FR2482342A1 - Artificial horizon device for flight simulator - projects film slide image onto wall of large diameter sphere containing flight cabin - Google Patents

Abstract

The artificial horizon device uses a lamp mounted at the centre of a transparent dome supported to allow rotation about an initial axis and a film slide carried by a support which rotates in synchronism with the dome about the same axis. The film slide is illuminated by a second lamp mounted on this axis cooperating with a fisheye lens used to project the film slide onto the surface of a sphere containing a cabin for the pilot. Pref. the film slide is attached to a rotatable disc incorporating a number of such slides with a separate drive motor for rotating it about an axis at an angle to the initial axis. The drive motors for controlling the various rotations may be controlled by a processor.

Description

The present invention relates to a horizon projection apparatus in an air flight simulation system and, more particularly, in an air combat simulation system.

 An air combat simulation system comprises two pilot cabins located respectively in two large diameter spheres.

In each sphere, the cabin being stationary, the horizon materialized by the dividing line between a well-lit surface representing the sky and a darker surface representing the earth, and, depending on the steering, the projection device delimiting the line separation simulating the horizon must be moved. In practice, the movements of movement of the projection apparatus are carried out along four axes of rotation making it possible to simulate all the yaw, roll and pitch movements controlled by the pilot. Systems with four axes of rotation are known and have was particularly developed by NASA at the Langley research center in the United States. In addition, given that, in the sphere, the pilot's eye and the projection device cannot be at the hanger thereof, this would result in precautions of parallax errors without precautions. In known systems, to avoid these errors, the axial position of the lamp used to project the image of the earth and the sky was modified. It should also be remembered that air combat simulation systems, as indeed flight simulation in general, use; to translate the pilot's actions into movements of the horizon projection device and the enemy aircraft projection device9 very powerful digital computers. The memories of these computers contain the aerodynamic equations of the simulated airplane and therefore deduce from the pilot's actions on the controls, the coordinates and the attitude angles of the airplane. Knowing the altitude of the plane and the attitude angles, the computers deduce the movements that must be given to the horizon projection device.

 In known horizon projection devices, we have so far confined ourselves to representing the earth by a very simple drawing darker than the sky which is white or light blue. However, experience has shown that pilots would like to have a more realistic picture of the earth's surface.

An object of the present invention is to provide a horizon projection apparatus also making it possible to project a real image of the ground.

 According to a characteristic of the invention, there is provided a horizon projection apparatus for an air flight simulation system suspended by - a system with three or four axes of rotation, comprising, on the one hand, a dome support. clear transparent that can rotate around an axis, with a first fixed lamp mounted in the center of the dome, and, on the other hand, a slide mounted on a support, rotating in synchronism with said dome around the same axis, the slide being lit by a second fixed lamp mounted on said axis and transmitting light to the entrance of a wide aperture objective of the "Fisheye" type mounted as a diverging lens to project the image of the device on the wall of a sphere.

 Next one. Another feature is a horizon projection device, in which the slide is fixed and transmits the light coming from said lamp to a Wollaston prism which can rotate around a first axis, the device comprising a bent tube at right angle, one end of which can rotate coaxially around said first axis and the second end of which supports a sleeve capable of rotating coaxially around a second axis normal to the first, a mirror clamp mounted at 45 at the top of the angle of said tube and returning the light received from the Wollaston prism towards a second mirror at 450 secured to said sleeve, which comprises a "Fisheye" objective mounted as a diverging lens on a third axis normal to the second and receiving the light from said second mirror, said sleeve still comprising a support for transparent d8me which can rotate around said third axis, the rotation of the first end of said tube causing rolling movement, the rotation of said sleeve has around the second end of said tube causing the pitching movement and the rotation of said Wollaston prism causing yaw movement, the rotations of said prism and said dome support being synchronous.

The characteristics of the present invention mentioned above, as well as others, will appear more clearly on reading the following description of exemplary embodiments, said description being made in relation to the accompanying drawings, among which:
Fig. 1 is the block diagram of a two-cabin air combat simulator,
Fig. 2 is a schematic view of a system with four axes of rotation,
Fig. 3 is a view in longitudinal section of the horizon projection apparatus, according to the invention, along a plane normal to the plane containing the axes of the journals supporting the apparatus,
Fig. 4 is a view in longitudinal section of the apparatus of FIG. 3, along a plane containing the axes of the pins supporting the device,
Fig. 5 is a cross-sectional view of the apparatus, along the line VV of FIG. 3,
Fig. 6 is a cross-sectional view of the apparatus, along the line VI-VI of FIG. 3,
Fig. 7 is a cross-sectional view of the apparatus, along the line VII-VII of FIG. 4,
Fig. 8 is a schematic view of the optical system of the device, and
Fig. 9 is. a longitudinal section view of a variant of the horizon projection apparatus of Figs. 3 to 7.

 In Fig. 1 two spheres 1 and 2 are shown, each containing a cabin 3 or 4. In the center of the sphere 1, in H1 is placed a horizon projection apparatus which generates the horizon line 5 between the light part symbolizing the sky and the dark part symbolizing the earth. The place of the eye of the pilot of cabin 3 is assumed at 01 and, above H1, slightly behind S point P1 indicates the location of the projection device of the silhouette C1 of the corresponding enemy aircraft to cabin 4. In sphere 2, we find the reciprocal points H2 for the horizon projection apparatus, 02 for the eye of the pilot of cabin 4, P2 for the silhouette projection apparatus C2 of the airplane in cabin 3. Between the two spheres a computer 6 has been symbolically represented which controls the movements of the aircraft nî> H1, H2, P1 and P2 according to the actions of the pilots on the controls of the cabins 3 and 4.

 In Fig. 1, it clearly appears that the point 01 or 02 not being in the center of the sphere like H1 or H2, there is a parallax error in the vision of the circle 5 by the pilot. In the embodiment described, we have chosen to place the device H1 in the center rather than the pilot's eye 01 to more easily allow the correction of this parallax error, as will be seen below.

In Fig. 2, there is shown, above the cabin 3, the assembly
ble of the 4-axis system 7, of which the projection apparatus is a part
horizon according to the invention. System 7 includes a room for 8
vant turn around a horizontal axis 9 carried by the fixed frame 10.

A fork 11 is mounted on an axis 12 carried by the part 8. Between the
fork fingers 11, using two aligned pins 13, is
mounted the projection device, inside which the
projection of light revolve around axis 14. Note that the
three axes 14, 13 and 12 are orthogonal, as in a 3-point system
axes, the fourth axis 9 of the system being added only to avoid
the well known borderline case. Remember that the 4-axis system has
the subject of developments by NASA in the United States and that it is
therefore no need to give a description here.

The sectional views of Figs 3 and 4 show the projecting apparatus
tion carried by the pins 13. It includes a fixed part comprising
as a cylindrical ring 15 of axis 14, to which are fixed, diam
trally opposite, the pins 13, FIG. 4, a transverse crown
16 supporting a cylinder 17, which carries at its upper end
a collar 18. On the collar 18, a circu flange is fixed
area 19 which is extended upwards by a truncated cone 20,
itself extended, upwards, by a short cylinder 21. Inside the lower part of the cylinder 17, is fixed another cylinder 22
provided, in its upper portion, with a rim 23 inwards. The
cylinder 22 is surmounted by a truncated cone 24 whose cross section
naked up.

Around the cylindrical part 21 is mounted a wheel bearing
ball bearing 25 which supports the cylindrical part 26 in one piece
mobile 27, which extends downwards through a conical part 28, then
a toothed crown 29, and, upwards, by a crown 30 provided
a rim 31.

Around the bottom of the cylindrical part 17 is mounted a bearing
with ball bearing 32 which supports a cylindrical part 33. The part
33 supports, at its periphery, a rotating collector with rings 34 and,
forward piece 35.

Finally, regarding the basic structure of the device
projection, the ring 15 carries a cylindrical casing 36, which is
also attached to the upper face of the flange 19 and to the face
lower part of the ferrule 37, the ferrule 37 being connected to the ring 15 by three tabs arranged at 1200.

 The crown 29 of the moving part 27 is rotated by a pinion, 38 applied to its periphery and driven by the axis 3S of output from a reduction gear 40, schematically represented in FIG. 6, itself driven by a motor 41. The axis 39 is obviously parallel to the axis 14 of the device. Far elsewhere by its periphery, the crown 39 drives another pinion 42, FIG. -3, which rotates an axis 43 which passes successively through the flange 19 and the crown 16 and which carries, at its other end, a pinion 44. The pinion 44 rotates the cylindrical part 33.

From the above description, it appears that the motor 41 drives the pinion 38, by 40 and 39, which rotates the part 27, which itself drives the pinion 42, therefore the pinion 44, by 43, which rotates the part 33. As a result, the parts 27 and 33 rotate in synchronism around the axis 14.

 The optical system of the device is in two parts, one above the crown 31 and the other below the part 19-20-21.

At the center of the fixed cylindrical part 21, a lamp 45 is mounted.

On the rim 31 of the rotating crown 30 is fixed a transparent dome 469 which can be colored blue with whitish traces to simulate, by projection, the sky. The d8me 46 has a hemispherical shape, the center 47 of which coincides with the location of the filament of the lamp 45, extended downwards by a cylindrical part covering the flange 31.

 The optical part intended to project a simulation of the ground comprises a lamp 489 FIG. 6s simply symbolized by point 48 on the Fridge 3 so as not to charge this last figure, a spherical mirror 49, applied to the bottom of the concave bowl formed by the conical part 20, a capacitor 50S blocked between the rim 23 of the cylinder 22 and the base of the conical part 24> and a lens 51 of the "FISHEYE" type having an opening of the order of 2200, which is mounted in the ferrule 37. On the optical plane, the lamp 48, the center of the filament of which is located on the axis 149 illuminates the mirror 49 which returns the luminosity towards the fisheye lens 51, through the capacitor 50.

This optical assembly obviously accepts axis 14 as its optical axis.

 On the optical path, just in front of the lens 51, is placed a slide 52, transverse with respect to 14. This slide was obtained by photographing the ground by means of a graphic camera provided with a “FISHEYE” type lens. Thus, the projection of this slide 52, using 51, on the wall of the sphere 1 (or 2) makes it possible to obtain an image which simulates the ground well.

 In fact, in the example of embodiment described, the slide 52 is part of a set of six slides which are mounted on a slightly conical disc 53, where they are angularly regularly spaced. In Fig. 3, the section shows two slides 52 arranged in corresponding holes in the disc 53. In its center, the disc 53 is carried by an axis 54 of a motor 55, which itself is mounted on the part 35. In the assembly described, the part 35 has the shape of a cylindrical housing hung at the bottom of the rotating part 33, with an oblique bottom relative to the axis 14 so as to compensate for the taper of the disc 53 so that the slide 52 is perpendicular to the axis 14.The bottom of the part 35 crosses the optical path, without intercepting it, given the opening 56 which has been made there in front of the optical beam. When the part 33 rotates it drives the part 35 in rotation about the axis 14, therefore also the motor 55 and the disc 53 for which the center of rotation is the intersection of the axis 14 with the center of the slide 52 , which is at this moment in front of the light path. The six slides differ from each other in that they were obtained at different altitudes. It follows that, if the stepping motor 55 is controlled in an adequate manner, as a function of the calculated altitude of the cabin during its notional flight, the representation of the ground can be made more likely to The pilot. Of course, at altitude levels, where the switching from one slide to another must take place, the motor 55 must be fast enough so that the change is not noticeable.

Between the capacitor 50 and the slide 52, at the end of the fixed cylindrical part 17, is mounted transversely an infrared filter 57, visible in plan in FIG. 5. The fixing of the plate 57, forming the filter, at the end of 17 can be carried out by conventional means, such as the small tabs 58. The purpose of the filter 57 is to stop the infrared radiation emitted by the lamp and especially to prevent most of it from reaching slide 52, which of course is very sensitive to heat. The direct cooling of the slide is moreover ensured by a fan 59,
Fig. 3, mounted under the part 35, on the other side of 55 with respect to the axis 14. The fan 59 is oriented so as to direct the cooling air on the slide 52.

 Fig. 3 also shows a fan 60 mounted on the fixed cylindrical part 17 and opening radially inside the latter, opposite the lamp 48 which it is intended to cool. As shown in Fig. 6, the lamp ventilation system 48 may include another fan 61, mounted like 60 on 17> -but angularly offset by nearly 1800. The housing 36 of the device has openings for the suction of air fresh through fans 59 60 and 61, as well as openings for the discharge of hot air. These openings are arranged so as not to let in light.

As shown in Figs. 6 and 7, the lamp 48 is mounted on a base 62 which passes radially through the cylinder 17. The base 62 can be removed to change the lamp 48 and is adjustable radially and laterally in position.

Fig. 8 shows the optical system proper, stripped of the mechanical elements which support it. The object of this optical system is first of all the image of the filament of the lamp 48 on the slide 52, then the projection of the slide 52 on the internal surface of the sphere 1 or 2 via the lens 51. A by way of example, the lamp 48 is a halogen lamp with a power of 100 W; the mirror 49 is a spherical mirror; the condenser 50 is a Leitz aspherical lens; and lens 51 is a brand fisheye
Nikkor. For a sphere 1 or 2 with a diameter of about 6.40 m, the optical system occupies between the top of 49 and the top of the outer face of 51, about 25 cm.

Fig. 4 shows that the apparatus also comprises a cylindrical crown 63 around the lens 51 and a cylindrical crown 64 around the dome 46. The crowns 63 and 64 have the axis 14 as their axis.

They are opaque. The circular edge 65 of the crown 63 defines, by projection onto the sphere 1, the line of separation between the hemisphere illuminated by the lens 51 and the hemisphere not illuminated by 51. Similarly, the circular edge 66 of the crown 64 defines, on sphere 1, the line of separation between the half-sphere lit by the dome 46 and the half-sphere not lit by 46. In practice, the two lines of separation must merge into a single line which is the line horizon 5, the half-sphere located above 5 being illuminated by the dome 46 and the half-sphere located below 5 being clearly seen by the slide 52 through the fisheye 51.

 The crown 63 is supported, by means of lugs 67, by the lower ends of two rods 68 and 69, parallel to the axis 14 and situated in the same diametral plane on either side of the ring collector 34. The crown 64 is mounted, by means of lugs 70, on the upper ends of the rods 68 and 69. The rods 68 and 69 pass through ball bushings 71 respectively mounted in corresponding holes in the cylindrical ring 15 and the ferrule 37. On the rod 68, above the ring 15, is fixed a block 72 carrying, towards the axis 14, a rack teeth which meshes with the teeth of a toothed wheel 73. As shown in FIG. 7, the wheel 73 is mounted at the end of the axis c a motor 74.

 The mechanical assembly comprising parts 68 to 73 makes it possible to move the crowns integrally and parallel to the axis 14 as a function of the estimated altitude of the cockpit. In fact, the higher the altitude, the more the pilot's eye must see the horizon line at a significant angle relative to the horizontal.

 In fact, as shown by Fdig. 1, the pilot's eye is not in the center of the sphere 1. Furthermore, the center of the device is in the center of the sphere, but not the lamp 45 or the lens 51 which are 20 cm approx. As a result, the lines defined by 65 and 66 are not perfect circles. In practice, the crowns 63 and 64 are spaced from each other by an amount which allows the coincidence of the curves forward and on the sides of the cabin, admitting a less good definition of the line of horizon backwards.

The motor 74 is controlled by the computer as a function of the altitude and of the corrections of parallaxes due to the offset of the pilot's eye.

 From the above description, it appears that the motor 40, by rotating the dome 46 in synchronism with the slide 52, makes it possible to make the yaw movement well, while having a projection of the ground quite likely since being the restitution of real photography. The motor 55 by changing the slide 52 placed in front of the light beam makes it possible, in stages, to modify the definition of the ground as a function of the altitude. The motor 74 by moving the crowns 63 and 64 makes it possible to place the horizon line correctly as a function of the altitude. The current collector 34 serves to supply the current to the motor 55 and to the fan 59, which are mounted on moving parts.

 Fig. 9 shows a variant of the apparatus of FIGS. 2 to 8.

It comprises an opaque cylindrical tube 75 open at its lower end and surmounted by a housing 76 which contains a lamp 77, a mirror 78 and a condenser 79. Around the bottom of the tube 75, there is provided a concentric tube 80, with between them bearings 81, allowing the rotation of 80 relative to 75. The tube 80, open downwards, is extended by a set of transparent rods 82, arranged in a circle, which themselves support a tube 83, closed at its lower end by a plate 84. The tube 83 has, just above 84, a transverse opening 85. Around the opening 85, is mounted a part of revolution 86 whose axis 87 is normal to the axis 88 common to 75, 80 and 83. The connection between 86 and 83 leaves no day between these two parts. The internal surface of the part 86 is slightly conical, its section reducing as it moves away from 83.The external surface of the part 86 is cylindrical, at least towards its free end, and surrounded by a concentric cylindrical part 89, with between 86 and 89 ball bearings 90 allowing the rotation of 89 relative to 86. Around the piece 89, is mounted a current collector with rings 91. At the free end of the piece 89, is fixed a plate 92, perpendicular to the axis 87. The plate 92 constitutes a lateral face of a parallelepiped casing 93 which in particular comprises an upper plate 94 and a lower plate 95. The plate 94 has an opening 96 intended to receive the end of a hollow axle 97 .The axle 97 carries, by means of bearings 98 a hub 99 which supports a circular plate 100 provided with a flange 101 on which is mounted a sky d8me 102. At the top of the hollow part of the axle 97 , a lamp 103 is mounted. The dome 102, the lamp 103 and the components 99, 100 and 101 which are associated are similar to parts 45, 46S 25, 30 and 31 of the exemplary embodiment of FIGS. 3 and 4. The hub 99 is driven by a pinion and motor system, similar to 38, 40, 41,
Figs. 3 and 6, but which is not shown in FIG. 9. The plate 95 has an opening in which is mounted a lens 104, identical to the lens 51. The lens 104 and the dome 102 have a common axis 105 which intersects the axis 87 at right angles. The lens 104 and the dome 102 are respectively surrounded by crowns 106 and 107 which are similar to the crowns 63 and 64 of the first embodiment and play the same role. They are linked together and moved together by means, not shown, similar to those already described. In the casing 93, the supply wires of the various motors and of the lamp 103 are still mounted, these wires being connected to the ring collector 91. Means, not shown, are also provided for rotating the part 89 around 86 and the tube 80 around the tube 75.

Furthermore, the apparatus of FIG. 9 includes a mirror at 450 108, mounted in the tube 83, for returning the light beam emitted by the lamp 77 along the axis 88 in the direction of the axis 87, and, in the casing 93, a mirror at 450 109 to return the light received along the axis 87 in the direction of the axis 105 towards the lens 104. There is also provision in the cylinder 75 for a Wollaston prism or an equivalent type 110, which is supported by means 111 represented symbolically and making it possible to rotate it around the axis 88.

Finally, between the condenser 79 and the prism 110, there is mounted in the tube a slide 112, which is part of a set similar to the set of slides 52 and plays the same role. The prism 110 is rotated, by the means 111, so that the image of the slide 112 rotates in synchronism with the dome 102.

Regarding the relative positions of the apparatus of the
Fig. 9 and the simulated cockpit, the assembly is such that the axis 88 is parallel to the longitudinal axis of the cabin and that the axis 87 is perpendicular to the first.

We will now describe the operation of the apparatus of the
Fig. 9. The light emitted by the lamp 77, part of which is reflected by the mirror 78, is concentrated on the slide 112 by the condenser 79, then passes through the prism 110, then is successively reflected by the mirrors 108 and 109 for be projected onto the sphere 1 after passing through the fisheye 104. When the housing 93 is rotated, secured to the part 89, around the part 86, a pitching movement of the cockpit is simulated. When the tube 80 is rotated around the tube 75, it simulates a rolling movement of the cabin. When the prism 110 is rotated around the axis 88, the light beam at the output of 110 rotates around its axis 88, so that the image projected by the lens 104 simulates a yaw movement.

As the dome 102 rotates in synchronism with the beam coming from the prism 110 the image of the sky on the sphere follows the same yaw movement.

Crowns 106 and 107 are moved, as already described for 63 and 64, as a function of the altitude of the simulated aircraft. The selection of the slide 112 placed on the light path is made according to the altitude and / or the horizontal path of the aircraft.

 Thus, it appears that the apparatus of FIG. 9, which reproduces the movements around three axes, can also be used in place of the first exemplary embodiment as a device for projecting the horizon. In fact, one can, with a few precautions, be enough to move around the axis sheep. But above all the apparatus of FIG. 9 has, as an advantage compared to the first embodiment, the particularity of allowing more easy substitutions of the slides 112 because the tube 75 in which they are to be selectively inserted is a fixed part. Thus, the slides can be part of a film which passes step by step through the tube 75 and the number of slides can be greater. it also allows you to predict crossfades. In the first embodiment, since the dimensions of the device must be reduced so as not to increase its inertia too much, and in practice are of the order of 8 cm with regard to the radius of the housing 36, the disc 52 has a diameter of the order of 6 cm, which only accommodates six slides. But, and this is an even more striking advantage, the apparatus of FIG. 9 makes it possible to replace the slide and the light source 77, 78 and 79 with a high-gloss electronic tube, an electronic light valve, or the like. The use of a high-gloss tube obviously makes it possible to vary the landscape much more easily than with slides and continuously depending on the altitude and movement of the aircraft.

Claims (4)

 1) Horizon projection apparatus for an air flight simulation system suspended by a system with three or four axes of rotation, characterized in that it comprises, on the one hand, a clear transparent dome support which can rotate around an axis, with a first fixed lamp mounted in the center of the dome, and, on the other hand, a slide mounted on a support, rotating in synchronism with said dome around the same axis, the slide being lit by a second fixed lamp mounted on said axis and transmitting light at the entrance of a wide aperture objective of the "Fisheye" type mounted as a diverging lens to project the image of the slide on the wall of a sphere.  2) Apparatus for projecting the horizon, characterized in that the slide is fixed and transmits the light coming from said lamp to a prism of the Wollaston type which can rotate around a first axis, the apparatus comprising an angled tube at an angle straight, one end of which can rotate coaxially around said first axis and the second end of which supports, a sleeve capable of rotating coaxially around a second axis normal to the first, a first mirror mounted at 450 at the top of the angle of said tube and returning light received from the prism of Wollaston towards a second mirror at 450 secured to said sleeve, which comprises a "Fisheye" objective mounted as a diverging lens on a third axis normal to the second and receiving the light from said second mirror, said sleeve also comprising a transparent dome support which can rotate around said third axis, the rotation of the first end of said tube causing rolling movement, the rotation of said sleeve around the second end of said tube causing pitching movement and the rotation of said Wollaston prism causing yaw movement, the rotations of said prism and said dome support being synchronous.  3) projection apparatus according to claim 1 or 2, characterized in that, on the one hand, around said dôrne is provided a first coaxial opaque crown and, on the other hand, around a fisheye lens is provided a second crown opaque coaxial, the mutual distance from their most distant edges being determined so that the projections of these extreme edges coincide on the projection sphere and define the horizon, the two crowns being moved parallel to their mutual axis according to the altitude and the attitude of the plane.  4) apparatus for horizon projection according to claim 1, characterized in that it comprises a disc comprising a plurality of openings regularly distributed in a circle, each opening supporting a slide, the disc being able to rotate step by step around a axis attached to the camera so that you can change the light intercepting slide between the second lamp and the fisheye lens.