# US 2014/0156218 A1 · Method of motion tracking

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- Number: US 2014/0156218 A1
- Document ID: US20140156218A1
- Status: Published application
- Kind: A1
- Application number: 14/119,960
- Filed: 2012-02-15
- Published: 2014-06-05
- Earliest claimed: 2011-05-25
- Assignees: Korea Institute of Science and Technology
- Applicants: Korea Institute of Science and Technology
- Inventors: Jinwook Kim; Yujin Jung; Donghoon Kang
- Web page: https://patentgrep.com/patent/US20140156218A1

## CPC

- G01B 5/004: for measuring coordinates of points
- A61B 5/1114: {Tracking parts of the body}
- G06F 3/011: {Arrangements for interaction with the human body, e.g. for user immersion in virtual reality (blind teaching G09B21/00)}
- A61B 5/6822: {Neck}
- A61B 5/6823: {Trunk, e.g., chest, back, abdomen, hip}
- A61B 5/6824: {Arm or wrist}
- A61B 5/6825: {Hand}
- A61B 5/6828: {Leg}
- A61B 5/6829: {Foot or ankle}
- A61B 5/6831: {Straps, bands or harnesses}
- A61B 2503/10: Athletes
- A61B 2505/09: Rehabilitation or training
- G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)

## Abstract

A motion of a model including a joint, at least one body part that rotates with respect to the joint, and a plurality of inertial sensors attached to each body part and measuring a rotational motion of the body part is tracked by obtaining a rotational matrix of a sensor coordinate system fixed to each of the inertial sensors with respect to an inertial coordinate system fixed to ground, by using a signal measured by the inertial sensor attached to each body part; obtaining a rotational matrix of the sensor coordinate systems with respect to a body part coordinate system fixed to each body part, by using an obtained rotational matrix value of the sensor coordinate system; obtaining a rotational matrix of each body part coordinate system with respect to the inertial coordinate system, by using a calculated rotational matrix of the sensor coordinate systems; and calculating a joint variable with respect to each body part, by using a calculated rotational matrix of the body part coordinate system.

## Claims

### Claim 1

A method of tracking a motion of a model including a joint, at least one body part that rotates with respect to the joint, and a plurality of inertial sensors attached to each body part and measuring a rotational motion of the body part, the method comprising:
a sensor posture measurement operation of obtaining a rotational matrix of a sensor coordinate system fixed to each of the plurality of inertial sensors with respect to an inertial coordinate system fixed to ground, by using a signal measured by the inertial sensor attached to each body part;
a rotational matrix conversion operation of obtaining a rotational matrix of the sensor coordinate systems with respect to a body part coordinate system fixed to each body part, by using a rotational matrix value of the sensor coordinate system obtained in the sensor posture measurement operation;
a body part posture calculation operation of obtaining a rotational matrix of each body part coordinate system with respect to the inertial coordinate system, by using a rotational matrix of the sensor coordinate systems calculated in the rotational matrix conversion operation; and
a joint variable calculation operation of calculating a joint variable with respect to each body part, by using a rotational matrix of the body part coordinate system calculated in the body part posture calculation operation.

### Claim 2 (depends on 1)

The method of claim 1, wherein the model is a human body including a trunk, a pelvis coupled to the trunk through a joint, an upper arm coupled to the trunk through a joint, and a lower arm coupled to the upper arm through a joint.

### Claim 3 (depends on 1)

The method of claim 1, wherein the inertial sensor is a sensor capable of measuring translational inertia, rotational inertia, and terrestrial magnetism.

### Claim 4 (depends on 1)

The method of claim 1, wherein the inertial sensor transmits a measured signal to the outside wirelessly.

### Claim 5 (depends on 1)

The method of claim 1, wherein the inertial sensor is manufactured according to micro-electromechanical systems (MEMS) technology to be small and light.