Inductive sensing system for sports performance improvement

Abstract

A measurement device may include one or more inductive structures coupled to a signal processor that measures changes in inductance. As the inductive structure moves in relation to an external conducting object, inductance changes may occur in the inductive structure. By analyzing the changes in inductance, the system may determine spatial relationships concerning the measurement device. Additionally, at least one inductive structure may be placed behind a conductive impact surface, allowing for measurement of impact characteristics without disturbing the impact surface. The measurement device may be used in or on sports equipment, such as a golf club.

What is claimed is: 
     
         1 . A system for determining spatial relationships using inductance, the system including:
 a first inductive structure;   an external conducting object;   signal processing circuitry coupled to the first inductive structure, the signal processing circuitry determining changes in inductance caused by the first inductive structure passing in the vicinity of the first inductive structure; and   a processor that determines a location of the first inductive structure based on the determined changes in inductance.   
     
     
         2 . The system of  claim 1 , wherein the system further includes a non-transitory computer-readable medium that includes a plurality of inductance change patterns to which the determined changes are compared, the comparison yielding a derived flight path of the inductive object. 
     
     
         3 . The system of  claim 1 , wherein the conducting object includes PCB and a metallization pattern. 
     
     
         4 . The system of  claim 1 , wherein the conducting object includes a three-dimensional metallization pattern. 
     
     
         5 . The system of  claim 1 , wherein the signal processing circuitry measures the duty cycle of a signal representing inductance changes, and a processor compares a plurality of measured duty cycles against a set of predetermined duty cycle patterns corresponding to a metallization pattern of the conducting object. 
     
     
         6 . The system of  claim 5 , wherein the processor normalizes the plurality of measured duty cycles for comparison against the predetermined duty cycle patterns. 
     
     
         7 . The system of  claim 1 , wherein the inductive structure is mounted at a bottom of a golf club. 
     
     
         8 . The system of  claim 7 , wherein the inductive structure is a coil on a printed circuit board. 
     
     
         9 . The system of  claim 1 , wherein the inductive structure is part of a resonant circuit that includes a capacitive structure coupled to the inductive structure, wherein the signal processing circuitry determines inductance changes by measuring shifts in a resonant frequency of the resonant circuit. 
     
     
         10 . The system of  claim 1 , further including a force-related sensor that senses a force-related attribute, wherein the inductance changes in the inductive structure are sampled at a different sampling rate by the signal processing circuitry than an output of the force-related sensor, and wherein a processor aligns digital values representing inductance changes with digital values representing the force-related attribute. 
     
     
         11 . A golf club head including:
 a shell;   a clubface coupled to the shell, the clubface having at least one conductive portion;   a first inductive element inside the shell and behind the clubface;   signal processing circuitry coupled to the first inductive structure, the signal processing circuitry determining inductance changes caused by the at least one conductive portion moving in relation to the first inductive structure upon impact with a golf ball; and   a computer-readable medium that stores data representing the inductance changes for use in analysis of the impact.   
     
     
         12 . The golf club head of  claim 11 , wherein the first inductive structure does not touch the clubface but experiences a change in inductance based on the at least one conductive portion of the clubface moving relative to the first inductive structure upon impact. 
     
     
         13 . The golf club head of  claim 11 , further including a plurality of inductive elements, the plurality including the first inductive structure and at least a second inductive structure, wherein the plurality of inductive structures are included on a monolith that is positioned substantially parallel to a back of the club face within the shell. 
     
     
         14 . The golf club head of  claim 13 , wherein the signal processing circuitry determines inductance changes for each of the plurality of inductive structures, and wherein a processor determines a location of the impact based on differences in the inductance changes between the plurality of inductive structures. 
     
     
         15 . The golf club head of  claim 11 , wherein the club head further provides the data to a processor that determines a force of the impact based on an amount of inductance change at the first inductive structure. 
     
     
         16 . The golf club head of  claim 11 , further including a transmitter that transmits the data to a processor that determines a location relative to the first inductive structure based on the determined changes in inductance. 
     
     
         17 . The golf club head of  claim 11 , wherein the first inductive structure is part of a resonant circuit that includes a capacitor coupled to the first inductive structure, and wherein the signal processing circuitry determines inductance changes by detecting shifts in a resonant frequency of the resonant circuit. 
     
     
         18 . An apparatus including:
 an inductive structure mounted on a contact structure that is positioned relative to a conductor;   signal processing circuitry coupled to the inductive structure, the signal processing circuitry determining inductance changes caused by the inductive structure moving relative to the conductor upon impact.   
     
     
         19 . The apparatus of  claim 18 , wherein determining inductance changes includes detecting a shift in a resonant frequency of a resonant structure that includes the inductive structure. 
     
     
         20 . The apparatus of  claim 18 , wherein the contact structure is a flexible monolith that is attachable to a club face, and wherein the inductive structure is one of a plurality of inductive structures on the flexible monolith.