Method for conducting fire against target, fire control system and combat system

Abstract

The invention consists of a method for directing fire against targets where the position of at least one protected object is known, and including the following method steps: i.) measuring the position of the target, ii.) estimating the position of the target, iii.) estimating the speed of the target, iv.) categorizing the target, v.) calculating the trajectory of the target, vi.) deciding whether the target is heading towards a protected object or is passing by. The invention furthermore consists of a fire-control system for directing fire against an air target comprising at least one sensor, in order to measure the position of the air target as a function of time. The invention furthermore consists of a combat system including a firing device.

Description

Method for conducting fire against target, fire control system and combat systemTECHNICAL FIELD

[0001] The present patent application relates to a method for directing fire against targets, wherein the invention further relates to a fire-control system and a combat system.BACKGROUND OF THE INVENTION, PROBLEM AREA AND STATE OF THE ART

[0002] When combating a moving target with unguided or guided projectiles fired from barreled weapons, the projectiles must be fired at the points where the target will be when the projectiles reach it, or at points close to where the target is located. Such points, usually called forward points, must be predicted. In this context, a prediction refers to an estimate of the target's position a brief time into the future. The estimate is based on knowledge of the target's previous positions and on a hypothesis about how the target will behave in the future.

[0003] An estimate of the target's current position and state of movement based on continuous data flow from an ongoing measurement of the target's direction is referred to as an estimate of target data.

[0004] Estimation and prediction take place in parallel, at least up until the point when a combat process commences. At least one sensor is used for purposes of following and measuring the position of the target. The target’s current position and speed are estimated with a basis in measured data from this sensor. A predictor then calculators, with a basis in estimates and hypotheses, how the firing weapons are to be aimed.

[0005] An example of a method and device for directing fire against airborne craft is provided in patent document EP 3004786 (A1 ). The patent documentshows that forward points are calculated on the assumption that the airborne craft intends to travel towards the launch device, i.e. its own position, after which control laws are applied to the airborne craft so that said own position can be reached.

[0006] The problem with existing solutions according to the above-mentioned document is that, in cases where the airborne craft does not steer towards said own position, no method has been demonstrated to improve the possibility of operating against other targets.

[0007] Additional problems which the present invention seeks to solve will become apparent in connection with the following detailed description of the various embodiments.PURPOSE AND FEATURES OF THE INVENTION

[0008] The purpose of the present invention is to improve the ability to estimate whether a threat is of an incoming or a passing type. The trajectory of incoming threats can be predicted, and thus accurate forward points can be calculated when the action, such as air defense artillery or missiles, is used to combat incoming threats.

[0009] Trajectory prediction is achieved by calculating the trajectories an attacking craft may follow. The calculation is based on known knowledge of the positions of the protected objects, estimated knowledge of the craft's current position and speed as well as knowledge and / or an assumption about the control laws an attacking craft may apply to hit one of the relevant protected objects. When predicting a craft's future position, hypotheses about the control law that gives rise to the craft's trajectory can thus be used, as is described in greater detail in patent application SE 1 330 063 A1 , which is incorporated into this application in its entirety by way of reference.

[0010] The invention relates to a method for conducting fire against targets where the position of at least one protected object is known, and including the following method steps: i.) measuring the position of the target as a function in the fire-control system, ii.) estimating the position of the target in the fire-control system, iii.) estimating the speed of the target in the fire-control system, iv.) categorize the target in the fire-control system, v.) calculating the trajectory of the target in the fire-control system, vi.) deciding, in the fire-control system, whether the target is heading towards a protected object or is passing by.

[0011] According to additional aspects of the method for directing fire towards a target, the following applies: that once a decision has been reached about following the target, the following additional method steps are included: vii.) calculating forward points along the predicted trajectory, viii.) aiming a firing device towards the forward points.

[0012] categorizing the target as any of the following:- naval target robot,- aerial target robot,- helicopter,- surface vessel,- UAV- a different target object.

[0013] that the target's trajectory is calculated by:1 .) calculating which accelerations the target needs to apply to hit the protected object,2.) employing a model of the target's steering law based on the categorization of the target,3.) predicting the future trajectory of the target based on the position of the protected object, the estimated position of the target, the estimated speed of the target, the estimated acceleration of the target.

[0014] that an operator can, after aiming a barreled weapon at forward points, decide to engage the target.

[0015] that if the target is determined to be of a passing type, target tracking of the current target is terminated, and measuring of a new target may be commenced.

[0016] that the position of the protected object is the own position of air defense artillery.

[0017] The invention furthermore consists of a fire-control system for directing fire against a target comprising at least one sensor, in order to measure the position of the target as a function of time, whereas a method of fire control as described above is utilized.

[0018] The invention furthermore consists of a combat system comprising a launch device, whereas a fire-control system as described above is applied.

[0019] According to further aspects of a combat system, the following applies:

[0020] that the firing device is a system comprised of a barrel-based canon.

[0021] that the firing device is a firing device for missiles.THE ADVANTAGES AND EFFECTS OF THE INVENTION

[0022] The advantage of the present invention is that the firing platform can adapt its manner of operation by; 1 . if an incoming threat (also referred to as atarget) is determined to be heading towards the own platform, also referred to as being incoming, calculate the forward points that make it possible to direct the action so that the projectile, which may be guided or unguided, which are shot off upon firing, will get so close to the attacking threat that the action can be achieved, alternatively 2. If an incoming threat is not determined to be on its way to the own platform, also referred to as not being incoming or passing, adapt their action, for example by ceasing to combat the threat in order to save ammunition and / or switching to another incoming threat in order to start combating another incoming threat that, based on the threat's current position and speed, may still pose a threat to the firing platform.LIST OF FIGURES

[0023] The invention will be described below by reference to the figures that are included there:Fig. 1 shows a flow schematic of a method for directing fire against a target according to one embodiment of the invention.Fig. 2 shows a block diagram of a device for combating targets according to one embodiment of the invention.Fig. 3 shows target areas for a target according to one embodiment of the invention.Fig. 4 shows the trajectory of a target according to one embodiment of the invention.DETAILED DESCRIPTION OF EMBODIMENT

[0024] An attacking guided craft, also referred to as a target, intends to damage an attack target or a protected object, depending on the perspective from which the attack target or protected object is viewed. Combating the target means that the target is affected so that it can no longer damage the protected object towards which the target is traveling.

[0025] A system designed to engage targets using barreled weapons and unguided or guided projectiles can be considered to consist of three parts: fire control, weapons, and projectiles. Such a system will henceforth be referred to as air defense artillery. Unguided projectiles refer to various forms of projectiles, such as grenades and rockets, which are intended to be used for combating targets. When guided projectiles are utilized, projectiles with guidance capability are used, after which additional systems for communication with the guided projectiles are added. The guided projectiles can also be autonomous and outfitted with, for instance, target seekers that enable them to guide themselves towards the target. Furthermore, targets can be combated with missiles.

[0026] Fire control that constitutes part of an air defense artillery system includes one or more sensors, as well as several methods for handling and evaluating sensor data. The sensor or sensors that are included in, and used by, the fire line will henceforth be referred to as sights.

[0027] Refined information from the sight is used to control the alignment of both sight and weapon.

[0028] A com bat process can be considered to consist of a number of activities. Some activities must take place in sequence while others can take place in parallel.

[0029] In figure 1 , a flowchart for a method in a fire-control system 1 is described. When combat begins, start 2 in figure 1 , the sight is aimed at the target to be combated. This is usually made possible by an external unit, for example a surveillance radar, continuously delivering information about the target's position as a function of time. The external unit can, for example, be arranged on the platform where the firing system is arranged, for example a ship. This external device is called the guidance device. The procedure is called guidance 3.

[0030] The position of the target is preferably specified in an orthonormalized, horizontal, north-oriented, Cartesian coordinate system, the origin of which is preferably known for all common systems for acting against targets.

[0031] In parallel with aiming the sight at the target, the barrel, or the action device, can be aimed at a preliminarily calculated forward point, the position of which is based on data from the aiming unit. In this way, the time for firing the barrel is reduced when a more accurate forward point has been calculated because the preliminarily calculated forward point will be close to the more accurate, later calculated forward point.

[0032] Completed guidance means that the sight may be able to, itself, measure the position of the target. However, it is not certain that the sight will be able to detect the target immediately - even though it is correctly aimed. Assuming that the target constantly gets closer, the probability of the sight being able to detect the target increases. The even that takes place when this occurs is called target capture. Target capture is the start of a new sequence called target tracking 4. The sight then controls its own line of sight so that the line of sight follows the target.

[0033] When target tracking 4 has been established, target measurement 5 starts. The sight now tries to measure both direction and distance to the target. It is not guaranteed that the sight will be able to measure the distance to the target immediately when a target measurement 5 is started. However, sooner or later, the sight will begin delivering distance data. Meanwhile, the position of the target and the preliminary forward point can be calculated by combining the angle data from the sight and the range data from the guidance device.

[0034] When the sight can finally generate both direction data and distance data, no guidance data is longer required for purposes of controlling the sight and barrel. However, guidance data may be used for other purposes.

[0035] When the sight measures the position of the target, during target measurement 5, it usually achieves higher frequency and better accuracy than the guidance sensor is capable of This is the basic reason why two types of sensors are used, surveillance sensors and fire-control sensors.

[0036] The raw data from a sight is usually in the form of spherical spatial coordinates, i.e. two angles and a distance. This data is additionally labeled with the time at which the spatial coordinates were valid. Raw data from the sight is used in the following way: The measurement data is transformed into a horizontal, north-oriented, Cartesian coordinate system and thereby takes the form of three Cartesian spatial coordinates and a time indicating when the coordinates were valid. The spatial coordinates are denoted by x, y, z and the time when the coordinates were valid is denoted by t. Each individual piece of measurement data thus consists of four scalar values (x, y, z, t). The weapon, which will later be used, knows its own position and orientation in the coordinate system used by the sight. Sight and weapon also use common time.

[0037] The fire direction process saves measurement data the age of which does not exceed a certain value, for example in the order of three seconds, in a buffer. When the buffer is full and a new piece of measurement data is registered, the measurement data with the oldest validity date is deleted.

[0038] The measurement data is used for an estimation of the target's position and speed 6. By utilizing knowledge of the position of the protected object that the target is intended to hit, the target's trajectory can be predicted with greater accuracy. The current position and velocity of the target can be estimated from the raw data, for example in the manner already described. The target's future acceleration can then be predicted, calculation of the target's future acceleration 7 in figure 1 ,

[0039] By knowing the position of the protected object and predicting the target's future acceleration, the acceleration that the target's control system will request to utilize can be calculated. By using information about the various categories of equipment, such as mobile robots, aerial robots, helicopters, surface vessels, UAVs or other target objects, improved knowledge of the target's steering automation can be achieved. The categorization is based on, for example, the target's estimated position and speed, where speed can determine whether the target is a robot, helicopter, UAV or ship, and where position can determine whether the target is a naval target robot, air target robot or a surface vessel. Overall, the estimation of position and velocity can enable improved categorization. In the event that the target object cannot be categorized as a naval target robot, air target robot, helicopter, surface vessel, or UAV, the target may be categorized as a different target object.

[0040] It is possible, for instance, that for each target object, as to the interval that the target can assume for its acceleration. In the case of another target object, no assumption can be made as to the interval that the target can assume for its acceleration, thus making the prediction of the target's future acceleration take longer. If the target object is categorized as a surface vessel, this is only relevant when it comes to planar accelerations, as a surface vessel cannot move in space. Furthermore, it can be assumed that a naval target robot and an air target robot have greater capabilities of acceleration than, for instance, a helicopter or a UAV. Furthermore, the combating of the target, based on the categorization of the target, may be adapted. For example, the setting of the proximity fuze can be adjusted based on the target object's categorization where, for example, a UAV has a smaller signature than a helicopter, and the sensitivity of the proximity fuze can be adjusted accordingly.

[0041] By applying control laws for the target, the forward point can be calculated in the step Calculation of target path and forward point 8. Patent document SE 1 330 063 A1 specifies how these calculations are carried out in detail, and is incorporated by way of reference.

[0042] In step Incoming? 9, a determination is made regarding whether the target is of an incoming or passing type. If the target is determined to be incoming and when the forward point is calculated, a choice can be made as to whether the air target is to be combated in step Combat target? 10. If this is the case, a process to combat the weapon is executed, in step Fight the target 11 , preferably with barrel-based weapons.

[0043] It is now neither necessary nor desirable to always open fire as quickly as possible. On the contrary, it can be advantageous to wait and make sure that the air target in fact passes through predicted forward points at predicted times. Namely, it is entirely possible to predict more than one target trajectory at the same time. Thus, in accordance with the above description, it is possible to predict a number of different trajectories for a number of navigation constants (e.g. 3, 4, 5, 6, 7) and then compare the predicted trajectories with the trajectories that are actually observed. In this manner, it becomes possible to determine which navigation constant the air target seems to be using, and thus it becomes possible to deduce which one of the predicted target trajectories is the most accurate one.

[0044] In the event that the target is not determined to be of an incoming type, an assessment is made as to whether the best course of action is to replace the target, which takes place in the step Replace the target? 12. If the probability of being able to combat the target is determined to be low, for example if the target is at a long distance and cannot be approached based on the calculated trajectory for the target, then a choice can be made to start following a new target or simply wait for a possible future target. If instead combating the target is determined to be possible, even though the target is of a passing type, the choice can be made not to change the target and thus proceed to step 10, Combat the target? If this is the case, a process to combat the weapon is executed, in step Fight the target 11. In the step Combat the target 11 , ammunition type and settings for the ammunition, such as sensitivityto proximity fuzes, different time aspects and more, can be adjusted based on a categorization of the target.

[0045] An air defense artillery system 20, as shown in Figure 2, including a type of fire control 21 , one or more weapons 26 and projectiles 27 that can be fired at targets. The system 20 receives input from an external surveillance sensor 22, which can search very large volumes with great depth at the expense of accuracy and measurement frequency. The air defense artillery system 20 includes a fire-control sensor 23 which, after training, can measure the position of the individual target in a small sector with limited depth, but with high accuracy and high measurement frequency. The calculation unit 25 is used to calculate the forward points towards which the weapon 26 should be aimed. The fire direction 21 may also include a protected object database 24 that contains positions for a number of protected objects that can be found in the immediate area around the air defense artillery system 20. Weapons 26 and projectiles 27 can also constitute missiles.

[0046] Figure 3 shows a target area 100 for a target heading towards one of several protected objects. Along the target's journey towards the protected object 104, a number of protected objects 105, 106, 107 will be passed or end up outside the area towards which the target can maneuver. When it reaches point 101 , the target can be guided to all protected objects 104, 105, 106, 107 within target area C. When the target continues its journey towards the protected object, the target will be in point 102 within a certain time. It will then find itself in a location where it could possibly combat all protected objects 104, 105, 106 within target area B. At this point, point 102, a firing platform, arranged on protected object 107 outfitted with a fire control method, can determine that the target is of a passing type, after which the firing platform with which the protected object 107 is outfitted is able to interrupt target tracking and wait for new guidance data to a new target from, for example, a surveillance radar. The target then continues to point 103, target area A, where protected objects 105 and 106 are no longer possible to fight. Thus, only protected object 104 ispossible to fight. At this point, point 103, a firing platform arranged on protection objects 105 and 106 outfitted with a fire control method can determine that the target is of a passing type, after which the firing platform arranged on protected objects 105 and 106 can interrupt target tracking and wait for new guidance data to a new target from, for example a surveillance radar. Thus, it becomes clear that the target's likely final target is protected object 104. With the likely protected object now having been identified, forward points are able to be calculated with a greater degree of reliability.

[0047] Figure 4 shows an air target’s trajectory 1000 towards a protected object 1001. The air target flies towards the protected object 1001. The air target is detected by a surveillance sensor when it passes point 1002. The surveillance sensor then signals a fire-control sensor. Somewhere between points 1002 and 1003, the fire-control sensor detects the target and begins to follow and measure the target’s position and speed. At point 1003, the target could possibly commence a chance of course, e.g. in an attempt to locate target object 1001. At point 1004, the target's chance of course is finalized. At point 1005, the target begins to follow a steering law which aims to steer the craft to hitting the protected object 1001. When the target passes point 1006, the fire control is able to start predicting forward point 1007. The prediction is based on data from the fire-control sensor and a hypothesis regarding which steering law the target is utilizing. The barreled weapon is aimed towards point 1007 and a combat process may possibly be initialized once an operator makes a decision to combat the incoming target.ALTERNATIVE EMBODIMENTS

[0048] The invention is not limited to the embodiments specifically shown, but can be varied in different ways within the framework of the claims.

[0049] For instance, it is clear that the elements and details included in the method for directing fire towards targets, such as the number of sensors, firingdevices or systems, are to be adapted to the weapons system, platform or other construction properties which currently apply.

[0050] It is to be understood that the method described above for conducting fire against targets can be applied to basically all unguided or guided craft and systems including aircraft, unmanned flying craft and missiles, surface vessels or underwater craft that are possible to measure.

Claims

Claims1. Method for conducting fire against targets characterized in that the position of at least one protected object is known and that the following method steps are included; i.) measuring the position of the target as a function of time by means of a sensor, ii.) estimating the position of the target in a fire-control system, iii.) estimating the speed of the target in the fire-control system, iv.) categorizing the target in the fire-control system, v.) calculating the trajectory of the target in the fire-control system, vi.) deciding, in the fire-control system, whether the target is heading towards a protected object or is passing by.

2. Method for directing fire towards targets according to claim 1 , characterized in that, when the following of the target is decided by an operator, the following additional method steps are included; vii.) calculation of forward points along the predicted trajectory, viii.) aiming a firing device towards the forward points.

3. Method of conducting fire against a target according to any of the above requirements characterized in that the target is categorized as one of;- naval target robot,- aerial target robot,- helicopter,- surface vessel,- UAV,- other target object.

4. Method for conducting fire against targets according to any of the above claims, characterized in that the target's trajectory is calculated by:1.) calculating which accelerations the target needs to apply to hit the protected object,2.) employing a model of the target's steering law based on the categorization of the location,3.) predicting the future trajectory of the target based on the position of the protected object, the estimated position of the target, the estimated speed of the target, the estimated acceleration of the target.

5. Method for conducting fire against targets according to any of the above claims, characterized in that an operator can, after aiming a barreled weapon at forward points, decide to combat the target.

6. Method for directing fire against a target according to one of the above claims, characterized in that if the target is judged to be of a passing type, measurement of the current target has been completed, and measurement of a new target can begin.

7. Method for conducting fire against air targets according to one of the above claims, characterized in that the position of the protected object is an air defense artillery’s own position.

8. Fire-control system for directing fire against a target comprising at least one sensor with the purpose of measuring the position of the target as a function of time characterized in that the method for fire control according to one of claims 1 to 7 is applied.

9. Combat system including a firing device, characterized in that a firecombat system according to claim 8 is utilized.

10. Combat system according to claim 9, characterized in that the firing device is a barrel-based canon system.

11. Combat system according to claim 9, characterized in that the firing device is a firing device for missiles.

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