GOLF CLUB SHAFT FITTING METHOD

• US 20130260923A1
• Filed: 03/29/2013
• Published: 10/03/2013
• Est. Priority Date: 03/30/2012
• Status: Active Grant

• Current Assignee: Sumitomo Rubber Industries Limited
• Original Assignee: Dunlop Sports Co. Ltd. (Sumitomo Rubber Industries Limited), Sumitomo Rubber Industries Limited
• Inventors: OKAZAKI, Kousuke, UEDA, Masahiko, KATO, Masatoshi
• Granted Patent: US 9,452,331 B2
• Time in Patent Office: Days
• US Class Current: 473/409
• CPC Class Codes: A63B 60/42 Devices for measuring, verifying, correcting or customising the inherent characteristics of golf clubs, bats, rackets or the like, e.g. measuring the maximum torque a batting shaft can withstand
• CPC Class Codes: G01B 7/001 Constructional details of gauge heads G01B7/012 takes precedence

Abstract

A fitting method of a shaft of a golf club for selecting a shaft matching a golfer based on a swing of the golfer. The method includes the steps of obtaining measurement values from a sensor attached to a grip of a golf club; determining address, top, and impact of a swing from the measurement values; and selecting a shaft that matches a golfer through a usage of the swing characteristic amounts and values.

Claims

1. A fitting method of a shaft of a golf club for selecting a shaft matching a golfer based on a swing of the golfer, the method comprising the steps of:

obtaining measurement values from a sensor attached to a grip of a golf club and capable of measuring angular velocities about three axes when a golf ball is hit by the golf club;

determining address, top, and impact of a swing from the measurement values; and

selecting a shaft that matches a golfer through a usage of the following swing characteristic amounts of (a) to (d) obtained from the measurement values;

(a) Amount of change of grip angular velocity in a direction of a wrist cock around the top;

(b) An average value of grip angular velocity in the direction of a wrist cock, from the top to a point during a downswing where a grip angular velocity in the direction of a wrist cock becomes a maximum;

(c) An average value of grip angular velocity in the direction of a wrist cock, from a point during a downswing where a grip angular velocity in the direction of a wrist cock becomes a maximum to the impact;

(d) An average value of grip angular velocity in the direction of a wrist cock, from the top to the impact.

2. The fitting method of a shaft of a golf club according to claim 1, wherein the above described (a) to (d) are respectively selected so as to correspond to bending stiffnesses of the shaft at four positions of 36 inches, 26 inches, 16 inches, and 6 inches each from a tip end of the shaft;

an approximate expression that is created in advance with test-hitting and that represents a relationship between bending stiffnesses of the shaft and each of the swing characteristic amounts of (a) to (d), and the swing characteristic amounts of (a) to (d) obtained from the measurement values, are used to acquire bending stiffnesses of the shaft at four positions of 36 inches, 26 inches, 16 inches, and 6 inches from the tip end of the shaft; and

from multiple shafts whose bending stiffnesses are measured in advance at the four positions, a shaft matching a golfer is selected based on the acquired bending stiffnesses of the shaft at four positions.

3. The fitting method of a shaft of a golf club according to claim 2, wherein one rank value among multiple-scale rank values is given to each of the bending stiffnesses at the four positions in accordance with the acquired bending stiffness values;

and

a shaft matching a golfer is selected based on the given rank values at the four positions, from multiple shafts whose bending stiffnesses have been measured in advance at the four positions and that are each given one rank value among multiple-scale rank values in accordance with measured bending stiffness values.

4. The fitting method of a shaft of a golf club according to claim 2, wherein multiple approximate expressions are created in accordance with head speed.

5. The fitting method of a shaft of a golf club according to claim 2, wherein when a length of the golf club of a user is different from a length of a golf club having the shaft selected from multiple shafts, a total weight of the golf club is changed based on the difference of the two lengths.

6. A fitting method of a shaft of a golf club for selecting a shaft matching a golfer based on a swing of the golfer, the method comprising the steps of:

obtaining measurement values from a sensor attached to a grip of a golf club and capable of measuring angular velocities about three axes when a golf ball is hit by the golf club;

determining address, top, and impact of a swing from the measurement values; and

selecting a shaft that matches a golfer through a usage of at least two of the following swing characteristic amounts of (a) to (c) obtained from the measurement values, wherein

the above described (a) to (c) are respectively selected so as to correspond to bending stiffnesses of the shaft at three positions of 36 inches, 26 inches, and 6 inches each from a tip end of the shaft,

based on a relationship between bending stiffnesses of the shaft and each of the swing characteristic amounts of (a) to (c) created in advance with test-hitting, in each of the positions, each of the swing characteristic amounts is divided into multiple ranges, and bending-stiffness ranges of the shaft are configured so as to correspond to the respective ranges,

from the measurement values, the bending-stiffness ranges of the shaft are acquired at positions corresponding to the swing characteristic amounts at at least two positions among three positions of 36 inches, 26 inches, and 6 inches from the tip end of the shaft, and

from multiple shafts whose bending stiffnesses are measured in advance at the three positions, a shaft matching a golfer is selected based on the acquired bending-stiffness ranges of the shaft at least two positions;

(a) Amount of change of grip angular velocity in a direction of a wrist cock around the top;

(b) An average value of grip angular velocity in the direction of a wrist cock, from the top to a point during a downswing where a grip angular velocity in the direction of a wrist cock becomes a maximum;

(c) An average value of grip angular velocity in the direction of a wrist cock, from the top to the impact.

7. The fitting method of a shaft of a golf club according to claim 6, wherein one rank value among multiple-scale rank values is given to each of bending stiffnesses at the three positions in accordance with the acquired bending stiffness values;

and

a shaft matching a golfer is selected based on the given rank values at the three positions, from multiple shafts whose bending stiffnesses have been measured in advance at the three positions and that are each given one rank value among multiple-scale rank values in accordance with measured bending stiffness values.

8. The fitting method of a shaft of a golf club according to claim 6, wherein a classification of bending stiffness EI (N·

m²)<

68.5 is applied when the swing characteristic amount (a) is not larger than 360 (deg/s), and a classification of bending stiffness EI (N·

m²)>

60.0 is applied when the swing characteristic amount (a) is larger than 360 (deg/s);

a classification of bending stiffness EI (N·

m²)<

47.5 is applied when the swing characteristic amount (b) is not larger than 550 (deg/s), and a classification of bending stiffness EI (N·

m²)>

42.5 is applied when the swing characteristic amount (b) is larger than 550 (deg/s); and

a classification of bending stiffness EI (N·

m²)<

24.5 is applied when the swing characteristic amount (c) is not larger than 400 (deg/s), a classification of 23.0<

bending stiffness EI (N·

m²)<

27.5 is applied when the swing characteristic amount (a) is larger than 400 (deg/s) but not larger than 800 (deg/s), and a classification of bending stiffness EI (N·

m²)>

25.5 is applied when the swing characteristic amount (c) is larger than 800 (deg/s).

9. The fitting method of a shaft of a golf club according to claim 8, wherein upon selecting a shaft matching a golfer using the three swing characteristic amounts, when a shaft conforming to all the bending-stiffness ranges of the shaft acquired from each of the swing characteristic amount does not exist in the multiple shafts whose bending stiffnesses are measured in advance at the three positions corresponding to the three swing characteristic amounts;

selecting of a shaft is conducted in accordance with a priority order of;

a shaft conforming to a bending-stiffness range of a shaft acquired from the swing characteristic amount of (c), a shaft conforming to a bending-stiffness range of a shaft acquired from the swing characteristic amount of (a), and a shaft conforming to a bending-stiffness range of a shaft acquired from the swing characteristic amount of (b).

10. The fitting method of a shaft of a golf club according to claim 8, wherein upon selecting a shaft matching a golfer using the three swing characteristic amounts, when a shaft conforming to all the bending-stiffness ranges of the shaft acquired from each of the swing characteristic amount does not exist in the multiple shafts whose bending stiffnesses are measured in advance at the three positions corresponding to the three swing characteristic amounts;

selecting of a shaft is conducted in accordance with a priority order of;

a shaft conforming to a bending-stiffness range of a shaft acquired from the swing characteristic amount of (a), a shaft conforming to a bending-stiffness range of a shaft acquired from the swing characteristic amount of (b), and a shaft conforming to a bending-stiffness range of a shaft acquired from the swing characteristic amount of (c).

11. A fitting method of a shaft of a golf club for selecting a shaft matching a golfer based on a swing of the golfer, the method comprising the steps of:

obtaining measurement values from a sensor attached to a grip of a golf club and capable of measuring angular velocities about three axes when a golf ball is hit by the golf club, and measuring a face angle and an approach angle of a head of the golf club immediately before impact;

determining timing of top and impact of a swing from the measurement values; and

selecting a shaft that matches a golfer, through a usage of at least two swing characteristic amounts of the following (a) to (d) obtained from the measurement values, and the measured face angle and approach angle, wherein

a shaft suited for a golfer is preliminarily selected based on the measured face angle and approach angle and on a relation C created using a pre-created correlation R between a hit-ball result and face angle and approach angle immediately before impact, and then a shaft is selected with a usage of the swing characteristic amounts;

(a) Amount of change of grip angular velocity in a direction of a wrist cock around the top;

(b) An average value of grip angular velocity in the direction of a wrist cock, from the top to a point during a downswing where a grip angular velocity in the direction of a wrist cock becomes a maximum;

(c) An average value of grip angular velocity in the direction of a wrist cock, from a point during a downswing where a grip angular velocity in the direction of a wrist cock becomes a maximum to the impact;

(d) An average value of grip angular velocity in the direction of a wrist cock, from the top to the impact.

12. The fitting method of a shaft of a golf club according to claim 11, wherein the correlation R is based on hit-ball results of multiple golf clubs having different shaft kick point rates;

the relation C is a predetermined relational expression of a face angle and an approach angle immediately before impact and a shaft kick point rate created in advance; and

in the step of selecting, a shaft kick point rate is calculated using the relational expression from the face angle and the approach angle immediately before impact, and a shaft conforming to the calculated kick point rate is preliminarily selected from multiple shafts.

13. The fitting method of a shaft of a golf club according to claim 11, wherein the above described (a) to (d) correspond to bending stiffnesses of the shaft at four positions of 36 inches, 26 inches, 16 inches, and 6 inches each from a tip end of the shaft;

based on an approximate expression that is created in advance with test-hitting and that represents a relationship between bending stiffnesses of the shaft and each of the swing characteristic amounts of (a) to (d), from the swing characteristic amounts of (a) to (d) obtained from the measurement values, bending stiffness of the shaft is acquired at four positions of 36 inches, 26 inches, 16 inches, and 6 inches each from the tip end of the shaft; and

from multiple shafts whose bending stiffnesses are measured in advance at the four positions, a shaft matching a golfer is selected based on the acquired bending stiffnesses of the shaft at four positions.

14. The fitting method of a shaft of a golf club according to claim 13, wherein one rank value among multiple-scale rank values is given to each of the bending stiffnesses at the four positions in accordance with the acquired bending stiffness values;

and

a shaft matching a golfer is selected based on the given rank values at the four positions, from multiple shafts whose bending stiffnesses have been measured in advance at the four positions and that are each given one rank value among multiple-scale rank values in accordance with measured bending stiffness values.

15. An extraction method of an impact time in a swing for extracting an impact time in a swing based on measurement values from a sensor attached to a grip of a golf club and capable of measuring angular velocities about three axes when a golf ball is hit by the golf club, the method comprising the steps of:

judging whether or not an angular velocity ω

z about a shaft axis, which is the z axis, in a predetermined time duration in measured data is over range;

configuring a first provisional impact time when a judgment of over range is obtained in the step of judging, and configuring a second provisional impact time when a judgment of over range has not been obtained;

acquiring three candidates for impact time from respective time-series waveforms of an angular velocity ω

x about an x axis, an angular velocity ω

y about a y axis, and an angular velocity ω

z about a z axis using the configured first or second provisional impact time as a reference; and

determining impact time in accordance with a predetermined determination criterion from the three candidates for impact time.

16. The extraction method of an impact time in a swing according to claim 15, wherein the first provisional impact time is set to a time at which over range has occurred in the time-series waveform of the angular velocity ω

z.

17. The extraction method of an impact time in a swing according to claim 15, wherein when a minimum value has occurred in the time-series waveform of the angular velocity ω

z after a time at which a maximum value has occurred but before a first predetermined time, the second provisional impact time is set as a time at which a maximum value has occurred after the time at which the minimum value has occurred but before a second predetermined time.

18. The extraction method of an impact time in a swing according to claim 15, wherein when a minimum value has not occurred in the time-series waveform of the angular velocity ω

z after a time at which a maximum value has occurred but before a first predetermined time, the maximum value is set as the second provisional impact time.

19. The extraction method of an impact time in a swing according to claim 16, wherein the candidate of impact time acquired from the time-series waveform of the angular velocity ω

x is set to be a time at which a minimum value has occurred before a third predetermined time but after a time at which a local maximum value has firstly occurred in a first predetermined time duration around the first provisional impact time;

the candidate of impact time acquired from the time-series waveform of the angular velocity ω

y is set to be a time at which a turning point has firstly occurred in a second predetermined time duration around the first provisional impact time; and

the candidate of impact time acquired from the time-series waveform of the angular velocity ω

z is set to be a time at which a turning point has firstly occurred after the first provisional impact time but before a fourth predetermined time.

20. The extraction method of an impact time in a swing according to claim 17, wherein the candidate of impact time acquired from the time-series waveform of the angular velocity ω

x is set to be a time at which a minimum value has occurred in a first predetermined time duration around the second provisional impact time, after a time at which a local maximum value has firstly occurred but before a third predetermined time;

the candidate of impact time acquired from the time-series waveform of the angular velocity ω

y is set to be a time at which a turning point has firstly occurred in a second predetermined time duration around the second provisional impact time; and

the candidate of impact time acquired from the time-series waveform of the angular velocity ω

z is set to be a time at which a turning point has firstly occurred in a third predetermined time duration around the second provisional impact time.