FR2619458A1 - CONTROL SYSTEM FOR AN ACCURATE APPROACH OF AN AIRCRAFT - Google Patents

Abstract

A precision approach control system for an aircraft during landing is disclosed. This precise approach control system transforms the cockpit control device - the joystick normally controlling the bank speed - during an engine assisted landing into a pitch angle control device. inclination of the flight path. A self-reduced throttle system for the aircraft is used to maintain the aircraft in a predetermined angle of attack during landing during the precision approach procedure.

Description

CONTROL SYSTEM FOR AN ACCURATE APPROACH OF AN AIRCRAFT

  The present invention generally relates to an approach precision control system (PAC) for stabilizing an aircraft during landing, as is the case during a relatively accurate landing on an aircraft carrier, and more particularly relates to a precision approach control system that allows the pilot to have precise control of the flight path regime and the angle of the flight path of the aircraft during landing. This approach precision control system also keeps the aircraft in a predetermined angle of attack during landing. A precise control of the flight path of an aircraft must be maintained during the entire approach procedure in the event of landing on an aircraft carrier, which is a very difficult task for a pilot. During such a landing, the pilot has a relatively narrow landing window along an ideal inclination of its trajectory. The landing is further complicated by the uncertain movements of the aircraft carrier as well as atmospheric turbulence.

and inherent to the ship.

  The landing approach of a high-performance aircraft, relatively unstable, on an aircraft carrier, is an even more difficult operation, requiring the pilot to exercise precise control of the flight path. In the prior art, stability augmentation systems (SAS), approach power compensators (APCs) and direct take-off (DLC) subsystems have been used to increase the flight qualities and also control systems, but this had been done by applying separate design criteria for each of these different subsystems. When the main objectives of these subsystems are achieved (rapid response, phugoid damping, acceleration control), the pilot has improved control over his aircraft. However, on a very high performance aircraft, relatively unstable, requiring exceptional control of the flight path, this conceptual method is generally insufficient since it does not provide precise control of the flight path.

  However, none of the previously developed approaches

  have not provided a fully satisfactory solution to the problem of providing the pilot with precise control over the flight path of an aircraft during a relatively critical landing, for example on an aircraft carrier. Aircraft manual and automatic aircraft landing (ACL) techniques, resulting from an integrated approach to the problem of flight path control, as well as the application of qualitative criteria for flight path control, have provided a better response to the flight path problem on a Grumman F-14 aircraft, requiring minor modifications to its existing architecture, as demonstrated during studies and flight simulations. The present invention relates to an approach precision control system for an aircraft during landing comprising: for an aircraft having a plurality of operational control surfaces, an autosystem for maintaining the aircraft at a predetermined angle of attack during a landing his landing; a control system for maintaining constant the angle of inertia of the flight path of the aircraft during landing; and a control device operated by the pilot for controlling the speed of the trajectory

of flight of the plane.

  The present invention provides a precision control system of the approach or a maneuvering procedure for an aircraft that allows landing of the aircraft in a more stable and easier manner than with the aid of

  already existing control systems.

  Improved aircraft control during landing should result in significantly improved flight safety, as well as significant fuel savings, as it is foreseeable that there will be fewer false maneuvers which will result in a lower number of aircraft. lower landing approaches. A lower number of landing approaches associated with a significantly greater control of the aircraft by the pilot should have the effect of reducing the number of critical flying situations, which significantly increases the safety of flight. The present invention also proposes an approach precision control system for an aircraft that essentially provides the pilot with a device for controlling the angle of flight of the flight path, said flight path angle variation regime. , being designated by (I), and by analogy hereinafter referred to as "command of the angle" or "command signal of the flight path angle" and which uses the system of self-reduction of the gases to maintain the aircraft in a predetermined angle of attack (C) thus defining the approach speed according to the weight. In an exemplary embodiment on the aircraft X-29, the control device placed in the cockpit, which is normally the joystick, is converted during the approach motorized into a control device of the angle (e) of the flight path. The precision control procedure of the approach according to the present invention provides a true control of the flight inertia trajectory and the speed of the aircraft, giving the pilot a fast and accurate control of the aircraft during flight. landing approach. The approach precision control procedure also uses the gas autoreduction control subsystem to maintain the aircraft at a predetermined angle of attack (o) during landing, which angle has been selected at 8. , 75 in a special embodiment of the invention for the X-29 aircraft, which defines the approach speed of the aircraft relative to its weight. The predetermined angle of attack (c) should normally be different for different types of aircraft and it is even possible that it

  is variable and chosen by the pilot.

  The precision control system of the approach or maneuvering procedure of the present invention is designed to allow control of the approach of an aircraft during landing to ensure a more stable flight path and procedure. landing easier, which is very important in critical landing situations such as during the landing of an aircraft on an aircraft carrier or on a runway

relatively short.

  During the maneuvering of the precision control system of the approach, when the aircraft is subjected to vertical or horizontal winds or to rotating winds, the system controls the aircraft now maintaining the angle of the aircraft's inertia trajectory. flight, which essentially defines the maneuver during the

  precision control of the approach.

  One embodiment of this approach control precision system was designed to operate on an existing aircraft, the Grumman X-29, and the particular PAC system implemented on this aircraft was using existing controls and subsystems. commanded on board this aircraft. The Grumman X-29 aircraft is designed with three pilot-operated controls, throttle, joystick and pedal controls. The suppression of the maneuver in the PAC procedure will have the effect of returning to the normal maneuver according to the approach procedure to the engine. The procedure for the precision control of the approach on the X-29 aircraft is designed so that it can be canceled by the pilot who engages the throttle control system with a force exceeding a determined threshold, for example a force greater than 35.6N In addition, the maneuvering PAC procedure is designed to be removed by closing the weighing controls on the wheels of the aircraft, indicating a landing contact. Therefore, it should be known that the maneuvering PAC procedure according to the invention can be designed to be canceled by a system.

  higher priority operational or sub-operational

system or by the pilot.

  In the embodiment of the approach precision control mounted on the X-29 aircraft, the maneuvering procedure PAC was designed to be put in place when first selecting a maneuvering procedure. normal approach, then implementing the gas self-reduction system and then the PAC procedure, all these procedures being implemented by means of normal electrical controls placed in the cockpit. For the control to be complete, several other conditions must be met, between correct predetermined limits, such as angle of attack data, altitude reference data, normal acceleration data, etc. . Then, the balancing knob is operated to stabilize the ascending (descending) plane of the aircraft, which is indicated on a needle gauge, and then, no trim balance control should be required. . This trim balance is necessary only in the example provided for the control of the X-29 aircraft, and other embodiments will not necessarily require this feature. The joystick that is normally placed in the cockpit is then maneuvered according to the PAC procedure by the pilot to control the descent speed of the cockpit.

the plane.

  The present invention for a PAC system is designed to reduce the pilot workload by reducing deviations in the flight path of the aircraft caused by atmospheric turbulence, maintaining a balanced and stable approach speed and providing optimal response to the controls of the flight path made by the pilot by means of the joystick (single command), said response characteristics being more easily perceived and planned by the pilot. This improvement in performance is obtained while taking into account acceptable transient variations of the angle of attack and maintaining the control surfaces between aerodynamic limits, allowing variations in the thrust and also during brief variations of altitude and in the presence of vibrations. The approach control precision system implemented on the X-29 aircraft automatically modulates the thrust by the throttle, in order to maintain constant the angle of attack of the aircraft and thus to maintain constant speed from the plane. This gives the pilot direct control of the angle of the flight path of the aircraft and its speed using the joystick. In addition, a vibration damping is obtained by a modulation of the thrust, which eliminates any tendency to oscillate for the flight path. Direct control of the upward movement is obtained by increasing the movement of the flap in relation to the movement of the handle, the duck canceling the helical pairs of the flap by the interconnection between the flap and the duck. Other systems such as the F-14, use spoilers to serve as a direct ascension control, which

  move at the same time as the broomstick.

  The present invention of a precision control system approaching an aircraft will be more easily

  understood with the help of the detailed description of a mode of

  preferred embodiment with reference to the accompanying drawings, in which the same elements presented in different views are designated by the same reference numerals. In these drawings: FIG. 1 is a schematic representation of an exemplary embodiment of a plane equipped with a duck, such as the Grumman X-29, which can be operated in a PAC procedure according to the teaching provided by the present invention; Fig. 2 is a functional block diagram of an external loop control system according to the present invention; and FIG. 3 is a functional block diagram of a modified PAC with a gas self-reduction system according to FIG.

present invention.

  Referring to the drawings, FIG. 1 shows an aircraft equipped with a duck, such as the Grumman X-29 aircraft, and schematically represents an aircraft having a duck control surface 2a, a control surface 2b shutter and shutter 2c, all of which are used on the X-29 jet aircraft. Controls 3 variably position the surfaces 2a, 2b and 2c. A digital flight control computer 4, of known design, has a certain number of inputs including pilot control inputs and data inputs coming from the accelerometers and gyroscopes generally designated by the numerical reference numeral 5. X-29 control system uses components and subsystems known to provide stability to a particularly unstable aircraft by means of surfaces

  subject to multiple controls.

  FIG. 1 also represents, on its right side, the X axis of the aircraft, the horizon, the aircraft speed vector V, the angle of flight path y of the aircraft and the angle of attack of the plane, all this

  being perfectly known to those skilled in the art.

  It goes without saying that the AC maneuver procedure applies to different types of aircraft other than those equipped with a duck as shown in Figure 1. In addition, the particular design of a PAC system for a particular type of aircraft will depend to a large extent on existing maneuvering and control systems already on board this aircraft and the proportion in which this design can be implemented from a

  already existing design or original design.

  The following description refers more

  particularly to a PAC system implemented on a Grumman X-29 aircraft. After the PAC procedure has been implemented, a PAC procedure indicator lights in the cockpit. If the speed stability procedure, which is part of a normal approach, has been previously selected by the pilot, the speed stability switch will turn off. If the speed stability is engaged automatically because the speed of the aircraft is less than 76,131m / s, at the moment of the selection of the PAC procedure this speed stability will also be switched off. The switch off of the PAC procedure and the return to the normal approach procedure may be achieved by exceeding the throttle reduction movement if the pilot's force exceeds 35.6 N. After this switch-off, a PAC command held by solenoid will turn off. The re-circuiting of the PAC procedure can only be implemented by the pilot himself, who will have to re-select the PAC procedure by means of the PAC command. The PAC procedure will also be shut down after the closure of an order "weighing on

wheels "exercising on the airplane.

  The operational procedure for implementing the PAC procedure is as follows; first, initiate the normal procedure / PA (flap handle in MCC, command TW = 9). Then, the supercharging and gas self-reduction control is engaged and after the PAC control. The trim trim button is then operated to suppress any movement of the pointer (h) indicating the upstroke. No control of the additional base will no longer be necessary. The desired speed for the descent and the angle of the flight path are

  controlled by the operation of the joystick.

  FIG. 2 is a block diagram of an embodiment of a control system of the outer loop approach which shows the systems controlling the control of the longitudinal surfaces. Referring to the left-hand side of FIG. 2, a control signal S of the joystick from it is multiplied at point 20 by a gravity constant G divided by the speed of the aircraft CAPV to obtain a signal GAMDL, which is then multiplied at point 22 by a constant representing the necessary gain

  with the joystick to obtain a control signal y.

  This multiplication is used because originally the joystick was sized for an increasing load factor (DNZ). A control upper branch multiplies the control signal y by a constant at point 24 to provide a direction of the signal S of

handle control.

  A DNZ signal (DNZBody cos D cos) represents a feedback signal which is also multiplied at point 26 by the same constant as at point 20 to provide a signal; real which is then added at point 28 to the control signal y. The signal; could also be obtained directly by an inertial navigation system if such a system exists on board the aircraft, the output of 28 is integrated at point 30 to obtain an integrated signal which is multiplied by a constant at point 32. The actual signal is also multiplied by a constant at point 34 to suppress vibration and provide stability. The three signals of 24, 32 and 34 are then added to point 36 to obtain a

PAC command signal.

  A signal Q representing the upward speed of the aircraft is then directed to a filter multiplier 38 which stabilizes the steady-state zero signal and the output of this signal is then multiplied by a constant at point 40 to provide a additional damping of vibrations. This output is then added to point 42 at the control signal PAC of point 36 to provide a control signal for the upward loop PAC. This signal is then applied to the existing X-29 aircraft interior control loop and this output is then

  applied to a totalizer circuit 50.

  The control signal Y of point 22 is also multiplied by a constant at point 44 and directed through a limiter circuit 46 which provides + 2 position limits providing a control signal A of the flap. The control signal A of the flap is then multiplied by a constant at point 48 to provide a DC PAC signal which is added at point 50 to the procedure signal PAC of point 42 in order to provide a signal of

order duck.

  A primary control signal from the flap coming from the pilot is then added to point 52 to the control signal, from the flap of the point 46 to provide a signal of

  total shutter control for the Grumman X-29 aircraft.

  Figure 3 is a block diagram of the X-29 modified gas handler system for the PAC maneuvering procedure. A reference signal o, representing 8.75, is added at point 60 to a signal representing the effective angle of attack of the aircraft. The resulting signal o (is multiplied by a constant at point 62 to obtain a signal K A e which is multiplied by another constant at point 64, integrated in point 66 and limited to

  point 68 to obtain a push signal TD.

  A signal DNZ is also multiplied by a constant at point 70 and then multiplied at point 72 by the cos (+ -), where o is the angle of inclination of the aircraft, the output of which is added to point 74 at the signal from point 62. The output of point 74 is then introduced through a delay filter 76 (1

  second) to produce a TE signal.

  A control signal of the handle is also multiplied by a constant at point 78, the output of this signal is introduced through a second filter 80 to provide a signal TF which is added to point 82 with the signals TD and TE in order to provide an increasing push signal. The increasing push signal is multiplied at point 84 to give an increasing signal to the engine lever. A control signal of the thrust exerted by the pilot (before the PAC) is then added to point 86 to the increasing signal of the engine and the output thereof is limited to point 88 to provide limits to the signal.

  PAC lever control at point 90 for the X-29 aircraft.

  In summary, FIG. 2 represents a block diagram of the laws governing the longitudinal controlled surfaces and FIG.

  diagram of the laws that govern the reduction of gases.

  The law that governs the whole is a command y, a

  maintenance and maintenance of the self-regulation of gases x.

  To maintain a proper speed reduction margin

  to the plane, its speed is increased on inclined routes.

  An embodiment of the present invention

  detailed description, it is

  obvious that the invention and the lessons learned from the present invention may suggest many

  variants applicable by those skilled in the art.

Claims (3)

  1.- precision approach control system for an aircraft during landing, characterized in that it comprises: on an aircraft having a plurality of operational control surfaces; an autosystem for maintaining the aircraft in a predetermined angle of attack during landing; - a control system designed to maintain constant   the angle of inertia of the aircraft's flight path   landing; and a control device operated by the pilot intended to control the regime of the flight path of the aircraft. 2.- Precision approach control system. for an aircraft according to claim 1, characterized in that   said control system comprises the joystick handle   the normal inclination during a fast-approach landing, which is converted into a control device for the speed and angle of the flight path under control. 3.- An approach control precision system for an aircraft according to claim 1, characterized in that said autosystem comprises a system for self-reduction of   gas that controls the throttle of the aircraft.