Abstract: Aiming at the problems of mutual crosstalk among magnetic fields affecting the measurement accuracy of the sensors and reducing the signal-to-noise ratio when the excitation frequency of two code channels of a dual-row planar magnetic field sensor was the same， a multi-frequency magnetic field coupled absolute linear time-grid displacement sensor design scheme was proposed， which achieved the solution to the problems of eliminating the crosstalk of the magnetic fields among the code channels while solving the absolute displacement. The sensor was divided into fixed scale and dynamic scale， both using double-layer alternating structure， fixed scale using two columns of incremental code channel combination， divided into fine and coarse machines， the pairs of poles of two rows of excitation coils were two integers of the reciprocal relation， the absolute displacement measurement was realized by using the pairs of poles within the displacement difference. Precision machine measurement channel and rough machine measurement channel were input  different frequencies of the excitation current signals at the same time，  the precision machine was input the 1 MHz high-frequency current signals， the high-frequency excitation current signals might effectively enhance the inductive signals， improve the signal-to-noise ratio of the electrical processing system. Through the method of outlier frequency reduction， the sensor resolution was improved， which effectively solved the problems that it were difficult to reconcile the signal-to-noise ratio enhancement of the signals by increasing the frequency of the excitation signals and the high resolution of the sensors. Theoretical validation and error analysis of the sensors were carried out through electromagnetic simulation analysis. Finally， the experimental platform was built to carry out prototype experiments， and the experimental results show that the absolute sensor structure with multi-frequency magnetic field coupling effectively eliminates the magnetic field crosstalk between the fine and coarse machines， and the signal-to-noise ratio of the sensors is improved， with measurement errors are less than ±17.34 μm in the measurement range of 140 mm. 

Key words: absolute displacement measurement, multi-frequency magnetic field coupling, signal-to-noise ratio, displacement sensor

摘要： 针对双列平面磁场式传感器两码道激励频率相同时磁场之间的相互串扰影响传感器测量精度并降低信噪比等问题，提出了一种多频磁场耦合的绝对式直线时栅位移传感器设计方案，在实现解算绝对位移的同时能够消除码道间磁场串扰的问题。传感器分为定尺和动尺，都采用双层交替结构，定尺使用两列增量式码道组合而成，分为精机和粗机，两列激励线圈的对极数为互质关系的两个整数，利用对极内位移差实现绝对位移测量。精机测量通道和粗机测量通道同时通入不同频率的激励电流信号，其中精机为1 MHz高频电流信号，高频激励电流信号可以有效增强感应信号，提高电气处理系统的信噪比。通过外差降频的方法来提高传感器分辨力，有效地解决了通过提高激励信号频率来提高信号信噪比与传感器解算高分辨力难以兼顾的问题。通过电磁仿真分析对传感器进行了理论验证和误差分析。最后搭建实验平台进行了样机实验，实验结果表明，采用多频磁场耦合的绝对式传感器结构有效消除了精机与粗机之间的磁场串扰，传感器信噪比得到提高，在140 mm的测量范围内测量误差小于±17.34 μm。

关键词: 绝对位移测量, 多频磁场耦合, 信噪比, 位移传感器