基于非线性磁场耦合的寄生式时栅位移测量方法

Measurement method for displacement shift of the parasitic time grating based on nonlinear magnetic coupling

由于大型机床的回转工作台具有大型、中空、强冲击振动等特点,在闭环控制过程中无法安装传统角编码器,而现有检测方法具有安装要求高、精度无法保证等问题,提出一种利用与转台同轴刚性连接的蜗轮的齿槽等分特性实现角度测量的寄生式时栅测量方法。首先利用蜗轮蜗杆齿面坐标变换和啮合方程,建立蜗轮齿顶面数学模型;其次采用分段函数方法研究传感单元与蜗轮齿顶面磁场耦合面积变化,建立非线性磁场耦合条件下的位移传感理论模型。在特定蜗轮和传感器参数条件下,对传感器建模并进行有限元仿真。根据仿真结果修正理论模型,优化传感器结构并制作原理样机,搭建实验平台进行实验验证。实验结果表明,在整周范围内传感器静态测量误差峰峰值达到7″,为应用于非线性磁场耦合条件下的寄生式时栅位移传感器开发提供了理论依据。

Considering that the rotating table of the large-scale machine tool has the characteristics of large, hollow, strong impact and vibration, the traditional angular displacement sensor can＇ t be coaxially mounted. Meanwhile, existing measurement method has disadvantages of rigorous installation requirement and stability of precision, a measurement method for the parasitic Time Grating is proposed. With the slot and the tooth of the worm wheel which are uniform-spaced and solid coupling with the rotating table, the angle is measured. Based on the transformation of coordinates and the mesh equation, the mathematical model of magnetic coupling is established. Research on the magnetic coupling area variation between the sensor element and the worm wheel, the displacement sensing model in the condition of nonlinearity magnetic coupling is presented. The sensor is modeled and analyzed by the finite element emulation. Theoretical model is modified, and the structure of sensor is optimized. A sensor prototype and experimental platform are designed. According to the accuracy test, the accuracy of static measurement is 7＂ in the range of 0 to 360°. Theoretical foundation is provided for the development of the parasitic Time Grating in the condition of nonlinearity magnetic coupling.