Method for estimating attachment posture of inertial sensor

Patent metadata

Field	Value
Publication number	US-11320450-B2
Application number	US-202016810869-A
Country	US
Kind code	B2
Filing date	Mar 6, 2020
Priority date	Mar 11, 2019
Publication date	May 3, 2022
Grant date	May 3, 2022

Abstract

An acceleration vector is detected in a kept-still state of a measurement target portion such as thighs of a target person to which an inertial sensor is attached, and further, another acceleration vector is detected in a state in which the target person is allowed to carry out exercise such that a posture of the measurement target portion is caused to change in a direction around a Yb axis with a Yb-axis direction of the measurement target portion maintained in a direction that perpendicularly intersects a vertical direction, direction in a sensor coordinate system the Yb-axis direction of the measurement target portion corresponds to is identified on the basis of a cross product vector of the acceleration vector and another acceleration vector.

First claim

What is claimed is:

1. A method for estimating an attachment posture of an inertial sensor, for estimating a relative posture relationship between a measurement target portion of a target person by a measurement processing device and an inertial sensor that is attached to the measurement target portion and includes an acceleration sensor capable of communicating with the measurement processing device and detecting accelerations in the respective coordinate axes in a sensor coordinate system, which is a three-dimensional coordinate system set in advance for the inertial sensor, the method for estimating an attachment posture of an inertial sensor comprising:
a first process of detecting, with the acceleration sensor, a first acceleration vector that is an acceleration vector including a set of accelerations in three coordinate axis directions in the sensor coordinate system in a state in which the measurement target portion is kept still, and maintaining a first direction which is a predetermined direction set in advance with respect to the measurement target portion in a direction that perpendicularly intersects a vertical direction;
a second process of allowing the target person to carry out exercise of causing a posture of the measurement target portion to change in a direction around an axis in the first direction with the first direction of the measurement target portion maintained in a direction that is the same as the direction in the first process;
a third process of detecting, with the acceleration sensor, a second acceleration vector that is an acceleration vector including a set of accelerations in the three coordinate axis directions in the sensor coordinate system and has a direction that is different from a direction of the first acceleration vector, at one or more sampling times in the second process;
a fourth process of identifying first posture data by the measurement processing device that indicates which direction in the sensor coordinate system the first direction of the measurement target portion corresponds to when seen in the sensor coordinate system, on the basis of one or more cross product vectors calculated in a cross product operation between each of one or more second acceleration vectors detected in the third process and the first acceleration vector detected in the first process;
a fifth process of allowing the target person to keep the measurement target portion still such that a second direction that is set in advance with respect to the measurement target portion as a direction that is different from the first direction is maintained in a vertical direction;
a sixth process of detecting, with the acceleration sensor, a set of accelerations of the three coordinate axis directions in the sensor coordinate system at one or more sampling times in the fifth process;
a seventh process of identifying second posture data indicating which direction in the sensor coordinate system the second direction of the measurement target portion corresponds to, on the basis of one or more sets of accelerations detected in the fifth process; and
an eighth process of identifying third posture data indicating which direction a third direction that perpendicularly intersects the first direction and the second direction corresponds to when seen in the sensor coordinate system on the basis of the first posture data identified in the fourth process and the second posture data identified in the seventh process,
wherein in the eighth process, a vector obtained through a cross product operation of a vector in the first direction indicated by the first posture data and a vector in the second direction indicated by the second posture data is identified as the third posture data.

2. The method for estimating an attachment posture of an inertial sensor according to claim 1 ,
wherein the exercise that the target person is allowed to carry out in the second process is exercise of sequentially causing the posture of the measurement target portion to change in one of a forward direction and a reverse direction that is a direction around the axis in the first direction and causing the posture of the measurement target portion to change in the other direction, and
the second acceleration vector detected in the third process includes at least an acceleration vector at a timing of switching of a direction of a change in posture of the measurement target portion around the axis in the first direction.

3. The method for estimating an attachment posture of an inertial sensor according to claim 2 ,
wherein the measurement target portion is lower legs or thighs of legs of the target person,
the first direction is a left-right direction of the target person, and
the exercise that the target person is allowed to carry out in the second process is exercise that includes at least bending and stretching the legs such that a posture of the thighs or the lower legs of the legs is caused to change in a pitch direction.

4. The method for estimating an attachment posture of an inertial sensor according to claim 2 ,
wherein the measurement target portion is an upper body of the target person,
the first direction is a left-right direction of the target person, and
the exerciser that the target person is allowed to carry out in the second process is exercise that includes at least inclining the upper body of the target person in a pitch direction.

5. The method for estimating an attachment posture of an inertial sensor according to claim 1 ,
wherein the measurement target portion is lower legs or thighs of legs of the target person,
the first direction is a left-right direction of the target person, and
the exercise that the target person is allowed to carry out in the second process is exercise that includes at least bending and stretching the legs such that a posture of the thighs or the lower legs of the legs is caused to change in a pitch direction.

6. The method for estimating an attachment posture of an inertial sensor according to claim 1 ,
wherein the measurement target portion is an upper body of the target person,
the first direction is a left-right direction of the target person, and
the exerciser that the target person is allowed to carry out in the second process is exercise that includes at least inclining the upper body of the target person in a pitch direction.

7. The method for estimating an attachment posture of an inertial sensor according to claim 1 ,
wherein the measurement target portion is a lower leg or a thigh of a leg or an upper body of the target person, and
the second direction is a direction that is able to be directed in the vertical direction in a state in which the target person is standing up in an upright posture or in a state in which a body of the target person is kept still in contact with an object with a specific shape.

Assignees

• Honda Motor Co Ltd

Inventors

• Ikeuchi Yasushi

Classifications

• A61B5/11

  Measuring movement of the entire body or parts thereof, e.g. head or hand tremor or mobility of a limb {(A61B5/1038 takes precedence; motion detection to correct for motion artifacts in physiological signals A61B5/721)} · CPC title

• G01P15/02 Primary

  by making use of inertia forces {using solid seismic masses}(G01P15/14 takes precedence) · CPC title

• A61B5/1122 Primary

  of movement trajectories · CPC title

• A61B5/1126 Primary

  using a particular sensing technique · CPC title

• A61B5/1116

  Determining posture transitions · CPC title