非接触磁耦合光纤光栅位移传感器

Non-Contact Magnetic Coupling Fiber Bragg Grating Displacement Sensor

研发了一种基于光纤Bragg光栅(fiber Bragg grating,FBG)技术的非接触磁耦合位移传感器.两块扁圆柱型硬磁铁通过软铁连接起来,形成一U型传感探头.该U型探头与被测物形成一闭合磁路,实现间隙与磁耦合力的转换,再通过一平面薄板结构将磁耦合力转变为光纤FBG的轴向应变.通过理论和实验详细地分析研究了上述两个关键技术环节.研究表明:该非接触位移传感器为一非线性传感器,非线性主要是由于磁耦合力与间隙的平方成反比这一传感器固有特性以及漏磁,特别是漏磁随间隙增加而变大造成的.该非线性传感器的数据处理结果为:随机不确定度为0.23%;回程误差为0.376%;传感器综合误差为±0.606%.

A non-contact magnetic coupling displacement sensor based on fiber Bragg grating （FBG）sensing technology was developed. Two pieces of flat cylinder-shaped permanent magnet were linked by soft magnetic material to form a U-type sensing probe. Thus a closed magnetic circuit was formed from this U-type probe and the measured moving object, by which the transferring relation between the gap and magnetic field force can be established, and then by means of a mechanical transducer based on planar circular sheet, the magnetic coupling force can be converted into the sensing FBG axial strain. The above two key techniques were analyzed theoretically and experimentally. Results indicate that this non-contact displacement cell is a nonlinear sensor, this nonlinearity is produced mainly by the sensor inherent characteristic that the magnetic filed force is inversely proportional to the square of the gap, and the magnetic leakage which is increased with the increase of the gap. The data processing results show that the repeatability and hysteresis of the nonlinear sensor over the full displacement range are 0.23% and 0.376%,respectively. Therefore,the resultant error achieved is ±0.606% over the full range.