Apparatus and method for measuring velocity of moving object in a navigation system

A navigation apparatus for measuring a velocity of a moving object, comprising:

• an acceleration sensor configured to measure an acceleration of a moving object and output an acceleration measurement value;
• an altimeter configured to measure an altitude of the moving object and output an altitude measurement value;
• and
• a calculation part configured to:
• determine a sign of an inclination angle of an inclined surface on which the moving object travels using the altitude measurement value,
• obtain a gravity component included in the acceleration measurement value,
• calculate a pure movement acceleration of the moving object by removing the gravity component from the acceleration measurement value, and
• calculate the velocity of the moving object by using the pure movement acceleration,
• wherein the altimeter measures the altitude of the moving object for a predetermined time period, and outputs the altitude measurement value, and
• wherein the calculation part is further configured to determine the sign of the inclination angle of the inclined surface by using the altitude measurement value for the predetermined time period.