Apparatus and method for analyzing motions using bio-impedance

A method of measuring bio-impedance attributable to joint movement, comprising the steps:

• generating a weak current by use of a constant current source;
• causing the weak current to flow from a point to another point;
• forming L voltage detecting electrode pairs from voltage detecting electrodes positioned at m points on each of n−1 lines that divide an interval between a first joint and a second joint, between which the weak current flows, into equal n parts (m and n are natural numbers), using combination (mC2=L);
• detecting bio-impedance at certain periods from J (L−K) voltage detecting electrode pairs that are obtained by subtracting K voltage detecting electrode pairs, each of which exists on a single dividing line, from the formed L voltage detecting electrode pairs;
• and
• selecting a pair of voltage detecting electrodes having a highest variation of bio-impedance.

A system for analyzing joint movement using variations of bio-impedance attributable to the joint movement, comprising:

• a constant current source comprised of an oscillation frequency circuit and a voltage-to-current conversion circuit for generating a weak current;
• current stimulus electrodes for allowing the weak current to flow from a point of a living body to another;
• a first channel comprised at least two voltage detection electrodes which positioned in a certain region between a hip joint and a knee joint, a demodulator, a gain and offset controller and an isolated amplifier;
• a second channel comprised at least two voltage detection electrodes which positioned in a certain region between the hip joint and an ankle joint, a demodulator, a gain and offset controller and an isolated amplifier;
• a third channel comprised at least two voltage detection electrodes which positioned in a certain region between a knee joint and the ankle joint, a demodulator, a gain and offset controller and an isolated amplifier;
• a fourth channel comprised at least two voltage detection electrodes which positioned in a certain region between the knee joint and toes, a demodulator, a gain and offset controller and an isolated amplifier;
• an Analog/Digital (A/D) converter for converting signals output from the channels into digital signals;
• and
• a control unit for calculating the digital signals output from the A/D converter into angular variations of the joints.