Method of motion tracking

Patent metadata

Field	Value
Publication number	US-9759539-B2
Application number	US-201214119960-A
Country	US
Kind code	B2
Filing date	Feb 15, 2012
Priority date	May 25, 2011
Publication date	Sep 12, 2017
Grant date	Sep 12, 2017

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.

First claim

The invention claimed is:

1. A method of tracking a motion of a model comprising a joint, body parts that rotate with respect to the joint, and inertial sensors attached to each of the body parts to measure a rotational motion of each of the body parts, the method comprising:
attaching the inertial sensors to each of the body parts in different orientations with respect to one or more of each of the body parts and ground, wherein the inertial sensors are attached to each of the body parts without matching a direction of the body part coordinate system with a corresponding direction of the sensor coordinate system of each of the inertial sensors;
tracking motion of the body parts using the inertial sensors;
capturing a motion of the body parts using a joint variable and a rotational matrix of the body part coordinate system;
outputting the calculated joint variable as a captured motion of the body parts;
a sensor posture measurement operation of obtaining the rotational matrix of the sensor coordinate system fixed to each of the inertial sensors with respect to an inertial coordinate system fixed to the ground using a signal measured by the inertial sensors;
a rotational matrix conversion operation of obtaining the rotational matrix of the sensor coordinate systems with respect to the body part coordinate system fixed to each of the body parts, 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 using a rotational matrix of the sensor coordinate systems calculated in the rotational matrix conversion operation;
using a rotational matrix value of the sensor coordinate system obtained in the obtaining of the rotation matrix of the sensor coordinate system fixed to each of the inertial sensors with respect to the inertial coordinate system fixed to the ground, and a signal measured by the inertial sensor attached to each of the body parts, as each of the body parts performs three or more motions; and
a joint variable calculation operation of calculating a joint variable with respect to each body part, using a rotational matrix of the body part coordinate system calculated in the body part posture calculation operation,
wherein the obtaining of the rotational matrix of the sensor coordinate systems with respect to the body part coordinate system fixed to each of the body parts comprises using a signal measured by the inertial sensor attached to each of the body parts as each of the body parts performs three or more motions,
wherein the calculating of the joint variable further comprises transforming motion data, measured by the inertial sensor with respect to the sensor coordinate system fixed to each of the inertial sensors, using the rotational matrix of the body part coordinate system to produce the calculated joint variable, and
wherein the model is a human body comprising 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, a waist joint between the trunk and the pelvis comprising a joint variable of three degrees of freedom, a shoulder joint between the upper arm and the trunk comprising a joint variable of three degrees of freedom, and an elbow joint between the lower arm and the upper arm comprising a joint variable of three degrees of freedom.

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

3. The method of claim 1 , wherein the inertial sensor is configured to wirelessly transmit a measured signal.

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

Assignees

• Kim Jinwook
• Jung Yujin
• Kang Donghoon
• Korea Inst Sci & Tech

Inventors

• Kim Jinwook
• Jung Yujin
• Kang Donghoon

Classifications

• G06F3/011

  Arrangements for interaction with the human body, e.g. for user immersion in virtual reality (blind teaching G09B21/00) · CPC title

• G01B5/004 Primary

  for measuring coordinates of points · CPC title

• A61B5/1114 Primary

  Tracking parts of the body · CPC title

• A61B5/6825

  Hand · CPC title

• A61B5/6824

  Arm or wrist · CPC title