Description A SWING DIAGNOSIS DEVICE FOR USE IN BALL GAME SPORTS Technical Field
[1] The present invention relates to a diagnosis device for swing motion in ball game sports, specifically to a diagnosis device utilizing a motion sensor for swing motion in ball game sports wherein a stick is used to hit a ball, more specifically to a diagnosis device using micro electro mechanical system("MEMS") technology for golf swing. Background Art
[2] Some of ball game sports such as baseball, ping-pong, tennis and golf are using a bat, a racket or a club to hit a ball, which are all sticks. Proper angle, proper point and proper strength of impact and exact swing path are required for greater distance or desired direction of a flying hit ball. Impact accuracy including impact angle and impact point, impact strength and a swing path are the most important factors in ball game sports particularly when a stick is used to hit a ball in a game. The present invention describes mainly about golf, but it can be applied to other ball game sports.
[3] Golf swing is classified into putting by a putter, pitching by a short club such as an iron and driving by a relatively longer club such as a driver. Swing pattern differs according to a golf club, but the basic points of swing are square impact and tangential swing path to an aiming direction. With a swing so qualified, a player can send a ball a long distance in the right direction. A lot of tools to correct improper golf swing have been devised and some of them are being used. Such tools are using assistant devices to help a player to understand a principle of golf swing and to apply it to a real swing. However, there are few tools to check actual swing and to correct a bad swing in situ. There have been an analytical methods for motion images of golf swing. Two- dimensional motion images are obtained by a video projector working at high speed like a camcorder and a series of instant images acquired by time sharing of the motion image are compared with a standard swing pattern and is diagnosed with a professional's help. This method is complicated and expensive with costly equipments, software and a professional's help to interpret the images.
[4] Korean laying-open publication No. 2004-18570 disclosed a golf club, which can display a speed of a club head on it using a speed sensor. But this device can display the highest speed only during a swing. It is not helpful for diagnosis of swing pattern. Disclosure of Invention Technical Problem
[5] A purpose of the present invention is to provide a diagnosis device for swing
motion which acquires, analyzes and displays swing pattern and impact information using micro electro mechanical system(MEMS) for ball game sports. [6] Another purpose of the present invention is to provide a diagnosis device for swing motion using micro electro mechanical system(MEMS) for ball game sports wherein a stick is used to hit a ball. [7] Another purpose of the present invention is to provide a diagnosis device for golf swing to be used in an actual or similar situation. Technical Solution
[8] The present invention provides a diagnosis device for golf swing motion using Micro Electro-Mechanical System(MEMS) technology. The device comprises a sensor module, inserted or attached in a body or clothes or a stick, having at least one gyroscope, if necessary at least one accelerometer, if necessary at least one direction magnetometer and at least one signal processing circuit which converts analog signals sensed to digital signals; a power supply means; a wireless or wired communication means which pass the digital signals; a computing means to obtain swing motion information and to calculate the differences between the swing motion information and a reference swing pattern by applying a software routine to the digital signals passed via the communication means; and a display means interconnected to the computing means, "gyroscope", "down swing" and "back swing" are used instead of "gyro sensor", "forward swing" and "take back" respectively in this description. The gyroscope( or gyro sensor) used in this invention is not limited to a special type if miniaturization is possible. Three types of gyroscopes, for example, can be adopted in the present invention. First one is a mechanical gyroscope by the principle of gyro moment (gyro effect). Second is a vibration type gyroscope based on Coriolis acceleration of a vibrating body. The third one is an optical gyroscope using a phase difference between short wavelengths of laser.
[9] A mechanical gyroscope, as known, detects a displacement of a spring connecting a revolving body to an outer casing. The displacement is caused by a gyro moment that is generated when the body revolving around x axis at angular velocity w rotates around y axis at angular velocity Ω. The gyro moment is proportional to rotational angular velocity Ω.
[10] A vibration type gyroscope consists of a vibrating body, an outer casing, a spring connecting the vibrating body to the outer casing and a mechanical- electrical energy transforming element. The principle of this type is to measure a displacement of the spring caused by Coriolis acceleration force which acts when the outer casing rotates at angularr velocity Ω around y axis during the body vibrates in x axis direction. The Coriolis acceleration force is proportional to the mass of the vibrating body and
rotational angular velocity of the outer casing. This type is made smaller and cheaper by semiconductor manufacturing technology. A multi-axis gyro sensor also may be integrated in a package.
[11] Any accelerometer or any directional sensor made by micro electro mechanical system(MEMS) technology also can be basically used in the present invention as long as it can be miniaturized.
[12] In brief, the accelerometer used in the present invention consists of a rigid body, an outer casing, a spring connecting a rigid body to the outer casing and a mechanical- electrical energy transforming element. For example, a servo type and a silicon type may be used in the present invention. A servo type accelerometer as mechanical type measures a change of magnetic field when a body moves by acceleration. Silicon type accelerometers, which are small, light and cheap, have good mechanical properties and excellent reliability and productivity by established semiconductor manufacturing technology. Silicon accelerometers have also two types. One is piezo-resistive type made by thin film processing and bulk micro machining of single crystal silicon. The other is a capacitive type, which is made by surface micro machining of poly-silicon. This silicon accelerometer can measure two-dimensional or three-dimensional acceleration depending its structure.
[13] The direction magnetometer in the present invention is a magnetic sensor that measures magnetic field of earth, and thus absolute azimuth angle. It also may be used as a basis to obtain a bearing angle by gyroscope, because only a relative angle can be obtained by integration of the angular velocity detected by a gyroscope. A flux gate sensor as a direction magnetometer is used at normal temperature, which comprises an exciting coil wound around a soft magnetic core. It makes use of non-linear and saturation characteristics of a soft magnetic core. If magnetic field occurs by supplying alternating current big enough to an exciting coil, a flux density inside core saturates periodically, then the pick-up coil measures strength of the outer magnetic field by detecting a change of the magnetic flux density inside the core in the outer magnetic field.
[14] As known in the field, the signal processing circuit in the present invention, which converts analog signals to digital signals, consists of an analog to digital converter having same number of input-output channels and low pass filters as that of sensors. An analog to digital converter having an input-output channel may be used if a multiplexer is provided at the output terminal of a sensor.
[15] The display means includes not only screen display means but also speaker means and lighting means. The display means is, for example, LED, LCD, graphic LCD, a speaker or a buzzer. When the display means is a speaker or a buzzer, it can notice a player of a proper tempo modeling a standard swing pattern by sound, for example, a
series of beeps.
[16] In a preferred embodiment of the present invention, a wireless communication chip for a short distance, for example, a Rfid chip, a Bluthooth chip or a ZigBee chip as a part of communication means at the side of a sensor module can be integrated into a sensor module, and the other part of the communication means to receive sensor signal data, the said computing means and the display means can be integrated into a diagnostic module. The power supply means is desirably integrated into the sensor module and/or the diagnostic module. A wireless communication chips mentioned above can be manufactured, small and cheap. A Blue-Tooth chip, for example, consisting of a transreiver, a baseband and flash Roms is made one chip through integration.
[17] As another embodiment of the present invention, said sensor module can be attached to or inserted on the head of golf club or a golfer's body or clothes, and said diagnostic module is made as a separate assembly or inserted into a grip.
[18] As another embodiment of the present invention, said sensor module and said diagnostic module are monolithically mounted on the head of a golf club or in the shaft of a golf club or a golfer's body. When said sensor module or said diagnostic module is mounted on the head of a golf club, an impact shock may be relieved by insertion of a graphite sheet or a rubber sheet beneath the modules. A putter is more desirable for mounting modules on the head because it is used under relatively milder conditions.
[19] In a diagnosis device for golf swing according to the present invention the computing means by the software routine obtains at least one value of angular velocity, if necessary acceleration, if necessary bearing angle and if necessary at least one of their integration regarding the head of a golf club at one or more predetermined points during a swing consisting of back swing, down swing and follow swing; compares, if necessary, the value obtained with one or more values of a standard swing pattern chosen; decides, if necessary, whether said back swing, said down swing and/or said follow swing of said swing is within a predetermined range ; and display the results on a display means.
[20] As another embodiment of the present invention, said sensor module has at least one accelerometer, and said computing means obtain inclination angle of the ground while said head of said golf club is at rest on the ground.
[21] As another embodiment of the present invention, in diagnosis procedure, the computing means controls said diagnosis device by at least one value regarding at least one angular velocity and if necessary at least one acceleration. For selection of modes including powering, menu selection and scene shift in diagnosis procedure, the computing means controls said diagnosis device.
[22] To express a golf swing motion in 3 dimensions, a target line extending from a ball
to the target on the ground is assumed as x-axis. If the axis perpendicular to x-axis on the ground is z-axis, the axis vertical to the ground would be y-axis. By coordination transformation and integration of angular velocity values obtained from gyroscopes for 3 axes and acceleration value obtained from accelerometers for 3 axes during a swing cycle from aiming to follow through, a swing path can be calulated as follows.
[23] If Ωx, Ωy, Ωz is a rotation angle respectively for x, y, z axis
[24] θx = ∑ Ωx * ΔT
[25] θy = ∑ Ωy * ΔT
[26] θz = ∑ Ωz * ΔT
[27] If "x, "y, "z is acceleration respectively for x, y, z axis
[28] gx = "rcos# „ — ( "<? — 7 r r5 v) sin # [29] gy = "y — gsin 0 _
[31] vx, vy, vz speed for x, y, z axis are as follow.
[32] vx = ∑ gx * ΔT
[33] vy = ∑ gy * ΔT
[34] vz = ∑ gz * ΔT
[35] Location of a sensor module is as follows
[36] px = ∑ vx * ΔT
[37] py = ∑ vy * ΔT
[38] pz = ∑ vz * ΔT
[39] With the values mentioned above and a direction value detected by direction magnetometers, behaviors of a golf head can be completely grasped on the standpoint of theories. However, simplication for the general equation works well for real purpose. As another embodiment of the present invention, said computing means obtains at least one angular velocity value Ωy of gyroscope on x-z and/or at least one angular velocity value Ωz of gyroscope in x-y plane at least one or more points in the neighborhood of an impact of a swing and compares said value with a predetermined value(s). Said golf club is desirably a putter.
[40] The basic points of swing in golf are a square impact and a flat swing path. In case of a square impact, a club face at impact is perpendicular to a target line, which extends from the ball to a target. A flat swing path means a swing path of a club head tangential to the target line. In an exact flat swing path, the angle between a swing path of a club head and a target line(" incidence angle") before impact should be the same as
that after impact. Accordingly, diagnosis of swing form is possible by measuring the incidence angle and the reflection angle near impact point. Herein, we assume that the reflection angle would have plus(+) value when a swing path does not surpass a target line after impact, which is in case of a flat swing. If it does surpass a target line after impact, the reflection angle would have minus(-) value.
[41] 'Square impact' and 'flat swing path' mentioned above is considered only on the ground plane, i.e. x-z plane. On other than x-z plane the basic rule is not applied. For example, on x-y plane vertical to the target line, square impact is not desirable any more. As known in physics, a club face should have proper loft for a long flight of a ball, and thus square impact does not occur and is not desirable either. The initial speed of a hit ball is determined by face angle and club head speed. A ball with 45 flight angle flies father at the same initial speed. On that plane, a stepwise loft depending clubs is deliberately given to a club face . Flat swing path is not recommended either. As known, while plus incidence angle before impact is desirable, the reflection angle after impact point is recommended to be a little minus ("down blow") especially for a shorter club. However, negative incidence angle before impact and positive reflection angle after impact is recommended which is called "upper blow" for a driver.
[42] Golf swing motion in 3 dimensions can be analyzed for various planes. Generally, on the ground plane, i.e. x-z plane, the less are both of the incidence angle and the reflection angle while the two angles are almost the same, the more exact is the swing form. In other words, as angular velocity along y- axis of a club head during swing approaches 0 near an impact, the swing is more desirable. If angular velocity along y- axis goes over an acceptable level before and after impact point the swing may be regarded as having problems. Especially, very small incidence and reflection angles and also angular velocity along z- axis near an impact are required for putting.
[43] In another aspect, as another embodiment of the present invention, said computing means obtains at least one angular velocity value Ωx of a gyroscope on y-z plane at one or more points during a swing and compares said value with a predetermined value. This embodiment is proper for all kinds of clubs. Theories say that back swing, down swing and follow swing of a swing should be on the same plane when viewed from a target line, which means that a swing path including back swing should be in a straight line, i.e., 0 angular velocity on y-z plane.
[44] On those bases, analyzed information about a swing including angular velocities, bearing angles and time interval at various stages of a swing can explain how is the swing when compared with a standard swing. Those theories and principles mentioned before about a swing are examplified to describe the basic concept of the present invention. It is not insisted that those theories should be right always. The present invention may be applied to any kind of a golf club, short or long, but criteria are
different depending a club. A diagnosis device according to the present invention is also useful to improving swing skill beyond a basic rule. A player can deliberately make a hook ball or a slice ball other than a straight ball in hitting a ball to a target area. On this occasion, a swing can be diagnosed by comparing based on a theory other than "square impact" and "flat swing path" . Different theories or
[45] principles can be applied to the present invention as long as information of angular velocities, acceleration, bearing angles and also time interval in 3 dimensions are utilized at various stages of a swing.
[46] To illustrate the present invention described herein, to which an artisan will be able to add on many others, preferred examples of embodiments are described below, accompanied by non-scale schematic drawings. It is understood that, being those only examples, those do not limit the scope of the protection of the present invention, but those simply intend to explain and illustrate the basic principle on which those are based, Brief Description of the Drawings
[47] FIG 1 is a schematic perspective view illustrating an embodiment of a sensor module according to the present invention. [48] FIG 2 is a schematic perspective view illustrating another embodiment of a sensor module according to the present invention. [49] FIG 3 is a schematic perspective view illustrating a golf club mounted with the sensor module of FIG 2 and its partial cross sectional view. [50] FIG 4 is a schematic perspective view illustrating an embodiment of a diagnostic module having a flat panel display for a golf club according to the present invention. [51] FIG 5 is a partial cross sectional view illustrating a swing diagnosis device for a putter equipped monolithically with a sensor module and a diagnostic module as an another embodyment according to the present invention. [52] FIG 6 is a block diagram explaining the operation of the sensor module illustrated in FIG 3 and the diagnostic module illustrated in FIG 4 [53] FIG 7 is a block diagram explaining the operation of a diagnosis device illustrated in FIG 5 [54] FIG 8 is a perspective view illustrating a diagnostic module installed in the grip for a putter. [55] FIG 9, FIG 10, FIG 11, FIG 12 and FIG 13 are examplar graphs of amplitude on time axis of sensor signals [56] FIG 14 is a path graph of a swing of a putter on x-z plane
[57] FIG 15 is a swing path graph of a swing of a putter on x-y plane
[58] FIG 16 is a screen indicating incline level of the club head on the ground on x-z
plane
[59] FIG 17 shows a block diagram of an embodiment wherein signals for three gyroscopes for 3 axes (11a, 1 lb, 1 lc) and three accelerometers for 3 axes are delivered by wire
[60] FIG 18 is a flow chart showing an operation of an examplar software
[61] algorithm in the present invention Mode for the Invention
[62] Fig 1 shows a flat type sensor module(lθ). A target line on the ground plane is assumed x-axis. If the axis perpendicular to the x-axis on the ground plane is z- axis, the axis vertical to the ground plane would be y-axis. Three gyroscopes for the axes (11a, 1 lb, 1 lc) and three accelerometers for the axes(12a, 12b, 12c) are mounted on a circuit board(18). Sensor signal is sent to a diagnostic module by ZigBee chip(15). Some of the sensors can be removed or replaced by direction magnetometer(s). FIG 2 shows a sensor module(10 ') for insertion. Y-axis and z-axis gyroscopes(l la, l ib) and a x axis accelerometer(12b) are mounted on a combined board(18 '). A ZigBee chip(15) and battery(14) are mounted on extra space. FIG 3 and FIG 4 shows a preferred embodiment of the present invention. The diagnosis device consists of two assemblies, a sensor module(10 ') and a diagnostic module(30). The sensor module(lθ') is mounted on the head of a golf club, The diagnostic module(30) is a separate assembly consisting of a radio wave receiving unit, a microcomputer, a LCD graphic display(41) having optionally a speaker(not shown). FIG 5 shows another preferred embodiment of the present invention in which a monolithic diagnosis device is mounted on the head of a putter. The device consists of two layers, which are a sensor module(lθ) and a diagnostic module(30) respectively. LCD(42) of the diagnostic module(30)is located in the upper layer and is covered with protective layer(42'). A microcomputer(31) including a LCD driver chip is mounted at the side of the diagnostic module(30).
[63] FIG 6 is a block diagram to show an operation of another preferred embodiment wherein the diagnosis device consists of a sensor module(lθ) and a diagnostic module(30). Angular velocity signals of gyroscopes for 3 axes (11a, l ib, l ie) and acceleration signals of accelerometers for 3 axes (12a, 12b, 12c) are transmitted via RF switch(17) and ZigBee chip(15) to a RF receiver(35) of the diagnostic module(30) by wireless. The signals are processed by the microcomputer.
[64] FIG 7 is a block diagram to show an operation of the preferred embodiment illustrated in FIG 5 wherein a monolithic diagnosis device consisting of two layers is mounted on the head of a putter. Angular velocity signals of gyroscope of y and z-axes (11a, l ib) and accelerometer's signals (12b) in x-axis are delivered to a mi-
crocomputer(31) to produce swing path values at predetermined points or predetermined times before and after an impact by the signals of the sensors. Right after the impact, the microcomputer(31) calculated a swing path values and compares them with the swing path values of a standard pattern and display the results on a graphic LCD(42).
[65] FIG 8 shows another embodiment wherein a sensor module(lθ) is inserted on the head of a golf club and a diagnostic module(30) is inserted into a grip. A graphic LCD(42) of the diagnostic module is exposed at the top end of the grip. The sensor module is connected by wire through a hole(25) of the club shaft and a battery is inserted near the grip. Operation of this embodiment is similar to FIG 7.
[66] FIG 9 through 13 show operations of a diagnostic algorithm for a golf putter contained in the software routine in the present invention. FIG 9 shows a timetable during a swing. Like the other swing in golf, a putting consists of back swing, down swing and follow swing. A swing starts at an address point where a putter head stops for a moment. Then the head goes back to a stop point. At that point a down swing(or forward swing) starts and goes to a ball till impact. After impact a follow swing starts and goes to the other stop, and a swing is accomplished.
[67] FIG 10 shows change of angular velocity value Ωy of gyroscope 1 la on x-z plane according to the timetable FIG 9. Some values at important points are compared with predetermined standard values. On x-z plane, as an angular velocity(Ωy) approaches "0" in the neighborhood of an impact, the stroke would be better. Ωy is not likely below zero in this case. The display indicates the results as follows.
[68] backswing lf +1 > Ωy(t) > 0, then display "Success",
[69] If +2> Ωy(t) > +1, then display "Close",
[70] If Ωy(t) > +2, then display "Over".
[71] downswing If +l ) Ωy(t) ) 0, then display "Success",
[72] If +2> Ωy(t) > +1, then display "Close",
[73] If Ωy(t) > +2, then display "Over".
[74] follow swing If +1 > Ωy(t) > 0, then display "Success",
[75] If +2> Ωy(t) > +1, then display "Close",
[76] If Ωy(t) > +2, then display "Over".
[77]
[78] FIG 11 shows change of angular velocity value Ωz of gyroscope 1 lb in x-y plane(ground surface) according to the timetable FIG 9. Some values at important points are compared with predetermined standard values. The display indicates the res ults. For putting, smaller value is more desirable for all swings during a cycle.
[79] for backswing If -0.1 > Ωz(t) > 0, 1 then displays "Success",
[80] if -0.1 > Ωz(t)> -0.3 or 0.3 > Ωz(t) > 0.1 then displays "Close",
[81] If Ωz(t) > +0.3 or Ωz(t) <-0.3, then displays "Over".
[82] In place of such expressions as "Success", "Close" and Over", actual values or graphic symbol indicating a swing path like FIG 4 may be displayed.
[83] for down swing If -0.1 Ωz(t) ) 0,1 then displays "Success",
[84] If -0.1 > Ωz(t)> -0.3 or 0.3 > Ωz(t) > 0.1 then displays "Close",
[85] If Ωz(t) > +0.3 or Ωz(t) <-0.3, then displays "Over".
[86] for follow swing If -0.1 > Ωz(t) > 0,1 then displays "Success",
[87] If -0.1 > Ωz(t)> -0.3 or 0.3 > Ωz(t) > 0.1 then displays "Close",
[88] If Ωz(t) > +0.3 or Ωz(t) <-0.3, then displays "Over".
[89] FIG 13 shows change of acceleration g(t) of accelerometer in x-axis according to the timetable FIG 9. The impact strength may be measured by linear acceleration value ax in x-axis. Putting practice is possible in small area by lookup table of distance calculated from impact strength according considering "Fast green" or "Medium green" or "Slow green" condition. FIG 14 and FIG 15 shows a swing path plotted on x- z plane and a swing path plotted on x-y plane respectively. They can be derived by integration of angular velocities and acceleration of the head during a swing cycle. FIG 16 shows measuring of inclination of green by 2 axes accelerometers in a sensor module, A player can notice of an incline of green by the location of a spot in a radial map. The mode may be initiated by a method different from swing diagnosis.
[90] FIG 17 shows a block diagram of an embodiment respectively wherein angular velocity of 3 axes and accelerometer's signals of 3 axes are delivered to mi- crocomputer(31), and swing path information including angular variation and speed of a club head. Right after the impact, the microcomputer calculates speed of club and display some information what the player wants to compare with standard pattern to LCD.
[91] FIG 18 shows a flow chart of processing steps by the software routine including an algorithm according to the present invention. A sensor module and a diagnostic module are powered by switch "on". Analog signals output from sensors and multiplied by a predetermined ratio come into ADC(Analog-to-Digital Converter) via multiplexer. Digital signals converted by ADC, and then input to a microcomputer or a DSP(Digital Signal Processor) chip are processed by the software routine installed to obtain a swing information including swing speed, angular(θx, θy, θz) or linear(vx, vy, vz), and swing path(px, py, pz). The microcomputer or the DSP chip compare the obtained information with such values of a standard swing. A screen display means like LCD displays the results. A speaker with or without a screen display means may generate beep sound according to a tempo modeling a standard swing. Industrial Applicability
[92] By this invention, a diagnosis device for golf to be used in actual or similar situation is provided. A used of the device can analyze and diagnose his swing pattern promptly.