Baseline signal calculation

Patent metadata

Field	Value
Publication number	US-11513019-B2
Application number	US-202017128676-A
Country	US
Kind code	B2
Filing date	Dec 21, 2020
Priority date	Dec 21, 2020
Publication date	Nov 29, 2022
Grant date	Nov 29, 2022

Abstract

A baseline unit for use in a sensor system, the sensor system comprising N force sensors which output N sensor signals, respectively, where N≥1, the baseline unit configured to: monitor a measure of a rate of change of a sensor test signal, the sensor test signal being one of said N sensor signals or a signal derived from one or more of said N sensor signals; and in dependence upon the measure of the rate of change, control a stored baseline setting to control how a baseline test signal is calculated from said N sensor signals using a baseline-calculation method, the baseline-calculation method configured by the currently-stored baseline setting.

First claim

The invention claimed is:

1. A baseline unit for use in a sensor system, the sensor system comprising N force sensors which output N sensor signals, respectively, where N≥1, the baseline unit configured to:
monitor a measure of a rate of change of a sensor test signal, the sensor test signal being one of said N sensor signals or a signal derived from one or more of said N sensor signals; and
in dependence upon the measure of the rate of change, control a stored baseline setting to control how a baseline test signal is calculated from said N sensor signals using a baseline-calculation method, the baseline-calculation method configured by the currently-stored baseline setting.

2. The baseline unit as claimed in claim 1 , configured to:
monitor a difference between the sensor test signal and the baseline test signal as the measure of the rate of change of the sensor test signal; and
control the stored baseline setting in dependence upon the difference to control how the baseline test signal is calculated from said N sensor signals.

3. The baseline unit as claimed in claim 1 , configured to set the stored baseline setting at different values for different ranges of the measure.

4. The baseline unit as claimed in claim 1 , configured to change the stored baseline setting when a defined change condition is met.

5. The baseline unit as claimed in claim 4 , wherein said change condition comprises an increase in the measure to a value above a threshold.

6. The baseline unit as claimed in claim 5 , wherein:
the measure and the threshold are signed values, and the baseline unit is configured to determine that the measure exceeds the threshold when the measure and the threshold have the same sign as one another and the magnitude of the measure is larger than the magnitude of the threshold; or
the baseline unit is configured to determine that the measure exceeds the threshold when an absolute value of the measure is larger than an absolute value of the threshold.

7. The baseline unit as claimed in claim 5 , wherein said change to the stored baseline setting is a first change from a below-threshold value to an above-threshold value, and wherein the baseline unit is configured to:
after making said first change to the baseline setting, determine whether at least one defined further-change condition is met; and
when it is determined that a further-change condition is met, further change the stored baseline setting,
optionally wherein at least one said further change changes the stored baseline setting to a value closer to the below-threshold value or to the below-threshold value.

8. The baseline unit as claimed in claim 7 , wherein said threshold is a first threshold, and wherein each further-change condition comprises:
the expiry of a defined time period, optionally measured from when the first change is made or from when the preceding change is made; and/or
an increase in the measure to a value above a second threshold; and/or
a reduction in the measure to a value below a third threshold; and/or
a reduction in temporal variance or jitter in the sensor test signal, or in any of the sensor signals, from a high value above a corresponding temporal-variance threshold to a low value below that temporal-variance threshold.

9. The baseline unit as claimed in claim 1 , wherein:
the baseline-calculation method comprises low-pass filtering defined by a filter parameter; and
the baseline setting defines a value of the filter parameter;
optionally wherein the filter parameter comprises a time constant, a forgetting factor and/or a corner frequency which defines the low-pass filtering, such as a passband of the low-pass filtering.

10. The baseline unit as claimed in claim 9 , configured, when the measure exceeds a threshold, to change the stored baseline setting to change a size of the passband of the low-pass filtering from a first size to a second size, smaller in frequency bandwidth than the first size,
optionally wherein the second size is sufficient to substantially maintain a value of the baseline test signal or to reduce a rate of change of the baseline test signal, optionally to substantially zero.

11. The baseline unit as claimed in claim 9 , configured, when the measure exceeds a threshold, to change the stored baseline setting to a setting which disables or overrides an output of the low-pass filtering and substantially maintains a value of the baseline test signal.

12. The baseline unit as claimed in claim 1 , wherein the sensor test signal is the sensor signal for a given force sensor of the sensor system or a signal derived therefrom, and the baseline unit is configured to calculate the baseline test signal as a baseline signal for that force sensor from the sensor test signal using the baseline-calculation method.

13. The baseline unit as claimed in claim 1 , wherein:
N≥2;
values of the baseline setting each comprise component values per force sensor; and
the baseline unit is configured, for each force sensor, to calculate its baseline signal using the baseline-calculation method as configured by its corresponding component value of the currently-stored baseline setting.

14. The baseline unit as claimed in claim 12 , wherein:
N≥2;
the given force sensor is a first force sensor of the sensor system; and
the baseline unit is configured to calculate a baseline signal for a second force sensor of the sensor system from its sensor signal using the baseline-calculation method or a method derived therefrom.

15. The baseline unit as claimed in claim 1 , configured to calculate the sensor test signal based on a combination of the N sensor signals, where N≥2.

16. The baseline unit as claimed in claim 15 , configured to calculate the baseline test signal from the sensor test signal using the baseline-calculation method; and/or
calculate a baseline signal for at least one of the force sensors from its sensor signal using the baseline-calculation method.

17. The baseline unit as claimed in claim 15 , configured to:
calculate a baseline signal for each of the force sensors from its sensor signal using the baseline-calculation method; and
calculate the baseline test signal based on a combination of the N baseline signals;
optionally wherein:
the baseline test signal is based on a sum or average of the N baseline signals; and/or
the sensor test signal is based on a sum or average of the N sensor signals.

18. The baseline unit as claimed in claim 17 , wherein:
the N sensor signals define a sensor test vector in N-dimensional space;
the N baseline signals define a baseline test vector in the N-dimensional space; and
the baseline unit is configured to determine a difference between the sensor test signal and the baseline test signal as the measure of the rate of change of the sensor test signal based on a distance such as a Euclidean distance between respective locations in the N-dimensional space defined by the sensor test vector and the baseline test vector.

19. The baseline unit as claimed in claim 14 , wherein the baseline unit is configured to:
apply a signal-conditioning process to the N sensor signals to generate N conditioned sensor signals, respectively;
calculate the baseline test signal from said N conditioned sensor signals; and
derive the sensor test signal from said N conditioned sensor signals;
optionally wherein the signal-conditioning process comprises removing the common mode from the N sensor signals.

20. A baseline unit for use in a sensor system, the sensor system compr

Assignees

• Cirrus Logic Int Semiconductor Ltd
• Cirrus Logic Inc

Inventors

• Lindemann Eric
• Peso Parada Pablo
• Rosenthal Tanner
• Maru Siddharth

Classifications

• G06F3/04144

  using an array of force sensing means (position sensing using the local deformation of sensor cells G06F3/0447) · CPC title

• G01D18/004 Primary

  Continuous recalibration · CPC title

• G01L5/228

  using tactile array force sensors · CPC title

• G01D18/008

  with calibration coefficients stored in memory · CPC title

• G01L25/00 Primary

  Testing or calibrating of apparatus for measuring force, torque, work, mechanical power, or mechanical efficiency · CPC title