Wearable system and method for sensing and monitoring a swimming activity of a user

Patent metadata

Field	Value
Publication number	US-12357874-B2
Application number	US-202117466553-A
Country	US
Kind code	B2
Filing date	Sep 3, 2021
Priority date	Sep 9, 2020
Publication date	Jul 15, 2025
Grant date	Jul 15, 2025

Abstract

A system can be used for detecting execution of a swimming activity of a user. The system includes a processing unit, a buffer, and an electrostatic-charge-variation sensor configured to sense a variation of electrostatic charge of the user during execution of the swimming activity and to generate a corresponding charge-variation signal. The processing unit is configured to acquire the charge-variation signal, detect a first sub-portion of signal that identifies a basic movement of the swimming activity in the charge-variation signal, store the first sub-portion of signal in the buffer, compute an auto-correlation between the first sub-portion of signal stored in the buffer and a second sub-portion of signal of the charge-variation signal, and detect the presence of the basic movement in the second sub-portion of signal based on a result of the auto-correlation.

First claim

What is claimed is:

1. A system for detecting execution of a swimming activity of a user, the system comprising:
an electrostatic-charge-variation sensor configured to sense a variation of electrostatic charge of the user during the execution of the swimming activity and to generate therefrom a charge-variation signal; and
a microcontroller coupled to the electrostatic-charge-variation sensor and configured to:
acquire the charge-variation signal from the electrostatic-charge-variation sensor;
detect a first sub-portion of signal in the charge-variation signal, the first sub-portion of signal identifying a basic movement of the swimming activity;
store the first sub-portion of signal in a buffer;
compute an auto-correlation between the first sub-portion of signal stored in the buffer and a second sub-portion of signal of the charge-variation signal, the second sub-portion of signal being temporally subsequent to the first sub-portion of signal;
detect a presence of the basic movement in the second sub-portion of signal based on a result of the auto-correlation;
identify a specific swimming style of the basic movement by analyzing the first or second sub-portions of signal, the specific swimming style selected from a group of swimming styles that generate a respective periodic electrostatic-charge-variation signal; and
increase a counter in response to detecting the basic movement in the second sub-portion of signal.

2. The system according to claim 1 , wherein the microcontroller is further configured to analyze the first and second sub-portions of signal in order to identify the specific swimming style.

3. The system according to claim 1 , wherein the microcontroller is configured to detect the presence of the basic movement by determining that the computation of the auto-correlation yields a value equal to or greater than a predefined comparison threshold.

4. The system according to claim 1 , wherein the microcontroller is configured to select the second sub-portion of signal using a sliding window.

5. The system according to claim 4 , wherein the charge-variation signal is time-variable and the sliding window is designed to slide along the charge-variation signal with discrete steps corresponding to successive instants, as long as the result of the auto-correlation confirms the presence of the basic movement.

6. The system according to claim 5 , wherein the sliding window has a predefined temporal dimension and delimits a respective intermediate portion of signal at each discrete step, the auto-correlation being computed between the first sub-portion of signal and each intermediate portion of signal delimited by the sliding window at each discrete step, wherein the second sub-portion of signal corresponds to the charge-variation signal comprised in a time interval within which the sliding window is made to slide.

7. The system according to claim 5 , wherein the auto-correlation provides a binary value that is generated at each discrete step of sliding of the sliding window and is kept at a constant value as long as a result of a correlation between the first sub-portion of signal and each intermediate portion of signal delimited by the sliding window at each discrete step is greater than a predefined correlation threshold value.

8. The system according to claim 1 , wherein the microcontroller is further configured to:
detect a third sub-portion of signal in the charge-variation signal, the third sub-portion of signal being temporally subsequent to the second sub-portion of signal and identifying the basic movement;
replace the first sub-portion of signal with the third sub-portion of signal in the buffer;
compute the auto-correlation between the third sub-portion of signal stored in the buffer and a fourth sub-portion of signal of the charge-variation signal, the fourth sub-portion being temporally subsequent to the third sub-portion of signal; and
detect the presence of the basic movement in the fourth sub-portion of signal based on a result of the computation of the auto-correlation between the third sub-portion of signal and the fourth sub-portion of signal.

9. The system according to claim 1 , wherein the microcontroller is configured to detect the first sub-portion of signal by:
discretizing the charge-variation signal to generate a first plurality of discrete values;
storing a second plurality of the discrete values in the buffer, the second plurality smaller than the first plurality;
computing an average value of the second plurality of discrete values;
computing a standard deviation of the second plurality of discrete values;
computing an absolute value of a ratio between the standard deviation and the average value of the second plurality of discrete values; and
confirming a presence of the swimming activity when the absolute value is equal to or greater than a predefined threshold.

10. The system according to claim 9 , wherein the presence of the swimming activity is confirmed when the first sub-portion of signal comprises at least one subset of the second plurality of discrete values.

11. The system according to claim 9 , wherein the microcontroller is further configured to detect the first sub-portion of signal by:
determining that the absolute value is greater than the predefined threshold;
storing the second plurality of discrete values in a second buffer;
acquiring a new discrete value of the charge-variation signal;
updating the buffer by storing the new discrete value and eliminating a temporally oldest discrete value from the buffer;
computing an average value of the discrete values stored in the buffer after the updating;
computing a standard deviation of the discrete values stored in the buffer after the updating; and
storing the new discrete value in the second buffer when the absolute value computed using the updated buffer is greater than the predefined threshold.

12. The system of claim 11 , wherein the microcontroller is further configured to detect the first sub-portion of signal by:
repeating the acquiring the new discrete value, the updating the buffer, the computing the average value and the standard deviation of the discrete values stored in the buffer after the updating, and the storing the new discrete value in the second buffer as long as the absolute value computed using the updated buffer is greater than the predefined threshold; and
using a subset of discrete values stored in the second buffer as the first sub-portion of signal.

13. The system according to claim 1 , wherein the group of swimming styles consists of front crawl, breaststroke, and backstroke.

14. A method for detecting execution of a swimming activity of a user, the method comprising:
generating, by an electrostatic-charge-variation sensor, an electrostatic-charge-variation signal during the execution of the swimming activity;
acquiring, by a microcontroller, the electrostatic-charge-variation signal from the electrostatic-charge-variation sensor;
detecting, by the microcontroller, a first sub-portion of signal in the charge-variation signal, the first sub-portion of signal identifying a basic movement of the swimming activity;
storing, by the microcontroller, the first sub-portion of signal in a buffer;
computing, by the microcontroller, an auto-correlation between the first sub-portion of signal stored in the buffer and a second sub-portion of signal of the charge-variation signal, the second sub-portion of signal being temporally subsequent to the first sub-portion of signal;
detecting, by the microcontroller, a presence of the basic movement in the second sub-portion of signal based on a re

Assignees

• St Microelectronics Srl

Inventors

• Alessi Enrico Rosario
• Passaniti Fabio

Classifications

• A63B24/0062

  Monitoring athletic performances, e.g. for determining the work of a user on an exercise apparatus, the completed jogging or cycling distance · CPC title

• G06F2218/00

  Aspects of pattern recognition specially adapted for signal processing · CPC title

• G06F18/2115

  by evaluating different subsets according to an optimisation criterion, e.g. class separability, forward selection or backward elimination · CPC title

• A63B2244/20

  Swimming · CPC title

• A63B2220/836

  Sensors arranged on the body of the user · CPC title