Golf club shaft fitting method

• US 9,630,066 B2
• Filed: 09/24/2013
• Issued: 04/25/2017
• Est. Priority Date: 09/25/2012
• Status: Active Grant

• Current Assignee: Sumitomo Rubber Industries Limited
• Original Assignee: Dunlop Sports Co. Ltd. (Sumitomo Rubber Industries Limited), Sumitomo Rubber Industries Limited
• Inventors: Kato, Masatoshi
• Primary Examiner(s): BLAU, STEPHEN LUTHER
• Application Number:
  US14/430,601
• Publication Number:
  US 20150224371A1
• Time in Patent Office: 1,309 Days
• CPC Class Codes: A61B 2503/10 Athletes
• CPC Class Codes: A61B 5/1122 of movement trajectories
• CPC Class Codes: A61B 5/6895 Sport equipment
• CPC Class Codes: A63B 2220/40 Acceleration
• CPC Class Codes: A63B 2220/803 Motion sensors
• CPC Class Codes: A63B 2220/833 Sensors arranged on the exercise apparatus or sports implement
• CPC Class Codes: A63B 2225/50 Wireless data transmission, e.g. by radio transmitters or telemetry
• CPC Class Codes: A63B 53/00 Golf clubs
• CPC Class Codes: A63B 53/10 Non-metallic shafts
• CPC Class Codes: A63B 53/14 Handles
• 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: A63B 60/46 Measurement devices associated with golf clubs, bats, rackets or the like for measuring physical parameters relating to sporting activity, e.g. baseball bats with impact indicators or bracelets for measuring the golf swing
• CPC Class Codes: A63B 69/3632 Clubs or attachments on clubs, e.g. for measuring, aligning A63B69/3614 takes precedence; clubs for swinging exercises in general A63B15/00

Abstract

A fitting method, of a shaft of a golf club, for selecting a shaft having a torque 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 the golf club and capable of measuring angular velocities about three axes when a golf ball is hit by the golf club; obtaining a predetermined index value for the angular velocities quantified from the measurement values; and selecting a shaft matching the golfer from among multiple shafts whose torques have been measured in advance, based on a relationship established through test-hitting performed in advance between the index value and a torque of a shaft.

Claims

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

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

obtaining a predetermined index value for the angular velocities quantified from the measurement values; and

selecting a shaft matching the golfer from among multiple shafts whose torques have been measured in advance, based on a relationship established through test-hitting performed in advance between the index value and a torque of a shaft,

wherein, when x-axis is oriented in a direction along toe-heel direction of a golf club head, when y-axis is oriented in a direction in which a ball is hit, and when z-axis is oriented to match an axial direction of a shaft, the fitting method further includes the steps of;

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

calculating t_<sub>ω

y</sub>_<sub>max˜

imp</sub>, which is a time from when a grip angular velocity about the y-axis becomes maximum during a downswing to when the impact occurs;

calculating ω

x_<sub>ω

y</sub>__max˜

, which is an average value of a grip angular velocity about the x-axis from when the grip angular velocity about the y-axis becomes maximum to when the impact occurs;

calculating, as the index value, a magnitude of a change amount of the grip angular velocity about the x-axis per unit of time by dividing the calculated ω

x_<sub>ω

y</sub>_<sub>max˜

imp</sub> by t_<sub>ω

y</sub>_<sub>max˜

imp</sub>; and

calculating the torque of the shaft from the calculated magnitude of the change amount of the grip angular velocity about the x-axis per unit of time, using an approximate formula that is prepared in advance through test-hitting and that expresses a relationship between a torque of the shaft and the magnitude of the change amount of the grip angular velocity about the x-axis.

2. The fitting method of claim 1, wherein the sensor is attached to a grip end.

3. The fitting method of claim 1, wherein, as the approximate formula used for calculating the torque, one formula among multiple approximate formulae prepared in accordance with a magnitude of ω

z<sub>—

top</sub> which is a change amount of a grip angular velocity about the z-axis around the top is used.

4. The fitting method of claim 3, wherein, among the multiple approximate formulae, a first approximate formula is used when ω

z<sub>—

top</sub> is not lower than 20 (deg/s), and a second approximate formula is used when ω

z_{13 top} is lower than 20 (deg/s).

5. The fitting method of claim 1, wherein the fitting method further includes the steps of:

calculating, as the index value, ω

z<sub>—

top</sub>, which is a change amount of a grip angular velocity about the z-axis around the top; and

calculating the torque of the shaft from the calculated change amount of the grip angular velocity about the z-axis, using an approximate formula that is prepared in advance through test-hitting and that expresses a relationship between a torque of the shaft and the change amount of the grip angular velocity about the z-axis.

6. The fitting method of claim 5, wherein, as the approximate formula used for calculating the torque, one formula among multiple approximate formulae prepared in accordance with a magnitude of the change amount of the grip angular velocity about the z-axis from when the top is reached to when a grip angular velocity about the y-axis becomes maximum during a downswing is used;

and

wherein a magnitude of the change amount of the grip angular velocity about the z-axis is a value obtained by dividing ω

z_<sub>top˜

ω

y</sub>__max, which is an average value of the grip angular velocity about the z-axis from when the top is reached to when the grip angular velocity about the y-axis becomes maximum during the downswing, by t_<sub>top˜

ω

y</sub>__max, which is a time from when the top is reached to when the grip angular velocity about the y-axis becomes maximum during the downswing.

7. The fitting method of claim 6, wherein, among the multiple approximate formulae, a third approximate formula is used when ω

z_<sub>top˜

ω

y</sub>__max / t_<sub>top˜

ω

y</sub>__max, which is a value obtained from the dividing, is not higher than −

500 (deg/s²), and a fourth approximate formula is used when ω

z_<sub>top˜

ω

y</sub>__max/t_<sub>top˜

ω

y</sub>__max is higher than −

500 (deg/s²).