SWING QUALITY MEASUREMENT SYSTEM

• US 20190209909A1
• Filed: 03/15/2019
• Published: 07/11/2019
• Est. Priority Date: 07/16/2015
• Status: Active Grant

• Current Assignee: Newlight Capital, LLC
• Original Assignee: Blast Motion Incorporated
• Inventors: THORNBRUE, James, CHERVENY, Patrick, BOSE, Bhaskar, BENTLEY, Michael, KAPS, Ryan
• Granted Patent: US 10,456,653 B2
• Time in Patent Office: Days
• CPC Class Codes: A63B 2069/0008 for batting
• CPC Class Codes: A63B 2220/18 Inclination, slope or curvature
• CPC Class Codes: A63B 2220/833 Sensors arranged on the exercise apparatus or sports implement
• CPC Class Codes: A63B 69/3635 with sound-emitting source
• CPC Class Codes: A63B 69/3685 Putters or attachments on putters, e.g. for measuring, aligning A63B69/3614 takes precedence
• CPC Class Codes: G01P 15/0888 for indicating angular acceleration
• CPC Class Codes: G06F 2218/08 Feature extraction
• CPC Class Codes: G06F 2218/12 Classification; Matching
• CPC Class Codes: G06Q 10/0639 Performance analysis of employees; Performance analysis of enterprise or organisation operations
• CPC Class Codes: G06T 2207/30221 Sports video; Sports image
• CPC Class Codes: G06T 7/20 Analysis of motion motion estimation for coding, decoding, compressing or decompressing digital video signals H04N19/43, H04N19/51
• CPC Class Codes: G06V 40/23 Recognition of whole body movements, e.g. for sport training
• CPC Class Codes: G16H 20/30 relating to physical therapies or activities, e.g. physiotherapy, acupressure or exercising

Abstract

A system that measures a swing of a bat with one or more sensors and analyzes sensor data to create swing quality metrics. Metrics may include for example rotational acceleration, on-plane efficiency, and body-bat connection. Rotational acceleration measures the centripetal acceleration of the bat along the bat'"'"'s longitudinal axis at a point early in the rotational part of the swing; it is an indicator of the swing'"'"'s power. On-plane efficiency measures how much of the bat'"'"'s angular velocity occurs around the swing plane, the plane spanned by the bat and the bat'"'"'s sweet spot velocity at impact. Body-bat connection measures the angle between the bat and the body tilt axis, which is estimated from the trajectory of the hand position on the bat through the swing; an ideal bat-body connection is near 90 degrees. These three swing quality metrics provide a simple and useful characterization of the swing mechanics.

Claims

1. A swing quality measurement system comprising:

a memory;

a processor coupled with said memory;

a first communication interface;

a sensor configured to capture sensor data associated with a bat during a swing of said bat by a user;

a bat geometry stored in said memory, said bat geometry comprising

a hand position along a longitudinal axis of said bat; and

a sweet spot position along said longitudinal axis;

wherein said processor is coupled to said sensor via said first communication interface, and wherein

said processor is configured to

obtain said bat geometry;

receive said sensor data from said sensor;

obtain or calculate acceleration data from said sensor data;

obtain or calculate angular velocity data from said sensor data;

calculate a trajectory of said hand position from said acceleration data and said angular velocity data;

calculate a trajectory of said sweet spot position from said acceleration data and said angular velocity data;

calculate a trajectory of said longitudinal axis from said acceleration data and said angular velocity data;

determine a time of impact of said swing from said acceleration data and said angular velocity data;

calculate a body tilt axis of said user from said trajectory of said hand position, wherein said body tilt axis is perpendicular to a plane passing through three different points of said trajectory of said hand position;

calculate a swing plane, wherein said swing plane is spanned by a velocity vector of said sweet spot position at said time of impact and said longitudinal axis at said time of impact; and

,

calculate one or more swing quality metrics based on one or more of

said sensor data;

said acceleration data;

said angular velocity data;

said time of impact;

said trajectory of said hand position;

said trajectory of said sweet spot position;

said trajectory of said longitudinal axis;

said body tilt axis; and

,

said swing plane.

2. The system of claim 1, wherein said sensor comprises an inertial sensor that comprises:

a three-axis accelerometer that generates said acceleration data; and

a three-axis gyroscope that generates said angular velocity data.

3. The system of claim 1, wherein

said sensor comprises one or more cameras;

and,

said sensor data comprises images captured by said one or more cameras.

4. The system of claim 1, wherein said sweet spot position comprises one or more of

an optimum location on said bat for striking a ball;

a position on said bat that maximizes energy transfer when striking said ball;

a position on said bat that maximizes ball speed when striking said ball; and

,

a position on said bat that minimizes vibration when striking said ball.

5. The system of claim 1, wherein said processor is further configured to

calculate a start time of centripetal acceleration comprising a time during said swing at or near a time when a longitudinal acceleration changes sign, wherein said longitudinal acceleration comprises said acceleration data projected onto said longitudinal axis.

6. The system of claim 5, wherein said one or more swing quality metrics comprise a rotational acceleration metric comprising

a difference between

said longitudinal acceleration at an early rotation time, wherein said early rotation time comprises said start time of centripetal acceleration plus a fixed offset;

and

said longitudinal acceleration at said start time of centripetal acceleration.

7. The system of claim 6, wherein said fixed offset is in a range between 10 milliseconds and 50 milliseconds.

8. The system of claim 1, wherein said processor is further configured to

define a swing plane coordinate system comprising

a z-axis along said longitudinal axis;

a y-axis normal to said swing plane; and

an x-axis orthogonal to said y-axis and to said z-axis;

transform said angular velocity data to said swing plane coordinate system, to yield a time series of

transformed angular velocities, wherein each transformed angular velocity of said time series of transformed angular velocities comprises a vector sum of

a z-axis angular velocity;

a y-axis angular velocity; and

an x-axis angular velocity;

calculate a time series of rotation-on-plane ratios, each rotation-on-plane ratio of said time series of

rotation-on-plane ratios comprising a ratio of

a magnitude of said y-axis angular velocity to

a magnitude of a vector sum of said y-axis angular velocity and said x-axis angular velocity; and

,

calculate an on-plane efficiency metric of said one or more swing quality metrics based on said time series of rotation-on-plane ratios.

9. The system of claim 8, wherein

said processor is further configured to

calculate a start time of centripetal acceleration comprising a time during said swing at or near a time when a longitudinal acceleration changes sign, wherein said longitudinal acceleration comprises said acceleration data projected onto said longitudinal axis;

and,

said on-plane efficiency metric comprises

an average of said time series of rotation-on-plane ratios from said start time of centripetal acceleration to said time of impact.

10. The system of claim 1, wherein said processor is further configured to

calculate a time series of body-bat angles, wherein each body-bat angle of said time series of body-bat angles comprises

an angle between said longitudinal axis and said body tilt axis.

11. The system of claim 10, wherein said processor is further configured to

calculate a connection-at-impact metric of said one or more swing quality metrics comprising said body-bat angle at said time of impact.

12. The system of claim 11, wherein said processor is further configured to

calculate a disconnection-at-impact metric of said one or more swing quality metrics comprising an absolute value of a difference between said connection-at-impact and ninety degrees.

13. The system of claim 11, wherein said processor is further configured to

calculate a start time of centripetal acceleration comprising a time during said swing at or near a time when a longitudinal acceleration changes sign, wherein said longitudinal acceleration comprises said acceleration data projected onto said longitudinal axis;

and,

calculate a connection-early metric of said one or more swing quality metrics comprising said body-bat angle at said start time of centripetal acceleration.

14. The system of claim 13, wherein said processor is further configured to

calculate a disconnection-early metric of said one or more swing quality metrics comprising an absolute value of a difference between said connection-early metric and ninety degrees.

15. The system of claim 13, wherein said processor is further configured to

calculate a disconnection-at-impact metric of said one or more swing quality metrics comprising an absolute value of a difference between said connection-at-impact metric and ninety degrees;

calculate a disconnection-early metric of said one or more swing quality metrics comprising an absolute value of a difference between said connection-early metric and ninety degrees; and

,

calculate an average-disconnection metric of said one or more swing quality metrics comprising an average of said disconnection-at-impact metric and said disconnection-early metric.

16. The system of claim 1, further comprising

a database of swing quality metrics for a plurality of players;

and

an analytics system configured to compare a player or a potential player to said swing quality metrics for said plurality of players.

17. A swing quality measurement system comprising:

a memory;

a processor coupled with said memory;

a first communication interface;

a sensor configured to capture sensor data associated with a bat during a swing of said bat by a user;

a bat geometry stored in said memory, said bat geometry comprising

a hand position along a longitudinal axis of said bat; and

a sweet spot position along said longitudinal axis comprising one or more of

an optimum location on said bat for striking a ball;

a position on said bat that maximizes energy transfer when striking said ball;

a position on said bat that maximizes ball speed when striking said ball; and

,

a position on said bat that minimizes vibration when striking said ball;

said processor coupled to said sensor via said first communication interface, and configured to

obtain said bat geometry;

receive said sensor data from said sensor;

obtain or calculate acceleration data from said sensor data;

obtain or calculate angular velocity data from said sensor data;

calculate a trajectory of said hand position from said acceleration data and said angular velocity data;

calculate a trajectory of said sweet spot position from said acceleration data and said angular velocity data;

calculate a trajectory of said longitudinal axis from said acceleration data and said angular velocity data;

determine a time of impact of said swing from said acceleration data and said angular velocity data;

calculate a body tilt axis of said user from said trajectory of said hand position, wherein said body tilt axis is perpendicular to a plane passing through three different points of said trajectory of said hand position;

calculate a swing plane, wherein said swing plane is spanned by a velocity vector of said sweet spot position at said time of impact and said longitudinal axis at said time of impact;

calculate a start time of centripetal acceleration comprising a time during said swing at or near a time when a longitudinal acceleration changes sign, wherein said longitudinal acceleration comprises said acceleration data projected onto said longitudinal axis;

define a swing plane coordinate system comprising

a z-axis along said longitudinal axis;

a y-axis normal to said swing plane; and

an x-axis orthogonal to said y-axis and to said z-axis;

transform said angular velocity data to said swing plane coordinate system, to yield a time series of transformed angular velocities, wherein each transformed angular velocity of

said time series of transformed angular velocities comprises a vector sum of

a z-axis angular velocity;

a y-axis angular velocity; and

an x-axis angular velocity;

calculate a time series of rotation-on-plane ratios, each rotation-on-plane ratio of said time

series of rotation-on-plane ratios comprising a ratio of

a magnitude of said y-axis angular velocity to

a magnitude of a vector sum of said y-axis angular velocity and said x-axis angular velocity;

calculate a time series of body-bat angles, wherein each body-bat angle of said time series of

body-bat angles comprises

an angle between said longitudinal axis and said body tilt axis;

calculate one or more swing quality metrics comprising

a rotational acceleration metric comprising

a difference between

 

said longitudinal acceleration at an early rotation time, wherein said early rotation time comprises said start time of centripetal acceleration plus a fixed offset; and

 

said longitudinal acceleration at said start time of centripetal acceleration;

an on-plane efficiency metric comprising

an average of said time series of rotation-on-plane ratios from said start time of centripetal acceleration to said time of impact;

a connection-at-impact metric comprising

said body-bat angle at said time of impact; and

,

a connection-early metric of said one or more swing quality metrics comprising

said body-bat angle at said start time of centripetal acceleration.