Classifications

• • 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
  • G05D1/04—Control of altitude or depth
  • G05D1/06—Rate of change of altitude or depth
  • G05D1/0607—Rate of change of altitude or depth specially adapted for aircraft
  • G05D1/0646—Rate of change of altitude or depth specially adapted for aircraft to follow the profile of undulating ground
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
  • G01C21/00—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00
  • G01C21/20—Instruments for performing navigational calculations

Definitions

• the invention relates to navigation at low altitude of an aircraft.
• Methods of assisting navigation at low altitude are already known for highly maneuverable aircraft such as fighter aircraft. But they are not suitable for aircraft with limited maneuverability performance such as cargo planes or airliners.
• An important object of the invention is therefore to propose a three-dimensional (3D) navigation aid method, secure, at low altitude for an aircraft having limited performance.
• a low-altitude flight profile is determined from the safety profile and the performance profile. This process makes it possible to quickly calculate a three-dimensional flight profile that is safe and optimized to follow the ground trajectory, in particular in an environment with significant relief; it thus makes it possible to minimize the time during which the pilot of the aircraft must pilot manually before the automatic pilot can regain control with security on the updated 3D profile.
• the flyable profile is thus always higher than the (or equal to) security profile and therefore does not require a posteriori verification of the altitudes of the profile compared to those of the terrain.
• the flight management computer having wind speed and direction, aircraft speed, terrain altitude, local temperature, the MaxClimbFPA and MaxDescFPA slopes are preferably weighted according to the wind speed and direction and / or aircraft speed, and / or terrain altitude and / or local temperature.
• the invention also relates to a flight management system comprising a central unit which communicates with an input / output interface, a program memory, a working memory, a data storage memory, by means of transfer circuits. data, the input-output interface being connected to a database of the terrain to be overflown, characterized in that the program memory comprises a program for implementing the method as described.
• FIG. 1 schematically represents an FMS flight management system
• Figures 2a and 2b schematically represent a safety profile, seen in a section perpendicular to the ground path (Figure 2a), or in perspective ( Figure 2b)
• Figure 3 illustrates the maximum climb slopes MaxClimbFPA and maximum descent MaxDescFPA
• FIG. 4 schematically represents a ground trajectory, and safety, performance and flyable profiles at low altitude seen in section along the axis of the ground trajectory
• FIGS. 5a, 5b, 5c, 5d schematically illustrate the calculation of a vertical transition around a summit or an obstacle S.
• the aircraft comprises a flight management computer FMS (acronym of the expression Anglo-Saxon "Flight Management System”).
• FMS computer represented in FIG. 1 conventionally comprises a central unit 101 which communicates with an input-output interface 106, a program memory 102, a working memory 103, a data storage memory 104, by means of circuits 105 for transferring data between these various elements.
• the input-output interface is connected to various devices such as a man-machine interface 107, sensors 108, etc.
• a performance table, specific to the aircraft, and a ground flight plan trajectory are stored in the data memory.
• a ground flight plan trajectory is established from a list of waypoints PP that the aircraft must fly over and is composed of straight and or curved segments joining these points as illustrated in FIG. 2b.
• the curves correspond to transitions calculated around the points PP taking into account the limitations of the aircraft.
• This ground trajectory is sampled according to a step p: a list of waypoints P, of ground altitude alt (P) is then obtained.
• the performance table we find the performance and limitations of the aircraft, for example the speed, slope of the aircraft, its maximum altitude, its stall speed, its consumption, its radius of turn, its roll, etc.
• the FMS computer is linked in particular to a database 109 of the terrain to be overflown, generally represented in the form of rectangular meshes.
• the method according to the invention is based on the determination of a low altitude flight profile by means of the FMS computer. It includes the following stages which consist in: a) Calculating from the ground trajectory, right lateral margins “mrg lat D" and left “mrg lat G” according in particular to the performance and limitations of navigation of the aircraft and the error on the estimated position or EPU (acronym of the Anglo-Saxon expression "Estimated Position Uncertainty").
• EPU anglo-Saxon expression "Estimated Position Uncertainty”
• the lateral margins are updated as well as the calculation which follows. These lateral margins are possibly identical.
• MaxClimbFPA is notably determined as a function of the available power of the aircraft and possibly assuming an engine failure.
• the altitude of a starting point S and the maximum weighted slopes define two performance segments which have a first end in S, weighted MaxClimbFPA and MaxDescFPA slopes on either side of point S and a second end at point d intersection with the relief or with another segment.
• the segments determined for all the points S form a performance profile, which makes it possible to associate with each point P of the ground trajectory, a performance altitude, "ait perf".
• a performance altitude As for a point on the ground trajectory, there are two performance altitudes from performance segments, one rising, the other descending, the highest altitude is used as illustrated in Figure 3, in region III.
• the determination of this flyable profile can be optimized according to the following three criteria which are minimized depending on the context: - average height between the flyable profile and the altitude of the terrain, - lateral margins, - response time of the calculation of the flyable profile by the flight computer.
• the last criterion is preferred.
• Other optimizations can intervene.
• a first solution consists in taking a larger sampling step p.
• Another solution consists in using a sampling step p varying as a function of the slope of the terrain; the points of the ground trajectory are filtered according to the slope between these points.
• the lower the slope the greater the step p and, conversely, the more the slope varies, as is the case in mountainous terrain, the smaller the step p.
• the step has a lower limit p ⁇ nf and an upper limit p su •
• p ⁇ f equal to half a mesh width of the terrain database, ie approximately 0.15 / 2 N (nautical miles) and p sup equal to about 1km.
• 5c consists in artificially raising the flyable profile at S by a height ⁇ H to obtain S ': the expected vertical transition TV is thus also raised by ⁇ H with respect to TV.
• the flyable profile is then modified by adjusting the segments SegClimb, SegDesc coming from S, so that the new segments SegClimb ', SegDesc' coming from S 'are tangent to the expected transition TV as illustrated in FIG. 5c: we then obtain a new flyable profile.

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• Engineering & Computer Science (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Automation & Control Theory (AREA)
• Aviation & Aerospace Engineering (AREA)
• Traffic Control Systems (AREA)
• Navigation (AREA)

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• 2003
  • 2003-12-19 FR FR0315035A patent/FR2864269B1/fr not_active Expired - Fee Related
• 2004
  • 2004-12-13 EP EP04804792A patent/EP1695164A1/de not_active Withdrawn
  • 2004-12-13 US US10/583,143 patent/US7584046B2/en not_active Expired - Fee Related
  • 2004-12-13 WO PCT/EP2004/053431 patent/WO2005069094A1/fr active Search and Examination
• 2006
  • 2006-05-25 IL IL175942A patent/IL175942A0/en unknown

Non-Patent Citations (1)

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