Head-mounted display system comprising heading selection means
and associated selection method
The field of the invention is that of viewing systems mounted on
the head of the crew members of an aircraft. More precisely, the invention
relates to the display and the selection of heading by this type of viewing
system.
Helmet or head viewing systems have commonly been used for
aeronautical applications for several decades. A head viewing system mainly
comprises two sub-assemblies.
The first sub-assembly is a helmet or a headset equipped with a
10 viewing system which projects a collimated image, superimposed on the
exterior, toward the user's eye or eyes. Helmet is intended to mean a
structure for protecting the head, said structure carrying a certain-number of
phone or viewing or detection devices. Headset is intended to mean a
structure carrying a certain number of phone or viewing or detection devices
15 and not necessarily ensuring a protection function for the head. The system
according to the invention is equally a helmet or a head support.
The second sub-assembly is a head posture detection system
making it possible to pinpoint in space, with respect to a known reference
frame, generally tied to an aircraft, the position and the orientation of the
20 helmet or of the headset. The main function of the viewing system is to be
able to present, superimposed on the exterior landscape, so-called
"conformal" information, that is to say displayed virtually in the exact direction
that it would occupy in the exterior landscape. Thus, if the system displays a
video image arising from a sensor and comprising a certain number of
25 objects, the objects represented of this image are exactly superimposed with
the objects present on the terrain. The same goes for synthetic
representations of objects such as runways, targets or direction indications.
Currently, when the crew wishes to follow a heading tied to an
30 element of the exterior scene, they must firstly determine the heading
associated with the exterior element and then input it into the avionics
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system, in general with the aid of a rotary knob mounted on a control post.
The object of the invention is to simplify this operation by using the inherent
resources of helmet or head viewing systems and in particular in displaying
conformal information.
More precisely, the subject of the invention is a head viewing
system for aircraft comprising a head support, a viewing device, a detection
of posture of said head support, means for detecting the current heading of
an aircraft and means for graphically generating said current heading,
characterized in that the system comprises means for controlling, displaying
10 and selecting headings, said means arranged so as:
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- to display, in the viewing device, in response to a first command, a
second so-called setpoint heading and a third heading termed a
"support heading" corresponding to the direction of the head
support in a terrestrial reference frame, said direction given by the
information arising from the detection of posture of said head
support and the means for detecting the current heading;
- to replace, in response to a second command, said second
heading by said third heading, said third heading thus becoming
the new heading setpoint.
Advantageously, when the headings lie in the viewing field of the
viewing device, the display of the value of the heading is carried out in
conformal position, that is to say in the exact direction which corresponds to
the direction of the heading.
Advantageously, when the headings lie outside the viewing field of
25 the viewing device, the display of the value of the heading is carried out at
the edge of the field of the viewing device with an icon representative of the
direction in which the heading lies.
Advantageously, the exact direction of the heading is indicated by
a vertical bar, each heading comprising a bar of a different graphic from that
30 of the other heading bars.
The invention also relates to a method of displaying, managing
and selecting the heading in a head viewing system for aircraft, said viewing
system comprising a head support, a viewing device, a detection of posture
of said head support, means for detecting the current heading of an aircraft
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and means for graphically generating said current heading, characterized in
that the method comprises at least:
- a step of displaying, in response to a first command, a second socalled
setpoint heading and a third heading termed a "support
heading" corresponding to the direction of the head support in a
terrestrial reference frame, said direction given by the information
arising from the detection of posture of said head support and the
means for detecting the current heading.
Advantageously, the method comprises:
10 - a step of substituting, in response to a second command, the
second heading by the third heading, said third heading thus
becoming the new heading setpoint.
The invention will be better understood and other advantages will
15 become apparent on reading the nonlimiting description which follows and by
virtue of the appended figures among which:
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Figures 1 to 4 represent the various possible displays of the
heading in a head viewing system for aircraft according to the invention.
The head viewing system according to the invention comprises:
- an equipped head support or a helmet comprising an
optoelectronic display assembly. This viewing assembly can be monocular or
binocular. When the head support or the helmet is worn by a user, this
assembly gives a collimated image which arises from a display unit and
25 which is superimposed on the exterior landscape by an optical combiner or
mixer;
- a system for detecting posture of the head support or of the
helmet making it possible to determine the position of the support or of the
helmet in the reference frame of the aircraft. Various detection systems exist
30 which are well known to the person skilled in the art. Mention will be made of
systems based on magnetic detection in which a receiver measures the
components of a known electromagnetic field and systems based on optical
detection comprising an emitter and a receiver which is able to determine the
position and the orientation of this emitter by shape recognition. The position
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of the aircraft in a terrestrial reference frame is itself known by means of
various sensors such as the aircraft's inertial platform;
- an assembly or an electronic computer ensuring the generation
of a conformal symbology superimposed on the exterior landscape by the
5 optoelectronic display assembly. This symbology generally comprises the
basic information necessary for piloting (indications of the speed, of the
altitude, of the attitude, of the horizon, etc.). To ensure this function, the
aircraft's various sensors provide the computer with the necessary
information. The helmet's orientation detection system gives it the position
10 and orientation information making it possible to display the symbology in a
conformal manner, that is to say in a terrestrial reference frame independent
of the movements of the aircraft and of the movements of the helmet;
- control means, generally one or more control posts making it
possible to select, modify or validate the information and the data displayed
15 by the viewing device. These control means can also be disposed on the
control stick or be activated by a voice command.
The computer also ensures the specific functions of the invention
that are linked to the display of the heading. They are represented in Figures
20 1 to 4 by way of nonlimiting examples. These figures represent in a
schematic manner the display of the heading in a helmet viewing device. In
these figures, the rectangular outline represents the limits of the field of the
viewing device. The landscape P is represented symbolically by ridge lines in
these figures. For the sake of clarity, all the symbology having nothing to do
25 with displaying the headings has been deleted from the figures.
In Figure 1, the system displays solely at the center and at the top
of the viewing field the current heading C1, that is to say the one actually
followed by the aircraft at an instant t. In this Figure 1, the displayed value of
30 the heading C1 is "266". All the displayed values are in degrees.
In Figure 2, the pilot has validated the heading display function
according to the invention. The system then displays the setpoint heading
C2. In this Figure 1, the displayed value of the heading C2 is "260". It also
35 displays a third heading C3 termed a "support heading" corresponding to the
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direction of the head support in a terrestrial reference frame. The value of the
heading C3 is given by the information arising from the detection of posture
of said head support and the means for detecting the current heading. The
displayed value of the heading C3 is "271". The system also displays a first
5 vertical bar Bc2 whose bearing cuts the exact direction of the setpoint
heading C2 and a second vertical bar Bc3 whose bearing cuts the exact
direction of the heading C3. This second bar is, by nature, disposed at the
center of the field of the viewing device and remains fixed. These bars are
therefore placed in conformal position. They have different graphical
10 representations so as to differentiate them. In the figures, the first bar is
represented by a continuous line and the second bar by a dashed line. Of
course, it is possible to involve other parameters such as the length, the
thickness or the color of the bars.
15 Figure 3 represents the evolution of the symbology of the
headings when the pilot turns his head to designate another direction. The
value of the setpoint heading C2 does not change. It remains at the value
"260". On the other hand, if this heading exits the visual field, its value
remains indicated in the field of the viewing device, but its representation bar
20 Bcz which was in conformal position disappears. It is replaced with an icon
which indicates that the setpoint heading has exited the visual field. In Figure
3, by way of example, this icon is a chevron whose tip is pointing in the
direction of the setpoint heading. The value of the heading C3 which depends
on the posture of the helmet changes. It goes to the value "302", the pilot
25 having turned his head, in this example, by 31 degrees. Of course, the
second vertical bar Bc3 remains fixed in the reference frame of the helmet
display.
The pilot can, at each instant, validate the direction of the support
30 heading which then becomes the new setpoint heading. Thus, in Figure 4,
the pilot has validated the support heading C3 of Figure 3 whose value was
"302". The new setpoint value C2 therefore now equals "302". At the time of
the validation, the two vertical bars Bc2 and Bc3, indicating the headings C2
and C3, are merged as seen in Figure 4.
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In the various figures, the value of the current heading C1 has
remained unchanged, indicating that the aircraft has not changed direction
while the pilot turned his head. When the user validates the new setpoint
heading, the heading associated with the direction of their head at the time of
5 the validation is the new heading taken into account by the aircraft's
navigation system. If the automatic pilot is engaged, the new heading is that
followed by the aircraft, if the automatic piloting is not engaged, the pilot
manually follows the new heading indicated in the viewing device.

CLAIMS
1. A head viewing system for aircraft comprising a head support, a
viewing device, a detection of posture of said head support, means for
detecting the current heading of an aircraft and means for graphically
generating said current heading (C1), characterized in that the system
5 comprises means for controlling, displaying and selecting headings, said
means arranged so as:
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- to display in the viewing device, in response to a first command, a
second so-called setpoint heading (C2) and a third heading (C3)
termed a "support heading" corresponding to the direction of the
head support in a terrestrial reference frame, said direction given
by the information arising from the detection of posture of said
head support and the means for detecting the current heading;
- to replace, in response to a second command, said second
heading by said third heading, said third heading thus becoming
the new heading setpoint.
2. The helmet viewing system as claimed in claim 1, characterized
in that, when the headings lie in the viewing field of the viewing device, the
display of the value of the heading is carried out in conformal position, that is
20 to say in the exact direction which corresponds to the direction of the
heading.
3. The helmet viewing system as claimed in claim 2, characterized
in that, when the headings lie outside the viewing field of the viewing device,
25 the display of the value of the heading is carried out at the edge of the field of
the viewing device with an icon representative of the direction in which the
heading lies.
4. The helmet viewing system as claimed in one of the preceding
30 claims, characterized in that the exact direction of the heading is indicated by
a vertical bar, each heading comprising a bar of a different graphic from that
of the other heading bars.
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5. A method of displaying, managing and selecting the heading in
a helmet viewing system for aircraft, said viewing system comprising a head
support, a viewing device, a detection of posture of said head support,
5 means for detecting the current heading (C 1) of an aircraft and means for
graphically generating said current heading, characterized in that the method
comprises at least:
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- a step of displaying, in response to a first command, a second socalled
setpoint heading (C2) and a third heading (C3) termed a
"support ·heading" corresponding to the direction of the head
support in a terrestrial reference frame, said direction given by the
information arising from the detection of posture of said head
support and the means for detecting the current heading.
6. The method of displaying, managing and selecting the heading
as claimed in claim 5, characterized in that the method comprises:
- a step of substituting, in response to a second command, the
second heading by the third heading, said third heading thus
becoming the new heading setpoint.