Method of motion tracking

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.