Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
  • G01C23/00—Combined instruments indicating more than one navigational value, e.g. for aircraft; Combined measuring devices for measuring two or more variables of movement, e.g. distance, speed or acceleration
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
  • G05D1/00—Control of position, course, altitude or attitude of land, water, air or space vehicles, e.g. using automatic pilots
  • G05D1/02—Control of position or course in two dimensions
  • G05D1/0202—Control of position or course in two dimensions specially adapted to aircraft

Definitions

• the invention relates to an on-board method and device for assisting the navigation of an aircraft.
• the field of the invention is that of aid to navigation and air safety and more particularly relates to aid for the alignment of an aircraft on a predetermined trajectory such as for example an approach trajectory.
• the trajectory to be captured is also designated by the trajectory on which the aircraft must align; it is a priori a trajectory that does not change or little during the capture. Subsequently, we consider more particularly ground trajectories, that is to say projections on the ground of the trajectories of aircraft.
• the trajectory 1 to be captured in order to land on a runway 5 is displayed on the navigation screen 4 of the airplane which is itself schematically represented on the screen under the reference 3. It is a 1-track trajectory comprising 2 altitude or control point marks, sent by an air traffic controller at the airport. As the airplane 3 progresses, this trajectory 1 ground scrolls under the airplane located in the center of the navigation screen 4 and whose heading is marked in degrees (275 ° in the case of the figure ). To avoid overloading the figure, the measurements provided by the aircraft sensors and which are displayed on this navigation screen are not shown.
• this trajectory does not travel exactly under the airplane, in particular when the very position of the airplane is not displayed on the navigation screen with sufficient precision. This may be the case when the means of calculating and / or displaying the trajectory of the airplane which are on board the aircraft are insufficiently precise.
• this trajectory does not pass under the plane because the plane is not aligned on it in particular because of the wind which deports the plane and prevents it for example from respecting the planned turn.
• the airplane 3 controlled by the pilot can then capture this trajectory 1 further on at the end of a trajectory 10 as illustrated in FIG. 2a); in this case, the pilot has less time to implement the different landing procedures, which therefore become more risky.
• the pilot can decide to describe a loop 1 1 as illustrated in FIG. 2b); this allows him to capture the trajectory 1 at a point which will not penalize him for implementing the different landing procedures.
• this solution then delays the landing of the aircraft, which presents risks for the next aircraft when the landing windows between two aircraft are close together.
• An arc of a circle predicting the trend of the air path of the airplane as soon as it is turning, can also be calculated by the on-board calculation means and displayed on the navigation screen.
• An air path is an ideal path that does not take into account the effect of the wind. However, this is only a trend and such an arc of a circle does not predict the future air trajectory or the future ground trajectory of the aircraft before the turn, in particular in the event of wind.
• An important object of the invention is therefore to allow the best capture of a predetermined trajectory, taking into account the effect of the wind on the trajectory of the aircraft.
• the probe indicates the ground trajectory that the aircraft would follow if it immediately started a turn at the maximum rate applicable to the flight phase in which the aircraft is located.
• the invention proposes a method for assisting the navigation of an aircraft, characterized in that it comprises the following steps consisting in: a) calculating a probe as a function of the wind, b) display on a navigation screen the probe and a ground trajectory to be captured, in order to determine a turning of the aircraft making it possible to best capture the trajectory to be captured.
• it further comprises a step consisting in giving the order to turn when the probe tangents the ground trajectory to be captured.
• the method according to the invention is based on the simultaneous display (step b) of a trajectory to be captured which a priori does not change or little during capture and of a calculated probe (step a) according to the wind at successive instants: as soon as it appears that the probe is tangent to the trajectory to be captured, an order to turn the aircraft is given (step c), this turn making it possible, taking into account the wind, to capture the trajectory as well as possible, otherwise steps a), b) and c) are repeated.
• the turn is determined to allow better capture of the trajectory than if the aircraft had been turned while faithfully respecting the trajectory to be captured; blown away by the wind, the aircraft would then have captured the trajectory further (or possibly closer).
• This early (or even delayed) turn also makes it possible to accurately predict the capture point, that is to say the position relative to the ground of the capture point and possibly the instant of capture, regardless of the initial position and orientation of the aircraft and whatever the flight mode.
• the invention also relates to on-board equipment for assisting the navigation of an aircraft comprising at least one program memory and a user interface, characterized in that the program memory comprises a program for calculating a probe, and a program for displaying on the user interface a trajectory to be captured and the probe.
• FIG. 1 already described schematically represents a navigation screen on which is displayed a trajectory to be captured
• FIG. 3 is a flowchart representing the main steps of the method according to the invention
• FIG. 4 schematically illustrates the comparison of a probe and of a trajectory to be captured for two positions A or B of the airplane
• FIG. 1 already described schematically represents a navigation screen on which is displayed a trajectory to be captured
• FIG. 3 is a flowchart representing the main steps of the method according to the invention
• FIG. 4 schematically illustrates the comparison of a probe and of a trajectory to be captured for two positions A or B of the airplane
• FIG. 1 already described schematically represents a navigation screen on which is displayed a
• FIG. 5 represents schematically examples of probe shapes in the case of an instantaneous turn without drift of the aircraft, depending on whether the wind is a tail wind (a), a SE-NO wind (b) or a cross wind (c),
• FIG. 6 schematically represents an example of shape of right (D) and left (G) feeler including the turning distance and the aircraft drift for a SW-NE wind
• FIG. 7 schematically an on-board navigation aid device according to the invention.
• the method according to the invention is based on the simultaneous display (step b) of a trajectory to be captured which a priori does not change or changes little during the capture and of a calculated probe (step a) as a function of the wind at successive instants: as soon as it appears that the probe is tangent to the trajectory to be captured, an order to turn the aircraft (step c) is given, this turn allowing account given the wind to best capture the trajectory. Otherwise, steps a), b) and c) are repeated.
• FIG. 4 The comparison between the probe and the trajectory to be captured is illustrated in FIG. 4 on which the airplane 3 is represented at two places A and B of its trajectory.
• the probe 6A corresponding to position A of the airplane 3 does not yet tangent the trajectory 1 to be captured and steps a), b) and c) are repeated at the next instant.
• the probe 6B corresponding to the position B of the airplane 3 tangents the trajectory 1 to be captured; in this case the airplane 3 is turned at point B for a turn at the maximum rate, that is to say at the rate corresponding to that of the probe.
• This rate of turn is typically that which corresponds to a roll tilt of 25 °; it decreases at high altitude.
• This anticipation in B of the turn makes it possible to capture the trajectory 1 at point B 'and therefore earlier than if the airplane had been turned at point C, faithfully respecting trajectory 1; offset by the wind, the airplane 3 would then have captured the trajectory 1 only at point C after having followed the trajectory 10.
• This anticipation also makes it possible to precisely predict the point B 'of capture, that is to say say the position relative to the ground of the capture point and the instant of capture and this whatever the angle of interception, that is to say whatever the initial position and orientation of the airplane and whatever the piloting mode (with or without radar guidance, ).
• the steps a), b) and c) of calculation, display and conditional turn can be carried out automatically, that is to say by the calculation means on board the aircraft.
• the pilot visually compares by means of the navigation screen, the trajectory to be captured and the probe. As soon as it appears that the probe is tangent to the trajectory to be captured, the pilot gives the order to turn the airplane. Steps a), b) and c) can be carried out during the entire flight.
• FMS flight management system
• pilot flight management system
• a probe is obtained.
• right and a left probe or on the side of the desired turn and a right or left probe is obtained.
• each step of calculation, and / or display and / or conditional turn can be controlled by the pilot or automatically by the flight management system.
• the command in step a) and possibly in steps b) and c) can be selected by the pilot by means of, for example, a menu presented via a user interface such as the “MCDU” interface, acronym for "Muiti Control Display Unit", this interface being connected to the flight management system and the navigation receivers.
• This menu can allow the pilot to select the side of the desired turn for the probe, the probe only being displayed on this side.
• Steps a), b) and optionally step c) can also be controlled by the pilot or automatically on the occasion of a change of flight mode when, for example, switching from "HSV” mode, acronym of "Heading Vertical Speed” in which we undergo the wind, in FPA mode, acronym for "Flight Path Angle” in which we are freed from the wind.
• Steps a), b) and optionally step c) can also be controlled by the pilot by other means such as the rotation for example of a degree by the pilot of a selection button, on the side of the turn desired, the probe only being displayed on this side.
• Steps a), b) and c) can be interrupted as indicated above, on command of the flight management system or of the pilot, for example by turning the selection knob in the opposite direction.
• the probe is calculated according to the wind. We will first consider that the distance traveled by the aircraft to reach the inclination of the turn (25 ° for example) is zero; this distance is also designated by turning distance.
• the shape of the probe results from the rotation of the airplane around its center of turn composed with a translation of this center by effect of the wind.
• the turning distance is zero, it is obtained by a parametric equation which is expressed as follows in a reference frame (O, x, y) centered on the center of gravity of the aircraft, the Oy axis coinciding with the axis of the aircraft:
• R a ⁇ r being the radius of the turn that the airplane would have without wind
• ⁇ the angular speed (or rate of turn) of the airplane in the air during the turn that would have the airplane without wind
• V x and V y the components of the wind speed vector
• the sign in front of R a ⁇ r is the + sign when it is a probe to the right of the plane (right probe) and the sign - when it is a probe to the left of the plane (left probe).
• the shape of the probe and therefore the capture of the trajectory to be captured are optimal when the wind is constant and when the acceleration of the aircraft does not change between the start and the end of the turn.
• the parametric equation (1) does not take into account the turning distance, that is to say the trajectory segment corresponding to the turning time also designated by rolling time and which is related to the plane's inertia time; a good approximation consists in considering that this segment is straight and in the axis of the trajectory of the airplane. This amounts to adding for the calculation of y a term D v of turning distance.
• D v is expressed as follows:
• TAS being the linear ground speed of the airplane, in knots
• ⁇ rou the difference expressed in degrees between the roll angle at the end of the roll time, i.e. the roll angle that will have the plane at the start of the turn (25 ° for example), and the roll angle at the start of the roll (0 ° when the plane is not already in a turn)
• Equation (1) the roll rate in degrees per second, which depends on the airplane, and In a inertia factor in seconds, which depends on the airplane. Equation (1) becomes:
• the airplane when the airplane is subjected to the effect of the wind, it undergoes a drift; it follows that the axis of the trajectory generally no longer coincides with the axis of the aircraft as illustrated in FIG. 6.
• the drift angle d is the angle between these two axes.
• the shape of the right and left probes presented in Figure 6 by curves D) and G) was obtained from the following data.
• the aircraft flies at heading 275 ° (as shown in Figure 1), coinciding with the Oy axis with an air speed of 228 knots; its air turning radius is therefore equal to 1.62 Nm and its angular speed equal to 228 / 1.62 radians / hour.
• the Ox axis coincides with the 5 ° orientation.
• the navigation receivers indicate a wind of 35 knots from heading 170 ° (15 ° with respect to Ox), a ground course followed at 283 ° and a ground speed of 242 knots.
• the components V x and V y of the wind are respectively 34 and 9 knots.
• the turning distance D v at an inclination of 25 ° is calculated from the following data:
• Dv is the same for the right or left probes.
• the original roll angle is greater than about 2 °, the turning distance is shorter to the right than to the left; conversely, when the original roll angle is less than about -2 °, the turning distance is shorter on the left than on the right.
• trajectory we took as an example of a trajectory to capture a trajectory presenting a curve; the invention also applies to rectilinear trajectories or to other forms of trajectory.
• trajectories we can cite as examples of trajectories to be captured, an approach trajectory, an obstacle avoidance trajectory displayed on the navigation screen (relief, cloud masses provided by the weather radar, ...) or possibly traffic .
• the described method is implemented in on-board navigation aid equipment of an aircraft.
• this equipment 100 is shown in FIG. 7. It conventionally comprises one or more microprocessors 101 coupled to a program memory 102 of ROM type for example, to a working memory 103 of RAM type for example and to one or more memories 104 of ROM type for example for the storage of the trajectory to be captured and of the probe, as well as circuits 105 for transferring data between these various elements.
• the program memory 102 contains the executable program of the method, in the form of source code, while the working memory 103 includes registers which can be updated for storage of calculation results.
• This equipment 100 also includes a communication interface 106 to allow the exchange of data with devices such as for example with the user interface "MCDU", with sensors, etc. These elements are for example included in the flight management system, "FMS". They can also be included in the form of dedicated integrated circuits, designed to implement the method.
• the “MCDU” user interface comprises at least one navigation screen, means for displaying on this screen the trajectory to be captured and the probe and optionally means for controlling the calculation of the probe and / or the display of the probe. and / or turning the aircraft when the probe tangents the trajectory to be captured, via a keyboard for example.

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• Engineering & Computer Science (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Aviation & Aerospace Engineering (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Automation & Control Theory (AREA)
• Traffic Control Systems (AREA)
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• 2002
  • 2002-07-05 FR FR0208470A patent/FR2841977B1/fr not_active Expired - Fee Related
• 2003
  • 2003-06-27 EP EP03750784A patent/EP1520152A1/de not_active Withdrawn
  • 2003-06-27 WO PCT/FR2003/002001 patent/WO2004005853A1/fr not_active Ceased
  • 2003-06-27 US US10/519,470 patent/US7584027B2/en not_active Expired - Fee Related

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