EP1103779A1 - Method for correcting a target related ballistic trajectory - Google Patents

Abstract

The error correction method uses on board GPS satellite (27) trajectory measurement (24) to select aerodynamic braking (26) with parametric disturbance correction (19) to steepen the projectile (17) path towards the minimum range error bound (23) path (21) which has been aimed at the target (13).

Description

The invention relates to a method according to the preamble of claim 1.

Such a method is known from WO 98/01719. It is based on a satellite navigation device on board the projectile the one currently flown Determine trajectory and from a comparison with a target-optimized Flight path when reaching a path point derived from the comparison aerodynamic Braking devices for the most accurate correction possible to release the subsequent trajectory. Problematic for practical implementation is, however, that the numerous external factors influencing a trajectory act on the trajectory even after the brake means have been triggered and therefore the corrected trajectory then not for the precise delivery of the mechanism of action leads in the projectile.

It is known from EP 0 138 942 B1, for example from the gun, by means of radars to locate a target and in the fire control computer elevation and charge for something then to determine the ballistic trajectory that goes beyond the target measure the rate of launch of the projectile from the weapon barrel and shortly afterwards by means of radars a current position of the projectile relative to the To determine the gun. From a comparison of this current position with the The target position based on the calculated ballistic trajectory becomes the actual one expected destination storage, and finally derived from when Projectile aerodynamic braking effects such as the opening of brake flaps or the blasting of an aerodynamic projectile tip should be activated in order to the remaining trajectory due to the new aerodynamic conditions to shorten and thus reduce the storage of the target. Here too again finds only a comparison of a real and a given ideal trajectory instead of to determine when a braking time has been reached, so that again the time of initialization for the brake means depending on external influences is subject to errors and then the subsequent changes Trajectory influencing variables inevitably lead to an additional Lead destination storage.

Such a corrective measure of the braked transition from an initial one After all, there is a trajectory in an optimized trajectory according to its apogee much cheaper than installing the target sensor, control system and control loop for an automatic, target-seeking final approach of a projectile. On the other hand is given the high initial projectile speed the determination of the real trajectory from the measurement of initially more current ones Path points very imprecise. The actual curve flown should be very well known for the braking maneuver to shorten the trajectory after apogee to optimally schedule in order to reduce dispersion in the target area can. Reliability is also a problem with a ground-based process a communication link for the transmission of the brake release time or directly from the brake command from the fire control computer to the projectile, because, given its high speed, it is at times in one piece ionized, atmospheric envelope impairing a radio connection can.

In recognition of these circumstances, the present invention is based on the object that is promising in itself, but still too for practical needs to further develop inaccurate methods of the generic type in such a way that a shortening of the trajectory due to an increase in aerodynamic Braking torque can achieve a much more precise target acquisition. This The object is achieved in that the specified in the main claim essential process steps can be realized.

The solution according to the invention is therefore based on what is known per se the much larger longitudinal scatter of a ballistic compared to the transverse scatter or quasi-ballistic projectile by reducing the stopping point first moved behind the measured target position and then this path is abbreviated. But that relocation now takes place only so far that the transition trajectory the projectile after decelerating taking into account a current one Error budget leads theoretically to the target on the shortest trajectory; According to the invention, this given error budget is as long as possible along the Path curve up to the braking torque from a comparison with that for certain Error specifications theoretically predicted trajectory is determined.

The projectile can e.g. to an unpowered, from a mortar or storey from a howitzer, but also about an artillery missile with their initially quasi-ballistic to increase the range Trajectory acting rocket engine. The real transition trajectory into which the projectile then from its initial trajectory using the aerodynamic Braking effect is swung in between the flattest or shortest (minimum) and the highest or longest (maximum) trajectory of the current Spreading fan and can in principle by braking into the shortest, i.e. into the trajectory leading straight to the destination.

For the determination of the current trajectory is not necessarily on the right inaccurate and technically unreliable trajectory determination from the gun used here. Rather, as is known per se, the initialization point intended for the braking maneuver on board the projectile, i.e. without to be dependent on a data connection to a ground station. For this purpose the projectile is again to be determined with a satellite reception device the actual initial trajectory. Deviating from The braking maneuver does not become a generic state of the art triggered when a predetermined path point is reached, but according to the invention the initial trajectory is as long as possible compared with the theoretical launch curve for as many path points as possible. From the structure of the path deviations determined from it, from system-related Specifications and preferably additionally from sensory measurements, for example on board the projectile and / or from the ground, in particular according to DE 4120367 A1. the current disturbances are recorded parametrically. They are special Wind directions and strengths at different heights, but also about Failure budget of the launcher (known transverse and vertical direction inaccuracies of the gun) and influences depending on the environment Launch charge intensity. With such knowledge, you can be right precise statements about the interference effects using the usual external ballistic Predict approaches that are still active even after the brake is triggered the transitional trajectory flown subsequently to act on these to be expected Error effects in advance by correcting the braking time to compensate as much as possible. To get as much information as possible about the destination of the current error budget, the braking time is as possible late. So it is ultimately not defined depending on the start of the projectile, but depending on the remaining flight time until the theoretical reaching of Target. It is therefore determined backwards in time, in a way counter to the temporal movement along the path.

To minimize the flight time for contacting the navigation satellites from Projectile need, especially the determination of the real trajectory The projectile will be deployed as soon as possible after the start of the projectile information about the error budget that is already known arithmetic, i.e. currently ideal trajectory, as well as the resulting expected satellite contacts. This can be done very much from the projectile quickly to at least some of the navigation satellites above the horizon accessed and quickly reliable information on the actual (Real) trajectory curve, i.e. also about its deviation from that predicted by calculation can be obtained from the actual current error influences close.

The more current path points on board the projectile using satellite navigation can be measured, the more precise the path curve bs is for insertion of the braking maneuver beyond the apogee, the more precise it is the expected storage of the conventionally measured and The target point transmitted on board in the projectile can be determined. So that leaves the ideal initialization point for initiating the braking process, i.e. for entry into the transition trajectory determined by the new aerodynamic conditions from the real trajectory that is too far specified into the minimal, precise Trajectory depending on the remaining flight time to the target area accordingly predict exactly. Because, on the other hand, this is as late as possible Braking timing can be determined accurately, the satellite bearing for updating the knowledge of the real trajectory up to the immediate temporal Close to the activation point for the braking maneuver, i.e. correspondingly long also continue beyond the apogee, which leads to another Improve the determination of the externally influenced real trajectory as far as possible close approach to the goal and thus to knowledge about the interference leads right up to the goal. If so on the so through continuous update very precisely determined real trajectory for the currently given The last possible initialization point for entering the decelerated is influenced by errors Transitional trajectory to approach the minimal trajectory immediately the forthcoming braking maneuver is imminent, for example by issuing it of braking elements or blasting off of the aerodynamic projectile tip triggered and therefore the target acquisition with great reliability on the final approach on the minimal, at least on a very close to the target trajectory reached.

To the computing effort for determining the optimal (latest possible) It is advisable to minimize the time the brakes are released on board the projectile Path coordinates of a fan of expected, also below Wind or other disturbances shifted from the pure throwing parabola, real trajectories between the maximum and minimum trajectories as e.g. Look-up tables, for example, from the fire control computer to the processor on board the Projectile stored; and also as a trigger curve the result of the ideal So the latest possible initialization points over the remaining term of the respective Trajectory of this fan. For those then from satellite navigation very much now only needs precisely defined current, real trajectory within this subject the imminent intersection of the currently flown real ones Trajectory to be predicted with that release curve, and then the brake release for the transition to the precise, minimal trajectory.

Additional alternatives and further training as well as further features and advantages the invention result from the further claims and from the following Description of one in the drawing limited to the essentials not to scale and highly abstracted preferred implementation example for practicing the method according to the invention. The only figure of the Drawing shows in longitudinal section the principle of moving a ballistically started Projectile from a gun to a target along the final approach from the real into the minimal, ie target-optimized decelerated trajectory; with determination the initialization point for the transition trajectory from a continuous satellite-based Path determination on board the projectile.

Depending on the pre-enlightened direction and distance 11 from a gun 12 to a target 13 in a fire control computer 14 azimuth alignment, elevation 15 and propellant charge power (i.e. the theoretical exit speed 16) destined for the ballistic trajectory 18 of a projectile 17 into the target area. This The calculated exit trajectory 18 goes into a trajectory 20 after apogee that between a minimum trajectory 21 and a maximum trajectory 22 for a certain budget in the environment of the actually acquired Target 13 lies within a certain longitudinal scatter 23 of the possible ones Impact points in the target area. Due to systematic and operational reasons Error influences such as inaccurate elevation 15, actually deviating from the specification Departure speed 16 and, for example, height-dependent on strength and in the direction of different wind influences 19, the real trajectory 20 is correct actually does not match the one from the calculated parabola for the Path curve 18 follows, but increasingly deviates more or less from it. Because a trajectory 20 is not stretched, only due to aerodynamic braking influences can be shortened, the projectile 17 with an aerodynamic braking device equipped, in which it is known as such about fold-out Braking surfaces or a releasable flattened projectile front can, cf. also the radial, stretchable brake sail to shorten the trajectory according to DE 3 608 109 A1.

A real trajectory 20 is for the actually existing braking system 26 and for certain interference influences an ideal initialization time in relation to the remaining flight time to the destination 13 24 assigned from which straight from the real trajectory 20 can swing around in such a transition trajectory 25 that this increasingly the minimal trajectory 21 nestles and in theory ultimately exactly leads to goal 13. The earlier this initialization point 24 lies on the real one Trajectory 20, the further it is without the braking corrective action in the target area level would be from target 13, the higher the trajectory 20 is. The means that for a fan of possible real trajectories 20 a consequence of ideal initialization points 24 can be represented as a trigger curve 28 which (as from the drawing) something compared to a family of curves of real trajectories 20 is pivoted, which is the total of the real trajectories 20 between minimum and maximum trajectory 21-22 intersects once. The different Interfering influences (such as wind data 19) can be differentiated by a group inclined fan of trajectories 20 and / or by a crowd different Parameterize tripping curves 28.

This can be the imminent achievement of the under the current fault conditions for a certain start orbit curve 18 ideal initialization point 24 can be predicted exactly because the disturbed real trajectory 20 is right is exactly known.

The determination of the currently real trajectory 20 (and from this the determination the initialization point 24) is reached on board the projectile 17 even over the longest possible flight route in order to maximize the real impact many error influences on the trajectory 18 into the trajectory 20 to capture. The orbit determination is carried out with the aid of satellites, i.e. via Receiving the position information from those currently recorded on board the projectile 17 Navigation satellites 27 based on their known orbital data, such as from satellite navigation using different systems of location satellites as such well known. For this purpose, the spin-stabilized projectile 17 is preferably included a scanning of the projectile 17 rotating against the swirl on its outer surface surrounding antenna elements equipped to ensure interference-free To enable direct reception, i.e. disturbing ground reflections from the satellite radiation to hide, as explained in EP 0 840 393 A2.

In order to be able to switch to the satellites 27 as quickly as possible, that is to say one as possible early dense sequence of real path coordinates for determination the actual trajectory 18 and the resulting trajectory 20 received, the projectile 17 from the fire control computer 14 at the start for the arithmetically predetermined launch trajectory 18 expected values with regard to the Given positions of presumably receivable satellites 27, then after the start on board with continuous updating. Moreover are to predict the initialization point 24 in the processor on board the Projectile 17 sequences of initialization points 24 possible for disrupted subjects real trajectories 20 are stored as a fault-dependent family of trigger curves 28.

If now taking into account the current interference on the by means of Satellite navigation quite accurately determined real trajectory 20 of the stored ideal initialization point 24 is reached, the braking device 26 is activated and the previous real trajectory 20 with pivoting into the transition path 25 ins Leave goal 13 inside.

So without the technological effort for automatic target search control the inevitable path scattering of projectiles brought ballistically into the target area 17 noticeably reduce and thus the accuracy of hits significantly increase, the minimum trajectory 21 - taking into account the error budget the weapon 12 and the expected external factors such as height-dependent Headwind 19 on a real trajectory 20 - through the previously explained Target position 13 relocated so that all real trajectories 20 to the maximum Trajectory 22 of this total error budget lie behind target position 13. Then the projectile 17 descends into the target area from the current, real one Trajectory 20 out to the minimal trajectory 21, that is to the target position 13 shortened by releasing an aerodynamic braking effect. For that, on the real trajectory 20 the reaching of the dependent on the theoretical remaining flight time optimal initialization point 24 for the aerodynamic braking device determined on the projectile 17 by the real trajectory according to the invention 20 over as long a route as possible until just before the intersection an environmentally dependent trigger curve 28 - and therefore up to No more capturing all the actual influences of errors - by means of satellite navigation is continuously measured. So the actual approach to the Intersection with the trigger curve 28, that is, the sequence of optimal initialization points 24-24 for the subject of real trajectories 20/20, determined from which out a braked transition trajectory 25 to the minimal trajectory 21 nestles through the target position 13.

Claims (4)

Process for correcting the expected target placement of the satellite-based trajectory measured on board a ballistic or quasi-ballistic projectile by increasing its aerodynamic drag coefficient to swing out of the initial trajectory into a steeper transition trajectory to the target,
characterized,
that sensory and / or external interference influences on the course of the path curve are taken into account in a predictive determination of the upcoming real trajectory beyond the target, and that for the real trajectory to be expected accordingly, taking into account those influences an initialization point as close as possible to the target for increasing the drag coefficient for entering a transition trajectory for swiveling into the target-specific minimal trajectory is determined. Method according to claim 1,
characterized,
that the trigger curve of a sequence of initialization points is stored in the projectile for a prediction-dependent subject of real trajectories between the minimum trajectory to the target and a maximum trajectory behind the target and the impending intersection of the trigger curve with the measured real trajectory for triggering the braking device is determined from the current satellite navigation becomes. The method of claim 1 or 2,
characterized,
that interference-dependent families of curves for real trajectories and / or for triggering curves are stored in the projectile. The method of claim 1, 2 or 3,
characterized,
that the projectile is given initial positions at the start of the anticipated real trajectory in accordance with the contacts to navigation satellites to be expected for the orbit measurement.

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