Method for measuring spin information of ball hit and moved

Abstract

The purpose of the present invention is to provide a method for measuring spin information of a ball hit and moved. When a ball used in sports such as golf is hit and moved while rotating, a reflected Doppler signal of a radar signal is received, and digital data of the received signal is acquired and analyzed. Accordingly, the spin axis of the moving ball is calculated in a new manner that cannot be predicted by conventional technology, thereby improving the accuracy of spin axis calculation.

Description

Method for measuring spin information of a ball moving after being struck

[0001] The present invention relates to a method for measuring spin information of a ball that moves upon being struck, wherein radar sensing data is acquired for a sports ball that moves upon being struck by a user, such as a golf ball that moves as a user strikes it with a golf club, by means of a radar sensing device, and spin information of the ball can be acquired through the analysis of the acquired sensing data.

[0002] In sports involving balls, particularly golf, there have always been attempts to accurately sense the physical characteristics of the ball as it moves after being struck by a golfer, use those sensed values ​​for shot analysis, or visualize this data to apply it to simulation golf fields such as so-called screen golf.

[0003] In particular, since the spin of a ball flying due to impact rotates at a very high speed around an axis in three-dimensional space, it is quite difficult to measure it using conventional camera sensors. Consequently, research and development on radar sensors utilizing the Doppler effect of signals is currently underway as equipment capable of calculating the spin of a moving ball more accurately.

[0004] Regarding a conventional method for calculating the spin of a moving ball using a radar sensor, a considerable number of prior art documents have been disclosed, including Patent Application No. 10-2007-7022604, Patent Application No. 10-2015-7021572, Patent Application No. 10-2020-7021865, Japanese Patent Application No. 2010-213710, and US Patent Publication US2016-0306035.

[0005] Among the aforementioned prior art documents, for example, Patent Application No. 10-2020-7021865 discloses technology regarding a radar sensor for detecting a golf ball, and discloses a method of receiving a radar Doppler signal reflected from a rotating ball in flight, arbitrarily dividing the signal into multiple parts in the frequency spectrum of the received signal, calculating the frequency average value of each divided range as an angular position, and calculating the spin axis using the calculated angular positions.

[0006] However, the method for calculating the spin axis of a rotating ball in flight disclosed in the aforementioned patent application No. 10-2020-7021865, etc., has a problem in that the accuracy of the spin axis calculated in this manner is reduced because it obtains an angular position and calculates the spin axis by arbitrarily dividing or fractionating a signal on the frequency spectrum into multiple parts and taking the average value of each divided part.

[0007] The present invention aims to provide a method for measuring spin information of a ball moving while being struck, which can improve the accuracy of spin axis calculation by receiving a reflected Doppler signal of a radar signal and acquiring and analyzing digital data of the received signal when the ball used in sports such as golf moves while rotating upon being struck, thereby calculating the spin axis of the moving ball in a novel way that cannot be predicted by conventional technology.

[0008] A method for measuring spin information of a ball moving after being struck according to an embodiment of the present invention is a method for measuring spin information of a ball moving after being struck using radar sensing data, comprising: a step of generating frequency domain data by processing a Doppler signal received and reflected from a ball moving after being struck after transmitting a radar signal; a step of generating an enlarged spectrum for a specific section corresponding to the ball in the frequency domain data; a step of measuring the relative phase difference between each of a ball frequency portion on the enlarged spectrum and a plurality of harmonic frequency portions formed around the ball frequency; and a step of calculating spin axis information of the moving ball using the measured relative phase difference.

[0009] Meanwhile, a method for measuring spin information of a ball moving after being struck according to another embodiment of the present invention is a method for measuring spin information of a ball moving after being struck using data sensed by a radar sensing device, comprising: a step of generating frequency domain data by processing a Doppler signal received and reflected from a ball moving after being struck after transmitting a radar signal; a step of calculating speed, direction, and ballistic information of the moving ball from the frequency domain data; a step of generating an enlarged spectrum for a specific section corresponding to the ball in the frequency domain data; a step of pre-storing relative phase difference information between a reference pattern regarding the enlarged spectrum and each of the ball frequency and surrounding harmonic frequencies according to the reference pattern, and calculating relative phase difference information between each of the ball frequency and surrounding harmonic frequencies in the generated enlarged spectrum by comparing the generated enlarged spectrum with the reference pattern; and a step of calculating spin axis information of the moving ball using the calculated relative phase difference.

[0010] Additionally, preferably, the radar sensing device is configured to store the reference pattern and the corresponding information in advance for various speeds of the ball or for various travel distances of the ball, and the step of calculating the relative phase difference information is characterized by including the step of extracting a reference pattern corresponding to the information calculated in the step of calculating the speed, direction, and ballistic information of the ball, and the step of determining the relative phase difference information on the generated enlarged spectrum by comparing the generated enlarged spectrum with the extracted reference pattern.

[0011] The method for measuring spin information of a ball moving upon impact according to the present invention has the effect of improving the accuracy of spin axis calculation by receiving a reflected Doppler signal of a radar signal when a ball used in sports such as golf moves while rotating upon impact, and by acquiring and analyzing digital data of the received signal, calculating the spin axis of the moving ball in a new way that cannot be predicted by conventional technology.

[0012] FIG. 1 shows a scene of a user taking a golf shot in a golf course or a field equivalent thereto with a radar sensing device according to one embodiment of the present invention installed.

[0013] FIG. 2 is a block diagram showing the configuration of a radar sensing device according to one embodiment of the present invention.

[0014] Figure 3(a) shows the configuration of the antenna assembly of a radar sensing device, and Figure 3(b) shows the calculation of the phase difference as the radar transmission signal is received with Doppler shift.

[0015] Figure 4 illustrates a signal processing process of a radar sensing device according to one embodiment of the present invention.

[0016] Figure 5 shows a time-velocity (frequency) spectrum as an example of frequency domain data generated by FFT transformation after converting a radar Doppler received signal into a digital signal.

[0017] Figure 6 shows an example of the time-frequency spectrum for a wedge shot.

[0018] Figure 7 shows an example of the time-frequency spectrum for an iron shot.

[0019] Figure 8 shows an example of the time-frequency spectrum for a driver shot.

[0020] Figure 9 is a diagram illustrating the signal characteristics of a rotating and moving ball in radar sensing data.

[0021] Figure 10 shows an example of data generated as a spectrum in the frequency domain by digitally converting a signal reflected from a ball and then performing an FFT transformation.

[0022] FIG. 11 is a flowchart illustrating a method for measuring spin information of a ball that is struck and moves according to an embodiment of the present invention.

[0023] FIG. 12 is a diagram illustrating an example of an enlarged spectrum generated by an additional FFT transform on a specific interval including a portion of frequency domain data based on a radar Doppler signal, and an example of a method for calculating a spin axis using the same.

[0024] FIG. 13 is a drawing for explaining another example of calculating the spin axis of a ball by a method for measuring spin information of a ball that is struck and moves according to one embodiment of the present invention.

[0025] Specific details regarding the method for measuring spin information of a ball moving after being struck according to the present invention will be explained in detail with reference to the drawings.

[0026] First, the configuration of a radar sensing device for measuring spin information of a ball moving after being struck according to one embodiment of the present invention will be explained with reference to FIGS. 1 and 2.

[0027] FIG. 1 shows a scene of a user taking a golf shot while a radar sensing device according to an embodiment of the present invention is installed at a golf course or a field equivalent thereto, and FIG. 2 is a block diagram showing the configuration of a radar sensing device according to an embodiment of the present invention.

[0028] As illustrated in FIG. 1, a radar sensing device (100) according to one embodiment of the present invention can be used by being positioned so as to face forward from the rear of the floor (BT) where a user (U) holds a golf club (20) and strikes a golf ball (10) (the direction in which the golf ball flies by striking).

[0029] A radar sensing device according to one embodiment of the present invention is basically a device that calculates motion information for a moving ball using the Doppler effect of radar, and may be configured to include a signal transmitting unit (110), a signal receiving unit (120), a signal processing unit (130), a sensing processing unit (140), etc. as shown in FIG. 2.

[0030] A radar sensing device according to one embodiment of the present invention is preferably installed on the ground or near the ground at a predetermined distance behind the location of the ball to be struck by the user, and may be configured to transmit a radar signal of a specific frequency toward the direction of movement of the ball to be flown by the strike at the installation location, and to track the moving ball while receiving and analyzing the reflected waves reflected from the ball.

[0031] The signal transmitter (110) is configured to transmit a specific radar signal in a targeted direction and may be configured to include a transmitting antenna that transmits the radar signal, although not shown in the drawing.

[0032] The signal receiving unit (120) is configured to receive a reflected wave signal (Sr) that is reflected back from a moving ball (10) by a radar signal (St) transmitted by the signal transmitting unit (110). Due to the Doppler effect, the reflected wave signal (Sr) transmitted by the signal transmitting unit (110) and reflected from the ball (10) has its frequency changed, causing a Doppler shift. That is, the signal receiving unit (120) receives a signal that has undergone a Doppler shift.

[0033] The signal receiving unit (120) is configured to have a plurality of receiving antennas that receive reflected wave signals, so that information regarding the speed, trajectory, and direction angle of a moving ball can be determined by utilizing the phase difference of the received signals of each of the plurality of receiving antennas. A configuration for calculating the phase difference of the received signals using a plurality of receiving antennas in this manner is illustrated in FIG. 3.

[0034] Figure 3(a) shows the configuration of the antenna assembly of a radar sensing device, and Figure 3(b) shows the calculation of the phase difference as the radar transmission signal is received with Doppler shift.

[0035] The antenna (TX) of the signal transmitter transmits a radar signal (St) toward a moving ball (10), and the signal receiving unit (120) that receives the reflected signal of the radar signal (St) is equipped with a first receiver (121), a second receiver (122), and a third receiver (not shown) that receive the reflected signal reflected from the moving ball (10), and is equipped with an antenna (Rx1) of the first receiver that receives the reflected signal Sr1, an antenna (Rx2) of the second receiver that receives the reflected signal Sr2, and an antenna (Rx3) of the third receiver that receives the reflected signal Sr3.

[0036] A first receiver (121) and a second receiver (122) are arranged in a vertical direction, and a first receiver (121) and a third receiver (not shown) are arranged in a horizontal direction, so that when Rx1, Rx2, and Rx3 each receive a reflected wave signal reflected from a moving ball (10) as shown in FIG. 3 (a), the phase difference of the signal received by the first receiver and the second receiver, i.e., the vertical phase difference, and the phase difference of the signal received by the first receiver and the third receiver, i.e., the horizontal phase difference, can each be calculated.

[0037] Since the principle of calculating the vertical phase difference and the horizontal phase difference is the same, the vertical phase difference of the signal received by the first receiver (121) and the second receiver (122) shown in FIG. 3 (b) will be explained as an example.

[0038] The distance between the antenna (Rx1) of the first receiver (121) and the antenna (Rx2) of the second receiver (122) is fixed at d, and a signal reflected from a target (ball) located at an angle α away from the radar sensing device can be received as shown in FIG. 3 (b).

[0039] The signal reflected from the ball arrives at Rx1 and Rx2 with a path difference, which is d*sinα as a function of the distance d and angle α between the two Rx.

[0040] This path difference appears as a phase difference between signals of different wavelengths, and when the phase difference is denoted as Δφ, it can be expressed by the following mathematical equation 1.

[0041]

[0042]

[0043] Here, d is the distance between the two receivers, α is the angle at which the target ball is offset from the center of the sensor, Δφ is the phase difference of the signals received at each of the two Rx, and λ is the wavelength of the signal.

[0044] If we rearrange the above equation regarding the path difference, the phase difference Δφ can be expressed by the following mathematical equation 2.

[0045]

[0046]

[0047] By using the above-mentioned formula for the phase difference Δφ, the vertical phase difference between Rx1 and Rx2 can be calculated to obtain the ball's trajectory, and the horizontal phase difference between Rx1 and Rx3 can be calculated to obtain the ball's direction.

[0048] In addition, the speed (v) of the moving ball can be calculated by substituting the angle α between the two Rx, the transmission frequency, and the reception frequency into the following mathematical formulas 3 and 4.

[0049]

[0050]

[0051]

[0052]

[0053] Here, f Tx is the radar transmission frequency, and f d is the reflected Doppler frequency, c0 is the speed of light, and v is the speed of the moving ball.

[0054] In other words, the speed, direction, and trajectory of the ball can be calculated using the received radar Doppler shift frequency.

[0055] In addition, by analyzing the Doppler shift frequency reflected from a rotating ball, information such as the spin rate and the inclination of the spin axis of the moving ball can be calculated, which will be described later.

[0056] Figure 4 illustrates a signal processing process of a radar sensing device according to one embodiment of the present invention.

[0057] A signal transmitted through the transmitting antenna (TX) of the antenna assembly (150) is reflected by a moving ball and received by the receiving antennas RX1, RX2, and RX3, respectively, and the received signal (analog signal) is transmitted to the signal processing unit (130). The signal processing unit (130) can generate frequency domain data by filtering the received signal using a Low Pass Filter, amplifying it using an Amplifier, converting it into digital data using an ADC, and then performing a Fast Fourier Transform (FFT) transformation using an FPGA.

[0058] The frequency domain may be data converted into the form of a time-velocity (frequency) spectrum, for example, as shown in Fig. 5.

[0059] In this way, by using the frequency domain data obtained by FFT transformation, the received signal spectrum can be analyzed by separating it into the spectrum of the ball part (100S) and the spectrum of the club part (210S, 220S), and through this, the sensing processing unit (140) can calculate physical values ​​of ball movement such as speed, direction, and trajectory of the ball as previously described.

[0060] Additionally, the sensing processing unit (140) can calculate the spin rate and spin axis of the ball using data in the frequency domain obtained by FFT transformation.

[0061] Looking at the time-frequency spectrum shown in Fig. 5, the position where the spectrum of the ball part begins to appear is the point in time when the ball is impacted by the club, and based on the line (Lim) at the point of impact, the spectrum (210S) according to the movement of the golf club before impact and the spectrum (220S) according to the movement of the golf club after impact can be distinguished and analyzed respectively.

[0062] The movement of the golf club and the ball during a golf shot can vary depending on the type of club, which means that data patterns may differ based on ball speed, distance traveled, or trajectory.

[0063] Figures 6 to 8 show the results of calculating the time-frequency spectrum for each golf club with the time of one data packet set to 4ms.

[0064] Figure 6 shows the spectrum for a wedge shot, Figure 7 shows the spectrum for an iron shot, and Figure 8 shows the spectrum for a driver shot.

[0065] In slow wedge shots, there is a lot of effective ball data and the ball speed is low, whereas as the speed increases towards the driver, you can see that the effective data becomes shorter and the ball speed increases.

[0066] As such, since the characteristics of the data differ depending on the type of golf shot or golf club (i.e., by ball speed, trajectory, and distance), a radar sensing device according to one embodiment of the present invention can calculate spin information by pre-collecting and storing reference data by speed, trajectory, distance, or club type, and comparing it with the result data of a shot made by a user. The features of the present invention will be described later.

[0067] Figure 9 is a diagram illustrating the signal characteristics of a rotating and moving ball in radar sensing data.

[0068] Figure 9 (a) shows the state in which a ball rotates around the Z-axis in the XYZ coordinate system.

[0069] Because the angular velocity differs at each position on the ball as it rotates, the Doppler frequency of the reflected signal varies at each position on the ball when the radar signal is reflected from it.

[0070] When a signal reflected from the ball is digitally converted and then a spectrum in the frequency domain is generated by FFT transformation, the signal reflected at position A, which is the center position of the ball in Fig. 9 (a), appears as the ball's signal, and the signals reflected at positions around position A, such as positions B, C, D, E, etc., appear as harmonic signals in the spectrum.

[0071] Figure 10 shows an example of data generated as a spectrum in the frequency domain by digitally converting a signal reflected from a ball and then performing an FFT transformation.

[0072] In Fig. 10, it can be seen that the spectrum of the signal reflected at position A, which is the center of the ball, i.e., the ball frequency (MF), is clearly visible, and multiple harmonic frequencies (HF) appear around it. Since the speed differs at each position on the ball, the signal reflected at each position appears as the harmonic frequencies described above.

[0073] Because ordinary balls have low radar reflection performance, harmonic frequencies as described above appear relatively faintly. However, if a special material with good radio wave reflection performance is included inside the ball, for example, in the case of a special ball dedicated to radar sensing with a silver band inserted inside the ball, radar signals are reflected well, so harmonic frequencies as described above appear more clearly on the spectrum.

[0074] These harmonic frequencies are represented as the rotational frequency intervals of the ball. If the angle for any position on the ball in Fig. 9 (a) is θ [rad], then the angular velocity at that position is ω = θ / t [rad / s], and the rotational frequency is ω / 2π.

[0075] As shown in Fig. 9(b), assuming the speed of a ball without rotation is constant, the rotational frequency of a ball moving at constant speed while rotating, as shown in Fig. 9(c), will differ from the maximum speed by ω / 2π.

[0076] That is, the harmonic frequencies generated by the signals reflected from each position around the center position of the ball are generated at equal intervals of the ball's rotation frequency ω / 2π.

[0077] Accordingly, as shown in FIG. 10, the spin rate of a moving ball can be calculated by measuring the interval between harmonic frequencies (HF) on the frequency spectrum and converting the frequency corresponding to the measured interval into RPM.

[0078] In addition, the spin axis of the ball can be calculated by measuring the relative phase difference of each harmonic frequency at the ball frequency in the frequency spectrum. Calculating the spin axis of the ball using the relative phase difference of each harmonic frequency with respect to the ball frequency in the frequency spectrum in this way will be described later.

[0079] Meanwhile, a method for measuring spin information of a ball that is struck and moves according to one embodiment of the present invention will be described with reference to the flowchart illustrated in FIG. 11.

[0080] As previously explained through FIG. 4, a radar signal transmitted through an antenna for signal transmission of a radar sensing device is reflected and received by each receiving antenna, and each receiving unit acquires the reflected Doppler signal and transmits it to a signal processing unit, and the signal processing unit can convert it into digital data after filtering and amplification (S100).

[0081] And, as shown in FIG. 5, the signal processing unit can generate frequency domain data such as a time-frequency spectrum by FFT transformation of digital data (S110).

[0082] The sensing processing unit of the radar sensing device can calculate shot data such as the speed, direction, and trajectory of a ball moving while rotating as described above by using the frequency domain data described above (S120).

[0083] Meanwhile, the sensing processing unit searches for a frequency portion to be seen in the frequency domain data (a portion where the signal appears most strongly and appears as data of the portion to be seen in the spectrum) (S130), and can search for a group of candidate harmonic frequencies around that frequency to be seen (S140).

[0084] As previously explained, in the case of the present invention, since a special ball containing a material with radio wave reflection performance can be used as a ball dedicated to radar sensing, harmonic frequencies can appear more clearly. However, in order to obtain a clearer harmonic frequency portion by removing unnecessary noise and increasing the resolution of the spectrum, the above-mentioned frequency domain data can be transformed inversely and filtered, and then an enlarged spectrum with increased resolution for a specific section (ball frequency and its surrounding harmonic frequency portion) can be acquired through an additional FFT transformation (S150). Here, the additional FFT can be performed using techniques such as Zoom FFT, Overlap FFT, Zero Padding FFT, and STFT to increase resolution.

[0085] In this way, after generating an enlarged spectrum through additional FFT transformation, multiple harmonic frequencies around the ball frequency on the enlarged spectrum can be determined (S160), and using this, the spin rate can be calculated (S170) and the spin axis can be calculated (S180).

[0086] Figure 12(a) shows an example of an enlarged spectrum generated for a specific interval around the ball frequency by applying an additional FFT as described above. Here, the horizontal axis represents time and the vertical axis represents frequency.

[0087] When an enlarged spectrum (300) is generated in this way, harmonic frequency portions (321, 322, 323, etc.) around the ball frequency portion (310) can be more clearly shown as illustrated in FIG. 12 (a), and the spin rate and spin axis can be calculated using these.

[0088] For example, as shown in FIG. 12 (b), the intervals (d1, d2, d3) between each harmonic frequency (321, 322, 323, etc.) can be measured and used to calculate the spin rate of the ball.

[0089] In addition, as shown in FIG. 12 (b), the relative phase difference (rPD1, rPD2, rPD3) between each harmonic frequency (321, 322, 323) at the ball frequency (310) can be measured and the spin axis of the ball can be calculated using this.

[0090] For example, in FIG. 12 (a), when the first harmonic frequency (321), the second harmonic frequency (322), and the third harmonic frequency (323) are sequentially referred to as harmonic frequencies close to the ball frequency (310), the relative phase difference between the ball frequency and the first harmonic frequency (rPD1), the relative phase difference between the ball frequency and the second harmonic frequency (rPD2), and the relative phase difference between the ball frequency and the third harmonic frequency (rPD3) can be measured respectively, and a spin axis can be calculated with each of these relative phase differences as the slope, and the slope information of the three-dimensional spin axis can be calculated using the axis measured from the spectrum in the vertical direction of RX1 and RX2 and the axis measured from the spectrum in the horizontal direction of RX1 and RX3.

[0091] However, since the portions for the ball frequency (310) and each harmonic frequency (321, 322, 323) do not appear as accurate lines but as data distributed over a predetermined range, in order to obtain the relative phase difference, for example, as shown in FIG. 12 (b), a trend line (410) for the ball frequency portion is derived, and a trend line (421, 422, 423) for each harmonic frequency portion is derived, and the relative phase difference can be calculated using frequency information corresponding to each trend line.

[0092] In addition, when an enlarged spectrum (300) is generated based on a signal received according to a user's shot, it is possible to calculate the relative phase difference on the enlarged spectrum by comparing it with a pre-prepared reference pattern, rather than directly measuring and calculating the relative phase difference on the enlarged spectrum graph as in (b) of FIG. 12, when an enlarged spectrum (300) is generated based on a signal received according to a user's shot, by preparing a reference pattern that already knows the information regarding the relative phase difference, and this is explained with reference to FIG. 13.

[0093] A radar sensing device implementing a method for measuring spin information of a ball according to one embodiment of the present invention can store a reference pattern for an enlarged spectrum as described in FIG. 12 in advance, and the relative phase difference information of the reference pattern is stored in advance.

[0094] However, since the pattern of the expanded spectrum can vary significantly depending on the type of shot, that is, by speed, distance, and trajectory (see FIGS. 6 to 8), the radar sensing device may be equipped with a speed-specific reference pattern LB (510) that stores a reference pattern for each of the various speeds, as shown in FIG. 13.

[0095] For example, the speed of the ball can be stored in the speed-specific reference pattern LB (510) by preparing the reference pattern of the enlarged spectrum and the relative phase difference information on each reference pattern at intervals of 5 m / s.

[0096] The radar sensing device may be equipped with a distance-specific reference pattern LB (520) that stores a reference pattern for each of various distances, or may be equipped together with the above-mentioned speed-specific reference pattern LB (510).

[0097] For example, the distance traveled by the ball can be stored in the distance-specific reference pattern LB (520) by preparing the reference pattern of the enlarged spectrum and the relative phase difference information on each of the reference patterns at intervals of 10m.

[0098] The radar sensing device may be equipped with a ballistic reference pattern LB (530) that stores a reference pattern for each of the various ballistics, or may be equipped together with the above-mentioned speed reference pattern LB (510) and / or distance reference pattern LB (520).

[0099] For example, reference patterns of enlarged spectra and relative phase difference information on each reference pattern can be prepared in advance for each ball's trajectory at 2° intervals and stored in the trajectory-specific reference pattern LB (530).

[0100] Accordingly, when a user takes a shot and the ball moves while rotating, the radar sensing device receives a radar Doppler signal, first calculating information such as the ball's speed, direction, and trajectory, and then, when an enlarged spectrum (300) is generated based on the radar Doppler signal, the sensing processing unit of the radar sensing device can use the ball's speed, direction, and trajectory information calculated in advance as described above to extract a reference pattern corresponding to the speed from the speed-specific reference pattern LB (510), compare it with the generated enlarged spectrum (300) to determine similarity, calculate a difference value, and reflect that difference value in the information of the reference pattern to determine relative phase difference information, and based on this, calculate information about the spin axis.

[0101] Likewise, the sensing processing unit of the radar sensing device can determine relative phase difference information by using the ball's speed, direction, and ballistic information calculated in advance as described above to extract a reference pattern corresponding to the distance or ballistic from the distance-specific reference pattern LB (520) or the ballistic-specific reference pattern LB (530), compare it with the generated enlarged spectrum (300) to determine similarity, calculate a difference value, and reflect that difference value in the information of the reference pattern, and can calculate information about the spin axis based on this.

[0102] Alternatively, when an enlarged spectrum (300) based on radar sensing data for a user's shot is generated, it is also possible to calculate the final spin axis information by using the previously calculated ball speed, direction, and ballistic information to extract the corresponding reference pattern from the speed-based reference pattern LB (510), distance-based reference pattern LB (520), and ballistic-based reference pattern LB (530), and statistically fusing the respective result information derived from the result of comparing each of the reference patterns with the corresponding enlarged spectrum (300) (e.g., taking the average value).

[0103] In other words, the final spin axis information is calculated by comparing and analyzing, image by image, a reference pattern with known spin axis information and the pattern of the magnified spectrum generated according to the shot.

[0104] As such, the method for measuring spin information of a ball moving after being struck according to the present invention can calculate information such as the speed, direction, and trajectory of the moving ball using radar sensing data for the ball moving after being struck, and can easily calculate information for calculating the spin axis by comparing a reference pattern extracted based on the speed of the ball, etc., with the enlarged spectrum of the part relating to the ball based on the radar sensing data.

[0105] The method for measuring spin information of a ball moving after being struck according to the present invention is applicable to devices and systems based on radar sensing of a ball moving after being struck, and can be used in all golf-related industrial fields that utilize it.

Claims

1. A method for measuring spin information of a ball moving after being struck using radar sensing data, A step of generating frequency domain data by processing the Doppler signal received and reflected from a moving ball after transmitting a radar signal; A step of generating an enlarged spectrum for a specific section corresponding to a ball in the above frequency domain data; A step of measuring the relative phase difference between each of the ball frequency portion on the expanded spectrum and a plurality of harmonic frequency portions formed around the ball frequency; and A step of calculating spin axis information of the moving ball using the measured relative phase difference; A method for measuring spin information of a ball moving after being struck, including 2. A method for measuring spin information of a ball moving upon impact using data sensed by a radar sensing device, A step of generating frequency domain data by processing the Doppler signal received and reflected from a moving ball after transmitting a radar signal; A step of calculating the speed, direction, and ballistic information of the moving ball from the above frequency domain data; A step of generating an enlarged spectrum for a specific section corresponding to a ball in the above frequency domain data; A step of pre-storing relative phase difference information between a reference pattern regarding the enlarged spectrum and each of the ball frequency and surrounding harmonic frequencies according to the reference pattern, and calculating relative phase difference information between each of the ball frequency and surrounding harmonic frequencies in the generated enlarged spectrum by comparing the generated enlarged spectrum with the reference pattern; and A step of calculating spin axis information of the moving ball using the relative phase difference calculated above; A method for measuring spin information of a ball moving after being struck, including 3. In paragraph 2, the radar sensing device is configured to store the reference pattern and the corresponding information in advance for various speeds of the ball or for various travel distances of the ball, and The step of calculating the above relative phase difference information is, A step of extracting a reference pattern corresponding to the information calculated in the step of calculating the speed, direction, and trajectory information of the ball, and A method for measuring spin information of a ball moving after being struck, characterized by including the step of determining relative phase difference information on the generated enlarged spectrum by comparing the generated enlarged spectrum with the extracted reference pattern.

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