新型绝对式磁栅位移传感器的设计

Design of a New Kind of Absolute Magnetic Grid Displacement Sensor

为吸取磁栅位移传感器的优点并避免精度和分辨率较低的问题,设计了一种新型的磁栅位移传感器,磁头由线性霍尔元件阵列组成,磁栅由永磁体阵列构成。为提高原始电压信号的质量,采用三相六元件的信号发生方案,通过差分处理滤除了由于装配偏差和零点漂移带来的信号误差,并对磁栅信号发生装置结构进行了ANSYS有限元电磁场分析,依据磁场分析的结果选择磁头安装间隙。在磁栅绝对位移实现方面,采用两排磁钢的方法,一排编码,记录磁头所在的周期;一排用来记录每个正弦周期的相对位移。相对位移选择了基于查表方式的信号处理算法,降低了处理芯片的运算量,并通过对高性能的16位嵌入式单片机dsPIC33FJ64MC706的开发实现了此算法。简化了信号处理硬件的外围电路,满足了磁栅小型化的设计要求,而且实现了磁栅高速的运算能力和实时的信号处理功能,提高了磁栅的分辨率和工作可靠性。

In order to make use of the magnetic grid displacement sensor and to avoid the lower accuracy and resolu- tion problems, a new kind of magnetic grid displacement sensor was proposed, which was composed of magnetic head and magnetic grid. The magnetic head was constituted by linear hall element arrays, and the magnetic grid con- sisted of permanent magnet arrays. In order to enhance the quality of original voltage signal, the signal generator a- dopted three-phase and six components. The errors caused by assemble and zero drift were eliminated through difference processing, while the electromagnetic field of magnetic signal generator was analyzed by ANSYS. The as- semblage gap of magnetic head was selected according to the analysis results. Absolute displacement magnetic grid was realized by two rows magnet steels. One magnet steel was used to encode column and record the cycle series, the other was used to record relative displacement of every sine cycle. A look-up table technique was presented when relative displacement dealt with magnetic grid signal, which could decrease the computational complexity of the pro- cessing chip. The method was realized through the flush type SCM （dsPIC33FJ64MC706） with 16 bits. The periph- eral circuit of the signal processing hardware was simplified, which not only satisfied the requirements of miniaturi- zation design, but also realized magnetism grid＇s high speed operational capability and the real-time signal processing function, and increased the resolution and reliability of the magnetic grid displacement sensor.