METHOD OF ASSISTING PILOTING AT LOW ALTITUDE

• US 20100332123A1
• Filed: 06/23/2010
• Published: 12/30/2010
• Est. Priority Date: 06/26/2009
• Status: Active Grant

• Current Assignee: Airbus Helicopters
• Original Assignee: Eurocopter
• Inventors: Gillet, Marianne, Filias, Francois-Xavier
• Granted Patent: US 8,364,330 B2
• Time in Patent Office: Days
• US Class Current: 701/206
• CPC Class Codes: G01C 23/00 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
• CPC Class Codes: G05D 1/0646 to follow the profile of undulating ground
• CPC Class Codes: G08G 5/0021 located in the aircraft
• CPC Class Codes: G08G 5/0086 for monitoring terrain radar or analogous systems specially adapted for terrain avoidance G01S13/935

Abstract

A method of assisting the piloting of an aircraft (60) at low altitude over terrain (S), in which method, during a first stage, a framework (10) is constructed from at least one main segment (40) and during a second stage a setpoint flight path (50) is constructed. More precisely, during the first stage, said main segment (40) is subdivided automatically into a plurality of secondary segments (41, 42, 43), each of said secondary segments (41) being situated at the same setpoint height above the highest point of the underlying terrain, with two adjacent secondary segments (41) being in alignment or connected together by a bar (44) that extends vertically in a vertical section.

Claims

1. A method of assisting the piloting of an aircraft at low altitude over terrain, in which method, during a first stage, a framework is constructed from at least one main segment of given corridor width that extends in a horizontal projection over a model of said terrain between successive first and second waypoints determined by an operator, and then during a second stage, a setpoint flight path is constructed with the help of said framework, wherein during the first stage, said main segment is automatically subdivided into a plurality of secondary segments of given corridor width so that the framework follows said terrain as closely as possible, said secondary segments going from a first secondary segment starting from said first waypoint to a last secondary segment terminating at the second waypoint, each secondary segment being arranged at a setpoint height above the highest point of the terrain that it overlies, said setpoint height is identical for all of the secondary segments of a main segment, with any two adjacent secondary segments that are not in alignment being connected together by a vertical bar in a vertical section of said terrain and containing said main segment.

2. A method according to claim 1, wherein for a setpoint secondary length to be reached by the secondary segments that has been determined, and for Euclidean division of a main length of the main segment by the setpoint secondary length giving a quotient and a remainder:

if said remainder is zero, then during the first stage, the main segment is subdivided into a number of secondary segments all having a real secondary length equal to said setpoint secondary length, the number of secondary segments being equal to the quotient; and

if said remainder is not equal to zero, then during the first stage, the main segment is subdivided firstly into a number of secondary segments all having the setpoint secondary length, that number being equal to said quotient minus one, and secondly into a lengthened secondary segment having a lengthened secondary length equal to the sum of the setpoint secondary length plus the remainder, said lengthened secondary segment being the first secondary segment of the main segment.

3. A method according to claim 2, said setpoint secondary length being determined by an operator.

4. A method according to claim 2, wherein, for an operator defining both a setpoint duration for traveling along a secondary segment and a setpoint indicated air speed, said setpoint secondary length is determined by multiplying said setpoint duration by a ground speed as calculated from said setpoint indicated air speed and the existing wind.

5. A method according to claim 1, wherein, during the first stage, for an operator specifying a given number of secondary segments of secondary length that is to be minimized, the altitude of each secondary segment is determined relative to a given reference level, and:

the secondary length of said given number of secondary segments is minimized to a given minimum length starting from the secondary segment having the greatest altitude and continuing in order of decreasing altitude in order to obtain said given number of minimized secondary segments;

each minimized secondary segment of altitude greater than the secondary segments adjacent thereto is centered so as to obtain a minimized secondary segment that is centered about the highest point of the terrain underlying said centered and minimized secondary segment; and

for said main segment including a first portion going from the first secondary segment to a centered and minimized secondary segment, for a second portion going from a centered and minimized secondary segment to the last secondary segment, and eventually for at least one intermediate portion between two centered and minimized secondary segments, the following steps are performed in each of said portions;

starting from each centered and minimized secondary segment, the adjacent secondary segments are moved longitudinally to reconstitute the framework; and

then

on reaching the secondary segments of said portion that has the lowest altitude, the lowest-altitude secondary segment is modified by lengthening or shortening its secondary length so as to obtain a modified secondary segment suitable for being connected to at least one adjacent secondary segment by a vertical bar.

6. A method according to claim 5, the secondary length of said first and last secondary segments never being minimized.

7. A method according to claim 6, wherein during an intermediate stage between the first stage and the second stage, the framework is optimized by minimizing the value of the following expression (E):

8. A method according to claim 7, wherein, for said framework being moved longitudinally through a given stepsize and in iterative manner over a given distance, with said value being recalculated on each step, the value of said expression is minimized during the second stage by using the framework that gave rise to a minimum value for said expression.

9. A method according to claim 5, wherein, if a movement, a shortening, or a lengthening of a secondary segment gives rise to a reduction or an increase in the height between the secondary segment and the terrain, then said secondary segment is moved vertically to said setpoint height above the highest point of the terrain that it overlies.

10. A method according to claim 5, wherein, for each secondary segment being required to have a secondary length lying between a given minimum secondary length and a given maximum secondary length, then:

if the secondary length of a secondary segment becomes greater than or equal to said given maximum secondary length, then said secondary segment in question is subdivided into two secondary segments of identical size; and

if the secondary length of a secondary segment becomes shorter than or equal to said minimum secondary length, then said secondary segment in question is eliminated and the adjacent secondary segment having the lower altitude is lengthened to compensate.

11. A method according to claim 1, wherein, for a setpoint secondary length to be reached by the secondary segments that have been determined, said main segment is subdivided into a plurality of secondary segments if the length of said main segment is greater than twice said setpoint secondary length.

12. A method according to claim 1, wherein, if during the second stage the constructed setpoint flight path does not make it possible to pass level over at least one secondary segment and gives rise to a continuously rising curve, then the framework is modified by fusing said at least one secondary segment with the secondary segment preceding said at least one secondary segment in order to construct a fused secondary segment which is given the altitude of said preceding secondary segment.

13. A method according to claim 1, wherein, if during the second stage the constructed setpoint flight path does not make it possible to pass level over at least one secondary segment and gives rise to a continuously descending curve, then the framework is modified by fusing said at least one secondary segment with the secondary segment following said at least one secondary segment in order to construct a fused secondary segment which is given the altitude of said following secondary segment.

14. A method according to claim 12, said fused secondary segment being constructed if said at least one secondary segment generating a continuously rising curve does not include said first secondary segment or if said at least one secondary segment generating a continuously descending curve does not include said last secondary segment.

15. A method according to claim 1, wherein, for display means presenting said main segment and presenting said aircraft extended by a rectilinear segment, if the aircraft is no longer following a main segment, when the rectilinear segment crosses a main segment once more, and on instruction from an operator, a return main segment is created that is subdivided automatically into a plurality of return secondary segments so that a return framework follows said terrain as closely as possible and gives rise to a return flight path.