ACCELEROMETER DATA COMPRESSION

• US 20140046990A1
• Filed: 12/31/2010
• Published: 02/13/2014
• Est. Priority Date: 12/31/2010
• Status: Active Grant

• Current Assignee: Tomtom Global Content B.V (TomTom NV)
• Original Assignee: Nelson Miguel Da Cruz Goncalves
• Inventors: Kmiecik, Marcin Michal, Lai, Ying-Lin, Da Cruz Gonalves, Nelson Miguel
• Granted Patent: US 9,742,432 B2
• Time in Patent Office: Days
• US Class Current: 708/203
• CPC Class Codes: A61B 2503/10 Athletes
• CPC Class Codes: A61B 2560/0475 Special features of memory means, e.g. removable memory cards
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 2562/227 Sensors with electrical connectors
• CPC Class Codes: A61B 5/1112 Global tracking of patients, e.g. by using GPS
• CPC Class Codes: A61B 5/681 Wristwatch-type devices
• CPC Class Codes: A61B 5/7232 involving compression of the physiological signal, e.g. to extend the signal recording period
• CPC Class Codes: G01C 22/006 Pedometers
• CPC Class Codes: H03M 7/30 Compression speech analysis-synthesis for redundancy reduction G10L19/00; for image communication H04N; Expansion; Suppression of unnecessary data, e.g. redundancy reduction

Abstract

A method of compressing data output from an acceleration measurement means configured to be transported, carried or worn by a user is provided. Acceleration values indicative of the movement of the user are measured at a first frequency and values representative of the measured acceleration values are generated at a second frequency, which is lower than the first frequency. The step of generating comprises: defining a plurality of time windows, each time window containing a plurality of measured acceleration values; and applying a transformation to the measured acceleration values within each time window to generate a plurality of transformed values. For each time window, storing at least one of said plurality of transformed values and/or one or more parameters associated therewith.

Claims

1. A method of compressing data output from an acceleration measurement means configured to be transported, carried or worn by a user, comprising the steps of:

measuring acceleration values indicative of the movement of the user at a first frequency;

generating values representative of the measured acceleration values at a second frequency, which is lower than the first frequency, said step of generating comprising;

defining a plurality of time windows, each time window containing a plurality of measured acceleration values; and

applying a transformation to the measured acceleration values within each time window to generate a plurality of transformed values; and

,

for each time window, storing at least one of said plurality of transformed values and/or one or more parameters associated therewith.

2. A method as claimed in claim 1, wherein the acceleration values are measured using one or more accelerometers.

3. A method as claimed in claim 1, wherein the first frequency is between 1 Hz and 20 Hz.

4. A method as claimed in claim 1, wherein the acceleration values are stored in a data buffer.

5. A method as claimed in claim 1, further comprising determining an absolute acceleration value indicative of the movement of the user from the measured acceleration values.

6. A method as claimed in claim 1, wherein the plurality of time windows are defined such that a portion of one time window overlaps a portion of an adjacent time window.

7. A method as claimed in claim 1, wherein the second frequency is between 0.1 and 2 Hz.

8. A method as claimed in claim 1, wherein transformation applied to the measured acceleration values comprises a fast Fourier transformation.

9. A method as claimed in claim 1, comprising:

applying a transformation to the acceleration values within each time window to generate a frequency spectrum; and

storing one or more parameters associated with the frequency spectrum.

10. A method as claimed in claim 9, wherein the one or more parameters associated with the frequency spectrum comprise at least one of:

one or more indexed coefficients; and

one or more parameters derived from the indexed coefficients.

11. A method as claimed in claim 10, wherein said one or more parameters are selected from the group consisting of:

(i) the zero index amplitude;

(ii) the largest nonzero index amplitude;

(iii) the index associated with the largest amplitude; and

(iv) the sum of all the non-zero index amplitudes.

12. A system configured to be transported, carried or worn by a user, comprising:

one or more accelerometers for measuring acceleration values indicative of the movement of the user and/or device at a first frequency;

at least one processor arranged to generate values representative of the measured acceleration values at a second frequency, which is lower than the first frequency, by;

defining a plurality of time windows, each time window containing a plurality of measured acceleration values; and

applying a transformation to the measured acceleration values within each time window to generate a plurality of transformed values; and

at least one data storage device for storing, for each time window, at least one of said plurality of transformed values and/or one or more parameters associated therewith.

13. A system as claimed in claim 12, wherein said one or more accelerometers comprise a three-axis accelerometer.

14. A system as claimed in claim 12, further comprising a global navigation satellite system (GNSS) receiver for determining the location of the user.

15. A system as claimed in claim 12, wherein the system is a portable personal training device comprising a housing having a strap for securing the device to a user.

16-17. -17. (canceled)