Actuating system for an aircraft
The invention relates to the field of electric actu-ating systems aboard aircrafts.
BACKGROUND OF THE INVENTION
Many systems are provided aboard aircrafts, which consist of mobile parts which have to move.
Wing elements (for example an aileron, a flap, an air brake), elements of the landing gear (for example a landing gear strut movable between an extended position and a retracted position, or a plunger of a brake of a wheel which slides relative to brake friction members), elements making it possible to implement variable geome¬try turbines, elements of a pump or a fuel metering mech¬anism, elements of the thrust reversers, elements of a propeller pitch driving mechanism (for example on an hel¬icopter or a turboprop engine), etc. belong to such mo¬bile parts.
On modern aircrafts, more and more electromechanical actuators are used to implement such mobile parts. As a matter of fact, the advantages of using electromechanical actuators are numerous: simple electric distribution and driving, flexibility, simplified maintenance operations, etc.
An electromechanical actuator conventionally com-prises a mobile actuating member which moves the mobile part, an electric motor intended to drive the mobile ac¬tuating member and thus the mobile part, and one or more sensor(s) for the various parameters of the electrome-chanical actuator.
An airborne electric actuating system wherein such an electromechanical actuator is integrated conventional¬ly implements the following functions: definition of a set-point according to the function to be fulfilled (for instance a speed, position or force set-point), measure¬ment of an electromechanical actuator servo-control pa-

rameter (for instance speed, position, force), execution of a servo-control loop enabling the electromechanical actuator to reach the set-point, generation of electric current supplying the electric motor, and transformation, by the electric motor, of the electric energy into a me¬chanical energy which drives the actuating member and thus the mobile part.
The functions of executing the servo-control loop and generating electric supply current are generally im-plemented in one or more centralized computer(s): this is called a centralized architecture.
In reference with Figure 1, a known aircraft brake 1 comprises four electromechanical actuators 2 which are grouped in two distinct arrays of two electromechanical actuators 2. The electromechanical actuators 2 of a dis¬tinct array are connected to the same centralized comput¬er 3 positioned in the aircraft bay. The electric motor of each electromechanical actuator 2 receives electric current supplying the centralized computer 3 which the electromechanical actuator 2 is connected to, and each electromechanical actuator 2 transmits measurements of a servo-control parameter to the centralized computer 3 (for instance, measurements of the angular position of the rotor of the electric motor).
Two different configurations of such a centralized architecture thus exist, which can be differentiated by the place where the set-point is defined.
In a first configuration, shown in Figure 2, means for generating the set-point 5 of each centralized com¬puter 3 define the set-point and transmit it to pro¬cessing means 6 of the centralized computer 3. The pro¬cessing means 6 of the centralized computer 3 then exe¬cute a servo-control loop. The electromechanical actuator 2 transmits the measurements of the servo-control parame¬ter obtained from a sensor 7 to the centralized computer

3, with said measurements being the servo-control loop feedback signal. The servo-control loop output signal is transmitted to a power module 8 drive, then to a power module 9 of the centralized computer 3 which generates the electric current supplying the electric motor 10 of the electromechanical actuator 2. The electric motor 10 then drives the actuating member 11. Implementing the servo-control loop requires parameters stored in a memory
12 of the centralized computer 3. The power module 9 of the centralized computer 3 is supplied by a supply unit
13 outside the centralized computer 3.
In a second configuration, shown in Figure 3, the centralized computer 3 is dedicated to the servo-control of the electromechanical actuator 2 and to the generation of the electric supply current, and it no longer defines the set-point which is supplied by another equipment 14 via a digital bus 15, for instance (the transmission is symbolized by reference Tl in Figure 3).
It should be noted that both such architecture con¬figurations have some drawbacks. The centralized computer 3 thus has to be dimensioned according to the technology of the electromechanical actuator 2 used and the parame¬ters of the servo-control loop have to be adapted to the dimensions of the electromechanical actuator 2 used. The centralized computer 3 and the electromechanical actuator 2 thus tend to be mated, which makes a modification in the electromechanical actuator 2 and a modification in the parameterization of the servo-control loop resulting from the change in technology very complex and very ex-pensive .
Besides, the electric wires between the centralized computer 3 and the electromechanical actuator 2 carry high varying current which requires complex precautions to be implemented to control the electromagnetic emis¬sions .

OBJECT OF THE INVENTION The invention aims at reducing the complexity and cost of an electric actuating system.
SUMMARY OF THE INVENTION To reach this goal, an actuating system for an air¬craft is proposed, which comprises:
- an electromechanical actuator which comprises an electric motor, a power module intended to generate a current supplied to the electric motor, measuring means adapted for measuring a control magnitude of the electro-mechanical actuator and for generating a digital measure-ment signal representative of the servo-control magni¬tude, and a non-volatile memory wherein stored data in¬cluding configuration data specific to the electromechan¬ical actuator is stored;
- a control unit intended to execute a servo-control algorithm by acquiring and using configuration data to adapt the servo-control algorithm to the electromechani¬cal actuator, with the servo-control algorithm implement¬ing a servo-control loop, the feedback signal of which is the digital measurement signal and the output signal of which is a digital signal controlling the electric motor of the electromechanical actuator intended to the power module;
- at least one data channel connecting the control unit and the electromechanical actuator and enabling the routing of the digital measurement signal, the data stored and the digital control signal.
Using the non-volatile memory positioned in the electromechanical actuator and comprising configuration data specific to the electromechanical actuator makes it possible to mutualize the control unit by using same in various electric actuating systems integrating different electromechanical actuators. The cost of such electric

actuating systems, and the complexity of said systems de-velopment, is thus reduced since it is no longer neces¬sary to totally develop a control unit for each one of said systems. Besides, designing the control unit no longer requires to know the configuration data specific to the electromechanical actuator used (and even no long¬er requires to know the technology specific to the elec-tromechanical actuator used). The interactions required between the development activities of the control unit and the electromechanical actuator are thus reduced, and the complexity of such development, and therefore the cost of the electric actuating systems is reduced again.
Other characteristics and advantages of the inven¬tion will become apparent upon reading the following de-scription of particular non-restrictive embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference is made to the appended drawings, wherein:
- Figure 1 shows a braking system architecture of the prior art;
- Figure 2 shows a first actuating system of the prior art;
- Figure 3 shows a second actuating system of the prior art;
- Figure 4 shows a braking system architecture of a system according to a first embodiment;
- Figure 5 shows a braking system architecture of a system according to a second embodiment;
- Figure 6 shows an actuating system according to a first embodiment of the invention;
- Figure 7 shows an actuating system according to a second embodiment of the invention;
- Figure 8 shows an actuating system according to a third embodiment of the invention;

- Figure 9 shows an actuating system according to a fourth embodiment of the invention;
DETAILED DESCRIPTION OF THE INVENTION
The invention is implemented here on an aircraft which comprises a plurality of main landing gears each carrying a plurality of so-called "braked" wheels, i.e. a plurality of wheels equipped with a brake intended to brake the aircraft. The present description relates to a single braked wheel, but the invention of course applies in the same way to all or part of the braked wheels of the aircraft or to any other device of an aircraft or the motorization thereof implementing an electromechanical actuator.
In reference to Figure 4, a braking system architec-ture according to a first embodiment thus comprises a brake 20 intended to brake a wheel of the aircraft, a first supply unit 21a, a second supply unit 21b, a first control unit 22a, a second control unit 22b and a network switch 23.
The brake 20 comprises an actuator-holder whereon four braking electromechanical actuators 25a, 25b, 25c, 25d and friction members, i.e. a stack of carbon disks are mounted.
The four electromechanical actuators 25 are used to apply a braking force onto the stack of carbon disks and thus exert a braking torque onto the wheel which slows down the rotation of the wheel and thus slows the air¬craft down when the latter touches the ground.
Each electromechanical actuator 25 comprises a body attached to the actuator-holder, a plunger and a locking member adapted for locking the plunger in position. An electric motor, a power module and a digital communica¬tion module 2 6 are integrated into the body of each elec-tromechanical actuator 25.
The plunger is actuated by the electric motor to

slide and apply the braking force onto the stack of car¬bon disks.
The power module makes it possible to generate an alternating supply current which circulates in three phases of the electric motor when the plunger has to be actuated to brake the wheel. For this purpose, the power module comprises an inverter comprising a plurality of switches which are so controlled as to transform a direct supply voltage Vc into an alternating voltage at which the current supplying the electric motor is generated.
The supply voltages Vc received by the power modules of the four electromechanical actuators 25 of the brake 20 are delivered by the first supply unit 21a and the se¬cond supply unit 21b.
The four electromechanical actuators 25 are grouped into a first array and a second distinct array, with the first array comprising the electromechanical actuators 2 5a and 25b and with the second array comprising the electromechanical actuators 25c and 25d.
The-first supply unit 21a supplies the supply volt¬age Vc to the power modules of the electromechanical ac¬tuators 25a and 25b of the first array, whereas the se¬cond supply unit 21b supplies the supply voltage to the power modules of the electromechanical actuators 25c and 25d of the second array.
To receive the supply voltage Vc, each electrome-chanical actuator 25 is connected to the first supply unit 21a or to the second supply unit 21b by two power supply wires 28.
The first supply unit 21a and the second supply unit 21b are placed in the bay, in the aircraft fuselage, above the landing gear.
Besides, the power module of each electromechanical actuator 25 uses a digital control signal Sc to control the inverter switches.

The digital control signals Sc of the four electro¬mechanical actuators 25 are generated by the first con¬trol unit 22a and by the second control unit 22b.
This time, each control unit 22 generates digital control signals Sc to be sent to the four electromechani-cal actuators 25. The first control unit 22a and the se¬cond control unit 22b are thus redundant, so that the loss of one of the two control units 22 does not affect the braking performances.
The first control unit 22a and the second control unit 22b are placed in the bay, in the aircraft fuselage, above the landing gear.
The distribution of the digital control signals Sc to the power modules of the four electromechanical actua¬tors 25 is executed via the digital communication modules 2 6 of the four electromechanical actuators 25, with each digital communication module 26 of one electromechanical actuator 25 transmitting to the power module and thus to the inverter of the power module of said electromechani¬cal actuator 25 the digital control signals Sc which are to be sent thereto.
The digital communication modules 26 of the four electromechanical actuators 25 are interconnected to form a digital network 30 (digital network means, here, an as-sembly of interconnected communicating devices exchanging data as digital signals) . The digital network 30 is here ring-shaped.
The network switch 23, which is connected to the first control unit 22a and to the second control unit 22b, is integrated in the digital network 30.
The network switch 23 is thus connected to the digi-tal communication modules 26 of two electromechanical ac-tuators 25 of the brake 25a and 25c, so as to build, too, one of the entities forming the closed loop of the ring-shaped digital network 30, with the digital communication

modules 26 of the four electromechanical actuators 25 building the other entities. Each entity (the digital communication module 26 or the network switch 23) of the digital network 30 is connected by four communication electric wires 32 to two distinct entities.
The network switch 23 manages the operation of the digital network 30 by distributing the digital control signals Sc from the first control unit 22a and the second control unit 22b to the digital communication modules 26 via the digital network 30.
The network switch 23 is here positioned with the first control unit 22a and with the second control unit 22b in the same box (which is thus placed in the bay, in the aircraft fuselage, above the landing gear).
The transmission to the digital communication mod¬ules 26 and thus to the power modules of the digital con¬trol signals Sc from the control units 22, and the supply of the power modules with the supply voltage Vc from the supply units 21 thus reguire sixteen electric wires which run from the top of the landing gear to the brake 20, in¬stead of the twenty-eight electric wires of the architec¬ture of Figure 1.
It should be noted that the digital network 30 which has just been disclosed is not used for transmitting the digital control signals Sc to the power modules of the electromechanical actuators 25 only.
The uplink digital signals Sm are also transmitted from the brake 20 to the control units 22 via the digital network 30 and thus via the network switch 23.
The uplink digital signals Sm firstly comprise digi-tal measurement signals emitted by the digital communica-tion modules 26 and emitted by sensors integrated in the electromechanical actuators 25. The measurement digital signals are here signals for measuring the angular posi¬tion of the rotors of the electric motors, signals for

measuring the currents supplying the electric motors, and signals for measuring the force produced by the electro¬mechanical actuators 25 actuating member.
The angular position measuring signals are emitted, for each electromechanical actuator 25, from an angular position sensor integrated in said electromechanical ac¬tuator 25.
The angular position measuring signals are emitted, for each electromechanical actuator 25, from a current sensor integrated in said electromechanical actuator 25.
The force measuring signals are emitted, for each electromechanical actuator 25, from a force sensor inte¬grated in said electromechanical actuator 25.
The angular position, current and force measuring signals are digitalized by the communication modules 2 6, emitted on the digital network 30 and used by the control units 22 for generating the digital control signals Sc and controlling the electric motors of the four electro-mechanical actuators 25.
The uplink digital signals Sm then comprise electro-mechanical actuators 25 monitoring signals emitted by the digital communication modules 26.
The electromechanical actuators 25 monitoring sig¬nals are intended to supply a state of the electromechan¬ical actuators 25 from which the control units 22 may make the decision to order a maintenance operation, or to totally or partially deactivate one or more electrome¬chanical actuator(s) 25.
Eventually, the uplink digital signals Sm comprise measurement signals transmitted to the electromechanical actuators by an external sensor positioned on the wheel (not shown in Figure 4) . The external sensor is here a brake torque sensor positioned on the brake 20. The ex¬ternal sensor is integrated in the digital network 30 (it also forms one entity of the ring digital network) . It

comprises a digital interface which, like the digital communication modules 26 mentioned above, enables the ex-ternal sensor to transmit the torque measurements to the control units 22 via the digital network 30.
Besides, in addition to the digital control signals Sc, additional downlink digital signals Sd are transmit¬ted from the control units 22 to the brake 20 via the digital network 30.
The additional downlink digital signals Sd firstly comprise electromechanical actuators 25 functional test signals and sanction signals.
The functional test signals trigger the execution of functional tests by the electromechanical actuators 25 with a view to making a diagnosis relating to the opera¬tion of the electromechanical actuators 25 {and, option¬ally, relating to the efficiency of communications from and to the electromechanical actuators 25).
The sanction signals enable the control units 22 to "penalize" an electromechanical actuator 25 by totally or partially deactivating same, or by excluding the digital communication module 26 thereof from the digital network 30.
The additional downlink digital signals Sd also com-prise signals for controlling another equipment mounted on the wheel, i.e. here a brake fan 20 (not shown in Fig¬ure 4). The brake fan 20 is integrated in the digital network 30 (it also forms one entity of the ring digital network). It comprises a digital interface which, like the digital communication modules 2 6 mentioned above, en¬ables the brake fan 20 to receive the control signals from the control units 22 via the digital network 30.
In the braking system architecture according to a second embodiment, shown in Figure 5, the digital net¬work, this time, is a star digital network 4 0.
The network switch 23 forms a node of the digital

star network 40 which all the electromechanical actuators 25 of the brake 20 are connected to.
It should be noted that the braking system architec-ture according to the second embodiment comprises, in ad-dition to the four electromechanical actuators 25, the power supply units 21, the two control units 22 and the network switch 23, a connexion box 41 mounted on the brake actuator-holders 20.
The four electromechanical actuators 25, the two power supply units 21, the two control units 22 and the network switch 23 are connected to the connexion box 41.
The connexion box 41 receives the continuous supply voltage and the downlink digital signals mentioned above, and distributes same to the electromechanical actuators 25 and to the brake torque sensor and to the brake fan. The connexion box 41 also receives the uplink digital signals mentioned above, and distributes same to the net-.work switch 23 which transmits same to both control units 22.
Advantageously, whatever the embodiment of the brake system architecture, the locking member of each electro¬mechanical actuator 25 is integrated too in the digital network 30 or 40. The locking member is then locally sup¬plied from the supply voltage received by the electrome-chanical actuator 25 and issued by one of the supply units 21. The locking member receives control orders via the digital network 30, 40 and emits a status on the dig¬ital network 30, 40.
The way each control unit 22 controls one of the four electromechanical actuators 25, and thus generates the digital control signals Sc to be sent to such elec-tromechanical actuator 25 will now be described in great-er details.
Referring to Figure 6, it is considered that one of the two control units 22 and one of the four electrome-

chanical actuators 25 form an actuating system according to a first embodiment of the invention which, in addition to the control unit 22 and the electromechanical actuator 25, comprises a digital transmission channel 50 which connects the control unit 22 and the electromechanical actuator 25. The following also applies to both control units 22 and to the four electromechanical actuators 25 described above.
In the braking system architectures of Figures 4 and 5, the digital transmission channel 50 consists of the electric wires connecting the control unit 22 with the network switch 23, through the network switch 23, through the connexion box 41 as regards Figure 5, and through the various elements of the digital network (electric wires, communication modules 2 6 of other electromechanical actu-ators 25) which separate the digital communication module 26 of the electromechanical actuator 25 involved from the network switch 23.
The control unit 22 comprises set-point generating means 51, processing means 52, and a digital communica¬tion interface 53.
As seen above, the electromechanical actuator 25 comprises a communication module 26, a power module 54, an electric motor 55, a plunger 56 and measuring means 59 comprising sensors (for example a current sensor, an an¬gular or linear position sensor, a force or torque sen-sor) . The power module 54 comprises an inverter control 57 and an inverter 58.
Additionally, the electromechanical actuator 25 com-prises a non-volatile memory 60 wherein stored data 61 including configuration data 62 specific to the electro¬mechanical actuator is stored.
The configuration data 62 comprises servo-control parameters 63 specific to the electromechanical actuator 25, the function of which is explained hereunder.

The non-volatile memory 60, programmed during the manufacturing of the electromechanical actuator 25, is compatible with the environmental conditions (tempera-ture, vibrations, shocks, electromagnetic perturbations, etc. ) which the electromechanical actuator 25, which is mounted on a brake actuator-holder, is exposed to. The non-volatile memory 60 is advantageously integrated in a semi-conductor component of the digital communication module 26.
The angular position measured by the angular posi¬tion sensor of the electromechanical actuator 25 and the current measured by the current sensor of the electrome¬chanical actuator 25 are servo-control magnitudes of the electromechanical actuator 25.
The measuring means 59 convert the measured servo-control magnitudes into digital measurement signals rep¬resentative of the servo-control magnitudes.
To control the electromechanical actuator 25, the processing means 52 of the control unit 22 execute a ser-vo-control algorithm 67, the native code 65 of which is stored in a memory 66 of the processing means 52.
The servo-control algorithm 67 implements three in¬terleaved servo-control loops intended to control the power module 54 of the electromechanical actuator 25 via the digital channel 50: a current servo-control loop, a speed servo-control loop and a position servo-control loop.
The set-point of each servo-control loop is a set-point generated by the set-point generating means 51 of the control unit 22 or another control unit of the air-craft .
The feedback signal of the current servo-control loop is the digital measurement signal representative of the current, and the feedback signal of the speed and po¬sition servo-control loops are the digital measurement

signals representative of the angular position. The feed-back signals are transmitted by the communication module 2 6 of the electromechanical actuator 25 to the control unit 22 via the digital transmission channel 50 (trans¬mission T2 in Figure 6).
The output signal of the servo-control algorithm is an electric motor control digital signal 55 to be sent to the power module 54 (transmission T3 in Figure 6).
The digital control signals are transmitted to the power module 54 of the electromechanical actuator 25 via the digital interface 53 of the control unit 22, the dig-ital transmission channel 50 and the digital communica¬tion module 26 of the electromechanical actuator 25 (transmission T3 in Figure 6). The inverter control 57 of the power module 54 then controls the inverter 58 which generates a current supplied to the electric motor 55 to drive the plunger 56 of the electromechanical actuator 25 according to the set-point.
Implementing the servo-control loops uses the servo-control parameters 63 specific to the electromechanical actuator 25, which comprise, here, a proportional coeffi¬cient, an integral coefficient and a derived coefficient, and a position limitation, a speed limitation and a power limitation of the electromechanical actuator 25.
Prior to using the electromechanical actuator 25, for example upon starting the control unit 22 and the electromechanical actuator 25, the processing means 52 of the control unit 22 thus acquire the servo-control param-eters 63 stored in the non- volatile memory 60 of the electromechanical actuator 25 and integrate same into the servo-control loops (transmission T4 in Figure 6) . The processing means 52 then have all data required for exe¬cuting the servo-control algorithm 67 and the servo-control loops.
Any modification in the design of the electromechan-

ical actuator 25 requiring a modification in the servo-control parameters 63 specific to the electromechanical actuator 25 can thus be implemented by storing the new servo-control parameters 63 in the non-volatile memory 60 of the electromechanical actuator 25 only, and thus with¬out modifying the control unit 22. The costs entailed in the modification in the design of the electromechanical actuator 25 are thus reduced.
Referring to Figure 7, the actuating system accord¬ing to a second embodiment of the invention again com¬prises the control unit 22, the electromechanical actua¬tor 25 and the digital transmission channel 50.
The non-volatile memory 60 of the electromechanical actuator 25 of the system according to the second embodi-ment of the invention is also used for parameterizing other algorithms.
The configuration data 62 among the stored data 61 stored in the non-volatile memory 60 comprises, in addi¬tion to the servo-control parameters 63 of the servo-control algorithm 67, parameters 70 of a failure detec¬tion algorithm 71 and/or a trend following algorithm 72 and/or a cycle counting algorithm 73.
The failure detection algorithm 71, the trend fol-lowing algorithm 72 and the cycle counting algorithm 73 are stored in the memory 66 of the processing means 52 of the control unit 22. When one of these algorithms 71, 72, 73 has to be executed, the control unit 22 acquires the corresponding parameters 70 (transmission T5 in Figure 7) .
Referring to Figure 8, the actuating system accord¬ing to a third embodiment of the invention again compris¬es the control unit 22, the electromechanical actuator 25 and the digital transmission channel 50.
The non-volatile memory 60 of the electromechanical actuator 25 of the actuating system according to the

third embodiment of the invention is also used for stor¬ing an identifier 80 of a servo-control algorithm to be used for the electromechanical actuator 25.
The configuration data 62 among the stored data 61 stored in the non-volatile memory 60 comprises an identi-fier 80 which enables the processing means 52 of the con-trol unit 22 to select the servo-control algorithm to be used among a list of servo-control algorithms stored in the memory 66 of the processing means 52.
The list of servo-control algorithms comprises a servo-control algorithm 81 for an electromechanical actu-ator with an alternating current motor, a servo-control algorithm 82 for an electromechanical actuator with a di-rect current motor, a servo-control algorithm 83 for an electromechanical actuator with a torque motor, a servo-control algorithm 84 for an electromechanical actuator with a step motor.
The electric motor 55 of the electromechanical actu-ator 25 is here an alternating current motor. Prior to using the electromechanical actuator 25, for example upon starting the control unit 22 and the electromechanical actuator 25, the processing means 52 of the control unit 22 thus acquire the identifier 80 stored in the non¬volatile memory 60 of the electromechanical actuator 25 (transmissions T6 and T6'1 in Figure 8). The processing means 52 select and then execute the servo-control algo¬rithm 81 for an electromechanical actuator with an alter¬nating current motor.
Changing the technology of the electric motor 55 of the electromechanical actuator 25 which requires using a different servo-control algorithm previously stored in the memory 66 of the processing means 52 can thus be im¬plemented by storing the new identifier in the non¬volatile memory 60 of the electromechanical actuator 25 only, without modifying the control unit 22.

Referring to Figure 9, the actuating system accord¬ing to a fourth embodiment of the invention again com¬prises the control unit 22, an electromechanical actuator 25 and a digital transmission channel 50.
The non-volatile memory 60 of the electromechanical actuator 25 of the system according to the fourth embodi-ment of the invention is also used for storing a native code 90 of an already parameterized servo-control algo¬rithm of the electromechanical actuator 25.
Prior to using the electromechanical actuator 25, for example upon starting the control unit 22 and the electromechanical actuator 25, the processing means 52 of the control unit 22 thus acquire the native code 90 of the servo-control algorithm in the non-volatile memory (transmissions T7 in Figure 9).
Designing the control unit 22 thus does not require a previous definition of the servo-control algorithm.
It should be noted here that the native code of any type of algorithm can be stored in the non-volatile memory 60 and not only the native code of a servo-control algorithm (for instance, the native code of a failure de¬tection algorithm and/or a trend following algorithm and/or a cycle counting algorithm).
Advantageously, and whatever the embodiment of an actuating system disclosed above, the non-volatile memory 60 of the electromechanical actuator 25 can be used to store configuration data comprising electromechanical ac¬tuator 25 calibration data. The calibration data can be used by the control unit 22 to correct one or more set-point (s) of the servo-control loops or the digital meas¬urement signals. The calibration data is, for example, data enabling a gradient correction, an offset correction or a correction according to the parameters measured by the sensors of the electromechanical actuator.
Storing the calibration data in the non-volatile

memory 60 of the electromechanical actuator 25 makes it possible to simplify the development of the electrome-chanical actuator 25 during the designing and the manu-facturing thereof, and thus to reduce the design and pro-duction costs of the electromechanical actuator 25. Be-sides, the system performances are enhanced when cali-brating the electromechanical actuator 25 using the cali-bration data.
Whatever the embodiment of the actuating system de¬scribed above, the non-volatile memory 60 may advanta¬geously contain data supplied by the control unit 22. The non-volatile memory 60 is then read-accessible and/or write-accessible by the control unit 22. The stored data is routed between the electromechanical actuator 25 and the control unit 22 on the transmission channel 50, what¬ever the routing direction.
The data supplied by the control unit 22 here com¬prises information on the utilization of the electrome¬chanical actuator 25, which is produced from other data stored in the non-volatile memory 60 of the electrome¬chanical actuator 25, or which is obtained when the con¬trol unit 22 executes any algorithm.
Storing the utilisation information relative to the electromechanical actuator 25 in the non-volatile memory 60 thereof facilitates the future maintenance operations. A maintenance operator will have access to the infor¬mation on the utilisation of the electromechanical actua¬tor 25 without it being necessary to configure the con¬trol unit 22 or the electromechanical actuator 25 accord¬ing to a specific maintenance configuration. Additional¬ly, the future repair operations are facilitated. A re¬pair operator will have access to the information on the utilisation of the electromechanical actuator 25 without it being necessary to transfer data from the control unit 22.

Whatever the embodiment of the actuating system de¬scribed above, the non-volatile memory 60 may advanta¬geously contain other information used by the servo-control algorithm, for monitoring, maintenance, produc¬tion and delivery of the electromechanical actuator 25. Among such information, the reference or the serial num¬ber of the electromechanical actuator 25 can be cited.
Such information can specifically be used during the initialisation phase of the electromechanical actuator 25.
Whatever the embodiment of the actuating system de¬scribed above, the data stored 61 in the non-volatile memory 60 is advantageously protected by a checking tool of the cyclic redundancy check type which ensures the in-tegrity of the stored data 61 and the detection of cor-ruption of such stored data.
Whatever the embodiment of the actuating system dis-closed above, the transmission channel 50 advantageously consists of a fast channel and a slow channel.
The digital data which requires a fast transmission (like a real-time transmission) is routed on the fast channel. This more particularly relates to the digital control signals and the digital measurement signals used in the servo-control loops.
The digital data which does not require a fast transmission is routed on the slow channel. This more particularly relates to the stored data 61 of the non-volatile memory 60 upon writing or reading such stored data 61.
The stored data 61 may further be read-accessible and/or write-accessible by a wireless interrogation de¬vice using RIFD-type technology. Such wireless access is particularly interesting when carrying out maintenance operations on the electromechanical actuator 25.
The communication module and/or the power module are

advantageously integrated in the same ASIC which may be developed for several types of electromechanical actua-tors, which reduces the so-called « not recurrent » de-velopment costs of such electromechanical actuators.
Of course, the invention is not limited to the spe¬cific embodiments described above, but on the contrary, encompasses any alternative solution within the scope of the invention as defined in the claims.
Although the external sensor is mentioned to be a braking torque sensor positioned on the brake, providing one or more different external sensor(s) can be consid¬ered, for instance a disk stack temperature sensor (typi¬cally a thermocouple), or a wheel tyre pressure sensor, or still a tachometer.
Although the actuating system of the invention has been described within an architecture of the braking sys-tem, the actuating system of the invention can be inte-grated in the architecture of another type of system: a propulsion system, a flight controls system, a landing gear system, a thrust reverser control system, a wing el¬ements control system, etc.
Although the electromechanical actuator disclosed here has a specific architecture, the latter may of course be different. The invention may for instance be applied to an actuating system comprising an electrome¬chanical actuator having two different redundant chan¬nels, with each channel having its own communication mod¬ule, its own power module, and if need be its own engine and its own actuating member. Each channel is also asso-cialed with different configuration data, in order to im¬plement different servo-control algorithms.
The digital transmission channel disclosed here is relatively complex, because of the array arrangement of the electromechanical actuators. The invention can of course be applied to an actuating system comprising a

different digital transmission channel, such as a simpl digital bus.

WHAT IS CLAIMED IS:
1. Actuating system for an aircraft comprising:
- an electromechanical actuator (25) comprising an electric motor (55), a power module (54) intended to gen-erate a current supplied to the electric motor, measuring means (59) adapted for measuring a servo-control magni¬tude of the electromechanical actuator and for generating a digital measurement signal representative of the servo-control magnitude, and a non-volatile memory (60) wherein stored data (61) including configuration data (62) spe¬cific to the electromechanical actuator is stored;
- a control unit (22) intended to execute a servo-control algorithm by acquiring and using configuration data to adapt the servo-control algorithm to the electro¬mechanical actuator, with the servo-control algorithm im¬plementing a servo-control loop the feedback signal of which is the digital measurement signal and the output signal of which is a digital signal controlling the elec¬tric motor of the electromechanical actuator intended to the power module;
- at least one digital transmission channel (50) con¬necting the control unit and the electromechanical actua¬tor and enabling the routing of the digital measurement signal, the stored data and the digital control signal.

2. A system according to claim 1, wherein the configuration data comprises parameters (63) of the ser¬vo-control algorithm.
3. A system according to claim 2, wherein the parameters (63) comprise a proportional coefficient and/or an integral coefficient and/or a derived coeffi¬cient of the servo-control loop, and/or a position limi¬tation and/or a speed limitation and/or a power limita¬tion of the electromechanical actuator.
4. A system according to claim 1, wherein the

configuration data (62) comprises parameters (63) of an¬other algorithm.
5. A system according to claim 4, wherein the other algorithm comprises a failure detection algorithm and/or a trend following algorithm and/or a cycle count¬ing algorithm.
6. A system according to claim 1, wherein the configuration data (62) comprises an identifier (80) ena-bling the control unit to select the servo-control algo¬rithm to be used among a list of servo-control algorithms stored in the control unit.
7- A system according to claim 1, wherein the configuration data comprises a native code of the servo-control algorithm.
8. A system according to claim 1, wherein the configuration data comprises electromechanical actuator calibration data.
9. A system according to claim 8, wherein the calibration data comprises a native code of a calibration algorithm.
10. A system according to claim 9, wherein the calibration algorithm is a gradient correction and/or an offset correction and/or a correction according to a pa¬rameter measured in the electromechanical actuator, such as temperature.
11. A system according to claim 1, wherein the stored data further comprises data transmitted by the control unit.
12. A system according to claim 11, wherein the data Iransmilted by the control unit comprises infor¬mation on the utilization of the electromechanical actua¬tor.
13. A system according to claim 1, wherein the stored data is protected by a checking tool of the cyclic redundancy check type.

14. A system according to claim 1, wherein the electromechanical actuator comprises two redundant chan¬nels which different configuration data is associated with, in order to implement different servo-control algo-rithms .
15. A system according to claim 1, wherein two digital transmission channels connect the control unit and the electromechanical actuator.
16. A system according to claim 15, wherein both digital transmission channels comprise a fast channel for exchanging the digital measurement signal and the digital control signal, and a slow channel for transmitting the stored data.
17. A system according to claim 1, wherein some of the stored data is read-accessible and/or write-accessible by a wireless interrogation device using R1FD-type technology.