Patent Publication Number: US-8989449-B2

Title: Method and arrangements for firing a fire arm

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the national phase under 35 U.S.C. §371 of PCT/SE2010/050119 filed 2 Feb. 2010 
     TECHNICAL FIELD 
     The present invention relates to arrangements and methods for a fire arm, and in particular to methods and arrangements for firing a fire arm. 
     BACKGROUND 
     A firearm is a device which projects either single or multiple projectiles at high velocity through a controlled explosion. The firing is achieved by gases produced through rapid, confined burning of a propellant. There are also firearms which use electromagnetic energy to project projectiles. 
     Firearms are often equipped with different types of sights used to give additional accuracy using a point of aim for the fire arm. The fire arm may for instance be equipped with a telescopic sight, commonly called a scope. Other sighting systems are iron sights and laser sights. 
     When shooting with a fire arm the accuracy is affected from among others the stance of the shooter. Other factors that affect the accuracy of the fire arm are how the shooter is breathing, aiming and fires the fire arm. Yet other factors that affect the accuracy of the fire arm are for instance if the shooter is shaking or swaying. The accuracy is also affected from how the shooter controls the trigger. A greater accuracy is achieved if the shooter steady presses the trigger instead of slaps the trigger. 
     There are thus several problems in achieving accuracy when shooting with a firearm. 
     One solution to achieve greater accuracy when shooting with a fire arm is a system known as BORS which has been developed by the Barrett Firearms Company. The BORS module is in an electronic Bullet Drop Compensation (BDC) sensor/calculator package intended for long-range sniping. To establish the appropriate elevation for the fire arm the shooter enters the ammunition type into the BORS and the range to the target. The system automatically determines air density, as well as cant or tilt in the fire arm itself. These environmental factors are incorporates into the elevation calculations for the fire arm. 
     Even though the BORS system is proved useful the system does not compensate for shakings and/or sways from the shooter. 
     There is therefore a need for an improved solution for increasing the accuracy when shooting with a fire arm, which solution solves or at least mitigates at least one of the above mentioned problems. 
     SUMMARY 
     An object of the present invention is thus to provide arrangements and methods that increase the accuracy when shooting with a fire arm. 
     This object is according to the present invention achieved by providing the fire arm with determining means for determining a movement of an aim point for the fire arm relative to a target. The fire arm also comprises processing means configured to determine a target point for the aim point based on the movement of the aim point and to predict the future movement of the aim point. Firing mean in the fire arm use the target point and the predicted movement of the aim point to fire the fire arm when the aim point is predicted to be within a tolerance of the target point. 
     According to a first aspect the present invention relates an arrangement for firing a fire arm. The arrangement comprises determining means for determining a movement of an aim point for the fire arm relative to a target. Processing means in the arrangement are configured to determining a target point for the aim point based on the movement of the aim point and to predict a future movement of the aim point based on the movement of the aim point. The arrangement further comprises firing means configured to fire the fire arm when the aim point is predicted to be within a tolerance of the target point. 
     According to a second aspect the present invention relates a method in a fire arm for firing the fire arm. The method comprises the steps of: determining a movement of an aim point for the fire arm relative to a target; determining a target point for the aim point based on said movement of said aim point; predicting a future movement of the aim point based on the movement of the aim point; and firing the fire arm when the aim point is predicted to be within a tolerance of the target point. 
     An advantage with embodiments of the present invention is that the arrangement compensates for shakings and/or sways from for instance the shooter or a weapon platform. Thereby the arrangement among others increase the accuracy of the fire arm 
     Yet another advantage of embodiments of the present invention is that the arrangement as a whole or in part can be mounted on an existing fire arm. It is therefore possible to apply the arrangement to a fire arm without modifying the fire arm. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will in the following be described in more detail with reference to enclosed drawings, wherein: 
         FIG. 1   a  illustrates schematically a fire arm according to prior art 
         FIG. 1  illustrates schematically an arrangement for firing a fire arm according to an exemplary embodiment of the invention 
         FIG. 2  illustrates a method according to an exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular sequences of steps, and device configurations in order to provide a thorough understanding of the present invention. It will be apparent to one skilled in the art that the present invention may be carried out in other embodiments that depart from these specific details. 
     Moreover, those skilled in the art will appreciate that functions and means explained herein below may be implemented using software functioning in conjunction with a programmed microprocessor or general purpose computer, and/or using an application specific integrated circuit (ASIC). 
       FIG. 1   a  illustrates a fire arm  200  according to prior art. The fire arm  200  comprises a laser sight  201  that will project an aim point  202  on a target  203 . If the shooter of the fire arm  200  for instance is shaking or swaying the aim point  202  will move on the target  203 . Since this aim point  202  is moving it hard for the shooter to know when to press a trigger  204  in order to fire a shot (not shown). The accuracy when shooting with the fire arm  200  will therefore reduce as a consequence of the shakings and/or sways from the shooter. 
       FIG. 1  shows an arrangement  5  for firing a fire arm  20  according to an exemplary embodiment of the present invention. Reference number  22  denotes the aim point  22  of the fire arm  20  at the target  50 . If the shooter of the fire arm  20  for instance is shaking or swaying the aim point  22  will move on the target  50 . The shaking and/or swaying may for instance arise from the shooters heart beats or breathing. 
     In this exemplary embodiment of the arrangement  5  according to the present invention the arrangement comprises a switch  65 . The switch  65  is connected to a processing means  60 , which will be described further down. The switch may in an exemplary embodiment of the arrangement  5  according to the present invention be mounted on a trigger (not shown) of the fire arm  20 . 
     In order to determine the movement of the aim point  22  relative to the target  50 , the arrangement  5  according to the present invention further comprises determining means  10  for determining a movement of the aim point  22  relative to the target  50 . When the switch  65  is pressed by a shooter (not shown), the determining means  10  starts to determine the movement of the aim point  22  relative to the target  50 . In another exemplary embodiment of the arrangement  5  the determining means  10  continuously determines the movement of the aim point  22  relative to the target  50 . 
     In an exemplary embodiment of the arrangement  5  according to the present invention the determining means  10  for determining the movement of the aim point  22  comprises a camera  80  which captures consecutive images of the target  50 . In this exemplary embodiment the determining means  10  are further configured to determining the movement of the aim point  22  by using image processing of the consecutive images from the camera  80 . The determining means  10  may for instance determine a target area  23  on the target  50 . The target area  23  on the target  50  may for instance be determined using thresholding which is a well known method of image segmentation. When using thresholding the target area  23  around the aim point  22  is found by marking individual pixels around the aim point  22  as “object” pixels if their value is greater than some threshold value (assuming an object to be brighter than the background) and as “background” pixels otherwise. 
     Thresholding is well known image processing method and will not further be described herein. Another method that may be used to find the target area  23  around the aim point  22  is to identify significant properties of the target near the aim point  22 . These significant properties may for instance be sharp gradients near the aim point  22 . Yet another method that can be used by the determination means  10  to identify the target area  23  around the aim point  22  is matching of intensities in subareas in the consecutive images around the aim point  22 . 
     When the determination means  10  has determined the target area  23  the determination means  10  can determine the movement of the aim point  22  relative to the target area  23  as a result from for instance shakings and/or sways from the shooter. The movement of the aim point  22  relative to the target  50  may be determined in many different ways. Positions of the aim point  22  relative to the target area  23  may for instance be extracted from consecutive images taken at equal intervals. These positions will then represent the movement of the aim point  23  relative to the target. 
     The camera  80  may in an exemplary embodiment of the arrangement  5  according to the present invention be incorporated in a telescopic sight (not shown) of the fire arm  20 . In yet another exemplary embodiment of the arrangement  5  according to the present invention the camera  80  is attached to a telescopic sight of the fire arm  20 . The camera  80  may also in another exemplary embodiment of the arrangement  5  according to the present invention be mounted directly on the fire arm  20 . In a further exemplary embodiment of the arrangement  5  according to the present invention a digital sight may be used. In this exemplary embodiment the consecutive images can be taken directly from the digital sight. 
     In another exemplary embodiment of the arrangement  5  according to the present invention the determining means  10  for determining a movement of the aim point  22  relative to the target  50  comprises at least one accelerometer  81 . In another exemplary embodiment of the arrangement  5  according to the present invention may the determining means  10  instead of an accelerometer  81  comprise an inertia sensor  81 . In this exemplary embodiment the determining means  10  are further configured for determining the movement of the aim point  22  by using signals from the at least one accelerometer or inertia sensor  81 . Using at least one accelerometer or inertia sensor  81  for determining the movement of the aim point  22 , relative to the target  50 , is only applicable when shooting at a target that is not moving. 
     The processing means  60  is further configured to determining a target point  21  for the aim point  22  based on the movement of the aim point  22 . The target point  21  may be determined in many different ways from the movement of the aim point  22  relative to the target  50 . If for instance the aim point  22  is moving back and forth relative to the target  50 , the target point  21  may be determined to a middle point (not shown) of the back and forth movement, because this is the point that the shooter probably aims at. 
     The processing means  60  is further configured to predict a future movement of the aim point  22  based on the movement of the aim point  22 . The future movement of the aim point  22  may be predicted in many different ways. In an exemplary embodiment of the arrangement  5  according to the present invention the processing means  60  is configured to predict a future movement of the aim point  22  based on a dynamic model of the fire arm  20 . The dynamic model of the fire arm  20  may take many different factors into account related to the fire arm  20 , like for instance the weight and size of the shooter or the weapon platform (not shown) the fire arm rests on, and inertia for the fire arm  20 . 
     The dynamic model of the fire arm  20  may be a self improving dynamic model, i.e. the model is adaptive and is continuously improved by feedback from the actual aim point motion, observed from the camera images. 
     In another exemplary embodiment of the arrangement  5  according to the present invention the processing means  60  is further configured to wait until a movement of the target point  21  is within a tolerance before starting to predict the future movement of the aim point  22  based on the movement of the aim point  22 . 
     The arrangement  5  according to the present invention further comprises firing means  70  configured to fire the fire arm  20  when the aim point  22  is predicted to be within a tolerance of the target point  21 . Since the firing means  70  fires the fire arm when the aim point  22  is predicted to be within a tolerance of the target point  21  the accuracy of the fire arm  20  is greatly improved. 
     In exemplary embodiments of the arrangement  5  according to the present invention, if the switch  65  is released before the firing means  70  has fired the fire arm  20 , the firing means  70  will not fire the fire arm  20 . 
     In other exemplary embodiments of the arrangement  5  according to the present invention the switch  65  may be a switch with several positions (not shown). In a configuration of this exemplary embodiment according to the present invention, the shooter can fire the fire arm  20  by fully pressing the switch  65 . 
     The firing means  70  may in an exemplary embodiment of the arrangement  5  according to the present invention be mounted on a trigger (not shown) of the fire arm  20 . In another exemplary embodiment of the arrangement  5  may the firing means be an integrated part of the fire arm  20 . 
     In an exemplary embodiment of the arrangement  5  according to the present invention may the arrangement  5  be configured for detachable connection to the fire arm  20 . 
     The fire arm  20  that is used in the above exemplary embodiments of the arrangement  5  according to the present invention may be a fire arm that is hand held. The fire arm  20  may also be a larger fire arm that resides on for instance a vehicle or a weapon platform. 
     It should be noted that arrangement depicted in  FIG. 1  may comprise other elements or means not illustrated. Furthermore, the different blocks of the arrangement  5  are not necessarily separated but could be included in a single block. 
     Referring to  FIG. 2 , there is illustrated a flowchart of a method describing the steps in a fire arm  20  for firing the fire arm  20  in accordance with previously described embodiments of the present invention. As shown in  FIG. 2 , the method comprises the steps of: 
     Step  220 : determining a movement of an aim point  22  for the fire arm  20  relative to a target  50 . 
     Step  230 : determining a target point  21  for the aim point  22  based on the movement of the aim point  22 ; 
     Step  240 : predicting a future movement of the aim point  22  based on the movement of the aim point  22 ; 
     Step  250 : firing the fire arm  20  when the aim point  22  is predicted to be within a tolerance of the target point  21 . 
     While the present invention has been described with respect to particular embodiments (including certain device arrangements and certain orders of steps within various methods), those skilled in the art will recognize that the present invention is not limited to the specific embodiments described and illustrated herein. Therefore, it is to be understood that this disclosure is only illustrative. Accordingly, it is intended that the invention be limited only by the scope of the claims appended hereto.