RationalDMIS 2020 相对测量

有些零件尺寸大、装配比较复杂，因为各种原因产生了部分形变或者某些装配件的移位，比如整车或分总成的装配件；这时，仍按照原来的总零件坐标系进行原程序的自动化检测，测针会发生碰撞，或者出现找不到特征的情况。所以，分析一下，虽然整体发生了较大的形变，但是一个小范围内的装配部件上的特征之间的相对位置可能保持的比较好，那么，我们可以采用新的小范围内的参考坐标系，或者，采用参考特征的相对位置的测量。

无需编写程序，RationalDMIS 2020提供内置的相对测量功能。

相对测量是指在测量特征时，选择一个已经测量过的特征作为参考特征，然后根据被测特征理论值与参考特征理论值之间位置的关系，由参考特征的实测值重新计算被测特征的目标值，并根据这个目标值去测量被测特征。即使工件总坐标系发生了较大偏差，只要特征之间的相对位置不变，就仍然可以实现自动测量。

如图，测量过程中根据实际情况，既可以相对于“单一元素”测量，也可以相对于“多个元素”测量。下面举例说明。

(1)相对测量/默认 (I,J,K, T)：仅仅需要相对测量调整特征的方向；

MODE/PROG,MAN
F(CIR1)=FEAT/CIRCLE,INNER,CART,31.5000,31.5000,-3.0000,0.0000,0.0000,1.0000, 20.0000
$$ Measurement points are created through nominal points
MEAS/CIRCLE, F(CIR1), 4
  PTMEAS/CART, 24.4289, 24.4289, -3.0000,  0.7071,  0.7071, 0.0000
  GOTO/CART,   28.8212, 25.0328, -3.0000
  GOTO/CART,   31.5000, 24.5000, -3.0000
  GOTO/CART,   34.1788, 25.0328, -3.0000
  PTMEAS/CART, 38.5711, 24.4289, -3.0000, -0.7071,  0.7071, 0.0000
  GOTO/CART,   37.9672, 28.8212, -3.0000
  GOTO/CART,   38.5000, 31.5000, -3.0000
  GOTO/CART,   37.9672, 34.1788, -3.0000
  PTMEAS/CART, 38.5711, 38.5711, -3.0000, -0.7071, -0.7071, 0.0000
  GOTO/CART,   34.1788, 37.9672, -3.0000
  GOTO/CART,   31.5000, 38.5000, -3.0000
  GOTO/CART,   28.8212, 37.9672, -3.0000
  PTMEAS/CART, 24.4289, 38.5711, -3.0000,  0.7071, -0.7071, 0.0000
ENDMES
F(CIR2)=FEAT/CIRCLE,INNER,CART,52.4500,11.5500,-3.0000,0.0000,0.0000,1.0000, 6.7960
$$ Measurement points are created through nominal points
RMEAS/CIRCLE, F(CIR2), 4, FA(CIR1)
  GOTO/CART,   26.5502, 36.4498, 18.0000
  GOTO/CART,   52.1631, 11.8258, 18.0000
  PTMEAS/CART, 50.0004, 13.9050, -3.0000,  0.7209, -0.6931, 0.0000
  PTMEAS/CART, 50.0950,  9.1004, -3.0000,  0.6931,  0.7209, 0.0000
  PTMEAS/CART, 54.8996,  9.1950, -3.0000, -0.7209,  0.6931, 0.0000
  PTMEAS/CART, 54.8050, 13.9996, -3.0000, -0.6931, -0.7209, 0.0000
ENDMES

(2)相对测量/常规 (I,J,K, X,Y,Z)：需要同时对测量元素的方向和位置进行调整。

如图所示假定要测量一个平面PLN1和平面上的一个圆CIR 1。此时可以选择“相对测量/默认 (I,J,K, T)”模式，先测量平面，在测量圆时在相对测量对话框选择“相对单一元素”中将平面PLN1作为其相对测量的特征，PC-DMIS会参考平面（PLN1）的矢量方向对圆的测量位置进行调整重新计算圆的测量位置，自动测量圆CIR 1。

F(PLN1)=FEAT/PLANE,CART,32.1255,35.6836,0.0000,0.0000,0.0000,1.0000
$$ Measurement points are created through nominal points
MEAS/PLANE, F(PLN1), 4
  PTMEAS/CART,  3.0874, 51.5298, 0.0000, 0.0000, 0.0000, 1.0000
  PTMEAS/CART,  4.0665, 15.8134, 0.0000, 0.0000, 0.0000, 1.0000
  PTMEAS/CART, 59.6224,  6.4882, 0.0000, 0.0000, 0.0000, 1.0000
  PTMEAS/CART, 61.7258, 68.9028, 0.0000, 0.0000, 0.0000, 1.0000
ENDMES
$$ Measurement points are created through nominal points
RMEAS/CIRCLE, F(CIR1), 4, FA(PLN1)
  GOTO/CART,   61.7258, 68.9028, 18.0000
  GOTO/CART,   35.8998, 36.9445, 18.0000
  PTMEAS/CART, 37.7854, 39.2778, -3.0000, -0.6285, -0.7778, 0.0000
  GOTO/CART,   33.4813, 38.2137, -3.0000
  GOTO/CART,   30.7613, 38.4609, -3.0000
  GOTO/CART,   28.1537, 37.6483, -3.0000
  PTMEAS/CART, 23.7222, 37.7854, -3.0000,  0.7778, -0.6285, 0.0000
  GOTO/CART,   24.7863, 33.4813, -3.0000
  GOTO/CART,   24.5391, 30.7613, -3.0000
  GOTO/CART,   25.3517, 28.1537, -3.0000
  PTMEAS/CART, 25.2146, 23.7222, -3.0000,  0.6285,  0.7778, 0.0000
  GOTO/CART,   29.5187, 24.7863, -3.0000
  GOTO/CART,   32.2387, 24.5391, -3.0000
  GOTO/CART,   34.8463, 25.3517, -3.0000
  PTMEAS/CART, 39.2778, 25.2146, -3.0000, -0.7778,  0.6285, 0.0000
ENDMES

当然也可以相对多个元素特征，如下图。下图已三个平面基准：PLA1、PLA2、PLA3作为相对元素，X:PLA3，Y:PLA2，Z:PLA1，测量圆柱特征：CYL1。

F(PLN1)=FEAT/PLANE,CART,32.1255,35.6836,0.0000,0.0000,0.0000,1.0000
$$ Measurement points are created through nominal points
MEAS/PLANE, F(PLN1), 4
  PTMEAS/CART,  3.0874, 51.5298, 0.0000, 0.0000, 0.0000, 1.0000
  PTMEAS/CART,  4.0665, 15.8134, 0.0000, 0.0000, 0.0000, 1.0000
  PTMEAS/CART, 59.6224,  6.4882, 0.0000, 0.0000, 0.0000, 1.0000
  PTMEAS/CART, 61.7258, 68.9028, 0.0000, 0.0000, 0.0000, 1.0000
ENDMES
$$ Measurement points are created through nominal points
RMEAS/CIRCLE, F(CIR1), 4, FA(PLN1)
  GOTO/CART,   61.7258, 68.9028, 18.0000
  GOTO/CART,   35.8998, 36.9445, 18.0000
  PTMEAS/CART, 37.7854, 39.2778, -3.0000, -0.6285, -0.7778, 0.0000
  GOTO/CART,   33.4813, 38.2137, -3.0000
  GOTO/CART,   30.7613, 38.4609, -3.0000
  GOTO/CART,   28.1537, 37.6483, -3.0000
  PTMEAS/CART, 23.7222, 37.7854, -3.0000,  0.7778, -0.6285, 0.0000
  GOTO/CART,   24.7863, 33.4813, -3.0000
  GOTO/CART,   24.5391, 30.7613, -3.0000
  GOTO/CART,   25.3517, 28.1537, -3.0000
  PTMEAS/CART, 25.2146, 23.7222, -3.0000,  0.6285,  0.7778, 0.0000
  GOTO/CART,   29.5187, 24.7863, -3.0000
  GOTO/CART,   32.2387, 24.5391, -3.0000
  GOTO/CART,   34.8463, 25.3517, -3.0000
  PTMEAS/CART, 39.2778, 25.2146, -3.0000, -0.7778,  0.6285, 0.0000
ENDMES
F(PLN2)=FEAT/PLANE,CART,33.0151,0.0000,-13.8302,-0.0000,-1.0000,-0.0000
$$ Measurement points are created through nominal points
MEAS/PLANE, F(PLN2), 4
  PTMEAS/CART,  7.4489, 0.0000,  -3.4300, -0.0000, -1.0000, -0.0000
  PTMEAS/CART,  2.9630, 0.0000, -23.7844, -0.0000, -1.0000, -0.0000
  PTMEAS/CART, 61.7692, 0.0000, -25.6209, -0.0000, -1.0000, -0.0000
  PTMEAS/CART, 59.8793, 0.0000,  -2.4856, -0.0000, -1.0000, -0.0000
ENDMES
F(PLN3)=FEAT/PLANE,CART,0.0000,31.4812,-15.6828,-1.0000,-0.0000,-0.0000
$$ Measurement points are created through nominal points
MEAS/PLANE, F(PLN3), 4
  PTMEAS/CART, 0.0000,  4.8343, -26.0351, -1.0000, 0.0000, 0.0000
  PTMEAS/CART, 0.0000,  9.6750,  -4.8825, -1.0000, 0.0000, 0.0000
  PTMEAS/CART, 0.0000, 54.1767,  -6.6016, -1.0000, 0.0000, 0.0000
  PTMEAS/CART, 0.0000, 57.2388, -25.2118, -1.0000, 0.0000, 0.0000
ENDMES
F(CYL1)=FEAT/CYLNDR,INNER,CART,31.5000,31.5000,-4.0000,0.0000,0.0000,1.0000, 20.0000,  8.0000
 
$$ Measurement points are created through nominal points
RMEAS/CYLNDR, F(CYL1), 5, FA(PLN3), XDIR, FA(PLN2), YDIR, FA(PLN1), ZDIR
  PTMEAS/CART, 38.5711, 38.5711, -7.0000, -0.7071, -0.7071, -0.0000
  PTMEAS/CART, 38.5711, 38.5711, -1.0000, -0.7071, -0.7071, -0.0000
  GOTO/CART,   34.1788, 37.9672, -2.0000
  GOTO/CART,   31.5000, 38.5000, -3.0000
  GOTO/CART,   28.8212, 37.9672, -4.0000
  PTMEAS/CART, 24.4289, 38.5711, -5.0000,  0.7071, -0.7071,  0.0000
  GOTO/CART,   25.0328, 34.1788, -4.5000
  GOTO/CART,   24.5000, 31.5000, -4.0000
  GOTO/CART,   25.0328, 28.8212, -3.5000
  PTMEAS/CART, 24.4289, 24.4289, -3.0000,  0.7071,  0.7071,  0.0000
  GOTO/CART,   28.8212, 25.0328, -3.0000
  GOTO/CART,   31.5000, 24.5000, -3.0000
  GOTO/CART,   34.1788, 25.0328, -3.0000
  PTMEAS/CART, 38.5711, 24.4289, -3.0000, -0.7071,  0.7071,  0.0000
ENDMES