input of the remote controller REM.

In other words, when the user actuates the left input, the drone displaces itself along the corresponding initial left direction (possibly together with a movement along another direction, as indicated above) . The same applies to the other inputs.

In effect, this behavior results of the configuration of the flight control module FCM, which processes the inputs received and generates command signals destined to the actuators of the drone according to the definition of the initial directions. As such, the definition of the initial direction is advantageously stored in the flight control module FCM, in addition to the management module MAN when the latter does not form part of the flight control module.

For instance, the forward and backward directions correspond to a same axis, each corresponding to opposite directions of this axis. Similarly, the left and right initial directions may correspond to opposite directions of a same axis.

These initial directions may be defined by the drone in response to its being powered on. For instance, the initial forward direction FD may be defined by the axis along which the drone stretches, and chosen to correspond to the direction towards which the nose of the drone points at a predetermined instant relative to the instant the drone is powered on (these instants may correspond) .

The other initial directions may be defined relatively to the forward direction, the left and right directions being rotated by 90° and the backward direction by 180° relative to the forward direction around a chosen vertical axis. This axis may pass through a point of reference of the drone at the corresponding instant, such as a center C of the drone.

Alternatively, they may be the object of a dedicated definition and may be defined by the direction towards which a given portion of the drone points, such as a starboard side for the right direction, a port side for the left direction, a tail portion for the backward direction.

Advantageously, regardless of the definition process of these initial directions, the angle between two adjacent initial directions (for instance between the forward direction and the left direction) is 90°. This angle is an absolute (i.e. non oriented) angle, and may correspond to two different oriented angles if an oriented angle is considered.

The management module MAN is further configured to redefine the initial directions in response to the verification of one or more conditions.

The verification of at least part of these conditions is tracked by the monitoring module MON.

In reference to Figure 2a, at least one condition which is tracked by the monitoring module MON is defined to be verified when an orientation angle θ defined between a reference direction REF fixed relative to the initial directions and a remote direction REMD defined by the remote controlled REM around a vertical axis leaves a predetermined range.

The reference direction REF is for instance a horizontal direction. In effect, it characterizes the definition of the initial directions.

Advantageously, the reference direction REF is chosen as one of the initial directions themselves, such as the initial forward direction FD. The definition of the reference direction is for instance stored by the management module MAN along with the definition of the initial directions.

The remote direction REMD is defined by the remote controller. It is fixed relative to the remote controller REM. In effect, it is representative of the orientation of the remote controller REM around a vertical axis. This axis for instance passes through the remote controller REM itself.

For instance, this remote direction REMD corresponds to that of the antenna, which optionally protrudes from the remote controller REM.

In effect, this remote direction REMD varies over time, in particular along with the rotations around a vertical axis of the remote controller REM imparted to it by the user USER, which may typically be the case when the user USER rotates himself.

To the end of monitoring the orientation angle θ, the monitoring module MON includes one or more sensors S configured to sense the orientation of the remote controller and/or sense changes of the orientation of the remote controller, i.e. changes of the remote direction REMD.

For instance, the sensors include a magnetometer, or at least one accelerometer and one gyroscope. In effect, the output of the sensor (s) is processed as a function of the definition of the reference direction to provide the orientation angle. To that end, the definition of the reference direction and/or of the initial directions may be stored locally by the monitoring module MON, in particular if the monitoring module is located in the remote controller REM and the management module MAN is not. This definition is for instance provided by the management module MAN itself on the basis of the stored definition.

It should be noted that the sensors S may be independent, i.e. located outside, from the monitoring module MON, and from the remote controller REM and the drone DRO altogether. They may form part of another device, such as a smartphone, which is operatively coupled to the remote controller REM, for instance through a plug-in or wireless interface.

Two different values of the orientation angle are illustrated in Figures 1b and 2a, each corresponding to one of two positions POS1, POS2 of the remote controller REM with corresponding values of the orientation angle noted θ₁ and θ₂.

In the first position (POS1) , the remote direction REMD is aligned with the reference direction REF (chosen as the forward direction as an example) .

In the second position (POS2) , the remote direction REMD forms an obtuse angle with the reference direction REF (approximately 120° in absolute value) .

Advantageously, the predetermined range is chosen as [-90°； 90°] . This range is considered for an oriented angle. In case an angle in absolute value is considered, this range is equivalent to [0°, 90°] .

In effect, the orientation angle leaves this range when the user points the remote controller REM in a direction which is away from the drone DRO.

Other predetermined ranges [-X, X] may be considered. For instance, X may take any value between 10° and 180°. However, X is advantageously chosen in the [20°； 90°] range.

Advantageously, upon power up of the drone DRO, it may be considered that the orientation angle is within the predetermined range regardless of whether it is or not for a predetermined duration. This prevents the condition (s) from being verified during an initial phase of the operations of the drone.

Another condition which may be employed is configured to be verified if the orientation angle leaves the predetermined range for a duration greater than a predetermined threshold. In other words, this condition is itself verified if the previous condition is verified long enough.

This prevents the various conditions being simultaneously verified if the orientation is made to leave the predetermined range unintentionally by the user, in which case the user will tend to move the remote controller in the general direction of the drone quickly, thereby reducing the value of the orientation angle.

Another condition which may be used (for instance in conjunction with at least the first condition above) is defined to be verified if the orientation angle is maintained within a predetermined angle range for a duration longer than a predetermined duration. In other words, this condition is verified if the orientation angle is maintained sufficiently close to the center of the predetermined angle range long enough.

This predetermined range has a chosen width, for instance between 20° and 60°. It is centered on a direction which is advantageously chosen to correspond to the direction which is detected in response to a predetermine criterion, such as the variation rate of the orientation angle. For instance, it is chosen to correspond to the remote direction REMD at the instant the variation rate of the orientation angle falls below a threshold, which represents the fact that the user has stopped moving the remote direction around and points it in a given direction.

Advantageously, the condition regarding the orientation angle leaving the predetermined range is systematically used.

As indicated above, the management module MAN is configured, upon the condition being verified if solely one is used or upon the conditions being simultaneously verified if several are used, to redefine the initial directions.

Advantageously, in reference to Figure 2b, this redefinition is carried out through a simultaneous rotation of the initial directions by a predetermined angle α around a vertical axis. A given initial direction as redefined and this initial direction as previously defined define an angle α between them around a vertical axis. On Figure 2b, the initial forward direction as redefined FD’a nd the initial forward direction FD as previously defined define an angle α between them around a vertical axis (the same applying to the other initial directions) .

For instance, this axes passes through the point of reference of the drone (point C in Figure 1b) , or through the intersection of the respective axis of the initial directions.

In effect, this redefinition includes, and preferably consists in, reorienting (i.e. rotating) the planar referential defined by initial definition so as to keep the relative positions of the initial directions and have them aligned with new spatial directions.

Advantageously, the angle α is chosen as a function of the remote direction REMD at the instant the condition of the at least one condition becomes verified or all the conditions of the at least one condition become simultaneously verified.

For instance, this angle α is chosen so that the initial forward direction FD’a s redefined is parallel to the remote direction REMD at the instant the condition of the at least one condition becomes verified or all the conditions of the at least one condition become simultaneously verified. In other words, the angle α is taken equal to the orientation angle θ at the instant the condition or all the conditions are simultaneously verified (the direction of rotation being respected, i.e. clockwise if the orientation is measured clockwise, or counter-clockwise if it is measured counter-clockwise) . Preferably, this is so when a plurality of conditions is used. This allows the user to fully customize the redefinition of the initial directions.

Alternatively, the angle α does not depend on the remote direction REMD at the instant the conditions are simultaneously verified. For instance, it is taken equal to an arbitrary predefined value. This value is for instance taken equal to 180°. Other values may be considered.

In particular, the value of α may be chosen as a function of the width of the predetermined range. It may be chosen as half this width when the orientation angle is an oriented angle, or equal to this width for a non-oriented angle. This is particularly interesting in case the condition regarding the orientation leaving the predetermined range is solely used.

Advantageously (i.e. in an optional but interesting embodiment) , the drone DRO is brought to a stationary flight upon redefinition of the initial directions.

Advantageously, the drone DRO is controlled so as to have its nose face the initial forward direction as redefined upon redefinition of the initial directions.

A method of controlling the drone DRO using the remote controller REM will now be described in reference to Figure 3.

In a step S1, the drone DRO is powered up.

Once powered up, the initial directions are defined by the drone DRO during a step S2, as described above. Once defined, these initial directions are stored by the management module MAN. The reference direction REF is defined as well on the basis of this definition, its own definition being stored as well.

The user USER then controls the movements of the drone DRO using the remote controller REM, in particular the input module INP. The inputs made on the input module INP are processed to form one or more communications sent the drone DRO using the interface INT and the communication module COM, and are provided to the flight control module FCM which generates control signals destined to the actuators of the drone to move the drone DRO according to the inputs.

At a step S3, an operating mode of the drone system in which the initial directions are active is triggered, for instance in response to an input made by the user USER on the remote controller REM. In effect, once triggered, as described above, the inputs F, B, L, R each cause a displacement of the drone along the corresponding initial direction FD, BD, LD, RD, i.e. so that the overall movement of the drone includes a component parallel to the corresponding initial direction.

In addition, the monitoring module MON monitors the value of the orientation angle θ defined by the reference direction REF and the remote direction REMD.

The condition (s) regarding the orientation angle are checked (for instance at regular intervals) , in particular the condition regarding the orientation angle leaving the predetermined range.

If a plurality of conditions is used, the other conditions may not be checked if this condition is not verified.

At a step S4 which is triggered by the verification of the unique condition used or of all the conditions used simultaneously, the management module MAN proceeds to redefine the initial directions.

In effect, the management module MAN is informed that the conditions are verified by the monitoring module MON, and proceeds to modify the definition of the initial direction through a reorientation of the initial directions on the basis of the chosen modality for the angle α. The reference direction REF is redefined as well accordingly.

The new definition of the initial directions (and of the reference direction) is for instance communicated to the monitoring module MON and to the flight control module FCM.

When the user USER actuates an input among the F, B, L, R inputs, it still causes the drone to move along the corresponding initial direction, but this initial direction has itself changed.

While the operating mode is maintained implemented, the checking of the condition (s) is performed in a repeated manner, the verification of the condition (s) giving ground each time to a redefinition of the initial directions.

The invention presents several advantages.

In fact, it allows for real-time adjustments of a principle used for controlling flying drones. In addition, the adjustments themselves are greatly customizable.

It should be noted that the principle of the invention may be implemented by several different operating modes of the drone system, which may differ in that the modalities used for redefining the initial directions are different. For instance, in one mode, the angle α is taken as an arbitrary value, whereas in another mode, this value is determined as a function of the remote direction REMD at the instant the condition (s) tracked by the monitoring mode becomes verified. Moreover, in one mode, a single condition may be used to trigger the redefinition of the initial directions, whereas in another mode, a plurality of them is used.

The invention also relates to a computer program comprising instructions whose execution by at least one processor translates into the method above being implemented. This program may be stored in a memory component of the management module. It may also be divided into sub-programs respectively stored in memory components of the managing module and of the monitoring module.

It should be noted that the term “initial” in the expression “initial direction” is merely present for the sake of allowing a clear distinction between the initial directions and the reference direction used to define the orientation angle. In effect, the initial directions are merely reference directions used to move the drone in space in the corresponding operating mode and may be named as such. In addition, the reference direction may be seen as a mere arbitrary direction and may be thus named as such.

Claims

A method of managing a flying drone (DRO) using a remote controller (REM) , said drone being adapted to define initial directions fixed in space which include initial forward, backward, left and right directions (FD, BD, LD, RD) , the remote controller having an input module (INP) defining forward, backward, left and right inputs (F, B, L, R) and at least one operating mode in which the respective actuation of the forward, backward, left and right inputs (F, B, L, R) is configured to cause the drone to move along the corresponding initial forward, backward, left or right direction (FD, BD, LD, RD) , the remote controller (REM) defining a remote direction (REMD) fixed relative to the remote controller (REM) and which varies as a function of the orientation of the remote controller (REM) around a vertical axis, the method comprising, while one operating mode of said at least one operating mode is implemented:

-monitoring an orientation angle (θ) defined between a reference direction (REF) fixed relative to the initial directions and the remote direction (REMD) around a vertical axis,

-upon detection of the verification of at least one condition including a condition according to which the orientation angle (θ) has left a predetermined range, redefining the initial directions by rotating the initial directions by a predetermined angle (α) around a vertical axis.
The method according to claim 1, wherein the reference direction (REF) is chosen as one of the initial forward, backward, left and right directions (FD, BD, LD, RD) .
The method according to claim 2, wherein the reference direction is chosen as the initial forward direction (FD) .
The method according to any one of the preceding claims, wherein the predetermined range is chosen as [-90°； 90°] .
The method according to any one of the preceding claims, wherein the predetermined angle (α) is chosen as a function of the remote direction (REMD) at the instant the condition of the at least one condition becomes verified or all the conditions of the at least one condition become simultaneously verified.
The method according to claim 5, wherein the predetermined angle (α) is chosen so that the initial forward direction (FD’ ) as redefined is parallel to the remote direction (REMD) at the instant the condition of the at least one condition becomes verified or all the conditions of the at least one condition become simultaneously verified.
The method according to any one of claims 1 to 4, wherein the predetermined angle (α) is chosen equal to a value which does not depend on the remote direction (REMD) at the instant the condition of the at least one condition becomes verified or all the conditions of the at least one condition become simultaneously verified.
The method according to any one of the preceding claims, wherein the at least one condition comprises a condition configured to be verified if the orientation angle (θ) leaves the predetermined range for a duration greater or equal to a predetermined threshold.
The method according to any one of the preceding claims, wherein the at least one condition comprises a condition configured to be verified if the orientation angle (θ) is maintained within a predetermined angle range for a duration longer than a predetermined duration.
The method according to any of the preceding claims, wherein upon redefinition of the initial directions, the drone (DRO) is automatically controlled to face the initial forward direction (FD) as redefined.
The method according to any of the preceding claims, wherein upon redefinition of the initial directions, the drone (DRO) is brought to stationary flight.
A computer program comprising instructions for the implementation of the method according to any one of the preceding claims when executed by a processing module.
A drone system (SYS) comprising a drone (DRO) adapted to fly and a remote controller (REM) for controlling the flight of the drone, the drone being adapted to define initial directions fixed in space which include initial forward, backward, left and right directions (FD, BD, LD, RD) , the remote controller (REM) having an input module (INP) defining forward, backward, left and right inputs (F, B, L, R) , the drone system (SYS) having at least one operating mode in which the respective forward, backward, left and right inputs (F, B, L, R) are configured upon respective actuation to cause the drone to move along the corresponding initial forward, backward, left or right direction (FD, BD, LD, RD) , the remote controller (REM) defining a remote direction (REMD) fixed relative to the remote controller (REM) and which varies as a function of the orientation of the remote controller (REM) around a vertical axis, the drone system comprising :

-a management module (MAN) configured to store a definition of the initial directions as a function of which the drone (DRO) is displaced in response to the actuation of the respective forward, backward, left and right actuators in said at least one operating mode,

-a monitoring module (MON) operatively coupled to the management module (MAN) , the monitoring module (MON) being configured to monitor an orientation angle (θ) defined between a reference direction (REF) fixed relative to the initial directions and the remote direction (REMD) around a vertical axis,

the management module (MAN) being further configured to redefine the initial directions by rotating the initial directions by a predetermined angle around a vertical axis in response to the detection by the monitoring module of the verification of at least one condition including a condition according to which the orientation angle (θ) has left a predetermined range.
A drone system according to claim 13, wherein the monitoring module (MON) is located in the remote controller (REM) .
A drone system according to claim 13 or 14, wherein the management module (MAN) is located onboard the drone (DRO) .