Abstract:
An essential element of sharpshooter training is the reduction of quivering of the firearm. Such quivering or jitter is caused by inadvertent movement of the shooter while holding the firearm. Embodiments of the present invention comprise a motion sensing device that is attached to the firearm to produce visual and aural feedback to the shooter on the degree of gun shake. The shooter can thus practice different shooting stances, muscle control, and breathing techniques, and use the feedback from the gun shake sensor to evaluate and adjust these parameters. This training aid improves firearm accuracy without the need for stands, stabilizers, or other aids. The training aid can be rapidly attached to, and removed from any firearm.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates generally to weapons training systems, and more particularly to training aids for use in the field of firearms, archery, and related activities. 
         [0003]    Good marksmanship is essential not only for the success of police and military forces, but also for sport and target shooting. A key issue in marksmanship training is the attainment of a steady firing position. This involves many variables, including selection of firing position, muscle tension, control of breathing, and consciousness of heart beat. The steady position must be attained for a period of time up to, including, and just after the discharge of the firearm. One purpose of embodiments according to the present invention is to provide a training aid that can rapidly improve control of gun shake during all these three phases, thereby improving marksmanship. 
         [0004]    2. Statement of the Prior Art 
         [0005]    In the prior art, there is substantially clear evidence that gun shake is the major cause of poor accuracy, especially in offhand (i.e., unsupported) shooting. However, conventional solutions to this problem often come in one of two forms. Tedious repetitive training is one of these conventional forms. Various aids to stabilize the gun mechanically is the other. 
         [0006]    Several devices have been proposed in the art to actively stabilize firearms ranging from simple slings and tripods to gyroscopic sensors and servo mechanisms. All these aids increase complexity and often require power sources. Other methods include special handgrips and stabilizing aids. All these devices also require the firearm to be significantly modified. In any event, such devices would not be permitted in competition. 
         [0007]    There remains a fundamental need to improve shooting accuracy. Improving accuracy requires better control of gun shake. Despite the advances of technology resulting in better optics, laser aided-sights, there has been no advance in the training of shooting techniques, both for firearms, as well as archery. Traditional techniques used for hundreds of years are still used to teach basic marksmanship skills. These techniques require the shooting of thousands of practice rounds at targets in the hope that the student will somehow develop the correct stance and breathing control needed. The difficulty is that the shooter has no quantifiable feedback on the jitter or shake of the gun, but instead must resort to a “hit or miss” strategy based on evaluating the accuracy of shots fired on a target. This repetitive, tedious, and costly training is currently the only way to evolve better shooting accuracy. 
         [0008]    It is well known from numerous biofeedback studies, in diverse areas from sleep disorders to memory improvement, that if suitable feedback is provided, then it is possible to rapidly learn new behaviors and correct bad habits. In the absence of feedback, the user has no means of assessing and correcting these deficiencies. 
         [0009]    Thus, there exists a need for a marksmanship training aid that can provide feedback to the shooter on the relative movement of the firearm so that he/she can adjust their stance and control their breathing to better stabilize the firearm, and thereby increase their potential accuracy. 
       SUMMARY OF THE INVENTION 
       [0010]    These and other objects, advantages, and novel features are provided by embodiments of the present invention, which overcome all these difficulties and provides all the desired features by measuring firearm shake using gyroscopic motions sensors. These sensors measure the rate of change about at least two orthogonal axes. The gyroscopes quantify shaking of the weapon in up-and-down, and side-to-side direction by using inertial measurements of a rate of change. The rate of change signals are compared to a user set threshold and an audio tone warns the user when the firearm is shaking beyond the user set limit. Use of auditory feedback ensures that the user is not visually distracted in any way from the target. 
         [0011]    In practice, the user attaches the training device to a firearm and practices holding it steady in a variety of positions. The objective is to hold the firearm steady enough that the audio tone is no longer heard (i.e., “gun steady”), and then continue to hold it steady for as long as possible. Once the gun shakes, the resumption of the audio tone indicates to the user that the exercise is over and they can now lower the firearm and examine the displayed elapsed “steady” time. The user can then repeat the exercise in an effort to improve the “steady time”. Breathing and heartbeat timing can be quantified and alternate positions evaluated scientifically. Muscle tension and strength can be studied. The user can also evaluate how steady they can hold the weapon during all three critical phases of firearm operation—1) acquire target; 2) aim, and 3) pull trigger and follow through. 
         [0012]    The feedback provided by embodiments of the present invention can rapidly improve marksmanship skills. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The foregoing and other features of the present invention will become more apparent from the following description of exemplary embodiments, as illustrated in the accompanying drawings wherein: 
           [0014]      FIG. 1  is a perspective view of the marksmanship training aid mounted on the right side of the firearm; 
           [0015]      FIG. 2  shows the orientation of the gyroscopes relative to movement of the gun barrel; and 
           [0016]      FIG. 3  is a schematic view of various components of the marksmanship training aid according to embodiments of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0017]    Exemplary embodiments are discussed in detail below. While specific exemplary embodiments are discussed, it should be understood that this is done for illustration purposes only. In describing and illustrating the exemplary embodiments, specific terminology is employed for the sake of clarity. However, the embodiments are not intended to be limited to the specific terminology so selected. Persons of ordinary skill in the relevant art will recognize that other components and configurations may be used without departing from the true spirit and scope of the embodiments. It is to be understood that each specific element includes all technical equivalents that operate in a similar manner to accomplish a similar purpose. Therefore, the examples and embodiments described herein are non-limiting examples. 
         [0018]    Referring now to the drawings, wherein like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements, there is shown in  FIG. 1  an aiming device  10  according to one embodiment of the present invention. 
         [0019]    Aiming device or marksmanship training aid  10  generally comprises a gun shake detector suitable for installation on a firearm, typically using a clamp around the barrel, or mounted on a Picatinny or Weaver rail. It may also be used on a crossbow, archery bow, or camera. It suitably comprises a gyroscopic sensor module that detects rate of change around at least two orthogonal axes, a module capable of generating an audio tone and visual signal in response to the rate data, and a display module that shows the elapsed time that the gun has successfully been held steady. 
         [0020]    One embodiment of the present invention is shown in  FIG. 1 . The marksmanship training aid  10  is mounted on the right side of the firearm  20  in substantial alignment with the firearm barrel  18 . It could equally be mounted on the left side of the firearm  20  for left-handed shooters. 
         [0021]    Referring to  FIG. 2 , the device comprises two gyroscopes  30 ,  31  to measure the rate of change in the x and y-axis. Gyroscope  30  is mounted such that it is aligned perpendicular to the axis of the gun barrel  18  in the horizontal plane (i.e., the x-axis). Thus, it is most sensitive to up-and-down movements of the gun barrel. The second gyroscope  31  is mounted in an orthogonal position in the vertical plane (i.e., the y-axis) so that it is most sensitive to side-to-side movement of the firearm. A third gyroscope (not shown) could be added to measure the rate of roll of the gun barrel in the z-axis. Roll jitter is not very pronounced in a handheld firearm and measurement about this third axis may be omitted without departing from the spirit of the present invention. 
         [0022]    One ideal position would be to attach the marksmanship training aid  10  at the natural fulcrum of the handheld firearm. Referring again to  FIG. 2 , in the case of a rifle, this point  68 , is approximately where the non-firing (i.e., support) hand is placed on the stock. Placing the gyroscopes at position  68  in the orientation depicted would provide the greatest sensitivity to detect firearm shake. However, in practice, any convenient point as close as possible to the natural fulcrum may be used without a significant loss in sensitivity. This allows for the training device to be mounted on almost any firearm without any need for modification. The natural fulcrum of a pistol or bow may also be readily determined to provide a suitable location for use of the marksmanship training aid  10  on such weapons. 
         [0023]    Referring back to  FIG. 1 . when the firearm is held by the user and aimed at target  40 , the unavoidable jitter or shake would cause the projected bullet trajectory to vary from the true course  26  to some arbitrary trajectories as typified by  25  and  27 . This accuracy can be related to angular movement of the firearm due to shake and is quantified by the term “minute of arc” or MOA. As is well known, MOA is a unit of angular measurement used in the firearms industry on scopes or firearms to define shooting accuracy. It is popular because 1 MOA almost equals one inch (1.0472 inches to be more precise) at 100 yards. With a rifle clamped to a rest so that it is completely steady, it is possible to get an accuracy of better then ½ MOA. With a handheld firearm, the typical accuracy degrades to as low as 4 MOA due to gun shake. A well trained and skilled sharpshooter is able to get 1 MOA using a handheld position, but this is very difficult to achieve for most shooters using current training methods. 
         [0024]    The marksmanship training aid  10  according to embodiments of the present invention measures angular movement about the x- and y-axes of the gyroscope sensing module mounted on the firearm. The gyroscopes in this module output the rate of change about their respective axes. If the firearm is completely steady then the output from either gyroscope is zero. Any movement of the gun about the x- and y-axis causes the gyroscopes to produce a voltage signal proportional to the rate of change about the respective axes. 
         [0025]    Referring to the schematic diagram in  FIG. 3 , the rate of change output from each gyroscope  30 ,  31  may be fed to a window comparator circuit. The rate of change is compared to a user set value input using potentiometer  52 . If the rate of change is greater than the user set value, then the comparator  32  (x-axis) and comparator  33  (y-axis) produces an output indicating that the input from each respective gyroscope is outside the set threshold. This error output is fed to a microprocessor  34  that produces a tone using speaker  35  or earpiece  36 . It also activates a visual indicator by lighting LED  37 . The user holds the gun steady until the audible tone is silent. This indicates that the gun movement is less than the user-set threshold and may be considered to be steady. After the gun is steady for at least one second, a software timer may count the number of seconds the gun remains steady, and show this elapsed or “steady” time on display  12 . If the gun moves more that the rate set by the user threshold setting, then the timer stops, and the shooter can read the elapsed seconds (shown as “09” in  FIG. 3 ) on display  12  to determine their performance on the exercise. This numeric feedback is important in order for the shooter to strive for a longer and longer “steady” time, thereby increasing their skill level. Different firing positions, firearm holding techniques, and muscle tension can be evaluated based on the time the gun can be held steady. Movement due to breathing and heartbeat may also be evaluated and suitable techniques developed to compensate for shake due to these necessary bodily movements. Pressing button  36  resets the timer to zero and the shooter is ready for another exercise. Alternatively, the device may be configured to reset itself automatically after a few seconds. 
         [0026]    A MEMS single-chip dual-axis gyroscope (e.g., Invensense, IDG-1123, Invensense Inc, Sunnyvale, Calif.) may be used according to one presently preferred embodiment. Rotating this chip about the orthogonal x and y axes results in a Coriolis force on the corresponding x- or y-rate sensor. This gyroscope chip provides an output of 23 mV/degree/sec on each independent axis. Various capacitors may be used to provide low- and high-pass filters to limit the response from 10 Hz to 200 kHz. This limits high frequency noise, and provides an optimal range for detecting human-induced shake. 
         [0027]    In principle, any gyroscopic sensor may be used, the only restriction being that it must measure at least two orthogonal axes independently and these axes must be aligned substantially as shown in  FIG. 2 . Two window comparator chips (e.g., LTC-1042, Linear Technology Corp, Milpitas, Calif.) may be used to detect movements outside the user set threshold. A 16PIC628 microprocessor manufactured by Microchip Inc., Chandler, Ariz. may be used to generate the audio tone and to time the comparator signals. 
         [0028]    Microprocessor  34  suitably displays the elapsed time on, for example, a 7-segment LED display. The entire device  10  may be powered by a battery. In one alternative embodiment, the LED display  12  may be eliminated, and the elapsed time may be spoken through a speaker  35  or ear phone  36  using appropriate voice-synthesis algorithms. One advantage of the foregoing alternate embodiment is that the user does not have to take his attention away from sighting the firearm to view the elapsed time count, but can simply hear it. 
         [0029]    It should be understood that the foregoing description is only illustrative of embodiments of the present invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the spirit of the invention. Even handheld aiming of cameras would benefit from this invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.