LOAD CELL RESIDUAL FATIGUE LIFE ESTIMATION SYSTEM AND METHOD

• US 20140163909A1
• Filed: 12/11/2012
• Published: 06/12/2014
• Est. Priority Date: 12/11/2012
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Eswaran, Sivaprakash, Kempainen, Alan John, Srinivasan, Sivasubramanian, Ramamurthy, Gautham, Beligere, Sudheer
• Granted Patent: US 9,638,756 B2
• Time in Patent Office: Days
• US Class Current: 702/63
• CPC Class Codes: G01D 1/14 giving a distribution function of a value, i.e. number of times the value comes within specified ranges of amplitude
• CPC Class Codes: G01D 3/08 with provision for safeguarding the apparatus, e.g. against abnormal operation, against breakdown
• CPC Class Codes: G01G 23/01 Testing or calibrating of weighing apparatus
• CPC Class Codes: G01L 25/00 Testing or calibrating of apparatus for measuring force, torque, work, mechanical power, or mechanical efficiency
• CPC Class Codes: G01R 31/36 Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]

Abstract

A system and method for estimating the residual fatigue life of a load cell includes storing, in a memory, fatigue life reference data associated with a test load cell. A predetermined number of data storage bins are provided. Each data storage bin is representative of a predefined value range of peak loads. Peak loads applied to an in-service load cell are detected, and each is stored in an appropriate one of the data storage bins. A number of load cycles of the in-service load cell are calculated based on the detected peak loads stored in each of the data storage bins. An estimate of the residual life of the in-service load cell is calculated from the fatigue life reference data and the calculated number of load cycles of the in-service load cell.

Claims

1. A method for estimating the residual fatigue life of a load cell, comprising the steps of:

storing, in a memory, fatigue life reference data associated with a test load cell;

providing a predetermined number of data storage bins, each data storage bin representative of a predefined value range of peak loads;

detecting peak loads applied to an in-service load cell;

storing each of the detected peak loads in an appropriate one of the data storage bins;

calculating a number of load cycles of the in-service load cell based on the detected peak loads stored in each of the data storage bins; and

calculating an estimate of the residual life of the in-service load cell from the fatigue life reference data and the calculated number of load cycles of the in-service load cell.

2. The method of claim 1, wherein:

the in-service load cell has a load limit range;

the peak loads applied to the in-service load cell are sampled with a resolution of a predetermined number of bits; and

the predefined value range of each data storage bin is the load limit range divided by 2 raised to a power of the predetermined number of bits.

3. The method of claim 2, wherein:

the predetermined number of bits is equal to N; and

the predetermined number of data storage bins is equal to 2^N.

4. The method of claim 1, further comprising:

measuring a predetermined number of health parameters of the test load cell;

having the test load cell undergo a plurality of load cycles at a plurality of different load magnitudes;

periodically measuring each of the predetermined number of health parameters of the test load cell while the test load cell is undergoing the plurality of load cycles to thereby generate periodic measurement data; and

generating, based on the periodic measurement data, the fatigue life reference data.

5. The method of claim 4, further comprising:

extrapolating the periodic measurement data to determine a time-to-failure for each of the different load magnitudes;

generating a Weibull plot for each determined time-to-failure; and

generating the fatigue life reference data from the generated Weibull plots.

6. The method of claim 1, further comprising:

sampling the in-service load cell output a predetermined number of times;

determining a number of positive load peaks and a number of negative load peaks there are in the predetermined number of samples;

calculating an average amplitude magnitude of the positive load peaks;

calculating an average amplitude magnitude of the negative load peaks;

comparing the calculated average amplitude magnitudes to determine which is a greater magnitude average load peak; and

selectively storing the determined number of positive load peaks or the determined number of negative load peaks in the data storage bin associated with the greater magnitude average load peak.

7. The method of claim 6, further comprising:

comparing the determined number of positive load peaks and the determined number of negative load peaks to determine which, if either, is greater.

8. The method of claim 7, wherein:

the determined number of positive load peaks is stored in the data storage bin associated with the greater magnitude average load peak when the determined number of positive load peaks is greater than the determined number of negative load peaks;

the determined number of negative load peaks is stored in the data storage bin associated with the greater magnitude average load peak when the determined number of negative load peaks is greater than the determined number of positive load peaks.

9. The method of claim 1, further comprising:

determining if the estimate of the residual life of the in-service load cell is greater than a predetermined threshold.

10. The method of claim 9, further comprising:

activating an annunciator when the estimate of the residual life of the in-service load cell is greater than the predetermined threshold.

11. A load cell residual fatigue life estimation system, comprising:

an in-service load cell adapted to have loads applied thereto and configured, in response to the applied loads, to supply load cell output signals representative thereof;

first memory having stored therein fatigue life reference data associated with a test load cell;

second memory having stored therein a predetermined number of data storage bins, each data storage bin representative of a predefined value range of peak loads applied to the in-service load cell; and

a first processor coupled to receive the load cell output signals and configured, upon receipt thereof, to (i) detect peak loads applied to an in-service load cell and (ii) store each of the detected peak loads in an appropriate one of the data storage bins; and

a second processor in operable communication with the first memory and the second memory and configured to (i) calculate a number of load cycles of the in-service load cell based on the detected peak loads stored in each of the data storage bins and (ii) calculate an estimate of the residual life of the in-service load cell from the fatigue life reference data and the calculated number of load cycles of the in-service load cell.

12. The system of claim 11, wherein:

the in-service load cell has a load limit range;

the first processor is configured to sample the loads applied to the in-service load cell with a resolution of a predetermined number of bits; and

the predefined value range of each data storage bin is the load limit range divided by 2 raised to a power of the predetermined number of bits.

13. The system of claim 12, wherein:

the predetermined number of bits is equal to N; and

the predetermined number of data storage bins is equal to 2^N.

14. The system of claim 11, wherein the first processor is further configured to:

sample the in-service load cell output a predetermined number of times;

determine a number of positive load peaks and a number of negative load peaks there are in the predetermined number of samples;

calculate an average amplitude magnitude of the positive load peaks;

calculate an average amplitude magnitude of the negative load peaks;

compare the calculated average amplitude magnitudes to determine which is a greater magnitude average load peak; and

selectively store the determined number of positive load peaks or the determined number of negative load peaks in the data storage bin associated with the greater magnitude average load peak.

15. The system of claim 14, wherein the first processor is further configured to:

compare the determined number of positive load peaks and the determined number of negative load peaks to determine which, if either, is greater;

store the determined number of positive load peaks in the data storage bin associated with the greater magnitude average load peak when the determined number of positive load peaks is greater than the determined number of negative load peaks; and

store the determined number of negative load peaks in the data storage bin associated with the greater magnitude average load peak when the determined number of negative load peaks is greater than the determined number of positive load peaks.

16. The system of claim 11, wherein the second processor is further configured to:

determine if the estimate of the residual life of the in-service load cell is greater than a predetermined threshold.

17. The system of claim 16, further comprising:

an annunciator coupled to receive an activation signal and configured, upon receipt thereof, to generate an annunciation signal,

wherein the second processor is further configured to supply the activation signal when the estimate of the residual life of the in-service load cell is greater than the predetermined threshold.

18. The system of claim 11, wherein the second processor is further configured to generate usage pattern information.

19. A load cell, comprising:

sensor adapted to have loads applied thereto and configured, in response to the applied loads, to supply output signals representative of the applied load;

memory having stored therein a predetermined number of data storage bins, each data storage bin representative of a predefined value range of peak loads applied to the in-service load cell; and

a processor coupled to receive the output signals and configured, upon receipt thereof, to (i) detect peak loads applied to an in-service load cell and (ii) store each of the detected peak loads in an appropriate one of the data storage bins.

20. The load cell of claim 19, wherein the processor is further configured to:

sample the sensor output a predetermined number of times;

determine a number of positive load peaks and a number of negative load peaks there are in the predetermined number of samples;

calculate an average amplitude magnitude of the positive load peaks;

calculate an average amplitude magnitude of the negative load peaks;

compare the calculated average amplitude magnitudes to determine which is a greater magnitude average load peak; and

selectively store the determined number of positive load peaks or the determined number of negative load peaks in the data storage bin associated with the greater magnitude average load peak.