US2015251054A1PendingUtilityA1

Point of contact detection

39
Assignee: HEAD TECHNOLOGY GMBHPriority: Mar 7, 2014Filed: Mar 6, 2015Published: Sep 10, 2015
Est. expiryMar 7, 2034(~7.6 yrs left)· nominal 20-yr term from priority
Inventors:Reinhard SchneiderStefan Mohr
A63B 2220/40A63B 49/00A63B 2220/833G01B 7/004A63B 2024/0043A63B 24/0021A63B 2059/0003A63B 60/002
39
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Claims

Abstract

The present invention is directed to a process for determining at least one first coordinate of the point of contact of a ball on the strings of a ball game racquet, as well as a ball game racquet suitable for carrying out such a process.

Claims

exact text as granted — not AI-modified
1 . Process for determining at least one first coordinate of the point of contact of a ball on the strings of a ball game racquet with a racquet head and a handle section, wherein the longitudinal axis of the ball game racquet defines an x-coordinate, the transverse axis of the ball game racquet defines a y-coordinate and the line perpendicular to the strings defines a z-coordinate, comprising the following steps:
 a) measuring at least one kinematic basic parameter in a first direction as a function of time at a first point of the ball game racquet, preferably with a measurement rate of at least 200 Hz;   b) transforming the measured kinematic basic parameter into the frequency domain; and   c) calculating the first coordinate of the point of contact on the basis of the transformed kinematic basic parameter in the frequency domain.   
     
     
         2 . Process for determining a first and a second coordinate of the point of contact of a ball on the strings of a ball game racquet with a racquet head and a handle section, wherein the longitudinal axis of the ball game racquet defines an x-coordinate, the transverse axis of the ball game racquet defines a y-coordinate and the line perpendicular to the strings defines a z-coordinate, comprising the following steps:
 a) measuring a first kinematic basic parameter in a first direction as a function of time at a first point of the ball game racquet, preferably with a measurement rate of at least 200 Hz;   b) measuring a second kinematic basic parameter in a second direction as a function of time at a second point of the ball game racquet, preferably with a measurement rate of at least 200 Hz;   c) transforming the measured first kinematic basic parameter and the measured second kinematic basic parameter and/or a linear combination of the measured first and second basic parameter into the frequency domain; and   d) calculating the first and second coordinates of the point of contact on the basis of the transformed kinematic basic parameter(s) in the frequency domain.   
     
     
         3 . Process according to  claim 2 , wherein the first direction is essentially identical to the second direction. 
     
     
         4 . Process according to  claim 2 , wherein the first point is different from the second point. 
     
     
         5 . Process according to  claim 1 , wherein the determination of the first and/or second coordinate of the point of contact on the basis of the transformed kinematic basic parameter(s) in the frequency domain comprises:
 a) determining a characteristic frequency interval;   b) determining at least one characteristic value of the first and/or second kinematic basic parameter with respect to the characteristic frequency interval; and   c) calculating the first and/or second coordinate of the point of contact on the basis of the at least one characteristic value.   
     
     
         6 . Process according to  claim 5 , wherein the lower limit of the characteristic frequency interval is between 0 Hz and 100 Hz, preferably between 10 Hz and 80 Hz and especially preferred between 25 Hz and 75 Hz. 
     
     
         7 . Process according to  claim 5 , wherein the upper limit of the characteristic frequency interval is between 50 Hz and 500 Hz, preferably between 75 Hz and 400 Hz and especially preferred between 100 Hz and 300 Hz. 
     
     
         8 . Process according to  claim 5 , wherein the characteristic value comprises one or a combination of the following values: local or absolute minimum of the first and/or second kinematic basic parameter in the characteristic frequency interval, local or absolute maximum of the first and/or second kinematic basic parameter in the characteristic frequency interval, mean value of the first and/or second kinematic basic parameter in the characteristic frequency interval, mean value of the first and/or second kinematic basic parameter in a subinterval of the characteristic frequency interval. 
     
     
         9 . Process according  claim 5 , wherein the first and/or second coordinate is a function of the characteristic value. 
     
     
         10 . Process according to  claim 1 , wherein the first coordinate is the x-coordinate, the first direction is essentially parallel to the z-coordinate and the first point is provided at the handle section. 
     
     
         11 . Process according to  claim 1 , wherein the first coordinate is the y-coordinate, the first direction is essentially parallel to the z-coordinate and the first point is provided at the racquet head. 
     
     
         12 . Process according to  claim 1 , wherein the first coordinate is the x-coordinate, the second coordinate is the y-coordinate and the first and second directions are essentially parallel to the z-coordinate. 
     
     
         13 . Process according to  claim 12 , wherein the first point is provided at the racquet head or at the handle section and the second point is provided at the racquet head. 
     
     
         14 . Process according to  claim 1 , wherein the first and/or second kinematic basic parameter is acceleration. 
     
     
         15 . Ball game racquet comprising a racquet head, a handle section, at least one first sensor for measuring at least one first kinematic basic parameter and a processing unit, wherein the first sensor and the processing unit are suitable for carrying out the process according to  claim 1 . 
     
     
         16 . Ball game racquet according to  claim 15 , furthermore comprising a second sensor for measuring at least one second kinematic basic parameter. 
     
     
         17 . Ball game racquet according to  claim 15 , wherein the first sensor is provided in or at the racquet head or handle section and wherein the second sensor is provided in or at the racquet head. 
     
     
         18 . Ball game racquet comprising a racquet head accommodating strings, a handle section, an acceleration sensor and a processing unit suitable for calculating a coordinate of the point of contact of a ball on the strings of the racquet based on the acceleration in a first direction measured by the acceleration sensor. 
     
     
         19 . Ball game racquet according to  claim 18 , wherein the acceleration sensor is provided in or at the handle section. 
     
     
         20 . Ball game racquet according to  claim 18 , wherein the first direction runs along the longitudinal axis of the racquet. 
     
     
         21 . Ball game racquet according to  claim 18 , furthermore comprising a second acceleration sensor, wherein the processing unit is suitable for calculating two coordinates of the point of contact of a ball on the strings of the racquet based on the acceleration in two directions measured by the two acceleration sensors, respectively. 
     
     
         22 . Ball game racquet according to  claim 18 , wherein the processing unit is suitable for calculating two coordinates of the point of contact of a ball on the strings of the racquet based on the acceleration in a first direction measured by the acceleration sensor. 
     
     
         23 . Ball game racquet according to  claim 18 , furthermore comprising a gyro sensor wherein the processing unit is suitable for calculating a second coordinate of the point of contact of a ball on the strings of the racquet based on the acceleration measured by the gyro sensor. 
     
     
         24 . Ball game racquet according to  claim 23 , wherein the gyro sensor is provided in or at the handle section. 
     
     
         25 . Process according to  claim 2 , wherein the determination of the first and/or second coordinate of the point of contact on the basis of the transformed kinematic basic parameter(s) in the frequency domain comprises:
 a) determining a characteristic frequency interval;   b) determining at least one characteristic value of the first and/or second kinematic basic parameter with respect to the characteristic frequency interval; and   c) calculating the first and/or second coordinate of the point of contact on the basis of the at least one characteristic value.   
     
     
         26 . Process according to  claim 2 , wherein the first coordinate is the x-coordinate, the first direction is essentially parallel to the z-coordinate and the first point is provided at the handle section. 
     
     
         27 . Process according to  claim 2 , wherein the first coordinate is the y-coordinate, the first direction is essentially parallel to the z-coordinate and the first point is provided at the racquet head. 
     
     
         28 . Process according to  claim 2 , wherein the first coordinate is the x-coordinate, the second coordinate is the y-coordinate and the first and second directions are essentially parallel to the z-coordinate. 
     
     
         29 . Process according to  claim 2 , wherein the first and/or second kinematic basic parameter is acceleration.

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