DEVICE AND METHOD FOR MEASURING AND TRACKING THE QUANTITY OR CONCENTRATION OF A COMPOUND IN A FLUID

• US 20200132588A1
• Filed: 04/20/2018
• Published: 04/30/2020
• Est. Priority Date: 05/04/2017
• Status: Active Grant

• Current Assignee: eLichens Co.
• Original Assignee: eLichens Co.
• Inventors: LE, Thanh Trung
• Granted Patent: US 11,054,360 B2
• Time in Patent Office: Days
• CPC Class Codes: G01N 15/1404 Handling flow, e.g. hydrodynamic focusing
• CPC Class Codes: G01N 15/1429 Signal processing
• CPC Class Codes: G01N 21/3504 for analysing gases, e.g. multi-gas analysis
• CPC Class Codes: G01N 2201/124 Sensitivity

Abstract

A device for measuring and tracking over time the quantity or concentration of a component in a fluid comprises: a sensor capable of measuring a quantity or concentration of the component in the fluid and providing a quantitative signal for tracking this quantity or concentration over time; a signal-processing module comprising a low-pass filter of the quantitative tracking signal; and an output interface for providing the filtered quantitative tracking signal. The signal-processing module comprises an estimator of a value of instantaneous trend of variation of the quantitative tracking signal in a predetermined sliding time window. Also provided is means for adjusting over time a high cutoff frequency of the low-pass filter according to the estimated value of instantaneous trend of variation.

Claims

1. A device for measuring and tracking over time the quantity or concentration of a component in a fluid, comprising:

a sensor capable of measuring a quantity or concentration of the component in the fluid and providing a quantitative signal for tracking this quantity or concentration over time,

a signal-processing module comprising a low-pass filter of the quantitative tracking signal,

an output interface for providing the filtered quantitative tracking signal,

characterized in that the signal-processing module comprises;

an estimator of a value of instantaneous trend of variation of the quantitative tracking signal in a predetermined sliding time window, and

means for adjusting over time a high cutoff frequency of the low-pass filter according to the estimated value of instantaneous trend of variation.

2. The measuring and tracking device according to claim 1, wherein the estimator is designed to estimate the value of instantaneous trend of variation of the quantitative tracking signal by providing a value of slope of this signal in the predetermined sliding time window, in particular via linear regression.

3. The measuring and tracking device according to claim 1, wherein the adjustment means are designed in such a way as to:

reduce the high cutoff frequency of the low-pass filter when the absolute value of the estimated value of instantaneous trend of variation decreases, and

increase the high cutoff frequency of the low-pass filter when the absolute value of the estimated value of instantaneous trend of variation increases.

4. The measuring and tracking device according to claim 1, wherein the low-pass filter is designed to carry out, after time sampling of the quantitative tracking signal, a digital filtering by exponentially weighted moving average according to the following time recurrence relation:

5. The measuring and tracking device according to claim 1, wherein the adjustment means are configured using fuzzy logic in such a way as to:

distinguish N states of instantaneous trend of variation, N≥

2, each of these N states being associated with a predetermined corresponding value of high cutoff frequency of the low-pass filter and with a membership function with values in the interval [0;

1] defined in a range of possible values of instantaneous trend of variation, and

adjust the high cutoff frequency of the low-pass filter as a sum of the N predetermined values of high cutoff frequency respectively weighted by N degrees of membership of the estimated value of instantaneous trend of variation in each of the N states of instantaneous trend of variation, these degrees of membership being calculated using the N membership functions.

6. The measuring and tracking device according to claim 4, wherein N≥

3 and;

a first stable state is associated with a high cutoff frequency linked to a value of the exponential weighting coefficient α

between 0.9 and 1,

a second state of slow variation is associated with a high cutoff frequency linked to a value of the exponential weighting coefficient α

between 0.7 and 0.9,

a third state of fast variation is associated with a high cutoff frequency linked to a value of the exponential weighting coefficient α

between 0.1 and 0.3.

7. The measuring and tracking device according to claim 5, wherein each membership function is a Gaussian or piecewise linear function.

8. The measuring and tracking device according to claim 1, wherein the sensor is a gas sensor with a non-dispersive infrared emitter and a thermopile detector .

9. A method for measuring and tracking over time the quantity or concentration of a component in a fluid, comprising the following steps:

measuring a quantity or concentration of the component in the fluid and providing a quantitative signal for tracking this quantity or concentration over time, using a sensor,

processing the quantitative tracking signal using a low-pass filter,

providing the filtered quantitative signal at the output,

characterised in that the processing of the quantitative tracking signal comprises;

an estimation over time of an instantaneous trend of variation of the quantitative signal in a predetermined sliding time window, and

the adjustment over time of a high cutoff frequency of the low-pass filter according to the estimated instantaneous trend of variation.

10. A computer program downloadable from a communication network and/or recorded on a medium readable by computer and/or executable by a processor, comprising instructions for the execution of the following steps:

receiving a quantitative digital signal for tracking a quantity or concentration over time of a component in a fluid,

processing the quantitative tracking signal by low-pass filtering,

characterised in that the low-pass filtering is carried out using instructions for the execution of the following steps;

estimating over time an instantaneous trend of variation of the quantitative signal in a predetermined sliding time window, and

adjusting over time a high cutoff frequency of the low-pass filtering according to the estimated instantaneous trend of variation.