Method for analysing irregularities in human locomotion

• US 20030139692A1
• Filed: 11/08/2002
• Published: 07/24/2003
• Est. Priority Date: 02/04/2000
• Status: Active Grant

• Current Assignee: Institut National de La Recherche Agronomique
• Original Assignee: Institut National de La Recherche Agronomique
• Inventors: Barrey, Eric, Auvinet, Bernard
• Granted Patent: US 6,895,341 B2
• Time in Patent Office: Days
• US Class Current: 600/595
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/061 Determining position of a probe within the body employing means separate from the probe, e.g. sensing internal probe position employing impedance electrodes on the surface of the body A61B1/00158 takes precedence
• CPC Class Codes: A61B 5/1038 Measuring plantar pressure during gait
• CPC Class Codes: A61B 5/726 using Wavelet transforms
• CPC Class Codes: A61B 5/743 Displaying an image simultaneously with additional graphical information, e.g. symbols, charts, function plots

Abstract

The invention relates to a method of analysis for human locomotion irregularities. In such method, acceleration measurements obtained during one or more motions controlled at a stabilised gait of a human being are used, through accelerometers measuring on a time base accelerations according to at least one direction, and any locomotion irregularities are analysed from reference measurements.

Such measured accelerations are submitted to at least one wavelet transformation and the resulting wavelet transform is used to detect and/or analyse the irregularities.

Claims

1. Method of analysis for human locomotion irregularities, wherein acceleration measurements obtained during at least one motion controlled at a stabilised gait of a human being are used, through at least one accelerometer measuring on a time base at least one acceleration according to at least one direction, by detecting and analysing any locomotion irregularities from reference measurements,

characterized in that said measured accelerations are submitted to at least one wavelet transformation and the resulting wavelet transform is used to detect and/or analyse said irregularities, and the spectrum of said wavelet transform is visualised in three dimensions, respectively, of time, frequency and spectral energy module of the wavelet transform to detect and analyse said irregularities.

2. Method of analysis according to claim 1, characterized in that the spectral energy module of the wavelet transform is represented by coloured contours or a colour gradient.

3. Method of analysis according to claim 2, characterized in that a linear scale for time and a logarithmic scale for frequency are used.

4. Method of analysis according to any one of preceding claims, characterized in that said wavelet transform is continuous.

5. Method of analysis according to claim 4, characterized in that said transform is a Morlet wavelet transform.

6. Method of analysis according to any one of preceding claims, characterized in that the wavelet transform having a time-dependant spectral energy, a low frequency band is defined in which the spectral energy for a regular locomotion is mainly concentrated and said irregularities are detected and/or analysed by using the spectral energy outside such band.

7. Method of analysis according to claim 6, characterized in that the band is comprised between 1 Hz and 4 Hz.

8. Method of analysis according to any one of claims 6 or 7, characterized in that irregularities are identified and/or analysed by locating and/or studying the spectral energy peaks (124-128, 155-158) exceeding said band.

9. Method of analysis according to any one of claims 6 to 8, characterized in that a locomotion irregularity degree is calculated by reporting the margin spectral energy outside said band to the total spectral energy.

10. Method of analysis according to any one of preceding claims, characterized in that said accelerations are at least in a number of two and in that, to detect and/or analyse the irregularities, at least one front butterfly (160) is also used representing the intensity of one of the measured accelerations depending on the intensity of another of the measured accelerations.

11. Method of analysis according to any one of preceding claims, characterized in that, to detect and/or analyse the irregularities, at least one representation (170, 180) in a phase space is also used, giving the intensity of at least one of said accelerations depending on the intensity of the time derivative of said acceleration or depending on said acceleration time shifted with a predetermined time (d).

12. Method of analysis according to claim 11, characterized in that at least one Lyapunov coefficient of said representation in the phase space, preferably the maximum Lyapunov coefficient, is calculated.

13. Method of analysis according to claim 12, characterized in that it is considered that a co-ordination disorder occurs if the maximum Lyapunov coefficient is higher than 0.4.

14. Application of the method of analysis according to any one of preceding claims for the medical field, in particular for the early detection of neuro-motor disorders of elderly people.

15. Application of the method of analysis according to any one of claims 1 to 13 for the sport field, in particular for detecting technical defects with sport walkers or runners.

16. Application of the method of analysis according to any one of claims 1 to 13 for detecting athlete'"'"'s stride particularities during a race period.

17. Application of the method of analysis according to any one of claims 1 to 13 for measuring and quantifying the biomechanical constraints associated to a disease of the locomotive apparatus.