JP5617480B2 - Ball measuring device and ball measuring method - Google Patents

Description

  The present invention relates to a ball measuring device and a ball measuring method using the Doppler method, and more particularly to a ball measuring device and a ball measuring method for measuring the speed and spin rate of a golf ball.

At present, as a method for measuring the speed of a moving body, a Doppler method is widely known in which radio waves or ultrasonic waves are transmitted as transmission waves and the speed is calculated from a frequency change with a reflected wave from the moving body. This Doppler method is used in a speed measuring device that measures the moving speed of a ball game ball such as a golf ball or a baseball ball.
As a velocity measuring device, for example, a device that obtains an average velocity of a moving body in a certain period by analyzing a Doppler signal output from a Doppler sensor using, for example, FFT (Fast Fourier Transform) has been proposed. . In addition to this, various measuring devices related to golf using the Doppler method have been proposed (see Patent Documents 1 and 2).

In Patent Document 1, a transmitter / receiver that operates to transmit a radar signal and receive a radar signal reflected from a moving club head, and a speed signal from the transmitted / received radar signal are connected to the transmitter / receiver. A detector that operates to detect, extracts a swing speed output signal that indicates a moving club head speed and a swing tempo output signal that indicates a club head swing time, connected to the detector and processing the speed signal; An apparatus for measuring the swing movement of a golf club comprising a processor programmed in this way is described.
The transceiver transmits and receives a continuous wave signal, and the club head speed can be captured by returning a Doppler signal from the continuous wave signal. The continuous wave signal can be an ultrasonic signal, an electromagnetic wave signal, or various continuous wave signals.
In Patent Document 1, a value for the maximum swing speed is stored, and the speed of a motion arbitrarily detected in a predetermined time longer than the longest expected swing time is continuously measured. At this time, the stored value of the maximum speed is replaced by any measurement speed that is faster than the previously stored speed.

  Patent Document 2 discloses a Doppler sensor that outputs a Doppler signal, storage means that can store a plurality of data related to the period of the Doppler signal based on the Doppler signal output by the Doppler sensor, and a Doppler signal output by the Doppler sensor. A swing speed measuring apparatus is provided that includes data relating to the period of the Doppler signal based on the data, stores the data in the storage means, and calculates the swing speed based on the data group stored in the storage means. .

JP 2006-326318 A JP 2008-246139 A

In the above-mentioned Patent Documents 1 and 2, it is limited to measuring the maximum speed of the swing and the like, and it cannot be said to be sufficient for measuring various physical quantities representing the behavior of a ball such as a golf ball.
Therefore, currently, a measuring device for measuring the spin rate in addition to the moving speed of the hit golf ball by analyzing the Doppler signal output from the Doppler sensor is provided (for example, TrackMan (TrackMan A / Registered trademark of company S)).

However, in this measuring device, in order to obtain Doppler signal data necessary for calculating the spin rate, it is necessary to measure for a long time over a period in which the hit golf ball is flying in the air in units of 100 m. For this reason, in order to reliably receive the reflected wave from the golf ball, it is necessary to increase the output of the transmission wave from the device, and there is a problem that the speed measuring device becomes large and expensive.
Moreover, when measuring the behavior of a golf ball hit in a room such as a golf simulator using the above-described measuring device, the flight distance of the golf ball is a short distance of about several meters. For this reason, the above-described measuring apparatus has a problem that data necessary for measuring the spin amount cannot be obtained, and an accurate spin amount cannot be obtained.

  An object of the present invention is to provide a ball measuring device and a ball measuring method that can solve the problems based on the conventional technology and can easily measure the speed and spin rate of a ball such as a golf ball.

  In order to achieve the above object, a first aspect of the present invention is supplied toward a ball having a first region having radio wave reflectivity and a second region having a radio wave reflectivity lower than the first region. Transmitting a transmission wave based on a transmission signal to be transmitted, receiving an reflected wave reflected by the ball and generating a reception signal, supplying the transmission signal to the antenna, and being supplied from the antenna Based on the received signal, a Doppler sensor that creates a Doppler signal having a Doppler frequency, an analysis unit that creates a signal strength distribution data indicating a signal strength distribution for each frequency by analyzing the frequency of the Doppler signal, and A moving speed calculation unit that calculates a moving speed of the ball based on the signal intensity distribution data, and the baud based on the signal intensity distribution data. A spin amount calculation unit for calculating a spin amount of the antenna, wherein the antenna is configured by a directional antenna, and the analysis unit performs a frequency analysis of the Doppler signal to calculate the total number of analysis data. Among them, a ball measuring device is provided in which the Doppler signal is used for at least 20% of data and the remaining data is set to 0.

The analysis unit further performs moving average processing on the signal intensity distribution data to create moving average waveform data, and the moving speed calculation unit calculates the ball based on the moving average waveform data. It is preferable that the moving speed is calculated, and the spin amount calculation unit calculates the spin amount of the ball based on the moving average waveform data.
In this case, the moving speed calculation unit calculates the maximum value of the signal intensity in the frequency domain derived from the movement of the ball from the moving average waveform data, and the moving speed of the ball based on the maximum value. Is preferably calculated.

In addition, the spin amount calculation unit calculates a portion of the moving average waveform data that changes in a mountain shape including a maximum value of the signal intensity in a frequency region derived from the movement of the ball, and changes to the mountain shape. It is preferable to calculate a difference in frequency of the portions to be calculated and calculate the spin amount of the ball based on the difference in frequency.
Further, the difference in frequency is the difference in frequency in the portion where the signal intensity becomes the threshold value Dt when the maximum value of the signal intensity is Dmax and the threshold value Dt is Dmax · n (where 0 <n <1). It is preferable that

  The second aspect of the present invention provides a transmission wave based on a transmission signal supplied to a ball having a first region having radio wave reflectivity and a second region having a radio wave reflectivity lower than the first region. The transmission signal is transmitted to each of the first to fourth antennas that receive the reflected wave reflected by the ball and generate a reception signal, and the first to fourth antennas. And a first Doppler sensor to a fourth Doppler sensor for creating a Doppler signal having a Doppler frequency based on the received signals supplied from the first antenna to the fourth antenna, and The first Doppler sensor to the fourth Doppler signal created by the first Doppler sensor to the fourth Doppler sensor are each analyzed by frequency analysis. Based on the first signal intensity distribution data to the fourth signal intensity distribution data indicating the signal intensity distribution for each number, and the first signal intensity distribution data to the fourth signal intensity distribution data. A moving speed calculating unit that calculates a moving speed and a moving direction of the ball, and a spin amount calculating unit that calculates the spin amount of the ball based on the first signal intensity distribution data to the fourth signal intensity distribution data. And the analysis unit performs total analysis data for each of the first Doppler signal to the fourth Doppler signal when performing frequency analysis on the first Doppler signal to the fourth Doppler signal. Of the number, the first Doppler signal to the fourth Doppler signal are used for at least 20% of the data, and the remaining data is set to 0, and the first antenna The fourth antenna is a directional antenna, is provided on the side opposite to the moving direction of the ball, and the first antenna to the third antenna have a predetermined interval in the horizontal direction. Provided is a ball measuring device characterized in that a fourth antenna is arranged with a predetermined interval in the vertical direction above the second antenna, with the second antenna arranged in the center with a gap therebetween To do.

  The analysis unit further performs a moving average process on the first signal intensity distribution data to the fourth signal intensity distribution data to generate first moving average waveform data to fourth moving average waveform data. The moving speed calculation unit has a maximum signal intensity in a frequency domain derived from the movement of the ball for each of the first moving average waveform data to the fourth moving average waveform data. It is preferable to calculate a value and calculate a moving speed and a moving direction of the ball based on the maximum values of the waveform data of the first moving average to the waveform data of the fourth moving average.

  In the second antenna, a first virtual axis indicating a directivity direction extends in a horizontal direction, and in the fourth antenna, a second virtual axis indicating directivity intersects the first virtual axis. The analysis unit further performs a moving average process on the second signal intensity distribution data and the fourth signal intensity distribution data to obtain second moving average waveform data and fourth The moving average waveform data is generated, and the spin amount calculation unit is a frequency region derived from the movement of the ball with respect to the second moving average waveform data and the fourth moving average waveform data, respectively. And calculating the difference in the peak shape including the maximum value of the signal intensity, calculating the difference in the frequency in the peak change portion, and based on the difference in the frequency of the waveform data of the fourth moving average The ball spin And calculating the direction of the rotation axis of the ball based on the difference between the frequency difference of the waveform data of the second moving average and the difference of the frequency of the waveform data of the fourth moving average. It is preferable to calculate.

  According to a third aspect of the present invention, an antenna configured by a directional antenna is directed toward a ball having a first region having radio wave reflectivity and a second region having radio wave reflectivity lower than the first region. A transmission wave is transmitted based on the supplied transmission signal, a reflected wave reflected by the ball is received by the antenna to generate a reception signal, and a Doppler signal having a Doppler frequency is created based on the reception signal Performing a frequency analysis of the Doppler signal, creating a signal intensity distribution data indicating a signal intensity distribution for each frequency, and calculating a moving speed of the ball based on the signal intensity distribution data. Calculating a spin amount of the ball, and performing frequency analysis of the Doppler signal, at least 20% of the total number of analysis data The Doppler signal using the data, there is provided a ball measurement method characterized by the remaining data to 0.

The step of calculating the moving speed of the ball further generates a moving average waveform data by performing a moving average process on the signal intensity distribution data, and calculates the moving speed of the ball based on the moving average waveform data. Preferably, the step of calculating the spin amount of the ball calculates the spin amount of the ball based on the moving average waveform data.
Further, in the step of calculating the moving speed of the ball, a maximum value of signal intensity in a frequency domain derived from the movement of the ball is calculated from the waveform data of the moving average, and the ball is calculated based on the maximum value. It is preferable to calculate the moving speed of
Furthermore, the step of calculating the moving speed of the ball calculates a portion of the moving average waveform data that changes in a mountain shape including the maximum value of the signal strength in the frequency domain derived from the movement of the ball, It is preferable to calculate a difference in frequency of the mountain-like portion and calculate a spin amount of the ball based on the difference in frequency.
Further, the difference in frequency is the difference in frequency in the portion where the signal intensity becomes the threshold value Dt when the maximum value of the signal intensity is Dmax and the threshold value Dt is Dmax · n (where 0 <n <1). It is preferable that

  According to a fourth aspect of the present invention, there is provided a first directional antenna configured to face a ball having a first region having radio wave reflectivity and a second region having a radio wave reflectivity lower than the first region. A transmission wave is transmitted from an antenna to a fourth antenna, a reflected wave reflected by the ball is received by each of the first antenna to the fourth antenna, and a reception signal is generated. Based on each reception signal The first Doppler signal to the fourth Doppler signal having a Doppler frequency are created, and the first Doppler signal to the fourth Doppler signal are analyzed by frequency analysis, and the signal strength for each frequency is analyzed. A first signal intensity distribution data to a fourth signal intensity distribution data indicating a distribution; and the baud based on the first signal intensity distribution data to the fourth signal intensity distribution data. Calculating a moving speed and a moving direction of the first Doppler signal, and calculating a spin amount of the ball, and performing the frequency analysis on the first Doppler signal to the fourth Doppler signal. For each of the signal to the fourth Doppler signal, the first Doppler signal to the fourth Doppler signal are used for at least 20% of the total number of analysis data, and the remaining data is set to 0. The first antenna to the fourth antenna are provided on the side opposite to the moving direction of the ball, and the first antenna to the third antenna are spaced apart from each other in a horizontal direction. The second antenna is arranged around the second antenna, and the fourth antenna is arranged above the second antenna at a predetermined interval in the vertical direction. There is provided a measurement method.

  The step of calculating the moving speed and the moving direction of the ball further performs a moving average process on the first signal intensity distribution data to the fourth signal intensity distribution data to obtain first moving average waveform data to 4 moving average waveform data is created, and the first moving average waveform data to the fourth moving average waveform data are respectively the maximum value of the signal intensity in the frequency domain derived from the movement of the ball. And the moving speed and moving direction of the ball are preferably calculated based on the maximum values of the first moving average waveform data to the fourth moving average waveform data.

  Further, the second antenna has a first virtual axis indicating a directivity direction extending in the horizontal direction, and the fourth antenna has a second virtual axis indicating directivity intersecting the first virtual axis. In the step of calculating the spin amount of the ball, the second signal intensity distribution data and the fourth signal intensity distribution data are further subjected to moving average processing to obtain a second moving average Waveform data and fourth moving average waveform data are created, and the second moving average waveform data and the fourth moving average waveform data are respectively measured in the frequency domain derived from the movement of the ball. Calculating a portion including a maximum value and changing in a mountain shape, calculating a difference in frequency of the portion changing in the mountain shape, and calculating the difference between the frequencies of the waveforms in the waveform data of the fourth moving average. Calculate spin amount In addition, the direction of the rotation axis of the ball is calculated based on the difference between the frequency difference of the waveform data of the second moving average and the difference of the frequency of the waveform data of the fourth moving average. It is preferable to do.

  According to the present invention, the speed and spin rate of a ball such as a golf ball can be easily measured. In addition, the time required for calculating the ball speed and the spin rate can be shortened.

It is a mimetic diagram showing a ball measuring device concerning an embodiment of the present invention. It is a typical top view which shows arrangement | positioning of the antenna of the ball | bowl measuring device of embodiment shown in FIG. (A) is a side view which shows arrangement | positioning of the antenna of the ball | bowl measuring device of embodiment shown in FIG. 1, (b) is a top view which shows arrangement | positioning of the antenna of the ball | bowl measuring device of embodiment shown in FIG. is there. It is a schematic diagram which shows the principle of the measurement of the spin amount of a golf ball. (A) is a schematic diagram which shows the state which looked at the golf ball along the virtual axis of the 4th antenna, (b) is the schematic which shows the state which looked at the golf ball along the virtual axis of the 2nd antenna It is a figure, (c) is a schematic diagram which shows the state which looked at the golf ball along the virtual axis of the 4th antenna, (d) is the state which looked at the golf ball along the virtual axis of the 2nd antenna. (E) is a schematic view showing a state where the golf ball is viewed along the virtual axis of the fourth antenna, and (f) is a schematic view showing the golf ball along the virtual axis of the second antenna. It is a schematic diagram which shows the state seen. It is a graph which shows an example of the time waveform of a Doppler signal. It is a graph which shows distribution of the signal strength for every frequency obtained by carrying out frequency analysis of the time waveform of the Doppler signal shown in FIG. It is a principal part enlarged view of the graph shown in FIG. (A) is a graph which shows the time waveform of a Doppler signal, (b) is a graph which shows the result of having Fourier-transformed changing the conditions about the time waveform of the Doppler signal shown to Fig.9 (a). (A) is a graph which shows the time waveform of a Doppler signal, (b) is a graph which shows the result of having Fourier-transformed changing the conditions about the time waveform of the Doppler signal shown to Fig.10 (a). It is a graph which shows the actual measurement result of spin amount SP and difference (DELTA) SP of the golf ball which carries out backspin. It is a graph which shows the actual measurement result of spin amount SP and difference (DELTA) SP of the golf ball which carries out the side spin. (A) is a schematic diagram which shows an example of the golf ball used for the ball | bowl measuring device of embodiment of this invention, (b) is another golf ball used for the ball | bowl measuring device of embodiment of this invention. It is a schematic diagram which shows an example. It is a flowchart which shows the measuring method by the ball | bowl measuring device of embodiment of this invention in order of a process. It is a schematic diagram which shows the frequency analysis method in the ball | bowl measuring device of embodiment of this invention. (A)-(d) is a graph which shows the result obtained by the frequency analysis method shown in FIG. (A)-(e) is a graph which shows the result obtained by the frequency analysis method shown in FIG.

Hereinafter, based on preferred embodiments shown in the accompanying drawings, a ball measuring device and a ball measuring method of the present invention will be described in detail.
FIG. 1 is a schematic diagram showing a ball measuring apparatus according to an embodiment of the present invention.

A ball measuring device 10 shown in FIG. 1 measures, for example, the behavior of a golf ball hit by a golf club head by swinging a golf club. The ball measuring device 10 includes, for example, four first antennas 14a to 14d, four first Doppler sensors 16a to 16d, and four first signal processing units 18a to 18d. 4 signal processing unit 18d, arithmetic processing unit 20, display unit 24, and operation unit 26. The arithmetic processing unit 20 includes a CPU 22, a detection unit 28, a storage unit 30, and a behavior calculation unit 32.
The first antenna 14a to the fourth antenna 14d are connected to the first Doppler sensor 16a to the fourth Doppler sensor 16d, respectively.
Hereinafter, the first antenna 14a to the fourth antenna 14d are referred to as antennas 14a to 14d. The first to fourth Doppler sensors 16a to 16d are referred to as Doppler sensors 16a to 16d.
Each of the Doppler sensors 16a to 16d is connected to each signal processing unit of the first signal processing unit 18a to the fourth signal processing unit 18d.

In the ball measurement device 10, even if the CPU 22, the detection unit 28, the storage unit 30, and the behavior calculation unit 32 are configured by hardware such as a circuit, the CPU 22 executes the control program. It may be done.
The CPU 22 controls the display unit 24, the detection unit 28, the storage unit 30, and the behavior calculation unit 32, and moves the data displayed between the display unit 24, each detection unit 28, the storage unit 30 and the behavior calculation unit 32. Is also controlled. The CPU 22 also controls display on the display unit 24 based on an instruction input from the operation unit 26.

The antennas 14a to 14d transmit the microwaves as the transmission waves W1 to the moving body based on the transmission signals supplied from the Doppler sensors 16a to 16d, respectively, and receive the reflected waves W2 reflected by the golf ball b Thus, a reception signal is generated, and each reception signal is supplied to each of the Doppler sensors 16a to 16d.
The antennas 14a to 14d are configured by directional antennas, and for example, parabolic antennas are used. The antennas 14a to 14d are not limited to parabolic antennas as long as they are directional antennas, and various conventionally known directional antennas other than parabolic antennas can be used.

In the present embodiment, as shown in FIG. 2 and FIG. 3A, four antennas 14a to 14d are arranged on the opposite side of the moving direction (flying direction) of the golf ball b. For example, the four antennas 14a to 14d may be provided in the same frame (not shown).
The four antennas 14a to 14d are installed, for example, at a position about 1 m to 1.5 m behind the golf ball b. The golf ball b is placed on the tee 104, for example.

As shown in FIG. 2, the fourth antenna 14d is arranged above the second antenna 14b with a Δy interval so that the center position in the horizontal direction coincides with the second antenna 14b.
As shown in FIG. 3A, the fourth antenna 14d has a virtual axis LD indicating the directivity direction extending in the horizontal direction, and the second antenna 14b has a virtual axis LB indicating the directivity direction as the virtual axis. The intersection with the LD is arranged so as to intersect with a vertical line L passing through the center O of the golf ball b placed on the tee 104. By doing in this way, ensuring of the electric field strength of the transmission wave W1 which reaches | attains the golf ball b from the 2nd antenna 14b and the 4th antenna 14d is achieved.

As shown in FIG. 2, the first antenna 14a to the third antenna 14c are arranged around the second antenna 14b at a predetermined interval in the horizontal direction with the second antenna 14b interposed therebetween. The first antenna 14a and the third antenna 14c are arranged with an interval of Δx / 2 so that the center positions in the vertical direction coincide with each other.
In addition, as shown in FIG. 3B, the virtual axes LA and LC in a plan view are from the target line L0 when hitting the golf ball b, that is, from the tee 104 to the target point hitting the golf ball b. It matches the virtual line connecting
The virtual axes LA and LC of the first antenna 14a and the third antenna 14c are arranged so as to intersect with a vertical line passing through the center O of the golf ball b placed on the tee 104 in a plan view. .
The distance between the intersection of the virtual axes LA and LC and the first antenna 14a is the same as the distance between the intersection and the third antenna 14c. By doing in this way, ensuring of the electric field strength of the transmission wave W1 which reaches | attains the golf ball b from the 1st antenna 14a and the 3rd antenna 14c is achieved.

Each of the Doppler sensors 16a to 16d supplies a transmission signal to each of the antennas 14a to 14d that transmits the transmission wave W1 toward the golf ball b, and receives the reflected wave W2 reflected by the golf ball b and receives the reception signal. A reception signal is supplied from each of the generated antennas 14a to 14d. The Doppler sensors 16a to 16d respectively generate a first Doppler signal Sd1 to a fourth Doppler signal Sd4 having a Doppler frequency based on the received signal. As the Doppler signal Sd2 having the Doppler frequency, for example, a signal with a waveform α is obtained as described later (see FIG. 6).
Hereinafter, the first Doppler signal Sd1 to the fourth Doppler signal Sd4 are referred to as Doppler signals Sd1 to Sd4.

The Doppler signals Sd1 to Sd4 have a first Doppler frequency Fd1 to a fourth Doppler frequency Fd4 defined by a frequency F1-F2 that is a difference between the frequency F1 of the transmission signal and the frequency F2 of the reception signal. Signal.
Hereinafter, the first Doppler frequency Fd1 to the fourth Doppler frequency Fd4 are referred to as Doppler frequencies Fd1 to Fd4.
As the Doppler sensors 16a to 16d, for example, various commercially available sensors can be used.
For example, a microwave having a carrier frequency of 24 GHz can be used as the transmission signal described above, and the frequency of the transmission signal is not particularly limited as long as the Doppler signals Sd1 to Sd4 can be obtained.

The four first signal processing units 18a to 18d amplify the Doppler signals Sd1 to Sd4 supplied from the Doppler sensors 16a to 16d, and set the low level with a predetermined threshold as a reference. The signal is converted into a binary signal that takes a binary value of high level. That is, each of the Doppler signals Sd1 to Sd4 is sampled at a predetermined sampling frequency and converted into digital data by the first signal processing unit 18a to the fourth signal processing unit 18d.
Therefore, the period of each Doppler signal Sd1 to Sd4 corresponds to the period of the binarized signal. In other words, the frequency of each Doppler signal Sd1 to Sd4 corresponds to the frequency of the binarized signal.
Hereinafter, the first signal processing unit 18a to the fourth signal processing unit 18d are referred to as signal processing units 18a to 18d.

  The arithmetic processing unit 20 calculates the moving direction, moving speed, and spin rate of the golf ball b by inputting the amplified binarized data supplied from the signal processing units 18a to 18d and performing various processes. To do.

The detection unit 28 converts the binarized signals (Doppler signals Sd1 to Sd4) supplied from the signal processing units 18a to 18d into first to fourth intermediate data associated with Doppler frequencies Fd1 to Fd4. In addition to the conversion, the first intermediate data to the fourth intermediate data are sampled at a predetermined sampling period. Hereinafter, the first to fourth intermediate data are referred to as each intermediate data.
In the present embodiment, the detection unit 28 creates the period of the binarized signal as each intermediate data by counting the period of the binarized signal using a counter.
In other words, the detection unit 28 obtains period data as time series data by counting the period of the Doppler signal Sd, and creates this period data as each intermediate data associated with the Doppler frequency Fd. Therefore, the value of each intermediate data and the Doppler frequencies Fd1 to Fd4 are inversely proportional.
In the present embodiment, the case where each piece of intermediate data associated with the Doppler frequencies Fd1 to Fd4 is periodic data will be described, but each piece of intermediate data may be data of a frequency representing the Doppler frequencies Fd1 to Fd4. Good.

  The accumulation unit 30 accumulates each intermediate data sampled by the detection unit 28 in order as time elapses. The storage unit 30 also functions as a memory in the arithmetic processing unit 20.

  The behavior calculating unit 32 calculates the moving direction, moving speed, and spin amount of the golf ball b based on each intermediate data stored in the storing unit 30. The behavior calculation unit 32 includes an analysis unit 34, a movement speed calculation unit 36, and a spin amount calculation unit 38.

Here, the principle of measurement of the moving speed and the spin rate of the golf ball b will be described.
As is conventionally known, the Doppler frequency Fd is expressed by Expression (1).
Fd = F1-F2 = V · F1 / c (1)
Where V: moving speed of golf ball b (m / s), c: speed of light (3 × 10 ⁸ m / s)
Therefore, when equation (1) is solved for V, equation (2) is obtained.
V = c · Fd / F1 (2)
That is, the moving speed V of the golf ball b is proportional to the Doppler frequency Fd. Therefore, the Doppler frequency Fd can be detected from the Doppler signal Sd, and the moving speed V of the golf ball b can be obtained from the Doppler frequency Fd.

FIG. 4 is a schematic diagram showing the principle of measuring the spin rate of a golf ball.
Of the surface of the golf ball b, the transmission wave W1 is efficiently reflected at the first portion A, which is the surface portion where the angle formed with the transmission direction of the transmission wave W1 is close to 90 degrees. The strength of W2 is high.
On the other hand, the transmission wave W1 is not efficiently reflected in the second part B and the third part C, which are parts of the surface of the golf ball whose surface makes an angle with the transmission direction of the transmission wave W1 close to 0 degrees. In the second part B and the third part C, the intensity of the reflected wave W2 is low.
The second portion B is a portion in which the direction rs that moves due to the spin of the golf ball b is opposite to the direction in which the golf ball moves.
The third portion C is a portion in which the direction rs that moves due to the spin of the golf ball b is the same as the direction in which the golf ball moves.

The velocity detected based on the reflected wave W2 reflected by the first portion A is the first velocity VA, the velocity detected based on the reflected wave W2 reflected by the second portion B is the second velocity VB, the third. A speed detected based on the reflected wave W2 reflected by the portion C is defined as a third speed VC.
Then, the following formula is established.
VA = V (3)
VB = VA−ωr (4)
VC = VA + ωr (5)
(Where V is the moving speed of the golf ball b, ω is the angular velocity (rad / s), r is the radius of the golf ball b)

Therefore, in principle, the moving speed V of the golf ball b can be calculated from the first speed VA based on the formula (3), and the second and third speeds VB can be calculated based on the formula (4) or (5). Since the angular velocity ω is obtained from VC, the spin rate can be calculated from the angular velocity ω.
However, in the present embodiment, instead of calculating the moving speed V and the spin amount based on the above equations, the signal intensity distribution for each frequency is obtained by frequency analysis of the Doppler signal Sd as described below. The signal intensity distribution data shown is generated, and the moving speed V and the spin amount are obtained from the signal intensity distribution data.

Next, the relationship between the positions of the antennas 14a to 14d, the spin amount of the golf ball b, and the rotation axis of the golf ball b will be described.
5 (a), 5 (c), and 5 (e) are schematic views showing a state in which the golf ball b is viewed along the virtual axis LD (FIG. 3 (a)) of the fourth antenna 14d. 5 (b), 5 (d), and 5 (f) are schematic views showing a state where the golf ball b is viewed along the virtual axis LB (FIG. 3 (a)) of the second antenna 14b. is there.

5A and 5B show a state in which the rotation axis M of the golf ball b is parallel to the horizontal plane on a vertical plane orthogonal to the reference line L01. In this case, the back spin is applied to the golf ball b.
5C and 5D show a state where the rotation axis M of the golf ball b is inclined by 45 ° with respect to the horizontal plane on a vertical plane perpendicular to the reference line L01. In this case, the golf ball b is subjected to an intermediate spin between the back spin and the side spin.
5E and 5F show a state in which the rotation axis M of the golf ball b is orthogonal to the horizontal plane on a vertical plane orthogonal to the reference line L01. In this case, a side spin is applied to the golf ball.
The reference line L01 indicates a reference line passing through the center O of the golf ball b and parallel to the target line L0.

  As shown in FIG. 3A, when the golf ball b is viewed along the imaginary axis LD of the fourth antenna 14d, the golf ball b is viewed from the front, and the imaginary axis LB of the second antenna 14b is observed. When the golf ball b is viewed along, the golf ball b is viewed obliquely from below.

  Therefore, as shown in FIGS. 5 (a), 5 (c), and 5 (e), when the golf ball b is viewed along the virtual axis LD of the fourth antenna 14d, the golf ball b rotates. Regardless of which direction the axis M faces, the spin amount of the golf ball b looks the same. In other words, the first spin amount SPA measured using the fourth antenna 14d is the same regardless of the direction of the rotation axis M of the golf ball b.

On the other hand, as shown in FIGS. 5B, 5D, and 5F, when the golf ball b is viewed along the virtual axis LB of the second antenna 14b, the golf ball b rotates. When the direction of the axis M changes, the spin amount of the golf ball b also changes.
Specifically, in the back spin state shown in FIG. 5B, the spin amount is the same as the spin amount shown in FIG. 5A, but in the intermediate spin state shown in FIG. The apparent spin amount is smaller than the spin amount of 5 (c).
Further, in the side spin state shown in FIG. 5F, the apparent spin amount appears to be smaller than that in FIG.
In other words, the second spin amount SPB measured using the second antenna 14b decreases as the direction of the rotation axis M of the golf ball b approaches the vertical direction from the horizontal direction.

Therefore, there is a correlation between the difference ΔSP between the first spin amount SPA and the second spin amount SPB and the angle formed by the rotation axis M with the horizontal plane, and the direction of the rotation axis M (angle relative to the horizontal plane) is calculated from the difference ΔSP. can do.
In the present embodiment, the spin amount calculation unit 38 calculates the first spin amount SPA and the second spin amount SPB, and the spin amount calculation unit 38 calculates the difference ΔSP between the first spin amount SPA and the second spin amount SPB. Based on the above, the direction of the rotation axis M is obtained.
Further, as shown in FIGS. 5A to 5D, the first spin amount SPA measured by using the fourth antenna 14d indicates the actual spin amount of the golf ball b. A spin amount SPA of 1 is obtained as an actual measurement value of the spin amount of the golf ball b.

The analysis unit 34 performs frequency analysis on each intermediate data stored in the storage unit 30 using an FFT, so that the first signal intensity distribution data to the fourth signal indicating the distribution of the signal intensity for each frequency. Intensity distribution data is created.
For example, like the example of the second signal intensity distribution data shown in FIG. 7, by performing frequency analysis on the time waveform α of the second Doppler signal Sd2 corresponding to the second intermediate data shown in FIG. 6 by FFT, Second signal intensity distribution data β indicating the distribution of signal intensity for each frequency is obtained. In FIG. 7, the horizontal axis represents frequency (Hz), and the vertical axis represents signal intensity (arbitrary unit). In the signal intensity distribution data β, the frequency region β ₁ is derived from the movement of the golf club head, and the frequency region β ₂ is derived from the movement of the golf ball.

The above-mentioned frequency regions β ₁ and β ₂ can be obtained by fd = 2fc · V ₀ / c. Here, fd is a Doppler frequency (Hz), and fc is a carrier frequency (Hz). V ₀ is the speed (m / s) of the golf ball or golf club head. c is the speed of light (3 × 10 ⁸ m / s).
When the initial velocity of the golf ball is 50 m / s, fd is about 8000 Hz. For this reason, the region β ₂ of the frequency derived from the movement of the golf ball is about 8000 Hz. Here, in this embodiment, since the other thing to move is the golf club head, the region β _{1 having} a frequency around 4000 Hz is derived from the movement of the golf club head.
Various known FFT methods can be used for the FFT used in the analysis unit 34.
Hereinafter, the first signal intensity distribution data to the fourth signal intensity distribution data are referred to as each signal intensity distribution data.

The analysis unit 34 also performs moving average processing on each signal intensity distribution data to create moving average waveform data. For example, the moving average waveform data γ shown in FIG. 7 is obtained by performing the moving average process on the signal intensity distribution data β shown in FIG.
Since the signal intensity distribution data β is an actual measurement value, it greatly fluctuates due to the influence of noise included in the measurement. Therefore, by performing the moving average processing, signal intensity distribution data in which the influence of noise is suppressed, that is, moving average waveform data γ is obtained.

The moving speed calculator 36 calculates the moving direction and moving speed of the golf ball b based on each signal intensity distribution data.
Hereinafter, a method of calculating the moving speed of the golf ball b by the moving speed calculating unit 36 will be described using the moving average waveform data γ shown in FIG. 7 as an example. In the signal intensity distribution data, since the frequency region β ₂ derived from the golf ball b is known, the frequency region β ₂ derived from the golf ball b is analyzed.

FIG. 8 shows the signal intensity distribution data by enlarging the frequency region β ₂ derived from the golf ball b. The moving average waveform data γ shown in FIG. 8 has one maximum value in which the signal intensity is maximum in the frequency region β ₂ , and the signal intensity gradually decreases as the distance from the maximum value increases, and eventually becomes zero. It shows a single Yamagata signal intensity distribution. That is, there is a mountain shape at a portion where the signal intensity changes include the maximum value Dmax of the signal intensity in the region beta ₂ frequency.
Here, the peak height of the signal intensity distribution data, that is, the maximum value Dmax of the signal intensity corresponds to the above-described first speed VA (see FIG. 4). Therefore, in the frequency region β ₂ , the higher the maximum value Dmax of the signal strength, the faster the first speed VA, that is, the moving speed of the golf ball b.

The width of the peaks of the signal intensity distribution data, i.e., in the region beta ₂ frequency, frequency difference in a portion mountain-like signal strength changes, the above second speed VB of the aforementioned third speed VC It is proportional to the difference ΔV (speed range). For this reason, the smaller the difference ΔV between the second speed VB and the third speed VC, the smaller the spin amount. If the difference ΔV is zero, the spin amount is zero. Also, the greater the difference ΔV between the second speed VB and the third speed VC, that is, the greater the frequency difference, the greater the amount of spin.

Here, the difference ΔV between the second speed VB and the third speed VC is represented by the following expression (6) as can be seen from the expressions (4) and (5), that is, a value proportional to the angular speed ω. .
ΔV = VC−VB = (VA + ωr) − (VA−ωr) = 2ωr (6)
Therefore, as apparent from the equation (6), the spin amount can be calculated based on the width of the peak of the signal intensity distribution data.

In the present embodiment, the above-described peak width with a large amount of spin, that is, the frequency difference at the portion where the signal intensity changes in a mountain shape in the frequency region β ₂ can be defined as follows.
The width of the peak of the signal intensity distribution data is the width of the portion where the signal intensity becomes the threshold value Dt in the frequency region β ₂ when the signal intensity threshold value Dt is Dmax · n (where 0 <n <1). . That is, the signal intensity in the area beta ₂ of the frequency is the frequency difference between the threshold Dt.

FIG. 8 illustrates Dt ₂ = Dmax · 10% and Dt ₁ = Dmax · 50%. In this case, the frequency difference in the threshold Dt ₁ is [Delta] V _1, the difference in frequency in the threshold Dt ₂ is [Delta] V _2.
The threshold Dt may be set to a value that can stably measure the peak width (frequency difference), that is, the difference ΔV between the second speed VB and the third speed VC. In this way, by analyzing the signal intensity distribution data β shown in FIGS. 7 and 8, the moving speed V and the spin amount can be easily obtained.

In the present embodiment, the analysis unit 34 performs frequency analysis on each intermediate data stored in the storage unit 30 using FFT.
In the time waveform of the Doppler signal, the reflected wave of the golf head is mainly before the impact, and the reflection of the golf ball is mainly after the impact. Further, the spin amount of the golf ball is calculated based on the difference in frequency (mountain width) in the region β ₂ resulting from the movement of the golf ball. For this reason, in the analysis part 34, it is necessary to perform the time change in area | region (beta) ₂ derived from the movement of a golf ball in a high precision and a short time, maintaining frequency resolution before and after impact.

In the present invention, it has been found that if the ratio of measurement data is at least 20% of the number of analysis data, the frequency analysis by FFT analysis is not adversely affected.
As described above, according to the analysis method of the present invention, analysis can be performed with the frequency resolution maintained before and after the impact, so that the reflected waves of the golf head and the golf ball can be easily distinguished. Furthermore, since the ratio of measurement data can be reduced during the FFT analysis, the signal intensity distribution data β can be obtained in a short time while maintaining the frequency resolution. Thereby, the moving speed V and the spin amount can be calculated in a short time.

    The relationship between the sampling frequency and the frequency resolution is expressed by the following equation (7) when the sampling frequency is fs (Hz), the frequency resolution is Δf (Hz), and the number of sampling data is N (pieces). From this equation (7), it can be seen that the frequency resolution Δf does not decrease unless N of the number of sampling data is increased.

  Further, a time T (second) necessary for sampling is represented by the following formula (8). From this equation (8), a certain time T (second) is required to secure a predetermined frequency resolution Δf.

However, when measuring the change in spin amount at short time intervals, such as measuring the spin amount of a golf ball, it is necessary to shorten T while ensuring the frequency resolution Δf. In this case, it is assumed that T = T ₁ + T ₂ and the frequency resolution Δf is secured and analyzed even for short time data. T ₁ is actual measurement data, and T ₂ is 0 (zero) data. Specifically, the measured data is used for at least 20% of the number of FFT analysis data (the number of sampling data) N, and the other data is 0.

When the sampling frequency fs is constant, the necessary frequency resolution Δf is first determined as the frequency analysis procedure by FFT. Next, the FFT analysis data number N _f represented by N _f = fs / Δf is determined. Next, a time interval T necessary for the FFT analysis represented by T = N _f / fs is determined.
Next, among the FFT analysis data number _{N f,} for at least 20%, using the measured data, the remaining data as 0, it performs the FFT analysis.

In the present embodiment, the frequency decomposition and the ratio of measured data were examined for a time waveform based on the following conditions. Incidentally, E _a shown below is represented by the time waveform 40 shown in Figure 9 (a).

E _a = E ₁ + E ₂
E ₁ = 0.5 · cos (2πf ₁ · t), f ₁ = 5,000 Hz
E ₂ = 0.3 · cos (2πf ₂ · t), f ₂ = 5,015 Hz

Moreover, FFT was performed on the analysis conditions shown below. Assuming that fs = 48,000 Hz and N = 1,384 (2 ¹⁴ ), Δf≈2.93 Hz and T≈342 (msec).
In the FFT analysis, the time of the actual data T _{1 is} sequentially shortened from T ₁ = T to T ₁ = T / 100, that is, the proportion of the measured data is reduced in the FFT analysis data number N _f . , to verify whether it is possible to decomposition of _{E 1} and _{E 2.} That is, it is verified whether f ₁ and f ₂ can be separated. The result is shown in FIG. Note that f ₁ and f ₂ are about 5 lines apart by Δf.
As shown in FIG. 9B, if the measured data is 20% or more with respect to the FFT analysis data number N _f , f ₁ and f ₂ can be separated.

In addition, the frequency decomposition and the ratio of measurement data were examined for a time waveform in which only the frequency was changed with the above conditions. In addition, _Eb shown below is represented by the time waveform 50 shown to Fig.10 (a).

E _b = E ₃ + E ₄
E ₃ = 0.5 · cos (2πf ₃ · t), f ₃ = 5,000 Hz
E ₄ = 0.3 · cos (2πf ₄ · t), f ₄ = 5,115 Hz

In this case, f ₃ and f ₄ are 39 lines apart by Δf. As shown in FIG. 10B, when the actually measured data is 20% or more with respect to the FFT analysis data number N _f , f ₃ and f ₄ can be separated.
As described above, when performing FFT analysis, it with 20% of the data only measured data to the FFT analysis data number N _f, which does not cause significant differences in the remaining 80% is also FFT analysis result by applying a 0 (However, when only 1 / m data is used with respect to the original time data of FFT analysis, the amplitude spectrum of the FFT analysis result needs to be multiplied by m).

  Note that when the time axis data is cut out during the FFT analysis, the side lobe can be reduced by using a filter with a slope. In this case, when cutting 20% of the entire data, it is preferable to use a filter having a characteristic of becoming zero at 2.5% on both sides in addition to the 20% data. This filter is substantially trapezoidal if illustrated.

  The moving speed calculation unit 36 calculates the speed of the golf ball at the antennas 14a to 14d based on the maximum value Dmax in each signal intensity distribution data. Further, the moving speed calculation unit 36 calculates the moving direction Db of the golf ball b based on the speed of the golf ball in each of the antennas 14a to 14d.

A method of calculating the moving direction Db of the golf ball b will be described with reference to FIGS. 3 (a) and 3 (b). 3A and 3B, the symbol Db indicates the moving direction of the golf ball b, the reference line L01 indicates a reference line passing through the center O of the golf ball b and parallel to the target line L0. G indicates the ground parallel to the horizontal plane. Reference sign θx is an angle formed between the movement locus of the golf ball b and the reference line L01 when the movement locus of the golf ball b and the reference line L01 are projected onto the horizontal plane in a plan view. Hereinafter, the angle θx is referred to as a left-right angle.
Reference sign θy is an angle formed by the movement locus of the golf ball b and the reference line L01 when the movement locus of the golf ball b and the reference line L01 are projected onto a vertical plane including the reference line L01 in a side view. . Hereinafter, the angle θy is referred to as a vertical angle.

First, the golf ball b positioned at the origin is hit with a dedicated golf ball launching device (launcher) with different left and right angles θx and up and down angles θy.
Then, the horizontal angle θx and the vertical angle θy of the golf ball b are measured based on the image data of the golf ball b taken by the high-speed camera, and actual measurement data of the horizontal angle θx and the vertical angle θy are acquired. The measurement of the behavior of the golf ball b by such a high speed camera is conventionally known.

Simultaneously with the measurement of the left-right angle θx and the up-down angle θy, the speed of the golf ball at the antennas 14a to 14d is acquired by the moving speed calculation unit 36 using the measuring apparatus 10 of the present embodiment. That is, the golf ball speed corresponding to the measured data of the left-right angle θx and the vertical angle θy is acquired.
Then, an angle calculation map (an angle calculation data table) that associates the measured data of the left and right angles θx and the vertical angle θy with the velocity of the golf ball is created. This angle calculation map (angle calculation data table) is stored in the storage unit 30, for example.
By using the angle calculation map (angle calculation data table), the left and right angles θx and the vertical angle θy can be obtained from the velocity of the golf ball in the antennas 14a to 14d.

In the present embodiment, the moving speed calculation unit 36 calls the angle calculation map from the storage unit 30, and the moving speed calculation unit 36 uses the angle calculation map to change the left and right sides of the golf balls from the antennas 14 a to 14 d. The angle θx and the vertical angle θy can be calculated as the moving direction Db of the golf ball b.
The angle calculation map (angle calculation data table) is not limited to being stored in the storage unit 30.

Moreover, as a method of calculating the moving direction Db of the golf ball b by the moving speed calculation unit 36, the following may be performed in addition to using the angle calculation map.
For example, based on the measured data of the left and right angle θx and the vertical angle θy and the speed of the golf ball in the antennas 14a to 14d, a regression equation is derived using a conventionally known method such as a least square method, For example, the regression equation is stored in the storage unit 30. The moving speed calculation unit 36 may call this regression equation from the storage unit 30 and calculate the left / right angle θx and the up / down angle θy from the velocity of the golf ball in the antennas 14a to 14d based on the regression equation.

Further, the moving speed calculation unit 36 moves the moving speed V in the moving direction of the golf ball b based on one of the speeds of the golf balls in the antennas 14a to 14d and the moving direction Db of the golf ball b (FIG. 3). (A) and FIG. 3 (b)) are calculated.
Specifically, by obtaining an angle φ formed by the trajectory trajectory in the three-dimensional space of the golf ball b specified by the left and right angle θx and the vertical angle θy and the reference line L01, the moving speed V is expressed by the following equation (9). Is calculated.

  V = VA · cosφ (9)

The spin amount calculation unit 38 calculates the spin amount and spin direction (direction) of the golf ball. The spin amount calculation unit 38, as described above, and calculates a spin rate based on the difference between the frequency of the portion of the mountain shape on the signal strength in the region beta ₂ frequency changes.
Specifically, the spin amount calculation unit 38, based on the difference in the frequency of the fourth signal intensity distribution ₂ region of the frequency β in the data to calculate the first spin amount SPA golf ball b, the second and it calculates the second spin rate SPB golf ball b on the basis of the difference between the frequencies of the signal intensity distribution ₂ region of the frequency β in the data. As described above, the first spin amount SPA is an actual measurement value of the spin amount of the golf ball b.
The spin amount calculation unit 38 further calculates the direction of the rotation axis of the golf ball b based on the difference ΔSP between the first spin amount SPA and the second spin amount SPB.

The display unit 24 has a display screen that displays the numerical value of the moving speed and spin amount of the golf ball b, the moving direction, the spin direction (direction), and the like calculated by the arithmetic processing unit 20.
Instead of the display unit 24 or in addition to the display unit 24, a printer that prints out the numerical values of the moving speed and the spin amount, the moving direction, and the spin direction (direction) may be provided as the output unit. Further, in place of or in addition to the display unit 24, there is provided a communication circuit for supplying numerical values of the moving speed and spin amount, the moving direction, and the spin direction (direction) to an external device such as a personal computer. It may be provided.

  For example, the operation unit 26 inputs various instructions in order to switch a display form such as a numerical value of the moving speed and spin amount of the golf ball b displayed on the display unit 24, a moving direction, and a spin direction (direction). Is to do. The instruction input by the operation unit 26 is supplied to the CPU 22 and controls each element so as to perform an operation according to the instruction input from the CPU 22.

In the present embodiment, the spin amount SP in the case of back spin is represented by a positive value for the spin amount in the reverse rotation direction and a negative value for the spin amount in the forward rotation direction, for example.
In the present embodiment, the spin amount SP in the case of side spin is, for example, a positive value for the spin amount in the clockwise direction in plan view and a negative value for the spin amount in the counterclockwise direction.

Here, FIG. 11 is a graph showing the actual measurement results of the spin amount SP and the difference ΔSP of the golf ball being back-spun, and FIG. 12 is the actual measurement of the spin amount SP and the difference ΔSP of the side-spinning golf ball. It is a graph which shows a result. Note that the unit of the difference ΔSP is an arbitrary unit. Further, the points plotted in FIGS. 11 and 12 indicate actual measurement values, and the straight line H ₁ shown in FIG. 11 and the straight line H ₂ shown in FIG. 12 are based on regression equations obtained from the actual measurement values. As shown in FIGS. 11 and 12, the difference ΔSP and the spin amount SP have a correlation.

Next, the golf ball b used for the ball measuring device 10 of this embodiment will be described.
FIG. 13A is a schematic diagram showing an example of a golf ball used in the ball measuring device according to the embodiment of the present invention, and FIG. 13B shows a golf ball used in the ball measuring device according to the embodiment of the present invention. It is a schematic diagram which shows another example.
As shown in FIG. 13A, the golf ball b includes a sphere 202, a first region 204, and a second region 206.
The spherical body 202 is formed of a solid and spherical core layer and a cover layer made of a synthetic resin that covers the core layer, and a large number of dimples (not shown) are formed on the surface of the cover layer.

The first region 204 is a region having a high radio wave reflectance formed on a spherical surface centered on the center of the sphere 202. As described above, the first region 204 has high radio wave reflection characteristics, and efficiently reflects radio waves (microwaves).
In the present embodiment, a plurality of first regions 204 are formed on the surface of the sphere 202 (on the surface of the cover layer) and have conductivity.
In addition, each first region 204 has a perfect circle shape having the same diameter, but the shape of each first region 204 may be a triangle, a quadrangle, or a regular polygon.

When each first region 204 is a perfect circle, the diameter of the perfect circle is preferably 2 mm or more and 15 mm or less in order to ensure the intensity of the reflected wave and to ensure the measurement accuracy in the measurement apparatus 10.
Moreover, when each 1st area | region 204 is a regular polygon, in order to ensure the intensity | strength of a reflected wave and to ensure the measurement precision in the measuring device 10, the diameter of the inscribed circle shall be 2 mm or more and 15 mm or less. Is preferred.

In addition, when the diameter of a perfect circle or an inscribed circle is 2 mm or more and 15 mm or less, it is advantageous in securing measurement accuracy that the inventors of the present invention use a 24 GHz or 10 GHz microwave as a transmission wave. This is confirmed by the experimental results. This is considered to be because, for example, the influence of interference between the reflected wave reflected at the surface of the first region 204 and the reflected wave reflected at the edge portion of the first region 204 on measurement accuracy is reduced. It is done.
Further, as shown in FIG. 13A, on the spherical surface (on the surface of the sphere 202 in the present embodiment), two points passing through the first region 204 facing each other and the center of the sphere 202 are provided. The angle θ formed by the straight line is preferably 5 degrees or more and 45 degrees or less in order to obtain a reflected wave with sufficient intensity and to receive the reflected wave with high accuracy.

The plurality of first regions 204 are located at the vertices of a regular polyhedron or quasi-regular polyhedron that is assumed to be located on the surface of the sphere 202 (a spherical surface centered on the center of the sphere 202).
For example, in the case shown in FIG. 13A, the first region 204 is located at six vertices of a regular hexahedron that is assumed to be located on the surface of the sphere 202. Therefore, six first regions are formed.

  In another example shown in FIG. 13B, for example, the first region 204 is located at four vertices of a regular tetrahedron so that the vertex is located on the surface of the sphere 202. Four regions are formed. A plurality of the first regions 204 may be formed on the surface of the sphere 202, and the number thereof is not limited to four and is arbitrary.

  However, the first region 204 can stably reflect the transmission wave W1 while moving (rotating) as many first regions 204 as possible regardless of the direction of the rotation axis of the sphere 202. This is preferable for obtaining the reflected wave W2.

The plurality of first regions 204 may extend in a straight line perpendicular to each other on the surface of the sphere 202 and may have a lattice shape.
In this case, the second region 206 is partitioned into a rectangular shape by the first region 204 extending linearly.

The first region 204 only needs to be able to sufficiently secure the intensity of the reflected wave W2. For example, a range necessary for the surface resistance of the first region 204 is obtained by using a conventionally known relational expression shown below. Can do.
That is, when the radio wave reflectance is Γ and the surface resistance is R, Expressions (10) and (11) are established.

Γ = (377−R) / (377 + R) (10)
R = (377 (1-Γ)) / (1 + Γ) (11)

  Note that Γ = 1 indicates total reflection, Γ = 0 indicates no reflection, and 377 indicates the characteristic impedance of air. From equation (11), R = 0 when Γ = 1, and R = 377 when Γ = 0.

Here, when Γ = 0.5, R = (377 × 0.5) /1.5≈130.
Therefore, if a sufficient value for the radio wave reflectance Γ is Γ = 0.5 (50%) or more, the surface resistance R is 130Ω / sq. It is necessary to:
Further, the radio wave reflectance Γ is 0.9 (90%) or more, and therefore the surface resistance R is 20 Ω / sq. The following is more preferable in securing the intensity of the reflected wave W2.
The radio wave reflectance Γ can be measured by a conventionally known method such as a waveguide method or a free space method.

As a material constituting the first region 204, a conductive material can be used.
The conductive material is, for example, a paint containing metal powder. By applying or printing such a paint on the surface of the sphere 202, the first region 204 is formed.
As such a paint, various conventionally known paints can be used, for example, a rust preventive paint containing zinc is used.

In addition, the conductive material may be a metal foil. The first region 204 is formed by sticking such a metal foil to the surface of the sphere 202 with an adhesive.
As such a metal foil, various conventionally known metal foils such as an aluminum foil can be used.
Alternatively, the first region 204 may be formed of a vapor deposition film or a discontinuous vapor deposition film formed by vapor deposition of a conductive material.

  In addition, the discontinuous vapor deposition film is formed by discontinuous vapor deposition performed in a vacuum. The discontinuous vapor deposition film is a stage in which the growth nuclei do not contact each other in the process in which the atoms evaporated from the target adhere to the surface of the sphere 202 as the vapor deposition target and a plurality of growth nuclei grow, in other words, the respective growth nuclei. It is a vapor deposition film in a state where vapor deposition is stopped when the layers are not continuous and the growth nuclei are not electrically connected. Therefore, in the discontinuous vapor deposition film, the growth nuclei are not electrically connected to each other and are non-conductive, but have radio wave reflectivity.

Moreover, as a metal which forms the metal powder or metal foil mentioned above or a vapor deposition film, various conventionally well-known metals, such as silver, copper, gold | metal | money, nickel, aluminum, iron, titanium, tungsten, can be used, for example.
In addition, as a material having conductivity, various conventionally known materials such as a conductive substance other than metal, for example, a material containing carbon can be used.

The second region 206 is a region formed on the remaining portion of the spherical surface excluding the first region 204 and having a radio wave reflectance lower than that of the first region 204.
In other words, the second area 206 has a radio wave reflection characteristic lower than that of the first area 204.
In the present embodiment, the second region 206 is formed on the remaining surface portion excluding the first region 204 (on the remaining surface portion of the cover layer excluding the first region 204) and has no conductivity.

In the present embodiment, the second region 206 is formed of a synthetic resin that forms the surface of the golf ball b.
In order to secure a large ratio (difference) between the radio wave reflectivity of the first region 204 and the radio wave reflectivity of the second region 206, the radio wave reflectivity of the second region 206 is 1% or less and the surface resistance is 400Ω / sq. . The above is preferable.

The total area of the first region 204 is preferably 50% or less of the surface area of the sphere 202, and more preferably 2% to 30%.
When the total area of the first region 204 is 50% or less of the surface area of the sphere 202, the ratio between the reflection intensity of the radio wave reflected by the first region 204 and the reflection intensity of the radio wave reflected by the second region 206 ( It is advantageous to ensure a large (difference), and 2% to 30% is more advantageous to ensure a large ratio (difference) in the reflection intensity.
Thus, securing a large ratio (difference) between the reflection intensities in the first region 204 and the second region 206 is advantageous in stably measuring the spin rate.

In the present embodiment, the case where the first and second regions 204 and 206 are formed on a spherical surface centered on the center of the sphere 202 has been described.
However, the surface on which the first and second regions 204 and 206 are formed is not limited to the outer surface, and may be inside the sphere 202. In this case, a surface forming a spherical surface or a regular polyhedron. In other words, it may be a surface forming a quasi-regular polyhedron. In short, when the sphere 202 rotates, the first and second regions 204 and 206 rotate, and the first and second regions 204, 206 may be directed alternately.
As described above, the golf ball b only needs to have the first region 204 having radio wave reflectivity and the second region 206 having a radio wave reflectivity lower than that of the first region 204.

Next, a method for measuring the behavior of the golf ball b by the ball measuring device 10 will be described.
First, when the golfer grips and swings the golf club 100 and launches the golf ball b with the golf club head 102, the behavior of the golf ball by the ball measuring device 10 is measured.
Specifically, the transmission waves W1 are transmitted from the antennas 14a to 14d toward the golf ball b, respectively, and the reflected waves W2 from the golf ball b are received by the antennas 14a to 14d. When the reflected wave W2 is received by each of the antennas 14a to 14d, a reception signal is generated. Then, each received signal is supplied to Doppler sensors 16a to 16d, and Doppler frequencies Fd1 to Fd4 are created by Doppler sensors 16a to 16d, respectively, and Doppler frequencies Fd1 to Fd4 are obtained (step S10).

  The Doppler signals Sd1 to Sd4 are converted into digital data (binarized signals) by the signal processing units 18a to 18d, and then converted to digital data (binary signals) by the detection unit 28 to the intermediate data associated with the Doppler frequencies Fd1 to Fd4. These converted intermediate data are sampled and then stored in the storage unit 30 as time-series data.

Next, the analysis unit 34 performs frequency analysis on each piece of intermediate data stored in the storage unit 30 (step S12). Thereby, each signal intensity distribution data which shows distribution of signal intensity for every frequency is created.
Hereinafter, regarding the method of creating the first signal intensity distribution data, description of the remaining second signal intensity distribution data to fourth signal intensity distribution data will be omitted, but the remaining second signal intensity distribution data to The signal intensity distribution data 4 can be created in the same manner as the first signal intensity distribution data.

In this case, the time waveform α of the Doppler signal Sd1 shown in FIG. 15 corresponds to the first intermediate data. The time waveform α of the Doppler signal Sd1 shown in FIG. 15 has, for example, a total measurement time of 200 (msec) and an FFT analysis data number (sampling data number) of 8129.
In this time waveform α, FFT analysis is performed by dividing it into 9 sections (i) to (ix) at intervals of 20 (msec) with 40 (msec) and the number of data 2000 as one section unit. That is, out of the FFT analysis data number 8129, the actual measurement data is used for 2000 data, the remaining data is set to 0, and the actual measurement data is shifted in the area of the actual measurement data under the condition that the ratio is about 25%. Do. As a result, the signal intensity distribution data shown in FIGS. 16A to 16D and FIGS. 17A to 17E are obtained.
Each of the signal intensity distribution data shown in FIGS. 16A to 16D and FIGS. 17A to 17E corresponds to nine sections (i) to (ix) shown in FIG.

As shown in FIG. 16 (a), first, a region beta ₁ of the signal intensity derived from the golf club head is increased, then, as shown in FIG. 16 (b), a region beta ₂ derived from the movement of the golf ball The signal strength of becomes higher. Then, as shown in FIG. 16 (c), (d) , with the golf club head is a region beta ₁ of the signal intensity derived from the decreases, the signal intensity of a region beta ₂ derived from the movement of the golf ball is increased. Thereafter, as shown in FIG. 17 (a), a region beta ₁ of the signal intensity derived from the golf club head is extremely small, also becomes small signal intensity of a region beta ₂ derived from the movement of the golf ball. Then, as shown in FIG. 17 (b), the signal intensity of a region beta ₂ derived from the movement of the golf ball becomes extremely small, further, as shown in FIG. 17 (c) ~ (e) , the golf club In both the region β ₁ from which the head originates and the region β ₂ from the movement of the golf ball, the signal intensity is hardly detected. Thus, the golf region beta ₂ of the signal derived from the movement of the ball upon hitting a golf ball, can be detected separately from the golf club head.

  Next, the moving speed calculation unit 36 performs a moving average process on each signal intensity distribution data to calculate the maximum value Dmax, and calculates the speed of the golf ball at the antennas 14a to 14d based on the maximum value Dmax. (Step S14).

Next, the moving speed calculation unit 36 calculates the moving direction Db of the golf ball b based on the golf ball speed at the antennas 14a to 14d (step S16).
Next, in the moving speed calculation unit 36, the moving speed V in the moving direction Db of the golf ball b is calculated based on any one of the speeds of the golf balls in the antennas 14a to 14d and the moving direction Db of the golf ball b. Calculate (step S18).

Next, the spin amount calculating section 38, based on the difference in the frequency of the fourth signal intensity distribution ₂ region of the frequency β in the data to calculate the first spin amount SPA golf ball b, a second signal strength calculating a second spin rate SPB golf ball b on the basis of the difference between the frequencies in the frequency region beta ₂ in the distribution data (step S20). Further, the spin amount calculation unit 38 calculates the direction of the rotation axis M of the golf ball b based on the difference ΔSP between the first spin amount SPA and the second spin amount SPB (step S22). As described above, the first spin amount SPA is an actual measurement value of the spin amount of the golf ball b.

Finally, the calculated movement speed V, movement direction Db, spin amount SP, and direction of the rotation axis M are displayed on the display screen of the display unit 24 (step S24).
When displaying on the display screen of the display unit 24, for example, the moving direction Db of the golf ball b is the horizontal angle θx, the unit of the vertical angle θy is (degrees), the unit of the moving speed V is (m / s), and the spin amount The unit of SP is displayed as (rpm). In addition, the display method of the moving direction Db is not specifically limited.

When displaying on the display screen of the display unit 24, for example, for the left and right angle θx, the reference line L01 is the center (0 degree), the left angle is a positive value, the right angle is a negative value, With respect to the vertical angle θy, the reference line L01 is the center (0 degree), the upward angle can be indicated as a positive value, and the downward angle as a negative value. The positive and negative signs may be opposite to those described above. Further, the spin amount SP in the case of backspin can be represented by, for example, a positive value for the spin amount in the reverse rotation direction and a negative value for the spin amount in the forward rotation direction.
The spin amount SP in the case of side spin can be represented, for example, by a positive value for the spin amount in the clockwise direction in plan view and a negative value for the spin amount in the counterclockwise direction. As described above, the difference ΔSP and the spin amount SP are correlated as shown in FIGS.

  In the ball measuring apparatus 10 and the measuring method according to the present embodiment, the golf club is obtained by performing FFT analysis by assigning 0 to the remaining data with the ratio of the measured data being at least 20% of the number of FFT analysis data. The frequency representing the behavior of the head and the golf ball can be separated, and furthermore, sufficient resolution can be obtained for the region derived from the movement of the golf ball for calculating the moving speed and the spin rate. Therefore, the moving speed and the spin amount can be calculated. In addition, since the substantial number of data required for the analysis is small, the processing speed of the FFT analysis can be increased. Thereby, the time required for calculating the moving speed and the spin amount can be shortened. Therefore, the time required for calculating the moving speed V, the moving direction Db, the spin amount SP, and the direction of the rotation axis M of the golf ball b can be shortened.

In the present embodiment, four antennas are provided. However, the present invention is not limited to this, and one antenna may be provided. Even in this case, the moving speed and spin amount of the golf ball can be calculated, and the time required for calculating the moving speed and spin amount of the golf ball can be shortened.
Furthermore, in the present embodiment, the golf ball has been described as an example. However, the present invention is not limited to the golf ball, and the movement speed and movement are not limited to the ball for ball games such as a baseball ball, a soccer ball, and a volleyball ball. It is possible to measure the direction, the spin amount, the direction of the rotation axis, and the like.

  The present invention is basically configured as described above. Although the ball measuring device and the ball measuring method of the present invention have been described in detail above, the present invention is not limited to the above-described embodiment, and various improvements or modifications may be made without departing from the spirit of the present invention. Of course.

DESCRIPTION OF SYMBOLS 10 Ball measuring device 14a-14d 1st antenna-4th antenna 16a-16d 1st Doppler sensor-4th Doppler sensor 18a-18d 1st signal processing part-4th signal processing part 20 Arithmetic processing unit 22 CPU
24 display section 26 operation section 28 detection section 30 accumulation section 32 behavior calculation section 34 analysis section 36 movement speed calculation section 38 spin amount calculation section b golf ball

Claims (8)

A transmission wave is transmitted based on a supplied transmission signal toward a ball having a first region having radio wave reflectivity and a second region having a radio wave reflectivity lower than that of the first region, and reflected by the ball. A first antenna to a fourth antenna that receive the reflected wave and generate a reception signal;
The transmission signal is supplied to each of the first antenna to the fourth antenna, and the Doppler frequency is based on the reception signals supplied from the first antenna to the fourth antenna. A first Doppler sensor to a fourth Doppler sensor for creating a signal;
The first signal intensity indicating the distribution of the signal intensity for each frequency by performing frequency analysis on each of the first Doppler signal to the fourth Doppler signal created by the first Doppler sensor to the fourth Doppler sensor. An analysis unit for creating distribution data to fourth signal intensity distribution data;
A moving speed calculation unit that calculates a moving speed and a moving direction of the ball based on the first signal intensity distribution data to the fourth signal intensity distribution data;
A spin amount calculation unit that calculates the spin amount of the ball based on the first signal intensity distribution data to the fourth signal intensity distribution data;
When the frequency analysis of the first Doppler signal to the fourth Doppler signal is performed, the analysis unit includes at least the total number of analysis data for each of the first Doppler signal to the fourth Doppler signal. The first Doppler signal to the fourth Doppler signal are used for 20% of data, and the remaining data is set to 0.
The first to fourth antennas are configured by directional antennas, are provided on the opposite side to the moving direction of the ball, and the first to third antennas are provided. The second antenna is arranged centering on the second antenna at a predetermined interval in the horizontal direction, and the fourth antenna is arranged above the second antenna at a predetermined interval in the vertical direction. Ball measuring device. The analysis unit further performs a moving average process on the first signal intensity distribution data to the fourth signal intensity distribution data to generate first moving average waveform data to fourth moving average waveform data. Is what
The moving speed calculation unit calculates the maximum value of the signal intensity in the frequency domain derived from the movement of the ball for each of the first moving average waveform data to the fourth moving average waveform data, 2. The ball measuring device according to claim 1 , wherein a moving speed and a moving direction of the ball are calculated based on the maximum values of the first moving average waveform data to the fourth moving average waveform data. 3. The second antenna has a first virtual axis indicating a directivity direction extending in the horizontal direction, and the fourth antenna has a second virtual axis indicating directivity intersecting the first virtual axis. Has been placed,
The analysis unit further performs a moving average process on the second signal intensity distribution data and the fourth signal intensity distribution data to generate second moving average waveform data and fourth moving average waveform data. Is what
The spin amount calculation unit changes the waveform data of the second moving average and the waveform data of the fourth moving average in a mountain shape including the maximum value of the signal intensity in the frequency domain derived from the movement of the ball, respectively. And calculating a difference in frequency of the portion that changes in a mountain shape, calculating a spin amount of the ball based on the difference in frequency of the waveform data of the fourth moving average, and based on a difference between the difference of the frequency of the difference between the fourth moving average of the waveform data of the frequency of the second moving average of the waveform data, according to claim 1 to calculate the direction of the rotation axis of the ball Ball measuring device. The frequency difference is a frequency difference in a portion where the signal strength is the threshold value Dt when the maximum value of the signal strength is Dmax and the threshold value Dt is Dmax · n (where 0 <n <1). The ball measuring device according to claim 3 . A wave transmitted from a first antenna to a fourth antenna composed of directional antennas toward a ball having a first region having radio wave reflectivity and a second region having a radio wave reflectivity lower than the first region. And a reflected wave reflected by the ball is received by each of the first antenna to the fourth antenna to generate a received signal, and a first signal having a Doppler frequency is generated based on each received signal. Creating a Doppler signal to a fourth Doppler signal;
Generating first signal intensity distribution data to fourth signal intensity distribution data indicating a distribution of signal intensity for each frequency by performing frequency analysis on each of the first Doppler signal to the fourth Doppler signal; and ,
Calculating a moving speed and a moving direction of the ball based on the first signal intensity distribution data to the fourth signal intensity distribution data, and calculating a spin amount of the ball,
When frequency-analyzing the first Doppler signal to the fourth Doppler signal, at least 20% of the total number of analysis data for each of the first Doppler signal to the fourth Doppler signal Using the first Doppler signal to the fourth Doppler signal, the remaining data is set to 0,
The first to fourth antennas are provided on the side opposite to the moving direction of the ball, and the first to third antennas are arranged at a predetermined interval in the horizontal direction. And a fourth antenna is arranged above the second antenna at a predetermined interval in the vertical direction. The step of calculating the moving speed and the moving direction of the ball further performs a moving average process on the first signal intensity distribution data to the fourth signal intensity distribution data to obtain first moving average waveform data to Create 4 moving average waveform data,
For each of the waveform data of the first moving average to the waveform data of the fourth moving average, the maximum value of the signal intensity in the frequency domain derived from the movement of the ball is calculated, and the first moving average waveform data The ball measuring method according to claim 5 , wherein a moving speed and a moving direction of the ball are calculated based on the maximum values of waveform data to waveform data of the fourth moving average. The second antenna has a first virtual axis indicating a directivity direction extending in the horizontal direction, and the fourth antenna has a second virtual axis indicating directivity intersecting the first virtual axis. Has been placed,
The step of calculating the spin amount of the ball further includes moving average processing on the second signal intensity distribution data and the fourth signal intensity distribution data to obtain second moving average waveform data and fourth movement. Create average waveform data,
For the waveform data of the second moving average and the waveform data of the fourth moving average, calculate a portion that changes in a mountain shape including the maximum value of the signal intensity in the frequency domain derived from the movement of the ball, Calculate the difference in frequency of the portion that changes in a mountain shape, calculate the spin amount of the ball based on the difference in frequency of the waveform data of the fourth moving average,
Further, the direction of the rotation axis of the ball is calculated based on a difference between the frequency difference of the second moving average waveform data and the frequency difference of the fourth moving average waveform data. 5. The ball measuring method according to 5 . The frequency difference is a frequency difference in a portion where the signal strength is the threshold value Dt when the maximum value of the signal strength is Dmax and the threshold value Dt is Dmax · n (where 0 <n <1). The ball measuring method according to claim 7 .

Images