FR2491865A1 - POSITIONING OF AUTOMATIC LOCKING OF FOLDING BLADES OF HELICOPTER - Google Patents

Abstract

THE INVENTION RELATES TO AN AUTOMATIC LOCKING POSITIONING OF FOLDING HELICOPTER BLADES. THE FOLDING BLADES 12 OF THE ROTOR OF A HELICOPTER ARE AUTOMATICALLY ADJUSTED TO THE PITCH ANGLES TO WHICH THEY CAN BE LOCKED BEFORE FOLDING, BY MEANS OF CONTROL SIGNALS BY WHICH THE COMPENSATION SERVOMOTORS 39-41 AMEND 17-19 OF THE SERVO-CONTROLS 'A SWINGPLATE 13 IN THE CORRECT POSITIONS IN RESPONSE TO STORED COMPENSATION REFERENCES AND FINALLY IN RESPONSE TO THE DIFFERENCE BETWEEN THE STORED POSITIONS OF THE SERVO-CONTROLS OF THE SWINGPLATE 13 AND THE CURRENT POSITIONS 20-22 OF THESE SERVO-CONTROLS. THE INVENTION IS USED TO FACILITATE THE FOLDING OF THE BLADES OF THE HELICOPTERS SO THAT THEY CAN BE STORED IN CONFINED SPACES.

Description

249 1865

  The present invention relates to the positioning

  or setting the pitch angle of helicopter folding blades before locking them in their pitch axis so that they can be folded close to the helicopter fuselage when the helicopter is not in service; more particularly the invention relates to the automatic positioning of the pitch of the main rotor blades in order to lock them in place before

to fold them.

  In some helicopters used for specific applications, for example, helicopters having their bases on ocean-going vessels, it has long been known to fold the main rotor blades

  in positions adjacent to the fuselage of the helicopter

  when it is not in use. In this way, each helicopter can be stored more easily on a relatively small space. helicopters parked in the open are less vulnerable

gusts of wind and the like.

  In order to fold the blades, it is necessary that each of them takes a predetermined position relative to its folding joint, and vis-à-vis the fuselage of the aircraft. As a result, before folding the blades, the main rotor is indexed to a predetermined position, which has the effect of

  effect of bringing all the rotor blades into a posi-

  in which each of them can be folded into a position along the fuselage. Then> the pitch angle of each blade is adjusted to a desired position and this pitch angle is locked by means of pins, so that this pitch angle of the blades does not change subsequently when the blades are folded . As we know, we adjust the pitch of the blades

  the main rotor of a helicopter by means of rods

  pushers which are pushed against and hence

  raised and lowered by a swash plate that can

249 1865

  tilt to varying degrees in any azimuthal direction This is the inclination of the plateau

  oscillation that causes the blades to take collective

  the nominal rate at which the variable cyclic

  desired. When the blades rotate around the main rotor in flight, the push rods assembled to these

  blades and rolling on the swinging plate take

  the positions according to the inclination of the swash plate and the azimuthal position of the rotor. Therefore, it is the movement of the blades during their rotation which

  actually has the effect of varying the pace

  the current position of the swashplate. Accordingly, to adjust the pitch of the rotor blades before folding them, it is necessary to position the swash plate in the same manner as under the effect of the controls of the pilot and / or the automatic control system in flight. In the very first systems, the pitch lock pins were generally displaced by hydraulic pressure and the pitch positions of the blades were changed alternately under the action

  manual controls (for example, the joystick

  cyclic pitch control and collective pitch lever) until each blade has passed through the pitch lock. The pin could come

  cling in places thus preventing any change

  the pitch of the blade. However, the locking locking pins in flight gives rise to excessive wear. In addition, hydraulically actuated locking pins are inconvenient and do not allow for adequate design for a helicopter rotor head. On the other hand,

  pins actuated by an electric motor are

  are appropriate for the design of the rotor head, but should be allowed sufficient time for them to engage the blades

2 4918 65

  while they are kept in the proper position.

  quate. Piloting indicators should be used, indicating to the pilots the correct positions of the pitch of the blades for the engagement of the pins and the pilot should move his commands very slowly to obtain these indications and proceed to the precise adjustments of the position of step as soon as possible. that the indicators

  light up and until the pins are engaged

  elderly. A motor locking system of a modern type for folding blades is described in United States Patent Application No. 35,364 filed on May 2, 1979 in the name of Ferris and having as its

  title "BLADE POLD RESTRAINT SYSTEM".

  The invention relates to the automatic positioning of the pitch angle of the helicopter blades to facilitate the folding of these blades. Following the

  present invention in an automatic control system.

  helicopter, control signals are sent to the control servomotors.

  pitch, roll and collective pitch in order to posi-

  set the pitch angle of the main rotor blades for locking before folding. In addition, according to another embodiment of the present invention, the pitch, roll and collective pitch control signals are transmitted in

  response to stored reference values of compensa-

  of pitch, roll and collective pitch which have been determined to be correct values during a previous blade folding operation, and in response to reference values of the servocontrol positions of the swash plate, values which have also been determined to be

  correct in the course of a previous operation of re-

  folding blades. Moreover, according to the present invention

  the servo positions of the oscil-

  which have been memorized as a result of prior blade folding operation, are used as a goal to be achieved for positioning in response to pitch, roll and collective pitch control signals which have been stored at the same time. following an earlier operation of folding the blades, after which the pitch compensation control signals. roll and collective pitch are updated using an inverter mixer matrix, if this is necessary to position the swash plate as indicated by the positions of the servo controls of the latter, positions which have been stored during a

  previous operation of folding the blades.

  According to a preferred embodiment of

  the present invention in an automatic control system.

  In flight control, control signals are transmitted to the pitch> roll and collective pitch control channels of the main rotor pitch controls in response to the positions of the servo drives of the platform.

  oscillating at a moment immediately preceding the

  the blades of the helicopter, the information being stored in the form of the deviation of these positions

  compared to nominal positions which have been memorized

  in a permanent fixed memory and which must not be stored in non-volatile memory. More>

  according to the present invention, the positional movement

  of the swash plate is ensured by calculating the pitch> roll control signals and

  collective steps that must be issued to the

  geur (the latter transforming these three control signals into separate and distinct control signals relating to the front> rear and side servocontrols

  of the swash plate), so that it is not neces-

  to memorize the flight control signals used

  during a blade positioning operation to use them as a starting point in a subsequent blade folding operation. Furthermore,

  according to the present invention, an integrating

  in each of the servo control channels of the

  oscillator to determine a desired position of the latter and thereby obtain the desired pitch of the blades for locking, thereby eliminating the long-term steady-state errors that can occur in

  this position, the compensating control signals

  pitch, roll and collective pitch being emitted in response to the respective position integrators of the servo-controls of the swashplate. According to another aspect of the invention, the positioning of the pitch

  tail rotor blades (for the purpose of establishing a

  known between the rotor blades of the tail rotor and the longitudinal cyclic pitch axis (or axis of pitch) of the main rotor) is obtained in a system in which the pitch compensation position detector does not reflect a real pitch, but only the step relative to the last synchronization of the compensation position

lace movement.

  In accordance with the present invention, the pilot no longer has to continuously move the collective pitch lever and the cyclic pitch control lever until pins are randomly housed in locking members, resulting in excessive wear. Thanks to the invention, the pilot

  must no longer maintain the control levers of not col-

  Lifelike and cyclic pitch in desired positions indicated by indicator lights on the dashboard while slowly operating locking mechanisms can engage the pins. The current

  The invention makes it possible to ensure the pre-

  the pitch angle of the blades of a main rotor.

  pal so that you can use a relatively

  Slow engagement of pins without wear.

  The present invention can be implemented in a variety of ways using apparatus and techniques well known to those skilled in the art and

  light of the description below. Similarly, objects,

  features and benefits above of this

  invention, as well as others, will become clearer

  following the detailed description below

  an embodiment given by way of example with reference to the accompanying drawings in which: Figure 1 is a simplified block diagram

  a pitch control system for a helicopter's blades

  in which an automatic flight control system computer is used where the present invention can be implemented;

  FIG. 2 is a simple logic flow chart

  part of a program of a system of con-

  automatic flight control, a program in which blade folding routines can be achieved while the aircraft is on the ground;

  FIG. 3 is a simple logic flow chart

  a program of execution to control the operation of the

  operation of an automatic flight control system during blade folding operations;

  FIG. 4 is a simple logic flow chart

  folded of a background program for the folding of the blades, program from which interruptions

  calculator can reach programs that can be used

  during the implementation of this invention.

tion;

  FIG. 5 is a simple logic flow chart

  folded a program for calculating positions of folding blades;

  FIG. 6 represents a variant of the organism

  logical diagram of Figure 2 with

  in accordance with the present invention;

  FIG. 7 is a simple logic flow chart

  of a program designed to retain posi-

  locked blades for use at

249 1865

  course of subsequent blade lock operations;

  FIG. 8 represents a variant of ltorga-

  simplified logic diagram of Figure 3 with the

  Characteristics adopted according to the present invention;

  FIG. 9 represents a variant of the organism

  logical diagram of Figure 5, this variant represents

  sensing a program for calculating control signals and blade folding positions in accordance with the refinement of the present invention; and

  FIG. 10 is a simple logic flow chart

  of a program for centering the yaw movement pedals (pitch rotor pitch angle) in a system in which the position indication

  of the tail rotor is a function of the point of engagement

compensation.

  Referring now to the. In Fig. 1, a conventional helicopter having a suitable apparatus for carrying out the present invention comprises blades 12 for the main rotor, each of which blades is pivotable on a longitudinal axis in response to the position of a push rod (no shown) associated with it and which comes into contact with a swash plate 13. When the main rotor is stationary, in combination with the vertical positioning of the swash plate 13, the degree of inclination and the azimuthal tilting position of this plate determine a position for all the push rods, thus establishing a particular pitch angle for each of the

  blades. When the blades 12 of the rotor turn (the

  oscillating water never rotates), the push rods vary, in a cyclic manner, the pitch angle of each of the blades as a result of their rotation with respect to

swing plate 13.

  The swash plate 13 is connected, by a mechanical linkage 14-16, to several servocontrols 17-19 which are spaced around this plate and which, therefore, can control the positioning of

  the inclination axis, the degree of inclination and the po-

  Although the spacing of the servocontrols may vary from one case to the next, in the present example, it is assumed that the servocontrols have the following common configuration: a servocontrol 17 located at the front of the servo. rotor axis, a servo-control 18 located at the rear of the axis of the rotor and a servo-control 19 located on the side of this rotor.

  axis of the rotor, these servocontrols being called

  after respectively front servo, rear servo and side servo. "In order to obtain a

  closed-loop reaction control and in order to deter-

  undermine, by the way, the pitch angle of all the blades

  of the rotor (by determining the inclination of the

  13), the servos are

  ves, several position detectors 20-22. These detections

  position sensors can be function potentiometers

  from a regulated diet, trans-

  linear differential voltage trainers or ntim-

  what other suitable position detector is known

in the art.

  Each servocontrol 17-19 has a mechanical input member 2325 from a mixer

  26 receiving mechanical input signals 27-29 pro-

  from each of the three flight control axes, namely the pitch axis, the roll axis and the

  collective step (or axis of levitation). Following the

  licopter in which the present invention is implemented, these axes may or may not comprise

  servomotors in series. For example, the signal of

  pitch axis 27 to mixer 26 is fed from a pitch axis compensation servomotor 30 which is in series with a servo control 31, while the roll axis input signal 28 and the signal collective pitch axis input 29 are transmitted directly by corresponding servocontrols 32, 33. Similarly, the servocontrols 31-33 can

  have direct serial inputs for

  automatic flight control in the same way as with the series 30 servo

  will describe below). The servocontrols 31-33 are special

  specifically booster servocontrols with

  mechanical thrust 34-36 from both axes of a lever

  cyclic control system 37 and a control lever

  collective pitch 38 respectively. Consequently, a movement printed on one of these levers has the effect of displacing the input of the servo-control, thus hydraulically reinforcing the movement, so that one

  achieves the desired effect by applying a relative force

weakly levers 37, 38.

  The input of each servo 31-33

  has an appropriate compensating servomotor

  electrically controlled (either an electric motor or a

  hydraulic system) reacting to an electrical connection

  corresponding 42-44 from an automatic flight control computer 45. The transmission of signals

  appropriate compensation control

  connections 42-44 by the computer 45 can cause the servomotors 39-41 to adjust the pitch angle of the main rotor blades, this angle is thus set to the ground to allow the locking of the blades before folding or adjusting the flight profile of the aircraft in flight. The automatic flight check calculator may be one of the calculators disclosed in U.S. Patent Application Serial No. 938,583 filed August 31, 1978 in the name of Murphy and Clelford.

  under the title "SELECTIVE DISABLEMENT IN FAIL-OPERA-

  TIONAL, FAIL-SAFE MULTI-COMPUTER CONTROL SYSTEM ".

  calculator of this type has

  and input 46, -47 to and from a control panel 48 may include indicators 49 and switches 50 to allow the pilot to switch to the automatic flight control computer

  having the possibility to receive signals from

  emitted by inertial devices such as accelerometers and gyroscopes, as well as various position indicators. As can be seen in Figure

  1, each of the position detectors 20-22 and the detectors

  similar position sensors 51-54 (pertaining to

  servomotors and servocontrols 30-33

  can be mounted in the ECU calculator

  automatic flight control 45 at the intervention of

  corresponding connections 55. The calculator

  automatic flight control 45 can be interconnected

  with other aircraft apparatuses via multiplexed inputs and outputs including, if necessary, analog conversion, all of these features being well known in the art and described in

  the aforementioned patent application of Murphy and Clelford.

  Although not shown in more detail, the aircraft may also include a yaw movement channel 56 actuated by a servo and appropriately connected, through connections 57, to the automatic flight control computer. This channel comprises a rudder for adjusting the pitch angle of the tail rotor blades, this rudder being

  positioned by a servo control in a well known manner.

  As will be briefly described below, if the tail rotor is tilted (as described in U.S. Patent No. 4,103,848), there may be coupling between the axis of yaw movement. and the pitch axis of the helicopter, this characteristic to be taken into account during the folding operation of the blades. However, this coupling does not form part of the present invention, it constitutes a classic and known characteristic and, consequently,

  it will not be described in more detail here.

  We will describe the mode of implementation of the in-

  vention while taking. as an example, one of the automatic flight control computers described in the aforementioned Murphy and Clelford patent application. In this patent application, there are described two identical computers operating together in a particular manner; however, the use of only one of these computers to perform the functions envisaged (without intercalculator functions) will be easily understood

  reading the description below.

  In the calculator of the aforementioned patent application, all flight control functions are performed during specific interruptions. To carry out these programs, a general background program is interrupted in real time and each interruption gives rise to the execution of a particular sequence of utility programs. Programs relate

  the issuance of automatic pilot control signals

  stability control signals, compensation control signals, leverage control signals, and the like. The programs also perform many functions to determine the good operating status of each computer and the state of operation communicated to it by the other computer to determine how

  both computers can handle the workload

  vail. In one of the programs carried out in the calculation

  aforementioned, functions to be performed when

  the aircraft is on the ground, are filled in a third

  autopilot program (AP 3) which is

  FIG. 2 of the attached drawings with the modifications

  provided for the folding of the blades.

  In Fig. 2, the four-digit reference numbers are the corresponding reference numbers in Fig. 14 of the aforementioned Murphy and Clelford patent application, whereas the two-digit reference numerals are

  figures are specific to this description. In

  Figure 2, the third autopilot program is reached by a 1401 entry point and a 1402

  determines whether the particular calculator in question

  in simplex mode or not. If not, the two computers then work together and, following the paired calculator reliability system of the aforementioned Murphy and Clelford patent application, an external pitch loop computation 1403 and a

  external loop calculation of collective pitch 1404 can

  to be carried out. However, in the aforementioned patent application, if a single computer works,

  it is not allowed to perform virtual functions

  disastrous events such as the commissioning of the autopilot, so that the 1403 and 1404 calculations are derailed by an affirmative result.

  of the 1402 test. However, in a form of

  In the case of the invention in which a single computer is used, the test 1402 can be omitted, so that the programs for calculating the pitch and collective pitch loops 1403 and 1404 will always be performed. Of course, the use of a

  calculator requires other measures to

  undermine the reliability of operation. Indeed, the outer pitch loop calculation is a calculation which, with pitch output programs (of the aforementioned patent application), gives rise to the transmission of the pitch compensation control signal to the connection 42. (figure 1). Similarly, collective pitch, roll and yaw (including the 1404 external loop program and other programs of this patent application are not described here) give rise to transmission of the compensation control signals to the connections 43, 44 and 57 (FIG.

will describe it below.

  In FIG. 2, a test 1405 determines whether the

  Ronef is on the ground. The purpose of this test is to check a status indicator word or bit indicating the pressure on the helicopter wheels, rotor lock, and other factors. If the 1405 test is

  negative, the calculator can then perform

  zero commissioning 1406 grams that restore

  the zeros of different inertial sensors, this calculation

  may also perform other programs that

  are not related to the present invention.

  Then a step 1408 can transfer fault codes

  launches and error to a visualization element

  maintenance and the program is moving towards other

  through a real-time reference point 1409, triggering

  singing so the real-time interruption by which

  the third autopilot program of the fi

  step 2 is reached to return to a background program.

  All the above elements are described in much more detail in the context of a whole system of automatic flight control calculation in

  the aforementioned patent application of Murphy and Clelford.

  In FIG. 2, if the aircraft is on the ground, as indicated by an affirmative result of the test 1405, a test 60 will then determine whether the execution command of the computer is set in a blade folding mode or not. In the present example, it is believed that the blade folding embodiment includes the commissioning embodiment (as opposed to a decommissioning mode and a maintenance mode as described in the patent application). aforementioned

  Murphy and Clelford). The nature and purpose of this

  and the manner of carrying it out will be described below with reference to FIGS.

  and 4. In a first case, test 60 will be normal-

  negative manner so that the execution program 61 of the folding of the blades (which will be described below with reference to Figure 3) is achieved. Depending on the way in which the program 61 takes place, the execution mode of the calculator can switch to the mode of folding of the

  in which case program 61 will lead to a program

  In this case, the blade is folded back by triggering the real-time interruption during which the third autopilot program of FIG. 2 has been reached. Then, the computer's background program is program 62 and all the other normal functions of the calculator are reached in

  interrupting program 62 (contrary to

  when a general program of

  culator is in the commissioning mode in which

  are performed automatic tests of good function-

  such as a checksum test program and a work trial, as shown in Figure 4

  of the above-mentioned Murphy and Clelford patent application).

  In FIG. 2, if the program 61 for executing the folding of the blades does not determine that the folding operation

  the blades are ready to unfold, it will lead to

  programs, for example, ground zero programs 1407, codes sent to

  maintenance visualization 1408 and finally, the interrup-

  Real time operation via the real-time reference point 1409. Finally, the program 61 can establish the execution in the folding mode of the blades, in which case the test will be affirmative, to result in a program 63 of

  calculation of the position of folding of the blades which will be de-

  hereinafter referred to with reference to FIG. 5. This is the program that actually emits the pitch, roll and collective pitch control signals necessary to position the pitch angle of the rotor blades. principal in order to

  be able to lock them before a folding operation.

  In FIG. 3, the program 61 for performing the folding of the blades is reached by an entry point 64 and a first test 65 determines whether an indicator

  blocking validation has been set or not.

  During a first pass through the program of FIG. 3, the indicator of validation of blocking of step

249 1865

  will not normally be positioned so that a

  negative result of test 65 will reach a test 66.

* This determines if the rotor has been indexed in the desired position for locking the blades as indicated by an appropriate indicator bit and if the pilot

  operated a blade folding switch. nor-

  wrongly, llessai 66 will be negative during a first pass by the program of Figure 3. so that several pitch initiation of folding blades will be achieved one after the other until the rotor is indexed in the correct position and the pilot engaged the blade folding switch. Among the priming steps, there is a step 67 for resetting a new stored value indicator, a step 68a for resetting an indicator triggered by the positions of the swash plate, a step 68b for resetting a folding start flag (local flag only used in the program of Figure 3 as described below), as well as steps 68c, 68d for resetting a timer to seconds and a timer at 10 seconds. Then the program returns to the third pilot program

  automatic transmission of FIG. 3 via a return point 70.

  The short-term passage through the program 61 of

  the folding of the blades with only the initialization steps 67-68d will be performed each time the aircraft is on the ground unless the pilot

  decides to trigger a folding operation -in

  first dexter the rotor in the azimuth position

  correct for the folding of the blades, and then

  performing the first step proper which consists in engaging the folding switch of the blades of such

  so that the test 66 can be affirmative.

  In FIG. 3, when the test 66 is affirmed

  tif, a test 71 determines whether a local indicator of

  Folding trigger has been set or not.

  This indicator is simply intended to ensure the

  some functions once during each blade folding operation. Since the fold initiation flag is reset in test 67 during initialization before folding, the initial pass through step 71 is always negative. In this way, a test 72 is brought

  determine whether or not the pilot has engaged in

  pitch position driver which is the second stage of blade folding under pilot control. If the switch has not been engaged, a negative result of

  the test 72 will reach a step 73 which emits a signal

  indicators 49 (Figure 1) to indicate the validity of

  position position, so the pilot knows

  that the sequence has reached the stage at which it must

  set the pitch position switch to continue the blade folding operation. In this case, step 73 is the only one that must be done in

  the program for executing the folding of the blades

  during the current cycle, to return to the third pro-

  -20 gram of autopilot via the reference point 70.

  In the course of a subsequent passage by the

  In order to execute the folding of the blades, the pilot will finally engage the pitch position switch, so that step 72 is affirmative. In that case,

  a step 74 gives rise to the commitment of the com-

  thought (that is, so that the calculation

  may cooperate with compensating actuators.

  39-41 (Figure 1) to adjust the pitch position of the blades for the folding operation). Then, a step 75 returns to zero the pitch position enable flag which has been set in step 73,

  so that the pilot knows that the commitment of the

  pitch position has been identified. Likewise, a step 76 positions the fold release indicator so that, during subsequent passes by the blade folding performance program 61, the test 71 will be affirmative, thus setting the steps 73-76.

in derivation.

  In Figure 3, as soon as the indicator triggers

  When a folding test has been set, a test 77 determines whether the real-time interruption (interrupting the program to reach the third autopilot program of FIG. 2) has been triggered; if not, step 78 triggers

  the real time interruption. For this purpose, it suffices

  did just to validate all interrupts with a priority equal to or lower than the interrupts

  real time; likewise, the program will move forward

  in such a way as not to result in a return of interrup-

  tion (so that the return to the normal background program that takes place when the

  execution of the calculator is the mode of

  vice). Then, the execution program of the computer is positioned in the blade folding mode by a step 79, while the bottom program of the folding of the blades

  blades is reached by a transfer point 80.

  In Figure 4, the bottom program 62 of the replication

  The blade gap, which is reached by the transfer point, is basically a locked loop that can only work by removing the execution program out of the blade folding mode, essentially at the end of the folding operation. blades. This may occur as a result of changes in operation or due to failures that may occur

  occur or when the position function

  of the pitch of the blades of a folding operation of the latter has been performed satisfactorily

  (that is, the only function performed by calculating

  45 of automatic flight control of Figure 1 during the folding of the blades). Specifically, the bottom program 62 of the blade folding begins with a test 81 to determine if the blade folding operation is still in progress, as can be seen from the fact that the folding switch

  blades are always engaged and that the rotor is always

  days indexed. This characteristic is the same as that obtained in test 66 in FIG. 3. If the rotor accidentally deviates from its folding indexing position or if the pilot changes his mind and

  disengage the blade folding switch, a re-

  The negative result of Trial 81 will then

  gram of the bottom of the folding of the blades to a pitch 82 so as to resynchronize the compensation system with the desired compensation positions, thus eliminating any positioning of the blades that may have occurred following the execution of the programs aftercooling the blades for several cycles before the pilot changes 1S of opinion. Step 83 resets the folding indicator

  blades, a step 84 ensures the transition from the mode of

  in step-out mode, while step 85 causes the program to proceed to an initialization portion at or near that intended for power-up (which may be at either location in the 400-405 step system of Figure 4 of the application for

  patent of Murphy and Clelford), and not to

  what way appropriate to the calculator

  particular and the implementation of this

  tion. Steps 82-85 definitively put an end to the positioning operation of folding blades and they give rise to the resetting of the automatic flight control system for normal flight modes. In FIG. 4, a second trial of the bottom program 62 of the blade folding is a test 86 which determines if any of the tests that can be performed in the compensation system have failed. failure of the compensation system. If a failure has occurred in the compensation system, the test 86 will go to step 87 to set the appropriate maintenance codes, which may depend on the particular nature of the failure, the steps 82-85 terminating the folding mode of the blades as described above. Another test 88 determines whether the folding position of the blades was less than 30 seconds. If not, the positioning process has taken too much time and, therefore, it can not be completed due to some helicopter conditions outside the calculator or as a result of the calculator's inability to establish positions. correct. In this case, a negative result of test 88 will reach

  a step 89 which sets an appropriate failure code

  prayed, while steps 82-85 will put an end to

  the folding operation of the blades as described above.

  ously. In FIG. 4, the normal way out of the bottom program 62 of the folding of the blades is to perform a test 91 verifying an indicator (as described below) determining that the swash plate has been positioned within the expected tolerances and that by therefore, the positioning of the pitch angle

  blades for a folding operation of these

  has been successfully completed. An affirmative result

  Matif of step 91 results in a step 93 which sets a step-lock validation flag; it's about,

  in this case, an indicator that the posi-

  the pitch of the blades has been successfully completed, thereby triggering step

  actuate pin lock pins in order to

  hold the pitch angle set for the blades during the folding operation. Then, steps 82-85 put an end to the positioning operation of

  folding of the blades carried out by the computer.

  As soon as the bottom program 62 for folding the blades of FIG. 4 has been launched by the transfer point 80, it generally takes place in a continuous cycle by the tests 81, 86, 88 and 91, to return to the test. 81 and so on. In this case, it is a locked program loop which can only be output following the results of the tests just described or by program interrupts. Program interruptions

  are real-time interruptions bringing the program

  me from the computer to jump out of the background blade folding program and perform all normal utility programs, including the third autopilot program in Figure 2 and the programs that are reached there. Therefore, although the automatic flight control system computer is, in fact, used to transmit control signals to connections 42-44 (Figure 1) in order to activate the

  swing plate to establish the correct pitch angles

  the blades and thus allow the folding of these

  past, utilitarian programs and, in particular,

  bind, those intended for the folding of the blades, can

  all be accessible through normal interruptions.

  the real time. When these programs were

  completed in each cycle, the calculator is automatically

  re-connected to the substantive program 62 of retrospec-

  of the blades by triggering interruptions of the

  normal way. As we will see if we compare

  perfectly fits all the programs described above.

  above and below, the basic program of folding the blades has, for single function, to control whether it is desirable to maintain the execution program of the computer in the folding mode of the blades. Furthermore, this characteristic is used in the third autopilot program of FIG. 2 simply to cause the program 61 to execute the folding of the blades or the passage through the program 63 for calculating the folding position of the blades. as will be described below. Of course, we could choose other programming systems

24 918 65

  to perform similar functions using a background program or not. This characteristic, in turn, depends somewhat on the particular computer of the automatic flight control system which is used for the implementation of the present invention and

  following the technical knowledge.

  As soon as the execution program has been established in the blade folding mode by step 79 in the blade folding execution program 61 of FIG. 3, following each passage by the third autopilot program In FIG. 2, the test becomes affirmative so that, via an entry point (FIG. 5), access will be made to the program 63 for calculating the folding position of the blades. A first try 96

  determines whether position values have been initiated

  by interrogation of the resetting of the indi-

  in step 68a (Figure 3). If not, under the action of step 97, the values stored for

  pitch, roll and collective pitch references

  same as the memorized values for

  desired positions of servocontrols on the oscil-

  are read in the working part of the calculator from the non-volatile memory. These values are obtained in this non-volatile memory after a previous blade folding operation.

  as described with reference to FIG.

  Then, under the action of a series of steps 98, the pitch, roll and collective pitch reference values are used to transmit compensation control signals to the connections 42-44 (FIG. 1), these signals to be respectively equal to the stored values of pitch, roll and

  of collective steps which were determined during the

  previous ration of folding blades. Next, a step 99 sets the position-triggered indicator that has been tested in step 96 so that during subsequent passes by the calculation program 63

24918 65

  of folding position of the blades, the 97-99 steps will

put in derivation.

  If either embodiment of the invention comprises a servomotor in series such as the pitch compensation servomotor 30 (FIG. 1), it may be desirable to bring the servomotor

  known position so as to be able to repeat the position

  of the swash plate without the servomotor

  series has any adverse effect. As a result

  quence, during each passage by the program 63 for calculating the position of folding blades, a step 100

  can bring the reference value of compensation of tan-

  to be equal to the center position of the pitch compensation servomotor 30 (Fig. 1), thereby providing a simple method for utilizing the usual emission of pitch compensation control signals (as described in the aforementioned Murphy patent application). and Clelford) to center the servomotor in series in an open loop. Then, a step 101 increments the timer to 30 seconds which has been previously reset to zero in step 68c of FIG. 3. A test 102

  determines whether the timer at 30 seconds has been incremented

  to a value below its value

  maximum; if not, then we know that the cal-

  blade folding position assault was performed during many cycles during the time of 30

  seconds, indicating that there is a defect.

  As a result, a negative result of the test 102

  will lead to a step 103 which positions a fault code

  starts, then at a step 104 which provides an indication of failure to the pilot and finally at a step 105 which gives rise to the commitment of the compensation system (so that it can be resynchronized as described hereinafter by referring to FIG. 4 following an excessive time to put an end to the calculation operation of position of folding of the blades made by the computer). In this case, the program returns to the third autopilot program of the figure

2 via the transfer point 70.

  In a normal case, the time allotted to the timer at 30 seconds will not be exceeded, so that the test 102 will be affirmative, thus leading to

  a step 106 that increments a timer to 10 seconds.

  Next, a test 107 determines whether the timer at 10

  seconds has been incremented over a sufficient number of

  cycles by reaching its maximum count or not. If the 10-second timer is set below its maximum, an affirmative result from Test 107 will directly return the program to the third autopilot program via reference point 70. This provides 10 seconds during which successive cycles of the computer program can use the reference positions established in steps 98, thus giving rise to the issuance and use of compensation control signals as described above with reference to FIG. 1; therefore, the swash plate

  13 is set to the desired reference values.

  At no time will it be possible to determine whether these reference positions have been reached or not as long as the time required to reach them has not elapsed. Since the blade pitch positioning system has a response characteristic of 10% authority per second, with a 10 second time slot, the rotor blades can rotate from any step angle to a desired step angle in this 10 second time slot since we will stay within 100% of authority. Accordingly, when the 10-second timer has been incremented sufficiently to reach its maximum count, the test 107 will be negative and so a test 108 will be able to determine whether the series compensation servomotor such as a pitch compensation servomotor has achieved

249 1865

  a position equal to a stored central position.

  If not, following a negative result from

  108, the third autopilot program is taken over by the reference point 70. However, assuming that the series servomotor can be

  correctly in the 10-second time frame.

  soon or later, the test 108 will finally be

  affirmative, thus leading to steps 109 which determine

  the error between the desired positions of the servo-

  swash plate controls and the memory positions

  of these servocontrols which are thought to be correct

  to lock the blades. Then, a series of tests 110 determine whether all the errors existing in the positions of the servo-controls of the swash plate are below 0.2% o of the maximum interval of positions. If either of these errors is not within 0.2%, a negative result from one of the tests 110 will result in the correction of the position using the steps

  111 and 112. In steps 111, corrections of tan-

  pledge, roll and collective error

  underway in the individual servocontrols of the

  oscillating water (front, rear and side

  rale), are performed by a matrix whose function is the inverse of that of the mixer 26 (Figure 1). In other words, the constants K1-K9 used in steps 111 to provide the pitch, roll and collective pitch correction factors are those indicating the settings made to the pitch, roll and step control signals. collective to succeed

  at appropriate settings in the positions of the servo

  front, rear and side of the oscil-

  In view of the effect exercised by the mixer 26 (FIG. 1), transposing the control signals from the axis of the aircraft into control signals for the servocontrols of the swashplate. In this

  specification, this system will be called the "matrix of

249 1865

  In addition, by adding the fac-

  In the steps 111, steps 112 update the pitch, roll, and collective pitch values initially set in steps 98 and control the control signals to the servo motors. 39-41 compensation pitch, roll and collective pitch. Then the program can return to the third autopilot program of the figure

2 via the reference point 70.

  Finally, after several passages by the program

  If the factors to be used and all the operations of the equipment are adequate, the front, rear and lateral servocontrols of the swashplate will be positioned within 0.2%. values

  stored previously, indicating that the ver-

  rusting of the blades can take place. Consequently, the tests 110 will be affirmative and so. a step 113 will set a flag indicating that the swash plate has been positioned within the tolerances; likewise, a step 114 will provide an indication that the locking of the blades is validated, so that the

  pilot can actuate the governor insertion engines.

  locking pins of blades or other elements.

  Then we come back to the third pilot program

  automatic via the return point 70.

  In FIG. 2, at the end of each pass by the blade folding position calculating program 63, the codes of the maintenance display program 1408 and the real-time interrupt return 1409 are generated, thereby triggering the alarm. interruption of

  real time, so that the calculator returns to the

  2. Since the basic loop of the bottom program of the folding of the blades consists of only four tests, it is certain that at the normal speeds of the calculator, these four tests will all be done many times before

  the following interruption of real time brings the

  gram to subroutines resulting from interrupts.

  Therefore, it is quite certain that Trial 91 will be

  and since step 113 has positioned the

  Since the indicator states that the swashplate is within tolerances, as previously described with reference to Figure 5, this test will be affirmative. In

  Consequently, step 93 places the indicator of

  step (which is an important progression in the program as described

  below), while steps 82-85 will bring the cal-

  the culator to exit the bottom blade folding program to enter the decommissioning mode for reset. Finally, the third autopilot program of Figure 2 will be reached again during one of the real-time interruptions

  and test 60 will not be negative, so that the

  gram 61 diexecution of the folding of the blades (Figure 3) will be reached again. In this case, Figure 65 in Figure 3 will be affirmative, since the step-lock validation flag has been set in step 93 of Figure 4. An affirmative result of test 65 will result in a test. which determines whether a non-repeating local flag has been set, this flag indicating that the new values have been stored or not. Initially, test 116 will be negative, so that several tests 117-119 can be accessed to determine if all blades have

  been locked in the pitch angle. If one or the other

  tests 117-119 is negative, the calculator will return to the third autopilot program

  via point of reference 70. In subsequent passages

  by the third autopilot program (Figure 2) which leads to the program 61 for folding the blades (Figure 3), all the blades

  finally be locked, so that all

  know 117-119 will be affirmative. This will lead to a series of steps 120 giving rise to the memorization of

  existing values relating to

  pitch, roll and collective pitch, these values being used during subsequent blade folding operations, while the final positioning of the front & rear servo controls and the side of the swash plate will be memorized for use in the course of operation. a subsequent operation of folding the blades. These are the values that are accessed by step 97 in the blade position adjustment program 63 (FIG. 5). At the end of steps 120, the new stored value indicator is set in a step 121. Accordingly, during any of the subsequent passes by the blade folding performance program 61 (FIG. 3), when the indicator

  step lock validation is always posi-

  116- will be affirmative, so no function will be performed by the

folding blades.

  A system positioning the servocontrols of the swashplate by means of autopilot compensation control signals has been described.

  such that the pitch angle of the helicopter blades

  can be blocked before folding the blades.

  When the blades are locked, the autopilot compensation references that are used to operate the swash plate servocontrols are stored for use during a flight.

  subsequent operation of folding the blades, joint

  with the final positions of the servocontrols of the swash plate, positions in which the

were finally locked.

  According to the invention, an improved system automatically positioning the pitch angle of the blades

  of a rotor to validate the lock before

  folding the blades, memorizes the positions that take the servo-controls of the swashplate at the time of deployment (unblocking) of the blades, in order to use them during a subsequent operation of folding the blades. In the embodiment of the invention to be described hereinafter, no autopilot compensation reference is stored for use in subsequent pad folding operations; on the contrary, only the positions of the servo-controls of the swashplate are memorized, while the

  automatic driver compensation control signals

  that are necessary for the servo controls to reach these positions, are

  calculated from the stored positions for the services

  vocommandes. In this way, it is no longer necessary to store compensation control references in the non-volatile memory, this memory space being of high value. Furthermore, in the embodiment of the invention which will be described hereinafter, the precise information relating to the reference positions of the servo-controls of the swash plate are stored as deviations from the values

  nominal position. These discrepancies must be

  the values are, in a way, introduced into the computer because they are present in a fixed memory, this place of memory not being

no high value.

  The entire positioning for the folding of the blades that has been described with reference to Figures 2-5, takes place during the folding operation of the blades. In the embodiment of the invention which will be described below, the memorization of the positional deviations of the servocontrols takes place at a totally different moment from the use of the helicopters.

  that is at the moment when the blades must be

  bent or spread. For this purpose, the third

249 1865

  autopilot gram is modified as shown

  in Figure 6, so that there are three different methods

  Annuities that the Third Autopilot Program can be conducted while the aircraft is on the ground. Specifically, in Figure 6. When the 1405 test

  indicates that the aircraft is on the ground, test 60 may

  end if the execution program is in the blade folding mode or not. In the normal case,

  is not. This leads to a test 125 which examines

  mine an indicator bit indicating that the blades are then unlocked or not. This indicator may respond to a driver-operated deployment control switch or it may respond to another function at an appropriate time in a process of unblocking the driver.

  after redeploying them for the purpose of

  lisation. During a deployment operation, there will be a passage through the third autopilot program, during which test 125 will be affirmative. In this way, the program will move towards a program 126 for maintaining a blocking position

  This program is described below with reference to

  Figure 7. However, when the third autopilot program is reached while the aircraft on the ground is performing an operation other than

  deployment of the blades, test 125 will always be

  gatif and so, the folding execution program

  blades will be achieved in the manner described above.

  is lying. However, in the case of the form of

  of the invention which will be described below, it is necessary to provide a program 61a blade folding performance, this program is different, to

  In some respects, the implementation program for the replication

  age of the blades illustrated in FIG. 3; this program 61a

  will be described below with reference to FIG. 8.

  In FIG. 7, the program 126 for maintaining the locking positions of the blades is reached at an entry point 130. A series of steps 131 gives rise to deviations in the positions of the servocontrols

  front, rear and lateral vis-à-vis the nominal values

  the front, rear and lateral positions

  find in a fixed memory. For this purpose, the

  their indicated by the detectors 20-22 servo positions (Figure 1) are read, while the corresponding nominal values extracted from a fixed memory are subtracted. Then, in a series of tests 132-134, each of these discrepancies is checked to be certain that it is below a certain maximum tolerance. For this purpose, the absolute value of each deviation can be compared with a maximum deviation without a sign, or each deviation can be tested in order to be certain that it is neither more positive nor positive than a positive value. more negative than a negative value all this being well known in the art. If either of the deviations is excessive, a negative result of one of the tests 132-134 will result in the

  program for maintaining the locking positions of

  blades at step 135 which establishes failure codes,

  as well as at step 136 indicating that there is a defect

  in the system. However, if all the deviations are below the maximum allowable value, each of the

  tests 132-134 will be affirmative, so that we reach

  a step 137 in which a total value of

  control for deviations is calculated by summing the three gaps together. The deviations calculated in steps 131, as well as the checksum calculated in step 137 are all stored in the non-volatile memory of step 138. Consequently, these deviations will be available at a later time at which the blades must be folded, these deviations being used to calculate the compensation control signals of the automatic flight control system, these signals being necessary to reduce the pitch angle of the blades in the positions occupied by the blades when the deviations have been stored. Then a step 139 indicates

249 1865

  to the pilot that the pitch angle positions for the folding of the blades have been updated so that he can engage a switch giving rise to the execution of the following blade deployment sequence (this sequence is not part of of the present invention and

  will not be described in detail here). Then, the

  gram returns to the third pilot program

  of FIG. 6 via a reference point 140.

* When the computer passes iteratively through a third autopilot program during normal operations while the aircraft is on the ground, if the folding of the blades has not reached the stage at which the execution program of the calculator is set in a folding mode of the blades and if these are not unlocked, the test 1405 is affirmative, the test 60 and the test 125 are negative, so that the program 61a of execution of the folding of the blades is The only differences between the program 61a for performing blade folding and the program 61 for executing the folding of the blades shown in FIG.

  3, reside in the fact that the memorization of

  their intended for use in the next operation by means of the tests and steps 116-121 is eliminated, since these functions are then performed during the deployment of the blades as described with reference to FIG. 7; in addition, instead of resetting the indicator with new values stored in step 67 of FIG. 3,

  initialization consists in establishing a signal of com-

  pedal command equal to zero during an initial step

  143. The rest of Figure 8 is

  tick and performs the same function as described

  above with reference to Figure 3.

  In FIG. 8, the blade folding execution program 61a performs no function whatsoever as soon as the positioning of the pitch is completed and

249 1865

  that the bottom program 62 of the folding blades

  (Figure 4) reached step 93 by placing the indication

  validation of the blocking of steps. As a result, the test 65 (Figure 8) will always be affirmative, thus differentiating the rest of the program 6la

folding of the blades.

  During the blade folding sequence, the execution program 61a of this folding will finally reach step 79 (as described above with reference to FIG. 3), so that the execution program of the calculator is positioned in the mode

  folding blades. Then, during the passages

  by the third autopilot program in Figure 6, the position calculation program 63a

  of folding of the blades is achieved as described

  ra hereinafter with reference to Figure 9. In the form

  embodiment described here by way of example, this

  gram includes a subroutine 144 of central pedals

  as will be described below with reference to

in Figure 10.

  In FIG. 9, the program 63a for calculating the folding positions of the blades is reached by an entry point 145 and a first test 146 determines

  if the servocontrol positions of the oscil-

  were initialized or not by interrogating a

  non-repeating indicator as will be described hereinafter.

  During the first passage through the program, the result of the test 146 is negative, so that a series of steps 147 is reached, thus giving rise to the reading, from a non-volatile memory, of the positional deviations three servos and their corresponding checksum. Then, in a series of steps 148, the values of the desired positions of the front, rear and side servo controls of the swashplate are set to a value equal to the corresponding nominal positions which are provided by a fixed memory. In a test 149, the positional deviations of the servocontrols of the swashplate read in step 147 are summed and the result is compared with the checksum read in step 147 to check whether there was one or the other. Another apparent error in memorizing and extracting

  positional deviations of servocontrols of the oscil-

  lant in a non-volatile memory. If the information is still correct, the deviations are added to the desired positions in a series of steps 150. However, if the checksum test 149 indicates an error, the steps 150 are then bypassed and only the nominal values can be set. to be used as values

  desired. Following the use of the nominated positions

  the swash plate, servo-positioning

  the pitch angle of the blades near the lock position to facilitate the task of maintenance personnel performing manual

  initial operation of the calculator or after

  nance. In either case, a positive step

  the indicator triggered according to the positions of the swash plate and used in the test 146, while the indicator indicating that the swash plate is within the tolerances is reset in a step 151a. As a result, in subsequent passages by prograinnie 63a, the tests and steps 147-151a are shunted, while the program proceeds

  of the test 146 directly to a step 152 which increments

  set the timer to 30 seconds. A test 153 determines

  mine if the timer at 30 seconds has been incremented below its nominal value; if not, it means that excessive time has passed since

  first pass by the program 63a for calculating the posi-

  blade, so that a negative result from Test 153 will result in steps 154-156 which establish fault codes, indicate a failure on the dashboard and engage the system.

  compensation in order to resynchronize this

  deny when the attempt to position

  the pitch angle of the blades for folding, failed.

  If the time allotted to the timer is 30 seconds

  If it has not been exceeded, an affirmative result of the test 153 will reach a step 157 in which the 10-second timer is incremented. A test 158

  determines whether the 10-second timer has been incremented

  below its maximum value. If yes, an affirmative result from Trial 158 reaches a

  step series 158a to trigger internal registers

  scrapers to the desired positions of the servo swashplate and, therefore, to the subroutine 144 centered pedals that will be described below with reference to Figure 7. When subprogram 144 has been traveled, a series of step 159 generate the mixer inversion matrix using the

  current integrator values for servocontrols

  front, rear and side of the swash plate, thereby creating pitch, roll and collective pitch reference values which will be used by the computer to issue pitch, roll and collective pitch control signals which will be applied to the connections 42-44 (FIG. 1) of the respective compensating servocontrols 39-41 (FIG. 1). Then, the program returns to the third autopilot program via a return point 160. In subsequent passes by the chart 63a for calculating the blade folding positions, the test 158 finally indicates that more than 10 seconds since the first compensation reference values were created in step 159, which means servo controls 31-33 (FIG. 1) had 10 seconds at their

  second to reach 100% of their allowed movements

  res, so that at that moment any compensation reference value calculated in steps 159 will have to be established. When the timer at 10

249 1865

  seconds reaches a maximum, a negative result of the test 158 will result in steps 162 which compare the

  desired positions of servocontrols on the oscil-

  with their actual positions indicated by the position detectors 20-22 (Figure 1). If the oscillating plate servomotors have been positioned very close to the desired value, a series of tests 163-165 can all be affirmative. However, if

  one or the other of the position errors of the servo-

  orders exceeds 0.2% of the total posi-

  Servo control, a negative result of either of the tests 163-165 will lead to the steps 166 in which the integrators provided for the front, rear and lateral servocontrols of the tray

  are incremented by an integer constant.

  multiplication multiplied by the corresponding error. This integration is one of the characteristics of the invention and it makes it possible to avoid any long-term error (including overruns) occurring as a result of mechanical errors occurring in the control.

  and the linkages of the compensation system determine

  the servocontrol positions of the oscil-

  while also avoiding variations due to nonzero errors occurring in the yaw sensor and the positioning of the servomotors in series. During the normal course of events, following successive passages by the program 63a for calculating the positions of folding blades (which is reached by the third program of

  autopilot during successive interruptions

  real-time calculators as described above), the integrators of the swash plate servocontrols are integrated with values which,

  after the calculation (159) of the inversion matrix, furnishes

  correct references to pitch, roll

  collective action, thus bringing the system to the

  the servo controls of the swash plate. the

  249,865

  during the first ten seconds, when the steps and tests 162-166 are shunted, to be then put back into service, the program 144 centered pedals (which will be described below with reference to Figure 7) is also executed. Therefore, in the end, the pedals should be centered as described below and finally the errors should all be less than 0.2%. Therefore, an affirmative result from the three trials 163-165 will lead to a test

  168 which determines if, in fact, the pedals are cen-

  Trees. If not, the program simply leaves by way of reference point 160. However, if the pedals are centered, an affirmative result of test 168 will result in a step 169 which positions the indicator

  noting that the swash plate is within the

  rances and which is used in the background program of the folding of the blades (figure 4) in order to identify the end of the mode of folding of the blades of the calculator. Similarly, a step 170 controls the engagement of the blade locking system by indicating, to the pilot, that this

system is validated.

  In the embodiment of the invention described with reference to FIGS. 1-5 above,

  describes a simple process for centering a servo

  motor in series in an open loop in order to eliminate

  deviations in the positions of the servo-

  swash plate due to variations

  occurring in the position of this servomotor in series.

  There are other design criteria

  helicopters that can cause problems,

  which must be solved in order to ensure the position

  improvement of the pitch angle of the blades

  to the invention. For example, in the case of a

  aircraft whose tail rotor is inclined (as de-

  U.S. Patent No. 4,103,848), any variation in the speed and / or pitch of the tail rotor will influence the pitch axis.

249 1865

  of the helicopter. Consequently, there may be a coupling between the control signals of the angle of

  no tail rotor blades and

  longitudinal cyclic pitch to compensate for the effect of the tail rotor on the pitch axis. In a typical case, the coupling is designed so that no effect is exerted on the pitch axis when the tail rotor pedals are centered, while increments of positive and negative variations may be applied when the pedals

  are pushed to the right or left

  tively. As a result, the position of the centered pedals can be taken as a neutral position in that it is necessary to eliminate the coupling of the tail rotor in the pitch axis in order to be able to use the compensation system to position the angle of

  main rotor blades in accordance with the

  vention. Whenever a position detector is directly coupled to the compensation servocontrol

  yaw movement, the latter can be posi-

  in a central position and in a manner as simple as that described above

  series actuator of Figure 5. However, when

  that the position detector used to close the servo loop can be engaged in different positions to represent a selective synchronized compensation position, the

  position indicates only the relative position vis-

  with respect to any position in which the

  Compensation servocontrol has been initiated. In con-

  In sequence, the relative position detector does not indicate the location where the servo yaw compensation compensation is located. In addition, in all helicopters, a coupling is provided between the collective pitch and the pitch of the tail rotor. Another problem that may arise is the incapacity of a

  compensation system to emit a communication signal

  100% authority (from a maximum negative to a maximum positive, which is equivalent to passing from

  pedal "all left" to the pedal "all right").

  Accordingly, for the implementation of the present invention, it is necessary to resolve, to a certain extent

  measure, one or more of the problems listed above.

  According to another aspect of the invention, a subroutine 144 of centered pedals making it possible to solve the above problems is reached in FIG. 10 by an entry point 173. In this subroutine, the compensation piston of the movement of the lace is first pushed as far as the stop of

  left (if it can be), then it is brought back to

  50% of authority indicated by the detector

  relative position. In this way, we solve the problem

  the problem of non-knowledge of the position

  the actual compensation piston indicated by the

  relative position. However, if the pedals are initially brought to or near a "far right" position> the limitation of the control signal of

  compensation will prevent the transmission of a

  Mande important enough to push the pedals

  completely to the left. As a result, the sub

  program 144 detects a case in which the relative position detector indicates a relative position of

  more than 90% of full authority, while resting

  piston at 40% of full authority as indicated by

  as the relative position detector. In this way, we solve the problem that arises if we do not have full authority in the compensation channel of the yaw movement. In addition, in the subprogram

  of Figure 10, account is taken of the fact that, for

  the collective control lever equal to 50% or more, there is a coupling between this collective control lever and the stops. pedals from

  yaw, which can influence the position-

  of the pedals relative to stops and

  to be realized in the central pedal program.

  Trees. When it can be determined that the yaw-movement compensation piston has been pushed as far as possible to the left, then a 40% or 50% authority correction is used as the position-synchronization control signal to bring the pedals in the center position or

near this one.

  A first test of subroutine 144 of Fig. 10 is a test 174 for determining whether a pedal control signal has been transmitted. During the initial phases of this routine, no pedals command signal is issued, since this routine is reset to zero during the initialization step 143 (FIG. 8). As a result, an affirmative result of Trial 174 leads to the

  program that tries to bring the compensation piston

  the yaw movement completely to the left so that it can then return to the

  center using a relative position detector.

  One step 175 resets the center pedal indicator

  which is subsequently interrogated in essay 168 (Figure 9); when this subroutine has completed its task, the centered pedals indicator is set

  so that the lock validation signal

  blade can be issued. Then, a test 176 determines whether the pedal force is greater than about 1 kg; when this force reaches about

  1 kg, it is known that the spring of relaxation of the

  The compensation system is extended by the fact that the compensation piston of the yaw movement is pushed towards the extreme left. As a result, it is known that the pedals have reached a stop. Before that, a negative result of the test 176 reaches a test

  177 to determine whether the relative position of movement

  more than 90% of the total authority. If so, then we know that the zero position must

2 49 1865

  to be at or near the pedal "to the far right" and that the compensation system will not have a

  sufficient authority to bring the compensating piston

  yaw movement in the stop of the left pedal, so that no indication of a force of 1 kg will be available. If the test

  177 is negative, a synchronization control signal

  compensation for the yaw movement is issued,

  this signal being equal to an initial signal of synchronization

  compensating for yaw

  This increment is calculated to control the pedals so that they move to the left. This increment can be chosen to slowly move the pedals toward the left stop in the desired manner. Then,

  subprogram 144 returns to program 63a

  9), on the other hand, before a force of 1 kg is detected in the test 176, the relative position of the yaw movement Exceeds% full authority to the left> Essay 177 will be affirmative, so a step 180 will issue a

  pedal control signal equal to the relative position

  yaw movement less 40% of authority, thus bringing the yawing compensation piston back to the center position. Since the yaw rate compensation piston is not centered, the pitch, roll and collective pitch reference signals output in step 159 (FIG. 9) will be incorrect, so that the errors relating to swash plate servocontrols and

  occurring in step 162 will be significant.

  However, these errors will be integrated in the steps 166, so that the reference pitch, roll and collective pitch signals will finally be emitted to bring the servo-controls of the swash plate into the desired positions. Therefore, following the

  present invention, an error occurring in the center

  Pedal tread is tolerable due to

  error of the servo controls of the swashplate when issuing the compensation control signals. If, on the other hand, the force of the pedals reaches 1 kg, the test 176 will be affirmative, so that a test 181 will be reached to determine if the position of the collective control lever has been brought to a point where below 45% authority. In the

  negative, no function is performed in the sub-function

  program 144, but the program returns, via the return point 179, to the program for calculating the folding positions of the blades of FIG.

  the pitch angle of the blades so that the

  the rusting of the latter corresponds to the collective pitch control low signal, by means of the collective pitch reference signal output in step 159, the compensation system will finally bring the position of the pitch control lever below 45 % authority. When the collective step has been brought to a point below 45% of authority, an affirmative result of the test 181 will reach a step 182, thus giving rise to the transmission of a pedal command signal which is equal to the relative position of yaw movement minus 50% of yaw movement authority. Therefore, in the first part of subroutine 144 of the figure

  , we are simply trying to place the piston of movement

  yaw position in a known position to then use the relative position of yaw movement to emit a control signal returning the yaw-movement compensation piston to the center

(or near the center).

  If either of the steps 180, 182 has emitted a pedal control signal, its non-zero state will give, in test 174, a negative result which

  will reach a step 183 in which the sync signal

  compensation for the yaw movement is then set to a value equal to the command signal

  pedals that has just been issued. In one or the other

  In this case, this pedal control signal is a relative control signal of the pedals, since it is also based on the relative position detector of the yaw movement. As a result, the yaw movement compensation piston is a locked and controlled loop, which loop is closed by the relative position detector. This phenomenon is

  produced during each visit by the sub-program

  me by means of a test 184 which determines whether the relative position of yaw movement indicated at this time by the relative position detector of the yaw movement

  is within certain tolerances of synchronization

  compensating for the yaw movement that is com-

  iteratively repeated during each cycle.

  When the yaw movement relative position signal is equal to the given control signal, a step 185 sets the centered pedal indicator which is used in the position calculation program.

  folding of the blades of Figure 9. In accordance with

  Starting times and response times of the different parts of the system, the swash plate can be positioned almost correctly before centering the pedals; in this case, for the final positioning provided by the program of calculation of the positions of

  folding the blades of Figure 9v we can not remove

  that errors occur between the moment when the pedals are not centered and the one where they are centered. In other cases, the pedals can be centered long before the swash plate

  does not reach positions close to the correct setting.

  In either case, the servocontrols of the

  Oscillating water are positioned and the pedals are centered, effectively indicating that the blades have been correctly positioned by positioning, in step 169 of Figure 9, the indicator indicating that the swash plate is within tolerances. Although the invention has been illustrated and described with reference to certain exemplary embodiments, it will be appreciated by those skilled in the art that the above modifications, omissions and additions, as well as others, may be contemplated without depart from the spirit and framework of

the invention.

249 1865

Claims (5)

  1. Helicopter with main rotor   door folding blades, the pitch angles of these   can be positioned by push rods   evenings following the vertical position and inclination   a swash plate cooperating with these rods-pushing   evenings, the blades can be locked at specific pitch angles before being folded, this tray   oscillator being positioned by several servocontrols   each can work separately in response   to corresponding outputs of a mixer, this last   deny receiving, in turn, input signals from pitch, roll and collective pitch channels,   each of these channels comprising a servomotor of com-   an electrically powered design to transmit a corresponding input signal to that mixer in   response to a corresponding command command signal   thought produced by a signal processing element, characterized in that there is provided: a position detector for each of these servocontrols, each position detector emitting a signal indicating the position of a corresponding servocontrol, while the element of signal processing includes an element for storing a plurality of reference pitch, roll and collective pitch signals   relating to predetermined positions of these servo-   controls in which the pitch angle of the rotor blades is correct for locking, as well as for outputting compensation control signals to the pitch, roll and collective pitch servomotors respectively in response to these reference signals pitching, rolling and not   collective, so that the mixer brings these servo   almost in the predetermined positions   indicated by the corresponding signals relating to at servo positions.   2. Helicopter according to claim 1,   characterized in that the treatment element of   includes an element for transmitting the signals   by generating, in response to all the   desired position signals, reference signals corresponding to the compensation control signals   which will cause the compensating servomotors to emit   be input signals to the mixer, bringing   thus the servos almost in the posi-   predetermined conditions indicated by the signals relating to   at servo positions.   Helicopter according to claim 2,   characterized in that the treatment element of-si-   includes a persistent non-volatile memory and a   fixed memory, the signals relating to the desired positions   each being stored as a position signal.   the desired nominal value in this fixed memory, as well as in the form of a deviation signal indicating the deviation   between the desired position and the indi-   the corresponding signal of nominal position desired in the fixed memory.   4. Helicopter according to claim 2,   characterized in that the treatment element of   signals emits several integrator signals which are each initially equal to a corresponding desired position signal, with transmission of a plurality of error signals each indicating the positional difference indicated by one of the desired positional signals, as well as the position indicated by a corresponding signal relating to the positions of the servocontrols, each integrator signal being modified to a degree dependent on one of the error signals, while each of the reference signals is output in response to one of the integrator signals 5. Helicopter according to claim 2, characterized in that there is provided an element emitting a signal relative to the blades and indicating that the blades of the main rotor have been redeployed after being folded and they are about to be unlocked , while the signal processing element stores servo position signals as position signals   desired in response to this blade-related signal.