Speed sensitive dragging equipment detector

1. A method of detecting an object beneath a train, the method comprising:

receiving a first signal indicative of a position of the train;

receiving a second signal indicative of a force generated by impact of the object with an impact element;

determining a speed of the train;

selecting a threshold speed value based on the speed of the train;

processing said second signal in accordance with a first procedure if the speed of the train is less than the threshold speed value; and

processing said second signal in accordance with a second procedure different from said first procedure if the speed of the train is equal to or greater than the threshold speed value, wherein the first procedure and the second procedure are selected based on a sensitivity of the impact element.

2. The method of claim 1 , wherein the threshold speed value is 20 miles per hour.

3. The method of claim 1 , wherein said first procedure includes amplifying said second signal.

4. The method of claim 1 , wherein said second procedure includes attenuating said second signal.

5. The method of claim 1 , wherein receiving said second signal includes receiving an acceleration signal.

6. The method of claim 1 , wherein selecting a threshold value includes evaluating a type of object expected to impact the impact element.

7. The method of claim 1 , wherein selecting a threshold speed value includes evaluating a mass of the object.

8. An apparatus for detecting an object beneath a train, the apparatus comprising:

an impact element configured to be disposed in a path of the object;

a sensor configured to sense an impact on the impact element;

a sensor configured to detect speed of the train; and

a processor configured to:

receive a first signal from the sensor indicative of a force generated by impact of the object with the impact element;

receive a second signal from the sensor indicative of the position of the train;

determine a threshold speed value based on the speed of the train,

implement a first procedure on said first signal when the speed of the train is less than said threshold speed value; and

implement a second procedure different from said first procedure on said first signal when the speed is equal to or greater than said threshold speed value, wherein the first procedure and the second procedure are selected based on a sensitivity of the impact element.

9. The apparatus of claim 8 , wherein the processor is configured to implement the first procedure by modulating the first signal to enable detection of forces generated by impact of the object with the impact element when the train is traveling at speeds between approximately 1 mile per hour and approximately 20 miles per hour.

10. The apparatus of claim 8 , wherein the sensor is an accelerometer.

11. The apparatus of claim 8 , wherein the processor is configured to implement the first procedure by amplifying the first signal.

12. The apparatus of claim 8 , wherein the processor is configured to implement the first procedure by increasing sensitivity of the sensor.

13. The apparatus of claim 8 , wherein:

the sensor is mounted on the impact element; and

the impact element extends in a direction approximately orthogonal to a travel direction of the train.

14. The apparatus of claim 13 , wherein:

the impact element is stationary; and

the sensor is adapted to sense accelerations in the stationary impact element caused by the impact.

15. The apparatus of claim 8 , wherein the processor is configured to determine the threshold speed value based on the position of the train and a type of the object expected to impact the impact element.

16. The apparatus of claim 15 , wherein the processor is configured to assign a threshold speed value for an object as a function of a mass of the object.

17. The apparatus of claim 15 , wherein the processor is configured to determine the threshold speed value by reference to a look-up table of threshold values for various expected types of objects and types of sensors.

18. The apparatus of claim 8 , wherein the sensor is a transducer that uses the piezoelectric effect to generate charges proportional to accelerations generated by the impact of the object with the impact element.

19. A method of detecting an object beneath a train, the method comprising:

receiving a first signal indicative of a position of the train;

receiving a second signal indicative of a force generated by impact of the object with an impact element;

determining a speed of the train;

selecting a threshold level of the speed based on the speed of the train;

comparing said speed of the train with said threshold level;

amplifying said second signal when said speed is less than the threshold level of speed and the impact element has a first sensitivity; and

attenuating said second signal when said speed is approximately equal to or greater than the threshold level of speed and the impact element has a second sensitivity greater than the first sensitivity.

20. The method of claim 15 , wherein the processor is configured to determine the type of the object expected to impact the impact element based on one or more of historical data, a mechanical structure of train equipment, and a frequency at which the train equipment is connected and disconnected.