Motion analysis method and motion analysis device

Abstract

A motion analysis device includes a calculation unit which specifies a first imaginary plane, that is, a shaft plane formed by a first line segment representing a direction in which a shaft part of a sporting gear in a static posture extends and a second line segment representing a ball hitting direction, with the use of an output from an inertial sensor.

What is claimed is: 
     
         1 . A motion analysis method comprising:
 calculating, with the use of an output from a first inertial sensor installed above a sporting gear, to specify a first imaginary plane formed by a first line segment representing a direction in which a shaft part of the sporting gear in a static posture extends and a second line segment representing a ball hitting direction.   
     
     
         2 . The motion analysis method according to  claim 1 , wherein the output from the first inertial sensor includes an output from an acceleration sensor, and
 the first line segment is decided by calculating an inclination of the shaft part of the sporting gear with respect to a direction of gravity, with the use of the output from the acceleration sensor in the static posture, and then using the inclination and length information of the shaft part.   
     
     
         3 . The motion analysis method according to  claim 1 , wherein the second line segment is a direction intersecting with a ball hitting surface of the sporting gear. 
     
     
         4 . A motion analysis method comprising:
 specifying, with the use of an output from a second inertial sensor installed above a subject's arm, a position of the subject's shoulder in a static posture; and   calculating to specify a second imaginary plane formed by a first line segment connecting the position of the shoulder and a ball hitting position and a second line segment representing a ball hitting direction.   
     
     
         5 . The motion analysis method according to  claim 4 , wherein the output from the inertial sensor includes an output from an acceleration sensor, and
 an inclination of a direction in which the subject's arm extends with respect to a direction of gravity is calculated using the output from the acceleration sensor in the static posture, and the position of the shoulder is decided using the inclination and length information of the subject's arm.   
     
     
         6 . The motion analysis method according to  claim 4 , wherein the second line segment is a direction intersecting with a ball hitting surface of the sporting gear. 
     
     
         7 . A motion analysis method comprising:
 calculating, with the use of an output from a first inertial sensor mounted above a sporting gear, to specify a first imaginary plane formed by a first line segment representing a direction in which a shaft part of the sporting gear in a static posture extends and a second line segment representing a ball hitting direction; and   specifying, with the use of an output from a second inertial sensor installed above a subject's arm, a position of the subject's shoulder in the static posture, and calculating to specify a second imaginary plane formed by a third line segment connecting the position of the shoulder and a ball hitting position and the second line segment representing the ball hitting direction.   
     
     
         8 . The motion analysis method according to  claim 1 , wherein the first imaginary plane is rotated about the second line segment as a rotation axis, to specify a second imaginary plane. 
     
     
         9 . The motion analysis method according to  claim 7 , wherein the first imaginary plane and the second imaginary plane are displayed. 
     
     
         10 . The motion analysis method according to  claim 9 , wherein a trajectory of a swing is displayed, superimposed on the first imaginary plane and the second imaginary plane. 
     
     
         11 . A motion analysis device comprising:
 a first calculation unit which specifies, with the use of an output from a first inertial sensor mounted above a sporting gear, a first imaginary plane formed by a first line segment representing a direction in which a shaft part of the sporting gear in a static posture extends and a second line segment representing a ball hitting direction; and   a second calculation unit which specifies, with the use of an output from a second inertial sensor installed above a subject's arm, a position of the subject's shoulder in the static posture, and specifies a second imaginary plane formed by a third line segment connecting the position of the shoulder and a ball hitting position and the second line segment representing the ball hitting direction.