Analysis Device and Analysis System

Abstract

An analysis device for analyzing a spin axis of a ball receives an input of acceleration data and geomagnetic data detected on a time-series basis by a sensor device built in the ball; calculates attitude information of the ball, based on the acceleration data and the geomagnetic data; calculates the spin rate of the ball released from a subject, based on the geomagnetic data; and calculates an angle of the spin axis of the ball relative to a predetermined direction, using a predetermined filter and based on the attitude information, the spin rate, the geomagnetic data, and a first-order differential value and a second-order differential value of the geomagnetic data.

What is claimed is: 
     
         1 . An analysis device for analyzing a spin axis of a ball, the analysis device comprising:
 an information input unit configured to receive an input of acceleration data and geomagnetic data detected on a time-series basis by a sensor device built in the ball;   an attitude calculation unit configured to calculate attitude information of the ball, based on the acceleration data and the geomagnetic data;   a spin rate calculation unit configured to calculate the spin rate of the ball released from a subject, based on the geomagnetic data; and   a spin axis calculation unit configured to calculate an angle of the spin axis of the ball relative to a predetermined direction, using a predetermined filter and based on the attitude information, the spin rate, the geomagnetic data, and a first-order differential value and a second-order differential value of the geomagnetic data.   
     
     
         2 . The analysis device according to  claim 1 , wherein the spin axis calculation unit is configured to calculate the angle of the spin axis of the ball in a predetermined period around a timing at which the ball was released. 
     
     
         3 . The analysis device according to  claim 1 , wherein the spin axis calculation unit is configured to, based on the attitude information, the spin rate, the geomagnetic data, the first-order differential value, and the second-order differential value, calculate the angle of the spin axis of the ball by applying the predetermined filter to an observation equation where the geomagnetic data, the first-order differential value, and the second-order differential value are observation values. 
     
     
         4 . The analysis device according to  claim 1 , further comprising a direction calculation unit configured to calculate a traveling direction of the ball released from the subject, using the predetermined filter and based on the acceleration data, wherein
 the predetermined direction is the traveling direction calculated by the direction calculation unit.   
     
     
         5 . The analysis device according to  claim 4 , wherein the direction calculation unit is configured to calculate a rotation matrix that defines the traveling direction, by applying the predetermined filter to
 a state equation where the rotation matrix that defines the traveling direction is a state value, and   an observation equation where a maximum value of the acceleration data in a predetermined period is an observation value, the predetermined period being a period around a timing at which the ball was released.   
     
     
         6 . The analysis device according to  claim 1 , wherein
 the sensor device includes a low acceleration sensor configured to detect a low acceleration, and a high acceleration sensor configured to detect a high acceleration,   the acceleration data includes low acceleration data detected by the low acceleration sensor, and high acceleration data detected by the high acceleration sensor, and   the attitude calculation unit is configured to, when calculating initial attitude information of the ball, adopt the low acceleration data as the acceleration data.   
     
     
         7 . The analysis device according to  claim 1 , wherein the predetermined filter is an extended Kalman filter. 
     
     
         8 . An analysis device for analyzing a spin axis of a ball, the analysis device comprising:
 an information input unit configured to receive an input of acceleration data and geomagnetic data detected on a time-series basis by a sensor device built in the ball;   an attitude calculation unit configured to calculate attitude information of the ball, based on the acceleration data and the geomagnetic data;   a spin rate calculation unit configured to calculate the spin rate of the ball released from a subject, based on the geomagnetic data; and   a spin axis calculation unit configured to calculate an angle of the spin axis of the ball relative to a predetermined direction, using a predetermined filter and based on the attitude information, the spin rate, the acceleration data, and a first-order differential value and a second-order differential value of the acceleration data.   
     
     
         9 . The analysis device according to  claim 8 , wherein the spin axis calculation unit is configured to, based on the attitude information, the spin rate, the acceleration data, the first-order differential value, and the second-order differential value, calculate the angle of the spin axis of the ball by applying the predetermined filter to an observation equation where the acceleration data, the first-order differential value, and the second-order differential value are observation values. 
     
     
         10 . An analysis system comprising:
 an analysis device for analyzing a spin axis of a ball; and   a sensor device built in the ball,   the analysis device including:
 an information input unit configured to receive an input of acceleration data and geomagnetic data detected on a time-series basis by the sensor device; 
 an attitude calculation unit configured to calculate attitude information of the ball, based on the acceleration data and the geomagnetic data; 
 a spin rate calculation unit configured to calculate the spin rate of the ball released from a subject, based on the geomagnetic data; and 
 a spin axis calculation unit configured to calculate an angle of the spin axis of the ball relative to a predetermined direction, using a predetermined filter and based on the attitude information, the spin rate, the geomagnetic data, and a first-order differential value and a second-order differential value of the geomagnetic data.