Flow meter

Patent metadata

Field	Value
Publication number	US-10113660-B2
Application number	US-201815943238-A
Country	US
Kind code	B2
Filing date	Apr 2, 2018
Priority date	Dec 21, 2011
Publication date	Oct 30, 2018
Grant date	Oct 30, 2018

Abstract

A flow meter includes a background pattern disposed behind a drip chamber, an image sensor, and a processor. The image sensor has a field of view and is configured to view the drip chamber within the field of view. The processor is coupled to the image sensor to receive image data therefrom and captures, using the image sensor, an image of the drip chamber and at least a portion of the background pattern, examines the image, and adjusts a flow rate of fluid flowing through a fluid line in accordance with the examination of the image.

First claim

What is claimed is:

1. A method for adjusting a flow rate of a fluid line, the method comprising:
capturing an image of a drip chamber using an image sensor;
subtracting the image from a background image to thereby generate a difference image;
converting each pixel of the difference image to a first value where an absolute value of a respective pixel is beyond a predetermined threshold or to a second value where the absolute value of the respective pixel is less than the predetermined threshold to generate a converted difference image;
summing each row of the converted difference image to generate a plurality of summation values, wherein each summation value of the plurality of summation values corresponds to a respective row of the converted difference image;
examining a plurality of contiguous summation values within the plurality of summation values; and
adjusting a flow rate of fluid flowing through the fluid line in accordance with the examination of the plurality of contiguous summation values.

2. The method according to claim 1 , wherein the background image is generated using another image captured by the image sensor.

3. The method according to claim 1 , further comprising the act of estimating a volume of a drop using the image of the drip chamber and the background image.

4. The method according to claim 1 , further comprising the act of identifying a plurality of pixels of interest within the image.

5. The method according to claim 4 , wherein the plurality of pixels of interest are identified by comparing the image to the background image.

6. The method according to claim 4 , further comprising the act of determining a subset of pixels within the plurality of pixels of interest, wherein each pixel of the plurality of pixels of interest is determined to be within the subset of pixels when there is a path to a baseline corresponding to the drip chamber.

7. The method according to claim 4 , further comprising the act of determining a volume of a drop based upon the plurality of pixels of interest.

8. The method according to claim 1 , further comprising the act of initializing the background image.

9. The method according to claim 1 , further comprising the act of updating the background image using the image captured by the image sensor.

10. The method according to claim 9 , wherein the background image is updated in accordance with:
P background,i,j =P background,i,j (1−α background )+α background P input,i,j .

11. The method as in claim 1 , further comprising the act of updating an array of variances using the image captured by the image sensor.

12. The method according to claim 11 , wherein the array of variances is updated in accordance with:
σ temp 2 =( P background,i,j −P input,i,j ) 2

σ background,i,j 2 =σ background,i,j 2 (1−β background )+β background σ temp 2 .

13. The method according to claim 1 , further comprising the act of updating an array of integers in accordance with the image captured by the image sensor.

14. The method according to claim 13 , wherein each integer of the array of integers corresponds to a number of updates of a pixel of the background image.

15. The method according to claim 14 , wherein a comparison of the image to the background image only compares pixels within the image to pixels within the background image where a respective integer of the array of integers indicates a respective pixel within the background image has been updated at least a predetermined number of times.

16. The method according to claim 1 , further comprising the acts of:
identifying a drop in the image and a predetermined band near an edge of the drop; and
initializing the background image by setting each pixel of the background image to the image unless it is within the identified drop or the predetermined band near the edge of the drop.

17. The method according to claim 16 , further comprising the act of setting a pixel of the background image to a predetermined value where a corresponding pixel of the image is within the identified drop or the predetermined band near the edge of the drop.

18. The method according to claim 17 , wherein the corresponding pixel of the image has a location corresponding to a location of the pixel of the background image.

19. The method according to claim 1 , further comprising the act of determining a baseline corresponding to an opening of the drip chamber.

20. The method according to claim 1 , wherein an act of determining a subset of pixels within a plurality of pixels of interest that corresponds to a drop includes determining each of the plurality of pixels of interest is within the subset of pixels where the respective pixel of the plurality of pixels of interest has a contiguous path back to a baseline of the drop forming at an opening of the drip chamber.

21. The method according to claim 1 , further comprising the acts of:
identifying a drop within the image and a predetermined band near an edge of the drop;
initializing the background image by setting each pixel to the image unless it is within the identified drop or the predetermined band near the edge of the drop;
setting pixels within the region of the drop or within the predetermined band to a predetermined value;
initializing an array of integers; and
initializing an array of variances.

22. The method according to claim 21 , further comprising the act of updating the background image, the array of integers, and the array of variances using the image.

23. The method according to claim 1 , further comprising the act of adjusting a valve to control the flow rate.

24. The method according to claim 1 , wherein the background image is configured to filter out low frequency artifacts.

25. The method according to claim 1 , wherein the act of examining the plurality of contiguous summation values includes determining a free flow condition exists by determining the plurality of contiguous summation values is above another predetermined threshold.

26. The method according to claim 1 , wherein act of examining the plurality of contiguous summation values includes determining a drop has been formed within the drip chamber.

27. The method according to claim 26 , wherein the act of determining the drop has been formed within the drip chamber includes determining the plurality of contiguous summation values is within a predetermined range greater than a minimum value and less than a maximum value.

28. The method according to claim 1 , further comprising the act of converting each pixel of the difference image to a squared value of each pixel after the subtracting act and prior to the converting act.

29. The method according to claim 1 , further comprising the acts of:
creating a first thresholded image from the image by comparing each pixel of the image to a threshold value;
determining a set of pixels within the first thresholded image connected to a predetermined set of pixels within the first thresholded image;
filtering all remaining pixels of the first thresholded image that are not within the set of pixels, the filtering operates on a pixel-by-pixel basis within the time domain to generate a first filtered image;
removing pixels determined to not be part of a drop from the first thresholded image using the first filtered image to generate a second image;
determining a

Assignees

• Deka Products Lp

Inventors

• Peret Bob D
• Kane Derek G
• Kamen Dean
• Murphy Colin H
• Kerwin John M

Classifications

• G06T7/20

  Analysis of motion (motion estimation for coding, decoding, compressing or decompressing digital video signals H04N19/43, H04N19/51) · CPC title

• A61M5/1411 Primary

  Drip chambers (A61M5/162, A61M5/1689, A61M5/40 take precedence) · CPC title

• G06V10/761

  Proximity, similarity or dissimilarity measures · CPC title

• G06V10/75

  Organisation of the matching processes, e.g. simultaneous or sequential comparisons of image or video features; Coarse-fine approaches, e.g. multi-scale approaches; using context analysis; Selection of dictionaries · CPC title

• G06F18/22

  Matching criteria, e.g. proximity measures · CPC title