CN102794771A - Mechanical arm correction system and method - Google Patents

Abstract

A mechanical arm calibration system and method, the system is used to: obtain calibration parameters; control the movement of the mechanical arm to obtain the center a of the first image plane; control the movement of the mechanical arm according to the distance between the first object to be measured and the second object to be measured , get the center b of the second image plane; calculate the vector A from the center a of the first image plane to the center b of the second image plane, and calculate the correction angle φ according to the vector A and vector Z; adjust the flange of the mechanical arm according to the correction angle φ A surface axis vector Z, such that the flange surface axis vector Z of the mechanical arm is perpendicular to the plane where the first object to be measured and the second object to be measured are located. The invention can automatically correct the mechanical arm.

Description

Calibration system and method for mechanical arm

technical field

The invention relates to a testing system and method, in particular to a mechanical arm calibration system and method.

Background technique

With the development of electronic science and technology, printed circuit boards (Printed Circuit Board, PCB) have become an indispensable and important part of various electrical equipment (such as computers). Since ultra-high frequency microwave signals are transmitted in the circuit of the printed circuit board, in order to ensure the reliability of the printed circuit board in use, it is necessary to detect the physical characteristics (such as impedance) of its parts when leaving the factory.

With the continuous improvement of the design of the mechanical arm, some test systems can now use the mechanical arm to automatically test the physical characteristics of the parts on the printed circuit board. However, the current systems that use robotic arms for automated testing cannot correct the robotic arm, resulting in inaccurate measurement results.

Contents of the invention

In view of the above, it is necessary to provide a mechanical arm calibration system, which can automatically calibrate the mechanical arm so that the axis vector of the flange surface of the mechanical arm is perpendicular to the plane of the object to be measured.

In view of the above, it is also necessary to provide a calibration method for the mechanical arm, which can automatically correct the mechanical arm so that the axis vector of the flange surface of the mechanical arm is perpendicular to the plane of the object to be measured.

A mechanical arm correction system, running in a main control computer, the main control computer controls the mechanical arm through a mechanical arm motion control system, the system includes:

The parameter acquisition module is used to acquire the image distance H of the image capture device of the mechanical arm, the axial center vector Z of the flange surface of the mechanical arm, and the distance L between the first object to be measured and the second object to be measured;

The first image plane center acquisition module is used to control the movement of the mechanical arm to optimize the image clarity of the first object to be measured captured by the image capture device, and obtain the current image plane center of the image capture device, which is recorded as the first image plane center a;

The second image plane center acquisition module is used to control the movement of the mechanical arm according to the distance L between the first object to be measured and the second object to be measured, so as to optimize the image definition of the second object to be measured captured by the image capture device, And obtain the current image plane center of the image capture device, denoted as the second image plane center b;

The correction angle calculation module is used to calculate the vector A from the center a of the first image plane to the center b of the second image plane, and calculate the correction angle φ according to the vector A and the vector Z; and

The mechanical arm adjustment module is used to adjust the axis vector Z of the flange surface of the mechanical arm according to the correction angle φ, so that the axis vector Z of the flange surface of the mechanical arm is perpendicular to the position where the first object to be measured and the second object to be measured are located. flat.

A method for calibrating a mechanical arm is applied to a main control computer, the main control computer controls the mechanical arm through a mechanical arm motion control system, and the method includes the following steps:

The parameter acquisition step is to obtain the image distance H of the image capture device of the mechanical arm, the axial center vector Z of the flange surface of the mechanical arm, and the distance L between the first object to be measured and the second object to be measured;

The step of obtaining the center of the first image plane is to control the movement of the mechanical arm to optimize the image clarity of the first object to be measured captured by the image capture device, and obtain the current center of the image plane of the image capture device, which is recorded as the center of the first image plane a;

The step of obtaining the center of the second image plane is to control the movement of the mechanical arm according to the distance L between the first object to be measured and the second object to be measured, so as to optimize the image definition of the second object to be measured captured by the image capture device, and obtain The current image plane center of the image capture device is denoted as the second image plane center b;

The correction angle calculation step is to calculate the vector A from the center a of the first image plane to the center b of the second image plane, and calculate the correction angle φ according to the vector A and the vector Z; and

The step of adjusting the mechanical arm is to adjust the axial vector Z of the flange surface of the mechanical arm according to the correction angle φ, so that the axial vector Z of the flange surface of the mechanical arm is perpendicular to the plane where the first object to be measured and the second object to be measured are located.

The aforementioned methods may be performed by an electronic device, wherein the electronic device has attached one or more processors, memory, and one or more modules, programs or instruction sets stored in the memory for performing the methods. In some embodiments, the electronic device provides multiple functions including wireless communication.

Instructions for performing the foregoing methods may be embodied in a computer program product configured to be executed by one or more processors.

Compared with the prior art, the manipulator calibration system and method can automatically calibrate the manipulator so that the axis vector of the flange surface of the manipulator is perpendicular to the plane of the object to be measured, avoiding the occurrence of positioning errors of the manipulator , improving the accuracy of the test.

Description of drawings

FIG. 1 is a hardware architecture diagram of a preferred embodiment of the robotic arm calibration system of the present invention.

Fig. 2 is a schematic structural diagram of the main control computer in Fig. 1 .

FIG. 3 is a functional block diagram of the manipulator calibration system shown in FIG. 1 .

FIG. 4A and FIG. 4B are flow charts of a preferred embodiment of the method for calibrating the robotic arm of the present invention.

FIG. 5 is a plan view of the positional relationship between the image plane of the image capture device and the device under test.

6 is a perspective view of the positional relationship between the image plane of the image capturing device and the device under test.

Description of main component symbols

Main computer 20   Robotic arm correction system twenty one display screen twenty two memory twenty three input device twenty four Processor 25   Robotic arm motion control system 31   Robotic arm control channel 32

Mechanical arm 33 Fixtures 34 Digital image capture control system 41 Digital image capture control channel 42 Image capture device 43 A printed circuit board 60 Test machine 70 Parameter acquisition module 201 The first image plane center acquisition module 202 The second image plane center acquisition module 203 Correction angle calculation module 204   Robotic arm adjustment module 205

The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings.

Detailed ways

As shown in FIG. 1 , it is a system architecture diagram of a preferred embodiment of the manipulator calibration system of the present invention. The manipulator calibration system 21 runs in the main control computer 20 . Wherein, the main control computer 20 is connected with the mechanical arm motion control system 31 and the digital image capturing control system 41 . The robot arm motion control system 31 controls the robot arm 33 through the robot arm control channel 32 , and the digital image capture control system 41 controls the image capture device 43 through the digital image capture control channel 42 . The image capture device 43 is installed on the robot arm 33 through the fixing device 34 . Wherein, the robotic arm 33 may be an articulated or non-articulated robotic arm.

In this embodiment, the manipulator control channel 32 and the digital image capture control channel 42 may be communication cables, and the fixing device 34 is installed in the flange-face composite base in front of the manipulator 33 . The image capture device 43 may be a digital camera, and is used to capture the image of the object under test on the printed circuit board 60 , and the printed circuit board 60 is placed on the testing machine 70 . It can be understood that in other embodiments, the printed circuit board 60 can also be replaced by other electronic devices.

Referring to FIG. 2 , the main control computer 20 includes a robotic arm calibration system 21 , a display device 22 , a memory 23 , an input device 24 and a processor 25 connected through a data bus.

The memory 23 is used to store data such as program codes of the manipulator calibration system 21 . The display device 22 and the input device 24 are used as input and output devices of the host computer 20 .

The manipulator calibration system 21 is used to automatically calibrate the manipulator 33 so that the axis vector of the flange surface of the manipulator 33 is perpendicular to the plane of the object to be measured. The specific process is described below.

In this embodiment, the manipulator calibration system 21 can be divided into one or more modules, and the one or more modules are stored in the memory 23 and configured to be controlled by one or more processors ( This embodiment is executed by one processor 25) to complete the present invention. For example, as shown in FIG. 3 , the manipulator calibration system 21 is divided into a parameter acquisition module 201, a first image plane center acquisition module 202, a second image plane center acquisition module 203, a correction angle calculation module 204, and a manipulator adjustment module. Module 205. The module referred to in the present invention is a program segment that completes a specific function, and is more suitable than a program to describe the execution process of the software in the main control computer 20. The functions of each module will be described below in conjunction with the flow chart of FIG. 4 .

As shown in FIG. 4A and FIG. 4B , it is a flow chart of a preferred embodiment of the method for calibrating a manipulator of the present invention.

Step S10 , the parameter acquiring module 201 acquires the image distance H of the image capture device 43 , the axial center vector Z of the flange surface of the robot arm 33 , and the distance L between the first object under test and the second object under test on the printed circuit board 60 . Wherein, the image distance H refers to the distance between the image and the lens center of the image capturing device 43 . Referring to FIG. 5 and FIG. 6 , p1 represents the first test object, and p2 represents the second generation test object.

Step S11 , keeping the vector Z unchanged, the first image plane center acquisition module 202 controls the movement of the robotic arm 33 so that the first object p1 to be measured enters the image plane of the image capturing device 43 . In this embodiment, the image capturing device 43 captures a shallow depth of field (Shallow Depth of Field) image of the first object under test p1. In other embodiments, the image capture device 43 can also capture other images of the first object p1 to be tested, such as a Large Depth of Field image.

Step S12, the first image plane center acquisition module 202 adjusts the mechanical arm 33 so that the first object p1 to be measured is located within the depth of field of the image capturing device 43, and performs a contrast histogram statistical analysis on the image captured by the image capturing device 43 so that the first object to be measured is Optimizing the image clarity of the object p1. Among them, contrast refers to the ratio of black and white in the picture, that is, the gradient level from black to white. The larger the ratio, the more levels of gradation from black to white, and the richer the color expression. The impact of contrast on visual effects is very important. Generally speaking, the greater the contrast, the clearer and more eye-catching the image, and the brighter the color; while the lower the contrast, the whole picture will be gray.

Step S13 , the first image plane center acquisition module 202 performs contour edge analysis on the first object p1 to be measured, and obtains the image area center p of the first object p1 to be measured (refer to FIG. 5 and FIG. 6 ).

Step S14 , the first image plane center acquisition module 202 moves the robotic arm 33 according to the image plane direction of the image capture device 43 , so that the image area center p of the first object p1 to be measured coincides with the image plane center of the image capture device 43 .

Step S15, the first image plane center acquisition module 202 adjusts the robotic arm 33, and once again performs a contrast histogram statistical analysis on the image captured by the image capture device 43 to optimize the image definition of the first object p1 to be measured, and acquires the image The current image plane center of the capturing device 43 is recorded as the first image plane center a (refer to FIG. 5 and FIG. 6 ).

In step S16 , the first image plane center acquisition module 202 stores the position coordinates of the first image plane center a and the image file of the first object under test p1 to the memory 23 .

Step S17, keeping the vector Z unchanged, the second image plane center acquisition module 203 controls the movement of the mechanical arm 33 according to the distance L between the first object to be measured p1 and the second object to be measured p2, so that the second object to be measured p2 enters the image within the image plane of the capturing device 43 . In this embodiment, the image capturing device 43 captures a shallow depth of field (Shallow Depth of Field) image of the second object to be measured p2. In other embodiments, the image capture device 43 can also capture other images of the second object p2 to be measured, such as a Large Depth of Field image.

Step S18, the second image plane center acquisition module 203 adjusts the mechanical arm 33 so that the second object p2 to be measured is located within the depth of field of the image capturing device 43, and performs a contrast histogram statistical analysis on the image captured by the image capturing device 43 so that the second object to be measured p2 Optimizing the image clarity of the object p2.

Step S19 , the second image plane center acquisition module 203 performs contour edge analysis on the second object p2 to be measured, and obtains the image area center q of the second object p2 to be measured (refer to FIG. 5 and FIG. 6 ).

Step S20 , the second image plane center acquisition module 203 moves the robotic arm 33 according to the image plane direction of the image capture device 43 , so that the image area center q of the second object p2 to be measured coincides with the image plane center of the image capture device 43 .

Step S21, the second image plane center acquisition module 203 adjusts the robotic arm 33, and once again performs a contrast histogram statistical analysis on the image captured by the image capture device 43 to optimize the image definition of the second object p2 to be measured, and acquires the image The current image plane center of the capturing device 43 is recorded as the second image plane center b (refer to FIG. 5 and FIG. 6 ).

Step S22 , the second image plane center acquisition module 203 stores the position coordinates of the second image plane center b and the image file of the second object under test p2 to the memory 23 .

In step S23 , the correction angle calculation module 204 calculates a vector A from the center a of the first image plane to the center b of the second image plane (refer to FIG. 5 ).

Step S24 , the correction angle calculation module 204 calculates the correction angle φ according to the vector A and the vector Z, wherein the correction angle φ is equal to 90 degrees minus the angle between the vector A and the vector Z (see FIG. 5 ).

In step S25, the mechanical arm adjustment module 205 adjusts the axial center vector Z of the flange surface of the mechanical arm 33 according to the correction angle φ, so that the axial center vector Z of the flange surface of the mechanical arm 33 is perpendicular to the first object to be measured p1 and the second object to be measured. Measure the plane where the object p2 is located. In this embodiment, the plane where the first DUT p1 and the second DUT p2 are located is the plane of the printed circuit board 60 .

Specifically, the mechanical arm adjustment module 205 rotates the axis vector Z of the flange surface of the mechanical arm 33 clockwise to correct the angle φ, so that the vector Z is parallel to the plane where the first object p1 and the second object p2 are located. vector N, so that the axis vector Z of the flange surface of the mechanical arm 33 is perpendicular to the plane where the first object p1 and the second object p2 are located.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be Modifications or equivalent replacements can be made without departing from the spirit and scope of the technical solutions of the present invention.

Claims (10)

1. A mechanical arm calibration system runs in a main control computer, and the main control computer controls the mechanical arm through a mechanical arm motion control system. It is characterized in that the system includes: The parameter acquisition module is used to acquire the image distance H of the image capture device of the mechanical arm, the axial center vector Z of the flange surface of the mechanical arm, and the distance L between the first object to be measured and the second object to be measured; The first image plane center acquisition module is used to control the movement of the mechanical arm to optimize the image clarity of the first object to be measured captured by the image capture device, and obtain the current image plane center of the image capture device, which is recorded as the first image plane center a; The second image plane center acquisition module is used to control the movement of the mechanical arm according to the distance L between the first object to be measured and the second object to be measured, so as to optimize the image definition of the second object to be measured captured by the image capture device, And obtain the current image plane center of the image capture device, denoted as the second image plane center b; The correction angle calculation module is used to calculate the vector A from the center a of the first image plane to the center b of the second image plane, and calculate the correction angle φ according to the vector A and the vector Z; and The mechanical arm adjustment module is used to adjust the axis vector Z of the flange surface of the mechanical arm according to the correction angle φ, so that the axis vector Z of the flange surface of the mechanical arm is perpendicular to the position where the first object to be measured and the second object to be measured are located. flat. 2. The robotic arm calibration system according to claim 1, wherein the first image plane center acquisition module acquiring the first image plane center a comprises: Keeping the vector Z unchanged, controlling the movement of the mechanical arm so that the first object to be measured enters the image plane of the image capture device; adjusting the mechanical arm so that the first object to be measured is located within the depth of field of the image capturing device, and performing contrast histogram statistical analysis on the image captured by the image capturing device, so as to optimize the image definition of the first object to be measured; Perform contour edge analysis on the first object to be measured to obtain the image area center of the first object to be measured; moving the robotic arm according to the direction of the image plane of the image capture device, so that the center of the image area of the first object to be measured coincides with the center of the image plane of the image capture device; Adjust the robotic arm, and perform contrast histogram statistical analysis on the image captured by the image capture device again, so as to optimize the image clarity of the first object to be tested, and obtain the current image plane center of the image capture device, which is recorded as the first image plane center a; and The position coordinates of the center a of the first image plane and the image file of the first object under test are stored in the memory of the main control computer. 3. The robotic arm calibration system according to claim 1, wherein the second image plane center acquisition module acquiring the second image plane center b comprises: Keeping the vector Z unchanged, controlling the movement of the mechanical arm according to the distance L between the first object to be measured and the second object to be measured, so that the second object to be measured enters the image plane of the image capture device; adjusting the mechanical arm so that the second object to be measured is located within the depth of field of the image capturing device, and performing a statistical analysis of the contrast histogram on the image captured by the image capturing device, so as to optimize the image definition of the second object to be measured; Perform contour edge analysis on the second object to be measured to obtain the center of the image area of the second object to be measured; moving the robotic arm according to the direction of the image plane of the image capture device, so that the center of the image area of the second object to be measured coincides with the center of the image plane of the image capture device; Adjust the mechanical arm, and once again perform a statistical analysis of the contrast histogram on the image captured by the image capture device, so as to optimize the image clarity of the second object to be measured, and obtain the current image plane center of the image capture device, which is recorded as the second image plane center b; and The position coordinates of the center b of the second image plane and the image file of the second object to be measured are stored in the memory of the main control computer. 4. The robotic arm calibration system according to claim 1, wherein the calibration angle φ is equal to 90 degrees minus the angle between vector A and vector Z. 5. The manipulator correction system according to claim 1, wherein the manipulator adjustment module adjusts the flange surface axis vector Z of the manipulator according to the correction angle φ, comprising: The heart vector Z rotates clockwise to correct the angle φ, so that the vector Z is parallel to the normal vector N of the plane where the first object to be measured and the second object to be measured are located, so that the axis vector Z of the flange surface of the mechanical arm is perpendicular to the first object to be measured The plane where the object to be measured and the second object to be measured are located. 6. A method for calibrating a mechanical arm is applied in a main control computer, and the main control computer controls the mechanical arm through a mechanical arm motion control system. It is characterized in that the method comprises the following steps: The parameter acquisition step is to obtain the image distance H of the image capture device of the mechanical arm, the axial center vector Z of the flange surface of the mechanical arm, and the distance L between the first object to be measured and the second object to be measured; The step of obtaining the center of the first image plane is to control the movement of the mechanical arm to optimize the image clarity of the first object to be measured captured by the image capture device, and obtain the current center of the image plane of the image capture device, which is recorded as the center of the first image plane a; The step of obtaining the center of the second image plane is to control the movement of the mechanical arm according to the distance L between the first object to be measured and the second object to be measured, so as to optimize the image definition of the second object to be measured captured by the image capture device, and obtain The current image plane center of the image capture device is denoted as the second image plane center b; The correction angle calculation step is to calculate the vector A from the center a of the first image plane to the center b of the second image plane, and calculate the correction angle φ according to the vector A and the vector Z; and The step of adjusting the mechanical arm is to adjust the axial vector Z of the flange surface of the mechanical arm according to the correction angle φ, so that the axial vector Z of the flange surface of the mechanical arm is perpendicular to the plane where the first object to be measured and the second object to be measured are located. 7. The mechanical arm calibration method according to claim 6, wherein the step of obtaining the center of the first image plane comprises: Keeping the vector Z unchanged, controlling the movement of the mechanical arm so that the first object to be measured enters the image plane of the image capture device; adjusting the mechanical arm so that the first object to be measured is located within the depth of field of the image capturing device, and performing contrast histogram statistical analysis on the image captured by the image capturing device, so as to optimize the image definition of the first object to be measured; Perform contour edge analysis on the first object to be measured to obtain the image area center of the first object to be measured; moving the robotic arm according to the direction of the image plane of the image capture device, so that the center of the image area of the first object to be measured coincides with the center of the image plane of the image capture device; Adjust the robotic arm, and perform contrast histogram statistical analysis on the image captured by the image capture device again, so as to optimize the image clarity of the first object to be tested, and obtain the current image plane center of the image capture device, which is recorded as the first image plane center a; and The position coordinates of the center a of the first image plane and the image file of the first object under test are stored in the memory of the main control computer. 8. The method for calibrating a mechanical arm according to claim 6, wherein the step of obtaining the center of the second image plane comprises: Keeping the vector Z unchanged, controlling the movement of the mechanical arm according to the distance L between the first object to be measured and the second object to be measured, so that the second object to be measured enters the image plane of the image capture device; adjusting the mechanical arm so that the second object to be measured is located within the depth of field of the image capturing device, and performing a statistical analysis of the contrast histogram on the image captured by the image capturing device, so as to optimize the image definition of the second object to be measured; Perform contour edge analysis on the second object to be measured to obtain the center of the image area of the second object to be measured; moving the robotic arm according to the direction of the image plane of the image capture device, so that the center of the image area of the second object to be measured coincides with the center of the image plane of the image capture device; Adjust the mechanical arm, and once again perform a statistical analysis of the contrast histogram on the image captured by the image capture device, so as to optimize the image clarity of the second object to be measured, and obtain the current image plane center of the image capture device, which is recorded as the second image plane center b; and The position coordinates of the center b of the second image plane and the image file of the second object to be measured are stored in the memory of the main control computer. 9. The method for calibrating a robotic arm according to claim 6, wherein the calibration angle φ is equal to 90 degrees minus the angle between vector A and vector Z. 10. The method for correcting a mechanical arm according to claim 6, wherein the step of adjusting the mechanical arm comprises: rotating the axial center vector Z of the flange surface of the mechanical arm clockwise to correct the angle φ, so that the vector Z is parallel to the first The normal vector N of the plane where the first object to be measured and the second object to be measured are located, so that the axial center vector Z of the flange surface of the mechanical arm is perpendicular to the plane where the first object to be measured and the second object to be measured are located.

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