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Bodenseewerk Geräteechnik GmbH, 88662 Ueberlingen
The invention relates to a seeker head with a roll axis and a pitch-yaw inner gimbal system, comprising an inner gimbal frame, which is pivotably mounted on a bearing structure about a first gimbal axis, and an outer, carrying a finder system of the seeker head, Gimbal, which is pivotally mounted on the inner gimbal about a second, perpendicular to the first gimbal axis.
Such search heads are used in particular in target-tracking missiles. An optical system as a viewfinder system generates an image of an object scene containing the target on a detector. From the signals of the detector, signals are obtained which keep the optical axis of the optical system aligned with the target. In addition, steering signals are obtained from the signals of the detector, through which the missile is guided to the target. Usually, a platform carrying the optical system and thus the direction of the optical axis of the optical system is decoupled from the movements of the missile by an inertial measuring system. If a control loop keeps the optical axis aligned with the target, the optical axis corresponds to the line of sight from the missile to the target.
The rate of rotation of the line of sight in the inertial space can then be determined from the movement of the optical axis relative to the stabilized platform. With normal proportional navigation, the missile is guided so that this line of sight remains fixed in space. The steering signals are made proportional to the rate of rotation of the line of sight. The platform must be gimbaled so that the optical axis of the optical system can assume any position within a certain solid angle.
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The gimbal mounting can be a pitch-yaw mounting. Here, a first gimbal is about a first axis substantially transverse to the longitudinal axis of the missile, z. B. the pitch axis, pivoted relative to the missile structure. On the first gimbal is a second gimbal about a second axis, for. B. the yaw axis, pivotally mounted, which is perpendicular to the first axis. This second gimbal supports or forms the platform on which the optical system sits. The first gimbal mounted on the missile structure can be the outer gimbal, while the second gimbal forms the inner gimbal. One then speaks of an "outer gimbal system".
The first gimbal mounted on the missile structure can then also be the inner gimbal, the second gimbal carrying or forming the platform being the outer gimbal. In this case one speaks of an "inner gimbal system". The gimbal system then sits inside the platform. This latter arrangement is preferred for spatial reasons.
In such a pitch-yaw gimbal system, the swivel angle of the platform and thus the squint angle, which form the optical axis with the missile longitudinal axis, are limited for design reasons. The viewfinder can only capture a target in a limited field of view.
A seeker head with a pitch-yaw inner gimbal system is described, for example, in DE 195 35 886 A1 or EP 0 766 065 B1.
Larger squint angles can be achieved with a roll-nick cardan system.
Here, a first, shaft-like gimbal is mounted in the missile structure so that it can rotate about a roll axis coinciding with the missile longitudinal axis. This first gimbal can be rotated around the roll axis in an angular range of 360 with respect to the missile structure. A second gimbal is pivotally mounted on the first gimbal frame about a pitch axis running perpendicular to the roll axis. This second gimbal carries the optical system of the seeker head. The second gimbal can be mounted in such a way that the optical axis of the optical system can be pivoted through an angle of approximately 90 with respect to the longitudinal axis of the missile.
So squint angles up to 90 are possible, in each direction around the rolling
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axis around. A search head constructed in this way can thus be aimed at a target within a half space.
Search heads with roll-nick gimbal systems are known from DE 33 17 232 A1 and DE 198 24 899 Cl.
A disadvantage of such roll-nick gimbal systems is that they show a singularity in the area of the roll axis: If the line of sight to the target, which the optical axis of the optical system is supposed to track by rotating the gimbal frame, coincides with the roll axis or runs close to it , then even small movements of the optical axis require large angular movements of the roller blind. If z. If, for example, the line of sight to the target is moved through the roll axis, then the rolling frame would have to rotate by 180 practically in an infinitely short time in order to track the optical axis of this line of sight. This exceeds the possibilities of conventional servomotors.
The invention has for its object to provide a gimbal system for a seeker head, in which the tracking of the platform and the finder system takes place without singularities, but which allows large squint angles and the detection of targets in a large field of view.
According to the invention, this object is achieved in that the first cardan axis forms an acute angle with the roll axis and the bearing structure is in turn rotatably supported about the roll axis.
Because the first gimbal axis forms an acute angle with the roll axis, the gimbal system sits at an angle to the roll axis. The swiveling range of the outer gimbal with the viewfinder system is therefore asymmetrical to the roll axis. If you consider the central position of the inner frame, which can be pivoted about the first gimbal axis, the following results: If a denotes the acute angle and 2ss the pivoting range of the outer frame around the second gimbal axis, then the maximum achievable squint angle between the roll axis and the axis of the viewfinder system 90 -a + ss. A larger squint angle can therefore be achieved. If the target is in azimuth from that by the
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Pivoting range of the gimbal system moves certain solid angle, this can be compensated for by rotating the gimbal system about the roll axis.
The solid angle determined by the swivel range of the gimbal system is tracked to the target. In a further advantageous embodiment of the invention, the bearing structure, which is rotatably mounted about the roll axis, is additionally rotatably supported about its own longitudinal axis. The associated introduction of a further degree of rotational freedom means that rotational movements of the rolling frame can be compensated for by rotational movements of the bearing structure about its longitudinal axis with the opposite direction of rotation. Roll angles of over 360 ', which lead to excessive stress on electrical connecting lines and high-pressure couplings for gas feeds, no longer occur. The reliability or lifespan of the seeker head is thus increased.
In addition, with this configuration, the use of cost-intensive, high-pressure rotary couplings and slip rings for electrical taps can be dispensed with. The mass to be rotated can be reduced by decoupling the pitch-yaw gimbal system from rolling movements of the rolling frame by means of the bearing structure which can be rotated about its longitudinal axis. Lower motions are therefore required for movements around the roll axis and the construction volume of the roll frame can be reduced.
A fixation of the pitch-yaw gimbal system with regard to its roll position to the missile structure is expediently provided by means of fixation means. The fixing means can be toothed elements in the form of gearwheels, a gearwheel being integrated in the missile structure and a gearwheel between the pitch-yaw frame system and the new degree of freedom of rotation. In other words, the pitch-yaw frame system rolls when rotating about the roll axis with the opposite direction of rotation about the longitudinal axis of the bearing structure. Cleverly, the gears are molded parts made of plastic with a low weight. Plastic can be used because only small moments have to be transmitted.
It makes sense to have
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Gears the same number of teeth to achieve a gear ratio of one.
By rotating the roll axis and simultaneously untwisting it by rotating the bearing structure about its longitudinal axis, hereinafter also called the wobble axis, and fixing it by means of the fixing means, the pitch-yaw gimbal system is able to move around the longitudinal axis of the missile, ie. H. the roll axis to wobble at a fixed angle of (90 -a) without generating rotating components in the roll axis. The wobble angle is usually in the range of 15-30. There is no image rotation with respect to the missile coordinate system. The mechanical fixation eliminates the need for drive and tapping elements for producing a rotary movement of the bearing structure about its longitudinal axis, for example in the form of an electric motor and electrical connecting lines.
This saves a further mass and volume.
The solid angle at which the optical axis of the optical system can be deflected by pivoting movements about the first and the second car axis advantageously contains the roll axis.
In order to stabilize the optical system in space, an inertia measuring unit can be provided, by means of which servomotors can be controlled around the first and the second cardan axis, an actuating motor acting around the roll axis being provided which, when the inner gimbal frame is located approaches its stop position, can be controlled in the sense of tracking this inner gimbal away from the stop position.
The axis of the finder system can thus be directed to any point within a large solid angle extending around the roll axis. Stabilization is carried out using the pitch-yaw gimbal system. This pitch-yaw gimbal system also has no singularity in the area of the roll axis. When the line of sight passes through the roll axis, the pitch-yaw
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Cardan system only normal adjustment movements. A 180-turn-over is not necessary as with a roll-nick gimbal system.
Exemplary embodiments of the invention are shown in the drawing. The drawing, the description and the claims contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them into useful further combinations.
1 shows a longitudinal section through a seeker head with an inclined pitch-yaw gimbal system and an additional tracking movement about the roll axis.
FIG. 2 is a block diagram and illustrates the tracking of the
Finder system for a line of sight to a target.
Fig. 3 is a diagram illustrating the enlargement of the
Range of allowable squint angles of the seeker head of FIG. 1.
FIG. 4 shows a longitudinal section through a seeker head with an inclined pitch-yaw gimbal system and with a bearing structure rotatably mounted about a roll axis and its own longitudinal axis.
FIG. 5 shows a longitudinal section through a seeker head according to FIG. 4 with
Fixing means for the pitch-yaw gimbal system with respect to one
Roll position of the missile structure.
The same parts are designated with the same reference numerals.
1, 10 denotes the tip of the missile structure of a target-tracking missile. The tip 10 is closed off by a spherical window (dome) 12. Behind the dome 12 is a search head, which is designated 14.
The seeker head 14 contains a table 16 which is rotatable about a roll axis 18 coinciding with the longitudinal axis of the missile in the tip 10 of the missile.
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body structure is stored. A sleeve-shaped bearing body 20 sits on the table. The bearing body 20, also called the bearing structure, is arranged inclined to the roll axis 18. At the front or dome-side end of the bearing body 20, an inner frame 22 is pivotally mounted about a first gimbal axis 24 perpendicular to the longitudinal axis of the bearing body 20. This is shown in Fig. 1 to the right of the longitudinal axis of the bearing body 20. Due to the inclined arrangement of the bearing body 20, the first gimbal axis 24 forms an acute angle a with the roll axis (FIG.
3). A section perpendicular to the section on the right-hand side is shown to the left of the longitudinal axis of the bearing body 20. It can be seen there that an outer frame, which is generally designated by 26, is pivotably mounted on the inner frame 22. The outer frame 26 is pivotally mounted about a second cardan shaft 28, which runs perpendicular to the first cardan shaft 24. If the first gimbal axis 24 in the right part of FIG. 1 runs in the paper plane of FIG. 1, then the second gimbal axis 28 runs perpendicular to the paper plane of the right side of FIG. 1 in relation to this.
A viewfinder system 30 in the form of an imaging optical system sits on the outer frame 26. This viewfinder system 30 contains an annular hollow mirror 32 which is mounted with its central opening on the outer frame 26. The outer frame 26 has a dome part 34. The dome part 34 carries webs 36 which carry a weakly convex secondary mirror 38 facing the concave mirror 32. The dome part 34 forms a holder 40 for a lens optic 42. Parallel incident light from an object scene lying at infinity is reflected by the concave mirror 32 onto the secondary mirror 38 and directed by this onto the lens optic 42. The optical system creates an image of the object scene on a detector 44.
The detector 44 is cooled in the usual way by a Joule-Thomson cooler 46 which is arranged inside the sleeve-shaped bearing body 20. On the back of the secondary mirror 38, an inertial sensor unit 48 is arranged similarly to DE 195 38 886 AI.
The cardan axis 24 and 28 and the roll axis 18 intersect at a common intersection 50. The structurally fixed detector 44 is arranged in the region of this common intersection 50. The dome 12 is around the intersection
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50 curved. Around this intersection 50, the outer gimbal 26 is mounted so that it can be given away on all sides. In this arrangement, the gimbals 22 and 26 are arranged within the viewfinder system 30. The viewfinder system 30 sits on the outer gimbal frame 26. One therefore speaks of an "inner gimbal system".
The table 16 can be rotated about the roll axis by a servomotor 52. At the table 16 sit 54 on a spherical surface 54 magnets 56 with a spherical shell-shaped magnetic yoke 58. The magnets 56 generate a radial magnetic field. Flat coils 60, which are connected to the outer gimbal frame 26, are seated in this radial magnetic field. These magnets 56 and flat coils 60 form torque generators 62 which act directly on the outer gimbal frame 26. This arrangement corresponds in principle to the torque generator arrangement according to EP 0 766 065 B1 and US Pat. No. 5,892,310, the disclosure of which is incorporated by reference.
The finder system 30 defines an optical axis 64. The inertia sensor unit 48 controls the torque generators 62 in such a way that they stabilize the finder system 30 in space and decouple it from the movement of the missile. After suitable signal processing, the detector 44 of the viewfinder system 30 delivers storage signals which reflect the storage of a target detected by the viewfinder system from the optical axis 64. These storage signals are applied to the inertial sensors of the inertial sensor unit 48, so that they are precessed in accordance with the storage signals. The stabilized position of the optical axis is then tracked to the target.
2 schematically shows the stabilization of the finder system 30 in space, the alignment of the optical axis 68 to the target.
The inertial sensor unit 48 stabilizes the finder system 30 in space. The inertial sensor unit 48 controls the torque generators 62 in the usual way. If there is a deposition of the line of sight to a target detected by the finder system 30 from the optical axis 68, then the deposition signals delivered to the finder system 30 are onto the inertial sensors
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Inertia sensor unit 48 is switched on and precessed in such a way that the stabilized optical axis 68 is tracked to the target.
As is further shown in FIG. 2, the frame angles of the gimbal system are determined by angle transmitters 70. When these frame angles approach the stop position of the inner frame, the roll servomotor 52 is controlled by the control device 72 in one or the other direction of rotation.
The roll servomotor 52 then rotates the table 16 with the entire gimbal system and the viewfinder system 30 about the roll axis in such a way that the line of sight is again in the adjustment range of the gimbal system.
FIG. 3 illustrates the effect of the inclination of the first gimbal axis 24 to the roll axis 18. The first gimbal axis 24 forms an angle a with the roll axis 18. In Fig. 3 it is assumed that the inner gimbal 22 is in its central position. The plane of the inner gimbal 22 is then perpendicular to the paper plane in FIG. 3. The outer gimbal 26 can then be adjusted between the two stop positions about the second gimbal axis 28 perpendicular to the paper plane, which positions 64 A and 64 B are symmetrical to a central position 64 M correspond to the optical axis 64.
The angle between the stop position 64 B and the roll axis 18 is ss + 90 -ot. At an acute angle of 60 between the first gimbal axis 24 and the roll axis 18, the maximum tilt angle of the finder system 30 relative to the roll axis 18 is approximately 70 in the embodiment shown. The viewfinder system 30 can thus in the illustrated position of the table 16 an asymmetrical solid angle to the roll axis 18 up to z. B. 70 in the paper plane on the right side of FIG. 1. In the azimuth direction, the solid angle is limited by the stop position of the outer gimbal frame 26. Areas on the left in FIG. 1 are also not recorded because of the asymmetry.
As described, when the inner frame 22 approaches a stop position, a rotation about the roll axis 18 is initiated and the solid angle limited by the stop positions tracks the line of sight to the target such that the line of sight is always in the area of the solid angle,
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in which the optical axis 64 of the viewfinder system 30 can be aligned with the target by the gimbal system.
The optical axis 64 of the finder system 30 can thus be aligned with a target within a solid angle of 70 around the roll axis 18.
FIG. 4 shows a longitudinal section through a seeker head 15. As in FIG. 1, a bearing structure 20 is arranged inclined by a wobble angle of (90-a) to the roll axis 18. The bearing structure 20 is rotatably supported about its longitudinal axis or wobble axis 21 and the roll axis 18 by the bearings 23 and 25, respectively.
5 shows a longitudinal section through the search head 15 according to FIG. 4. To clarify the configuration of the wobble axis 21 and the fixing of the inner frame 22 and outer frame 26 (both not visible in the figure) by means of the fixing means 27, 29 with respect to their position in relation to the roll axis 18 components of the pitch-yaw region are not shown. The fixing means 27 is a gearwheel integrated coaxially to the missile longitudinal axis or roll axis 18 in the missile structure 10. The fixing means 29, also a gearwheel, is arranged at the wobble angle of (90 -a), which corresponds to the drawing 20, on the pitch-yaw gimbal system consisting of the inner frame 22 and outer frame 26 with the degree of freedom of rotation of the wobble axis 21.
The two gear wheels 27, 29 have different radii and a profile shift matched to them.