Method for controlling an aircraft taxiing system

Abstract

The present invention relates to a method for controlling an aircraft taxiing system, comprising the following steps: generating a traction command (Com) for controlling an electric motor of a wheel drive actuator; detecting whether an external braking command is generated, the external braking command being intended to control wheel braking by means of a brake; if the external braking command is generated, generating a predetermined minimum command (Cmp) for controlling the electric motor so that the drive actuator applies a predetermined minimum motor torque on the wheel during braking, the minimum motor torque being strictly positive; detecting whether the speed of the aircraft becomes zero, and if so, disabling the predetermined minimum command (Cmp) so that the drive actuator applies zero torque on the wheel.

Description

[0001] The present invention relates to the field of aircraft taxiing systems. Background Art

[0002] It is envisaged to equip certain modern aircraft with a taxiing system which enables the aircraft to move autonomously on the ground, ie without using the aircraft's main motors.

[0003] Taxi systems typically include a plurality of drive actuators, each for rotating one of the aircraft's wheels.

[0004] Taxi systems are typically electrical systems in which each drive actuator is an electromechanical actuator including an electric motor.

[0005] When the aircraft pilot decides to use the taxiing system to move the aircraft on the ground, it generates a traction setpoint to control the motor of each drive actuator so that said drive actuator applies a traction motor torque on the associated wheel, which makes it possible to move the aircraft. The traction motor torque is provided at the start of the taxiing system and throughout the mission.

[0006] However, when the taxiing system is used to move the aircraft on the ground and the pilot decides to brake the aircraft, the kinetic energy of the aircraft is such that the drive actuator and its power system cannot be used to ensure the braking function.

[0007] In fact, the instantaneous power is too large to ensure a deceleration of the aircraft compatible with the required deceleration or braking distance. Such an instantaneous power would result in an unacceptable current density.

[0008] Furthermore, the kinetic energy of the vehicle is very high and will require either the use of huge electrical energy storage capacities or the implementation of a means of "burning" this huge amount of electrical energy.

[0009] Thus, when the taxi system is used to move the aircraft forward on the ground, braking of the aircraft is not achieved by driving actuators but by friction brakes which usually equip the braking wheels of the aircraft.

[0010] Purpose of the Invention

[0011] The purpose of the present invention is to improve the mechanical strength and reliability of an aircraft taxiing system. Summary of the invention

[0012] To achieve this object, a method for controlling an aircraft taxiing system is proposed, the taxiing system comprising at least one drive actuator arranged to rotate a wheel of the aircraft, the wheel also being equipped with a brake separate from the drive actuator, the control method comprising the following steps:

[0013] generating a traction command for controlling a motor of a drive actuator so that the drive actuator applies a traction motor torque to the wheel to move the aircraft over the ground;

[0014] detecting whether an external braking command is generated, the external braking command being intended to instruct braking of the wheel via a brake;

[0015] If an external braking command is generated, generating a predetermined minimum command to control the electric machine so that the drive actuator applies a predetermined minimum electric machine torque on the wheel during braking, the torque being strictly positive;

[0016] It is detected whether the speed of the aircraft becomes zero, and if so, the predetermined minimum command is disabled so that the drive actuator applies zero torque on the wheel.

[0017] Thus, when an external braking command is detected and when the wheel is braked by the brake (and not the drive actuator itself), the motor of the drive actuator is not deactivated but rather controlled such that the drive actuator exerts a predetermined minimum torque on the wheel.

[0018] Deactivation of the motor will result in the mechanical elements of the drive actuator being idle during braking, which will generate noise and vibrations during braking, which will tend to mechanically degrade the motor and drive actuator.

[0019] On the contrary, when using the control method according to the invention, the predetermined motor torque makes it possible to ensure contact between the teeth integral to the rotation of the motor rotor and those integral to the wheel. Maintaining this contact during braking makes it possible to significantly reduce the above-mentioned noise and vibrations and thus improve the mechanical strength and reliability of the taxiing system.

[0020] In particular, the predetermined minimum motor torque is defined to ensure that during braking, the predetermined minimum command cannot generate a negative quadratic axis current.

[0021] In particular, the predetermined minimum command is defined such that the minimum quadrature axis current Iqmin is as follows:

[0022] Iqmin>Idmax.sin(θm),

[0023] Where Idmax is the maximum defluxing current that can be applied, and θm is the maximum angular measurement error of an angular position sensor of the motor rotor used to control the motor.

[0024] In particular, the predetermined minimum motor torque is between 400 N.m and 600 N.m.

[0025] In particular, the external braking command is generated by a pilot of the aircraft using a brake pedal, and the detection of the generation of the external braking command comprises the steps of acquiring an estimate of the pressure on the brake pedal and comparing the estimate of the pressure with at least one predetermined threshold.

[0026] The invention also relates to a control system arranged to implement such a control method, the control system comprising:

[0027] a control / command module arranged to generate a traction command; a brake detection module arranged to detect whether the external brake command is generated;

[0028] an application module arranged to generate said predetermined minimum command;

[0029] a zero speed detection module, arranged to detect whether the speed of the aircraft becomes zero;

[0030] A disabling module is arranged to disable the predetermined minimum command when the speed of the aircraft becomes zero.

[0031] In particular, the brake detection module comprises a hysteresis comparator comprising a first input terminal to which an estimate of the pressure on the brake pedal is applied, a second input terminal to which a high predetermined threshold is applied and a third input terminal to which a low predetermined threshold is applied, the hysteresis comparator being arranged to perform a comparison of the estimate of the pressure with the high predetermined threshold and the low predetermined threshold.

[0032] In particular, the application module includes a first bidirectional switch having a first input terminal to which a predetermined minimum command is applied, a second input terminal to which a traction command is applied, an output terminal and a command input terminal to which a brake detection signal is applied, wherein the brake detection signal represents a result of a brake detection.

[0033] In particular, the application module includes a second bidirectional switch having a first input terminal to which a zero torque command is applied, a second input terminal to which the output of the first bidirectional switch is applied, and a command input terminal to which a zero speed detection signal is applied, the zero speed detection signal indicating a result of zero speed detection of the aircraft.

[0034] The present invention may be better understood in light of the following description of certain non-limiting embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] With reference to the accompanying drawings, in which:

[0036] Figure 1 means a system for controlling the taxiing system of an aircraft;

[0037] Figure 2shows a graph showing the operating point of the motor driving the actuator in Park's reference frame when the torque generated is a traction torque;

[0038] Figure 3 Shown with Figure 2 A diagram similar to the diagram of , including the real quadrature axis and the direct axis, as well as the theoretical quadrature axis and the direct axis;

[0039] Figure 4 shows the relationship between the Figure 2 A similar chart to the one shown in the figure below;

[0040] Figure 5 Shown with Figure 4 A similar diagram to the diagram of , including real quadrature and direct axes, and theoretical quadrature and direct axes;

[0041] Figure 6 A graph including curves of motor torque / speed characteristics is shown. DETAILED DESCRIPTION

[0042] In this case, the invention is implemented in an aircraft comprising a plurality of landing gears, at the bottom of which wheels are mounted. The aircraft also comprises a braking system which enables the aircraft to be braked on the ground, and a taxiing system which enables the aircraft to be moved on the ground without using its main engines. In this case, the braking system is a hydraulically actuated system, but it may also be a completely different system, for example with electric or electrohydraulic actuation. In this case, the taxiing system is an electrically actuated system.

[0043] Some wheels of an aircraft are equipped with both brakes belonging to the braking system and drive actuators belonging to the taxiing system.

[0044] The brake of each of these wheels comprises a crown carrying a plurality of brake actuators. A torsion tube is fixed to the crown. The torsion tube extends into the wheel rim. The friction brake also comprises a disc stack consisting of a rotor rotating integrally with the wheel rim and a stator rotating integrally with the torsion tube. The brake actuators are arranged to selectively exert pressure on the discs during the intake of pressurized fluid, thereby generating a braking torque.

[0045] The braking system also includes a left-hand brake pedal enabling the pilot to command the brakes of the wheels located on the left-hand side of the aircraft and a right-hand brake pedal enabling the pilot to command the brakes of the wheels located on the right-hand side of the aircraft.

[0046] Therefore, the taxiing system comprises drive actuators. Each drive actuator of a wheel is used to rotate the wheel. Each drive actuator is an electromechanical actuator, which comprises an electric motor including a stator and a rotor.

[0047] The drive actuator comprises a gear train. The gear train comprises a first gear that rotates integrally with the rotor of the motor and comprises first teeth, and a second gear that rotates integrally with the wheel and comprises second teeth. The gear train may further comprise one or more other gears, or a clutch device, or another mechanical connection element between the first gear and the second gear.

[0048] When the drive actuator is in a so-called "engaged" position, the first gear meshes with the second gear, thereby enabling the drive actuator to apply traction motor torque to rotate the wheels and thereby move the aircraft over the ground.

[0049] In addition to the drive actuator, the taxiing system also comprises a control system for said taxiing system, which operates as follows.

[0050] When the pilot generates a traction setpoint to move the aircraft on the ground by means of the taxi system, the control system generates a traction command to control the motor of the drive actuator of each wheel so that the drive actuator applies a traction motor torque to the wheel for moving the aircraft on the ground.

[0051] Therefore, the control system detects whether an external braking command is generated which aims at commanding wheel braking.

[0052] In this case, the external brake command is generated by the driver through an action on the brake pedal. Note that the external brake command can also be generated differently, for example by an automatic control system.

[0053] The external braking command is intended to brake the aircraft on the ground by acting on the brakes of the braking system (not on the drive actuators).The brakes of the wheels are separate from the drive actuators of said wheels, ie they are two different devices, not integrated with each other.

[0054] If an external braking command is generated, the control system generates a predetermined minimum command to control the electric machine so that the drive actuator applies a predetermined minimum electric machine torque to the wheel. The predetermined minimum electric machine torque is strictly positive.

[0055] Thus, when the pilot commands the braking of the aircraft, the braking is therefore performed for each wheel not by means of a drive actuator, which in any case generates a motor torque in the same direction that is non-zero but equal to a predetermined minimum motor torque, but by means of the brakes of the wheels. The predetermined minimum motor torque makes it possible to ensure contact between the first tooth rotating integrally with the rotor of the motor and the second tooth rotating integrally with the wheel during braking.

[0056] In this way, the control system detects whether the speed of the aircraft has become zero and, if so, the control system inhibits the predetermined minimum command, thereby driving the actuator to apply zero torque to the wheels.

[0057] For this purpose, refer to Figure 1 , the control system 1 comprises firstly a command interface 2 integrated in the cockpit, which allows the pilot to control the taxiing system. The command interface 2 comprises a rotary button 3 and a percentage scale (from 0 to 100%) to generate a traction setpoint Cons.

[0058] The control system 1 further comprises a control / command module 5 , a zero speed detection module 6 , a brake detection module 7 , an application module 8 and a prohibition module 9 .

[0059] In this case, it should be noted that these modules can be implemented by hardware and / or software means and integrated in one or more devices (computers, controllers, data concentrators, etc.).

[0060] The control / command module 5 acquires the traction setpoint Cons and the speed estimate of the vehicle Va, executes the control / command law, and generates a traction command Com.

[0061] Zero speed detection module 6 collects the speed estimate of aircraft Va and detects the speed of aircraft V a The speed estimation is zero and a zero speed detection signal Sdv indicating the result of the detection is generated.

[0062] The brake detection module 7 includes a first hysteresis comparator 10 and a second hysteresis comparator 11 .

[0063] The first hysteresis comparator 10 comprises a first input terminal, a second input terminal and a third input terminal, to which the estimate Es1 (expressed as a percentage) of the driver's pressure on the left-hand brake pedal is applied, to which a high predetermined threshold value Sph (expressed as a percentage) is applied, and to which a low predetermined threshold value Spb (expressed as a percentage) is applied.

[0064] Similarly, the second hysteresis comparator 11 includes a first input terminal, a second input terminal and a third input terminal, and the estimate Es2 (expressed as a percentage) of the driver's pressure on the right-hand brake pedal is applied to the first input terminal, the high predetermined threshold Sph is applied to the second input terminal, and the low predetermined threshold Spb is applied to the third input terminal.

[0065] The brake detection module 7 further comprises a first validator block 14 and a second validator block 15 .

[0066] The first confirmer block 14 includes a first input terminal connected to the output terminal of the first hysteresis comparator 10, a second input terminal and a third input terminal to which the confirmation time Tc is applied, and a fourth input terminal to which the sampling frequency fe is applied.

[0067] Likewise, the second validator block 15 includes a first input terminal connected to the output terminal of the second hysteresis comparator 11, a second input terminal and a third input terminal to which the validation time Tc is applied, and a fourth input terminal to which the sampling frequency fe is applied.

[0068] The application module 8 comprises a first bidirectional switch 16 having a first input to which a predetermined minimum command Cmp is applied, a second input connected to the output of the control / command module 5 , and a command input connected to the output of the first validator block 14 .

[0069] The application module 8 comprises a first bidirectional switch 17 having a first input to which a predetermined minimum command Cmp is applied, a second input connected to the output of the control / command module 5 , and a command input connected to the output of the first validator block 15 .

[0070] The disabling module 9 comprises a second bidirectional switch 18 having a first input terminal to which a zero torque command Ccn (equal to 0 N.m) is applied, a second input terminal connected to the output terminal of the first bidirectional switch 16 of the application module 8, and a command input terminal connected to the output terminal of the zero speed detection module 6.

[0071] The disabling module 9 also includes a second bidirectional switch 19 having a first input terminal to which a zero torque command Ccn (equal to 0 N.m) is applied, a second input terminal connected to the output terminal of the first bidirectional switch 17 of the application module 8, and a command input terminal connected to the output terminal of the zero speed detection module 6.

[0072] The operation of the control system 1 will now be described in more detail.

[0073] When the pilot generates a traction setpoint Cons to move the aircraft on the ground by using the command interface 2 , the control / command module 5 generates a traction command Com making it possible to move the aircraft on the ground.

[0074] As mentioned above, it is the braking system that is used to brake the aircraft.

[0075] When the speed of the aircraft is non-zero and braking is commanded, the control system 1 makes it possible to apply a predetermined minimum motor torque to each wheel.

[0076] The brake detection module 7 makes it possible to detect whether a brake command is generated.

[0077] To this end, the first hysteresis comparator 10 compares the estimate Es1 of the driver's pressure on the left-hand brake pedal with an upper predetermined threshold value Sph and a lower predetermined threshold value Spb. The hysteresis makes it possible to avoid unintentional state changes of the braking phase state.

[0078] Likewise, the second hysteresis comparator 11 compares the estimate Es2 of the driver's pressure on the right-hand brake pedal with an upper predetermined threshold value Sph and a lower predetermined threshold value Spb.

[0079] When the state (braking detected or not detected) is maintained for a duration greater than or equal to the confirmation time Tc, the first validator block 14 enables confirmation of the detection of the left-hand brake. The first validator block 14 generates at its output a brake detection signal Sdf1 representing the detection of the brake on the left-hand side of the aircraft.

[0080] Similarly, the second validator block 15 makes it possible to confirm the detection of braking on the right-hand side when the state (braking detected or braking not detected) is maintained for a duration greater than or equal to the confirmation time Tc. The second validator block 15 generates at its output a braking detection signal Sdf2 representing the detection result of braking on the right-hand side of the aircraft.

[0081] If the first confirmer block 14 generates an active brake detection signal Sdf1, meaning that an external brake command has been generated by the left-hand side brake pedal, the first input terminal of the first bidirectional switch 16 of the application module 8 is connected to the output terminal of the first bidirectional switch 16, and therefore the predetermined minimum command Cmp is applied to the output terminal of the bidirectional switch 16.

[0082] However, if the first validator block 14 generates an inactive brake detection signal Sdf1 , the second input of the first bidirectional switch 16 of the application module 8 is connected to the output of the first bidirectional switch 16 , and thus the traction command Com is applied to the output of the first bidirectional switch 16 .

[0083] Similarly, if the second confirmer block 15 generates an active brake detection signal Sdf2, which means that an external braking command has been generated by the right-hand brake pedal, the first input terminal of the first bidirectional switch 17 of the application module 8 is connected to the output terminal of the first bidirectional switch 17, and therefore, the predetermined minimum command Cmp is applied to the output terminal of the first bidirectional switch 17.

[0084] However, if the second validator block 15 generates an inactive brake detection signal Sdf2 , the second input of the first bidirectional switch 17 of the application module 8 is connected to the output of said first bidirectional switch 17 and, therefore, the traction command Com is applied to the output of said first bidirectional switch 17 .

[0085] Therefore, the application module 8 generates a predetermined minimum command Cmp.

[0086] If the zero speed detection module 6 generates an inactive zero speed detection signal indicating the detection of a non-zero speed of the aircraft, the second input terminal of the second bidirectional switch 18 of the disabling module 9 is connected to the output terminal of the second bidirectional switch 18, and the second input terminal of the second bidirectional switch 18 of the disabling module 9 is connected to the output terminal of the second bidirectional switch 18. Similarly, the second input terminal of the second bidirectional switch 19 of the disabling module 9 is connected to the output terminal of the second bidirectional switch 19.

[0087] Thus, if the speed of the aircraft is not zero and braking of the left-hand side is detected (i.e., if the brake detection module 7 detects that an external braking command for the left-hand side is generated), the control system 1 generates a torque command ComC1 for the drive actuators of the wheels on the left-hand side, which is equal to the predetermined minimum command Cmp. Each drive actuator on the left-hand side applies a predetermined motor torque to the associated wheel. Likewise, if the speed of the aircraft is not zero and braking of the right-hand side is detected (i.e., if the brake detection module 7 detects that an external braking command for the right-hand side is generated), the control system 1 generates a torque command ComC2 for the drive actuators of the wheels on the right-hand side, which is equal to the predetermined minimum command Cmp. Each drive actuator on the right-hand side applies a predetermined minimum motor torque to the associated wheel.

[0088] However, if the speed of the aircraft is not zero and no braking is detected (neither for the left-hand side nor for the right-hand side), the control system 1 generates a torque command ComC1 equal to the traction command Com resulting from the traction setpoint Cons generated by the pilot. Each drive actuator on the left-hand side applies a traction motor torque to the wheels, aiming to move the aircraft on the ground. Likewise, the control system 1 generates a torque command ComC2 equal to the traction command Com resulting from the traction setpoint Cons generated by the pilot. Each drive actuator on the right-hand side applies a traction motor torque on the wheels, intended to move the aircraft on the ground.

[0089] If the zero speed detection module 6 generates an active zero speed detection signal Sdv indicating the detection of zero speed of the aircraft, the first input of the second two-way switch 18 of the disabling module 9 is connected to the output of said second two-way switch 18, and therefore, the control system 1 disables the predetermined minimum command by generating a zero torque command ComC1 (equal to the zero torque command Ccn) to control each drive actuator of the wheel on the left hand side. The drive actuator of each wheel on the left hand side applies zero torque to said wheel. Likewise, the first input of the second two-way switch 19 of the disabling module 9 is connected to the output of said second two-way switch 19, and therefore, the control system 1 disables the predetermined minimum command by generating a zero torque command ComC2 (equal to the zero torque command Ccn) to control each drive actuator of the wheel on the right hand side. The drive actuator of each wheel on the left hand side applies zero torque to said wheel.

[0090] The manner in which a predetermined minimum motor torque (which is strictly positive) is defined is now described.

[0091] In this case, the electric motor of each drive actuator is a synchronous magnet motor controlled by a converter which supplies power to the phases of the motor so that the torque produced by the drive actuator corresponds to the torque command.

[0092] Park transformation is used to model the power supply to the motor. The motor is powered along the quadrature and direct axes. The direct axis corresponds to the magnetization axis of the motor's magnets.

[0093] The supply along the quadrature axis makes it possible to generate torque. The supply along the direct axis makes it possible to de-flux the motor to limit the flux of the magnets, which makes it possible to reduce the motor force of the motor and thus optimize the current size of the converter. In this case, the motor used is highly de-fluxed at high speed.

[0094] exist Figure 2 In , the operating point P of the motor is represented, and the torque generated is the traction motor torque, which is intended to move the aircraft when the aircraft is on the ground and at high speed.

[0095] The quadrature axis current Iq (axis q) enables the generation of a torque command. The quadrature axis current Iq is a positive current because the traction motor torque is a positive torque.

[0096] The direct-axis current Id (axis d), which is the high-speed demagnetizing magnetic flux, is a negative current.

[0097] It can be seen that the absolute value of the direct-axis current Id is approximately equal to twice the absolute value of the quadrature-axis current Iq.

[0098] The knowledge of the quadrature and direct axes is obtained by measuring the angular position of the motor's rotor relative to the phase of the stator (fixed in space). The measurement of the angular position of the rotor is provided by an angular position sensor, which in this case is a resolver, and makes it possible to control the motor.

[0099] However, the angular position measurement produced by the resolver includes a non-zero angular measurement error θ (also called indexing error).

[0100] like Figure 3 As shown, the real quadrature axis (real axis q) and the real direct axis (real axis d) are oriented at an angle equal to the angular measurement error θ relative to the theoretical quadrature axis (theoretical axis q) and the theoretical direct axis (theoretical axis d).

[0101] Therefore, the Iq and Id values ​​are modified and have the following characteristics:

[0102] Idreal=Idtheoretical.cosθ-Igtheoretical.sinθ

[0103] Igreal=Idtheoretical.sinθ-Igtheoretical.cosθ

[0104] Iqs is positive and Ids is negative.

[0105] Therefore, the resulting torque value is modified to be equal to the following value:

[0106] Idtheoretical.sinθ

[0107] It depends on the sign of θ. When Id is negative, if θ is positive, the generated torque is lower, and if it is negative, the generated torque is stronger.

[0108] The solution flux value itself is modified by a value equal to:

[0109] Igtheoretical.sinθ

[0110] It depends on the sign of θ. If θ is negative, this will cause strength problems.

[0111] Furthermore, it has been seen that these are the brakes of the braking system that are used when the aircraft is moving due to the taxiing system, and when the aircraft must brake. However, a residual torque equal to a predetermined minimum motor torque is maintained to maintain contact between the first and second teeth in the gear train. The minimum motor torque must be high enough to avoid entering braking mode when the pilot brakes at high speed (at a high degree of de-magnetization).

[0112] Figure 4 and Figure 5This illustrates the situation where the aircraft is at high speed during braking.

[0113] It can be seen from these figures that the applied torque is low and, by taking into account the angle measurement error, the applied torque may become negative, which would cause the drive actuator to enter braking mode (the motor is therefore a generator, which causes the above-mentioned transient power and storage problems).

[0114] To avoid this, it has been envisaged to improve the resolver to reduce the angle measurement error. It has also been envisaged to add a software reset of the mechanical mounting of the resolver in the motor. However, the risk of error is still too high, as long as the motor is highly de-magnetized, as is the case here, a few tenths of a degree are enough to substantially destroy the value of the applied torque.

[0115] Therefore, the predetermined motor torque is defined to ensure that during braking, the predetermined minimum command does not produce a negative quadrature axis current.

[0116] Therefore, the predetermined minimum command is defined such that the minimum quadrature axis current Iqmin is as follows:

[0117] Iqmin>Idmax.sin(θm),

[0118] where Idmax is the maximum demagnetizing flux current that can be applied, and where θm is the maximum angular measurement error of the resolver.

[0119] Therefore, the selected predetermined minimum motor torque inhibits operation of the generator and, therefore, inhibits recuperation of power.

[0120] In addition to the angle measurement errors, one must also add the current measurement errors (which increase the uncertainty in positioning the operating point and, therefore, also the uncertainty in the applied torque), the manufacturing tolerances of the motor (which involve more or less back EMF), the temperature of the motor's magnets and coils, the voltage of the grid (which is more or less related to the demagnetizing flux), and the varying gradient of the grid voltage (which helps to increase the margin of the demagnetizing current).

[0121] Therefore, the predetermined minimum motor torque is greater than the predetermined torque threshold, which ensures that the applied torque remains the motor torque regardless of the operating conditions of the control system.

[0122] Given these requirements, the predetermined minimum motor torque is between 400 N.m and 600 N.m, advantageously equal to 500 N.m (an equal amount is returned to the wheels). It is worth noting that, for an Airbus A320 aircraft, the maximum value of the braking torque generated by the wheel brakes can be up to (approximately) 6700 N.m to the wheels. This maximum braking torque corresponds to a value of 2400 daN, which itself corresponds to a deceleration force prohibited by the certification specification CS25.1309 above V1 during take-off.

[0123] The predetermined minimum motor torque is permanently applied, ie both when the drive actuator generates a traction motor torque and when the aircraft is braked by the braking system.

[0124] exist Figure 6 In FIG. 1 , the torque / speed characteristic 20 of each motor driving the actuator generally has a constant ordinate zone 21 at very low speeds corresponding to the take-off torque, a power limitation zone 22 and a high speed intensity zone 23. This "normal" torque / speed 20 characteristic has been modified to integrate therein a "forbidden" grey zone 24. Regardless of the speed of the aircraft, the torque generated is always greater than or equal to a predetermined minimum motor torque Cmmp, which is 500 N.m.

[0125] Naturally, the invention is not limited to the embodiments described but covers any variant coming within the ambit of the invention as defined by the claims.

Claims

1. A method for controlling a taxiing system of an aircraft, the taxiing system comprising at least one drive actuator arranged to rotate a wheel of the aircraft, the wheel also being equipped with a brake separate from the drive actuator, the method comprising the following steps: generating a traction command (Com) for controlling the motor of the drive actuator so that the drive actuator applies a traction motor torque on the wheel to move the aircraft on the ground; detecting whether an external braking command is generated, the external braking command being intended to instruct braking the wheel by the brake; If the external braking command is generated, generating a predetermined minimum command (Cmp) for controlling the electric machine so that the drive actuator applies a predetermined minimum electric machine torque on the wheel during braking, the minimum electric machine torque being strictly positive; It is detected whether the speed of the aircraft becomes zero, and if so, the predetermined minimum command (Cmp) is disabled so that the drive actuator applies zero torque on the wheel.

2. The method according to claim 1, characterized in that The predetermined minimum motor torque is defined to ensure that the predetermined minimum command (Cmp) cannot produce a negative quadrature-axis current (Iq) during braking.

3. The method according to claim 2, characterized in that The predetermined minimum command is defined so that the minimum quadrature-axis current Iqmin is as follows: Iqmin > Idmax.sin( m), Where Idmax is the maximum demagnetizing current that can be applied, m is the maximum angular measurement error of an angular position sensor of the rotor of the electric machine, the angular position sensor being used to control the electric machine.

4. The method according to claim 1, wherein: The predetermined minimum motor torque is between 400 N.m and 600 N.m.

5. The method according to any one of the preceding claims, characterized in that The external braking command is generated by the pilot of the aircraft using a brake pedal, and the detection of the generation of the external braking command comprises the steps of acquiring an estimate of the pressure on the brake pedal (Es1, Es2) and comparing the estimate of the pressure with at least one predetermined threshold (Sph, Spb).

6. A system for controlling an aircraft taxiing system, the system for controlling an aircraft taxiing system (1) being arranged to implement the method according to any one of the preceding claims, the system for controlling an aircraft taxiing system comprising: a control / command module (5) arranged to generate a traction command (Com); a braking detection module (7) arranged to detect whether the external braking command is generated; An application module (8) arranged to generate the predetermined minimum command; a zero speed detection module (6), arranged to detect whether the speed of the aircraft becomes zero; A disabling module (9) is arranged to disable the predetermined minimum command when the speed of the aircraft becomes zero.

7. The system for controlling an aircraft taxiing system according to claim 6, characterized in that: The brake detection module (7) comprises a hysteresis comparator (10, 11), comprising a first input terminal to which an estimate of the pressure on the brake pedal (Es1, Es2) is applied, a second input terminal to which an upper predetermined threshold is applied, and a third input terminal to which a lower predetermined threshold is applied, the hysteresis comparator being arranged to perform a comparison of the estimate of the pressure with the upper predetermined threshold and the lower predetermined threshold.

8. System for controlling an aircraft taxiing system according to one of claims 6 or 7, characterized in that The application module (8) comprises a first bidirectional switch (16, 17), the first bidirectional switch having a first input terminal to which the predetermined minimum command (Cmp) is applied, a second input terminal to which the traction command (Com) is applied, an output terminal, and a command input terminal to which a braking detection signal (Sdf1, Sdf2) is applied, the braking detection signal indicating a result of braking detection.

9. The system for controlling an aircraft taxiing system according to claim 8, characterized in that: The disabling module (9) comprises a second bidirectional switch (18, 19) having a first input terminal to which a zero torque command (Ccn) is applied, a second input terminal to which an output of the first bidirectional switch (16, 17) is applied, and a command input terminal to which a zero speed detection signal (Sdv) is applied, the zero speed detection signal indicating a result of zero speed detection of the aircraft.

Images