Method for calibration of step length and arrangement utilizing the method

Abstract

The invention relates to a method for measuring the length of steps, a measuring arrangement utilizing the method and a sound transmitter and a sound receiver utilized in the measuring arrangement. In the method according to the invention, the distance of the person performing the measurement from a certain fixed point is measured by means of synchronized sound frequency pulses. The number of steps is measured by means of an acceleration transducer carried along by the person. The length of steps is obtained by dividing the distance advanced by the number of steps.

1 . A method for measuring the length of a person's ( 1 ) steps, in which method the distance covered (S) and the number of steps (N) used is measured, wherein in the method 
 the distance covered (S) is measured by transit time measurement of sound frequency pulses ( 12   a,    12   b,    12   c ), which are transmitted using a delay (T) between the pulses; 
 the transit time of each sound pulse is measured between the moving person ( 1 , B) and a fixed point (A); and where  
 before measuring the distance covered  
 a measuring time (M) ( 300 ) used for measuring the length of steps is determined and  
 clocks of a transmission means ( 11 ) and a reception means ( 10 ) of the sound pulses are synchronized before the transmission of a first sound pulse for the overall measuring time (M), whereby the reception means ( 10 ) of the sound pulses know both the moments of reception of the sound pulses ( 12   a,    12   b,    12   c ) and the moment of transmission ( 300 ) of each sound pulse ( 12   a,    12   b,    12   c ) and that  
   number of steps (N) taken during the measurement are measured by an acceleration transducer ( 48 ) carried along by the person.    
     
     
         2 . The method according to  claim 1 , wherein the means used for transmitting the sound pulses ( 12   a,    12   b,    12   c ) is a sound receiver ( 10 ), which can receive and indicate a sound pulse transmitted in the frequency range used.  
     
     
         3 . The method according to  claim 2 , wherein the moving person ( 1 ) has the sound transmitter ( 11 ), which transmits ( 311 - 314 ) sound frequency pulses ( 12   a,    12   b,    12   c ), which are received ( 320 - 322 ) by the sound receiver ( 10 ) at a fixed point (A).  
     
     
         4 . The method according to  claim 3 , wherein the distance estimate (S) obtained by the transit time measurement of the sound pulse ( 12   a,    12   b,    12   c ) is corrected ( 321 ) by at least one of the following factors having an effect on the transit time of the sound pulse ( 12   a,    12   b,    12   c ): the height (H) of the sound transmitter, (the angle a), the temperature of the air, the direction of the wind (angle  1 ) or the speed of the wind.  
     
     
         5 . The method according to  claim 3 , wherein after the measuring period, the sound transmitter ( 11 ) sends an ending pulse ( 330 ) of the step length measurement, which ending pulse is received ( 340 ) in the sound receiver ( 10 ) and in which the final distance (S) of the person ( 1 ) from the sound receiver ( 10 ) is calculated.  
     
     
         6 . The method according to  claim 1 , wherein the step length is calculated by dividing the measured final distance (S) by the number of steps (N) measured by the acceleration transducer ( 48 ).  
     
     
         7 . The method according to  claim 6 , wherein the number of steps (N) measured is transferred from the sound transmitter ( 11 ) to the sound receiver ( 10 ) through a wireless electric link.  
     
     
         8 . A measuring arrangement for measuring the length of a person's ( 1 ) steps, which arrangement comprises means for measuring the distance covered (S) and number of steps (N) used, wherein the measuring arrangement—the distance covered (S) is arranged to be measured by transit time measurement of sound frequency pulses ( 12   a,    12   b,    12   c ), which are transmitted using a delay (r) between the pulses; 
 the transit time of each sound pulse is arranged to be measured between a moving person ( 1 , B) and a fixed point (A) and where    before measuring the distance covered 
 a measuring time (M) ( 300 ) to be used has been determined and  
 clocks of a transmission means ( 11 ) and a reception means ( 10 ) of the sound pulses have been synchronized before the transmission of a first sound pulse for the overall measuring time (M), whereby the reception means ( 10 ) of the sound pulses have knowledge of both the moments of reception of the sound pulses ( 12   a ,  12   b ,  12   c ) and the moments of transmission ( 300 ) of each sound pulse ( 12   a ,  12   b ,  12   c ), and that  
   number of steps (N) taken during the measurement of the length of steps is arranged to be calculated from acceleration pulses caused by the steps, measured by an acceleration transducer ( 48 ) carried along by the person.    
     
     
         9 . The measuring arrangement according to  claim 8 , wherein the means for transmitting the sound pulses ( 12   a ,  12   b ,  12   c ) comprise a sound transmitter ( 11 ), which is arranged to transmit sound pulses essentially in the frequency range of 1000-2000 Hz and that the means for receiving the sound pulses comprise a sound receiver ( 10 ), which can both receive and indicate a sound pulse transmitted in the frequency range used.  
     
     
         10 . The measuring arrangement according to  claim 9 , wherein the moving person ( 1 ) has the sound transmitter ( 11 ), which is arranged to transmit ( 311 - 314 ) sound frequency pulses ( 12   a ,  12   b ,  12   c ), which are arranged to be received ( 320 - 322 ) by the sound receiver ( 10 ) at a fixed point (A).  
     
     
         11 . The measuring arrangement according to  claim 10 , wherein a distance estimate (S) obtained by the transit time measurement of the sound pulse ( 12   a ,  12   b ,  12   c ) is arranged to be corrected ( 321 ) by at least one of the following factors having an effect on the transit time of the sound pulse ( 12   a ,  12   b ,  12   c ): the height (H) of the sound transmitter, (the angle a), the temperature of the air, the direction of the wind (angle f 3 ) or the speed of the wind.  
     
     
         12 . The measuring arrangement according to  claim 10 , wherein the step length measurement is arranged to be stopped by a stopping pulse ( 330 ) sent by the sound transmitter ( 11 ).  
     
     
         13 . The measuring arrangement according to  claim 12 , wherein after the reception of the stopping pulse ( 340 ), the sound receiver ( 10 ) is arranged to calculate the final distance (S) of the person ( 1 ) from the sound receiver ( 10 ).  
     
     
         14 . The measuring arrangement according to  claim 8 , wherein the step length is arranged to be calculated by dividing the measured final distance (S) by the number of steps (N) measured by the acceleration transducer ( 48 ).  
     
     
         15 . The measuring arrangement according to  claim 14 , wherein the number of steps (N) measured is arranged to be transferred from the sound transmitter ( 11 ) to the sound-receiver ( 10 ) through a wireless electric link.  
     
     
         16 . A sound receiver ( 10 ), wherein it comprises—a central processing unit (CPU); 
 a memory; 
 a clock function ( 41 ) for calculating the transit time of a received sound pulse and for performing the calculation of the distance (S) on the basis of that;—a means for synchronizing the clock function ( 41 ) before a first received sound pulse for the overall measuring time (M);  
 a user interface ( 43 ) for inputting the initial information of the step length measurement and for presenting the measurement result of the calculated length of steps;  
 a sound frequency receiver ( 42 ) for receiving and indicating a sound signal of essentially the frequency of 1,000-2,000 Hz and  
   a power source ( 44 ).    
     
     
         17 . The sound receiver ( 10 ) according to  claim 16 , wherein the input of the initial information of the step length measurement, the determination of the transit time of the sound pulse and the determination of the length of steps on the basis of that and presenting the measurement result have been implemented by a program application saved in the sound pulse reception means ( 10 ).  
     
     
         18 . The sound receiver ( 10 ) according to  claim 17 , wherein it is part of a terminal of a cellular network.  
     
     
         19 . A sound transmitter ( 11 ), comprising 
 a central processing unit (CPU);    a memory;    a clock function ( 45 )    for transmitting a sound pulse used in the measurement at the intervals of a certain delay (r);    for detecting the end of the time (M) defined for the measurement;    for sending a measurement ending pulse;    a means for synchronizing the clock function ( 45 ) before transmitting a first sound pulse for the overall measuring time (M);    a user interface ( 47 ) for starting the step length measurement;    a sound frequency transmitter ( 46 ) for transmitting a sound signal of essentially the frequency of 1,000-2,000 Hz;    a means ( 48 ) for detecting an acceleration peak caused by a step and for saving the number (N) of the acceleration peaks detected and—a power source ( 44 ).    
     
     
         20 . The sound transmitter ( 11 ) according to  claim 19 , wherein the delay (τ) used in the transmission of the sound pulse, the length (M) of the step length measurement time and the determination of the transmission moment of the ending pulse have been implemented by a program application saved in the sound transmitter ( 10 ).  
     
     
         21 . The sound transmitter ( 11 ) according to  claim 19 , wherein it also comprises a means for transferring the number (N) of the acceleration peaks by a wireless data transfer link to another device ( 10 ).  
     
     
         22 . The sound transmitter ( 11 ) according to  claim 19 , wherein it is part of a terminal of a cellular network.