A PATH

RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application No.

62/362,186, filed on July 14, 2016. The entire teachings of the above application are incorporated herein by reference.

BACKGROUND

[0002] While playing billiard games (e.g., carom billiards, snooker, pool, etc.), as a matter of strategy, players often desire or are required to apply sidespin (spin along the z- axis, or vertical axis) onto a cue ball. This spin is commonly referred to as "English" and is referred to herein as "spin." In order to apply spin, one must adjust one's aim in order to strike the cue ball with a cue stick on one side or the other of the ball's vertical center. This adjustment causes a distorted alignment from the desired path of the ball. Upon impact of the cue stick striking the cue ball off-center, both the cue stick and the cue ball deflect away from each other to varying degrees, depending on the relative masses between them. The deflected ball is redirected on a path that is at an angle, opposite to the spin being applied, to the path the ball would have taken if not stuck off-center. This deflection of the cue ball is commonly referred to as "squirt." Squirt makes it very challenging to predict the exact path of any such billiard shot. The exact degree of squirt is a function of physical properties of the cue stick's design, relating particularly to the cue stick's front-end mass and flexibility. However, the precise degree of deflection (squirt) of a cue is not a performance property that is customized, measured, or explicitly revealed to others by cue stick manufacturers. Rather the onus is on the user of the cue to adapt the user's compensation tactics to fit the properties of a cue through a lengthy process of trial and error. Cue sticks have not been explicitly designed with attention on how to make this process easier.

SUMMARY OF THE INVENTION

[0003] The disclosed apparatuses and methods detect deviation of a ball from a path, and are particularly useful when spin is applied to the ball. One example apparatus is a device that includes a support structure and detection members. The detection members are coupled to the support structure and arranged to allow a ball to travel between the detection members. At least one of the detection members is movable relative to the support structure and moves upon collision with the ball. The movement of at least one of the detection members indicates that the ball has deviated from a path of travel through the detection members. A displacement (movement) of at least one of the detection members can indicate the direction of deviation of the ball from the straight path of travel between the detection members, and an amplitude of movement of at least one of the detection members can indicate a degree of deviation of the ball from the straight path of travel between the detection members. The distance between the detection members can be adjustable to accommodate different size balls or the precision of deviation detection.

[0004] In many embodiments, the detection members are rotable about the support structure and rotate upon collision with the ball. In some embodiments, the rotational axes of the detection members are substantially vertical, and in others, the rotational axes are substantially horizontal. The support structure can include a substantially horizontal cross bar, and the detection members can be coupled to the cross bar and can hang downward from the cross bar. In an embodiment, the detection members may swing freely with respect to the cross bar or may be configured to remain in a displaced position after colliding with the ball. Many embodiments can also include a center alignment guide coupled to the cross bar to assist with placement of the ball to travel between the detection members. In many embodiments, the deviation of the ball is caused by an implement striking the ball to propel the ball and to induce spin on the ball. In an embodiment, a guide may be used to assist the implement in striking the ball from a consistent angle. An example of a ball and implement to be used with the disclosed devices are a cue ball and cue stick.

[0005] Another example apparatus is a device that includes a support structure and sensors. The sensors can be coupled to the support structure and arranged to allow a ball to travel between the sensors. The sensors are arranged to detect deviation of the ball from a path of travel through the sensors. The sensors may include, for example, lasers or optical sensors, such as photo sensors, and the distance between the sensors can be adjustable. In many embodiments, the support structure can include a substantially horizontal cross bar, and the sensors may be coupled to the cross bar and aimed downward from the cross bar.

Triggering of one of the sensors can indicate the direction of deviation of the ball from the path of travel between the sensors, and the sensors may measure a degree of deviation of the ball from the straight path of travel between the sensors.

[0006] An example method of detecting deviation of a ball from a path includes arranging a camera to capture video of the ball placed on a surface. The ball is struck with an implement to propel the ball along a desired path on the surface. Video of the ball is captured including when and after the ball is struck by the implement, and frames of the video are analyzed to determine whether the ball, when struck by the implement, deviation from the desired path. The method then reports whether the ball deviated from the desired path.

Analysis of the video frames may occur in real-time, and a direction or degree of deviation can be reported. An angle at which the implement struck the ball may also be determined and it can be reported whether the angle adequately compensated for deflection of the ball.

[0007] Another example method of detecting deviation of a ball from a path includes arranging a camera to capture video of a cue ball placed on a surface. The ball is struck with a cue stick to propel the ball along the surface and to induce spin on the ball. Video of the ball, path, and cue stick alignment is captured including when and after the ball is struck by the cue stick, and frames of the video are analyzed to determine how, and to what degree, the ball, when struck by the cue stick, was deflected by the cue stick. The method then reports both the angle of the cue stick and the angle of the ball path as it was deflected. The degree of compensation error can also be reported.

[0008] An example device for guiding a cue stick includes an apparatus that can include a bridge, a rail, and a slidable shuttle coupled to the rail. The bridge supports a fore end of the cue stick, and the slidable shuttle supports the cue stick at a point rearward of the fore end, where the cue stick is pivotable at the point of contact with the shuttle.

[0009] An example method of quantifying characteristics of a cue stick includes determining a balance point of the cue stick, determining a pivot point of the cue stick based on deflection characteristics of the cue stick, and assigning a value to the cue stick that quantifies a relationship between the balance point and the pivot point of the cue stick. Using the method of quantifying characteristics, a system of assigning values to cue sticks provides standardized cue sticks for selection and personalization of the cue sticks for their use in play. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The foregoing will be apparent from the following more particular description of example embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating embodiments of the present invention.

[0011] FIG. 1 A is a schematic drawing of a device for detecting deviation of a ball from a path, according to an example embodiment of the invention.

[0012] FIGS. 1B-D are schematic diagrams illustrating how the example device of FIG. 1 A can be used to detect deviation of a ball from a path and to calibrate compensation for deflection.

[0013] FIGS. 2A and 2B are schematic drawings illustrating how an example device can be used to detect deviation of a ball from a path and to calibrate compensation for deflection.

[0014] FIG. 2C illustrates quantifying characteristics of a cue stick.

[0015] FIG. 3 is a schematic drawing of a device for detecting deviation of a ball from a path, according to an example embodiment of the invention.

[0016] FIG. 4A is a schematic drawing of a device for detecting deviation of a ball from a path, according to an example embodiment of the invention.

[0017] FIG. 4B is a schematic drawing of a device for detecting deviation of a ball from a path, according to an example embodiment of the invention.

[0018] FIG. 5A is a schematic drawing of a device for detecting deviation of a ball from a path, according to an example embodiment of the invention.

[0019] FIG. 5B is a schematic drawing of a device for detecting deviation of a ball from a path, according to an example embodiment of the invention.

[0020] FIG. 6 is a schematic drawing of a device for detecting deviation of a ball from a path, according to an example embodiment of the invention.

[0021] FIG. 7A is a flow chart illustrating a method for detecting deviation of a ball from a path, according to an example embodiment of the invention.

[0022] FIG. 7B is a flow chart illustrating a method for detecting deviation of a ball from a path, according to an example embodiment of the invention.

[0023] FIGS. 8A-D are photographs of an example device for detecting deviation of a ball from a path, according to an example embodiment of the invention. [0024] FIG. 9 is a schematic drawing of a device for detecting deviation of a ball from a path, according to an example embodiment of the invention.

[0025] FIG. 10 is a schematic drawing illustrating a cue stick being used to lift and move the device of FIG. 9.

[0026] FIG. 11 is a schematic drawing of a device for detecting deviation of a ball from a path, according to an example embodiment of the invention.

[0027] FIG. 12 is a schematic drawing of a device for detecting deviation of a ball from a path, according to an example embodiment of the invention.

[0028] FIG. 13 is a schematic drawing of a device for detecting deviation of a ball from a path, according to an example embodiment of the invention.

[0029] FIGS. 14A-D are photographs of an example device for detecting deviation of a ball from a path, according to an example embodiment of the invention.

[0030] FIG. 15 is a schematic drawing of a device for detecting deviation of a ball from a path, according to an example embodiment of the invention.

[0031] FIG. 16 is a schematic drawing of a device for detecting deviation of a ball from a path, according to an example embodiment of the invention.

[0032] FIG. 17 is a schematic drawing illustrating how an example device can be used to detect deviation of a ball from a path and to calibrate compensation for deflection.

DETAILED DESCRIPTION OF THE INVENTION

[0033] A description of example embodiments of the invention follows.

[0034] As described above, when a cue stick impacts a cue ball off-center to, for example, induce spin on the ball, the cue stick, due to its different mass relative to the mass of the ball, displaces the ball at an angle directed away from the spin being applied. This redirection of the ball line away from the cue stick aiming line is referred to as a deflection of the cue ball, also known as "squirt." The deflection (or squirt) makes it challenging to predict the exact path of the ball. To complicate matters further, a spinning ball interacts with the table bed causing it to curve slightly back toward the original aiming line - an effect that reduces, or cancels, part of the original squirt. Unless the cue stick is significantly elevated, this "swerve" effect is barely noticeable over short distances and even less noticeable at faster speeds. It should be noted that the phenomena of cue ball swerve is related to the frictional properties of the ball and table and not directly linked to the properties of the cue stick. While practitioners must contend with the combined distortions of squirt and swerve

(sometimes called "squerve") when compensating for spin shots, it is important to be able to measure the extent that each distortion contributes individually in order to understand the overall process well.

[0035] The precise angle of adjustment required to make spin shots accurately depends considerably on the physical properties of the cue stick being used to strike the cue ball. There is a wide range of cue sticks available, each with varying degrees of end mass and flexibility, the main factors that affect deflection. Billiard cue stick manufacturers have historically prescribed a one-size-fits-all model to custom cue stick design with respect to deflection performance. There is a prevailing notion in some parts of the industry that the effects of squirt must necessarily be reduced to the point of elimination (zero-deflection) - a concept that is not physically realistic. The devices and methods described herein make it possible to quantify deflection, which can lead to a standardization and tailoring of deflection performance metrics in the cue stick manufacturing industry. Furthermore, the concepts and methods described herein demonstrate that the reduction of deflection is not necessarily optimal for certain individuals - depending on their form factor. For example, individuals of short stature (with shorter "wingspan") actually require higher deflection performance, while players with longer arms require lower deflection cues, in order to optimize their ability to compensate consistently.

[0036] Choosing an appropriate aiming alignment for each shot represents a major challenge for practitioners, and developing the ability to accomplish aiming alignment consistently and successfully usually has an extended learning curve because the mechanics of squirt (cue ball deflection) happen too quickly for the eye to see, making it difficult to gauge both the direction and degree of the squirt properly. Players, if they notice the effect at all, tend to incorrectly judge properly the nature of deflection such that they can consistently make a conscious and appropriate correction. The devices and methods described herein provide the observer with immediate feedback about spin alignment errors during practice, which allows for much higher quality training and successful development of a working sidespin compensation strategy.

[0037] FIG. 1 A is a schematic drawing of a device 100 for detecting deviation of a ball 105 from a path, according to an example embodiment of the invention. The device 100 includes a support structure 110 and detection members 115a,b. The detection members 115a,b are coupled to the support structure 110 and arranged to allow the ball 105 to travel between the detection members 115a,b. The detection members 115a,b are movable relative to the support structure 110 and move upon collision with the ball 105. In the embodiment of FIG. 1 A, the support structure 110 includes a substantially horizontal cross bar. In the example embodiment shown, the detection members 115a,b are coupled to the cross bar, hang downward from the cross bar, are rotable about the cross bar, and rotate upon collision with the ball. The distance between the detection members can be adjusted. An example use of the device 100 of FIG. 1 A is to analyze a billiard shot, in which case the ball 105 is a cue ball that is struck by a cue stick, that can induce spin on the ball 105. To use the device 100, a user places the ball 105 between the user and the device 100, strikes the ball 105 with an implement to, for example, induce spin on the ball and to propel the ball through the device 100. If the user has not adequately compensated for deflection of the ball 105 when the ball is struck off-center, then the ball 105 will collide with one of the detection members 115a and 115b. A user may typically place the ball 105 about one inch in front of the device 100, but can place the ball at any distance. Greater distances provide a more challenging use of the device because the ball 105 would have more of an opportunity to deviate from a desired path through the device before the ball 105 reaches the device 100.

[0038] In the case of FIG. 1 A, the detection members 115a,b swing freely back-and-forth (in and out of the page, from the perspective shown in FIG. 1 A), though in other

embodiments the detection members 115a,b may remain displaced after collision with the ball 105 by, for example, using a ratcheting mechanism. The movement of at least one of the detection members 115a,b indicates that the ball 105 has deviated from a path of travel through the detection members 115a,b. If, for example, detection member 115b is displaced after the ball 105 is propelled through the detection members 115a,b, the displacement of detection member 115b indicates that the direction of deviation of the ball 105 from the path of travel between the detection members 115a,b was to the right, toward detection member 115b. The amplitude of movement of the displaced detection member indicates a degree of deviation of the ball 105 from the path of travel between the detection members 115a,b. For example, if the ball 105 deviates only slightly to the right, the amplitude of movement of detection member 115b may only be slight because the ball 105 may only slightly nudge detection member 115b. On the other hand, if the degree of deviation is great, a substantial portion of the ball may impact detection member 1 15b and, thus, increase the amplitude of displacement of detection member 1 15b.

[0039] FIGS. 1B-D are schematic diagrams illustrating how the example device of FIG. 1 A can be used to detect deviation of a ball from a path and to calibrate compensation for deflection. FIG. IB shows how a user of the device 100 can position the ball 105 in front of the device at an arbitrary distance Y. The arbitrary distance may be about one inch, for example, but can be any distance depending on the preference of the user. FIG. IB also illustrates a "handle" 120 that may be included at the middle of the device 100. The handle 120 can be used to position and align the device and as a visual alignment tool for ball placement.

[0040] FIG. 1C illustrates, from a top view, the ball 105 being struck by an implement 125 to induce spin on the ball. As shown in FIG. 1C, the user of the implement 125 has not compensated for deflection (squirt) of the ball. FIG. ID illustrates, from a top view, the ball 105 being struck by an implement 125 to induce spin on the ball. As shown in FIG. ID, the user of the implement 125 has compensated for deflection (squirt) of the ball by pivoting the implement 125 about a pivot point 130.

[0041] FIGS. 2A and 2B are schematic drawings illustrating how an example device (e.g., the device 100 of FIG. 1A) can be used to detect deviation of a ball from a path and to calibrate compensation for deflection. FIG. 2B also shows an example bridge 230, mechanical rail 235, and sliding shuttle 240 that can be used alone or in combination as an apparatus to insure that a straight stroke of a cue stick is made.

[0042] FIG. 2A illustrates four aiming scenarios 200a-d. In each scenario, the dashed line 210a-d is a desired straight path of a ball 205a-d. The solid line 215a-d is the line of a cue stick, which necessarily must be angled away from the deflection effect at X degrees, which is an anticipated deflection. The dotted lines 220a-d are the paths of the cue ball 205a- d. The cue stick pivot points (target symbols) 225b-d show how manipulating the pivot point of a cue stick adjusts the angle of compensation. The four scenarios 200a-d illustrate how pivot point relates to a compensation strategy and leads to an understanding of an optimal cue stick for a particular person (giving rise to a "sizing" property of each cue stick). Each cue stick deflects a cue ball differently (according to the mass of the cue stick' s front end) and at an angle that is proportional to the tip offset applied during spin. A user can practice moving the user's hands laterally to learn how much the user must angle the user's cue when compensating for shots with spin.

[0043] With this concept in mind, a correct "size" cue stick for a user can be determined. Users angle their cue sticks in order to compensate for spin. This compensation is best made by basing their stick line on the same line as their desired cue ball path (dashed line) 210a-d. From this line, a user must move the user's bridge hand to point the tip to the cuing spot (on the cue ball) for the desired spin. This strategy (called Front-Hand-English or FF£E) creates an angle, which depends on the tip offset and the pivot point of the user's back hand. If the angle created by moving the user's front hand matches the natural squirt angle of the cue stick, then the cue ball will follow the desired path (dashed line) 210a-d. Otherwise, the user must move the user's back hand as well to achieve the correct compensation angle. Any cue stick that requires a user to move both hands can be considered less optimal because a compensation strategy of angling the cue will be a less repeatable task. Thus, a cue stick held at a pivot point that naturally creates the proper compensation angle that matches the deflection of the cue stick is optimal. The right match for a user allows the user to hold and stroke the cue at this pivot point, thus allowing the user to apply English by only moving the user's front (bridge) hand. The cue stick industry does not match cue stick deflection properties to a balanced location where individual users prefer to hold their cue sticks. The above concept enables a cue stick to be measured, standardized with a numbering type of system, and provided with an indication on the cue stick, which could be an indicator strip, for example, positioned at an optimal pivot point or range that naturally compensates for the deflection with FF£E and allows for personalized use of the cue stick based on the location of the indication. The user of a cue stick can then obtain a cue and, via the indicator, test whether the optimal pivot point for deflection compensation coincides with where the cue stick feels most balanced for the user. Cue sticks may also be provided with numbers that allow a user to select a cue according to where the user prefers to hold the cue (where it feels balanced), rather than adjust the user's pose or posture around the fixed properties of a given cue stick, particularly a cue stick that is not standardized or that does not allow for personalized use.

[0044] Because of this, it is possible to construct (or measure and label) a cue with specific properties that enable a simple and reliable compensation strategy to be applied while simultaneously matching the cue to a particular user given the varying sizes and forms of the wide range of users. A tailor-fit, balanced back-hand grip position, specifically designed to coincide with an optimal pivot point or range of the cue, that geometrically compensates for the natural squirt angle can be determined. A cue that satisfies these conditions can allow a user to more easily compensate for spin. Precise tools may be used to test and measure the effects and performance of cues, as described in conjunction with FIG. 2B. Also, an example set of functional parameters to reliably quantify the deflection performance and balance of cues is described in conjunction with FIG. 2C.

[0045] FIG. 2B shows an example bridge 230, mechanical rail 235, and sliding shuttle 240 that can be used to insure that a straight stroke of a cue stick is made. Such a device can be used when testing cue sticks for deflection performance, as described above. The mechanical rail 235 and sliding shuttle 240 can also be used with a bridge piece 230. As with FIG. 2A, the dashed lines 210e,f are a desired path of a ball, the solid lines 215e,f are the lines of a cue stick, the dotted lines 220e,f are the paths of the cue ball, and the cue stick pivot points (target symbols) 225e,f show how manipulating the pivot point of the cue stick adjusts the angle of compensation. The sliding shuttle 240 can be moved along the mechanical rail 235 to adjust the cue stick pivot point.

[0046] FIG. 2C illustrates an example "Standard Cuestick Deflection Specification" (SCDS) that can be used to quantify the deflection performance and balance of cues, according to an example embodiment of the invention. The typical pivot point for a billiard cue necessitates the movement of both hands to compensate for deflection due to the fact that the effect of squirt is very high with existing cue designs. According to the principles of the disclosed embodiments, compensating for squirt is much easier if a cue has a pivot point behind its balance point (where a user may prefer to grip the cue), thus enabling the user to move only the user's fore (bridge) hand. The following describes how the pivot and balance properties of a cue can be quantified.

[0047] An example cue stick specification format is <scale> p [+|-] b, where p is the pivot distance from tip in centimeters, and b the offset of balance point to grip hand in centimeters. See cue stick 250 in FIG. 2C for example cue stick measurements. The <scale> may be selected from C, P, and S, where C refers to Carom (61.5 mm diameter ball, 209 g), P refers to Pool (57.15 mm diameter ball, 156-170 g), and S refers to Snooker (52.5 mm diameter ball). As an example, a sample specification is "C120-10" where C refers to Carom, 120 is the pivot distance, and -10 is the balance point offset. [0048] After measuring the cue ball squirt characteristics of a particular cue stick, a specification for a cue stick can be designed that informs a user about the location of the stick's natural pivot point. The degree of cue ball squirt depends on the type of billiards to be played (e.g., Carom, Pool, Snooker) because the mass and size of the balls used in the different games changes the deflection angle experienced. A "C", P", or " S" specification prefix indicates this scale. With the squirt angle measured using the maximum tip offset for a given sized ball (RISE), an optimal pivot distance can be determined by using a table that gives the trigonometric relationship among cueing angle, tip offset (RISE), and the grip hand distance (RUN). An example of such a table 255 is shown in FIG. 2C. If the specification has a low pivot value (e.g., within the shaft of the stick), then a Back Hand English (BHE) strategy is called for. If the specification has a high pivot value (e.g., on the butt behind the balance point), then a Fore Hand English (FHE) strategy is called for. If the specification has a pivot value that sits between the bridge hand and the grip hand, then a combination

BHE/FHE strategy would be required. The relationship of the grip hand to the balance point is specified via a relative offset to the pivot point. If the balance point sits behind the pivot point, then the balance point offset is positive. If the balance point sits in front of the pivot point, then the balance point offset is negative. The above sample specification "C 120-10" denotes a carom cue with the optimal pivot point (grip) that is 120 cm (1200 mm) from the tip of the cue and 10 cm (100 mm) behind the balance point.

[0049] According to the above method, cue stick 260 has a SCDS of C60+41, meaning that for a Carom scale, cue stick 260 has a pivot length of 60 centimeters and a balance point 41 centimeters behind the pivot point. As described above, cue stick 260 has a pivot value that sits between a user' s bridge hand and grip hand and, thus, a combination BHE/FHE strategy is required. This configuration is not optimal as using both hands to predictably create angle settings is difficult to reproduce consistently.

[0050] According to the above method, cue stick 265 has a SCDS of C 120-10, meaning that for a Carom scale, cue stick 265 has a pivot length of 120 centimeters and a balance point 10 centimeters in front of the pivot point. As described above, cue stick 265 has a pivot point that is behind the balance point, which is desirable for applying FHE.

[0051] FIG. 3 is a schematic drawing of a device 300 for detecting deviation of a ball 305 from a path, according to an example embodiment of the invention. The device 300 is similar to that of FIG. 1 A and includes a support structure 310 and detection members 315a,b. The detection members 315a,b are coupled to the support structure 310 and arranged to allow the ball 305 to travel between the detection members 315a,b. The detection members 315a,b are movable relative to the support structure 310 and move upon collision with the ball 305. The device 300 of FIG. 3 also includes a center alignment guide 320 coupled to the cross bar of the support structure 310 to assist with placement of the ball 305. Such an alignment guide is not limited to the device 300 of FIG. 3, and can be included in any embodiment.

[0052] FIG. 4A is a schematic drawing of a device 400 for detecting deviation of a ball 405 from a path, according to an example embodiment of the invention. The device 400 includes a support structure 410 and detection members 415a,b. The detection members 415a,b are coupled to the support structure 410 and arranged to allow the ball 405 to travel between the detection members 415a,b. The detection members 415a,b are movable relative to the support structure 410 and move upon collision with the ball 405. In the embodiment of FIG. 4A, the detection members 415a,b are arranged to rotate about the support structure about substantially vertical axes. The movement of at least one of the detection members 415a,b indicates that the ball 405 has deviated from a path of travel through the detection members 415a,b. If, for example, detection member 415a is displaced after the ball 405 is propelled through the detection members 415a,b, the displacement of detection member 415a indicates that the direction of deviation of the ball 405 from the path of travel between the detection members 415a,b was to the left, toward detection member 415a. FIG. 4A shows the detection members 415a,b as having a straight vertical edge, but the detection members 415a,b may also have other shapes, such as a curved shape as shown in the embodiments of FIGS. 4A and 11.

[0053] FIG. 4B is a schematic drawing of a device 450 for detecting deviation of a ball 405 from a path, according to an example embodiment of the invention. The device 450 includes a support structure 460 and detection members 465a,b. The detection members 465a,b are coupled to the support structure 460 and arranged to allow the ball 405 to travel between the detection members 465a,b. The detection members 465a,b are movable relative to the support structure 460 and move upon collision with the ball 405. Similar to the device 400 of FIG. 4A, the detection members 465a,b are arranged to rotate about the support structure about substantially vertical axes. Movement of at least one of the detection members 465a,b indicates that the ball 405 has deviated from a path of travel through the detection members 465a,b. The detection members 465a,b of device 450 are shaped to substantially conform to the shape of the ball 405.

[0054] FIG. 5A is a schematic drawing of a device 500 for detecting deviation of a ball 505 from a path, according to an example embodiment of the invention. The device 500 includes a support structure 510 and sensors 515a,b. The sensors 515a,b are coupled to the support structure 510 and arranged to allow the ball 505 to travel between the sensors 515a,b. The sensors 515a,b detect deviation of the ball 505 from a path of travel through the sensors 515a,b. The sensors 515a,b may include, for example, lasers or optical sensors, such as photo sensors, and the distance between the sensors may be adjusted. The example device 500 of FIG. 5 A includes a substantially horizontal cross bar as part of the support structure 510. The sensors 515a,b are coupled to the cross bar and are aimed downward from the cross bar. If the ball 505 is deflected enough to trigger one of the sensors 515a,b, then the triggered sensor can indicate (e.g., by itself or through a display device) to an observer which direction the ball 505 deviated. The display device can be, for example, an audio or visual display device. The sensors 515a,b can also be configured to measure a degree of deviation of the ball 505 from the path of travel between the sensors 515a,b. One example way of determining a degree of deviation is to use multiple sensors on each side of the path of travel of the ball 505 through the device. For example, sensor 515b can include a plurality of sensors placed along the cross bar. If the deviation of the ball 505 is slight, the ball 505 may only trigger one (e.g., the inner-most sensor) of the plurality of sensors, but if the degree of deviation is great, the ball 505 may trigger multiple sensors. In addition to the sensors 515a,b, visual guides may be added to provide a user with visual representations of the detection member positions. Such visual guides can be, for example, thin barriers that hang down from the cross bar or that extend inward from the vertical portions of the support structure. Such visual guides can also provide additional feedback to the user by moving if the ball collides with them.

[0055] FIG. 5B is a schematic drawing of a device 550 for detecting deviation of a ball 505 from a path, according to an example embodiment of the invention. The device 550 includes a support structure 560 and sensors 565a,b. The sensors 565a,b are coupled to the support structure 560 and arranged to allow the ball 505 to travel between the sensors 565a,b. The sensors 565a,b detect deviation of the ball 505 from a path of travel through the sensors 565a,b. Similar to the device 500 of FIG. 5A, the sensors 565a,b may include, for example, lasers or optical sensors. The example device 550 includes a substantially horizontal cross bar as part of the support structure 560, and the sensors 565a,b are coupled to the cross bar and aimed downward from the cross bar. The device 550 also includes detection members 570a,b (left and right flaps) that are shaped to allow a user of the device 550 to visualize a space between the detection members 570a,b that form a "ghost ball target." The detection members 570a,b are configured to move when the ball 505 collides with either of the detection members 570a or 570b.

[0056] FIG. 6 is a schematic drawing of a device 600 for detecting deviation of a ball 605 from a path, according to an example embodiment of the invention. The device 600 includes a camera 610 arranged to capture video of the ball 605. When the ball 605 is struck with an implement 625 (e.g., cue stick) to propel the ball 605 along a surface and perhaps to induce spin on the ball 605, the camera 605 captures video of the ball 605. A processor 615 in communication with the camera 610 analyzes frames of the video to determine whether the ball 605, when struck by the implement 625, deviated from a desired path. A display device 620, such as a monitor, in communication with the processor 615 reports whether the ball 605 deviated from the path. The processor 615 can analyze the frames of the video in real-time, and can report via the display device 620 a direction and degree of deviation of the ball 605. The embodiment of FIG. 6, as well as any other embodiment, can be used with a guide 630 to assist the implement 625 in striking the ball 605 from a consistent angle. Further or other embodiments can use a linear actuator to cause the implement 625 to strike the ball 605. Use of such a linear actuator can help strike the ball 605 with a consistent force, which can be useful for testing purposes (e.g., testing for deflection characteristics of the implement 625).

[0057] FIG. 7A is a flow chart illustrating a method 700 of detecting deviation of a ball from a path, according to an example embodiment of the invention. According to the example method 700, a camera is arranged (705) to capture video of the ball placed on a surface. The ball is struck (710) with an implement to propel the ball along a desired path on the surface. Video of the ball is captured (715) while and after the ball is struck by the implement, and frames of the video are analyzed (720) to determine whether the ball, when struck by the implement, deviated from the desired path. The method then reports (725) whether the ball deviated from the desired path.

[0058] FIG. 7B is a flow chart illustrating a method 750 of detecting deviation of a ball from a path, according to an example embodiment of the invention. According to the example method 750, a camera is arranged (755) to capture video of the ball placed on a surface. The ball is struck (760) at a compensated angle with an implement to propel the ball along a desired path on the surface while inducing spin on the ball. Video of the ball, implement, and desired path is captured (765) including while and after the ball is struck by the implement, and frames of the video are analyzed (770) to determine deflection of the ball when struck by the implement, and to determine whether the compensation angle

appropriately compensated for the deflection. The method then reports (775) whether the compensation angle appropriately compensated, under compensated, or over compensated for the defection.

[0059] FIGS. 8A-D are photographs of an example device for detecting deviation of a ball (e.g., cue ball) from a path, according to an example embodiment of the invention. The example embodiment shown in FIGS. 8A-D is a gate-like device that includes a center alignment guide and an adjustable-width opening allowing for a ball to pass through. The opening can be adjusted to be more or less challenging. According to the example embodiment, two thin, lightweight, and freely-swinging detection members, hinged from a supporting bar above, one to the left and one to the right of the opening, serve as indicators that provide visual feedback telling a user if he has overcompensated, undercompensated, or correctly compensated for cue ball squirt. When the alignment or compensation is incorrect, the ball will collide with one of the detection members, causing it to swing on its hinges as the ball passes through. Depending on which English (left or right) was applied to the ball, the disturbance of a detection member indicates the nature and degree of stroking alignment issues or if the user has overcompensated or undercompensated for squirt. In general, if the user has under-compensated, the detection member opposite to the spin being applied is triggered, and if the user has over-compensated, the detection member on the same side as the spin being applied is triggered. The strength of the collision is an indication as to the degree of compensation error.

[0060] FIG. 9 is a schematic drawing of a device 900 for detecting deviation of a ball from a path, according to an example embodiment of the invention. The device 900 includes a support structure 910 and detection members 915a,b. The detection members 915a,b are coupled to the support structure 910 and arranged to allow a ball to travel between the detection members 915a,b. The detection members 915a,b are movable relative to the support structure 910 and move upon collision with a ball. In the embodiment of FIG. 9, the detection members 915a,b each includes a support bar with a hanging component to contact a ball. When a ball collides with a hanging component, the ball causes the hanging component to vibrate. The detection members 915a,b are in communication with respective

accelerometers 920a,b, which process vibration of the detection members 915a,b to determine an amplitude of vibration of the detection members 915a,b. The amplitude of movement is reported to a user of the device 900 via respective LED indicators 925a,b. According to the embodiment of FIG. 9, separate crossbars are used to isolate vibration signals of the respective detection members 915a,b. The bridge of the support structure 910 may be made of a vibration dampening material to further isolate signals between the accelerometers 920a,b. The LED display indicators 925a or 925b (e.g., in the form of digits or bars) indicate how severe the ball's contact was with a corresponding detection member 915a or 915b. For example, zero LEDs (or the number "0") can indicate no contact, while nine LEDs (or the number "9") can indicate hard contact. Bluetooth, or other wireless communications, can be used to transmit accelerometer readings to a mobile device (e.g., iPhone, iPad, or computer).

[0061] FIG. 10 is a schematic drawing illustrating a cue stick 1005 being used to lift and move the device 900 of FIG. 9. As shown in FIG. 10, a "handle" 930 may be included at the "voussoir" position in an archway (or middle of a crossbar) of the device 900. The handle 930 can be used to easily position the device into centered alignment and ready-to-use. The handle 930 may be a triangle-shaped tab, for example, with a channel, substantially perpendicular to the front plane of the device 900, passing through the handle 930. The channel is intended to be in-line with a user' s cue 1005 to enable the user to move and correctly align the device 900 using the fore end of a cue. Thus, the handle 930 can serve as a visual alignment tool for ball placement (centered in the archway and between the clear span of the device 900) or, as described above, as a handle with which a user may pick up and reposition the device 900 using the front of the cue stick 1005, for example. Such a handle is not limited to the embodiment of FIG. 9, and can be included in any other embodiment.

[0062] FIG. 1 1 is a schematic drawing of a device 1 100 for detecting deviation of a ball from a path, according to an example embodiment of the invention. Device 1 100 is similar to device 900, but the detection members 1 1 15a,b include thin plastic flaps connected to electronic accelerometers (not shown) and LED indicators 1 125a,b.

[0063] FIG. 12 is a schematic drawing of a device 1200 for detecting deviation of a ball from a path, according to an example embodiment of the invention. Device 1200 is similar to device 900, but the detection members 1215a,b include hanging spindles 1215a,b. The spindle configuration in FIG. 12 can be configured to optimize visual feedback.

[0064] FIG. 13 is a schematic drawing of a device 1300 for detecting deviation of a ball 1305 from a path, according to an example embodiment of the invention. Device 1300 includes a support structure 1310 and detection members 1315a,b. The detection members 1315a,b are coupled to the support structure 1310 and arranged to allow the ball 1305 to travel between the detection members 1315a,b. The detection members 1315a,b are movable relative to the support structure 1310 and move upon collision with the ball 1305. In the embodiment of FIG. 13, the support structure 1310 includes a substantially horizontal cross bar. In the example embodiment shown, the detection members 1315a,b are coupled to the cross bar, hang downward from the cross bar, and move upon collision with the ball 1305. The detection members 1315a,b are shaped to allow a user of the device 1300 to visualize a ghost ball target. The device 1300 also includes a center alignment guide 1320 coupled to the cross bar of the support structure 1310 to assist with placement of the ball 1305.

[0065] FIGS. 14A-D are photographs of an example device for detecting deviation of a ball (e.g., cue ball) from a path, according to an example embodiment of the invention. The example embodiment shown in FIGS. 14A-D is a gate-like device that includes a center alignment channel and an opening allowing for a ball to pass through. According to the example embodiment, two thin, lightweight detection members, coupled to a support structure, one to the left and one to the right of the opening, serve as indicators that provide visual feedback telling a user if he has overcompensated, undercompensated, or correctly compensated for cue ball squirt. When the alignment or compensation is incorrect, the ball will collide with one of the detection members, causing it to swing on its hinges as the ball passes through. Depending on which English (left or right) was applied to the ball, the disturbance of a detection member indicates the nature and degree of stroking alignment issues or if the user has overcompensated or undercompensated for squirt. In general, if the user has under-compensated, the detection member opposite to the spin being applied is triggered, and if the user has over-compensated, the detection member on the same side as the spin being applied is triggered. The strength of the collision is an indication as to the degree of compensation error. FIG. 14 D shows a user using the channel located at the center of the support structure to move and align the device using the fore end of a cue stick. [0066] FIG. 15 is a schematic drawing of a device 1500 for detecting deviation of a ball 1505 from a path, according to an example embodiment of the invention. The device 1500 includes a support structure 1510 and detection members 1515a-d. The detection members 1515a-d are coupled to the support structure 1510 and arranged to allow the ball 1505 to travel between the detection members 1515a-d. The detection members 1515a-d are movable relative to the support structure 1510 and move upon collision with the ball 1505. In the embodiment of FIG. 15, the detection members 1515a-d are arranged to rotate about the support structure about substantially vertical axes. The movement of at least one of the detection members 1515a-d indicates that the ball 1505 has deviated from a path of travel through the detection members 1515a-d. The device 1500 includes multiple layers of detection members. The first, foremost layer includes detection members 1515a and 1515. A second layer, behind the first layer, includes detection members 1515c and 1515d. The device 1500 can include any arbitrary number of such layers. FIG. 15 shows the detection members 1515a-d as having a straight vertical edge, but the detection members 1515a-d may also have other shapes, such as a curved shape as shown in the embodiments of FIG. 16. Further, the detection members 1515a-d, instead of being configured to rotate about substantially vertical axes, may be configured to rotate about substantially horizontal axes.

[0067] FIG. 16 is a schematic drawing of a device 1600 for detecting deviation of a ball from a path, according to an example embodiment of the invention. The device 1600 includes a support structure 1610 and detection members 1615a-d. The detection members 1615a-d are coupled to the support structure 1610 and arranged to allow the ball to travel between the detection members 1615a-d. The detection members 1615a-d are movable relative to the support structure 1610 and move upon collision with the ball. Similar to the device 1500 of FIG. 15, the detection members 1615a-d are arranged to rotate about the support structure about substantially vertical axes. Movement of at least one of the detection members 1615a-d indicates that the ball has deviated from a path of travel through the detection members 1615a-d. The device 1600 includes multiple layers of detection members. The first, foremost layer includes detection members 1615a and 1615. A second layer, behind the first layer, includes detection members 1615c and 1615d. The device 1600 can include any arbitrary number of such layers. The detection members 1615a-d of device 1600 are shaped to substantially conform to the shape of the ball. The detection members 1615a-d, instead of being configured to rotate about substantially vertical axes, may be configured to rotate about substantially horizontal axes.

[0068] FIG. 17 is a schematic drawing illustrating how an example device (such as, for example, device 1500 or 1600 of FIGS. 15 and 16) can be used to detect deviation of a ball from a path. FIG. 17 illustrates a top view of an example device including multiple layers of detection members, in this case two layers. The first, foremost layer includes detection members 1715a and 1715b. A second layer, behind the first layer, includes detection members 1715c and 1715d. Such a device with multiple layers can provide more information regarding alignment and the direction of deviation of a ball 1705. The detection members of any one layer can only be triggered one at a time (or not at all if the ball passes perfectly through the gap); however, a second detection member layer can provide further information about misalignment errors. For example, if the ball 1705 is struck along path 1720, the ball will not collide with any of the detection members 1715a-d. As a further example, if the ball 1705 is struck along path 1725, the ball with collide with either 1715a, or 1715c, or both. If the ball 1705, traveling along path 1725, happens to pass through detection members 1715a and 1715b without colliding with either detection member 1715a or 1715b, then the ball will still collide with detection member 1715c. Likewise, if the ball 1705, traveling along path 1730, happens to pass through detection members 1715a and 1715b without colliding with either detection member 1715a or 1715b, then the ball will still collide with detection member 1715d.

[0069] While this invention has been particularly shown and described with references to example embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims. While the above example embodiments relate to use in billiards, the disclosed devices and methods are not so limited and could be applied in other situations involving detecting deviation of a ball, such as, for example, golf.