Sourceless orientation sensor

A method of measuring the orientation of an object, including the steps of:

• a) providing a sourceless orientation sensor comprising:
• i) two-axis magnetic sensing means for measuring the Earth's magnetic field,
• ii) measuring means for measuring elevation or roll angle of said object with respect to a fixed reference three-dimensional coordinate frame;
• and
• iii) a computer interconnected with said sensing means and measuring means;
• b) programming said computer with first data from an initial calibration procedure of measurements of the constant intensity of the Earth's magnetic field;
• c) feeding said computer second data from said sensing means concerning two axes of the Earth's magnetic field;
• d) calculating, in said computer, a third axis of the Earth's magnetic field;
• e) feeding said computer third data from said measuring means concerning elevation or roll angle of said object in a fixed reference three-dimensional coordinate frame;
• f) calculating orientation of said object in terms of azimuth, elevation and roll relative to a fixed reference three-dimensional coordinate frame.

A sourceless orientation sensor for determining orientation of an object, comprising:

• a) two-axis magnetic sensing means for measuring direction and strength of the Earth's magnetic field;
• b) accelerometer means for measuring acceleration of the Earth's gravity force;
• c) measuring means for measuring elevation and azimuth angle velocities of said object with respect to a sensor frame;
• and
• d) computer means for controlling taking of said measurements and for converting said measurements into azimuth, elevation and roll angles of said object with respect to a fixed reference three-dimensional coordinate frame.

A method of measuring the orientation of an object, including the steps of:

• a) providing a sourceless orientation sensor comprising:
• i) two-axis magnetic sensing means for measuring the Earth's magnetic field;
• ii) accelerometer means for measuring acceleration of the Earth's gravity force;
• iii) measuring means for measuring elevation and azimuth angle velocities of said object in a sensor frame;
• and
• iv) a computer interconnected with said sensing means and measuring means;
• b) programming said computer with first data from an initial calibration procedure of measurements of the constant intensity of the Earth's magnetic field;
• c) feeding said computer second data from said sensing means concerning two axes of the Earth's magnetic field;
• d) calculating, in said computer, a third axis of the Earth's magnetic field;
• e) feeding said computer third data from said accelerometer means concerning acceleration of the Earth's gravity force;
• f) said computer converting said angular velocity measurements into elevation and azimuth angles of said object in a fixed reference three-dimensional coordinate frame;
• g) said computer further converting said second data from said sensing means into roll angle of said object with respect to a fixed reference three-dimensional coordinate frame;
• h) said computer outputting azimuth, elevation and roll angles with respect to a fixed reference three-dimensional coordinate frame.

A method of measuring the orientation of an object, comprising:

• a) providing a sourceless orientation sensor comprising:
• i) two-axis magnetic sensing means for measuring Earth's magnetic field;
• ii) accelerometer means for measuring acceleration of Earth's gravity force;
• iii) measuring means for measuring elevation velocity of said object in a sensor frame;
• iv) a computer interconnected with said sensing means and said measuring means;
• b) programming said computer with first data from an initial calibration procedure of measurements of constant intensity of the Earth's magnetic field;
• c) feeding said computer with second data from said magnetic sensing means concerning two axes of Earth's magnetic field;
• d) calculating, in said computer, a third axis of the Earth's magnetic field;
• e) feeding said computer third data from said accelerometer means concerning acceleration of Earth's gravity force;
• f) said computer converting said elevation velocity and a last determined azimuth velocity into elevation and azimuth angle estimates of said object relative to a fixed reference three-dimensional coordinate frame;
• g) said computer further converting said signals from said magnetic sensing means into roll angle estimates of said object relative to said fixed reference three-dimensional coordinate frame;
• h) said computer further using said signals from said magnetic sensing means to find a different azimuth angle, comparing this azimuth angle to an azimuth angle estimate and finding a more accurate azimuth angle velocity estimate;
• i) said computer repeating steps f-h until a difference between two consecutively determined azimuth angles is less than a preprogrammed level;
• j) said computer outputting to a host computer said azimuth, elevation and roll angles of said object relative to said fixed reference three-dimensional coordinate frame.