Square Layout Four-Point Method for Two-Dimensional Profile Measurement and Self-Calibration Method of Zero-Adjustment Error
Square Layout Four-Point Method for Two-Dimensional Profile Measurement and Self-Calibration Method of Zero-Adjustment Error
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DOI：
10.20965/ijat.2018.p0707
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发表时间：
2018-09
期刊：
影响因子：
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通讯作者：
H. Shimizu;Ryousuke Yamashita;Takuya Hashiguchi;T. Miyata;Yuuma Tamaru
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作者：
H. Shimizu;Ryousuke Yamashita;Takuya Hashiguchi;T. Miyata;Yuuma Tamaru
提出了一种平面加工表面二维轮廓度的在线测量方法--带角度补偿的四点法。在该方法中，将四个位移传感器布置在一个正方形中，并安装在二维工作台的扫描台上。为了测量目标平面的二维轮廓，通过栅格扫描运动获取对应于所有测量点的高度数据。同时，利用两个自动准直器对第一主扫描线的俯仰数据和第一副扫描线的滚动数据进行监测，以补偿由姿态误差引起的主要轮廓误差。SLFP方法的使用有助于将通过使用两个附加传感器和第一辅助扫描线的滚动数据获得的每条扫描线的直线度测量结果连接在一起。具体地，通过使用三个邻接点的预定高度数据以及由四个位移传感器获取的数据的递归方程来计算测量点的高度。数值模拟结果表明，带角度补偿的SLFP方法具有较高的计算效率。然而，在实际测量过程中，很难将每个位移传感器的原点高度完美对准。关于SLFP方法，零点调整误差被定义为传感器原点相对于由其他三个传感器原点组成的平面的相对高度。该误差与应用递归方程的次数成比例累积。包含调零误差的仿真结果表明，该误差的累积将导致测量结果的不可忽略的失真。为此，提出了一种新的调零误差自标定方法。在二维轮廓测量过程中，可以使用两种不同的计算路径--栅格扫描路径和正交路径--来确定测量点的高度。尽管通过使用两个路径确定的高度理想上必须相等，但观察到它们是不同的，因为两个路径的累积零点调整误差不同。根据这一结果，可以对调零误差进行反向计算和校准。通过仿真和实验验证了该标定方法的有效性。
An on-machine measurement method, called the square-layout four-point (SLFP) method with angle compensation, for evaluating two-dimensional (2-D) profiles of flat machined surfaces is proposed. In this method, four displacement sensors are arranged in a square and mounted to the scanning table of a 2-D stage. For measuring the 2-D profile of a target plane, height data corresponding to all measuring points are acquired by means of the raster scanning motion. At the same time, pitching data of the first primary scan line and rolling data of the first subsidiary scan line are monitored by means of two auto-collimators to compensate for major profile errors that arise out of the posture error. Use of the SLFP method facilitates connection of the results of straightness-measurements results obtained for each scanning line by using two additional sensors and rolling data of the first subsidiary scan line. Specifically, the height of a measuring point is calculated by means of a recurrence equation using three predetermined height data for adjacent points in conjunction with data acquired by the four displacement sensors. Results of the numerical simulation performed in this study demonstrate higher efficiency of the SLFP method with angle compensation. During actual measurement, however, it is difficult to perfectly align inline the origin height of each displacement sensor. With regard to the SLFP method, zero-adjustment error is defined as the relative height of a sensor’s origin with respect to the plane comprising origins of the other three sensors. This error accumulates in proportion to number of times the recurrence equation is applied. Simulation results containing the zero-adjustment error demonstrate that accumulation of the said error results in unignorable distortion of measurement results. Therefore, a new self-calibration method for the zero-adjustment error has been proposed. During 2-D profile measurement, two different calculation paths – the raster scan path and orthogonal path – can be used to determine the height of a measurement point. Although heights determined through use of the two paths must ideally be equal, they are observed to be different because accumulated zero-adjustment errors for the two paths are different. In view of this result, the zero-adjustment error can be calculated backwards and calibrated. Validity of the calibration method has been confirmed via simulations and experiments.