Relative position and/or posture measuring system for measuring relative positions and/or relative postures using a magnetic field generator and a magnetic field detector
View Patent ↗The present invention provides a relative position and/or posture measuring system for measuring relative positions and relative postures between a magnetic field generator and a magnetic field detector by detecting a change in a magnetic field, in which the magnetic field generator includes a clock generator, a plurality of M-sequential code generators, a plurality of spread code generators, a plurality of integrators, and a voltage to current converter, and transmission coils TX, TY, TZ generate magnetic fields according to driving currents based on spread code obtained by converting code sequences generated by the M-sequential code generators to spread code with the spread code generators. The magnetic field detector reversely spreads received magnetic field detection values to obtain a magnetic field amplitude, and computes relative positions and relative postures of the two from the magnetic field amplitude.
1. A relative position and/or posture measuring system comprising:
a magnetic field generator including a plurality of transmission coils arrayed orthogonal to each other for generating a magnetic field from each transmission coil;
a magnetic field detector for receiving the magnetic field generated in each transmission coil as a magnetic field detection value for each transmission coil; and
a computing unit for computing a distance between and relative postures of the magnetic field generator and the magnetic field detector based on the magnetic field detection value for each transmission coil received by the magnetic field detector,
wherein the magnetic field generator comprises a clock generator for generating a clock signal with a 50% duty cycle;
a plurality of M-sequential code generators for generating code sequences different from each other from the clock signal given by the clock generator;
a plurality of spread code generators each for converting each code sequence to spread code by computing an exclusive logical sum of a code sequence generated by each M-sequential code generator and a clock signal generated by the clock generator;
a plurality of integrators each for generating a waveform obtained by integrating each spread code generated by each spread code generator; and
a voltage to current converter for converting a waveform generated by each integrator to a voltage waveform and providing a driving current to each transmission coil by means of voltage to current conversion, and
the computing unit computes the distance between the relative postures of the magnetic field generator and the magnetic field detector based on an amplitude of a magnetic field detection value obtained by reverse spreading of the spread code corresponding to the detected magnetic field detection value for each transmission coil.
2. The relative position and/or posture measuring system according to claim 1 ,
wherein the magnetic field detector comprises a plurality of receiving coils corresponding to the plurality of transmission coils, and
the computing unit reversely spreads the magnetic field detection values transmitted from each transmission coils and received by each receiving coils according to the spread code to obtain magnetic field amplitude values by the number obtained by multiplying the number of receiving coils by the number of transmission coils, and generates simultaneous equations from these magnetic amplitude values to compute the distance between and the relative postures between the magnetic field generator and the magnetic field detector.
3. The relative position and/or posture measuring system according to claim 2 ,
wherein at least three or more transmission coils and receiving coils are provided respectively,
each of the receiving coils detects at least three magnetic field detection values generated by the transmission coils, and
the computing unit generates 9 or more simultaneous equations based on at least 9 or more magnetic field detection values to compute relative position coordinate information for the magnetic field generator and the magnetic field detector in a three-dimensional space as well as relative posture information of the magnetic field generator and the magnetic field detector defined by an Euler angle.