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Upper body motion measurement system and upper body motion measurement method NEW

外国特許コード F200010125
整理番号 4397
掲載日 2020年5月18日
出願国 アメリカ合衆国
出願番号 201514668217
公報番号 9804189
出願日 平成27年3月25日(2015.3.25)
公報発行日 平成29年10月31日(2017.10.31)
優先権データ
  • 特願2014-064658 (2014.3.26) JP
発明の名称 (英語) Upper body motion measurement system and upper body motion measurement method NEW
発明の概要(英語) An upper body motion measurement system 1 has a plurality of inertia sensor units 2, each of which incorporating an angular velocity sensor 4 and an acceleration sensor 5. The plurality of the inertia sensor units 2 is attached to places that are different from each other on the upper body of a subject P. Based on the detection outputs of the angular velocity sensor 4 and the acceleration sensor 5, the attitude of each of the inertia sensor units 2 is estimated, and the acceleration thereof is further estimated. The angular acceleration of the upper body of the subject P is estimated based on the estimated accelerations of the plurality of the inertia sensor units 2.
従来技術、競合技術の概要(英語) BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a system and a method for estimating the change in the posture of the upper body of a person (subject).
Description of the Related Art
Hitherto, in order to grasp the walking state of a person, the posture of a predetermined part of a walking person, or a change or the like of the posture has generally been measured using an angular velocity sensor, such as a gyro sensor.
For example, Japanese Patent Application Laid-Open No. 2012-65723 (hereinafter referred to as Patent Document 1) describes a technique in which gyro sensors are attached to the waist and the thigh, the crus and the foot of each leg of a walker, and the joint angles of a hip joint, a knee joint, and an ankle joint are measured using the detection values of the gyro sensors.
In the meantime, according to various experiments and studies carried out by the inventors of the present application, the change in the posture of the upper body of a walking person, especially the change in the posture of the upper body in a pitch direction or a roll direction is markedly influenced by the motions of the legs of the walking person.
Further, especially the angular acceleration of the upper body is closely connected with the state of a floor reaction force acting on the walking person.
Therefore, observing the change in the posture of the upper body, including the angular acceleration, of the upper body of the walking person is highly necessary for grasping or assessing the walking state (e.g. the motional balance of right and left legs or the state of a leg motion recovered by rehabilitation) of a person.
In this case, angular velocity sensors, such as gyro sensors, could be attached to the upper body of a person, so that the change in the posture of the upper body could be observed based on the detection values of the angular velocities indicated by the angular velocity sensors. Further, in this case, as with the gyro sensor on the waist described in Patent Document 1, an angular velocity sensor could be attached to the upper body of a person through a fixing plate, such as a wide belt.
However, according to the technique in which an angular velocity sensor is attached to the upper body of a person through a fixing plate, such as a wide belt, as described above, the fixing plate is placed on a relatively large contact surface of the upper body of a person. This tends to cause the person discomfort or the feeling of an attached foreign object.
Further, in some cases, the discomfort, the feeling of an attached foreign object or the weight of the fixing plate inconveniently causes the walking form of a person to be different from his/her normal walking form without the fixing plate attached. This makes it impossible to properly assess the walking state of the person with high reliability.
To avoid the aforesaid inconvenience, the contact area occupied by the angular velocity sensor attached to the upper body of the person could be minimized.
This, however, would make it difficult to cause the attitude of the angular velocity sensor to accurately and stably follow the posture of the upper body of the person. Hence, the change in the attitude of the angular velocity sensor tends to deviate from the actual change in the posture of the upper body. As a result, it becomes difficult to observe the posture change of the upper body of the person with high reliability.
Further, if, for example, the angular acceleration of the upper body of a person is to be measured using an angular velocity sensor attached to the upper body, then it is necessary to carry out calculation for differentiating the detection values of the angular velocity obtained by the angular velocity sensor. Therefore, the measurement values of the angular velocity of the upper body are susceptible to the influence of noise components contained in the detection values of the angular velocity. This is inconveniently prone to result in deteriorated measurement accuracy of the angular acceleration of the upper body.
特許請求の範囲(英語) [claim1]
1. An upper body motion measurement system comprising:
at least one central processing unit comprising
a plurality of inertia sensor units, each of which includes a set of an angular velocity sensor that detects an angular velocity and an acceleration sensor that detects an acceleration and which are attached to places that are different from each other on an upper body of a subject;
a sensor unit attitude estimating unit configured to estimate an attitude of each of the inertia sensor units in a motion environment of the subject based on a detection value of an angular velocity and a detection value of an acceleration indicated by detection outputs of the angular velocity sensor and the acceleration sensor of each of the inertia sensor units attached to the upper body of the subject;
a sensor unit acceleration estimating unit configured to estimate an acceleration of each of the inertia sensor units observed in a global coordinate system set in the motion environment of the subject based on a detection value of an acceleration indicated by a detection output of the acceleration sensor of each of the inertia sensor units attached to the upper body of the subject, and the attitude of each of the inertia sensor units estimated by the sensor unit attitude estimating unit; and
an upper body angular acceleration estimating unit configured to estimate an angular acceleration of the upper body of the subject observed in the global coordinate system based on a set of accelerations estimated by the sensor unit acceleration estimating unit on each of the plurality of the inertia sensor units.

[claim2]
2. The upper body motion measurement system according to claim 1,
wherein the plurality of the inertia sensor units includes at least two inertia sensor units attached to the upper body with an interval provided in a vertical direction of the upper body along a trunk axis of the subject, and
the angular acceleration estimated by the upper body angular acceleration estimating unit includes at least one of the angular acceleration of the upper body in a roll direction of the subject and the angular acceleration in a pitch direction of the subject.

[claim3]
3. The upper body motion measurement system according to claim 2,
wherein an upper inertia sensor unit of the two inertia sensor units is attached to the upper body of the subject at a location on an upper side from a boundary between a thoracic vertebra and a lumbar vertebra of the subject, and a lower inertia sensor unit of the two inertia sensor units is attached to the upper body of the subject at a location on a lower side from the boundary between the thoracic vertebra and the lumbar vertebra of the subject.

[claim4]
4. The upper body motion measurement system according to claim 1,
wherein the acceleration of each of the inertia sensor units observed in the global coordinate system or the angular acceleration of the upper body of the subject observed in the global coordinate system is defined as a target state amount, and the sensor unit acceleration estimating unit or the upper body angular acceleration estimating unit is configured to carry out basic estimated value generation processing for generating a time series of estimated values of the target state amount in a walking motion and average waveform data generation processing for generating average waveform data of the target state amount in a gait for two steps in the walking motion in a case where the subject wearing the plurality of the inertia sensor units on his/her upper body performs the walking motion, and
the average waveform data generation processing is configured to transform in scale the waveform data, which is indicated by the time series of the estimated values of the target state amount generated by the basic estimated value generation processing for each of an n number (n: an integer of 2 or more) of two-step gaits included in the walking motion of the subject, in a direction of a time axis thereby to generate normalized waveform data obtained by normalizing a time width of a period of the two-step gait and further configured to generate average waveform data of an n number of pieces of the normalized waveform data for each of the n number of the two-step gaits as the average waveform data.

[claim5]
5. The upper body motion measurement system according to claim 4,
wherein processing for generating the normalized waveform data in the average waveform data generation processing is configured to generate the normalized waveform data such that a ratio between a time width of a one-step period of a right leg of the subject and a time width of a one-step period of a left leg of the subject in the normalized waveform data coincides with a ratio between an average value of an actual time width of the one-step period of the right leg in an n number of two-step gaits included in the walking motion of the subject and an average value of an actual time width of the one-step period of the left leg in the n number of two-step gaits.

[claim6]
6. The upper body motion measurement system according to claim 4,
wherein the sensor unit acceleration estimating unit or the upper body angular acceleration estimating unit, which carries out the average waveform data generation processing, is configured to further carry out offset component removal processing for removing an offset component from the average waveform data generated by the average waveform data generation processing, and the offset component removal processing is configured to remove the offset component such that a condition is satisfied, in which an average value in the period of the two-step gait of the value of the target state amount indicated by average waveform data after the offset component is removed becomes zero.

[claim7]
7. The upper body motion measurement system according to claim 4,
wherein the sensor unit acceleration estimating unit or the upper body angular acceleration estimating unit, which carries out the average waveform data generation processing, is configured to recognize a switching timing for each step in a walking motion of the subject based on a detection value of acceleration indicated by a detection output of an acceleration sensor of at least one inertia sensor unit among the plurality of the inertia sensor units or a change in acceleration estimated by the sensor unit acceleration estimating unit on at least the one inertia sensor unit.

[claim8]
8. The upper body motion measurement system according to claim 4,
wherein the sensor unit acceleration estimating unit is configured to generate the average waveform data related to the acceleration of each of the inertia sensor units,
the upper body angular acceleration estimating unit is configured to generate angular acceleration waveform data composed of a time series of an estimated value of the angular acceleration of the upper body of the subject in the period of the two-step gait by using an estimated value of the acceleration of each of the inertia sensor units indicated by the average waveform data generated by the sensor unit acceleration estimating unit related to each of the plurality of inertia sensor units,
an upper body angular velocity estimating unit that calculates an estimated value of the angular velocity of the upper body of the subject by integrating an estimated value of angular acceleration indicated by the angular acceleration waveform data generated by the upper body angular acceleration estimating unit is further provided, and
the upper body angular velocity estimating unit is configured to calculate an estimated value of an angular velocity of the upper body of the subject such that a condition is satisfied, in which an average value of an estimated value of the angular velocity of the upper body of the subject in the period of the two-step gait is zero.

[claim9]
9. The upper body motion measurement system according to claim 4,
wherein the upper body angular acceleration estimating unit is configured to generate the average waveform data related to the angular acceleration of the upper body of the subject,
an upper body angular velocity estimating unit that calculates an estimated value of the angular velocity of the upper body of the subject by integrating an estimated value of angular acceleration indicated by the average waveform data generated by the upper body angular acceleration estimating unit is further provided, and
the upper body angular velocity estimating unit is configured to calculate an estimated value of the angular velocity of the upper body of the subject such that a condition is satisfied, in which an average value of the estimated value of the angular velocity of the upper body of the subject in the period of the two-step gait is zero.

[claim10]
10. An upper body motion measurement method comprising:
a first step of acquiring a detection output of each of an angular velocity sensor and an acceleration sensor of each of a plurality of inertia sensor units in a state in which the plurality of the inertia sensor units, each of which has a set of the angular velocity sensor that detects an angular velocity and the acceleration sensor that detects an acceleration, is attached to places that are different from each other on an upper body of a subject;
a second step of estimating an attitude of each of the inertia sensor units in a motion environment of the subject based on a detection value of an angular velocity and a detection value of an acceleration indicated by detection outputs of the angular velocity sensor and the acceleration sensor of each of the inertia sensor units acquired in the first step;
a third step of estimating an acceleration of each of the inertia sensor units observed in a global coordinate system set in a travel environment of the subject based on a detection value of an acceleration indicated by a detection output of the acceleration sensor of each of the inertia sensor units acquired in the first step, and the attitude of each of the inertia sensor units estimated in the second step on each of the inertia sensor units; and
a fourth step of estimating an angular acceleration of the upper body of the subject observed in the global coordinate system based on a set of accelerations estimated in the third step on each of the plurality of the inertia sensor units.

[claim11]
11. The upper body motion measurement system according to claim 1,
wherein the angular velocity detected by the angular velocity sensor of each of the inertial sensor units is a three-dimensional space angular velocity vector, and
wherein the acceleration detected by the acceleration sensor of each of the inertial sensor units is a three-dimensional space acceleration vector.
  • 発明者/出願人(英語)
  • TAKENAKA Toru
  • IKEUCHI Yasushi
  • NAGATA Yosuke
  • OHATA Koji
  • HONDA MOTOR
  • KYOTO UNIVERSITY
国際特許分類(IPC)
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