MOTION DETERMINATION APPARATUS

• US 20120065524A1
• Filed: 06/02/2010
• Published: 03/15/2012
• Est. Priority Date: 06/05/2009
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Morren, Geert Guy Georges, Duric, Haris, Aarts, Ronaldus Maria, Jin, Anmin, Jin, Bin
• Granted Patent: US 9,510,775 B2
• Time in Patent Office: Days
• US Class Current: 600/484
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/1102 Ballistocardiography
• CPC Class Codes: A61B 5/1135 by monitoring thoracic expansion

Abstract

The invention relates to a motion determination apparatus for determining motion of a moving object, wherein the motion determination apparatus (1) comprises a multi-axial accelerometer (2) for being positioned at the moving object (4), wherein the multi-axial accelerometer (2) is adapted to generate accelerometer signals indicative of the acceleration along different spatial axes. The motion determination apparatus further comprises a motion signal generation unit (3) for generating a motion signal indicative of the motion of the object (4) by combining the accelerometer signals of different spatial axes. The combination of the accelerometer signals of different spatial axes yields a motion signal having a large signal-to-noise ratio, even if an axis is located close to a rotational axis of the movement.

Claims

1. A motion determination apparatus for determining motion of a moving object, wherein the motion determination apparatus comprises:

a multi-axial accelerometer for being positioned at the moving object, wherein the multi-axial accelerometer is adapted to generate accelerometer signals indicative of the acceleration along different spatial axes,

a motion signal generation unit for generating a motion signal indicative of the motion of the object by combining the accelerometer signals of different spatial axes.

2. The motion determination apparatus as defined in claim 1, wherein the multi-axial accelerometer is adapted to be positioned at a body of a person, wherein the motion signal generation unit is adapted to generate a motion signal indicative of at least one of respiration and heart activity of the person.

3. The motion determination apparatus as defined in claim 2, wherein the motion determination apparatus further comprises at least one of a breathing rate determination unit for determining a breathing rate and a heart rate determination unit for determining a heart rate depending on the generated motion signal.

4. The motion determination apparatus as defined in claim 1, wherein the motion determination apparatus further comprises a filtering unit for filtering the accelerometer signals such that frequencies corresponding to possible frequencies of the motion to be determined pass the filtering unit.

5. The motion determination apparatus as defined in claim 1, wherein the motion signal generation unit is adapted to repeatedly generate the motion signal based on accelerometer signals generated in a temporally preceding time frame.

6. The motion determination apparatus as defined in claim 1, wherein the motion signal generation unit is adapted to combine the accelerometer signals such that the accelerometer signal having the largest acceleration change contributes mostly to the motion signal.

7. The motion determination apparatus as defined in claim 1, wherein the motion signal generation unit is adapted to linearly combine the accelerometer signals of different spatial axes, wherein the accelerometer signals are weighted such that the accelerometer signal having the largest acceleration change has the largest weight.

8. The motion determination apparatus as defined in claim 7, wherein the motion signal generation unit is adapted to determine the weight of an accelerometer signal depending on a correlation of the respective accelerometer signal with the accelerometer signal having the largest acceleration change, wherein the weight of the respective accelerometer signal is the sign of the correlation.

9. The motion determination apparatus as defined in claim 1, wherein the motion signal generation unit is adapted to apply a principal component analysis on the accelerometer signals of the different spatial axes and to determine a motion component from principal components resulting from the application of the independent component analysis, which is indicative of the motion to be determined, as the motion signal.

10. The motion determination apparatus as defined in claim 1, wherein the motion signal generation unit is adapted to determine for each spatial axis of the accelerometer a maximized projection signal of the acceleration change and to generate the motion signal by combining the maximized projection signals, wherein the motion signal generation unit is adapted to determine the maximized projection signal of a spatial axis of the accelerometer by projecting a movement of a gravity vector relative to the spatial axes of the accelerometer on a subspace defined by the nominal gravity vector and the respective spatial axis of the accelerometer and by transforming the respective axis within the subspace such that a projection of the projected movement of the gravity vector, which has been projected into the subspace, on the transformed respective axis is maximized.

11. The motion determination apparatus as defined in claim 10, wherein the motion signal generation unit is adapted to generate the motion signal by determining a vector magnitude of the maximized projection signals and by combining the determined vector magnitude with the sign of at least one of the maximized projection signals.

12. The motion determination apparatus as defined in claim 10, wherein motion signal generation unit is adapted to apply a principal component analysis on the maximized projection signals, wherein the resulting first principal component is the generated motion signal.

13. The motion determination apparatus as defined in claim 1, wherein motion signal generation unit is adapted to apply an independent component analysis on the accelerometer signals of the different spatial axes and to determine a motion component from the independent components resulting from the application of the independent component analysis, which is indicative of the motion to be determined, as the motion signal.

15. A computer program for determining motion of a moving object, wherein the computer program comprises program code means for causing a motion determination apparatus as defined in claim 1, when the computer program is run on a computer controlling the motion determination apparatus.

14. A motion determination method for determining motion of a moving object, wherein the motion determination method comprises following steps:

generating accelerometer signals indicative of the acceleration along different spatial axes by a multi-axial accelerometer being positioned at the moving object,

generating a motion signal indicative of the motion of the object by combining the accelerometer signals of different spatial axes by a motion signal generation unit.