POWER MEASUREMENT METHOD AND APPARATUS

• US 20110178760A1
• Filed: 09/17/2009
• Published: 07/21/2011
• Est. Priority Date: 09/23/2008
• Status: Active Grant

• Current Assignee: Lifeline Systems Company (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Schlumbohm, Stephan, Zijlstra, Wiebren, Baldus, Heribert
• Granted Patent: US 9,730,617 B2
• Time in Patent Office: Days
• US Class Current: 702/141
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/1117 Fall detection
• CPC Class Codes: A61B 5/6831 Straps, bands or harnesses
• CPC Class Codes: A63B 2220/40 Acceleration
• CPC Class Codes: A63B 2220/50 Force related parameters

Abstract

There is provided an apparatus for estimating the power used by a user in performing the vertical component of a movement, the apparatus comprising an accelerometer for attachment to a user and for measuring the acceleration experienced by the user; the apparatus further comprising a processor configured to receive the measurements of the acceleration from the accelerometer attached to the user; estimate the vertical accelerations from the received measurements; and estimate the power used from the vertical accelerations.

Claims

1. An apparatus for estimating power used by a user in performing a vertical component of a movement, the apparatus comprising:

an accelerometer for attachment to a user and for measuring acceleration experienced by the user;

the apparatus further comprising;

a processor configured to;

receive the measurements of the acceleration from the accelerometer attached to the user;

estimate vertical accelerations from the received measurements; and

estimate the power used from the vertical accelerations.

2. An apparatus as claimed in claim 1, wherein the processor is configured to estimate the power used from the vertical accelerations by evaluating:

Power(t)=m*(acc_vert(t)+g)*∫

(acc_vert(t))dt

where m is the mass of the user, acc_vert(t) is the vertical acceleration at a time t, and g is acceleration due to gravity.

3. An apparatus as claimed in claim 1, wherein the processor is configured to estimate the power used from the vertical accelerations by:

estimating the reaction force from the ground, the estimate being determined from the estimate of the vertical acceleration;

estimating the vertical velocity by integrating the estimates of the vertical acceleration over the time taken to perform the movement; and

estimating the power used from the estimate of the ground reaction force and the estimate of the vertical velocity.

4. An apparatus as claimed in claim 3, wherein the processor is configured to estimate the power used by multiplying the estimate of the ground reaction force and the estimate of the vertical velocity.

5. An apparatus as claimed in claim 3, wherein the processor is configured to estimate the reaction force from the ground from:

F_gr(t)=(acc_vert(t)+g)*m

where m is the mass of the user and acc_vert(t) is the vertical acceleration at a time t.

6. An apparatus as claimed in claim 3, wherein the processor is configured to estimate the vertical velocity from

vel_vert(t)=∫

(acc_vert(t))dt

where acc_vert(t) is the vertical acceleration at a time t.

7. An apparatus as claimed in claim 1, wherein the processor is configured to estimate the vertical accelerations from the received measurements by:

estimating the orientation of the accelerometer from the received measurements; and

identifying the vertical accelerations in the received measurements using the estimated orientation.

8. An apparatus as claimed in claim 1, wherein the apparatus further comprises a gyroscope and/or magnetometer associated with the accelerometer, and wherein the processor is configured to estimate the vertical accelerations from the received measurements by:

estimating the orientation of the accelerometer from measurements received from the gyroscope and/or magnetometer; and

identifying the vertical accelerations in the received measurements using the estimated orientation.

9. An apparatus as claimed in claim 1, wherein the processor and accelerometer are integrated into a single unit for attachment to the user.

10. An apparatus as claimed in claim 1, wherein the apparatus comprises a plurality of accelerometers for attachment to respective parts of the body of the user.

11. An apparatus as claimed in claim 10, wherein the processor is configured to receive the measurements of the acceleration from the plurality of accelerometers attached to the user and to determine an estimate of the acceleration of the centre of mass of the user from the measurements.

12. An apparatus as claimed in claim 11, wherein the estimate of the acceleration of the centre of mass of the user is determined from a weighted average of the measurements from the plurality of accelerometers.

13. An apparatus as claimed in claim 1, wherein the apparatus is for estimating the power used by a user in performing a sit-to-stand transfer.

14. A method for estimating power used by a user in performing a vertical component of a movement, the method comprising:

obtaining measurements of vertical acceleration experienced by the user in performing the movement from an accelerometer attached to the user; and

determining an estimate of the power used from the measurements of the vertical acceleration.

15. A computer program product, comprising computer program code that, when executed on a computer or processor associated with an accelerometer attached to a user estimates power used by a user in performing a vertical component of a movement by:

receiving measurements from the accelerometer;

determining vertical acceleration experienced by the user in performing the movement from the received measurements; and

determining an estimate of the power used from the measurements of the vertical acceleration.