Methods and system for obtaining a force measurement with reduced drift effects

Patent metadata

Field	Value
Publication number	US-10801882-B2
Application number	US-201816194093-A
Country	US
Kind code	B2
Filing date	Nov 16, 2018
Priority date	Nov 16, 2018
Publication date	Oct 13, 2020
Grant date	Oct 13, 2020

Abstract

Various methods and systems are provided for a drift-compensated force measurement. In one example, a method includes obtaining a single output voltage measurement from a strain gauge of an infant scale, the single output voltage reflective of a weight applied to the scale; obtaining a voltage measurement across each of four resistors of the strain gauge to determine four separate voltage measurements and determining a drift voltage based on the four separate voltage measurements; and outputting a corrected weight value determined based on a difference between the single output voltage and the drift voltage

First claim

The invention claimed is:

1. A method, comprising:
obtaining a single output voltage measurement from a strain gauge of a scale, the single output voltage reflective of a weight applied to the scale;
obtaining a voltage measurement across each of four resistors of the strain gauge to determine four separate voltage measurements and determining a drift voltage based on the four separate voltage measurements; and
outputting a corrected weight value determined based on a difference between the single output voltage and the drift voltage.

2. The method of claim 1 , further comprising storing the four separate voltage measurements as baseline voltages in response to receiving a first taring input indicating a request to zero the scale.

3. The method of claim 2 , wherein determining the drift voltage includes subtracting each stored baseline voltage from a corresponding one of the four separate voltage measurements, for each of the four resistors.

4. The method of claim 3 , further comprising updating the stored baseline voltages upon receiving a subsequent, second taring input, a duration after receiving the first taring input, indicating a request to re-zero the scale and, following receiving the second taring input, determining the drift voltage based on the updated, stored baseline voltages and newly obtained voltage measurements across each of the four resistors.

5. The method of claim 1 , wherein obtaining the voltage measurement across each of four resistors of the strain gauge to determine four separate voltage measurements includes obtaining the voltage measurement across each of the four resistors at the same time as obtaining the single output voltage measurement, each of the four separate voltage measurements and the single output voltage measurement taken between a different two points on the strain gauge.

6. The method of claim 1 , wherein the strain gauge includes a wheatstone bridge circuit including the four resistors with a node arranged between each set of two adjacently arrange resistors, the wheatstone bridge circuit having four nodes.

7. The method of claim 6 , wherein obtaining the single output voltage measurement includes measuring the single output voltage between a first node and second node of the four nodes and further comprising supplying an excitation voltage to the wheatstone bridge circuit between a third node and fourth node of the four nodes.

8. The method of claim 1 , wherein outputting the corrected weight value includes continuously outputting the corrected weight value to a display.

9. The method of claim 8 , wherein the display is a display of the scale and wherein the scale is an infant scale.

10. A method, comprising:
obtaining a force measurement from a strain gauge including a wheatstone bridge;
receiving individual voltage measurements across each of four resistors of the wheatstone bridge;
determining a drift term based on a sum of the individual voltage measurements for the four resistors; and
outputting to a display a corrected force measurement, the corrected force measurement obtained by subtracting the determined drift term from the received force measurement.

11. The method of claim 10 , wherein obtaining the force measurement includes determining the force measurement from a output voltage received from the wheatstone bridge, the output voltage measured across two points of the wheatstone bridge, a first point of the two points coupled to a first resistor and third resistor of the four resistors and a second point of the two points coupled to a second resistor and fourth resistor of the four resistors.

12. The method of claim 11 , further comprising supplying a supply voltage to the wheatstone bridge via applying the supply voltage across two different points of the wheatstone bridge, a first point of the two different points coupled to the first resistor and second resistor and a second point of the two different points coupled to the third resistor and fourth resistor.

13. The method of claim 10 , further comprising storing the received individual voltage measurements across each of the four resistors as baseline voltages in response to receiving an initial taring input and determining the drift term based on subsequently received individual voltage measurements and the stored baseline voltages.

14. The method of claim 13 , wherein determining the drift term includes determining the drift term based on the received individual voltage measurements and the baseline voltages, where the same baseline voltages are used even as the received individual voltage measurements change, until a second taring input is received.

15. The method of claim 11 , wherein the corrected force measurement is a weight and the wheatstone bridge is coupled to a beam of an infant scale.

16. A system for continuously measuring a weight of an infant, comprising:
a display; and
a control unit communicatively coupled to the display and including instructions stored in memory executable by a processor of the control unit to:
acquire an output voltage from a strain gauge of a scale, the strain gauge including a wheatstone bridge with four resistors, the output voltage indicative of a change in force applied to the scale;
acquire four individual voltages, each of the four individual voltages acquired across a different one of the four resistors;
determine a drift voltage from the acquired four individual voltages;
determine a drift-compensated weight value based on a difference between the acquired output voltage and the determined drift voltage; and
displaying the determined drift-compensated weight value via the display.

17. The system of claim 16 , wherein the instructions are further executable by the processor to: determine a baseline voltage across each of the four resistors in response to receiving a taring input requesting that the scale is tared and, following receiving the taring input, subtracting the baseline voltage for each of the four resistors from a corresponding one of the acquired four voltages to determine the drift voltage.

18. The system of claim 16 , wherein the instructions are further executable by the processor to: supply an excitation voltage to a first two nodes of the wheatstone bridge while the output voltage is acquired from a different, second two nodes of the wheatstone bridge.

19. The system of claim 16 , wherein the scale is an infant scale.

20. The system of claim 16 , wherein the four individual voltages are acquired at the same time as the output voltage.

Assignees

• Gen Electric

Inventors

• Khair Mohammad Mohammad

Classifications

• G01G23/3714 Primary

  with feedback means · CPC title

• G01G3/142

  Circuits specially adapted therefor · CPC title

• G01G23/163

  involving digital counting · CPC title

• G01G19/445

  in a horizontal position · CPC title

• A61G7/0527

  Weighing devices · CPC title