Motion error compensation system based on dynamic segmentation visual servo
Through the motion error compensation system of dynamic segmented visual servo, mechanical deviations are calculated and compensated in segments in real time, which solves the problem of insufficient adaptability of dynamic changes of mechanical systems in traditional methods and improves the motion precision and position accuracy of placement equipment.
Patent Information
- Application Number
- CN202510944534.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-09
- Publication Date
- 2025-09-12
AI Technical Summary
Traditional motion compensation methods are based on static data calibration and are difficult to adapt to the dynamic changes of mechanical systems in real time, resulting in a decrease in the accuracy of placement equipment.
A motion error compensation system based on dynamic segmented visual servoing is adopted, which includes a drive module, a fine-tuning compensation module and a secondary verification module. The mechanical deviation is calculated in real time through the visual measurement unit and segmented compensation is performed, and the control amount is dynamically adjusted to improve accuracy.
It significantly improves the motion control accuracy of the placement equipment, reduces the possibility of placement deviation, and can effectively capture local mechanical defects and avoid error transmission.
Smart Images
Figure CN120640674A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of visual image processing, and in particular to a motion error compensation system based on dynamic segmented visual servoing. Background Art
[0002] In modern electronics manufacturing, pick-and-place machines (P&P machines) are core production equipment, widely used in applications such as printed circuit board (PCB) assembly, semiconductor packaging, and microelectronic component placement. These machines typically rely on servo motors to drive precision guide rails for planar motion. However, due to the limitations of machining and assembly, these guide rails can be subject to linearity errors, backlash, and wear, resulting in reduced accuracy.
[0003] However, the traditional motion compensation method is based on static data calibration, which makes it difficult to adapt to the dynamic changes of the mechanical system in real time, resulting in limited compensation effect and thus causing placement deviation. Summary of the Invention
[0004] In view of the deficiencies in the prior art, the present invention provides a motion error compensation system based on dynamic segmented visual servoing, which solves the technical problems in the above-mentioned background technology.
[0005] To achieve the above object, the present invention provides the following technical solutions: A motion error compensation system based on dynamic segmented visual servoing, comprising: a driving module, a fine-tuning compensation module and a secondary verification module; The driving module is used to control the placement equipment to move in a plane; The fine-tuning compensation module includes an initial control unit, a visual measurement unit and a compensation unit; The initial control unit is used to control the driving module according to the instruction to drive the placement device to move to the target point C, and mark the final stop position of the placement device as the calibration point A; the visual measurement unit is used to calculate the plane coordinates of the calibration point A based on the first image information obtained by the visual module The actual distance between the calibration point A and the target point C The compensation unit is used to calculate the actual distance The control drive module drives the placement equipment to move from the calibration point A to the target point C; The secondary verification module is used to determine whether the placement device is at the target point C based on the second image information obtained by the vision module. If so, the process ends; if not, the position of the placement device is used as the calibration point A and returned to the vision measurement unit.
[0006] Furthermore, in the visual measurement unit, the following steps are specifically included: S11. Take the initial position of the placement equipment as the origin 0, and use the horizontal and vertical guide rails as the x-axis and y-axis to construct a plane coordinate system. Mark the plane coordinate of the target point C in the plane coordinate system. ; S12: Use a visual module to photograph the target point C and the calibration point A to obtain first image information; S13: Calculate the actual distance between the target point C and the calibration point A based on the first image information. .
[0007] Furthermore, in step S13, the following steps are specifically included: S131, using the center point of the first image information as the origin 0, and constructing an image coordinate system with the horizontal and vertical axes of the first image information being u and v, respectively; S132: Extract the pixel coordinates of the correction point A in the image coordinate system. ; S133, calculate the lateral mechanical deviation compensation and longitudinal mechanical deviation compensation ; S134, according to the lateral mechanical deviation compensation and longitudinal mechanical deviation compensation The pixel coordinates of the correction point A Convert the plane coordinates of the correction point A to the plane coordinate system ; S135, according to the plane coordinates of calibration point A Calculate actual distance , and its calculation formula is: , Where, Indicates the actual distance between calibration point A and target point C.
[0008] Furthermore, in step S133, the following steps are specifically included: S1331, in the actual path of the placement device moving from origin 0 to calibration point A, the actual path is evenly divided into n first sub-paths, each of which has a length of ; S1332: Connect the origin 0 and the target point C in the plane coordinate system to generate an ideal path, and evenly divide the ideal path into n second sub-paths, each of which has a length of ; S1333. Extract the end point coordinates of each first subpath and the end point coordinates of the second subpath , and calculate the first deviation , and its calculation formula is: , in, , , in, express function; represents the direction angle of the second subpath; ; S1334, according to the first deviation Calculate the lateral mechanical deviation compensation of the kth first subpath and longitudinal mechanical deviation compensation ; S1335: Repeat steps S1333-S1334 until the end point, and output the lateral mechanical deviation compensation amount. and longitudinal mechanical deviation compensation .
[0009] Furthermore, in step S1334, the lateral mechanical deviation compensation amount and longitudinal mechanical deviation compensation The calculation formula is: , Where, Represents the learning rate.
[0010] Furthermore, in step S134, the plane coordinates of point A are corrected. The conversion formula is: , Where, and Respectively represent the conversion coefficients of pixels on the u-axis and v-axis to physical coordinates; Indicates the origin coordinates of the image coordinate system.
[0011] Furthermore, in the compensation unit, the following steps are specifically included: S21, according to the plane coordinates of calibration point A and the plane coordinates of the target point C Construct the target line segment AC and calculate its azimuth , and its calculation formula is: , S22, the driving module controls the placement device to move along the target line segment AC, and the vision module acquires the second image information at a fixed frequency; S23, extract the current real-time position P of the placement device, and extract the plane coordinates of point P in the plane coordinate system ; S24, according to the azimuth Calculate the ideal plane coordinates of point P , and its calculation formula is: , Where, Indicates the actual moving distance of the placement equipment; S25, according to the ideal plane coordinates Calculate the second deviation , and its calculation formula is: , S26, according to the second deviation Calculate the superposition compensation amount ; S27, according to the superposition compensation amount Compensate for the motion of the drive module.
[0012] Furthermore, in step S26, the compensation amount is superimposed The calculation formula is: , Where, 、 and Respectively represent PID parameters; in, , , , Where, represents the critical oscillation period; Indicates the time required for the motor response to reach 63.2% of its steady-state value.
[0013] Compared with the prior art, the present invention provides a motion error compensation system based on dynamic segmented visual servoing, which has the following beneficial effects: 1. The present invention divides the path into several uniform small segments, and independently calculates the mechanical deviation compensation amount for each segment, which can capture local mechanical defects such as guide rail bending and backlash. In addition, the error of each segment only affects the current segment and will not be transmitted to subsequent segments, which can significantly improve the compensation accuracy of nonlinear errors.
[0014] 2. The present invention measures the deviation between the actual position and the target position in real time through visual servoing, dynamically adjusts the control amount, and adopts segmented compensation to avoid global error transmission, which can effectively improve the control accuracy of the placement equipment movement and reduce the possibility of placement offset. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings: Figure 1 Schematic diagram of a motion error compensation system based on dynamic segmented visual servoing of the present invention. DETAILED DESCRIPTION
[0016] To make the above-mentioned objectives, features, and advantages of the present invention more clearly understood, the present invention is further described below in detail with reference to the accompanying drawings and specific embodiments. This will enable a full understanding of how this application uses technical means to solve technical problems and achieve technical effects, and to implement the invention accordingly.
[0017] Those skilled in the art will appreciate that all or part of the steps in the following embodiments can be accomplished by instructing related hardware through a program. Therefore, the present application may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.
[0018] Placement equipment is a core device in electronics manufacturing, used to accurately place electronic components (such as chips, resistors, capacitors, etc.) on circuit boards. Its core task is to complete component positioning and placement with high precision and efficiency, which directly affects the performance and yield of electronic products. Conventional placement equipment relies on the inherent precision of mechanical guides and servo motors. It is limited by the deviation between theoretical coordinates and actual position caused by mechanical defects such as guide straightness and backlash, as well as multiple positioning fluctuations caused by random factors such as motor control and vibration. Therefore, this paper proposes a motion error compensation system based on dynamic segmented visual servoing, which includes: a drive module, a fine-tuning compensation module, and a secondary verification module. The driving module is used to control the movement of the placement equipment in a plane; specifically, the driving module is based on a servo motor and an ultra-precision motor; it should be noted that the workbench of a common placement equipment is a rectangle, and horizontal and vertical guide rails are respectively set in the horizontal and vertical directions of the workbench. When controlling the movement of the placement equipment, the servo motor drives the horizontal and vertical guide rails to move.
[0019] The fine-tuning compensation module includes an initial control unit, a visual measurement unit and a compensation unit; The initial control unit is used to control the driving module according to the instruction to drive the placement device to move to the target point C, and mark the final stop position of the placement device as the calibration point A; The visual measurement unit is used to calculate the plane coordinates of the calibration point A based on the first image information obtained by the visual module The actual distance between the calibration point A and the target point C Specifically, due to mechanical defects such as the straightness and backlash of the mechanical guide rail, there will be a deviation between the theoretical coordinates and the actual position. In addition, due to the long-term operation of the placement equipment or in a temperature-changing environment, the equipment will produce time-varying errors due to thermal expansion, mechanical wear, etc., which will lead to a decrease in the accuracy of the mechanical guide rail. Therefore, in the visual measurement unit, the following steps are specifically included: S11. Take the initial position of the placement equipment as the origin 0, and use the horizontal and vertical guide rails as the x-axis and y-axis to construct a plane coordinate system. Mark the plane coordinate of the target point C in the plane coordinate system. ; S12, using a visual module to shoot the target point C and the calibration point A to obtain first image information; in the present invention, the visual module is constructed based on a high-definition camera, and the high-definition camera is set on the mounting equipment; S13: Calculate the actual distance between the target point C and the calibration point A based on the first image information. Specifically, in step S13, the following steps are specifically included: S131. Using the center point of the first image information as the origin 0, and constructing an image coordinate system with the horizontal and vertical axes of the first image information being u-axis and v-axis, respectively; specifically, the u-axis and v-axis are the horizontal and vertical axes in the image coordinates; S132: Extract the pixel coordinates of the correction point A in the image coordinate system. ; S133, calculate the lateral mechanical deviation compensation and longitudinal mechanical deviation compensation Specifically, due to the deviation between the theoretical coordinates and the actual position caused by mechanical defects such as the straightness of the guide rail and backlash, as well as time-varying errors caused by thermal expansion and mechanical wear of the equipment during long-term operation or in a temperature-varying environment, the accuracy of the mechanical guide rail decreases. Therefore, step S133 specifically includes the following steps: S1331, in the actual path of the placement device moving from origin 0 to calibration point A, the actual path is evenly divided into n first sub-paths, each of which has a length of ; S1332: Connect the origin 0 and the target point C in the plane coordinate system to generate an ideal path, and evenly divide the ideal path into n second sub-paths, each of which has a length of ; Specifically, ; S1333. Extract the end point coordinates of each first subpath and the end point coordinates of the second subpath , and calculate the first deviation , and its calculation formula is: , in, , , in, express function; represents the direction angle of the second subpath; ; S1334, according to the first deviation Calculate the lateral mechanical deviation compensation of the kth first subpath and longitudinal mechanical deviation compensation Specifically, in step S1334, the lateral mechanical deviation compensation amount and longitudinal mechanical deviation compensation The calculation formula is: , Where, represents the learning rate; in the present invention, is 0.5; S1335: Repeat steps S1333-S1334 until the end point, and output the lateral mechanical deviation compensation amount. and longitudinal mechanical deviation compensation .
[0020] S134, according to the lateral mechanical deviation compensation and longitudinal mechanical deviation compensation The pixel coordinates of the correction point A Convert the plane coordinates of the correction point A to the plane coordinate system Specifically, in step S134, the plane coordinates of point A are corrected The conversion formula is: , Where, and Respectively represent the conversion coefficients of pixels on the u-axis and v-axis to physical coordinates; Represents the origin coordinates of the image coordinate system; S135, according to the plane coordinates of calibration point A Calculate actual distance , and its calculation formula is: , Where, Indicates the actual distance between calibration point A and target point C.
[0021] Since the common method of calculating the global fixed mechanical deviation compensation amount cannot compensate for nonlinear errors (such as local bending of the guide rail), and also ignores the problem of dynamic disturbances such as vibration and thermal deformation that lead to reduced real-time accuracy, as well as the long-distance cumulative error in which the error increases significantly with the increase of movement distance, the present invention divides the path into several uniform small segments, and independently calculates the mechanical deviation compensation amount for each segment, which can capture local mechanical defects (such as guide rail bending and backlash). In addition, the error of each segment only affects the current segment and will not be transmitted to subsequent segments, which can significantly improve the compensation accuracy of nonlinear errors.
[0022] The compensation unit is used to adjust the actual distance The control drive module drives the placement device to move from the calibration point A to the target point C. Specifically, the compensation unit controls the ultra-precision motor to drive the placement device to move to the target point C. It should be noted that the ultra-precision motor is used only when the compensation unit controls the placement device to move, and the servo motor is used for other purposes. In addition, since vibration still occurs when the ultra-precision motor drives the placement device to move, errors may occur, which may make it difficult for the placement device to accurately move to the target point C. Therefore, the compensation unit specifically includes the following steps: S21, according to the plane coordinates of calibration point A and the plane coordinates of the target point C Construct the target line segment AC and calculate its azimuth , and its calculation formula is: , S22, the driving module controls the placement device to move along the target line segment AC, and the vision module acquires the second image information at a fixed frequency; S23, extract the current real-time position P of the placement device, and extract the plane coordinates of point P in the plane coordinate system ; S24, according to the azimuth Calculate the ideal plane coordinates of point P , and its calculation formula is: , Where, Indicates the actual moving distance of the placement equipment; in the present invention, Through the plane coordinates of point P And the plane coordinates of the correction point A calculate; S25, according to the ideal plane coordinates Calculate the second deviation , and its calculation formula is: , S26, according to the second deviation Calculate the superposition compensation amount Specifically, in step S26, the compensation amount is superimposed The calculation formula is: , Where, 、 and Respectively represent PID parameters; in, , , , Where, represents the critical oscillation period; Indicates the time required for the motor response to reach 63.2% of its steady-state value.
[0023] S27, according to the superposition compensation amount Compensate for the motion of the drive module.
[0024] Common drive devices control the movement compensation of placement equipment from the calibration point to the target point and rely on fixed compensation tables or global deviation models. They cannot handle time-varying errors such as thermal deformation and mechanical wear, and are prone to ignoring long-distance cumulative errors. Therefore, the present invention uses visual servoing to measure the deviation between the actual position and the target position in real time, dynamically adjusts the control amount, and adopts segmented compensation to avoid global error transmission. It can effectively improve the control accuracy of the placement equipment movement and reduce the possibility of placement offset.
[0025] The secondary verification module is used to determine whether the placement device is at the target point C based on the second image information obtained by the vision module. If so, the process ends; if not, the position of the placement device is used as the calibration point A and returned to the vision measurement unit.
[0026] The above embodiments provide a detailed introduction to the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas. At the same time, for those skilled in the art, according to the ideas of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present invention.
Claims
1. A motion error compensation system based on dynamic segmented visual servoing, characterized in that: include: Driving module, fine-tuning compensation module and secondary calibration module; The driving module is used to control the placement equipment to move in a plane; The fine-tuning compensation module includes an initial control unit, a visual measurement unit and a compensation unit; The initial control unit is used to control the driving module according to the instruction to drive the placement device to move to the target point C, and mark the final stop position of the placement device as the calibration point A; the visual measurement unit is used to calculate the plane coordinates of the calibration point A based on the first image information obtained by the visual module The actual distance between the calibration point A and the target point C The compensation unit is used to calculate the actual distance The control drive module drives the placement equipment to move from the calibration point A to the target point C; The secondary verification module is used to determine whether the placement device is at the target point C based on the second image information obtained by the vision module. If so, the process ends; if not, the position of the placement device is used as the calibration point A and returned to the vision measurement unit.
2. The motion error compensation system based on dynamic segmented visual servoing according to claim 1, characterized in that: In the visual measurement unit, the following steps are specifically included: S11. Take the initial position of the placement equipment as the origin 0, and use the horizontal and vertical guide rails as the x-axis and y-axis to construct a plane coordinate system. Mark the plane coordinate of the target point C in the plane coordinate system. ; S12: Use a visual module to photograph the target point C and the calibration point A to obtain first image information; S13: Calculate the actual distance between the target point C and the calibration point A based on the first image information. .
3. The motion error compensation system based on dynamic segmented visual servoing according to claim 2, characterized in that: In step S13, the following steps are specifically included: S131, using the center point of the first image information as the origin 0, and constructing an image coordinate system with the horizontal and vertical axes of the first image information being u and v, respectively; S132: Extract the pixel coordinates of the correction point A in the image coordinate system. ; S133, calculate the lateral mechanical deviation compensation and longitudinal mechanical deviation compensation ; S134, according to the lateral mechanical deviation compensation and longitudinal mechanical deviation compensation The pixel coordinates of the correction point A Convert the plane coordinates of the correction point A to the plane coordinate system ; S135, according to the plane coordinates of calibration point A Calculate actual distance , and its calculation formula is: ， Where, Indicates the actual distance between calibration point A and target point C.
4. The motion error compensation system based on dynamic segmented visual servoing according to claim 3, characterized in that: In step S133, the following steps are specifically included: S1331, in the actual path of the placement device moving from origin 0 to calibration point A, the actual path is evenly divided into n first sub-paths, each of which has a length of ; S1332: Connect the origin 0 and the target point C in the plane coordinate system to generate an ideal path, and evenly divide the ideal path into n second sub-paths, each of which has a length of ; S1333. Extract the end point coordinates of each first subpath and the end point coordinates of the second subpath , and calculate the first deviation , and its calculation formula is: ， in, ， ， in, express function; represents the direction angle of the second subpath; ; S1334, according to the first deviation Calculate the lateral mechanical deviation compensation of the kth first subpath and longitudinal mechanical deviation compensation ; S1335: Repeat steps S1333-S1334 until the end point, and output the lateral mechanical deviation compensation amount. and longitudinal mechanical deviation compensation .
5. The motion error compensation system based on dynamic segmented visual servoing according to claim 4, characterized in that: In step S1334, the lateral mechanical deviation compensation amount and longitudinal mechanical deviation compensation The calculation formula is: ， Where, Represents the learning rate.
6. The motion error compensation system based on dynamic segmented visual servoing according to claim 3, characterized in that: In step S134, the plane coordinates of point A are corrected. The conversion formula is: ， Where, and Respectively represent the conversion coefficients of pixels on the u-axis and v-axis to physical coordinates; Indicates the origin coordinates of the image coordinate system.
7. The motion error compensation system based on dynamic segmented visual servoing according to claim 1, characterized in that: In the compensation unit, the following steps are specifically included: S21, according to the plane coordinates of calibration point A and the plane coordinates of the target point C Construct the target line segment AC and calculate its azimuth , and its calculation formula is: ， S22, the driving module controls the placement device to move along the target line segment AC, and the vision module acquires the second image information at a fixed frequency; S23, extract the current real-time position P of the placement device, and extract the plane coordinates of point P in the plane coordinate system ; S24, according to the azimuth Calculate the ideal plane coordinates of point P , and its calculation formula is: ， Where, Indicates the actual moving distance of the placement equipment; S25, according to the ideal plane coordinates Calculate the second deviation , and its calculation formula is: ， S26, according to the second deviation Calculate the superposition compensation amount ; S27, according to the superposition compensation amount Compensate for the motion of the drive module.
8. The motion error compensation system based on dynamic segmented visual servoing according to claim 7, characterized in that: In step S26, the compensation amount is added The calculation formula is: ， Where, 、 and Respectively represent PID parameters; in, ， ， ， Where, represents the critical oscillation period; Indicates the time required for the motor response to reach 63.2% of its steady-state value.