Data processing: vehicles – navigation – and relative location – Navigation – Employing way point navigation
Reexamination Certificate
1999-02-24
2001-07-31
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Navigation
Employing way point navigation
C701S210000
Reexamination Certificate
active
06269301
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for piloting a vehicle following a trajectory comprising two non-aligned segments of route defining a change of heading, with compulsory overflying of the point common to the two segments.
2. Discussion of the Background
It applies in particular, but not exclusively, to the piloting of an aerodyne which follows a route which is generally defined by a set of transit points connected by rectilinear segments of trajectory, these transit points or “waypoints” indicating changes of heading.
These heading changes generally have to be made with a predetermined turning radius, for example one which varies as a function of the speed of the aerodyne in such a way as to maintain a constant angle of roll. To comply with a predetermined turning radius, it is therefore necessary to commence the turn either before the transit point, in which case the aerodyne will lie inside the planned turn, or at the moment at which the transit point is overflown, in which case the aerodyne will, after overflying the transit point, lie outside the planned turn and will then have to follow a trajectory intended to meet up with the initially planned route.
In the second case, it transpires, as represented in
FIG. 4
, that during its change of heading &Dgr;&psgr;, at the moment at which the transit point is overflown, the aerodyne strays significantly from the planned route R
1
, R
2
, and is even a relatively large distance d from it, which on the one hand causes a relatively large lengthening of the trajectory and on the other hand is undesirable in relation to surveillance and air control (compliance with variable lateral width margins).
SUMMARY OF THE INVENTION
The objective of the present invention is to eliminate these drawbacks. For this purpose, it proposes a method for piloting a vehicle with a view to making a change of heading, the vehicle following a first rectilinear portion of route, so as to meet up with a second rectilinear portion of route forming a predetermined angle with the first portion of route, by passing through the meeting point of the two portions of route.
According to the invention, this method is characterized in that it comprises the computation and following by the vehicle of a curved change of heading trajectory passing through the said meeting point, whose turning centre lies on the interior bisector of the angle formed by the two portions of route.
Such a change of heading trajectory offers numerous advantages by comparison with the trajectory of the prior art illustrated by FIG.
4
. This is because it makes it possible to save several seconds (up to 35 seconds or 4.5 nautical miles for a 90-degree turn). It deviates less from the planned route defined by the rectilinear sections of route (less than 30% of the deviation incurred by the conventional transition trajectory), this being of considerable benefit in respect of surveillance and air control. It also carries less risk of culminating in a linked succession of turns which criss-cross if the segments of route are short.
Moreover, if this change of heading trajectory is compared with the conventional trajectory which consists of a tangent curve to the two portions of route, which is situated inside the turn, it is observed that the trajectory according to the invention deviates less from the portions of route than the conventional trajectory.
Advantageously, the method according to the invention comprises the computation and following of two portions of curved linking trajectory, respectively between the first portion of route and the change of heading trajectory, and between the latter and the second portion of route, these two portions of linking trajectory having the same turning radius as that of the change of heading trajectory, and being tangent to the latter and to the two portions of route respectively.
The invention also relates to a method for avoiding a stationary polygonal zone applying the change of heading method to each corner of the polygonal zone.
This is because, in certain cases, it proves to be necessary to bypass a zone which it is prohibited to enter. Such cases arise in particular when there is a prohibition to overfly a zone of air space, such as a military zone or a state.
The avoidance method is aimed at determining the new route to be followed, by reducing as far as possible the distance to be travelled. For this purpose, it comprises the following steps:
the modelling of the contour of the zone to be avoided by a convex polygonal shape, by approximating the contour of the zone by a succession of segments, and eliminating the points of concavity and the excessively short segments,
the locating of the planned route with respect to the modelled zone,
the computation of port and starboard sections of route for exit and for return to the planned route, forming a predetermined angle with the latter and meeting up with the corner point of the polygonal shape which is closest to the planned route, so as to obtain two avoidance routes, port and starboard, formed by the exit and return sections of route and by the portions of the modelled contour respectively connecting the port and starboard exit and return transition sections of route, and
the selection of one of the two avoidance routes, port or starboard.
By virtue of these provisions, the trajectory followed passes as closely as possible to the boundaries of the zone without ever entering it.
REFERENCES:
patent: 4812990 (1989-03-01), Adams et al.
patent: 5058024 (1991-10-01), Inselberg
patent: 5445021 (1995-08-01), Cattoen et al.
patent: 5706011 (1998-01-01), Huss et al.
patent: 5774818 (1998-06-01), Pages
patent: 5850617 (1998-12-01), Libby
Cuchlinski Jr. William A.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Pipala Edward
Sextant Avionique
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