Target shooting apparatus

Abstract

 A method and apparatus to provide a weapon operator with information to facilitate correctly adjusting the sights on a weapon.
A hit position detector (18, 22) determines where projectiles fired from a weapon pass through a vertical plane in relation to the aiming point. The hit position information is recorded and is utilised in computing (22) the mean point of impact for the group of shots and also in computing the distance from the mean point of impact to the centre of the aiming point. A display (28) indicates either the mean point in terms of distance or may indicate the number of clicks or degrees that the weapon sighting system must be adjusted in order to place the mean point of impact on the aiming point.
One embodient determines the validity of a shot group by comparing the smallest circle which will encompass the group of shots and a predetermined circle size and displaying an indication of the validity or validity of the shot group.

Description

[0001] THE PRESENT INVENTION relates to target shooting apparatus, and more particularly to apparatus for use when adjusting the sighting mechanisms associated with projectile firing weapons and specifically to a method for the semi-automatic zeroing of a weapon sight, and the invention also relates to apparatus for use when training marksmen in the use of projectile firing weapons and specifically to a method and apparatus for shot grouping firing exercises associated with direct fire projectile firing weapons.

[0002] "Zeroing" is a term for a procedure carried out on a weapon in order that projectiles fired from the weapon strike an aiming point at a predetermined distance from the sights of the weapon. The weapon whose sights are to be adjusted could be anything from small arms to large calibre tank armament or larger weapon systems. ,

[0003] Closely related to zeroing is the concept of shot group firing exercises with a weapon. "Shot Grouping" is a term for a procedure carried out during the firing of a weapon in order to determine the spread of a group of projectiles fired from the weapon striking an aiming point at a predetermined distance from the muzzle of the weapon. As with zeroing, the weapon could be anything from small arms to large caliber tank armament or larger weapon systems.

[0004] Shot group firing exercises of small arms requires that two or more shots be fired at an aiming point target under conditions of no wind and for a given weapon and ammunition type (caliber and. muzzle velocity), and that the extreme spread of all the projectiles within a given group at a specified distance, generally between 25 to 300 metres, be no larger than an accepted standard.

[0005] Zeroing military-type small arms requires that the weapon sights be adjusted so that under conditions of no wind and for a given ammunition type (calibre and muzzle velocity), the point of impact of the projectile is precisely the same as the point of aim at a specified distance, generally about 250-300 metres. Adjusting a weapon to achieve the above consistency between point of impact and point of aim is complicated by two factors. First, because of variations in the weight of each round, the charge of powder used in each round and variations in the friction between the round and the weapon barrel, variations occur in the muzzle velocity and thus in the trajectory of each round fired. Thus, if a number of rounds are fired from a weapon which is rigidly clamped with a fixed aiming point, the rounds will impact in a group rather than at a single spot. The group size can be characterised by the diameter of a circle which can encompass all of the impacts of the given group. The standard U.S. Army issue M-16 rifle series loaded with standard issue rounds will exhibit a group size of about 4 inches (10 cms) in diameter at a target distance of 100 metres. Thus, the fact that a projectile strikes some centimetres from the centre of the aiming point does not necessarily indicate that the weapon sights have been improperly adjusted.

[0006] Second, even though a weapon may have the capability of firing a 4- inch diameter shot group at 100 metres, human factors and the skill applied when firing can cause the size of the shot group to vary considerably. Therefore, the correct application of the basic rifle marksmanship fundamentals are critical in consistently achieving a shot group that is acceptable in order to permit the weapon operator to continue on with his marksmanship zeroing training. The U.S. Army currently utilizes a 4-centimeter diameter shot group size at 25 metres as an acceptable standard and 16 centimeters diameter shot group at 100 metres.

[0007] In addition, even though it is desirable to have a weapon system zeroed at the "zero" distance (about 250-300 metres in the small arms example), it will be seen that the traditional method of zeroing a weapon is not practical at this distance. In the traditional method, the weapon's operator fires several rounds at a paper target and then walks to inspect the target to determine the distance the rounds are from the centre of the aiming point. The operator then returns to the firing point, adjusts the sights of the weapon and repeats the process until he is satisfied that the sights are correctly adjusted. This walking back and forth would consume an inordinate amount of time if the target were located at 100 metres from the firing point, let alone the 200-300 metre desired zeroing distance. Therefore, targets for zeroing purposes are normally placed at a much closer distance, usually 25 metres (in acordance with U.S. Army practices), and a predetermined vertical offset is then allowed between the point of impact and the point of aim in order to zero the weapon at the desired 250-300 metres.

[0008] Formalized zeroing procedures are presently in existence for most major military services with the U.S. Army system being typical. In the U.S. Army system a paper target is supported at a distance of 25 metres or more from the firing point. The weapon's operator fires three shots (shot group) at the target and then moves forward to examine closely the group of holes in the target. If the holes are too widely spread (if the smallest circle which will encompass all shots is larger than the required group circle size), the operator goes back and fires three additional shots at the target after having covered or marked the initial holes in the target so as to avoid confusion between the various groups of holes. If the exercise involves shot group firing, the weapon's operator and/or a trainer will analyze the group and determine if the spread of shots is too wide before covering the group of holes. Once the analysis has been made, the initial bullet holes are covered or marked in such a way so as to avoid confusion between various groups and the weapon's operator fires a second and third group, repeating the entire process until all the shots of a shot group impact within the desired grouping/zero circle on the target.

[0009] For grouping exercises, if two or more groups are fired that fit within the desired size grouping circle, it is expected that the operator is capable of placing all future groups of two or more shots within an acceptable size grouping circle. He will therefore be permitted to continue on to the next phase of weapon zeroing training.

[0010] For zeroing purposes, if the holes do lie within the acceptable size grouping circle, a second group of three shots is fired without any change in the weapon sights or firing position.

[0011] If the holes are within the "valid" circle, a determination is made as to whether the shots lie inside the zero circle which is approximately 1 1/2 inches (4 cms) in diameter (at 25 metres) centered on the aiming point of the paper target. If the holes do lie within the zero circle, a second group of three shots is fired without any change in the weapon sights to confirm that the weapon is correctly zeroed. If all three shots are not within the zero circle, the weapon's operator must estimate the average shot position, i.e., the mean point of impact (MPI) for the shot group and then estimate or measure the vertical and horizontal distances from this point to the centre of the aiming point. These measurements then must be converted to sight corrections which are made in the weapon sighting system, and the whole process is then repeated until all the shots of a shot group impact within the required zero circle on the target.

[0012] The weapon is considered correctly adjusted only -if the operator is able to place all rounds in two successive three-shot groups within the zero circle. There are variations among the military services as to these procedures such as the number of rounds fired in each group, but the process is basically the same and relies heavily upon the operator's skill in determining the existence of a valid or invalid group, the mean point of impact for a group, the distance from the mean point of impact to the aiming point and the required corrective action to be taken with regard to sight adjustment in order to result in a correctly zeroed weapon. If the skill of the weapon's operator is deficient in any one of these four areas, it will be difficult, if not impossible, to achieve a correctly zeroed weapon.

[0013] It is an object of the present invention to eliminate the necessity for a physical inspection of the target for a shot or shot group position determination.

[0014] According to one aspect of this invention there is provided an apparatus for automatically aiding an operator in setting sights on a weapon, which is capable of firing a plurality of projectiles at an aiming point, said apparatus comprising: hit position detection means for determining where a projectile fired from said weapon passes through a vertical plane, said plane including said aiming point and further being generally perpendicular to a line connecting said aiming point and said weapon; means, responsive to said detection means, for recording the hit position of at least two projectiles; means, responsive to said recording means, for computing the mean point of impact (MPI) of said projectiles and for computing the distance from said MPI to said aiming point; and means, responsive to said computing means for indicating to said operator said distance, or information determined from said distance.

[0015] Preferably said recording means record the position of at least three projectiles and preferably said indicating means calculates and provides sight correction information to said operator to aid in minimizing said distance during subsequent firings.

[0016] Advantageously said apparatus includes means for computing the smallest circle which will encompass the hit positions of said projectiles, for comparing said circle with a predetermined circle size and for providing an output indicating that said hit positions comprise a valid or invalid group, said valid or invalid group being determined by whether the computed circle is smaller than or larger than said predetermined circle, respectively, and preferably said indicating means comprises a display means which is responsive to said circle computing means, for visually indicating the validity or invalidity of the group to the weapon's operator.

[0017] Conveniently said apparatus further includes means preprogrammed with information on said weapon sights and responsive to said MPI computing means, for indicating to said operator the adjustments required on the weapon sights so as to place the MPI directly on the aiming point.

[0018] According to another aspect of this invention there is provided a method for adjusting the sights on a weapon so that a means point of impact (MPI) is centered on an aiming point of a target comprising: firing a group of shots from a weapon at a position detector having an aiming point so that projectiles fired from said weapon pass through a vertical plane spaced from said target; recording hit position information from the detector; and utilizing said information for determining the MPI for said group of shots and for determining any deviation the MPI from the aiming point and indicating said MPI deviation, or information determined from said deviation, to the weapon operator; whereby the weapon operator may correctly adjust the sights on said weapon so that the MPI is centered on said aiming point.

[0019] Preferably said weapon has a sighting system and the step of indicating further includes indicating the adjustment that must be effected to said sighting system for placing the MPI on the aiming point.

[0020] Conveniently said sighting system has click stops and the step of indicating further includes specifying the number of click stops by which said sighting system must be adjsuted.

[0021] Advantageously said step of indicating further includes the step of displaying the MPI.

[0022] Preferably the method includes the step of determining the validity of said group of shots by comparing a predetermined circle with a circle corresponding to the smallest circle which will encompass said group of shots, and may further include the step of displaying an indication of validity or invalidity for said group shots.

[0023] It will be appreciated that in one embodiment of this invention a hit position detector is combined with a recorder such that at least a temporary record is made of the hit position of each shot. A computer processor, based on the recorded hit positions, computes the group size and displays on a video display unit the validity or invalidity of the group based thereon. If a valid group is determined, the mean point of impact of the shot group, the distance from the mean point of impact to the aiming point and the required sight corrections necessary, if any, are displayed on a video display unit to the operator. In a preferred embodiment, if six groups of shots are fired and do not result in two consecutive zero groups, the operator is visually instructed to seek remedial help. In a further preferred embodiment if three consecutive invalid groups are fired, the weapon's operator is visually instructed to seek remedial help terminating the zeroing program.

[0024] In a further embodiment, instead of using the mean point of impact and its distance from the aiming point as the sight correction criteria, sight corrections are based upon the average of all shots fired in the current zeroing program with only shots from invalid groups beings excluded therefrom. As each sight correction is displayed, the computing system shifts to the recorded positions of all shots by an amount equal to the expected effect of the sight correction such that when the next mean point of impact is computed, all of the mean points of impact will have positions as if they had been fired with the most recent sight corrections. This permits a rapid damping of even minor random variations in the mean point of impact for even a fixed aiming point weapon.

[0025] According to a further aspect of this invention there is provided an apparatus for automatically aiding in conducting shot group firing practices with a weapon, said weapon being capable of firing a plurality of projectiles at an aiming point, said apparatus comprising: hit position detection means for determining where a projectile fired from said weapon passes through a vertical plane having a predetermined relationship with said aiming point and further being generally perpendicular to a line connecting said aiming point and said weapon; means, responsive to said detection means for recording the hit positions of at least two projectiles which constitute a shot group; means, responsive to said recording means for determining from said hit positions the size of the shot group; and means, responsive to said computing means, for displaying said size.

[0026] Preferably at least three projectiles are fited and further wherein said computing means and displaying means respectively calculates and displays the hit position of each shot of the shot group after said three projectiles are fired.

[0027] Conveniently said means for determining the size of the shot group further determines the mean point of impact (MPI) of the shot group and the display means indicates said MPI.

[0028] Advantageously said determining means includes means for computing the smallest circle which will encompass said projectile hit positions, for comparing said circle with a predetermined circle size and for providing an output indicating whether said hit positions comprise a valid or invalid shot group, said valid or invalid shot group being determined by whether the computed circle is smaller than or larger than said predetermined circle, respectively, and wherein said indicating means comprises a display means which is responsive to said circle computing means for visually indicating the validity or invalidity of the shot group.

[0029] According to a further aspect of this invention there is provided a method of conducting shot group firing practices whereby a group of shots is fired so that the shots are grouped within a circle of predetermined diameter comprising: firing a group of shots at a hit position detector having an aiming point whereby said shots pass through a vertical plane spaced from said target; recording hit position information from each shot detected by said detector; determining the smallest circle which will encompass the hit positions detected for each shot group; indicating whether said circle is larger or smaller than a predetermined circle size.

[0030] Preferably the step of indicating further comprises indicating a valid group when said circle size is less than said predetermined size and indicting an invalid group when said circle size is greater than the predetermined size.

[0031] The method may include displaying the hit positions for each shot of a group after displaying all the shots at the group have been fired. The method may also include the step of automatically progressing to a semi-automatic rifle zeroing exercise when a first predetermined number of groups of shots are determined to be valid. Also the method may include the step of automatically stopping the grouping exercise when a second predetermined number of groups of shots are determined to be invalid.

[0032] A group may comprise three shots, the first predetermined number may be two, and the second predetermined number may be six.

[0033] The invention will now be described by way of example with reference to the accompanying drawings, in which:

FIGURE 1 is a perspective view showing a target range incorporating one embodiment of the present invention;

FIGURE 2 is a perspective view of a target, target mechanism, hit, hit position, and ricochet detection devices utilized with an embodiment of the present invention;

FIGURE 3 is a front view of an aiming point suitable for use in the described embodiment of the present invention;

FIGURES 4A to 4C are a representation of a video display unit displaying information determined in accordance with the shot grouping aspects of the present invention;

FIGURES 5A and 5B are representations of a video display unit displaying information determined with an apparatus in accordance with the present invention;

FIGURES 6A and 6B are a logic flow diagram of one embodiment of the present invention; and

FIGURES 7A and 7B are a logic flow diagram of a grouping embodiment of the present invention.

[0034] Referring now more particularly to the drawings, wherein like numerals represent like elements throughout the several views, Figure 1 shows in perspective view a marksmanship training range employing the present invention. The range has a pluraltiy of firing points 10 from whch marksmen 12 shoot at targets 13 and 14. It can be seen that the left-hand marksman in Figure 1 is shooting at an aiming point target 13 while the right-hand marksman is aiming at a more conventional target 14 which is in the "down" position.

[0035] Located in front of the targets 13 and 14 is, in one embodiment, an earthen embankment which does not obstruct the marksmen's view of the targets from the firing points but which permits the positioning of transducer arrays just below the lower edge of the target and out of the line of fire. The transducer arrays are connected by suitable cables 20 to the computer 22 situated in a control room 24 located behind the firing points. Alternatively, the transducers may be connected to a microprocessor or other data processing mechanisms located near the transducer array and then be coupled directly to the visual display units. Visual display units 28 provide an indication of hit position to the marksmen. A similar indication of the hit position is available in the control room by means of display unit 26 and also at a convenient outside location by means of display 30, which can be viewed by spectators 32. It can be seen that if it is desirable, the computer may be connected to a suitable printer or paper punch or other permanent recording device 34 to provide a permanent record of the marksmen's zeroing effort.

[0036] A more detailed disclosure of the operation of the transducer array 18 is set forth in U.S.A. Patent No. 4,307,292, said disclosure herein incorporated by reference. Suffice it to say that each transducer array detects the pressure wave generated by the projectile, such as a bullet, which is fired at the respective target. The computer 22 is operative to determine the hit position of the projectile as it passes through a measurement plane which is generally in front of and parallel to the target itself. This hit position information is then stored in the computer for further use as will hereinafter be discussed.

[0037] Figure 2 shows an aiming point target 13 mounted on a conventional "up/down" target mounting device in combination with the previously mentioned transducer array. A bullet has hit target 13 by travelling along trajectory 44. Pressure waves generated by the bullet's passage through air expand outward from the bullet's trajectory as shown by expanding rings 42 which impinge upon transducer array S-1, S-2, S-3, and S-4. Additionally, the impact of the bullet hitting aiming point target 13 may create acoustic vibrations 46 in the target member which are detected by hit detector 38. Thus, not only can the hit position be detected by such an array, but also the existence of a hit can be confirmed by the hit detector if necessary.

[0038] For situations in which hit detection is unnecessary (as in a preferred embodiment of the present invention) a paper target suitably mounted will provide a cheap and inexpensive aiming point to be used for zeroing a weapon at 100 metres. Turning to Figure 3, which shows such a target the centre spot, 51, is 5 centimetres in diameter with the external dimensions of the square, 55, being 400 centimetres on a side. A wooden frame 50 is secured to a vertical support 52 by conventional fastening means 53. The frame has, in a preferred embodiment, a centre square cutout as this is the region that a majority of bullets will pass and would be destroyed rather quickly in any event. Paper or a thin plastic foam sheet or other suitable material is laid over frame 50 and imprinted with a suitable design such as aiming mark 54, which will attract the eye of the weapon operator. In this manner, the aiming point will remain visible to the marksman even after a large number of hits have taken place in the vicinity of the aiming point.

[0039] Figures 4A to 4C illustrate the typical VDU displays and printout information presented to the marksman and trainer during grouping exercises. Turning first to Figure 4A, in the centre portion of a screen 40, is a representation of an aiming point 42 of a target 44 and a representation of where shots 1, 2 and 3 respectively have struck the target. Although each individual shot position can be displayed instantaneously, in a preferred embodiment where the group size is three shots, no hit position information is displayed until all three shots have been fired. This prevents the marksman from inadvertently trying to correct a poorly sighted rifle, change his aiming point and/or change his firing grip or firing position. With no feedback information until all shots in a group have been fired, consistently small groups should be obtained if the same aiming point is used, the weapon is in proper operating condition, and the marksman is correctly applying basic marksmanship fundamentals of weapon grip, sighting and aiming, breathing, trigger squeeze and follow-through. A scale may also be provided correlating the number of turns of a sight adjustment with a distance on the screen. Adjustment of the sight should result in shifting the shot group.

[0040] Preferably, at the right-hand portion of the screen, the system provides a shot grbup number and the actual size of the shot group (in centimeters or inches). Preferably, at the bottom right of the screen, an indication of whether the shot group was valid or invalid appears. On the displays indicated in Figures 4A-C, two were "valid" and one was "invalid" according to the grouping standards described hereinabove. When a group size is too large, the system provides an "invalid" indication 49. In addition, a centre display 47 of "Group too Large" may also appear at the bottom centre of the screen display informing the firer that the group spread was larger than the acceptable standard. After two valid groups are fired, a "Proceed to Zeroing" instruction 47' may be caused to appear at the bottom centre of the screen display (Figure 4C). This informs the marksman that he or she should be able to consistently fire a tight or valid shot group and should therefore be able to zero the rifle in the minimum number of rounds. On the other hand, if three consecutive invalid shot grups are fired, the indication "Remedial" may be caused to appear at the bottom centre of the screen display to inform the marksman and trainer that the marksman cannot fire a satisfactory shot group and should not be permitted to fire again until non-firing remedial basic rifle marksmanship fundamentals are practiced. In this way, ammunition and training time are not wasted by an individual who cannot consistently group shots.

[0041] Moreover, the grouping displays of Figures 4A to 4C may provide additional graphic information such as the x and y shot position coordinates for each shot, the terminal velocity of each shot fired, and the mean point of impact (MPI) for all three shots fired. When used in accordance with the present invention, the apparatus such as that disclosed in U.S. Patent No. 4,307,292 is operable to provide the necessary information for the display. The x-y shot position coordinates and the terminal velocity information may be used to check and/or verify the accuracy of the ammunition lot and ballistic accuracy of the weapon being fired.

[0042] To summarize, in utilising a preferred embodiment of the invention, the marksman is required to place all six shots of two groups (of three shots each) inside an acceptable size grouping circle. If the marksman fires three invalid or "too large" groups in succession, the grouping program terminates and the video display unit relays the message "Remedial" which is short for "remedial training required; check weapon". If 18 shots have been fired (six separate groups) without two successful shot groups being achieved, then the system will terminate with the "Remedial" message being displayed again.

[0043] As previously noted, the video display unit remains blank until all three shots of a group have been fired in order to prevent the marksman from instinctively or deliberately adjusting his point of aim or from otherwise changing or adjusting his marksmanship fundamentals during the firing of a group.

[0044] Obviously, different requirements could be set forth for qualification of a proper size shot group with more or less than a 16-centimetera diametre size group circle at 100 metres and more or less than three shots being used to constitute a group and more or less than two or more acceptable size shot groups constituting an acceptable standard for an individual to proceed to the weapon zeroing phase of training. Similarly, more or less than three "excess" or invalid groups in succession could be utilized or more or less than six groups without "proceed to zero" condition being achieved could be utilized to terminate the prgram and display any desired informational message.

[0045] Either after the marksman has been instructed to proceed to zeroing or in certainc ases directly, the marksman may then use the system for the semi-automatic zeroing of his or her weapon.

[0046] Figures 5A and 5B illustrate typical VDU displays and the information presented to the marksman thereon. Turning first to Figure 5A, on the left-hand portion of the screen, there is a representation of the aiming point of the target and a representation of where shots have struck the target in relation thereto. Although each individual shot position could be displayed, in a preferred embodiment, where the group size is three shots, no hit position information is displayed until all three shots have been fired. This prevents the marksmen from inadvertently trying to correct a poorly sighted rifle by changing his aiming point. With no feedback information until all shots in a group have been fired, consistently small groups should be obtained if the same aiming point is used and the weapon is in proper operating condition. The legend at the bottom of the left-hand portion of the screen indicates that even though the actual target-to-marksman distance is 50 metres, the correct adjustment of the sights will zero the rifle at 300 metres and the slight difference in height of the bullet trajectory has been automatically taken into account. Also, a scale is provided correlating the number of turns of a sight adjustment with the distance on the screen, such a sight adjustment will shift the group.

[0047] On the right-hand portion of the screen, there is an indication that the zeroing program is in effect for a 7.62 millmeter self-loading rifle (SLR) small arms weapon. The group number and status of a group fired is provided as well as front and rear sight changes. As can be seen, group No. 1 was an invalid group and the indication "too large" was supplied. Because this was an invalid group, no sight correction is suggested and, hence, the legend "no change". Group No. 2 not only was a valid group but also the mean point of impact was determined to be within the zero circle and thus no sight change was necessary. However, in a preferred embodiment, it is necessary to have two "zero" groups consecutively in order to assume that the weapon has been properly zeroed. Therefore, the legend "confirm" is displayed indicating that a further confirmation group is required.

[0048] The third group, although "valid", has a mean point of impact slightly out of the zero circle and thus the sight change information of one click upward and half of a click to the left is displayed. At the bottom right portion of the display, it can be seen that the marksman is being prompted to fire shot number one in the fourth group, although the hit position of this shot and the rest in the group will not be displayed until all three shots of the group have been fired.

[0049] Shown in Figure 5B is another embodiment of a VDU display and the information presented to the marksman thereon. The left portion of the display illustrates the target 400 and contains a vertical scale sight adjustment scale 401 along the left vertical edge and a horizontal scale sight adjustment 402 along the lower horizontal edge. The display may illustrate one or more target silhouttes 403 superimposed on the zeroing target; for instance 175 and 250 metres. The display may further illustrate the zero circle 404 and a pattern 405 to indicate the aiming point. The information contained on the right side of the display is similar in most regards to the information described hereinabove with respect to Figure 4 with certain notable exceptions. The weapon being zeroed is an M16A1 rifle and the program for that rifle is in effect. Further, the display indicates that the third group of shots, although "valid" has a mean point of impact slightly out of the zero circle and thus the change of sight information of one click clockwise for the first sight and five clicks counterclockwise for the rear sight is displayed.

[0050] In a preferred embodiment of the invention, the following parameters are set forth in the computer program and can be briefly summarized as follows: The marksman is required to place all six shots of two successive groups (of three shots each) inside the zero circle. If the marksman fires three invalid or "too large" groups in succession, the zeroing program terminates and the video display unit relays the message "remedial" which is short for "remedial training required/check weapon". If 18 shots have been fired (six separate groups) without a successful zeroing being achieved, then again the program terminates with the "remedial" message being displayed. Consistent with conventional U.S. zeroing procedures, sight corrections are calculated from the mean point of impact of the last three shots fired only, as opposed to other systems which will be discussed hereinafter. As peviously noted, the video display unit remains blank until three shots of a group have been fired preventing the marksman from instinctively or deliberately adjusting his point of aim during the firing of a group. Sight corrections in "clicks" and the vertical offset between the point of aim and the mean point of impact are set up to be correct for the U.S. Army rifle type M16A1.

[0051] Obviously, different requirements could be set forth for qualification as a proper zero group with more or less than three shots being used to constitute a group and more or less than two successive "zero" groups constituting weapon zeroing. Similarly, more or less than three "excess" or invalid groups in succession could be utilised or more or less than six groups without a "zero" condition being achieved could be utilised to terminte the program and display any desired informational message. Any number of past shots could be averaged to determine a mean point of impact, for example, the last two groups, the last three groups, or all groups. Obviously, the sight corrections displayed on the video display must correspond to the weapon system being used and the present invention is believed appropriate for all projectile firing weapons systems from small arms such as the M16A1 to large calibre tank armament.

[0052] In a further embodiment of the present invention as alluded to with regard to Figure 5B, a United Kingdom, or "UK" zeroing mode may be selected in which sight corrections and the vertical offset between point of aim and correct mean point of impact are adjusted for the 7.62 SLR. Sight corrections, instead of using the average error of the preceding three shots (distance between mean point of impact and centre of aiming point), are based on the average of all shots fired so far in the current zeroing exercise with only shots from excess or invalid groups being excluded. Thus, as more groups are fired, the number of shots averaged increases thereby improving the quality and reducing the effect of the inevitable sight correction. However, as each sight correction is displayed, the computer program automatically shifts the recorded positions of all shots previously fired by an amount equal to the effect of the new correction so that, when the next average shot position is computed, all the shots averaged have positions as if they had all been fired with the latest sight settings.

[0053] As previously noted, the UK zeroing method takes into account the fact that successive groups of rounds fired, even from a completely fixed aiming point, will not have an identical mean point of impact. This effect is exaggerated as the number of rounds in a group is reduced and thus for very small round groups, even if the weapon is perfectly zeroed the mean point of impact will often indicate that some sight correction is required. The UK method eliminates the danger of "chasing your own tail" by increasing the effective size of the group as the zeroing procedure proceeds and thus the inherent "randomness" of the mean point of impact location decreases and very quickly becomes negligible.

[0054] Figures 6A and 6B are a logic flow diagram to implement one embodiment of the present invention. This logic flow diagram can be implemented in a variety of microprocessor based minicomputers by one of ordinary skill in the art. Upon initial start-up, the display is cleared of any pre-existing information and immediately displays a "prompt" requesting that the marksman fire shot No. 1. This continues until shot No. 1 is fired, at which point shot No. 2 and shot No. 3 are requested. The hit position of each shot is recorded as it occurs and after three shots have occurred, the computer assesses the group size and position. The group is classified as being invalid, valid or a zero group based upon the previously programmed group size (in a preferred embodiment 16 cm at a 100 metre distance). The group assessment is assigned a group number consecutively with invalid groups being queried as to whether they are the third consecutive invalid group. Obviously, a valid or a zero group would reset the counter as far as invalid groups are concerned. If the invalid group is not the third consecutive invalid group, the display indicates that the group is too large and that "no sight change" is required. If it is the third invalid group, then there is either a problem with the marksman's technique in obtaining valid shot groups or there may be a difficulty with the weapon being used (loose sights, faulty ammunition, etc.). Upon determining that this is the third invalid group, the visual display will indicate "remedial" and the zeroing program will terminate.

[0055] For a valid group determination, the logic flow first determines whether this is the sixth group in the current zeroing progam. If it is, the video display system indicates "remedial" and the program terminates. If it is not the sixth group, the display indicates the mean point of impact, displays the indication "valid" and also calculates and displays the desired sight corrections and returns to prompt the marksman for the next shot group. In the event the group is a "zero group", it is also queried as to whether it is the sixth group. If it is the sixth group, this is the maximum number of groups permitted during the zeroing program and the program will stop. However, if the preceding group was a zero group, this would be the second consecutive zero group and an indication that the weapon is properly zeroed. Thus, this query is made and if the answer is yes, the display indicates "zeroed" and the program terminates. If the preceding group was not a zero group, even though the present one is a zero group, the display will indicate "remedial" and the program will terminate.

[0056] Going back to the determination of whether this zero group was the sixth group, if it was not the sixth group, it still must be determined whether the preceding group was a zero group. If it was, then two consecutive zero groups have occurrred and the video display will indicate "zeroed" and the program will terminate. If the preceding group was not a zero group, the display will indicate that the present group is a "zero group", display the mean point of impact and also display "confirm" returning the marksman to the prompt system for the next shot group to confirm the zeroing of the weapon.

[0057] The present invention is fully operative on the hardware disclosed in the above-identified U.S.A. Patent No. 4,307,292. The conventional target disclosed therein is removed and replaced by a target and target support as set forth with reference to Figure 3, which may be comprised of 3/8 inch (1 cm) water-resistant plywood. The program utilised presumes that the automatic air temperature measuring circuit is included and operative in order to maintain the accuracy of hit position location information. The program constants are set up for a marksman-to-target distance of 100 metres, although different distances could easily be programmed into the computer. The computer itself in one embodiment is the LSI-2/20G minicomputer available from Computer Automation, Inc., of Irving, California, part No. 10560-16. The basic LSI-2/20G unit may be equipped with an additional memory board available from Computer Automation, part No. 11673-16, which expands the computer memory to allow for a larger "BASIC" program. The computer is also preferably equipped with a dual floppy disk drive available from Computer Automation, part No. 22566-22, and a floppy disk controller availabe from Computer Automation, part No. 14696-01. Computer 22 may include a suitable visual display unit 26 which includes a keyboard such as Model "CONSUL 520" available from Applied Digital Data Systems, Inc., at 100 Marcus Boulevard, Hauppauge, New York 11787. The CONSUL 520 is plug-compatible with the LSI-2/20G minicomputer. A graphics generator/visual display unit 28 may be in one embodiment, Model MRD "450" which is available from Applied Digital Data Systems, Inc. and is plug-compatible with the LSI-2/20G minicomputer.

[0058] The zeroing program is loaded into the LSI-2/20G computer on power-up by the normal means as set forth in the Manufacturer's Operating Manuals. A source listing of an exemplary program is included as Appendix 1, and the preparation of such a program will be readily obvious to one of ordinary skill in the art in view thereof. In Appendix 1, lines 1-48 are general program initializations which include setting the size of the zero circle, the dimensions of an invalid or "too large" group, the number of shots in the group, the mode selection such as "UK" or "U.S." zeroing, etc. Lines 3,000 to 3,480 are the basic control of the overall zeroing algorithm which then calls upon various sub-routines to perform the subsidiary functions such as prompting the firing of a three shot group, calculating mean point of impact, sight correction and displaying messages. Lines 1,000 to 1,350 are the basic three-shot group position calculation and are repeated three times to get the three shots fired. Once all three shots have been fired by the marksman, lines 1,355 to 1,380 cause the three shots to be displayed by calling up the display sub-routine which starts at line 47 and terminates at line 441.

[0059] Once the three shots are collected and displayed, program execution jumps to line 675. From 675 to 997 and from 1,490 to 1,585, the three shots are analyzed and data on the group type (invalid, valid, zero), the mean point of impact, and sight corrections are determined. Program execution is returned to the calling program with a variable "N7" indicating the type of shot (N7 = 0 for invalid group, 1 for valid group, 2 for zero group). Sight corrections based upon the previous three-shot average (US-mode) are calculated from lines 1,507 to 1,585 and for average of all shots (UK-mode) from line 1,600 to line 1,640. It should be noted that the adjustment of shot positions in lines 1,555 to 1,570 alter the sight correction calculations as previously noted with sight correction calculations as previously noted with respect to the UK-mode.

[0060] When the zeroing program is concluded, either by reaching a successful zeroing of the weapon, or by having three successive invalid groups, or by reaching six groups being fired, the program optionally will print out the information on a line printer which is implemented from lines 6,000 to 9,130 in the program.

[0061] This program listing is an exemplary program for performing the operations indicated by the flow diagram of Figures 6A and 6B and should not necessarily be construed to be associated with any particular hardware. As will be understood by the man skilled in the art, specific input and output formats as well as the input data required will depend to a large extent upon the hardware utilized.

[0062] Illustrated at Figures 7A and 7B is a flow diagram for performing a shot grouping program. As will be apparent to the man skilled in the art, the shot grouping flow chart is in many respects similar to the zeroing flow chart of Figures 6A and 6B but inasmuch as only the size of each group is crucial for the grouping exercises, many of the steps indicated on Figure 6B for zeroing are omitted in 7B from the grouping flow chart. Specifically, in Figure 7B, where a valid third group is obtained, the system will simply display "Proceed to Zero" and then await further instructions to commence the zeroing program. Where no valid shot group is obtained after three groups of three shots, the system will display REMEDIAL and shut down, thereby allowing the marksman to seek remedial help in marksmanship fundamentals. Of course, instead of zeroing instructions, the grouping programs display whether a shot group was valid or invalid (too large) and the group size. As mentioned above, shot coordinated and MPI can also be displayed. Moreover, each shot group will only be assessed for size and possibly position, not for whether it is zeroed.

[0063] Obviously, many modifications can be made to the present invention to meet the specific needs of the particular weapon being zeroed. Additionally, different hit position detection systems other than the system described in U.S.A. Patent No. 4,307,292 can also be used, although this system is believed to be the most accurate cost-effective system available to date. The important characteristic of a hit position system will be the accuracy of measurement and as long as an accuracy of 5 to 10 millimetres at a range of 100 metres is achievable, such a hit position detection system would be compatible with the present invention. Possible alternate systems would be shock wave sensing systems using positional/angular sensors (rods, bars, "U"-shaped sensors, etc.), cavity or box targets, microwave and laser hit position detection systems. Similarly, the display system utilised to display information to the marksman as described above is an extremely effective system. However, simplified displays based on liquid crystal and/or light emitting diodes could be utilised. In fact, it is anticipated that audible indication systems utilizing speech synthesis technology could provide the information to the marksman. The audible message might be "valid group--sight one click counterclockwise." Thus, the display system can be tailored to the specific mission needs of the service utilising the system.

[0064] From the foregoing it will be appreciated that the present invention may eliminate the requirement that a weapon's operator estimate and/or determine the validity of a single or multiple shot group, and also may eliminate the necessity for the weapon's operator to estimate and/or determine the mean point of impact of a shot group, or measure the distance of the mean point of impact of a shot group from the centre of he aiming point.

[0065] It will be appreciated that the present invention may eliminate the necessity for the weapon's operator to determine required sight corrections based on the distance of the mean point of impact of a shot group from the aiming point. Also the present invention may provide a mechanism whereby zeroing of a weapon is automatically monitored such that an excessive number of rounds are not fired in an attempt to obtain zeroing on a faulty weapon (a weapon with a faulty barrel or a weapon in which the sights may be loose, bent or inconsistent) or by a weapon's operator who is incapable of consistent firing of the weapon.

[0066] The preferred embodiment of the present invention provides a semi-automatic display sequence which instructs the weapon's operator when to fire the required rounds to comprise a group, indicate the hit position of each round fired, determine whether the rounds fired in a group constitute a "valid" group, compute and display the mean point of impact of the group, compute and display the distance from the mean point of impact to the centre of the aiming point and display any required sight corrections to the operator without requiring the weapon's operator to leave the firing station.

[0067] Also it will be appreciated that the preferred embodiment of the invention provides a mechanism whereby the location of each shot is displayed on a firing point video display unit and determining the size of the shot groups of a weapon is automatically monitored such that an excessive number of rounds are not fired in an attempt to obtain an acceptable shot group size with a faulty weapon (a weapon with a faulty barrel or a weapon in which the sights may be loose, bent or inconsistent) or by a weapon operator who is incapable of consistently firing an acceptable shot group size.

[0068] The preferred embodiment also permits the elimination of the necessity for the weapon operator or trainer to estimate and/or determine the mean point of impact of a shot group.

Claims

1. An apparatus for automatically aiding an operator in setting sights on a weapon which is capable of firing a plurality of projectiles at an aiming point, said apparatus comprising: hit position detection means for determining where a projectile fired from said weapon passes through a vertical plane, said plane including said aiming point and further being generally perpendicular to a line connecting said aiming point and said weapon; means, responsive to said detection means, for recording the hit position of at leat two projectiles; means, responsive to said recording means, for computing the mean point of impact (MPI) of said projectiles and for computing the distance from said MPI to said aiming point; and means, responsive to said computing means for indicating to said operator said distance, or information determined from said distance.

2. An apparatus according to claim 1, wherein said recording means record the positions of at least three projectiles and further wherein said indicating means calculates and provides sight correction information to said operator to aid in minimizing said distance during subsequent firings.

3. An apparatus according to claim 1 or 2 wherein said apparatus includes means for computing the smallest circle which will encompass the hit positions of said projectiles, for comparing said circle with a predetermined circle size and for providing an output indicating that said hit positions comprise a valid or invalid group, said valid or invalid group being determined by whether the computed circle is smaller than or larger than said predetermined circle, respectively, and wherein said indicating means comprises a display means which is responsive to said circle computing means, for visually indicating the validity or invalidity of the group to the weapon's operator.

4. An apparatus according to any one of claims 1 to 3, wherein said apparatus further includes means preprogrammed with information on said weapon sights and responsive to said MPI computing means for indicating to said operator the adjustments required on the weapon sights so as to place the MPI directly on the aiming point.

5. A method for adjusting the sights on a weapon so that a mean point of impact (MPI) is centred on an aiming point of a target comprising: firing a group of shots from a weapon at a position detector having an aiming point so that projectiles from said weapon pass through a vertical plane spaced from said target; recording hit position information from the detector; and utilizing said information for determining the MPI for said group of shots and for determining any deviation of the MPI from the aiming point and indicating said MPI deviation, or information determined from said deviation, to the weapon operator; whereby the weapon operator may correctly adjust the sights on said weapon so that the MPI is centred on said aiming point.

6. A method according to claim 5, wherein said weapon has a sighting system and the step of indicating further includes indicating the adjustment that must be effected to said sighting system for placing the MPI on the aiming point.

7. A method according to claim 6, wherein said sighting system has click stops and the step of indicating further includes specifying the number of click stops by which said sighting system must be adjusted.

8. A method according to claim 5, or 6 or 7, wherein said step of indicating further includes the step of displaying the MPI.

9. A method according to any one of claims 5 to 7 further including the step of determining the validity of said group of shots by comparing a predetermined circle with a circle corresponding to the smallest circle which will encompass said group of shots.

10. A method according to claim 9 further including the step of displaying an indication of validity or invalidity for said group of shots.

11. An apparatus for automatically aiding in conducting shot group firing practices with a weapon, said weapon being capable of firing a plurality of projectiles at an aiming point, said apparatus comprising: hit position detection means for determining where a projectile fired from said weapon passes through a vertical plane having a predetermined relationship with said aiming point and further being generally perpendicular to a line connecting said aiming point and said weapon; means, responsive to said detection means for recording the hit positions of at least two projectiles which constitute a shot group; means, responsive to said recording means for determining from said hit positions the size of the shot group; and means, responsive to said computing means, for displaying said size.

12. An apparatus according to claim 11, wherein at least three projectiles are fired and further wherein said computing means and displaying means respectively calculates and displays the hit position of each shot of the shot group after said three projectiles are fired.

13. An apparatus according to claim 11 or 12, wherein said means for determining the size of the shot group further determines the mean point of impact (MPI) of the shot group and the display means indicates said MPI.

14. An apparatus according to any one of claims 11 to 13, wherein said determining means includes means for computing the smallest circle which will encompass said projectile hit positions, for comparing said circle with a predetermined circle size and for providing an output indicating whether said hit positions comprise a valid or invalid shot group, said valid or invalid shot group being determined by whether the computed circle is smaller than or larger than said predetermined circle, respectively, and wherein said indicating means comprises a display means which is responsive to said circle computing means for visually indicating the validity or invalidity of the shot group.

15. A method of conducting shot group firing practices whereby a group of shots is fired so that the shots are grouped within a circle of predetermined diameter comprising: firing a group of shots at a hit position detector having an aiming point whereby said shots pass through a vertical plane spaced from said target; recording hit position information from each shot detected by said detector; determining the smallest circle which will encompass the hit positions detected for each shot group; indicating whether said circle is larger or smaller than a predetermined circle size.

16. A method according to claim 15, wherein the step of indicating further comprises indicating a valid group when said circle size is less than said predetermined size and indicating an invalid group when said circle size is greater than the predetermined size.

17. A method according to claim 15 or 16, including displaying the hit positions for each shot of a group after all the shots at the group have been fired.

18. A method according to any one of claims 15 to 17, including step of automatically progressing to a semi-automatic rifle zeroing exercise when a first predetermined number of groups of shots are determined to be valid.

19. A method according to any one of claims 15 to 18, including the step of automatically stopping the grouping exercise when a second predetermined number of groups of shots are determined to be invalid.

Drawing