Instrument and method for measuring three-dimensional motion
AssigneeJapan Science and Technology Agency
InventorsKenichi Arai, Shin Yabukami, Hiroyasu Kanetaka
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Abstract
An instrument (10) for measuring three-dimensional motion in a living body comprises a plurality of magnetism generators (12i) fixed to one of at least two objects (44, 46) moving relatively in the living body, a plurality of magnetic field sensors (14j) fixed to the other object in order to perform noncontact detection of the magnetic field of each magnetism generator (12i), and a signal processing means (26) for calculating relative position and direction between each magnetism generator (12i) and each magnetic field sensor (14j) according to a magnetic field detected by each magnetic field sensor (14j). The number of magnetism generators (12i) and magnetic field sensors (14j) is at least five, respectively.
Claims14
An apparatus for measuring three-dimensional movement, comprising:
- a plurality of magnetic generators mounted on one of at least two relatively movable objects;
- a plurality of magnetic field sensors mounted on another object, for detecting magnetic fields of said magnetic generators out of contact therewith;
- signal processing means for calculating relative positions and directions between said magnetic generators and said magnetic field sensors from the magnetic fields detected by said magnetic field sensors;
- and
- a plurality of non-contact calibrating coils;
- wherein said magnetic generators and said magnetic field sensors are paired in at least five combinations;
- each of said calibrating coils is paired in a total of at least five combinations;
- and
- calibrating magnetic fields generated by said calibrating coils are detected by said magnetic generators and said magnetic field sensors to measure initial positions and initial directions of said magnetic generators and said magnetic field sensors.
A method of measuring three-dimensional relative movement of at least two objects, comprising the steps of:
- mounting a plurality of magnetic generators on one of said two objects, mounting a plurality of magnetic field sensors on another object, with said magnetic generators and said magnetic field sensors being paired in at least five combinations;
- placing a plurality of calibrating coils near said magnetic generators and said magnetic field sensors out of contact therewith, and detecting calibrating magnetic fields generated by said calibrating coils with said magnetic generators and said magnetic field sensors to measure initial positions and initial directions of said magnetic generators and said magnetic field sensors when said two objects are not moving relatively to each other;
- removing said calibrating coils, and thereafter detecting a measuring magnetic field generated by one of said magnetic generators with one of said magnetic field sensors while electromagnetic coupling combinations between said magnetic generators and said magnetic field sensors are being switched by electromagnetic coupling switching means;
- and
- determining relative positions and directions of said magnetic generators with respect to said magnetic field sensors from magnetic fields detected by said magnetic field sensors, and calculating relative movement between said two objects.
Dependencies are inferred from the claim text.