Granted Patent B2

US 12,730,018 · App. 18/256,110 · Granted Sep 8, 2026

Inventors: Piao Huang (Paris, FR); Damien Jacobs (Paris, FR)

Assignee: RXFUNCTION, INC.

G01L1/146A61B5/1038A61B5/6807G01L25/00A61B2560/0223A61B2562/0247

Abstract

Claims (42)

1 . A pressure sensor comprising:

a measurement portion comprising a plurality of capacitive pressure sensors; and

a chip portion comprising:

(i) a memory comprising a set of dynamic calibration curves of the plurality of capacitive pressure sensors, the dynamic calibration curve being a response to an input;

(ii) a measuring unit electrically connected to the plurality of capacitive pressure sensors; and

(iii) a computing unit configured to compute pressure related data on the basis of the measurements of the plurality of capacitive pressure sensors and the dynamic calibration curves.

2 . The pressure sensor according to claim 1 , wherein each dynamic calibration curve is defined by a predetermined rate of variation of the input.

3 . The pressure sensor according to claim 1 , wherein the set of dynamic calibration curves comprise one dynamic calibration curve for each sensor of the plurality of capacitive pressure sensor.

4 . The pressure sensor according to claim 1 , wherein the dynamic calibration curves are polynomial fits of capacitance values as a function of the input on the plurality of capacitive pressure sensor.

5 . The pressure sensor according to claim 4 , wherein the input is a time-dependent input varying over time at a gait simulating rate.

6 . The pressure sensor according to claim 4 , wherein the input is a force, a pressure or a displacement.

7 . The pressure sensor according to claim 1 , wherein the measurement portion extends over a measurement surface having a surface boundary, and wherein the computing unit is further configured to:

(i) determine a sensor boundary, the sensor boundary being a curve surrounding some or the plurality of capacitive pressure sensors and comprised within the surface boundary of the measurement surface;

(ii) apply a first boundary condition to the surface boundary and a second boundary condition to the sensor boundary, said second boundary condition being different from the first boundary condition; and

(iii) compute a field of pressure over the measurement surface, by interpolation on the basis of: the pressure related data, the first boundary condition, and the second boundary condition.

8 . The pressure sensor according to claim 7 , wherein the first boundary condition is a pressure equal to 0 kg·cm −2 at the surface boundary.

9 . An insole for insertion into an article of footwear, the insole comprising a pressure sensor according to claim 1 .

10 . A calibration system, the system comprising an insole according to claim 9 and a calibration unit configured to:

apply an input to at least one capacitive pressure sensor, the input being time-dependent during an interval of time Δt;

measure the capacitance of the at least one capacitive pressure sensor during the interval of time Δt; and

determine a dynamic calibration curve of the at least one capacitive pressure sensor based on the input and the measured capacitance;

wherein the input is a force, a pressure or a displacement.

11 . A computer-implemented method for determining the total normal force applied on a pressure sensor according to claim 1 , comprising the steps of:

a) receiving the dynamic calibration curves of the plurality of capacitive pressure sensors;

b) measuring the capacitance of each sensor of the plurality of capacitive pressure sensors over a measurement surface included in the measurement portion;

c) for each sensor of the plurality of capacitive pressure sensors, converting the measured capacitance into a pressure value on the basis of the dynamic calibration curve of the plurality of capacitive pressure sensors;

d) computing a field of pressure over the measurement surface based on the pressure values obtained in the converting step c); and

e) computing the total normal force applied on the pressure sensor on the basis of the field of pressure.

12 . The method according to claim 11 , wherein the step d) of computing the field of pressure further comprises the following sub-steps:

d.1) determining a sensor boundary, the sensor boundary being a curve comprised within the surface boundary of the measurement surface and surrounding the plurality of capacitive pressure sensors;

d.2) applying a first boundary condition to the surface boundary and a second boundary condition to the sensor boundary;

d.3) computing the field of pressure over a portion of the measurement surface included within the sensor boundary;

d.4) computing the field of pressure over the measurement surface, by interpolation on the basis of the field of pressure over a portion of the measurement surface, the first and second boundary conditions.

13 . The method according to claim 12 , wherein the application step d.2) comprises: applying, as a first boundary condition, a pressure P1 equal to 0 kg·cm −2 and applying, as a second boundary condition, a pressure P2 obtained via the following steps:

selecting a set of sensors from the plurality of capacitive pressure sensors based on a criterion of proximity to the sensor boundary;

calculating a pressure gradient for the selected set of sensors; and

calculating a pressure P2 at the sensor boundary based on the pressure gradient and on the pressure values of the selected set of sensors obtained in the converting step c).

14 . The method according to claim 11 , wherein the step d) of computing the field of pressure over the measurement surface comprises the following steps:

computing a discrete field of pressure on the basis of the pressure values obtained in the converting step c); and

applying an interpolation function to the discrete field of pressure so as to obtain a continuous field of pressure;

wherein the step e) of computing the total normal force comprises integration of the continuous field of pressure over the measurement surface.

15 . The method according to claim 14 , wherein the interpolation function is a linear function.

Assignments (2)

Priority Claims (1)

Continuity (1)

References Cited (104)