Method and device for determining a person's motions

• US 7,661,200 B2
• Filed: 03/30/2005
• Issued: 02/16/2010
• Est. Priority Date: 03/30/2004
• Status: Active Grant

• Current Assignee: Commissariat a L'Energie Atomique (French Alternative Energies and Atomic Energy Commission)
• Original Assignee: Commissariat a L'Energie Atomique (French Alternative Energies and Atomic Energy Commission)
• Inventors: Bonnet, Stephane, Guillemaud, Regis
• Primary Examiner(s): Bennett; G. Bradley
• Assistant Examiner(s): Courson; Tania C
• Application Number:
  US10/592,799
• Publication Number:
  US 20070186429A1
• Time in Patent Office: 1,784 Days
• Field of Search: 335/12, 33/1.PT, 33/1.N, 33281-282, 332/85
• US Class Current: 33/512
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/1116 Determining posture transitions

Abstract

A sensor worn by a person measures movements of the person. Movements of orientation are not expressed by rotations leading from a stationary reference point to a reference point associated with the sensor, but by angles separating axes or planes of the stationary reference point and axes associated with the wearer, thereby making it possible to better identify his/her movements and his/her activity. The sensor can be applied to the monitoring of patients.

Claims

1. A method for determining movement of a person, comprising:

preliminarily calibrating a sensor that is installed on the person by recording a preliminary orientation of the sensor while the person is at a predetermined orientation with respect to a stationary reference;

performing a repeated computation of an orientation of the sensor with respect to the stationary reference, expressed as a combination of rotations from the stationary reference, from signals of the sensor; and

correcting the combination of rotations so as to express rotations of the sensor bound to the person, which includes a vertical axis, a front-back horizontal axis and a left-right horizontal axis, as another combination of rotations of the person that include a side inclination of the person, a front-back inclination of the person and an azimuth rotation of the person.

2. The method according to claim 1, wherein the sensor includes accelerometers and magnetometers.

3. The method according to claim 1, wherein the sensor includes gyrometers.

4. The method according to claim 1, wherein angles of orientation of the sensor are Euler angles.

5. The method according to claim 1, wherein angles of orientation of the sensor are expressed by quaternions.

6. The method according to claim 1, wherein

the preliminary calibrating includes storing an orientation of the person with respect to the stationary reference point and storing an orientation of the sensor with respect to the stationary reference point while the person is at the predetermined orientation, and

the correcting includes converting the combination of rotations of the sensor into the another combination of rotations of the person that include the side inclination of the person, the front-back inclination of the person and the azimuth of the person based the orientation of the person with respect to the stationary reference point and the orientation of the sensor with respect to the stationary reference point.

7. A device configured to determine a movement of a person, comprising:

a memory; and

a processing apparatus configured to

preliminarily calibrate a sensor that is installed on the person by causing a preliminary orientation of the sensor while the person is at a predetermined orientation with respect to a stationary reference to be recorded in the memory,

perform a repeated computation of an orientation of the sensor with respect to the stationary reference, expressed as a combination of rotations from the stationary reference, from signals of the sensor, and

correct the combination of rotations so as to express rotations of the sensor bound to the person, which includes a vertical axis, a front-back horizontal axis and a left-right horizontal axis, as another combination of rotations that include a side inclination of the person, a front-back inclination of the person and an azimuth rotation of the person.