Methods and systems employing strain gauge signals to determine the dynamics of moving railcars

• US 5,883,337 A
• Filed: 03/24/1997
• Issued: 03/16/1999
• Est. Priority Date: 03/24/1997
• Status: Expired due to Term

• Current Assignee: Consolidated Rail Corporation (Norfolk Southern Corp.)
• Original Assignee: Consolidated Rail Corporation (Norfolk Southern Corp.)
• Inventors: Dolan, Joseph F., Davis, Lawrence J. III, Niemiec, Daniel G.
• Primary Examiner(s): BIEGEL, RONALD L
• Application Number:
  US08/823,814
• Time in Patent Office: 722 Days
• Field of Search: 177/163, 177/132, 177/50, 73/1.13, 73/1.15, 702/42
• US Class Current: 177/163
• CPC Class Codes: G01G 19/047 using electrical weight-sensitive devices
• CPC Class Codes: G01P 3/66 using electric or magnetic means G01P3/80 takes precedence; measuring short time intervals G04F8/00, G04F10/00

Abstract

The present invention provides a system and method for measuring weight and speed of a moving railcar through dynamic processing of a voltage signal from at least one strain gauge embedded into a rail on the railroad track. The system comprises at least one strain gauge, an amplifier circuit, a converter circuit, and a first processing means. The method performed by the first processing means is a state machine expert system algorithm which dynamically determines the baseline non-stressed voltage level and the peak voltage level upon the strain gauge being stressed by a moving railcar passing over the strain gauge. The method further provides for eliminating the effects of debounce on the weight calculations by continuously monitoring the voltage signal from the strain gauge for a predetermined period of time after an initial peak is detected and updating that value if a greater peak is detected within the predetermined period of time. Other aspects of the present invention include a second processing means which performs fault tolerance and weight calculations based on the baseline voltage level and peak voltage level of each operating strain gauge. The system also provides for transmitting control signals to external braking devices located on the railroad track for improved control in coupling of the moving railcars.

Claims

1. A measuring system for determining properties associated with a moving railcar, the system comprising:

at least one strain gage adapted for coupling to at least one of two parallel rails of a railroad track;

an amplifier circuit for receiving and amplifying signals from the at least one strain gage, resulting in amplified signals; and

a first processing means for processing the amplified signals and for

(i) monitoring the amplified signals for a rate of voltage increase that is greater than a predetermined value that is indicative of the moving railcar passing directly over the at least one strain gage;

(ii) determining a baseline voltage level from the amplified signals until the rate of voltage increase of the amplified signals exceeds the predetermined value;

the baseline voltage level being equal to the minimum voltage of the amplified signals prior to the rate of voltage increase of the amplified signals exceeding the predetermined value;

(iii) determining a peak voltage level of the amplified signals after the rate of voltage increase of the amplified signals exceeds the predetermined valve.

2. The system of claim 1 wherein there are four strain gauges adapted for coupling to at least one of two parallel rails of a railroad track.

3. The system of claim 2 wherein, when coupled, two of the four strain gauges are coupled to one of the parallel rails and the other two of the four strain gauges are coupled to the other of the parallel rails.

4. The system of claim 3 wherein the strain gauges, when coupled to the parallel rails, are positioned such that both wheels on a first axle of the moving railcar pass over strain gauges approximately simultaneously.

5. The system of claim 4 further comprising a converter circuit for receiving the amplified signal and for converting the amplified signal to a digital signal for processing by the first processing means.

6. The system of claim 5, further comprising:

a noise reduction circuit associated with the amplifier circuit for reducing noise associated with each of the four strain gages; and

a surge protection circuit for protecting the converter circuit and the first processing means from voltage surges.

7. The system of claim 1, further comprising:

a second processing means for receiving the baseline voltage level and a differential voltage equal to the difference between the peak voltage level and the baseline voltage level from the first processing means and for determining a weight reading by multiplying the differential voltage by a constant that equates voltage to weight.

8. The system of claim 7, further comprising a display means for displaying the weight reading determined by the second processing means.

9. The system of claim 7, further comprising a communication means for transmitting the weight reading of the moving railcar from the second processing means to an external terminal.

10. The system of claim 5, wherein the two strain gauges coupled to one of the parallel rails are a known distance apart and wherein the two strain gauges coupled to the other of the parallel rails are a known distance apart and wherein the system further comprises:

a second processing means for

(i) receiving the baseline voltage level and a differential voltage equal to the difference between the peak voltage level and the baseline voltage level from the first processing means for each strain gauge;

(ii) determining a weight reading for each strain gauge by multiplying the differential voltage for the respective strain gauge by a constant that equates voltage to weight; and

(iii) determining a time difference between receiving the peak voltage level from one of the strain gauges coupled to the one rail and the other of the strain gauges coupled to the same rail the time difference being indicative of a time required for an axle of the moving railcar to travel the known distance.

11. The system of claim 10 wherein the second processing means calculates a speed of the moving railcar by using the time difference and the known distance.

12. The system of claim 11 further comprising a controller means for transmitting signals representative of the speed and the weight of the moving railcar to retarder control mechanisms located on the track such that the speed and weight may be used to determine if braking or other railcar control must be initiated.

13. The system of claim 10, wherein the second processing means is for determining an average weight from the weight indicated by the peak voltage level of each of the strain gauges.

14. The system of claim 1, wherein the first processor is for determining debounce effects by determining if the rate of voltage increase of the amplified signals after the determination of the peak voltage level is greater than the predetermined value.

15. A method of determining dynamic properties of a moving railcar, the method comprising the steps of:

coupling at least one strain gauge to a section of railroad track;

amplifying a signal from the at least one strain gauge to produce an amplified signal;

monitoring the amplified signal for a rate of voltage increase that is greater than a predetermined value that is indicative of the moving railcar passing directly over the at least one strain gage;

determining a baseline voltage level from the amplified signal until the rate of voltage increase of the amplified signals exceeds the predetermined value;

the baseline voltage level being equal to the minimum voltage of the amplified signal prior to the rate of voltage increase of the amplified signals exceeding a predetermined value; and

determining a peak voltage level of the amplified signal after the rate of voltage increase of the amplified signals exceeds the predetermined valve.

16. The method of claim 15, further comprising the step of:

calculating a weight of the moving railcar according to each of the at least one strain gauges by determining a difference between the peak voltage level and the baseline voltage level and multiplying the difference by a predefined conversion factor.

17. The method of claim 15, and the method farther comprising the steps of:

wherein the at least one strain gauge comprises at least four strain gauges

coupling the at least four strain gauges in a section of railroad track comprising two parallel rails wherein two of the four strain gauges are coupled to one of the parallel rails a known distance apart and the other two of the four strain gauges are coupled to the other of the parallel rails the known distance apart;

recording a first time when the peak voltage level was transmitted by one of the four strain gauges;

recording a second time when the peak voltage level was transmitted by the other of the four strain gauges embedded in the same parallel rail as the one of the four strain gauges;

calculating a speed of the moving railcar by determining a difference between the first time and the second time and dividing the known distance by the difference.

18. A measuring system for determining properties associated with a moving railcar, the system comprising:

at least one strain gage adapted for coupling to at least one of two parallel rails of a railroad track;

an amplifier circuit for receiving and amplifying signals from the at least one strain gauge, resulting in amplified signals;

a first processing means for processing the amplified signals and for

(i) monitoring the amplified signals for a rate of voltage increase that is greater than a predetermined value that is indicative of the moving railcar passing directly over the at least one strain gage;

(ii) determining a baseline voltage level from the amplified signals until the rate of voltage increase of the amplified signals exceeds the predetermined value;

the baseline voltage level being equal to the minimum voltage of the amplified signals prior to the rate of voltage increase of the amplified signals exceeding a predetermined value;

(iii) determining a peak voltage level after the rate of voltage increase of the amplified signals exceeds the predetermined valve; and

a second processing means for receiving the baseline voltage level and a differential voltage equal to the difference between the peak voltage level and the baseline voltage level from the first processing means and for determining a weight reading by multiplying the differential voltage by a constant that equates voltage to weight.

19. The system of claim 18, wherein the first processor is for determining debounce effects by determining if the rate of voltage increase of the amplified signals after the determination of the peak voltage level is greater than the predetermined value.

20. A measuring system for determining properties associated with a moving railcar, the system comprising:

at least two strain gauges adapted for coupling to at least one of two parallel rails of a railroad track, the at least two strain gauges being coupled to the at least one of the parallel rails at a known distance apart;

an amplifier circuit for receiving and amplifying signals from the at least two strain gauges, resulting in amplified signals;

a first processing means for processing the amplified signals and for

(i) monitoring the amplified signals for each of the strain gauges for a rate of voltage increase that is greater than a predetermined value that is indicative of the moving railcar passing directly over the each of the strain gauges;

(ii) determining for each strain gauge a baseline voltage level from the amplified signals until the rate of voltage increase of the amplified signals exceeds the predetermined value;

the baseline voltage level being equal to the minimum voltage of the amplified signals prior to the rate of voltage increase of the amplified signals exceeding a predetermined value;

(iii) determining for each strain gauge a peak voltage level after the rate of voltage increase of the amplified signals exceeds the predetermined valve;

a second processing means for

(i) receiving the baseline voltage level and a differential voltage equal to the difference between the peak voltage level and the baseline voltage level for each strain gauge from the first processing means

(ii) determining a weight reading by multiplying the differential voltage by a constant that equates voltage to weight for each strain gauge; and

(iii) determining a time difference between receiving the peak voltage level from one of the strain gauges and the peak voltage level from the other of the strain gauges, the time difference being indicative of a time required for an axle of the moving railcar to travel the known distance.

21. The system of claim 20, wherein the second processor is for determining the speed of the railcar from the determined time difference.

22. A measuring system for determining properties associated with a moving railcar, the system comprising:

at least two strain gauges adapted for coupling to at least one of two parallel rails of a railroad track, the at least two strain gauges being coupled to the at least one of the parallel rails at a known distance apart;

an amplifier circuit for receiving and amplifying signals from the at least two strain gauges, resulting in amplified signals;

a first processing means for processing the amplified signals and for

(i) monitoring the amplified signals for each of the strain gauges for a rate of voltage increase that is greater than a predetermined value that is indicative of the moving railcar passing directly over the each of the strain gauges;

(ii) determining for each strain gauge a baseline voltage level from the amplified signals until the rate of voltage increase of the amplified signals exceeds the predetermined value;

the baseline voltage level being equal to the minimum voltage of the amplified signals prior to the rate of voltage increase of the amplified signals exceeding a predetermined value;

(iii) determining for each strain gauge a peak voltage level after the rate of voltage increase of the amplified signals exceeds the predetermined value;

a second processing means for

(i) receiving the baseline voltage level and a differential voltage equal to the difference between the peak voltage level and the baseline voltage level for each strain gauge from the first processing means

(ii) determining a weight reading by multiplying the differential voltage by a constant that equates voltage to weight for each strain gauge;

(iii) determining a time difference between receiving the peak voltage level from one of the strain gauges and the peak voltage level from the other of the strain gauges, the time difference being indicative of a time required for an axle of the moving railcar to travel the known distance;

(iv) determining a speed of the railcar from the determined time difference.