Method and System for Compensating for Wheel Wear on a Train

Abstract

A method and system for compensating for wheel wear uses position and/or speed information from an independent positioning system to measure some distance over which the train has traveled. Wheel rotation information is also collected over the distance. The wheel rotation information and distance and/or speed information are then use to determine the size of the train wheels. The method is performed periodically to correct for changes in wheel size over time due to wear so that the wheel rotation information can be used to determine train position and speed in the event of a positioning system failure.

1 . A computerized method for determining a size of a train wheel comprising the steps of; 
 inputting a speed from a positioning system installed on a train;    obtaining rotation information from a tachometer;    determining a wheel size based on the rotation information and the speed; and    outputting a signal indicating the wheel size.    
   
   
       2 . The method of  claim 1 , further comprising the steps of repeating the inputting, obtaining and determining steps a plurality of times and calculating a average of the wheel sizes determined in the determining steps.  
   
   
       3 . The method of  claim 1 , wherein the tachometer measures a rotation speed of the train wheel.  
   
   
       4 . The method of  claim 1 , wherein the tachometer measures a rotation speed of a motor connected to drive the train wheel.  
   
   
       5 . The method of  claim 1 , wherein the tachometer measures a rotation speed of a driveshaft connected to the train wheel.  
   
   
       6 . The method of  claim 1 , wherein the tachometer measures a rotation speed of a gear connected to the train wheel.  
   
   
       7 . The method of  claim 1 , wherein the wheel size based on the rotation information and the speed is used as an initial estimate, and further comprising the steps of: 
 obtaining a first position from the positioning system;    obtaining a second position from the positioning system;    calculating a distance between the first position and the second position; and    calculating an updated wheel size based at least in part of the distance and a number of wheel revolutions occurring between the first position and the second position.    
   
   
       8 . The method of  claim 1 , wherein the positioning system is a global positioning system receiver.  
   
   
       9 . The method of  claim 1 , further comprising the step of generating a second signal using the signal indicating the wheel size, the second signal having a parameter of a signal that would be generated by a wheel rotation sensor associated with a wheel of a predetermined size different from the wheel size determined in the determining step.  
   
   
       10 . The method of  claim 1 , wherein the signal indicating the wheel size is used by a train control system to determine a correct speed of the train.  
   
   
       11 . The method of  claim 1 , wherein the signal indicating the wheel size is used by a train control system to determine a correct distance traveled by the train.  
   
   
       12 . A system for determining a size of a train wheel comprising: 
 a control unit;    a positioning system connected to the control unit; and    a tachometer connected to the control unit and configured to measure a rotation speed of a component on the train;    wherein the control unit is configured to perform the steps of: 
 receiving rotation information from the tachometer;  
 obtaining a speed from the positioning system;  
 determining a wheel size based on the rotation information and the speed; and  
 outputting a signal indicating the wheel size.  
   
   
   
       13 . The system of  claim 12 , wherein the control unit is further configured to repeat the receiving, obtaining and determining steps a plurality of times and calculating an average of the wheel sizes determined in the determining steps.  
   
   
       14 . The system of  claim 12 , wherein the tachometer measures a rotation speed of the train wheel.  
   
   
       15 . The system of  claim 12 , wherein the tachometer measures a rotation speed of a motor connected to drive the train wheel.  
   
   
       16 . The system of  claim 12 , wherein the tachometer measures a rotation speed of a driveshaft connected to the train wheel.  
   
   
       17 . The system of  claim 12 , wherein the tachometer measures a rotation speed of a gear connected to the train wheel.  
   
   
       18 . The system of  claim 12 , wherein the wheel size is based on the rotation information and the speed is used as an initial estimate, and wherein the control unit is further configured to perform the steps of: 
 obtaining a first position from the positioning system;    obtaining a second position from the positioning system;    calculating a distance between the first position and the second position; and    calculating an updated wheel size based at least in part on the distance and a number of wheel revolutions occurring between the first position and the second position.    
   
   
       19 . The system of  claim 12 , wherein the positioning system is a global positioning system receiver.  
   
   
       20 . The system of  claim 12 , wherein the processor is further configured to perform the step of generating a second signal using the signal indicating the wheel size, the second signal having a parameter of a signal that would be generated by a wheel rotation sensor associated with a wheel of a predetermined size different from the wheel size determined in the determining step.  
   
   
       21 . The system of  claim 12 , wherein the signal indicating the wheel size is used by a train control system to determine a correct speed of the train.  
   
   
       22 . The system of  claim 12 , wherein the signal indicating the wheel size is used by a train control system to determine a correct distance traveled by the train.