CA2484674A1 - Method and apparatus for locating the trajectory of an object in motion - Google Patents
Method and apparatus for locating the trajectory of an object in motion Download PDFInfo
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- CA2484674A1 CA2484674A1 CA 2484674 CA2484674A CA2484674A1 CA 2484674 A1 CA2484674 A1 CA 2484674A1 CA 2484674 CA2484674 CA 2484674 CA 2484674 A CA2484674 A CA 2484674A CA 2484674 A1 CA2484674 A1 CA 2484674A1
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- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B24/00—Electric or electronic controls for exercising apparatus of preceding groups; Controlling or monitoring of exercises, sportive games, training or athletic performances
- A63B24/0021—Tracking a path or terminating locations
-
- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B69/00—Training appliances or apparatus for special sports
- A63B69/36—Training appliances or apparatus for special sports for golf
- A63B69/3658—Means associated with the ball for indicating or measuring, e.g. speed, direction
-
- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B24/00—Electric or electronic controls for exercising apparatus of preceding groups; Controlling or monitoring of exercises, sportive games, training or athletic performances
- A63B24/0021—Tracking a path or terminating locations
- A63B2024/0028—Tracking the path of an object, e.g. a ball inside a soccer pitch
- A63B2024/0031—Tracking the path of an object, e.g. a ball inside a soccer pitch at the starting point
-
- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B24/00—Electric or electronic controls for exercising apparatus of preceding groups; Controlling or monitoring of exercises, sportive games, training or athletic performances
- A63B24/0021—Tracking a path or terminating locations
- A63B2024/0028—Tracking the path of an object, e.g. a ball inside a soccer pitch
- A63B2024/0034—Tracking the path of an object, e.g. a ball inside a soccer pitch during flight
-
- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B69/00—Training appliances or apparatus for special sports
- A63B69/0002—Training appliances or apparatus for special sports for baseball
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- Health & Medical Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Physical Education & Sports Medicine (AREA)
- Life Sciences & Earth Sciences (AREA)
- Biophysics (AREA)
- Length Measuring Devices By Optical Means (AREA)
Abstract
An object locating system detects the presence of an object as it passes through two consecutive planar fields of view. Two pairs of optical sensor arrays with multiple, directed, pixel detectors observe the object from two angles as the object passes through each consecutive field of view. The locations of penetrations of the respective fields of view are calculated by triangulation. Using this data, the known location of the take-off point and/or the delay between penetrations, the trajectory of the object in time and space is calculated.
Applications include projecting the range of a driven golf ball, measuring the respective arriving and departing velocities of a hit baseball, and determining the trajectory and origin of an arriving projectile, as in the case of the threat to a military vehicle.
Applications include projecting the range of a driven golf ball, measuring the respective arriving and departing velocities of a hit baseball, and determining the trajectory and origin of an arriving projectile, as in the case of the threat to a military vehicle.
Description
TITLE: iVlethod and Apparatus far Locating the Trajectory of an Object in Motion.
FIELD OF THE INVENTION
[0001 ] This invention relates to a detection system fox determining the position, velocity and trajectory in space of moving objects, such as golf balls and baseballs for the purpose of training and practicing as well as other objects such as the detection of projectiles approaching a vehicle. It can also be used to evaluate the mechanical characteristics of a baseball bat, tennis racket, ox the like by comparing the ball's velocity before and after the collision with the baseball bat or racket, etc. Moreover, it can accurately determine whether ox not a baseball crosses the strike zone by tracking its trajectory in front of the home plate.
BACKGROUND TO THE INVENTIt~N
FIELD OF THE INVENTION
[0001 ] This invention relates to a detection system fox determining the position, velocity and trajectory in space of moving objects, such as golf balls and baseballs for the purpose of training and practicing as well as other objects such as the detection of projectiles approaching a vehicle. It can also be used to evaluate the mechanical characteristics of a baseball bat, tennis racket, ox the like by comparing the ball's velocity before and after the collision with the baseball bat or racket, etc. Moreover, it can accurately determine whether ox not a baseball crosses the strike zone by tracking its trajectory in front of the home plate.
BACKGROUND TO THE INVENTIt~N
[0002] Numerous systems exist for tracking a golf ball and estimating its range. Their main purpose is to give golfers a graphic and/or numeric display indicating their drive's effectiveness when they practice or play.
[00031 U.S. Patent No. 5,303,924 describes a golf game apparatus that simulates a total golf shot distance based upon the actual flight of a struck golf ball at a practice range, projecting the flight distance of the ball to an initial impact position on a target area. A
microphone in the area detects the take off of the ball stz~uck by the club head, and an array of microphones in the target area detects its arrival. The time between the two events can be correlated to the range.
The system requires a semi-permanent installation.
[0004] U.S. Patent No. 5,413,345 describes a system that identifies, tracks, displays and records all or selected portions of the path of one ox more golf balls. It performs these functions from the time each ball is struck, or a$er it is in flight, until it reaches the final point of rest. It uses an array of high-speed cameras installed on the green.
[0405] U.S. Patent No. 5,472,205 describes a system that detects the club head offset angle relative to a desired club head axis as well as the speed of club head by sag light reflected from the underside of the club head and processing this information electronically. The latter can be used to calculate the ball's speed by assuming an efficiency of momentum transfer from the club head to the ball. The system requires a semi-permanent installation.
[0006] U.S. Patent No. 5,489,099 describes a system comprising a video camera, a video processor and a flight path predictor. A video camera Locks onto the ball and tracks it while being rotated by an automatic control system.
[0007] U.S. Patent No. 5,846,139 describes a golf simulator consisting of three arrays of infrared receivers and emitters installed in an enclosure providing a shield from the ambient light. The system determines the ball's velocity vector. It requires a permanent installation.
[0008] U.S. Patent No. 5,926,780 describes a system for measuring a ball's velocity vector.
It consists of two arrays of Light sensors illuminated from above by two light sources. When the ball is struck, it flies over the two arrays and casts a shadow over a few sensors. Their location in the array and the position of the light sources allows the calculation of the ball's velocity vector. The patent does not address the exposure of the arrays to the ambient light. The system requires a semi-permanent installation.
[0009] U.S. Fatent No. 5,938,545 describes a system comprising two video cameras mounted on a golf cart. Their fields of view overlap and they track the ball by successive frame scans. The ball's trajectory is determined with respect to the cart, which is at an angle with respect to the launch pointer target line and at a certain distance from this reference point. This angle and this distance must both be known in order to relate the trajectory to the target line and to the position of the golfer. The system does not address the saturation effect of the sun on the area CCD sensor in the camera.
[0010] U.S. Patent No. 6,012,987 describes an electronic surveillance camera and a motion sensor above the green. Signals from the camera and the motion sensor are txansmitted to a processing unit. The latter generates the movement of an object on a video screen. The system requires a semi-permanent installation.
[0011] U,S. Patent No. 6,093,923 describes two or mare video cameras installed on a drive range tracking a golf ball within their fields of view. The system then electronically simulates the ball's trajectory to determine the ball's probable point of impact.
[OOI2] U.S. Patent No. 6,520,864 describes a video camera tracking a golf ball against a IO stationary background. A computer processes the video signal. to detect the golf ball and to automatically determine its trajectory.
[0013] Reference [1]: Barras, Ch., Localisation optique d'objets rapproch6s animes dune grande vitesse (Optical location finding of high-velocity objects at close range), Institut franco-allemand de recherche de Saint-Louis (Franco-German Research Institute Saint-Louis), report S-R 904192. Though arising in a field unrelated to the tracking of out-going objects, this reference [lJ describes a system for protecting a military vehicle consisting of a pair of photodiode arrays with lenses that form fan-shaped fields of view overlapping in a single plane.
It can detect at close range the position of an incoming projectile aimed at a vehicle. However, it cannot determine the velocity, nor the direction of the threat.
(_0014] Reference [2]: European patent application by Giat Industries, FP 1 096 2I 9 A 1.
Inventors: Lefebvre, Gerald and lVluller, Sylvain; Proeede et systems pour detecter acne menace tires sur un objet fire ou mobile. (Method and system far detecting a threat fared at a stationary cir moving object). Applicant, Publication date: 2001-05-10. 'This reference [2j describes a similar military-focus system concerning incotxzing objects in which two arrays with lenses installed on either side of the front of a military vehicle define four vertical intersecting fields of view: It explains how measuring the time when a projectile penetrates each planar field of view and knowing the angle between the lines joining the penetration points to the sensors, on the one hand, and the horizontal plane, on the other hand, provides sufficient information for calculating the position of the projected penetration points and the velocity vector of the incoming projectile. This system covers only a military application related to the calculation of an incoming projectile's position and velocity vector, wherein the trajectory is assumed to be linear. This reference relies upon making four successive time measurements. This reference does not address the determination of the path of an outgoing object, much Iess determining a projected trajectory calculated as a parabola corrected for aerodynamic drag. Furthermore, this patent application does not mention how to prevent the over saturation of the diode array when the image of the sun is focused on it.
[4015] There is a need for a sports training system fox tracking an object in space that does not xequire a semi-permanent installation, but can be set up and ready for use in a shoat time and within a limited space. Such a system can facilitate the training of baseball playexs, tennis players and players of other sports based upon control of a projectile. The device could also be used in the evaluation of the mechanical propexties of a baseball bat, golf club, tennis racket, ox other device used for striking an incoming projectile.
[0016] Imaging systems can form an image of an object on a planar surface, as in the case of a charge-coupled device, CCD, employed in a video camera. Such planar images require time to sample all of the pixels available in an x, y stray. Simpler imaging systems utilize a linear array that provides a far smaller number of. pixel sensors. The sampling time is accordingly substantially reduced. However, such known linear arrays can only sample a planar surface in space, viewed edge-on.
[0017] Such linear arrays can be provided with directed pixel sensors, aligned to divide the surface of the viewing plane into a discrete number of viewing sectors. Thus an 82.4-degree field of view divided amongst 512 directed pixel sensors will allow each directed sensor to detect an object present within a detection zone having an average angular dimension of 0.161 degrees within the detection plane.
[00183 While providing some image information with respect to the location of an object in space, the full location of an object, much less its firajectory, cannot be defined through use of a single linear array of directed pixel sensors. This invention addresses a method by which multiple linear arrays having directed pixel sensors rnay be utilized to obtain more information about the location of an object, and according to variants, defining not only its instantaneous location in space, but also its path of travel, local velocity and ultimate trajectory.
[0019] The invention in its general form will first be described, and then its implementation in terms of specific embodiments will be detailed with reference to the drawings following hereafter. These embodiments axe intended to demonstrate the principle of the invention, and the manner of its implementation. The invention in its broadest and more specific forms will then be further described, and defined, in each of the individual claims which conclude this Specification.
SUMMARY OF THE INVENTION
to [0020] According to the invention in a first variant, two linear detection optical sensor arrays, each having a plurality of directed pixel sensors, are positioned to provide overlapping fields of view in or substantially within a common, shared, planar field of view. By triangulation, the position of the object within the common field of view caa~
then be calculated.
I S Knowing the baseline between the two detection arrays and the angular orientation in space of the common field of view, the precise position in space of the object can be calculated and the time of its penetration of such field can be recorded.
[0021 ] The respective fields of view of the two linear detection arrays need not be precisely 24 co-planar. If such ,fields of view are sufficiently proximate to each other an object of finite length may simultaneously be detected in both fields. Furthermore, taking the hypothetical case of an infnitely small object, floe consecutive detection of the object by the first and second arrays over a very short interval can be taken, as an approximation, as being simultaneous. lxi either case, by treating the respective fields of view as ifthey were coplanar, the location of the 25 object in space can be calculated.
[0022] According to a feature of the invention, two linear detection arrays may be said to constitute a "set of arrays". By employing a pair of such sets, each set providing respective, shared, common fields of view, an accurate xzleasurement can be made of the position of the 30 tracked object at two locations. This can be used to establish the local trajectory or the line of travel of an object. In the case of a launched projectile, e.g. a golf ball, for which the takeoff point is known, the initial parabolic path of such projectile can be established without taking time measurements. Recording the time between the successive intersections of the object with the respective common fields of view allows the object's immediate velocity to be established.
35 This provides a further means for determining the initial parabolic path of a projectile.
[00031 U.S. Patent No. 5,303,924 describes a golf game apparatus that simulates a total golf shot distance based upon the actual flight of a struck golf ball at a practice range, projecting the flight distance of the ball to an initial impact position on a target area. A
microphone in the area detects the take off of the ball stz~uck by the club head, and an array of microphones in the target area detects its arrival. The time between the two events can be correlated to the range.
The system requires a semi-permanent installation.
[0004] U.S. Patent No. 5,413,345 describes a system that identifies, tracks, displays and records all or selected portions of the path of one ox more golf balls. It performs these functions from the time each ball is struck, or a$er it is in flight, until it reaches the final point of rest. It uses an array of high-speed cameras installed on the green.
[0405] U.S. Patent No. 5,472,205 describes a system that detects the club head offset angle relative to a desired club head axis as well as the speed of club head by sag light reflected from the underside of the club head and processing this information electronically. The latter can be used to calculate the ball's speed by assuming an efficiency of momentum transfer from the club head to the ball. The system requires a semi-permanent installation.
[0006] U.S. Patent No. 5,489,099 describes a system comprising a video camera, a video processor and a flight path predictor. A video camera Locks onto the ball and tracks it while being rotated by an automatic control system.
[0007] U.S. Patent No. 5,846,139 describes a golf simulator consisting of three arrays of infrared receivers and emitters installed in an enclosure providing a shield from the ambient light. The system determines the ball's velocity vector. It requires a permanent installation.
[0008] U.S. Patent No. 5,926,780 describes a system for measuring a ball's velocity vector.
It consists of two arrays of Light sensors illuminated from above by two light sources. When the ball is struck, it flies over the two arrays and casts a shadow over a few sensors. Their location in the array and the position of the light sources allows the calculation of the ball's velocity vector. The patent does not address the exposure of the arrays to the ambient light. The system requires a semi-permanent installation.
[0009] U.S. Fatent No. 5,938,545 describes a system comprising two video cameras mounted on a golf cart. Their fields of view overlap and they track the ball by successive frame scans. The ball's trajectory is determined with respect to the cart, which is at an angle with respect to the launch pointer target line and at a certain distance from this reference point. This angle and this distance must both be known in order to relate the trajectory to the target line and to the position of the golfer. The system does not address the saturation effect of the sun on the area CCD sensor in the camera.
[0010] U.S. Patent No. 6,012,987 describes an electronic surveillance camera and a motion sensor above the green. Signals from the camera and the motion sensor are txansmitted to a processing unit. The latter generates the movement of an object on a video screen. The system requires a semi-permanent installation.
[0011] U,S. Patent No. 6,093,923 describes two or mare video cameras installed on a drive range tracking a golf ball within their fields of view. The system then electronically simulates the ball's trajectory to determine the ball's probable point of impact.
[OOI2] U.S. Patent No. 6,520,864 describes a video camera tracking a golf ball against a IO stationary background. A computer processes the video signal. to detect the golf ball and to automatically determine its trajectory.
[0013] Reference [1]: Barras, Ch., Localisation optique d'objets rapproch6s animes dune grande vitesse (Optical location finding of high-velocity objects at close range), Institut franco-allemand de recherche de Saint-Louis (Franco-German Research Institute Saint-Louis), report S-R 904192. Though arising in a field unrelated to the tracking of out-going objects, this reference [lJ describes a system for protecting a military vehicle consisting of a pair of photodiode arrays with lenses that form fan-shaped fields of view overlapping in a single plane.
It can detect at close range the position of an incoming projectile aimed at a vehicle. However, it cannot determine the velocity, nor the direction of the threat.
(_0014] Reference [2]: European patent application by Giat Industries, FP 1 096 2I 9 A 1.
Inventors: Lefebvre, Gerald and lVluller, Sylvain; Proeede et systems pour detecter acne menace tires sur un objet fire ou mobile. (Method and system far detecting a threat fared at a stationary cir moving object). Applicant, Publication date: 2001-05-10. 'This reference [2j describes a similar military-focus system concerning incotxzing objects in which two arrays with lenses installed on either side of the front of a military vehicle define four vertical intersecting fields of view: It explains how measuring the time when a projectile penetrates each planar field of view and knowing the angle between the lines joining the penetration points to the sensors, on the one hand, and the horizontal plane, on the other hand, provides sufficient information for calculating the position of the projected penetration points and the velocity vector of the incoming projectile. This system covers only a military application related to the calculation of an incoming projectile's position and velocity vector, wherein the trajectory is assumed to be linear. This reference relies upon making four successive time measurements. This reference does not address the determination of the path of an outgoing object, much Iess determining a projected trajectory calculated as a parabola corrected for aerodynamic drag. Furthermore, this patent application does not mention how to prevent the over saturation of the diode array when the image of the sun is focused on it.
[4015] There is a need for a sports training system fox tracking an object in space that does not xequire a semi-permanent installation, but can be set up and ready for use in a shoat time and within a limited space. Such a system can facilitate the training of baseball playexs, tennis players and players of other sports based upon control of a projectile. The device could also be used in the evaluation of the mechanical propexties of a baseball bat, golf club, tennis racket, ox other device used for striking an incoming projectile.
[0016] Imaging systems can form an image of an object on a planar surface, as in the case of a charge-coupled device, CCD, employed in a video camera. Such planar images require time to sample all of the pixels available in an x, y stray. Simpler imaging systems utilize a linear array that provides a far smaller number of. pixel sensors. The sampling time is accordingly substantially reduced. However, such known linear arrays can only sample a planar surface in space, viewed edge-on.
[0017] Such linear arrays can be provided with directed pixel sensors, aligned to divide the surface of the viewing plane into a discrete number of viewing sectors. Thus an 82.4-degree field of view divided amongst 512 directed pixel sensors will allow each directed sensor to detect an object present within a detection zone having an average angular dimension of 0.161 degrees within the detection plane.
[00183 While providing some image information with respect to the location of an object in space, the full location of an object, much less its firajectory, cannot be defined through use of a single linear array of directed pixel sensors. This invention addresses a method by which multiple linear arrays having directed pixel sensors rnay be utilized to obtain more information about the location of an object, and according to variants, defining not only its instantaneous location in space, but also its path of travel, local velocity and ultimate trajectory.
[0019] The invention in its general form will first be described, and then its implementation in terms of specific embodiments will be detailed with reference to the drawings following hereafter. These embodiments axe intended to demonstrate the principle of the invention, and the manner of its implementation. The invention in its broadest and more specific forms will then be further described, and defined, in each of the individual claims which conclude this Specification.
SUMMARY OF THE INVENTION
to [0020] According to the invention in a first variant, two linear detection optical sensor arrays, each having a plurality of directed pixel sensors, are positioned to provide overlapping fields of view in or substantially within a common, shared, planar field of view. By triangulation, the position of the object within the common field of view caa~
then be calculated.
I S Knowing the baseline between the two detection arrays and the angular orientation in space of the common field of view, the precise position in space of the object can be calculated and the time of its penetration of such field can be recorded.
[0021 ] The respective fields of view of the two linear detection arrays need not be precisely 24 co-planar. If such ,fields of view are sufficiently proximate to each other an object of finite length may simultaneously be detected in both fields. Furthermore, taking the hypothetical case of an infnitely small object, floe consecutive detection of the object by the first and second arrays over a very short interval can be taken, as an approximation, as being simultaneous. lxi either case, by treating the respective fields of view as ifthey were coplanar, the location of the 25 object in space can be calculated.
[0022] According to a feature of the invention, two linear detection arrays may be said to constitute a "set of arrays". By employing a pair of such sets, each set providing respective, shared, common fields of view, an accurate xzleasurement can be made of the position of the 30 tracked object at two locations. This can be used to establish the local trajectory or the line of travel of an object. In the case of a launched projectile, e.g. a golf ball, for which the takeoff point is known, the initial parabolic path of such projectile can be established without taking time measurements. Recording the time between the successive intersections of the object with the respective common fields of view allows the object's immediate velocity to be established.
35 This provides a further means for determining the initial parabolic path of a projectile.
[0023] When the object penetrates the f rst common field of view of the first set of position sensor arrays, a first set of coordinates, x-coordinate as and y-coordinate h is calculated by a data processor based on data provided by such sensors. The same sequence of events is repeated when the object enters the second planar field of view and a second set of coordinates is calculated. The path of travel is defined by these values, so obtained. The system described so far in the present varianfi does not requaxe any time measurement to calculate the object's initial path of flight.
[0024] If the take-off point is known and the object's local velocity is determined from the two sets of measured coordinates combined with the time delay between sightings, then the data can be combined to define a projected, extended, trajectory and an approximate landing point. This can be done by using an algorithm that incorporates known corrections for air resistance. This trajectory may be displayed in a video presentation andJor range and directional data can be provided to the player through some form of display.
Possible displays include visual displays and auditory displays amongst others [0025] The associated sensor arrays in each set that monitor a shared, common field of view must be separated from each other so that their respective fields of view intersect at an angle.
I3owever, two sensor arrays, each directed to monitoring a different field of view, may be mounted in a single, common support that fixes their angle of orientation to each other. Thus two pods, each containing two such angularly fixed arrays, array be zxzounted on either side of the object's flight path. This feature of mounting two angularly fixed arrays in each pod provides a fixed value for one of the parameters required for the analytic analysis, namely the angle between such arrays.
[0026] It is further necessary to know the orientations of the respective common fields of view. This may be achieved by mounting the arxays in an assembly which is provided with means for controlling the orientation and positions of the respective arrays, and thereby controlling the orientation and positions of their associated common fields of view.
[0027] While the invention has been described is applicable to golf, baseball, tennis training and the like, it can be usefully employed in any situation wherever there is a need to determine the location of an object, in space, its velocity and its trajectory. It is applicable to both incoming and outgoing objects. The invention is also applicable to tracking an incoming projectile aimed at a target, suclras-a velziclc.
[0028) In the case of a 'return" activity, wherein a projectile's trajectory is calculated in the incoming and outgoing directions, data can be obtained during both the incoming and outgoing IO phases of the path followed by a struck object and used to produce a combined output.
Examples of a situation in which this informarion would be invaluable are the training of a baseball, tennis, or cricket player, or the player of any sport in which a projectile is struck by a device. From this data, a display can be provided that indicates the e~ciency of the blow being struck that effects the return.
[0029] A further feature of the invention is that over-saturation of the photosensitive array due to excessive illumination, as by the sun, can be achieved by using photodiode arrays with an "anti-blooming" control as well as by the use of wave-length selective optical filters and/or photosensitive optical filtering that darkens when exposed to intense light, i.e., an auto-darkening, photochromic optical filter.
[0030] The foregoing sumrnarazes the principal features of the invention and some of its optional aspects. The invention may be further understood by the description of the preferred embodiments, in conjunction with the drawings, which now follow.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031) The figures accompanying this disclosure are summarized as follows:
[0032] Figure I is a pictorial schematic of the system of the invention applied to golf [0033] Figure 2 depicts a position sensor assembly in face view showing a single sensor axray.
[0034] Figure 3 depicts a set of two associated arrays whose fields of view overlap to provide a single position sensor zone.
[0035] Figure ~. illustrates the geometric principles for determination of the ball's coordinates within a single position sensor zone.
[0024] If the take-off point is known and the object's local velocity is determined from the two sets of measured coordinates combined with the time delay between sightings, then the data can be combined to define a projected, extended, trajectory and an approximate landing point. This can be done by using an algorithm that incorporates known corrections for air resistance. This trajectory may be displayed in a video presentation andJor range and directional data can be provided to the player through some form of display.
Possible displays include visual displays and auditory displays amongst others [0025] The associated sensor arrays in each set that monitor a shared, common field of view must be separated from each other so that their respective fields of view intersect at an angle.
I3owever, two sensor arrays, each directed to monitoring a different field of view, may be mounted in a single, common support that fixes their angle of orientation to each other. Thus two pods, each containing two such angularly fixed arrays, array be zxzounted on either side of the object's flight path. This feature of mounting two angularly fixed arrays in each pod provides a fixed value for one of the parameters required for the analytic analysis, namely the angle between such arrays.
[0026] It is further necessary to know the orientations of the respective common fields of view. This may be achieved by mounting the arxays in an assembly which is provided with means for controlling the orientation and positions of the respective arrays, and thereby controlling the orientation and positions of their associated common fields of view.
[0027] While the invention has been described is applicable to golf, baseball, tennis training and the like, it can be usefully employed in any situation wherever there is a need to determine the location of an object, in space, its velocity and its trajectory. It is applicable to both incoming and outgoing objects. The invention is also applicable to tracking an incoming projectile aimed at a target, suclras-a velziclc.
[0028) In the case of a 'return" activity, wherein a projectile's trajectory is calculated in the incoming and outgoing directions, data can be obtained during both the incoming and outgoing IO phases of the path followed by a struck object and used to produce a combined output.
Examples of a situation in which this informarion would be invaluable are the training of a baseball, tennis, or cricket player, or the player of any sport in which a projectile is struck by a device. From this data, a display can be provided that indicates the e~ciency of the blow being struck that effects the return.
[0029] A further feature of the invention is that over-saturation of the photosensitive array due to excessive illumination, as by the sun, can be achieved by using photodiode arrays with an "anti-blooming" control as well as by the use of wave-length selective optical filters and/or photosensitive optical filtering that darkens when exposed to intense light, i.e., an auto-darkening, photochromic optical filter.
[0030] The foregoing sumrnarazes the principal features of the invention and some of its optional aspects. The invention may be further understood by the description of the preferred embodiments, in conjunction with the drawings, which now follow.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031) The figures accompanying this disclosure are summarized as follows:
[0032] Figure I is a pictorial schematic of the system of the invention applied to golf [0033] Figure 2 depicts a position sensor assembly in face view showing a single sensor axray.
[0034] Figure 3 depicts a set of two associated arrays whose fields of view overlap to provide a single position sensor zone.
[0035] Figure ~. illustrates the geometric principles for determination of the ball's coordinates within a single position sensor zone.
__ . . ~u,. R m..ri . , ~,~ ~~~..~,.~~.~ ,~,w. . a . . .~ ~",d_a~~~ .~~..
___~.
S [0036] Figtare 5 is a schematic of a sensor pod with two sensor arrays mounted at a fixed angle to each other and inclined away from the viewer to be direoted towards a flight path.
[0037] Figure 6 shows the side view of the position sensor zones and of the strike zone plane in baseball for use in determining the accuracy of a pitched baseball.
IaESCRIPTION OF THE PREFERRED EMBODIMENT
[0038] Figure 1 illustrates the operation of the system as it tracks a golf ball 1. Two sensor pods 2, each containing two position sensor arrays 3, are installed with one pod 2 on either side of the target line 4 at a known separation distance. The "target Iine°' is 'the line over which the IS object to be sensed is expected to pass. The sensor pods 2 are connected electronically by a wire link 5 or a wireless link to the electronic processing unit 6. This unit sends signals to a display 7.
[0039] When the sensor pods 2 are aligned, the fields of view S generated by each of the respective position sensor arrays 3 in one sensor pod 2 preferably overlap with the fields of view of a corresponding position sensor array 3 in the other sensor pod. This defines two common planar position sensor zones A and B. The sensor arrays 3 which combine to define a sensor zone constitute an associated set of sensor arrays, with one membex of the set being present in each sensor pod 2.
[0040] As the golf ball 1 crosses these zones, the processor 10 in the electronic unit 6 receives the data as to the location of the object within each zone A, B and calculates by triangulation, using standard geometric analysis, the coordinates of the penetration points 9.
The electronic processor 10 also calculates the distance between such penetration or points and the ball's travel time between these points. Fxoxn this data, the processor IO
can determine the ball's velocity vector including the'speed of the ball 1, the take-off angle B
with respect to the horizontal plane, and the angular deviation of the flight path from the target line 4 in the horizontal plane. Using established ballistics data, the processor 10 can estimate the ball's projected trajectory and the range of the drive. Range calculations take into account aerodynamic effects acting on the ball 1 using known data and procedures.
'These calculations can include the use of previously generated tables based upon the known behaviour of objects such as golf balls.
[0041 ] A description of the system's components and operation follows.
[0042] Each sensor pod 2 contains a set of two position sensor arrays 3, as shown individually in Figure 2 and collectively in Figure S. Each position sensor array 3 consists of a linear array of photodiodes or a charge-coupled device (CCD) providing data inputs to a processor 10 in the electronic unit 9. A sensor array 3 in one pad 2 is paired with a senor array 3 in the other pod 2 to create a set of associated sensor arrays for ptxtposes of detecting an object present in their respective, shared, intersecting fields of view A, B, [0043] The photodiode array 3 may be equipped with an "anti-bloomitxg"
control, i.e. an operational feature that prevents over exposure of the diodes or the spill over of excessive charge from a pixel irradiated by the image of the sun to its neighbours on either side. This feature could be further enhanced by use of a wavelength selective band-pass filter 12 or a photochxomie, auto-darkening optical filter whose attenuation. increases when exposed to sunlight.
[0044) Known position sensor assemblies suitable for this application have characteristics similar to the device described as follows:
Lens characteristics . /1.8 Focal length . 3.8 mm Detector . linear photodiode array Number of diodes (pixels) . 512 (typically) Width oflinear array . 0.013 mm Diode pitch . 0.013 mm Length of array . 6.656 mm [0045] Each position sensor 3 has a fan-shaped field of view whose angular dimensions are 82.4 degrees by O.I96 degrees, consisting of 512 detection zones (see Figure 2). Each pixel detection zone 13 has angular dimensions of 0.161 ° (average) x 0.195°. The fields of view 8 of the position sensors in each assembly are aligned to intersect substantially within a common, shared planar field of view, designated as position sensor detection zones A
and B in Figure 1.
This allows an object within the comxnon, shared planar field of view to be located by a set of polar coordinates overlaid on the shared planar field of view in position sensor zones A and B ' {see Figure 3) as explained in the following description. The position sensors face the luminous sky and the target may appear either as a darker object against the lighter background, or as a lighter object against a darker background. In either case; its axrival causes a change in the intensity of tlxe light sensed by the respective sensor arrays 3.
[0045) When a ball 1. crosses position sensor zones A and B, its iixzage on the photodiode arrays 3 covers a certain nurxzber of pixels. As the processor in the electronic unit scans each a array 3, typically at a minimum rate of 2 kI3z, it identifies the ball's location in position sensor zone A arid B by the differential effects created by the presence of the ball I in the field of view 8.
[0047] The identification can be achieved by subtracting from each data bit stream of a scan the stored data bit stream of the preceding scan. Since the data of the background illumination remains the same during both scans, they are eliminated by this operation and the remaining singularity in the most recent frame is the image of the ball 1. The processor 10 in tlxe electronic unit 9 determines the center of this image which it uses as the location of the object. It then calculates from the viewing angles cz and r3, (Figure 4), the x-coordinate a, and y-coordinate h of the object from the following equations in respective each of the sensor zones A and B:
_ tan,8 a' Tatan/j+tany {1) _ tank tang a tan ~ -~- tan y {2) [004$] As an example, a golf ball (1.6$ in. = 4.22 cm diameter) at a distance or l.S rn subtends an angle of 1.51 ° and its image on the detector arxay can cover 10 to 11 pixels. It will be assumed that angles ~ and can be measured with an r.zn.s. error of two pixels; i.e. 0.322 °
. _.... "., m,x . . .., n ,, v~x...." , ,_.,._~~.~~~im .. ~ ~ ...... . "~M. __ ~__...,-~~.~,.~,.....___ _... __.._~.~_ ~_~_._._ __.___.~.~. _ _ .. .
~~~ur~.-"~~..
= 0.00562 rad.. The corresponding errors dal and dll can be calculated from the following equations:
~ ; ~ a~ a1~~2 +~ a er~2 (3) ( a z eh ~a~ ~Ij~ +Cay ~Y~
(4) Where:
Bat _ tan y a~3 y a eos2 ~3 (tan ~3 + tan y)2 (5) ~ _ _a tan ~'3 ay cosy y (tan/.3+tany~2 (6) ~h tans Y
a~ T a ~s2 ,B (tan ~3 + tan y)Z
f~) _ah tan2,Q _ =a 8y cosay (tan~3+tany)2 ($) For , = I 6.0°, = 63.4° and a =1.5 m the following r.m.s, errors were calculated:
ai=0.6 cm h =l.Ocm The velocity vector of the ball 1 can be determined from the coordinates of the penetration points 9 in position sensor zone A and B, and the flight time between them.
[0049] The calculation of penetration points 9 in position zones A and B is sufficient to I S determine the golf ball's trajectory. This data alone can be provided to a display to infornn a player as to the direction of travel of a struck ball 1. To provide a read-out of range, ~-ther data must be acquired. The projected trajectory of a struck object is a parabola that has to be corrected for aerodynamic drag. Equation {9) describes a parabola which intersects the x-axis at point x = 0, the known location for the commencement of the golf ball's trajectory.
This parabola also intersects the x-axis at x = rnln.
. Y - mx-- r~ f9) IO
Using different parameters, m = trxn8 n= G 12(vo'~cos B)a 1S where B is the take-off angle, G is the gravitational constant and va is the ball's take-off velocity.
[OOIO] The parabola can be defined if the parameters r~ and n are known. They can be calculated by substituting the coordinates 'of the two penetration points 9 into equation {9).
This operation results in two equations, which suffice to calculate the two unknowns m and 20 n and thereby define the parabolic trajectory. A parabolic path can be determined because the point of origin or take-off point for the golf ball 1 is also known.
Consequently, the trajectories of objects can be determined without measuring time so long as the distance along the target line 4 from the take-off point I4 to the base-line 2 5 is known.
25 [0450] If this distance is not known, it ncaay be approximated by projecting a line through the penetration points g of the object back from detection zones A and B to the horizontal plane. The resulting intersection point is close to the origin because the initial part of the parabolic path can be approximated by a straight line. The velacity determination, based on the delay between penetration of the two saane~zA:,-T-t-can-be-used-to calcuiate-tlie -- ~ w- --- w°' 30 parabolic path from which zange can thereafter be established.
jOQ51] If the distance to the take.-off point 14 is also known, calculations may be made using both methods and the results may be combined for unproved accuracy.
35 [DO52] The prajected trajectory can then be corrected for aerodynamic drag by using pre-calculated ballistic data that apply to a golf ball or baseball or the like. Such data is ,""."...."". .-...."...,. r,. ., .,.,.:.... ".,..
,..,.,r,r:ame..watctt..,.,."aa~y.,.earnw.:~mm~rnrsexww~c..ca..mv~Mnx..n~" .
°.pMC:.v-:.~m.~mc..,."u,w--.....~.....,......e.,..."...xr".,.~ww.~-v..ww.w.,.,."..;.,...vmw..,zn.~:... P.'3'~...saa.,...«s,"w-..~-..-...._.....~..,~,.....,....._. ......_ ~e.,r.
available from a number of sources and can be obtained in the case of a golf ball, for example, from P.W. $ehrman, 3.K. Harvey, Golf Ball Aerodynamics, Aeronautical Cluarterly, p. 112-122, IVlay 1976_ [0053] The foregoing has been directed to calculating future traj~tories. The past trajectory of an arriving object can also be calculated, again using ballistic analysis, to determine the origin of an object of a known type arriving under its oven momentum. This can have military applications, as where it is desired to determine the firing point of an incoming hostile ballistic projectile.
The system configuration described offers the following features:
~ Four fields of view are merged in two planes (detection zones A and B), simplifying the calculation burden.
~ 'The penetration paints in both zones and the distance between them can be calculated by simple triangulation, independently of tune.
~ The flight trajectory can be modeled as a parabolic trajectory corrected for aerodynamic drag without time measurements if the take-oi3F point is known, but time measurements can he taken into account to provide ari alternate calculation and increased accuracy.
, ~ To determine the velocity vector, two time measurements, as the ball crosses position sensor zones A and B, are required.
~ For a known object having known air resistance characteristics, a parabolic trajectory corrected for aerodynamic drag can then be calcuiated_ ~ The system is bi-directional, this means that it can measure all the above 3t) quantities regardless of flight direction, Ieft to right or right to left with respect to position sensor zones A and F.
~ Flight paths can be established for objects, both incoming and outgoing.
Description of a Sensor Pod 3S [0054] The sensor pod 2 is illustrated in Figure 5. It consists of a weatherproof housing 15 fitted with two windows 16 and a handle 17 pierced by an opening (not seen in Figure S). The housing 15 contains two position sensor arrays 3 mounted in two planes, typically at an angle of 45 degrees with respect to each other and angled sideways to address the flight path. This configuration produces overlapping fields of view whereby sets of associated arrays in each sensor pod define the position sensor zones A and B. This is illustrated in Figure 3.
j0055] An eaz~z anchorl mounting post 7 8, shown as a screw-threaded spike, supports the assembly. The mounting post ? 8 may be screwed into the ground by turning the handle 17.
The housing I5 can be rotated on this support and locked in position by a horizontal Lock 19 as part of the alignment procedure. The support 18 may be equipped with a level 20, such as a trapped air bubble, to ensure that the alignment takes place in a horizontal plane. The support may be mounted on a telescopic post with a vertical lock 21 allowing height adjustments where 7 5 this is required. otherwise, the units are installed on a horizontal surface.
[0056] The two sensor pods 2 are installed separated by a known distance apart This can be measured by using a wire or equivalent tether to serve as a base line 15.
Normally, the baseline would lie a short distance in front of the take-off point 14, infiersected approximately centrally by the target line 14 i.e, the horizontal projection of the target's path of flight. Data from the sensox pods 2 to the electronic unit 9 can be transmitted either over wire S or over a wireless link. In the former approach a section of the wire link from the left sensor pod 2 to the right sensor pod 2 (Figure 1) can be installed under or with the base line 15.
[0057) The two sensor pods 2 can be installed, as an example, either at a golf tee or in a space reserved for golf practice, or in front of a batter's position, in the following manner (Figure 1):
1. A typically 2-m long aluminum or plastic base line 1S is placed perpendicularly to the target line 4 over which an object is to pass.
2. The posts 1$ axe inserted vertically in the ground or other support surface at the ends of the base line 15 by turning the handle 17 and relying on the level 20 as a reference.
3. The sights 22, initially optionally folded in the handle 17, are then erected, and the sensor housings 15 are rotated until the sights 22 are aligned, The sensor housings are then locked in position by the horizontal lock 19. Tf vertical adjustments are necessary, they can be achieved by vertically displacing and locking the post's telescoping parts ....... , .. .........._~,."" ~::a'.~n~.T_y~,.,y-..R;,y;.:"gas.,""».;.,~..,.,~...,..,..-a..-_---.- . . ----.-..a.,.~~ .. .
......._ ...~..p.._._...
S with the vertical lock 21. The horizontal alignment should be checked after a vertical adjustment to ensure it has not been disturbed. In are alternate alignment procedure, small lasers mounted in the handle could replace the pop~up sights.
[0058] Fallawing this installation procedure, the wiring li:nlcs are effected and the electronic unit 9 is switched on. All the ensuing calculations are based on the distance between the sensor pods 2 determined by the base line 15, the distance from the take-off point 14 to the base-line (if required} and the angles of the detected projectile as measured by the position sensors 3. As soon as a ball 1 crosses position sensor zones A
and B, the electronic 9 unit can display the following data:
~ Speed, Take-off angle in the vertical plane, I3eviation from the target line in the horizontal plane, ~ Prnjected or hit range.
While it is well known that golf bails can curve significantly in flight, knowing a projected value for a been range can nevertheless provide a useful incentive for golfing practice.
'[0059j The systen~z can be used for golf or batting practice i~ a restricted space where a net catches the ball. It can also be installed at a tee or baseball diamond and display the above data to each player participating ixi the game, as well as to an audience. l;uch displays can include a video.depiction ofthe projected trajectory, in real time.
[0060] In baseball, sensor pods 2 can be installed so that the detection zones A,B lie in the path of the pitched ball 23, preferably in front of the home base on either side of the reference Line running through the centre of tlxe pitcher's circle and the centre of the home base circle. The electronic 9 unit can then calculate the speed of the ball 23 as well as its direction in the horizontal and vertical plane both after being thrown by the pitcher and after being hit by the batter. This information can be displayed on the electronic unit and.
recorded, to be reviewed by the coach, players and fans or posted instantaneously for all to view.
___~.
S [0036] Figtare 5 is a schematic of a sensor pod with two sensor arrays mounted at a fixed angle to each other and inclined away from the viewer to be direoted towards a flight path.
[0037] Figure 6 shows the side view of the position sensor zones and of the strike zone plane in baseball for use in determining the accuracy of a pitched baseball.
IaESCRIPTION OF THE PREFERRED EMBODIMENT
[0038] Figure 1 illustrates the operation of the system as it tracks a golf ball 1. Two sensor pods 2, each containing two position sensor arrays 3, are installed with one pod 2 on either side of the target line 4 at a known separation distance. The "target Iine°' is 'the line over which the IS object to be sensed is expected to pass. The sensor pods 2 are connected electronically by a wire link 5 or a wireless link to the electronic processing unit 6. This unit sends signals to a display 7.
[0039] When the sensor pods 2 are aligned, the fields of view S generated by each of the respective position sensor arrays 3 in one sensor pod 2 preferably overlap with the fields of view of a corresponding position sensor array 3 in the other sensor pod. This defines two common planar position sensor zones A and B. The sensor arrays 3 which combine to define a sensor zone constitute an associated set of sensor arrays, with one membex of the set being present in each sensor pod 2.
[0040] As the golf ball 1 crosses these zones, the processor 10 in the electronic unit 6 receives the data as to the location of the object within each zone A, B and calculates by triangulation, using standard geometric analysis, the coordinates of the penetration points 9.
The electronic processor 10 also calculates the distance between such penetration or points and the ball's travel time between these points. Fxoxn this data, the processor IO
can determine the ball's velocity vector including the'speed of the ball 1, the take-off angle B
with respect to the horizontal plane, and the angular deviation of the flight path from the target line 4 in the horizontal plane. Using established ballistics data, the processor 10 can estimate the ball's projected trajectory and the range of the drive. Range calculations take into account aerodynamic effects acting on the ball 1 using known data and procedures.
'These calculations can include the use of previously generated tables based upon the known behaviour of objects such as golf balls.
[0041 ] A description of the system's components and operation follows.
[0042] Each sensor pod 2 contains a set of two position sensor arrays 3, as shown individually in Figure 2 and collectively in Figure S. Each position sensor array 3 consists of a linear array of photodiodes or a charge-coupled device (CCD) providing data inputs to a processor 10 in the electronic unit 9. A sensor array 3 in one pad 2 is paired with a senor array 3 in the other pod 2 to create a set of associated sensor arrays for ptxtposes of detecting an object present in their respective, shared, intersecting fields of view A, B, [0043] The photodiode array 3 may be equipped with an "anti-bloomitxg"
control, i.e. an operational feature that prevents over exposure of the diodes or the spill over of excessive charge from a pixel irradiated by the image of the sun to its neighbours on either side. This feature could be further enhanced by use of a wavelength selective band-pass filter 12 or a photochxomie, auto-darkening optical filter whose attenuation. increases when exposed to sunlight.
[0044) Known position sensor assemblies suitable for this application have characteristics similar to the device described as follows:
Lens characteristics . /1.8 Focal length . 3.8 mm Detector . linear photodiode array Number of diodes (pixels) . 512 (typically) Width oflinear array . 0.013 mm Diode pitch . 0.013 mm Length of array . 6.656 mm [0045] Each position sensor 3 has a fan-shaped field of view whose angular dimensions are 82.4 degrees by O.I96 degrees, consisting of 512 detection zones (see Figure 2). Each pixel detection zone 13 has angular dimensions of 0.161 ° (average) x 0.195°. The fields of view 8 of the position sensors in each assembly are aligned to intersect substantially within a common, shared planar field of view, designated as position sensor detection zones A
and B in Figure 1.
This allows an object within the comxnon, shared planar field of view to be located by a set of polar coordinates overlaid on the shared planar field of view in position sensor zones A and B ' {see Figure 3) as explained in the following description. The position sensors face the luminous sky and the target may appear either as a darker object against the lighter background, or as a lighter object against a darker background. In either case; its axrival causes a change in the intensity of tlxe light sensed by the respective sensor arrays 3.
[0045) When a ball 1. crosses position sensor zones A and B, its iixzage on the photodiode arrays 3 covers a certain nurxzber of pixels. As the processor in the electronic unit scans each a array 3, typically at a minimum rate of 2 kI3z, it identifies the ball's location in position sensor zone A arid B by the differential effects created by the presence of the ball I in the field of view 8.
[0047] The identification can be achieved by subtracting from each data bit stream of a scan the stored data bit stream of the preceding scan. Since the data of the background illumination remains the same during both scans, they are eliminated by this operation and the remaining singularity in the most recent frame is the image of the ball 1. The processor 10 in tlxe electronic unit 9 determines the center of this image which it uses as the location of the object. It then calculates from the viewing angles cz and r3, (Figure 4), the x-coordinate a, and y-coordinate h of the object from the following equations in respective each of the sensor zones A and B:
_ tan,8 a' Tatan/j+tany {1) _ tank tang a tan ~ -~- tan y {2) [004$] As an example, a golf ball (1.6$ in. = 4.22 cm diameter) at a distance or l.S rn subtends an angle of 1.51 ° and its image on the detector arxay can cover 10 to 11 pixels. It will be assumed that angles ~ and can be measured with an r.zn.s. error of two pixels; i.e. 0.322 °
. _.... "., m,x . . .., n ,, v~x...." , ,_.,._~~.~~~im .. ~ ~ ...... . "~M. __ ~__...,-~~.~,.~,.....___ _... __.._~.~_ ~_~_._._ __.___.~.~. _ _ .. .
~~~ur~.-"~~..
= 0.00562 rad.. The corresponding errors dal and dll can be calculated from the following equations:
~ ; ~ a~ a1~~2 +~ a er~2 (3) ( a z eh ~a~ ~Ij~ +Cay ~Y~
(4) Where:
Bat _ tan y a~3 y a eos2 ~3 (tan ~3 + tan y)2 (5) ~ _ _a tan ~'3 ay cosy y (tan/.3+tany~2 (6) ~h tans Y
a~ T a ~s2 ,B (tan ~3 + tan y)Z
f~) _ah tan2,Q _ =a 8y cosay (tan~3+tany)2 ($) For , = I 6.0°, = 63.4° and a =1.5 m the following r.m.s, errors were calculated:
ai=0.6 cm h =l.Ocm The velocity vector of the ball 1 can be determined from the coordinates of the penetration points 9 in position sensor zone A and B, and the flight time between them.
[0049] The calculation of penetration points 9 in position zones A and B is sufficient to I S determine the golf ball's trajectory. This data alone can be provided to a display to infornn a player as to the direction of travel of a struck ball 1. To provide a read-out of range, ~-ther data must be acquired. The projected trajectory of a struck object is a parabola that has to be corrected for aerodynamic drag. Equation {9) describes a parabola which intersects the x-axis at point x = 0, the known location for the commencement of the golf ball's trajectory.
This parabola also intersects the x-axis at x = rnln.
. Y - mx-- r~ f9) IO
Using different parameters, m = trxn8 n= G 12(vo'~cos B)a 1S where B is the take-off angle, G is the gravitational constant and va is the ball's take-off velocity.
[OOIO] The parabola can be defined if the parameters r~ and n are known. They can be calculated by substituting the coordinates 'of the two penetration points 9 into equation {9).
This operation results in two equations, which suffice to calculate the two unknowns m and 20 n and thereby define the parabolic trajectory. A parabolic path can be determined because the point of origin or take-off point for the golf ball 1 is also known.
Consequently, the trajectories of objects can be determined without measuring time so long as the distance along the target line 4 from the take-off point I4 to the base-line 2 5 is known.
25 [0450] If this distance is not known, it ncaay be approximated by projecting a line through the penetration points g of the object back from detection zones A and B to the horizontal plane. The resulting intersection point is close to the origin because the initial part of the parabolic path can be approximated by a straight line. The velacity determination, based on the delay between penetration of the two saane~zA:,-T-t-can-be-used-to calcuiate-tlie -- ~ w- --- w°' 30 parabolic path from which zange can thereafter be established.
jOQ51] If the distance to the take.-off point 14 is also known, calculations may be made using both methods and the results may be combined for unproved accuracy.
35 [DO52] The prajected trajectory can then be corrected for aerodynamic drag by using pre-calculated ballistic data that apply to a golf ball or baseball or the like. Such data is ,""."...."". .-...."...,. r,. ., .,.,.:.... ".,..
,..,.,r,r:ame..watctt..,.,."aa~y.,.earnw.:~mm~rnrsexww~c..ca..mv~Mnx..n~" .
°.pMC:.v-:.~m.~mc..,."u,w--.....~.....,......e.,..."...xr".,.~ww.~-v..ww.w.,.,."..;.,...vmw..,zn.~:... P.'3'~...saa.,...«s,"w-..~-..-...._.....~..,~,.....,....._. ......_ ~e.,r.
available from a number of sources and can be obtained in the case of a golf ball, for example, from P.W. $ehrman, 3.K. Harvey, Golf Ball Aerodynamics, Aeronautical Cluarterly, p. 112-122, IVlay 1976_ [0053] The foregoing has been directed to calculating future traj~tories. The past trajectory of an arriving object can also be calculated, again using ballistic analysis, to determine the origin of an object of a known type arriving under its oven momentum. This can have military applications, as where it is desired to determine the firing point of an incoming hostile ballistic projectile.
The system configuration described offers the following features:
~ Four fields of view are merged in two planes (detection zones A and B), simplifying the calculation burden.
~ 'The penetration paints in both zones and the distance between them can be calculated by simple triangulation, independently of tune.
~ The flight trajectory can be modeled as a parabolic trajectory corrected for aerodynamic drag without time measurements if the take-oi3F point is known, but time measurements can he taken into account to provide ari alternate calculation and increased accuracy.
, ~ To determine the velocity vector, two time measurements, as the ball crosses position sensor zones A and B, are required.
~ For a known object having known air resistance characteristics, a parabolic trajectory corrected for aerodynamic drag can then be calcuiated_ ~ The system is bi-directional, this means that it can measure all the above 3t) quantities regardless of flight direction, Ieft to right or right to left with respect to position sensor zones A and F.
~ Flight paths can be established for objects, both incoming and outgoing.
Description of a Sensor Pod 3S [0054] The sensor pod 2 is illustrated in Figure 5. It consists of a weatherproof housing 15 fitted with two windows 16 and a handle 17 pierced by an opening (not seen in Figure S). The housing 15 contains two position sensor arrays 3 mounted in two planes, typically at an angle of 45 degrees with respect to each other and angled sideways to address the flight path. This configuration produces overlapping fields of view whereby sets of associated arrays in each sensor pod define the position sensor zones A and B. This is illustrated in Figure 3.
j0055] An eaz~z anchorl mounting post 7 8, shown as a screw-threaded spike, supports the assembly. The mounting post ? 8 may be screwed into the ground by turning the handle 17.
The housing I5 can be rotated on this support and locked in position by a horizontal Lock 19 as part of the alignment procedure. The support 18 may be equipped with a level 20, such as a trapped air bubble, to ensure that the alignment takes place in a horizontal plane. The support may be mounted on a telescopic post with a vertical lock 21 allowing height adjustments where 7 5 this is required. otherwise, the units are installed on a horizontal surface.
[0056] The two sensor pods 2 are installed separated by a known distance apart This can be measured by using a wire or equivalent tether to serve as a base line 15.
Normally, the baseline would lie a short distance in front of the take-off point 14, infiersected approximately centrally by the target line 14 i.e, the horizontal projection of the target's path of flight. Data from the sensox pods 2 to the electronic unit 9 can be transmitted either over wire S or over a wireless link. In the former approach a section of the wire link from the left sensor pod 2 to the right sensor pod 2 (Figure 1) can be installed under or with the base line 15.
[0057) The two sensor pods 2 can be installed, as an example, either at a golf tee or in a space reserved for golf practice, or in front of a batter's position, in the following manner (Figure 1):
1. A typically 2-m long aluminum or plastic base line 1S is placed perpendicularly to the target line 4 over which an object is to pass.
2. The posts 1$ axe inserted vertically in the ground or other support surface at the ends of the base line 15 by turning the handle 17 and relying on the level 20 as a reference.
3. The sights 22, initially optionally folded in the handle 17, are then erected, and the sensor housings 15 are rotated until the sights 22 are aligned, The sensor housings are then locked in position by the horizontal lock 19. Tf vertical adjustments are necessary, they can be achieved by vertically displacing and locking the post's telescoping parts ....... , .. .........._~,."" ~::a'.~n~.T_y~,.,y-..R;,y;.:"gas.,""».;.,~..,.,~...,..,..-a..-_---.- . . ----.-..a.,.~~ .. .
......._ ...~..p.._._...
S with the vertical lock 21. The horizontal alignment should be checked after a vertical adjustment to ensure it has not been disturbed. In are alternate alignment procedure, small lasers mounted in the handle could replace the pop~up sights.
[0058] Fallawing this installation procedure, the wiring li:nlcs are effected and the electronic unit 9 is switched on. All the ensuing calculations are based on the distance between the sensor pods 2 determined by the base line 15, the distance from the take-off point 14 to the base-line (if required} and the angles of the detected projectile as measured by the position sensors 3. As soon as a ball 1 crosses position sensor zones A
and B, the electronic 9 unit can display the following data:
~ Speed, Take-off angle in the vertical plane, I3eviation from the target line in the horizontal plane, ~ Prnjected or hit range.
While it is well known that golf bails can curve significantly in flight, knowing a projected value for a been range can nevertheless provide a useful incentive for golfing practice.
'[0059j The systen~z can be used for golf or batting practice i~ a restricted space where a net catches the ball. It can also be installed at a tee or baseball diamond and display the above data to each player participating ixi the game, as well as to an audience. l;uch displays can include a video.depiction ofthe projected trajectory, in real time.
[0060] In baseball, sensor pods 2 can be installed so that the detection zones A,B lie in the path of the pitched ball 23, preferably in front of the home base on either side of the reference Line running through the centre of tlxe pitcher's circle and the centre of the home base circle. The electronic 9 unit can then calculate the speed of the ball 23 as well as its direction in the horizontal and vertical plane both after being thrown by the pitcher and after being hit by the batter. This information can be displayed on the electronic unit and.
recorded, to be reviewed by the coach, players and fans or posted instantaneously for all to view.
[0061 j Under controlled conditions, the system can be used to evaluate the mechanical characteristics of a bat, racket or the like by comparing the momentum of the pitched ball to the momentum of the ball after being struck. The display can include a presentation of the ratio of the outgoing speed to the incoming speed. It can also depict the direction of the struck ball, both vertically and horizontally.
[0052] Furthermore, the system zxxay be used to train a pitcher by creating in space an optronic strike zone 25, whose width is equal to that of the front rim of the home plate (17 in.) and whose height is equal to the distance between a hypothetical or real batter's shoulder and knees (approximately 3.5 ft). In an actual game, the stake zone 25 would have to be adjusted to x 5 accommodate each batter. For training pitchers, a standard, fixed strike zone can be provided.
[0063] The corners of the rectangle of the strike zone are defined by coordinates in a vertical plane to which correspond values of al and h in position sensor zone A. The latter sensor zone A is inclined at an angle of 22.5 degrees with respect to the vertical, as shown in Figure 6. Iu the conversion from al and h coordinates in position sensor zone A to the x,y coordinates in the plane of the strike zone, al remains the same while h has to be multiplied by cos 22.5° = U.924. When a baseball 23 crosses position sensor zone A, its coordinates are calculated, converted to the coordinates in the plane of the strike zone 25 and compared to the comer coordinates of the latter. While the center of the ball 23 is initially tracked, allowances for the width of the ball can be made. This sequence of mathematical operations establishes whether or not the baseball 23, or a portion of the baseball 23, has crossed through the strike zone 25. Observers can then be informed of the positive or negative outcome of this event on an alphanumeric or other display means.
j0064] In this scenario, the system plays the role of an electronic umpire.
The training can be rendered more realistic by installing dummies made of elastic material to serve as a simulated batter and a catcher at the home base. The realism of the training practice can be further enhanced by placing at Ieast one additional set of two, of sensor arrays, or preferably a further pair of pods 2, one on either side of the center line extending between the pitcher's circle and the home base circle. In this configuration the systems can track a curve ball and display the top view of its trajectory relative to the strike zone 25 on a video screen.
[0052] Furthermore, the system zxxay be used to train a pitcher by creating in space an optronic strike zone 25, whose width is equal to that of the front rim of the home plate (17 in.) and whose height is equal to the distance between a hypothetical or real batter's shoulder and knees (approximately 3.5 ft). In an actual game, the stake zone 25 would have to be adjusted to x 5 accommodate each batter. For training pitchers, a standard, fixed strike zone can be provided.
[0063] The corners of the rectangle of the strike zone are defined by coordinates in a vertical plane to which correspond values of al and h in position sensor zone A. The latter sensor zone A is inclined at an angle of 22.5 degrees with respect to the vertical, as shown in Figure 6. Iu the conversion from al and h coordinates in position sensor zone A to the x,y coordinates in the plane of the strike zone, al remains the same while h has to be multiplied by cos 22.5° = U.924. When a baseball 23 crosses position sensor zone A, its coordinates are calculated, converted to the coordinates in the plane of the strike zone 25 and compared to the comer coordinates of the latter. While the center of the ball 23 is initially tracked, allowances for the width of the ball can be made. This sequence of mathematical operations establishes whether or not the baseball 23, or a portion of the baseball 23, has crossed through the strike zone 25. Observers can then be informed of the positive or negative outcome of this event on an alphanumeric or other display means.
j0064] In this scenario, the system plays the role of an electronic umpire.
The training can be rendered more realistic by installing dummies made of elastic material to serve as a simulated batter and a catcher at the home base. The realism of the training practice can be further enhanced by placing at Ieast one additional set of two, of sensor arrays, or preferably a further pair of pods 2, one on either side of the center line extending between the pitcher's circle and the home base circle. In this configuration the systems can track a curve ball and display the top view of its trajectory relative to the strike zone 25 on a video screen.
(0065] The foregoing has constituted a description of specific embodiments showfng how the invention may be applied and put into use. These embodiments are only exemplary.
The invention in its broadest and more specific aspects is fiu~ther described and defined in the claims which now follow.
X0066] These claims, and the language used therein, are to be understood in terms of the variants of the invention which have been described. They are not to be restricted to such variants, but are to be read as covering the full scope of the invention as is implicit within the invention and the disclosure that has been provided herein.
The invention in its broadest and more specific aspects is fiu~ther described and defined in the claims which now follow.
X0066] These claims, and the language used therein, are to be understood in terms of the variants of the invention which have been described. They are not to be restricted to such variants, but are to be read as covering the full scope of the invention as is implicit within the invention and the disclosure that has been provided herein.
Claims (16)
1. A system for locating and tracking an object traveling in space comprising:
a) first and second sets of two linear detection sensor arrays, each set of two sensor arrays being separated by a known baseline;
b) sensor arrays within each set having a plurality of directed pixel sensors positioned to provide individual pixel fields of view which collectively provide a planar field of view for such sensor array;
c) the sensor arrays being mounted so that the individual fields of view of each member of a set of sensor arrays substantially overlap with each other in, or substantially within, a shared, substantially common field of view for each such set, the common field of view having a known angle of inclination;
d) the member arrays of the first set of two sensor arrays being mounted to position their common field of view at a known angle of orientation with respect to the common field of view of the second set of two sensor arrays;
e) electronic processing means connected to receive signals from said sensor arrays for calculating the positions of an object as it passes through the respective common fields of view to thereby determine the local path in space of the object as it passes through the respective, common fields of view; and f) display means connected to the processing by means to provide a display based upon such path.
a) first and second sets of two linear detection sensor arrays, each set of two sensor arrays being separated by a known baseline;
b) sensor arrays within each set having a plurality of directed pixel sensors positioned to provide individual pixel fields of view which collectively provide a planar field of view for such sensor array;
c) the sensor arrays being mounted so that the individual fields of view of each member of a set of sensor arrays substantially overlap with each other in, or substantially within, a shared, substantially common field of view for each such set, the common field of view having a known angle of inclination;
d) the member arrays of the first set of two sensor arrays being mounted to position their common field of view at a known angle of orientation with respect to the common field of view of the second set of two sensor arrays;
e) electronic processing means connected to receive signals from said sensor arrays for calculating the positions of an object as it passes through the respective common fields of view to thereby determine the local path in space of the object as it passes through the respective, common fields of view; and f) display means connected to the processing by means to provide a display based upon such path.
2. A system as in claim 1 wherein said electronic processing means includes means to record the times at which the object passes through the respective, common fields of view and, using the delay between the passage of the object through the respective common, fields of view, to calculate the velocity of said object as it passes between the respective common fields of view, and further comprising display means connected to the electronic processing means to provide a display based upon such calculated velocity.
3. A system as in claim 2 wherein said electronic processing means comprises ballistics processing means to provide a projected future path in space of the object as a projected future trajectory.
4. A system as in claim 2 wherein said electronic processing means comprises ballistics processing means to project the path in space of the object into the past as a projected past trajectory.
5. A system as is claim 1 wherein said electronic processing means determines the path of the object consecutively when the object traverses both common fields of view, traveling in both directions, both incoming and outgoing.
6. A system as is claim 2 wherein said electronic processing, means determines the path and speed of the object consecutively when the object traverses both common fields of view, traveling in both directions, both incoming and outgoing.
7. A system as in claim 5 wherein said display means provides a display based upon the path of the object as it traverses both common fields of view, traveling in both directions, both incoming and outgoing.
8. A system as in claim 6 wherein said display means provides a display based upon the velocity of the object as it traverses both common fields of view, traveling in both directions, both incoming and outgoing.
9. A system as in claim 8 wherein the display based on the velocity of the object includes a display corresponding to the relative incoming and outgoing velocities of the object.
10. The system as in claim 1 wherein the members of the respective first and second sets of sensor arrays are respectively installed in a pair of pods, each pod containing one member of each set of sensor arrays, such members in each pods being fixed to provide respective fields of view that are oriented at a known angle to each other.
11. The system of claim 10 comprising mounting means whereby each such pod may be installed on a support surface with the fields of view of the sensor arrays contained therein positioned at fixed, known orientations with respect to the support surface.
12. The system as in claim 10 wherein said pair of pods are installed at a space separation from each other at a golf tee.
13. The system as in claim 10 wherein said pair of pods are installed in front of a baseball home plate at a spaced separation from each other on either side of the line joining the pitcher's mound to home plate.
14. The system as in claim 5 wherein the members of the respective first and second sets of sensor arrays are respectively installed in a pair of pods, each pod containing one member of each set of sensor arrays, each pod being fitted with mounting means whereby such pod may be installed on the ground and wherein said pair of pods are installed in front of a baseball home plate at a spaced separation from each other on either side of the line joining the pitcher's mound to home plate.
15. The system of claim 1 comprising optical filter means positioned to filter light arriving from the field of view of each sensor array, said optical filter means being an auto-darkening optical filter.
16. The system of claim 1 comprising optical filter means positioned to filter light arriving from the field of view of each sensor array, said optical filter means being a selective wave-length optical filter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA2484674A CA2484674C (en) | 2003-10-15 | 2004-10-14 | Method and apparatus for locating the trajectory of an object in motion |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA2,244,464 | 2003-10-15 | ||
| CA002444464A CA2444464A1 (en) | 2003-10-15 | 2003-10-15 | Method and aparatus for locating the trajectory of a projectile in motion |
| CA2484674A CA2484674C (en) | 2003-10-15 | 2004-10-14 | Method and apparatus for locating the trajectory of an object in motion |
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| Publication Number | Publication Date |
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| CA2484674A1 true CA2484674A1 (en) | 2005-04-15 |
| CA2484674C CA2484674C (en) | 2013-04-02 |
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| CA2484674A Expired - Lifetime CA2484674C (en) | 2003-10-15 | 2004-10-14 | Method and apparatus for locating the trajectory of an object in motion |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110472181A (en) * | 2019-06-27 | 2019-11-19 | 南京市公安局鼓楼分局 | Round bullet impact and the case suspect of the window at the inclined angle in ground check method |
| CN110472179A (en) * | 2019-06-27 | 2019-11-19 | 南京市公安局鼓楼分局 | Round bullet impact and the case suspect of the perpendicular window in ground check method |
| CN110472185A (en) * | 2019-06-27 | 2019-11-19 | 南京市公安局鼓楼分局 | The ballistic trajectory calculation method of round bullet impact and the window at the inclined angle in ground |
| CN110472180A (en) * | 2019-06-27 | 2019-11-19 | 南京市公安局鼓楼分局 | The ballistic trajectory calculation method of round bullet impact and the perpendicular window in ground |
-
2004
- 2004-10-14 CA CA2484674A patent/CA2484674C/en not_active Expired - Lifetime
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110472181A (en) * | 2019-06-27 | 2019-11-19 | 南京市公安局鼓楼分局 | Round bullet impact and the case suspect of the window at the inclined angle in ground check method |
| CN110472179A (en) * | 2019-06-27 | 2019-11-19 | 南京市公安局鼓楼分局 | Round bullet impact and the case suspect of the perpendicular window in ground check method |
| CN110472185A (en) * | 2019-06-27 | 2019-11-19 | 南京市公安局鼓楼分局 | The ballistic trajectory calculation method of round bullet impact and the window at the inclined angle in ground |
| CN110472180A (en) * | 2019-06-27 | 2019-11-19 | 南京市公安局鼓楼分局 | The ballistic trajectory calculation method of round bullet impact and the perpendicular window in ground |
| CN110472185B (en) * | 2019-06-27 | 2023-07-18 | 南京市公安局鼓楼分局 | Method for calculating trajectory of window with inclination angle between round projectile impact and ground |
| CN110472179B (en) * | 2019-06-27 | 2023-07-18 | 南京市公安局鼓楼分局 | Case suspicion checking method for round shot hitting window perpendicular to ground |
| CN110472181B (en) * | 2019-06-27 | 2023-07-18 | 南京市公安局鼓楼分局 | Case suspicion checking method for round shot striking window with inclination angle with ground |
| CN110472180B (en) * | 2019-06-27 | 2023-07-21 | 南京市公安局鼓楼分局 | Method for calculating trajectory of round projectile striking window perpendicular to ground |
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| Publication number | Publication date |
|---|---|
| CA2484674C (en) | 2013-04-02 |
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