CN102581851A - Mechanical arm movement control system and method - Google Patents

Abstract

A motion control system for a mechanical arm runs on a control computer. The system determines the origin of the mechanical arm coordinate system according to the origin of the PCB coordinate system and the distance between the probe and the PCB to be tested, and calculates the relative displacement value between the test point and the origin of the PCB coordinate system according to the two-dimensional coordinates of the test point on the PCB, and according to The relative displacement value controls the corresponding displacement of the robot arm in the coordinate system of the robot arm. The system also calculates the pixel difference between the center point of the geometry of the test point in the current image of the PCB and the center point of the current image, calculates the displacement correction of the robot arm, and makes corresponding corrections to the displacement of the robot arm in the coordinate system of the robot arm, so as to The probes are positioned directly over this test point on the PCB. After that, the system controls the mechanical arm to make a corresponding displacement along the Z-axis according to the distance between the probe and the test point on the PCB, so that the probe can be precisely positioned on the test point on the PCB. The invention also provides a motion control method of the mechanical arm.

Description

Robotic arm motion control system and method

technical field

The invention relates to an automatic measurement system and method, in particular to a motion control system and method of a mechanical arm.

Background technique

At present, robotic arms are widely used in the field of automated measurement. In the measurement process, the test tool (such as a probe) is generally grasped by a mechanical arm, and the test tool is positioned on the product to be tested according to the coordinate information of the test points recorded in the layout file of the product to be tested (such as a PCB). corresponding position. On the one hand, since the coordinate information recorded in the layout file of the product to be tested is usually based on a linear rectangular coordinate system, and the movement of the robotic arm is driven by the rotation of multiple driving motors, the movement of the driving motor is based on polar coordinate information. That is to say, the coordinate system of the robotic arm is nonlinear. On the other hand, a test point is generally a pad for soldering a component (such as a capacitor) to a PCB, but actually has a certain size and is not a simple "point". Therefore, there is a certain error in controlling the movement of the robotic arm directly according to the coordinate information of the test points recorded in the layout file of the product to be tested.

Contents of the invention

In view of the above, it is necessary to propose a mechanical arm motion control system and method, which can correct the motion of the mechanical arm and improve the accuracy of the mechanical arm motion control.

A motion control method of a mechanical arm is operated on a control computer. The method includes: (a) reading the layout file of the PCB to be tested to obtain the layout information of the PCB to be tested, including the origin coordinates (x0, y0) of the PCB coordinate system to be tested, the information of the parts to be tested and the information of the test points ; (b) Generate the first control instruction according to the origin coordinates (x0, y0) of the PCB coordinate system to be tested to control the mechanical arm to move the probe to directly above the origin (x0, y0) of the PCB coordinate system to be tested; (c) use the laser The range finder measures the distance Z0 between the probe grabbed by the robot arm and the PCB to be tested; (d) determine the coordinates of the robot arm according to the origin coordinates (x0, y0) of the PCB coordinate system to be tested and the distance Z0 between the probe and the PCB to be tested (X0, Y0, Z0); (e) read the two-dimensional coordinates of a test point on the PCB to be tested from the layout information, and calculate the relative displacement value between the test point and the origin of the PCB coordinate system to be measured; (f) Generate a second control command according to the calculated relative displacement value to control the mechanical arm to make a corresponding displacement in the mechanical arm coordinate system; (g) use the image capture device to capture the current image of the PCB to be tested; (h) according to the Measure the layout information of the PCB to determine the geometry of the test point in the current image, and calculate the pixel difference between the center point of the geometry of the test point in the current image and the center point of the current image; (i) according to the current image and the Measure the zoom ratio of the PCB and convert the pixel difference into the displacement correction of the mechanical arm in the mechanical arm coordinate system; (j) generate the third control command according to the calculated displacement correction to the displacement of the mechanical arm in the mechanical arm coordinate system Make corresponding corrections to position the probe directly above the test point on the PCB to be tested; (k) use a laser rangefinder to measure the current distance between the probe grabbed by the robotic arm and the test point on the PCB to be tested Zn; and (1) according to the current distance Zn of the probe and the test point on the PCB to be tested, the fourth control command is generated to control the mechanical arm to move negative Zn along the Z-axis direction, so that the probe is accurately positioned on the PCB to be tested. The test point.

A motion control system for a mechanical arm runs on a control computer. The system includes: an information reading module, a control module, a coordinate determination module, a calculation module and a graphic recognition module. The information reading module reads the layout file of the PCB to be tested to obtain the layout information of the PCB to be tested. The control module generates a first control command according to the origin coordinates (x0, y0) of the PCB coordinate system to be tested to control the mechanical arm to move the probe to directly above the origin (x0, y0) of the PCB coordinate system to be tested. The coordinate determining module determines the origin coordinates (X0, Y0, Z0) of the mechanical arm coordinate system according to the origin coordinates (x0, y0) of the PCB coordinate system to be tested and the distance Z0 between the probe and the PCB to be tested measured by the laser range finder. The calculation module calculates the relative displacement value between the test point on the PCB to be tested and the origin of the coordinate system of the PCB to be tested. The control module generates a second control instruction to control the mechanical arm to make a corresponding displacement in the mechanical arm coordinate system according to the calculated relative displacement value. The graphic recognition module determines the geometry of the test point in the current image of the PCB to be tested captured by the image capture device according to the layout information of the PCB to be tested. The calculation module calculates the pixel difference between the center point of the geometric figure of the test point in the current image and the center point of the current image, and converts the pixel difference into the coordinate system of the robot arm according to the scaling ratio of the current image and the PCB to be tested displacement correction. The control module generates a third control command according to the calculated displacement correction amount to correct the displacement of the mechanical arm in the mechanical arm coordinate system, and according to the distance between the probe measured by the laser rangefinder and the test point on the PCB to be tested The current distance Zn generates a fourth control command to control the mechanical arm to move negative Zn along the Z-axis direction, so that the probe can be accurately positioned to the test point on the PCB to be tested.

Compared with the prior art, the robot arm motion control system and method provided by the present invention use the image of the PCB to be tested captured by the image capture device to correct the two-dimensional plane recognized by the robot arm, and use the laser rangefinder to measure the mechanical The distance between the probe grasped by the arm and the test point on the PCB to be tested improves the accuracy of the motion control of the mechanical arm.

Description of drawings

FIG. 1 is an application environment diagram of a preferred embodiment of the robot arm motion control system of the present invention.

Fig. 2 is a functional block diagram of a preferred embodiment of the robot arm motion control system of the present invention.

FIG. 3A and FIG. 3B are flow charts of a preferred embodiment of the method for controlling the movement of the robotic arm of the present invention.

Fig. 4 is a schematic diagram of the coordinate system of the PCB to be tested and the coordinate system of the robot arm.

Description of main component symbols

control computer 10 Mechanical arm 20 Image capture device 30 Laser range finder 40 test instrument 50 PCB to be tested 60   Robotic arm motion control system 11 Information reading module 110 Graphic recognition module 111 Coordinate determination module 112 control module 113 Computing module 114 Layout file 12 memory 13 Processor 14

Detailed ways

As shown in FIG. 1 , it is an application environment diagram of a preferred embodiment of the robot arm motion control system 11 of the present invention. The robot arm motion control system 11 runs in the control computer 10 . The control computer 10 is respectively connected with the mechanical arm 20 , the image capture device 30 , the laser rangefinder 40 and the testing instrument 50 through data lines. The mechanical arm 20 grabs the probes of the test instrument 50 using the probe grabbing device. The image capture device 30 captures the image of the PCB 60 to be tested, and the laser rangefinder 40 measures the distance between the probes grabbed by the mechanical arm 20 and the PCB 60 to be tested.

It should be pointed out that, during the movement of the robotic arm 20 , the probe grasped by the robotic arm 20 is always located directly in front of the center of the lens of the image capture device 30 . The mechanical arm motion control system 11 controls the movement of the mechanical arm 20 in the X and Y axis directions of the mechanical arm coordinate system according to the coordinate information of the test point on the PCB 60 to be tested, and according to the image of the PCB 60 to be tested captured by the image capture device 30 The information corrects the movement of the mechanical arm 20, and finally controls the movement of the mechanical arm 20 in the Z-axis direction of the mechanical arm coordinate system according to the distance between the probe grasped by the mechanical arm 20 and the PCB 60 to be tested, so as to accurately position the probe to the PCB 60 to be tested. Test the test points on the PCB 60.

The image capture device 30 is a camera or a video camera, and the test instrument 50 is an oscilloscope or a time domain reflectometer. The PCB 60 to be tested is placed horizontally on the test platform. In other embodiments, the PCB 60 to be tested can also be other electronic components.

As shown in FIG. 2 , it is a functional block diagram of a preferred embodiment of the robot arm motion control system 11 of the present invention. The robot arm motion control system 11 includes an information reading module 110 , a pattern recognition module 111 , a coordinate determination module 112 , a control module 113 and a calculation module 114 . The modules 110 to 114 include programmed codes, which are stored in the memory 13 of the control computer 10 , and the processor 14 of the control computer 10 executes these programmed codes to provide the above-mentioned functions of the robot arm motion control system 11 . The specific functions of each module will be described below with reference to FIG. 3A and FIG. 3B .

Referring to FIG. 3A and FIG. 3B , it is a flow chart of a preferred embodiment of the method for controlling the movement of the robotic arm of the present invention.

In step S301, the information reading module 110 reads the layout file 12 of the PCB 60 to be tested from the memory 13. The layout file 12 records the layout information of the PCB 60 to be tested, including the origin coordinates (x0, y0) of the PCB60 coordinate system to be tested, the type of parts to be tested (such as resistance, capacitance, inductance), and various types to be tested. The quantity of parts, the size information of each part to be tested and the test point (pad) included on each part to be tested, the two-dimensional coordinates of each test point in the PCB 60 coordinate system to be tested and the size of each test point. For example, if the part to be tested (or test point) is a circle, the size information includes the radius, and if it is a rectangle, the size information includes length and width.

Step S302, the information reading module 110 reads the origin coordinates (x0, y0) of the PCB 60 to be tested.

Step S303, the control module 113 generates a first control instruction according to the origin coordinates (x0, y0) of the PCB 60 to be tested to control the mechanical arm 20 to move the probe to directly above the origin (x0, y0) of the PCB 60 to be tested.

Step S304, the image capture device 30 captures the initial image of the PCB 60 to be tested, and the pattern recognition module 111 recognizes the parts or test points represented by each geometric figure in the initial image according to the layout information in the layout file 12, and the parts or test points represented by the initial image parts and the distribution of test points to determine the origin position in the initial image.

Step S305 , the laser rangefinder 40 measures the distance Z0 between the probe grasped by the mechanical arm 20 and the PCB 60 to be tested.

Step S306, the coordinate determination module 112 is used to determine the origin coordinates (X0, Y0, Z0) of the mechanical arm coordinate system according to the origin coordinates (x0, y0) of the PCB 60 coordinate system to be measured and the distance Z0 between the probe and the PCB 60 to be measured, Where X0=x0, Y0=y0. As shown in Figure 4, the coordinate system of the mechanical arm is based on (X0, Y0, Z0) as the origin, and the straight line parallel to the x and y axes of the PCB 60 coordinate system to be measured is respectively the X and Y axes, so as to be in line with the measured PCB 60 coordinate system. The vertical direction of the PCB 60 coordinate system is the space coordinate system determined by the Z axis.

Step S307, the information reading module 110 reads the two-dimensional coordinates (xn, yn) and size information of the nth test point on the PCB 60 to be tested. Among them, the initial value of n is 1.

Step S308, the calculation module 114 calculates the relative displacement value between the nth test point and the origin of the PCB 60 coordinate system to be tested according to the two-dimensional coordinates (xn, yn) of the nth test point on the PCB 60 to be tested. For example, the relative displacement values of the nth test point on the PCB 60 to be tested and the origin (x0, y0) of the plane coordinate system are dX(n)=xn-x0, dY(n)=yn-y0.

In step S309, the control module 113 is used to generate a second control command according to the relative displacement value between each test point and the origin of the plane coordinate system to control the robot arm 20 to make a corresponding displacement in the robot arm coordinate system. For example, the robot arm 20 is controlled to move dX(n) along the X-axis direction of the robot arm coordinate system, and move dY(n) along the Y-axis direction.

In step S310, the image capture device 30 captures the current image of the PCB 60 to be tested.

Step S311, the pattern recognition module 111 determines the center point of the geometric figure of the nth test point according to the size information of the nth test point, and the calculation module 114 calculates the center point of the geometric figure of the nth test point in the current image The pixel difference between the point and the center point of the current image in the X and Y directions. For example, assuming that the resolution of the current image is 640*480 pixels, the pixel coordinates of the center point of the current image are (320, 240), assuming that the pixel coordinates of the center point of the geometry of the nth test point are (312, 234 ), then the pixel difference between the center point of the geometry of the nth test point and the current image center point is 320-312=8 along the X-axis direction of the mechanical arm coordinate system, and the pixel difference in the Y-axis direction is It is 240-234=6, and the unit is pixel.

In step S312, the calculation module 114 converts the pixel difference in the X and Y directions into the displacement corrections dXr(n) and dYr(n) of the robot arm in the X and Y directions according to the scaling ratio of the current image and the PCB 60 to be tested. The zoom ratio can be determined according to the magnification of the image capture device 30 . For example, assuming that the magnification of the image capture device 30 is 1:2, and the size of the PCB 60 to be tested is Lcm*H cm, then dXr(n)=(8/640)*L/2, dYr(n)=( 6/480)*H/2.

In step S313, the control module 113 generates a third control instruction to correct the displacement of the robot arm 20 in the robot arm coordinate system according to the calculated displacement correction amount. For example, control the mechanical arm 20 to continue to move dXr(n) along the X-axis direction of the mechanical arm coordinate system, and continue to move dYr(n) in the Y-axis direction, so as to position the probe to the nth test point on the PCB 60 to be tested. Directly above. The current X coordinate of the probe grasped by the mechanical arm 20 in the mechanical arm coordinate system is Xn=xn+dXr(n), and the Y coordinate is Yn=yn+dYr(n).

Step S314 , the laser rangefinder 40 measures the current distance Zn between the probe grasped by the mechanical arm 20 and the nth test point (xn, yn) on the PCB 60 to be tested.

Step S315, the coordinate determining module 112 is based on the coordinates of the test point on the PCB 60 to be tested in the PCB 60 coordinate system to be tested, the calculated displacement correction amount and the probe and the nth test point (xn, yn) determines the coordinates (Xn, Yn, Zn) of the nth test point in the mechanical arm coordinate system, and records the coordinates (Xn, Yn, Zn) of the nth test point in the mechanical arm coordinate system Zn) to memory 13. For example, the two-dimensional coordinates of the nth test point on the PCB 60 to be tested are (xn, yn), then the coordinates of the nth test point in the mechanical arm coordinate system are (Xn, Yn, Zn). Wherein, Xn=xn+dXr(n), Yn=yn+dYr(n).

Step S316, the control module 113 generates a fourth control instruction according to the current distance Zn between the probe grasped by the mechanical arm 20 and the nth test point on the PCB 60 to be tested, and controls the mechanical arm 20 to move negative Zn along the Z-axis direction to precisely position the probe Go to the nth test point on the PCB 60 to be tested, and test the nth test point.

Step S317, the information reading module 110 judges whether there are other test points not tested on the PCB 60 to be tested according to the layout information recorded in the layout file 12. If there are other test points that have not been tested, step S318 is executed, and the control module 113 generates a fifth control command to control the reset of the mechanical arm 20, that is, to control the mechanical arm 20 to reposition the probe to the origin of the mechanical arm coordinate system (X0, Y0, Z0). Afterwards, the process repeats from step S307 until all test points on the PCB 60 to be tested are tested, and the process ends.

Claims (10)

1. mechanical arm motion control method; Run on the control computer; This control computer expert crosses data wire and is connected with mechanical arm, image capture unit, radium-shine rangefinder and tester respectively; Mechanical arm utilizes the probe grabbing device to grasp the probe of tester, it is characterized in that this method comprises:

(a) read the cloth map file of PCB to be measured, obtain the layout information of PCB to be measured, comprise PCB coordinate system to be measured origin (x0, y0), the information of part to be measured and test point information;

(b) according to the origin of PCB coordinate system to be measured (x0 y0) produces first control instruction, control mechanical arm traveling probe to PCB coordinate origin to be measured (x0, y0) directly over;

(c) utilize probe that radium-shine stadia surveying mechanical arm grasps and PCB to be measured apart from Z0;

(d) according to the origin of PCB coordinate system to be measured (x0, y0) and probe and PCB to be measured apart from Z0 confirm the mechanical arm coordinate system origin (X0, Y0, Z0);

(e) from layout information, read the two-dimensional coordinate of the last test point of PCB to be measured, calculate the relative displacement value of this test point and PCB coordinate origin to be measured;

(f) produce second control instruction according to the relative displacement value that calculates, the control mechanical arm is done corresponding displacement in the mechanical arm coordinate system;

(g) utilize image capture unit to capture the current image of PCB to be measured;

(h) in current image, confirm the geometric figure of this test point according to the layout information of PCB to be measured, calculate the geometric central point of this test point and the pixel value difference of current image center point in current image;

(i) scaling according to current image and PCB to be measured converts pixel value difference the displacement correction amount of mechanical arm in the mechanical arm coordinate system into;

(j) give birth to the 3rd control instruction according to the displacement correction volume production that calculates, corresponding correction is done in the displacement in the mechanical arm coordinate system to mechanical arm, with probe is navigated to this test point on the PCB to be measured directly over;

(k) utilize the probe of radium-shine stadia surveying mechanical arm extracting and the current distance Zn of this test point on the PCB to be measured; And

(l) the current distance Zn according to this test point on probe and the PCB to be measured produces the 4th control instruction, and the control mechanical arm moves negative Zn along Z-direction, so that probe accurately navigates to this test point on the PCB to be measured.

2. mechanical arm motion control method as claimed in claim 1 is characterized in that, in the process of mechanical arm motion, the probe that mechanical arm grasps is positioned at the dead ahead of the optical center point of image capture unit all the time.

3. mechanical arm motion control method as claimed in claim 1; It is characterized in that this method also comprises step: the distance according to this test point on coordinate, the displacement correction amount that calculates and the probe and the PCB to be measured of this test point in PCB coordinate system to be measured is confirmed the coordinate of this test point in the mechanical arm coordinate system.

4. mechanical arm motion control method as claimed in claim 1 is characterized in that, this method also comprises step: judge according to the layout information in the cloth map file whether PCB to be measured also has other test point not test; If also have other test point not test, then control initial point (X0, Y0 that mechanical arm is repositioned onto probe the mechanical arm coordinate system; Z0); And return step (e), and all to test up to all test points of PCB to be measured and finish, flow process finishes.

5. mechanical arm motion control method as claimed in claim 1; It is characterized in that; The information of said part to be measured and test point information comprise: the type of part to be measured; The quantity of all kinds part to be measured, the test point that comprises on the dimension information of each part to be measured and each part to be measured, each test point two-dimensional coordinate and the dimension information of each test point in PCB coordinate system to be measured.

6. mechanical arm kinetic control system; Run on the control computer; This control computer expert crosses data wire and is connected with mechanical arm, image capture unit, radium-shine rangefinder and tester respectively; Mechanical arm utilizes the probe grabbing device to grasp the probe of tester, it is characterized in that this system comprises:

Information reading module is used to read the cloth map file of PCB to be measured, obtains the layout information of PCB to be measured, comprise PCB coordinate system to be measured origin (x0, y0), the information of part to be measured and test point information;

Control module, be used for according to PCB coordinate system to be measured origin (x0 y0) produces first control instruction, control mechanical arm traveling probe to PCB coordinate origin to be measured (x0, y0) directly over;

The coordinate determination module, be used for according to PCB coordinate system to be measured origin (x0, y0) and the probe that obtains of radium-shine stadia surveying and PCB to be measured apart from Z0 confirm the mechanical arm coordinate system origin (X0, Y0, Z0);

Information reading module also is used to read the two-dimensional coordinate of the last test point of PCB to be measured;

Computing module is used to calculate the relative displacement value of this test point and PCB coordinate origin to be measured;

Control module also is used for producing second control instruction according to the relative displacement value that calculates, and the control mechanical arm is done corresponding displacement in the mechanical arm coordinate system;

The Figure recognition module is used for confirming at the current image of the PCB to be measured of image capture unit acquisition according to the layout information of PCB to be measured the geometric figure of this test point;

Computing module; Also be used for calculating at the geometrical center point of current this test point of image and the pixel value difference of current image center point, and convert pixel value difference the displacement correction amount of mechanical arm in the mechanical arm coordinate system into according to the scaling of current image and PCB to be measured;

Control module; Also be used for giving birth to the 3rd control instruction according to the displacement correction volume production that calculates; Corresponding correction is done in displacement in the mechanical arm coordinate system to mechanical arm; And the probe that obtains according to radium-shine stadia surveying and the current distance Zn of this test point on the PCB to be measured produce the 4th control instruction, and the control mechanical arm moves negative Zn along Z-direction, so that probe accurately navigates to this test point on the PCB to be measured.

7. mechanical arm kinetic control system as claimed in claim 6 is characterized in that, in the process of mechanical arm motion, the probe that mechanical arm grasps is positioned at the dead ahead of the optical center point of image capture unit all the time.

8. mechanical arm kinetic control system as claimed in claim 6; It is characterized in that said coordinate determination module also is used for confirming the coordinate of this test point in the mechanical arm coordinate system according to the distance of this test point this test point on the coordinate of PCB coordinate system to be measured, the displacement correction amount that calculates and probe and PCB to be measured.

9. mechanical arm kinetic control system as claimed in claim 6; It is characterized in that; Said information reading module also is used for judging according to the layout information of cloth map file whether PCB to be measured also has other test point not test; If also have other test point not test, after then control module produced the 5th control instruction control mechanical arm probe is repositioned onto the initial point of mechanical arm coordinate system, the control mechanical arm navigated to probe the next test point of PCB to be measured.

10. mechanical arm kinetic control system as claimed in claim 6; It is characterized in that; The information of said part to be measured and test point information comprise: the type of part to be measured; The quantity of all kinds part to be measured, the test point that comprises on the dimension information of each part to be measured and each part to be measured, each test point two-dimensional coordinate and the dimension information of each test point in PCB coordinate system to be measured.

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