Apparatus of chasing posture of moving material object, method of chasing posture of moving material object, apparatus of chasing posture of toothbrush and method of chasing posture of toothbrush using the samelectric toothbrush and method for controlling thereof

A method of tracking an posture of a moving object in a three-dimensional space having a z-axis facing a reference surface of the moving object, an x-axis perpendicular to the z-axis in a virtual vertical plane including the z-axis, and a y-axis perpendicular to the x-axis in a virtual horizontal plane including the x-axis, the method comprising:

• detecting which direction of up, down, left and right the reference surface is facing with the x-axis as an axis of rotation by using a roll angle of the reference surface that is amended according to a variation of a pitch angle of the reference surface from gravity;
• detecting how far an x-axis direction of the moving object is relatively deviated from a magnetic north direction;
• sorting output data of a terrestrial magnetism sensor;
• and
• determining the posture of the moving object based on how far the x-axis of the moving object is deviated and which direction of up, down, left and right the reference surface is facing in response to the detected reference surface direction detection signal and the detected x-axis deviation detection signal.

An apparatus for tracking an posture of a toothbrush in a three-dimensional oral cavity having a direction toothbrush bristles are facing, a toothbrush handle length direction perpendicular to the direction the toothbrush bristles are facing in a virtual vertical plane including an axis of the direction the toothbrush bristles are facing, and a toothbrush bristle shaking direction perpendicular to the toothbrush handle length direction in a virtual horizontal plane including the toothbrush handle length direction, the apparatus comprising:

• a triaxial accelerometer configured to detect which direction of up, down, left and right in an oral cavity the toothbrush bristles are facing with the toothbrush handle length direction as an axis of rotation by using a roll angle of the reference surface that is amended according to a variation of a pitch angle of the reference surface from gravity;
• a terrestrial magnetism sensor configured to detect how far the toothbrush handle length direction is relatively deviated in the oral cavity from a magnetic north direction;
• a sorter configured to sort output data of a terrestrial magnetism sensor;
• and
• a determination unit configured to determine which tooth portion is currently being brushed by the toothbrush bristles by determining how far a toothbrush handle of the toothbrush is relatively deviated from the magnetic north direction and which direction of up, down, left and right the toothbrush bristles are facing in response to detection signals of the triaxial accelerometer and the terrestrial magnetism sensor.

A method of tracking an posture of a toothbrush in a three-dimensional oral cavity having a direction toothbrush bristles are facing, a toothbrush handle length direction perpendicular to the direction the toothbrush bristles are facing in a virtual vertical plane including an axis of the direction the toothbrush bristles are facing, and a toothbrush bristle shaking direction perpendicular to the toothbrush handle length direction in a virtual horizontal plane including the toothbrush handle length direction, the method comprising:

• detecting which direction of up, down, left and right in an oral cavity the toothbrush bristles are facing with the toothbrush handle length direction as an axis of rotation, using a triaxial accelerometer by using a roll angle of the reference surface that is amended according to a variation of a pitch angle of the reference surface from gravity;
• detecting how far the toothbrush handle length direction is relatively deviated in the oral cavity from a magnetic north direction, using a terrestrial magnetism sensor;
• sorting output data of a terrestrial magnetism sensor;
• and
• determining which tooth portion is currently being brushed by the toothbrush bristles by determining how far a toothbrush handle of the toothbrush is relatively deviated from the magnetic north direction and which direction of up, down, left and right the toothbrush bristles are facing in response to detection signals of the triaxial accelerometer and the terrestrial magnetism sensor.