Method of Calibrating a Data Recording Unit

Abstract

A method of calibrating a data recording unit for measuring head acceleration, including the steps of providing a data recording unit mounted to a head protector, mounting the head protector on a support, subjecting the head protector and support to a force or pressure, measuring acceleration of the head protector resulting from the force or pressure, measuring acceleration of the support resulting from the force or pressure, and determining a relationship between the measured acceleration of the head protector and of the support.

1 . A method of calibrating a data recording unit for measuring head acceleration, comprising the steps of:
 (a) providing a data recording unit mounted to a head protector;   (b) mounting the head protector on a support;   (c) subjecting the head protector and support to a force or pressure;   (d) measuring acceleration of the head protector resulting from the force or pressure;   (e) measuring acceleration of the support resulting from the force or pressure; and   (f) determining a relationship between the measured acceleration of the head protector and of the support.   
     
     
         2 . A method as claimed in  claim 1 , comprising subjecting the head protector and support or another head protector and/or support to a plurality of different forces or pressures and repeating at least steps (d) and (e) for each different force or pressure. 
     
     
         3 . A method as claimed in  claim 2 , wherein each force or pressure is applied in substantially the same direction relative to the head protector and support. 
     
     
         4 . A method as claimed in  claim 2 , further comprising subjecting the head protector and support and/or another head protector and/or support to a plurality of successive forces or pressures each applied to the head protector and support in a different direction, and repeating at least steps (d) and (e) for each different direction. 
     
     
         5 . A method as claimed in  claim 4 , wherein a plurality of forces or pressures in different directions have substantially the same strength. 
     
     
         6 . A method as claimed in  claim 1 , further comprising using the relationship to determine head acceleration from data recorded by a data recording unit mounted to a head protector. 
     
     
         7 . A method as claimed in  claim 6 , wherein the data recording unit comprises a data recording unit other than the data recording unit used to determine said relationship, for example, a data recording unit used in actual service. 
     
     
         8 . A method of determining the value of a parameter indicative of acceleration of a person's head or other object, comprising the steps of: acquiring data measured by an acceleration sensor mounted to a head protector and using a calibration method to determine from the data the value of said parameter. 
     
     
         9 . A method as claimed in  claim 8 , wherein the calibration method is derived from data describing a relationship between head acceleration and head protector acceleration. 
     
     
         10 . A method as claimed in  claim 8 , further comprising determining the direction of acceleration from the acquired data and selecting the calibration method based on the direction.