FBG-based torsion sensor device

A torsion sensor device which measures a degree of torsion of a measurement object by using a fiber Bragg grating (FBG) sensor, the torsion sensor device comprising:

• an FBG sensor including a sensing unit formed in one section of an optical fiber;
• and
• a fixing device for fixing and supporting the FBG sensor to cause displacement of the FBG sensor according to motion of the measurement object,
• wherein the fixing device includes a bending prevention member to enable the sensing unit to have torsion displacement without bending displacement, according to the motion of the measurement object,
• wherein the bending prevention member includes:
• two supports to support the FBG sensor to allow the torsion displacement of the sensing unit;
• and a reinforcer connecting the two supports to prevent a relative bending movement between each support,
• wherein the fixing device further includes a beam to which the FBG sensor is attached, wherein the beam makes a twisting motion in response to a twisting movement of the measurement object, and the beam is positioned across the two supports and fixed to the supports, and
• wherein the support is a ball bearing, the beam is fixed to an inner ring of the ball bearing, and the reinforcer is fixed to an outer ring of the ball bearing.