US 11,857,855 B2
Characterization of a ball game racket frame
Harald Rosenkranz, Lauterach (AT); Nathan Elliott, Wolfurt (AT); Stefan Mohr, Dornbirn (AT); and Ralf Schwenger, Weiler-Simmerberg (DE)
Assigned to Head Technology GmbH, Kennelbach (AT)
Filed by Head Technology GmbH, Kennelbach (AT)
Filed on Jul. 16, 2021, as Appl. No. 17/377,689.
Claims priority of application No. 10 2020 004 307.0 (DE), filed on Jul. 17, 2020.
Prior Publication US 2022/0016503 A1, Jan. 20, 2022
Int. Cl. A63B 60/42 (2015.01); G06F 30/10 (2020.01)
CPC A63B 60/42 (2015.10) [G06F 30/10 (2020.01)] 20 Claims
OG exemplary drawing
 
1. A method for characterizing a racket head (1) of a ball game racket frame comprising the steps of:
(a) providing data of a ball game racket frame that describe the contour of the racket head of the ball game racket frame;
(b) automatically determining one or more of the following parameters characterizing the racket head shape on the basis of the contour data: measure of the length-width asymmetry of the racket head, measure of the deviation of the racket head shape from a circular shape, evolute of the racket head contour;
(c) outputting and/or graphically representing the determined parameter or parameters;
wherein step (a) comprises:
(i) creating an image of the racket head of the ball game racket frame with a viewing axis perpendicular to a string bed plane; and
(ii) automatically determining the contour of the racket head from the image by (1) converting the image of the racket head into a binary pixel image, wherein a threshold value is selected such that a first value is assigned to each of the pixels of the frame and a second value is assigned to each of all other pixels; and (2) identifying the frame pixels and determining the racket head contour;
wherein in step (b) a measure of the length-width asymmetry of the racket head is determined by:
(i) identifying the longitudinal diagonal (2) through the racket head contour having the greatest length;
(ii) identifying the transverse diagonal (3) through the racket head contour having the greatest width;
(iii) determining the point of intersection (4) of the longitudinal diagonal (2) with the transverse diagonal (3); and
(iv) determining the offset between the established point of intersection (4) and the midpoint (5) of the longitudinal diagonal (2).