PORTABLE DEVICE AND METHOD FOR MEASUREMENT AND CALCULATION OF DYNAMIC PARAMETERS OF PEDESTRIAN LOCOMOTION

• US 20100280792A1
• Filed: 09/25/2008
• Published: 11/04/2010
• Est. Priority Date: 01/17/2008
• Status: Abandoned Application

• Current Assignee: Kinematix Sense, S.A., Tomorrow Options - Microelectronics, S.A., Universidade D.O. Porto
• Original Assignee: Kinematix Sense, S.A., Universidade D.O. Porto
• Inventors: Paiva Velhote Correia, Miguel Fernando, Reis Cunha, Sérgio
• Application Number:
  US12/812,438
• Publication Number:
  US 20100280792A1
• Time in Patent Office: Days
• US Class Current: 702/160
• CPC Class Codes: A61B 5/1038 Measuring plantar pressure during gait
• CPC Class Codes: G01C 22/006 Pedometers

Abstract

The disclosed subject matter relates to a portable and autonomous device and corresponding method for the measurement, recording and calculation of dynamic parameters of the pedestrian locomotion of its bearer. The method hereby disclosed allows determining the distance effectively travelled, the velocity of displacement and the pressures exerted on the contact surface of the lower limb with the ground, during the pedestrian locomotion, according to its different phases. Through sensors strategically placed, accelerations, angular velocities and pressures are measured and recorded on the control unit. The device disclosed includes a processing unit that implements the method disclosed and a communication unit to transfer to an external unit the calculated parameters. The disclosed invention can be used in applications that involve monitoring parameters of the locomotion activity or daily ambulation of its bearer, in the areas of health and sports or in any physical and occupational activities.

Claims

1. Method for the measurement and calculation of dynamical parameters of pedestrian locomotion comprising:

filtering measurements of angular velocity of a single-axis gyroscope by means of a low-pass filter, in order to continuously determine the drift of this sensor;

integrating the difference, between the gyroscope signal and said drift, obtaining the angle, θ

, of orientation with respect to the horizontal and vertical axis, of the referential defined by the axes of at least two single-axis accelerometers, or analogously at least one double-axis accelerometer;

converting the accelerometers measurements to a new referential by a rotation, said rotation obtained from said angle, θ

, of orientation, where, in the new referential, one of the axis is horizontal and the other vertical;

integrating the accelerometer measurements over time to obtain the horizontal and vertical velocities;

integrating the measurements of horizontal and vertical velocities in order to obtain the horizontal and vertical components of position;

estimating the offset, Δ

θ

, of the angle θ

, and the vertical offset, Δ

A_v, of the vertical acceleration A_v, or the horizontal offset, Δ

A_h, of the horizontal acceleration A_h, and the errors, Δ

V_h and Δ

V_v, respectively, in horizontal and vertical velocities, V_h and V_v;

with said offsets and errors being used as state variables of an extended discrete Kalman filter;

updating the state of said Kalman filter every time two or more force sensors indicate the lower limb is in contact with the ground, exerting a pressure p above a threshold high enough to consider that said limb'"'"'s velocity is zero, in the form of state observation of null velocities V_h and V_v;

recording the series of activations of the force sensors to determine the locomotion cycles;

recording force sensor data and the instants when they occur within the locomotion cycle for the detection of eventual abnormalities.

2. Method for the measurement and calculation of dynamical parameters of pedestrian locomotion, according to claim 1, wherein the accelerometers and the gyroscope are placed in a manner that is solid with the lower limb of the bearer, such that the plane of movement, defined by the axes of the accelerometers, is parallel to the sagital plane of the individual.

3. Method for the measurement and calculation of dynamical parameters of pedestrian locomotion, according to claim 1, wherein the low-pass filter has a cut-off frequency below the frequencies that characterize the bearer locomotion movement, compensating the drift in angular velocity of the lower limb as measured by the gyroscope.

4. Method for the measurement and calculation of dynamical parameters of pedestrian locomotion, according to claim 1, wherein, automatically and in real time, the pressure exerted in each of the several critical points on the support surface of the lower limb is analyzed, according to the phases of the pedestrian locomotion cycle, where the values determined are the time averages and maximum of sampled pressures at each location, also recording the instant, within the locomotion cycle, when the pressures occurred.

5. Method for the measurement and calculation of dynamical parameters of pedestrian locomotion, according to claim 1, wherein the number of steps, the traveled distance, the velocity and the acceleration of the lower limb, the average stride length and duration, the average amplitude of movement of the lower limb, as well as the format of the average stride in terms of the durations of each of its constituents phases, are recorded or transmitted in real-time.

6. Method for the measurement and calculation of dynamical parameters of pedestrian locomotion, according to claim 5, wherein the referred parameters are calculated for each continuous uninterrupted sequence of locomotion cycles.

7. Device for the measurement and calculation of dynamical parameters of pedestrian locomotion, comprising the following elements:

two single-axis accelerometers, or analogously one double-axis accelerometer;

one single-axis gyroscope;

at least two force sensors, suitable for determining when there is full contact of the lower limb with the ground

one recursive self-calibrating estimator of corrections to the horizontal and vertical velocities of the device, said estimator being self-calibrating when there is full contact of the lower limb with the ground and when, therefore, velocities are null.

8. Device for the measurement and calculation of dynamical parameters of pedestrian locomotion according to claim 7, further comprising:

a rotation operator connected to the accelerometers and gyroscope, suitable for converting their output data to horizontal and vertical directions;

a first set of two integrators, connected to the accelerometers, which output the estimated horizontal and vertical velocities of the device;

a second set of two integrators, connected to the output of the first set, which output the estimated horizontal and vertical positions;

an extended kalman filter, as the said recursive self-calibrating estimator.

9. Device for the measurement and calculation of dynamical parameters of pedestrian locomotion, according to claim 7, wherein the accelerometers axes are oriented parallel to a plane of movement and aligned orthogonally to each other.

10. Device for the measurement and calculation of dynamical parameters of pedestrian locomotion, according to claim 7, wherein the sensing axis of the gyroscope is perpendicular to the plane of movement.

11. Device for the measurement and calculation of dynamical parameters of pedestrian locomotion, according to claim 7, further including force sensors, for measurement of pressure in several anatomic or pathologically relevant points.

12. Device for the measurement and calculation of dynamical parameters of pedestrian locomotion, according to claim 11, wherein the force sensors are piezo-resistive.

13. Device for the measurement and calculation of dynamical parameters of pedestrian locomotion, according to claim 7 wherein the two accelerometers and the gyroscope are placed in a manner that is solid with the lower limb of the bearer, such that the plane of movement defined by the axes of the accelerometers is parallel to the sagital plane of the individual.

14. Device for the measurement and calculation of dynamical parameters of pedestrian locomotion, according to claim 7, further comprising a data processing module to automatically and in real time analyse the pressure exerted in each of the several critical points on the support surface of the lower limb, according to the phases of the pedestrian locomotion cycle, where the values determined are the profile, average and maximum pressures at each location, with reference to the mean instant, within the locomotion cycle, when said pressures occurred.

15. Device for the measurement and calculation of dynamical parameters of pedestrian locomotion, according to claim 14, wherein the data processing module is supplying the number of steps, the traveled distance, the velocity and the acceleration of the lower limb, the average stride length and duration, the average amplitude of movement of the lower limb, as well as the format of the average stride in terms of the durations of each of its constituent phases.

16. Device for the measurement and calculation of dynamical parameters of pedestrian locomotion, according to claim 7 further comprising means of communication with an external unit, by a wired or wireless communication module.