Golf Club Swing Analysis Using Shaft Strain at Impact

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Solution Overview

Problem

Existing swing analysis technologies in golf do not provide accurate analysis of the swing at impact, particularly in terms of the inclination of the golf club head and the angle of the striking face, which significantly affect the play result.

Innovation Solution

A swing analysis device that includes an information input unit for acceleration, angular rate, and strain information, an attitude calculating unit, a correction unit for impact corrections using regression analysis, and a display control unit to present accurate attitude information, including lie and shaft lean angles, based on strain information.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If attitude information is calculated using only acceleration and angular rate information, then the device complexity is reduced, but the measurement precision of swing attitude at impact deteriorates

Engineering Contradiction:
Improvedevice complexityVSAvoidmeasurement precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent combines multiple sensor types (acceleration sensor, angular rate sensor, and strain sensor) to measure swing attitude. The strain sensor is integrated into the shaft to detect bending strain, which provides additional information about the swing attitude at impact that cannot be obtained from acceleration and angular rate sensors alone. This merging of multiple sensing mechanisms resolves the contradiction by maintaining device simplicity while improving measurement precision through data fusion from complementary sensors.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent uses strain information as an intermediary to correct attitude information calculated from acceleration and angular rate data. The strain sensor acts as a mediator that provides indirect measurement of the shaft's bending state, which is then used to refine the attitude calculation. This intermediary approach allows the system to achieve high measurement precision without directly measuring all physical quantities, thus avoiding excessive device complexity.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If strain sensor is added to the shaft, then the measurement precision of swing attitude at impact is improved, but the device complexity increases

Engineering Contradiction:
Improvemeasurement precisionVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The strain sensor is placed locally at a specific position on the shaft where bending strain is most significant during the swing. This localized sensing approach provides the critical impact attitude information without requiring multiple sensors throughout the entire club. The local quality principle allows the system to achieve high measurement precision by concentrating sensing capability at the most informative location, thereby minimizing overall device complexity.

Inventive Principle:
Principle #3Local quality

3Measurement precision

If detailed analysis of swing at impact is provided, then the measurement precision is improved, but the loss of time for data processing increases

Engineering Contradiction:
Improvemeasurement precisionVSAvoidloss of time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent performs preliminary calculation of attitude information throughout the swing period using acceleration and angular rate data. By continuously computing the attitude information in advance, the system prepares the data so that impact analysis can be performed quickly when the impact moment is detected. This preliminary action reduces the processing time required at impact while maintaining high measurement precision through the use of pre-computed attitude data combined with strain sensor information.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent identifies the impact moment by detecting specific characteristics in the strain sensor output and accelerates the data processing specifically at this critical moment. Rather than uniformly processing all swing data at high resolution, the system rushes through the analysis at the impact moment when precision is most critical, while using less intensive processing for other portions of the swing. This selective processing approach minimizes overall processing time while maintaining high measurement precision at the crucial impact phase.

Inventive Principle:
Principle #21Skipping (Rushing through)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables accurate analysis of the golf club swing, providing detailed impact angles and improving the accuracy of swing analysis.

Implementation Method 1

a strain gauge 221 in the toe down direction Ey

Methodology Applied
Scientific EffectStrain gauge measurement: Piezoresistive Effect

Implementation Method 2

acceleration information, angular rate information, and strain information of a shaft of the golf club, detected by a sensor attached to the shaft

Methodology Applied
Scientific EffectAcceleration sensing: Accelerometer

Implementation Method 3

angular rate information, and strain information of a shaft of the golf club, detected by a sensor attached to the shaft

Methodology Applied
Scientific EffectAngular rate sensing: Gyroscope

Data Source

PatentEP3610931B1Swing analysis device, swing analysis method, and swing analysis system
Publication Date: 2026.01.14 MIZUNO CORPORATION
  • EP3610931B1 patent drawingFigure 1
  • EP3610931B1 patent drawingFigure 2
  • EP3610931B1 patent drawingFigure 3

AI summary

A swing analysis device for analyzing a swing of a user of a golf club accepts input of acceleration information, angular rate information, and strain information of a shaft (52) of the golf club, detected by a sensor (20) attached to the shaft (52), calculates attitude information of the golf club in a swing period, based on the acceleration information and the angular rate information, corrects the attitude information of the golf club at impact, based on the strain information of the shaft (52), and displays the corrected attitude information of the golf club on a display.