Chip mounter CA axis motion control method, chip mounter CA axis and Z axis coordinated motion control method

Abstract

The application relates to the technical field of motion control of a chip mounter, and discloses a CA shaft motion control method of a chip mounter and a CA shaft and Z shaft coordinated motion control method, which divides the complete rotation stroke of the CA shaft into a first section, a second section and a third section which are sequentially connected, and dynamically calculates a uniform speed section photographing speed vp according to the photographing group number of a flying camera. According to the scheme, the motion time is significantly reduced when the photographing group number is large, and the scheme is not inferior to the existing optimal scheme when the photographing group number is small, so that the CA shaft motion time under different photographing group numbers is effectively optimized.

Description

Technical Field

[0001] This application relates to the field of motion control technology for pick and place machines, and in particular to a motion control method for the CA axis of a pick and place machine and a coordinated motion control method for the CA axis and Z axis of a pick and place machine. Background Technology

[0002] After a pick-and-place machine picks up components, it typically needs to use a flying camera to photograph and identify the components on the nozzles to obtain their positional and angular deviations, guiding subsequent placement operations. In a flying imaging scheme using an area scan camera, the CA axis drives a reflector to rotate via a cam structure, enabling the area scan camera to capture images of the components on each nozzle from a specific angle. Due to the transmission characteristics of the cam structure, the CA axis must continue to rotate 360 ​​degrees after each imaging action to return the reflector to its original position before the next action can begin; furthermore, due to the limitation of the cam's constant-speed position, the imaging action can only be performed within a specific angular range.

[0003] To address the aforementioned structural constraints, there are typically two approaches to the CA-axis's photographing motion. In the first approach, the CA-axis moves from the origin to the photographing position and then remains stationary until the flight camera completes all group photographs. Only then does it continue moving to 360 degrees. In this approach, both phases of motion can be executed at maximum speed and acceleration. However, due to the inclusion of two complete acceleration and deceleration processes, the combined acceleration and deceleration times of the two phases result in a longer total motion time when the number of photographing groups is small. In the second approach, the CA-axis moves directly from the origin to 360 degrees and then moves at a constant speed through a designated photographing angle range. Within this constant-speed phase, it completes group photographs by the flight camera before continuing to 360 degrees. In this approach, the speed during the constant-speed phase must be determined based on the number of photographing groups: the more photographing groups, the longer the required constant-speed phase, forcing a reduction in speed and significantly increasing the overall motion time of the CA-axis. Both approaches have limitations and cannot simultaneously maintain a low motion time for different numbers of photographing groups.

[0004] Furthermore, in the placement process of a pick-and-place machine, the CA axis's photo-taking action, the Z axis's pick-up and return action, and the placement descent action are usually executed sequentially. The Z axis must wait for the CA axis to complete a 360-degree rotation before it can start subsequent actions. The individual action time of the CA axis directly occupies the entire machine's placement cycle time, causing significant waiting pauses in the Z, R, X, and Y axes, resulting in lag in the entire placement process and significantly restricting placement efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide a motion control method for the CA axis of a pick-and-place machine, a coordinated motion control method for the CA and Z axes of a pick-and-place machine, and a control system for improving the motion efficiency of the CA axis of a pick-and-place machine, so as to solve the following technical problems existing in the prior art: (1) In the existing chip mounter, the CA axis driven by the cam structure must rotate 360 ​​degrees to return the reflector to the origin after the flying camera takes a picture. Moreover, the picture taking action can only be performed within the fixed angle range corresponding to the constant speed segment of the cam. Both existing motion schemes have obvious limitations: the first scheme contains two complete acceleration and deceleration processes, and the total motion time is too long when the number of picture groups is small; in the second scheme, the speed in the constant speed segment must decrease as the number of picture groups increases, which leads to a significant increase in the motion time of the CA axis when the number of picture groups is large. Neither scheme can maintain a low motion time at the same time under different number of picture groups. (2) In the existing placement process of the pick-and-place machine, the CA axis photo-taking action and the Z axis pick-and-place return action and placement descent action are executed in sequence. There is a lack of effective utilization of the overlapping range of CA axis and Z axis actions. The CA axis action time alone directly occupies the whole machine placement cycle time, resulting in obvious waiting pauses on the Z axis, R axis, X axis and Y axis. The whole machine placement process is stuck, and the placement efficiency is significantly restricted.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: The first aspect of this invention provides a motion control method for the CA axis of a chip mounter. The CA axis is driven by a cam structure. Each photo-taking action requires completing a full rotational stroke to return the reflector to its origin position. The photo-taking angle range is located within the constant-speed rotation range of the cam. The complete rotational stroke of the CA axis is divided into a first segment, a second segment, and a third segment connected sequentially. The constant-speed photo-taking speed vp is dynamically calculated based on the number of photo-taking groups by the flying camera. The first segment is the motion segment of the CA axis from its origin position to the starting angle of the photo-taking, which is planned using a smooth speed curve with an initial velocity of 0 and a final velocity of vp, and moves according to the maximum speed and maximum acceleration of the CA axis. The second segment is the motion segment of the CA axis from the starting angle of the photo-taking to the ending angle of the photo-taking, which performs constant-speed motion at vp, and completes the group photo-taking of all groups of flying cameras during this constant-speed motion. The third segment is the motion segment of the CA axis from the ending angle of the photo-taking to the end of the complete rotational stroke, which is planned using a smooth speed curve with an initial velocity of vp and a final velocity of 0, and moves according to the maximum speed and maximum acceleration of the CA axis.

[0007] A second aspect of the present invention provides a method for coordinated motion control of the CA axis and Z axis of a pick-and-place machine, the pick-and-place machine including a CA axis driven by a cam structure and a lifting Z axis; Safety thresholds for the pick-up stage and the placement stage are obtained in advance through calibration. The safety thresholds for the pick-up stage include the CA axis angle threshold and the Z axis height threshold for the pick-up stage. The safety thresholds for the placement stage include the CA axis angle threshold and the Z axis height threshold for the placement stage. The Z axis height threshold for the placement stage is equal to the calibrated Z axis height minus the deceleration stop travel margin of the Z axis at maximum speed. During the absorption phase, based on the time required for the CA axis to move from the origin to the starting angle of the image capture, the first Z-axis position corresponding to the same time the Z-axis moves backward along the motion curve from the recognition height is calculated. Simultaneously, based on the time required for the CA axis to move from the origin to the CA axis angle threshold of the absorption phase, the second Z-axis position corresponding to the same time the Z-axis moves backward along the motion curve from the Z-axis height threshold of the absorption phase is calculated. Comparing the first Z-axis position and the second Z-axis position, the position closer to the Z-axis height threshold of the absorption phase is taken as the Z-axis trigger position for the absorption phase. When the Z-axis is detected to move to the Z-axis trigger position of the absorption phase in real time, the CA axis is triggered to start moving, so that when the Z-axis reaches the recognition height and stops, the CA axis reaches the starting angle of the image capture, thus achieving time overlap of the two axes' movements during the absorption phase. During the mounting stage, the sum of the time required for the Z-axis to move from the identification height to the mounting stage Z-axis height threshold and the time required for the CA-axis to move from the mounting stage CA-axis angle threshold to the end of the complete rotation stroke is used to calculate the CA-axis angle corresponding to when the CA-axis triggers the Z-axis to start moving downwards. This angle is then used as the CA-axis trigger angle for the mounting stage. When the CA-axis is detected to have moved to the CA-axis trigger angle for the mounting stage, the Z-axis is triggered to move downwards from the identification height. This ensures that when the CA-axis moves to the CA-axis angle threshold for the mounting stage, the lowest point of the Z-axis is above the mounting stage Z-axis height threshold, thus achieving time overlap of the two axes' movements during the mounting stage.

[0008] A third aspect of the present invention provides a control system for improving the motion efficiency of the CA axis of a pick-and-place machine, comprising a controller, a CA axis drive mechanism driven by a cam structure, a lifting axis drive mechanism, and a position detection unit; it also includes a motion curve planning module and an inter-axis coordination triggering module, wherein the motion curve planning module and the inter-axis coordination triggering module are integrated within the controller; the motion curve planning module is configured to dynamically calculate the image capture speed vp based on the number of images captured by the flying camera, and divide the complete rotational stroke of the CA axis into three segments for smooth speed curve planning, with the image capture speed vp serving as the connecting speed between the three segments, and outputting a three-segment motion command to the CA axis drive mechanism; the inter-axis coordination triggering module is connected to the position detection unit, configured to store safety thresholds for the pick-up stage and the placement stage, and to reverse-calculate the Z-axis trigger position for the pick-up stage and the CA axis trigger angle for the placement stage based on the motion parameters of the CA axis and the Z-axis, respectively, and output a start signal to the CA axis drive mechanism or the lifting axis drive mechanism when the position detection unit detects the corresponding trigger condition.

[0009] Compared with the prior art, the present invention has the following beneficial effects: The CA-axis three-segment dynamic motion curve planning scheme divides the complete rotational stroke of the CA-axis into three segments and uses the shooting speed vp as the connecting speed. It can maintain a low motion time under different shooting groups. Compared with the existing scheme that only contains a single uniform speed segment, the motion time is significantly reduced when the number of shooting groups is large, and it is not inferior to the existing best scheme when the number of shooting groups is small. It achieves effective optimization of the CA-axis motion time under different shooting groups.

[0010] By using the overlapping action mechanism of the absorption phase, the CA axis is triggered when the Z-axis moves to the Z-axis trigger position obtained by reverse calculation. This allows the CA axis and Z-axis absorption and return actions to be performed in parallel, effectively compressing the separate waiting time of the CA axis in the absorption phase and eliminating the pause of the Z-axis waiting for the CA axis to start.

[0011] By employing an overlapping mechanism in the placement stage, the Z-axis is triggered to begin moving downwards when the CA axis moves to the CA axis trigger angle obtained from the reverse push. This allows the CA axis rotation and the Z-axis placement descent to occur in parallel, further reducing the individual action time of the CA axis in the placement stage. Combined with the overlapping of the pick-up stage, the individual action time of the CA axis in the entire placement process is significantly reduced, resulting in a significant improvement in the overall placement smoothness and effectively eliminating the placement lag caused by the CA axis waiting.

[0012] The safety threshold is obtained through calibration. During the placement stage, the safety threshold is calculated by subtracting the deceleration stop margin of the Z-axis at maximum speed from the calibrated Z-axis height. Even if an anomaly occurs during movement causing the motor to decelerate and stop, it ensures that no collision occurs between the CA and Z axes, resulting in high safety and reliability. The multi-Z-axis coordinated triggering strategy uses the Z-axis with the longest pick-up time and the Z-axis with the shortest placement time as benchmarks to ensure that all Z-axis meet safety constraints under any operating condition. Attached Figure Description

[0013] Figure 1 Velocity and position curves for a three-segment curve planning of the CA axis; Figure 2 A schematic diagram illustrating the positional relationship between the Z-axis and CA-axis during the absorption phase; Figure 3 A flowchart illustrating the method for coordinated motion control of the CA and Z axes during the absorption phase; Figure 4 This is a schematic diagram showing the positional relationship between the Z-axis and CA-axis during the mounting stage. Figure 5 This is a flowchart illustrating the method for coordinated motion control of the CA and Z axes during the mounting stage. Reference numerals: 1. CA axis motor; 2. Reflector; 3. Cam. Detailed Implementation

[0014] The present application will now be described in further detail with reference to the accompanying drawings and embodiments.

[0015] This application provides a motion control method for the CA axis of a pick-and-place machine, a coordinated motion control method for the CA and Z axes of a pick-and-place machine, and a control system for improving the motion efficiency of the CA axis of a pick-and-place machine. Addressing the structural constraints of the cam-driven CA axis requiring a complete 360-degree rotation for each image capture, with the image capture range fixed within the corresponding angle range of the cam's constant speed segment, this application utilizes a three-segment dynamic motion curve planning and a bidirectional motion overlap mechanism between the CA and Z axes. This effectively optimizes the CA axis motion time under different image capture groups and significantly reduces the individual motion time of the CA axis throughout the entire placement process, effectively eliminating placement jams and significantly improving placement efficiency.

[0016] Example 1

[0017] This embodiment provides a motion control method for the CA axis of a pick-and-place machine, applied to a CA axis driven by a cam structure in the pick-and-place machine. The pick-and-place head includes a cam structure CA axis drive mechanism, a plane array flying camera, and a reflector mounted on the CA axis. Each time the CA axis takes a picture, it must complete a full rotation stroke (360 degrees) to return the reflector to its original position. The picture angle range is fixed within the constant speed rotation range of the cam.

[0018] In this embodiment, the starting angle for taking the picture is 120 degrees, and the ending angle is 150 degrees, for a total of 30 degrees of constant-speed motion. This embodiment divides the complete rotational stroke of the CA axis into three sequentially connected segments, such as... Figure 1 As shown: The first segment is the movement of the CA axis from the origin (0 degrees) to the starting angle of the photograph (120 degrees), with a distance of 120 degrees. This segment uses a smooth velocity curve with an initial velocity of 0 and a final velocity equal to the dynamic photographing speed vp. The movement follows the maximum velocity and maximum acceleration of the CA axis, ensuring that the velocity of the CA axis is exactly equal to vp when it reaches 120 degrees. Specifically, the smooth velocity curve is designed using a seven-segment S-curve with initial and final velocities, as described in invention patents CN114740806A or CN114879609A.

[0019] The second segment involves the CA axis moving from the initial shooting angle (120 degrees) to the final shooting angle (150 degrees), with a travel distance of 30 degrees. This segment executes a constant speed motion (vp), completing all group shots of the flying camera during this constant speed motion. The shooting speed vp = shooting angle range travel distance ÷ (single shooting time of the flying camera × number of shooting groups). The more shooting groups, the lower the vp. Before each placement cycle, the controller reads the current number of shooting groups and dynamically calculates vp, enabling the CA axis motion parameters to adaptively adjust according to shooting requirements.

[0020] The third segment is the motion of the CA axis from the end angle of the photograph (150 degrees) to the end of the complete rotational stroke (360 degrees), with a stroke of 210 degrees. This segment uses a smooth velocity curve with an initial velocity of vp and a final velocity of 0, moving according to the maximum velocity and maximum acceleration of the CA axis. It is also implemented using a seven-segment S-curve planning scheme with initial and final velocities. The three segments are smoothly connected with vp as the connecting velocity, eliminating the time loss of two complete acceleration and deceleration processes in the existing scheme one.

[0021] The workflow of the CA axis three-segment dynamic motion curve planning scheme in this embodiment is as follows: The controller reads the current number of cyclic photo groups and calculates vp; the CA axis starts to execute the first segment of acceleration motion, and when it reaches 120 degrees, the speed is exactly equal to vp; it switches to the second segment of uniform motion and triggers the flight camera to take photos in groups; after reaching 150 degrees, it switches to the third segment of deceleration motion until it completes a 360-degree rotation and returns to the original position.

[0022] Thanks to the adoption of a three-segment motion curve planning with vp as the transition speed, the CA axis maintains a low motion time regardless of the number of photo frames. The three-segment motion curve planning scheme eliminates the time loss of two complete acceleration and deceleration processes. When the number of photo frames is large, the motion time is significantly lower than the traditional constant speed scheme, and when the number of photo frames is small, it is not inferior to the traditional scheme, thus achieving effective optimization of the CA axis motion time under different numbers of photo frames.

[0023] Example 2

[0024] Based on Example 1, this embodiment further provides a method for coordinated motion control of the CA and Z axes of a pick-and-place machine, focusing on describing the coordinated triggering mechanism for the overlapping of CA and Z axis movements during the pick-up phase.

[0025] The placement head of a pick-and-place machine includes a CA axis drive mechanism, multiple lifting axes (Z axes), and a position detection unit. The CA axis drives the reflector to rotate, while the Z axis is responsible for the lifting and lowering of the nozzle. There is a risk of motion interference between the two axes.

[0026] This embodiment first obtains the safety threshold for the absorption phase through calibration. The calibration method is as follows: a jig of the maximum size that the flight camera is allowed to recognize is placed on the Z-axis. In this embodiment, a cylindrical jig with a diameter of 17 mm and a thickness of 6.5 mm is used.

[0027] like Figure 2As shown, after locking the Z-axis to its lowest position, manually rotate the CA-axis until the reflector 2 contacts the Z-axis moving cylindrical surface. The CA-axis mainly includes the reflector 2, cam 3, belt, and CA-axis motor 1. After locking the CA-axis motor, unlock the Z-axis and manually adjust the Z-axis height until the lowest point of the Z-axis is exactly above the CA-axis reflector 2. Record the corresponding CA-axis angle and Z-axis height data. In this embodiment, when the CA-axis reflector 2 contacts the Z-axis moving cylindrical surface, the CA-axis angle is between 55 and 60 degrees, and the Z-axis height is approximately 30 mm to 35 mm. After taking a safety margin, determine the CA-axis angle threshold for the suction stage to be 50 degrees and the Z-axis height threshold for the suction stage to be 25 mm. When the CA-axis is at the 50-degree position, the lowest point of the Z-axis must be above 25 mm to ensure that no collision occurs.

[0028] Based on the aforementioned safety threshold, this embodiment determines the Z-axis trigger position of the absorption stage through reverse calculation.

[0029] The specific method is as follows: Based on the time required for the CA axis to move from the origin position (0 degrees) to the starting angle for taking the picture (120 degrees), the first Z-axis position corresponding to the same time the Z-axis moves backward along the motion curve from the recognition height is calculated. Simultaneously, based on the time required for the CA axis to move from the origin position to the CA axis angle threshold of the absorption stage, the second Z-axis position corresponding to the same time the Z-axis moves backward along the motion curve from the Z-axis height threshold of the absorption stage is calculated. The first Z-axis position and the second Z-axis position are compared, and the position closer to the Z-axis height threshold of the absorption stage is taken as the Z-axis trigger position for the absorption stage. When the position detection unit detects in real time that the Z-axis has moved to the Z-axis trigger position for the absorption stage, the CA axis is triggered to start moving, so that when the Z-axis reaches the recognition height and comes to rest, the CA axis exactly reaches the starting angle for taking the picture (120 degrees).

[0030] like Figure 3 As shown, the time T1 for the CA axis to move to the safety threshold (50 degrees) is calculated based on the CA axis's imaging speed, and the time T2 for the CA axis to move from 50 degrees to 120 degrees is also calculated. Simultaneously, the time for each z-axis to reach the safety threshold (25mm) position is calculated, and the longest-lasting z-axis is identified. The CA axis as a whole includes the reflector 2, cam 3, belt, and CA axis motor 1. The position X of the z-axis is calculated by reversing the movement time T1+T2 from the recognition position (5mm), and the position Y of the z-axis is calculated by reversing the movement time T1 from the safety threshold (25mm). Positions X and Y are compared, and the higher position Z is selected. It is determined whether the acquisition position is higher than Z. If so, the CA axis starts moving when the z-axis reaches position Z; otherwise, the CA axis starts moving directly. Finally, the z-axis reaches the recognition position and comes to a stop, while the CA axis reaches the imaging start position.

[0031] In summary, the coordinated control process during the absorption phase is as follows: After the Z-axis completes the absorption action, it returns upward from the absorption position, and the controller monitors the Z-axis position in real time. When the Z-axis reaches the Z-axis trigger position of the absorption phase, it triggers the CA axis to start moving; thereafter, the Z-axis continues to rise until it stops at the recognition height, and the CA axis just reaches the starting angle for taking pictures, and the grouping of pictures by the flying camera begins.

[0032] The pick-and-place machine contains multiple Z-axis, each with different speed conditions. Using the Z-axis that takes the longest time to reach the pick-up stage height threshold (25mm) as a benchmark, the corresponding CA axis trigger time is calculated. When the Z-axis with the longest time reaches the corresponding pick-up stage trigger position, the CA axis is triggered to start moving. The CA axis can only start after all Z-axis meet the safety conditions.

[0033] For example, taking a typical working condition (Z-axis pick-up position 60mm, recognition height 5mm, one set of photos, maximum speed of multiple Z-axis) as an example for effect analysis: Without motion overlap, the Z-axis pick-up return, CA-axis movement, and Z-axis pre-descent are executed sequentially, with a total motion time of 305ms. After introducing motion overlap during the pick-up phase, the overlap time between the two axes is 58ms, and the total motion time is reduced to 247ms, effectively eliminating the pause time of the Z-axis waiting for the CA-axis to start.

[0034] Thanks to the adoption of a coordinated triggering mechanism for the absorption phase based on safety threshold calibration and motion parameter back-calculation, the CA axis and Z axis movements overlap during the absorption phase, saving 58ms and reducing the total motion time from 305ms to 247ms, effectively eliminating the pause when the Z axis waits for the CA axis to start.

[0035] Example 3

[0036] Based on Example 2, this embodiment further provides a coordinated control mechanism for the overlapping of CA and Z axis movements during the mounting stage, and considers the safety margin for Z axis deceleration and stopping.

[0037] This embodiment first obtains the safety threshold for the mounting stage through calibration. The calibration method is as follows: Place the largest size fixture (17mm in diameter, 6.5mm in thickness) that the flight camera can recognize on the Z-axis. After rotating the CA axis to the end position of the full rotation stroke (360 degrees), lock the Z-axis in the lowest position, and manually rotate the CA axis in the opposite direction until the CA axis contacts the moving cylindrical surface of the Z-axis. After locking the CA axis, unlock the Z-axis, and manually adjust the height of the Z-axis until the lowest point of the Z-axis is exactly above the CA axis reflector 2, and record the corresponding CA axis angle and Z-axis height data.

[0038] In this embodiment, when the CA axis leaves the Z-axis moving cylindrical surface during the placement stage, the CA axis angle is between 260 and 265 degrees, and the Z-axis height is approximately 30 mm to 35 mm. Considering that abnormal errors may occur in actual production, causing the motor to decelerate and stop, the safety threshold during the placement stage must be calculated by subtracting the deceleration stop travel margin of the Z-axis at its maximum speed from the calibrated Z-axis height. The deceleration stop travel is calculated and determined based on the maximum speed of the Z-axis and the deceleration stop speed.

[0039] After determining the safety margin, the CA axis angle threshold for the placement stage is set at 270 degrees, and the Z axis height threshold for the placement stage is set at 15mm (including deceleration and stop travel margin). For example... Figure 4 As shown, when the CA axis moves to 270 degrees, the lowest point of the Z axis must be at least 15mm to ensure that there is no collision even if deceleration and stopping occur. Based on the above safety threshold, this embodiment determines the CA axis trigger angle during the placement stage through reverse calculation.

[0040] The specific method is as follows: Based on the motion curves of the Z-axis and CA-axis, calculate the sum of the time required for the Z-axis to move from the recognition height to the Z-axis height threshold (15mm) in the placement stage and the time required for the CA-axis to move from the CA-axis angle threshold (270 degrees) in the placement stage to the end of the complete rotation stroke (360 degrees), and obtain the total overlap time. Then, calculate the CA-axis angle corresponding to when the CA-axis triggers the Z-axis to begin its downward movement; this is the CA-axis trigger angle in the placement stage.

[0041] like Figure 5 As shown, the time T3 for the CA axis to move from 270 degrees to 360 degrees is calculated based on the CA axis's imaging speed. Simultaneously, the time T4 for each z-axis to reach the safety threshold position of 15 mm from a recognition height of 5 mm is calculated to determine the shortest Z-axis time. The position X when the CA axis moves backward from 360 degrees (T3 + T4 time) is calculated. The Z-axis begins to move when the CA axis reaches position X, and reaches the 15 mm position when the CA axis reaches 270 degrees.

[0042] In summary, the coordinated control process during the placement stage is as follows: After the CA axis completes its image capture, it continues to rotate, and the controller monitors the CA axis angle in real time. When the CA axis reaches the placement stage's trigger angle, it triggers the Z axis to move downwards from the recognition height (5mm). When the CA axis reaches 270 degrees, the lowest point of the Z axis is above 15mm, meeting the safety constraints; subsequently, the Z axis continues to descend to the placement position, and the CA axis completes a 360-degree rotation. When the pick-and-place machine contains multiple Z axes, the Z axis with the shortest time to reach the placement stage Z axis height threshold (15mm) is used as the benchmark to calculate the angle at which the CA axis triggers the Z axis to descend. When the CA axis reaches the placement stage's trigger angle, it triggers all Z axes to move downwards from the recognition height, ensuring that even the fastest Z axis meets the safety conditions, maximizing the overlap time of actions while ensuring safety.

[0043] The effect is analyzed using a typical working condition (Z-axis pick-up position 60mm, recognition height 5mm, mounting height 55mm, one set of photos, maximum speed of multiple Z-axis axes) as an example. Based on the introduction of overlap in the pick-up stage (saving 58ms), the overlap of the mounting stage is further introduced, and the overlap time of the two-axis actions in the mounting stage is 67ms, further reducing the total motion time from 247ms to 180ms.

[0044] After the pick-up action overlaps, the CA axis begins to move at 50mm along the Z-axis. From the time the CA axis reaches 360 degrees, the overlap saves 58ms. After the placement action overlaps, the CA axis begins to move at 205 degrees. From the time the CA axis reaches 360 degrees and the Z-axis reaches the placement position, the overlap saves 67ms. Therefore, the individual movement time of the CA axis in the entire placement process is only 25ms, saving a total of 125ms. This significantly improves the smoothness of the entire placement process and effectively eliminates placement stuttering caused by CA axis waiting.

[0045] Example 4

[0046] This embodiment provides a control system for improving the motion efficiency of the CA axis of a chip mounter, used to implement the control methods described in Embodiments 1 to 3 above.

[0047] The control system includes a controller, a CA-axis drive mechanism driven by a cam structure, a lifting axis drive mechanism, a position detection unit, a motion curve planning module, and an inter-axis coordination triggering module. The motion curve planning module and the inter-axis coordination triggering module are integrated within the controller. The CA-axis drive mechanism, driven by a cam structure, rotates the reflector 2 around the CA axis, returning it to its original position after each 360-degree rotation. The lifting axis drive mechanism drives multiple Z-axises to move vertically up and down.

[0048] The position detection unit includes encoders installed on the CA axis and each Z axis respectively, which collect the angle of the CA axis and the height position information of each Z axis in real time and feed them back to the controller.

[0049] The motion curve planning module is configured to dynamically calculate the shooting speed vp based on the number of shooting groups of the flight camera, divide the complete rotation stroke of the CA axis into three segments for motion curve planning, and output three-segment motion commands to the CA axis drive mechanism.

[0050] The motion curve planning module has a built-in seven-segment S-curve planning algorithm with initial and final velocities. The three-segment motion command includes: the first segment is a motion command with an initial velocity of 0 and a final velocity of vp from the origin position to the starting angle of the photo capture; the second segment is a photo capture trigger command with a constant velocity of vp from the starting angle of the photo capture to the ending angle of the photo capture; and the third segment is a motion command with an initial velocity of vp and a final velocity of 0 from the ending angle of the photo capture to the end point of the complete rotation journey.

[0051] The inter-axis coordination triggering module is connected to the position detection unit and is configured to store the calibrated safety thresholds for the pick-up stage and the placement stage. The inter-axis coordination triggering module is also configured to reverse-calculate the Z-axis trigger position for the pick-up stage and the CA-axis trigger angle for the placement stage based on the motion parameters of the CA-axis and each Z-axis, and to output a start signal to the CA-axis drive mechanism or the lifting axis drive mechanism when the position detection unit detects the corresponding trigger condition.

[0052] The inter-axis coordination triggering module supports calculating the trigger position for multiple Z-axis separately, and outputs coordinated triggering signals for CA axis and Z axis respectively based on the Z axis with the longest time in the absorbing stage and the Z axis with the shortest time in the mounting stage, ensuring that all Z axes meet the safety constraints under any working condition.

[0053] The workflow of the control system in this embodiment is as follows: At the beginning of each placement cycle, the controller reads the current number of photo groups by the motion curve planning module, dynamically calculates VP, and plans a three-segment motion curve.

[0054] During the absorption phase, the inter-axis coordination triggering module monitors the position of each Z-axis in real time. When the Z-axis with the longest absorption time reaches the Z-axis triggering position of the absorption phase, it outputs a start signal to the CA axis drive mechanism.

[0055] During the placement stage, the inter-axis coordination trigger module monitors the CA axis angle in real time. When the CA axis reaches the CA axis trigger angle for the placement stage, it outputs a start signal to the lifting axis drive mechanism, triggering all Z axes to start moving downward synchronously.

[0056] Thanks to the system architecture that integrates motion curve planning module and inter-axis coordination triggering module, three-segment curve planning and bidirectional inter-axis overlap control are systematically integrated and realized, supporting coordinated triggering of multiple Z axes. This makes it suitable for industrial high-speed placement machine scenarios and significantly improves the overall placement efficiency.

[0057] It is understood that the shooting angle range is not limited to 120 degrees to 150 degrees, and can also be adjusted to other constant speed ranges according to different cam structure designs. The three-segment planning method is also applicable.

[0058] It is understood that the safety threshold is not limited to being obtained through manual calibration, but can also be obtained through simulation calculation or theoretical derivation, and the safety margin is used to back-calculate the trigger position.

[0059] It is understood that the number of Z-axis can be determined according to the actual pick-and-place machine configuration, and the multi-Z-axis coordinated triggering strategy is also applicable to different numbers of multi-Z-axis configurations.

[0060] Obviously, the seven-segment S-curve planning with initial and final velocities is not limited to the specific implementation given in this application. Other smooth velocity planning methods that satisfy initial and final velocity constraints can be substituted, as long as they can achieve a smooth connection of three segments with vp as the connecting velocity.

[0061] In summary, the present invention has the following beneficial effects: The CA-axis three-segment dynamic motion curve planning scheme divides the complete rotational stroke of the CA-axis into three segments and uses the shooting speed vp as the connecting speed. It can maintain a low motion time under different shooting groups. Compared with the existing scheme that only contains a single uniform speed segment, the motion time is significantly reduced when the number of shooting groups is large, and it is not inferior to the existing best scheme when the number of shooting groups is small. It achieves effective optimization of the CA-axis motion time under different shooting groups.

[0062] By using the overlapping action mechanism of the absorption phase, the CA axis is triggered when the Z-axis moves to the Z-axis trigger position obtained by reverse calculation. This allows the CA axis and Z-axis absorption and return actions to be performed in parallel, effectively compressing the separate waiting time of the CA axis in the absorption phase and eliminating the pause of the Z-axis waiting for the CA axis to start.

[0063] By employing an overlapping mechanism in the placement stage, the Z-axis is triggered to begin moving downwards when the CA axis moves to the CA axis trigger angle obtained from the reverse push. This allows the CA axis rotation and the Z-axis placement descent to occur in parallel, further reducing the individual action time of the CA axis in the placement stage. Combined with the overlapping of the pick-up stage, the individual action time of the CA axis in the entire placement process is significantly reduced, resulting in a significant improvement in the overall placement smoothness and effectively eliminating the placement lag caused by the CA axis waiting.

[0064] The safety threshold is obtained through calibration. During the placement stage, the safety threshold is calculated by subtracting the deceleration stop margin of the Z-axis at maximum speed from the calibrated Z-axis height. Even if an anomaly occurs during movement causing the motor to decelerate and stop, it ensures that no collision occurs between the CA and Z axes, resulting in high safety and reliability. The multi-Z-axis coordinated triggering strategy uses the Z-axis with the longest pick-up time and the Z-axis with the shortest placement time as benchmarks to ensure that all Z-axis meet safety constraints under any operating condition.

[0065] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the inventive concept of this application, and these all fall within the protection scope of this application.

Claims

1. A motion control method for the CA axis of a pick-and-place machine, wherein the CA axis is driven by a cam structure, and each image capture action requires completing a full rotation stroke to return the reflector to its origin position, with the image capture angle range located within the constant-speed rotation range of the cam; characterized in that, The complete rotational stroke of the CA axis is divided into three sequentially connected segments: the first segment, the second segment, and the third segment. The constant-speed shooting speed vp is dynamically calculated based on the number of camera groups. The first segment is the movement of the CA axis from the origin to the starting angle of the shooting, using a smooth speed curve with an initial velocity of 0 and a final velocity of vp, moving at the maximum speed and maximum acceleration of the CA axis. The second segment is the movement of the CA axis from the starting angle of the shooting to the ending angle of the shooting, performing constant-speed movement at vp, during which all groups of camera groups are photographed. The third segment is the movement of the CA axis from the ending angle of the shooting to the end of the complete rotational stroke, using a smooth speed curve with an initial velocity of vp and a final velocity of 0, moving at the maximum speed and maximum acceleration of the CA axis.

2. The pick-and-place machine CA axis motion control method according to claim 1, characterized in that, The shooting speed vp = shooting angle range travel ÷ (single shooting time of the flight camera × number of shooting groups); the constant speed motion range between the shooting start angle and the shooting end angle is determined by the constant speed segment design of the cam structure.

3. A method for coordinated motion control of the CA and Z axes of a pick-and-place machine, the pick-and-place machine comprising a CA axis driven by a cam structure and a lifting Z axis; characterized in that, Safety thresholds for the pick-up stage and the placement stage are obtained in advance through calibration. The safety thresholds for the pick-up stage include the CA axis angle threshold and the Z axis height threshold for the pick-up stage. The safety thresholds for the placement stage include the CA axis angle threshold and the Z axis height threshold for the placement stage. The Z axis height threshold for the placement stage is equal to the calibrated Z axis height minus the deceleration stop travel margin of the Z axis at maximum speed. During the absorption phase, based on the time required for the CA axis to move from the origin to the starting angle of the image capture, the first Z-axis position corresponding to the same time the Z-axis moves backward along the motion curve from the recognition height is calculated. Simultaneously, based on the time required for the CA axis to move from the origin to the CA axis angle threshold of the absorption phase, the second Z-axis position corresponding to the same time the Z-axis moves backward along the motion curve from the Z-axis height threshold of the absorption phase is calculated. Comparing the first Z-axis position and the second Z-axis position, the position closer to the Z-axis height threshold of the absorption phase is taken as the Z-axis trigger position for the absorption phase. When the Z-axis is detected to move to the Z-axis trigger position of the absorption phase in real time, the CA axis is triggered to start moving, so that when the Z-axis reaches the recognition height and stops, the CA axis reaches the starting angle of the image capture, thus achieving time overlap of the two axes' movements during the absorption phase. During the mounting stage, the sum of the time required for the Z-axis to move from the identification height to the mounting stage Z-axis height threshold and the time required for the CA-axis to move from the mounting stage CA-axis angle threshold to the end of the complete rotation stroke is used to calculate the CA-axis angle corresponding to when the CA-axis triggers the Z-axis to start moving downwards. This angle is then used as the CA-axis trigger angle for the mounting stage. When the CA-axis is detected to have moved to the CA-axis trigger angle for the mounting stage, the Z-axis is triggered to move downwards from the identification height. This ensures that when the CA-axis moves to the CA-axis angle threshold for the mounting stage, the lowest point of the Z-axis is above the mounting stage Z-axis height threshold, thus achieving time overlap of the two axes' movements during the mounting stage.

4. The method for coordinated motion control of the CA and Z axes of a pick-and-place machine according to claim 3, characterized in that, The calibration method for the safety threshold of the absorption phase is as follows: Place the largest size fixture that the flight camera can recognize on the Z-axis, lock the Z-axis at the lowest position, manually rotate the CA-axis to the contact position between the CA-axis and the Z-axis moving cylindrical surface, lock the CA-axis, unlock the Z-axis and manually adjust the height of the Z-axis until the lowest point of the Z-axis is exactly above the CA-axis reflector, record the corresponding CA-axis angle and Z-axis height, and take the safety margin to determine the CA-axis angle threshold and the Z-axis height threshold of the absorption phase. The Z-axis moving cylindrical surface is obtained based on the size of the maximum adsorption element.

5. The method for coordinated motion control of the CA and Z axes of a pick-and-place machine according to claim 3, characterized in that, The pick-and-place machine includes multiple Z-axis; during the pick-and-place phase, the Z-axis that takes the longest time to reach the Z-axis height threshold of the pick-and-place phase is used as a reference, and the corresponding CA axis trigger time is calculated in reverse. When the Z-axis that takes the longest time moves to the corresponding Z-axis trigger position of the pick-and-place phase, the CA axis is triggered to start moving.

6. The method for coordinated motion control of the CA and Z axes of a pick-and-place machine according to claim 3, characterized in that, The calibration method for the safety threshold of the mounting stage is as follows: Place the largest size fixture that the flight camera can recognize on the Z-axis, rotate the CA-axis to the end position of the full rotation stroke, lock the Z-axis at the lowest position, manually rotate the CA-axis in the opposite direction until the CA-axis and the Z-axis moving cylindrical surface are in contact, lock the CA-axis, unlock the Z-axis and manually adjust the Z-axis height until the lowest point of the Z-axis is exactly above the CA-axis reflector, record the corresponding CA-axis angle and Z-axis height, and subtract the stroke margin required for the Z-axis to come to a complete stop at the maximum speed by deceleration, and then determine the CA-axis angle threshold and the Z-axis height threshold of the mounting stage.

7. The method for coordinated motion control of the CA and Z axes of a pick-and-place machine according to any one of claims 3-6, characterized in that, The pick-and-place machine includes multiple Z-axis; during the placement stage, the Z-axis that takes the shortest time to reach the Z-axis height threshold of the placement stage is used as a reference, and the angle at which the CA axis triggers the Z-axis to descend is calculated. When the CA axis moves to the CA axis trigger angle of the placement stage, all Z-axis are triggered to move downward from the identification height.

8. The method for coordinated motion control of the CA and Z axes of a pick-and-place machine according to claim 7, characterized in that, The method for calculating the CA axis trigger angle in the mounting stage is as follows: add the time required for the Z axis to move from the identification height to the Z axis height threshold in the mounting stage to the time required for the CA axis to move from the CA axis angle threshold in the mounting stage to the end of the complete rotation stroke to obtain the total overlap time; based on the motion curve of the CA axis, calculate the angle position of the CA axis when it reaches the end of the complete rotation stroke after completing the total overlap time, which is the CA axis trigger angle in the mounting stage.

9. A control system for improving the efficiency of the CA axis movement in a pick-and-place machine, comprising a controller, a CA axis drive mechanism driven by a cam structure, a lifting axis drive mechanism, and a position detection unit; characterized in that, It also includes a motion curve planning module and an inter-axis coordination triggering module, which are integrated into the controller. The motion curve planning module is configured to dynamically calculate the shooting speed vp based on the number of shooting groups of the flight camera, and divide the complete rotation stroke of the CA axis into three segments for smooth speed curve planning. The three segments are connected by the shooting speed vp, and the three-segment motion commands are output to the CA axis drive mechanism. The inter-axis coordination triggering module is connected to the position detection unit and is configured to store the safety threshold of the pick-up stage and the safety threshold of the mounting stage. It reverse-calculates the Z-axis trigger position of the pick-up stage and the CA-axis trigger angle of the mounting stage based on the motion parameters of the CA axis and Z axis, and outputs a start signal to the CA axis drive mechanism or the lifting axis drive mechanism when the position detection unit detects the corresponding trigger condition.

10. The pick-and-place machine CA axis motion efficiency improvement control system according to claim 9, characterized in that, The inter-axis coordination triggering module is further configured to: in the pick-up stage, use the Z-axis with the longest time to reach the pick-up stage Z-axis height threshold as a reference to back-calculate the CA-axis triggering time; in the placement stage, use the Z-axis with the shortest time to reach the placement stage Z-axis height threshold as a reference to back-calculate the placement stage CA-axis triggering angle; and output coordination triggering signals to the CA-axis drive mechanism and the lifting axis drive mechanism respectively.

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