Control computer and method of controlling robotic arm

摘要

A computer determines a first origin of a first coordinate system of a PCB, and controls a robotic arm to position a probe above the first origin. Furthermore, the computer determines a second origin of a second coordinate system of the robotic arm, and determines displacement values from the first origin to a test point in controlling movements of the robotic arm in the second coordinate system. A graph representing the test point is recognized in an image of the PCB, pixel value differences between the graph center and the image center are determined and converted to displacement correction values for controlling the movements of the robotic arm and determining 3D coordinates of the test point. The robotic arm is moved along a Z-axis of the second coordinate system to precisely position the probe on the test point of the PCB.

主权项

1. A computer-based method of controlling a robotic arm being performed by execution of computer readable program code by a processor of a control computer, the method comprising:
executing, by the processor, the steps of: (a) reading a layout file from a storage device, and determining an origin P0(x0, y0) of a first coordinate system of a printed circuit board (PCB) according to layout information in the layout file; (b) generating a first control command to a robotic arm configured to hold a probe of a test device and position the held probe directly above the origin P0(x0, y0) of the first coordinate system; (c) determining an origin Q0(X0, Y0, Z0) of a second coordinate system of the robotic arm based on the origin Pn(x0, y0) of the first coordinate system and an initial distance Z0 from the probe to the PCB; (d) reading coordinate information and size information of a test point Pn(xn, yn) of the PCB from the layout file, wherein n has an initial value of 1, and determining displacement values dX(n) and dY(n) from the test point Pn(xn, yn) to the origin P0(x0, y0); (e) generating a second control command configured to control movements of the robotic arm in the second coordinate system according to the displacement values; (f) capturing an image of the PCB, recognizing the test point Pn(xn, yn) represented by a graph in the image based on the layout information; (g) determining pixel value differences DX and DY between the center of the graph and the center of the image, and converting the pixel value differences DX and DY to displacement correction values dXr(n) and dYr(n) of the robotic arm according to a zoom ratio of the image to the PCB; (h) generating a third control command configured to control the movements of the robotic arm in the second coordinate system according to the displacement correction values dXr(n) and dYr(n); (i) determining three-dimensional (3D) coordinates (Xn, Yn, Zn) of the test point Pn(xn, yn) in the second coordinate system according to the displacement correction values dXr(n) and dYr(n) and a current distance Zn from the probe to the PCB, wherein Xn=xn+dXr(n), Yn=yn+dYr(n); and (j) generating a fourth control command configured to move the robotic arm along a negative Z-axis direction of the second coordinate system by a distance of Zn, to precisely position the probe on the test point Pn(xn, yn) of the PCB and test the test point Pn(xn, yn) by the test device.