Method and system to separate optically measured coupled parameters
A system includes a first optical sensor sensitive to both a parameter of interest, Parameter1, and at least one confounding parameter, Parameter2 and a second optical sensor sensitive only to the confounding parameter. Measurement circuitry measures M 1 in response to light scattered by the first optical sensor, where M 1 =value of Parameter1+K*value of Parameter2. The measurement circuitry also measures M 2 in response to light scattered by the second optical sensor, where M 2 =value of Parameter2. Compensation circuitry determines a compensation factor, K, for the confounding parameter based on measurements of M 1 and M 2 taken over multiple load/unload cycles or over one or more thermal cycles. The compensation factor is used to determine the parameter of interest.
1. A system, comprising:
a first optical sensor disposed on or within a battery and sensitive to a parameter of interest, Parameter1, and one or more confounding parameters, the confounding parameters including at least Parameter2;
one or more second optical sensors disposed on or within the battery and sensitive to one or more confounding parameters, one of the second optical sensors sensitive to Parameter2;
measurement circuitry configured to measure M 1 in response to light scattered by the first optical sensor, where M 1 =value of Parameter1+K*value of Parameter2, and to measure M 2 in response to light scattered by the second optical sensor, where M 2 =value of Parameter 2; and
compensation circuitry configured to determine the compensation factor, K, based on statistical analysis of M 1 and M 2 taken over multiple charge/discharge cycles of the battery.
2. The system of claim 1 , wherein the compensation circuitry configured to determine the compensation factor based on a ratio of M 1 and M 2 taken over one or more thermal cycles of the battery.
3. The system of claim 1 , wherein the parameter of interest is strain and the confounding parameter is temperature or chemical concentration.
4. The system of claim 1 , further comprising battery management circuitry configured to use the compensation factor to determine the parameter of interest for the battery, the battery management circuitry further configured to determine a state of health of the battery based on the parameter of interest.
5. The system of claim 4 , wherein the battery management circuitry is configured to control one or both of the charge/discharge cycles of the battery and the environment of the battery based on the state of health of the battery.
6. The system of claim 4 , wherein:
the compensation circuitry is configured to periodically determine the compensation factor the battery over time; and
the battery management circuitry is configured to detect degradation of the battery based on a change in the compensation factor over time.
7. The system of claim 1 , wherein the optical sensors are fiber Bragg grating sensors.
8. A system, comprising:
at least a first optical sensor disposed within or on a physical or cyber physical subsystem and sensitive to a parameter of interest, Parameter 1, and sensitive to one or more confounding parameters, including Parameter2 and Parameter3;
one or more second optical sensors disposed within or on the subsystem, each second optical sensor sensitive to one or more of the confounding parameters;
measurement circuitry configured to measure light scattered by the first optical sensor and each of the second optical sensors; and
compensation circuitry configured to determine the compensation factors for each of the confounding parameters based on measurements of the light scattered by the first optical sensor and each of the second optical sensors, wherein:
the measurements are taken over multiple load/unload cycles of the subsystem and the compensation circuitry minimizes an objective function to determine the compensation factors, or
the measurements are taken over one or more cycles that span a range of values of each of the confounding parameters and the compensation circuitry determines generalized ratios of measurements obtained from the first optical sensor to measurements obtained from one or more of the second optical sensors to determine the compensation factors.
9. The system of claim 8 , wherein the optical sensors are fiber Bragg grating sensors.
10. The system of claim 8 , wherein the parameter of interest is strain, temperature, chemical composition, vibration, humidity, or acceleration and each confounding parameter is different from the parameter of interest and is strain, temperature, chemical composition, vibration, humidity, or acceleration.
11. The system of claim 8 , further comprising management circuitry configured to use the compensation factors to determine a state of health of the subsystem based on the parameter of interest and to control internal or external processes that affect the subsystem.
12. The system of claim 8 , wherein:
the compensation circuitry is configured to periodically determine at least one compensation factor of the subsystem over time; and
the management circuitry is configured to detect degradation of the subsystem based on a change in the compensation factor over time.
13. The system of claim 8 , wherein the subsystem is a load bearing support structure, the one or more confounding parameters include temperature and the compensation factor for temperature is determined based on thermal cycling.
14. The system of claim 13 , wherein the subsystem is a load bearing support structure, the one or more confounding parameters includes humidity and the compensation factor for humidity is based on humidity cycling.