An automatic zoom lens control system and method

Abstract

The application discloses an automatic zoom lens control system and method, and belongs to the technical field of semiconductor packaging test automation equipment. The lens module comprises a lens structure assembly and a motor structure assembly. The lens structure assembly comprises a lens, and the motor structure assembly comprises a rotor, a coil and a stator. The rotor, the coil and the lens are rigidly connected together and simultaneously perform axial movement. The control module comprises an industrial computer, a motion control card and a driver. The motion control card and the driver are respectively in communication connection with the industrial computer. The motion control card is used for executing motor motion planning and calculating position loop improved two-order linear active disturbance rejection controller output. The automatic zoom lens control system and method can obtain clear images of chips at different heights on a welding part by controlling automatic zoom of the lens, and can ensure high precision of the zoom device and fast automatic zoom speed.

Description

Technical Field

[0001] This application belongs to the technical field of semiconductor packaging and testing automation equipment, specifically relating to an automatic zoom lens control system and method. Background Technology

[0002] In the field of semiconductor packaging and testing, wire bonders are core equipment for achieving electrical connections between chips and external circuits. The bonding process requires the wire bonder's vision system to acquire clear images of the workpiece in order to locate the accurate bonding target. Its bonding accuracy directly depends on the vision system's precise identification of solder joints (such as chip pins and pads).

[0003] However, existing wire bonding machine vision systems have the following technical shortcomings:

[0004] Traditional solutions use manual focusing to a fixed focal length for image recognition, which is only suitable for scenarios where the surface height of the solder joints is strictly coplanar, i.e., the solder wire heights are on the same horizontal plane. When the package contains multiple stacked chips, substrate warping, or pin step differences, the same plane cannot cover all the solder joints. That is, when the chip lead heights on the solder joint are not on the same plane, it leads to blurred images in some areas, severely reducing the soldering positioning accuracy.

[0005] Although some devices have attempted to introduce automatic zoom technology, such as automatic zoom schemes using mechanical transmission, i.e., automatic zoom schemes using mechanical transmission of stepper motors and gear sets, they cannot simultaneously meet the requirements of speed and accuracy due to mechanical delays. Summary of the Invention

[0006] To address the problems in related technologies, namely the inability of traditional manual focusing to adapt to non-planar chips and the shortcomings of existing automatic zoom solutions in terms of speed and accuracy, this application provides an automatic zoom lens control system and method that achieves automatic zoom while ensuring high accuracy and fast automatic zoom speed.

[0007] The technical solution is as follows:

[0008] On the one hand, an automatic zoom lens control system is provided, comprising:

[0009] The lens module includes a lens structure assembly and a motor structure assembly. The lens structure assembly includes a lens lens, and the motor structure assembly includes a mover, a frame fixedly connected to the mover, a coil fixedly connected to the frame, and a stator fixed on the base of the lens structure assembly. The mover, the coil, and the lens lens are rigidly connected together and move axially at the same time.

[0010] The control module includes an industrial computer, a motion control card embedded in the industrial computer, and a driver. The motion control card and the driver are respectively connected to the industrial computer for communication. The motion control card is used to execute motor motion planning and output the position loop improvement of the second-order linear active disturbance rejection device. The driver is used to receive the control signal from the motion control card and convert it into a corresponding current to drive the motor motion.

[0011] Furthermore, it employs a position loop-improved two-order linear active disturbance rejection controller, which includes a linear extended state observer and a linear state error feedback control law. The expression for the improved two-order linear extended state observer is as follows:

[0012]

[0013] In the formula, For observer parameters, For feedback speed, Identify parameters for the motor. For the final output of the controller, This is the estimated total disturbance.

[0014] The expression for the linear state error feedback control law is:

[0015]

[0016] In the formula, k 1 , k 2 This is the gain coefficient. For position commands, This is the feedback location.

[0017] Furthermore, the motion control card communicates with the industrial computer via the PCIe protocol.

[0018] Furthermore, the motion control card plans an S-shaped motion curve based on the target focal length command and the current position feedback of the mover, and calculates the output of the position loop improved second-order linear active disturbance rejection controller.

[0019] Furthermore, the target focal length command is generated by the host computer based on the image clarity of the welding area acquired in real time.

[0020] Furthermore, the motor structure assembly is also equipped with a position sensor, one end of which is fixedly connected to the stator and the other end of which is fixedly connected to the mover, for real-time monitoring of the axial position of the lens.

[0021] Furthermore, the motor structure assembly is also provided with a return spring connected to the mover.

[0022] Furthermore, the motor structure component is a voice coil motor.

[0023] Furthermore, the lens is a zoom lens.

[0024] On the other hand, an automatic zoom lens control method is provided, wherein the automatic zoom lens control system described above includes:

[0025] The host computer generates a target focal length command based on the real-time image clarity of the welding area.

[0026] The motion control card plans the motion curve based on the target focal length command and the current position feedback of the mover;

[0027] The motion control card is based on a position loop-based improved second-order linear active disturbance rejection controller, which calculates the controller output and sends control signals to the driver.

[0028] The driver receives the control signal sent by the motion control card, converts it into a corresponding current to drive the motor and move the lens.

[0029] The position sensor transmits the feedback position of the motor mover to the motion controller until the voice coil motor moves to the commanded position.

[0030] The technical solution includes at least the following technical effects:

[0031] 1. Using the control system of this application, the position error of the motor running at an acceleration of less than 20g can be adjusted to within 10 micrometers within 2 milliseconds after the end of the motion command, while the adjustment time for the same motion using traditional technology is generally more than 5 milliseconds. The control system of this application can help the lens to zoom quickly and accurately, ensuring clear imaging of the non-planar chip across the entire field of view.

[0032] 2. The improved two-order linear active disturbance rejection control algorithm designed not only ensures the positioning accuracy of the motor, but also has a strong ability to resist external disturbances. For example, when the Y-shaped moving body moves, it brings a large impact force to the voice coil motor of the lens module. The improved linear observer can observe this disturbance and compensate for it in the linear state error feedback control law, thereby reducing the impact of external disturbances on the voice coil motor.

[0033] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description

[0034] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0035] Figure 1 This is a schematic diagram of the structure of a lens module provided in a preferred embodiment of this application;

[0036] Figure 2 This is a schematic diagram of the structure of a motor module provided in a preferred embodiment of this application;

[0037] Figure 3 for Figure 2 A sectional view along direction A.

[0038] Figure 4 A control flowchart of a control module provided in a preferred embodiment of this application;

[0039] Explanation of reference numerals in the attached figures:

[0040] 1. Coil; 2. Stator; 3. Lens; 4. Mover; 5. Position sensor; 6. Spring structure; 7. Lens structure assembly; 8. Motor structure assembly; 9. Host computer; 10. Motion control card; 11. Driver. Detailed Implementation

[0041] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0042] This application provides an automatic zoom lens control system including a lens module and a control module. It is applicable to automated semiconductor packaging and testing equipment, specifically relating to high-precision real-time automatic focusing control technology for wire bonding machine vision systems.

[0043] The lens module includes a lens structure assembly 7 and a motor structure assembly 8. The lens structure assembly 7 includes a lens 3, and the motor structure assembly 8 includes a mover 4, a coil 1 connected to the mover 4, and a stator 2 fixed on the base of the lens structure assembly 7. The mover 4, the coil 1, and the lens 3 are rigidly connected together and move axially at the same time.

[0044] The control module includes an industrial computer, a motion control card 10 embedded in the industrial computer, and a driver 11. The motion control card 10 and the driver 11 are respectively connected to the industrial computer. The motion control card 10 is used to execute the motion planning of the motor structure component 8 and the improved two-order linear active disturbance rejection control algorithm. The driver 11 is used to receive the control signals from the motion control card 10 and convert them into corresponding current to drive the motor structure component 8 to move.

[0045] The automatic zoom lens control system provided in this application enables the camera to acquire clear images of chips at different heights on the soldered parts by controlling the lens to automatically zoom. While achieving automatic zoom, it also ensures high precision and fast speed of the zoom device.

[0046] Example 1

[0047] like Figures 1-3 As shown, in this embodiment, the lens module includes a lens 3 and a motor structure assembly 8. Optionally, the motor structure assembly 8 is a voice coil motor, and the lens 3 is a zoom lens.

[0048] like Figure 1 , Figure 3 As shown, the stator 2 of the motor (i.e., the stator magnet) is fixed to the base of the lens structure assembly 7. The lens 3 is fixedly installed inside the mover 4 of the motor and moves axially along with the mover 4, achieving optical path zoom and changing the depth of field. The coil 1 is fixed to the cylindrical frame, which is fixedly connected to the mover 4. The lens 3 is fixedly installed on the mover 4. The mover 4 of the motor, the coil 1, and the lens 3 are rigidly connected together and move axially simultaneously, in the direction of motion as shown. Figure 3 The arrow next to the moving part 4 points in the straight line direction. The stator 2 and the coil 1 generate a magnetic field that drives the frame to move. The frame is fixedly connected to the moving part 4, thus driving the moving part 4 to move, which in turn drives the lens 3 fixed on the moving part to move axially. The hardware integrates a voice coil motor to directly drive the lens 3. The moving part 4, coil 1, and lens 3 are rigidly connected, reducing transmission errors.

[0049] like Figure 3 As shown, one end of the position sensor 5 is fixed to the stator 2, and the other end is fixed to the mover 4. The position sensor 5 realizes real-time detection of the mover position and feeds it back to the control system. The spring structure 6 is connected to the mover 4 to help the mover 4 quickly reset when it is enabled. The spring structure 6 is a reset spring.

[0050] The hardware components of the control module include an industrial computer, a motion control card 10, and a driver 11. The motion control card is embedded in the industrial computer and connects and communicates with it via the PCIe protocol. The motion planning of the motor structure component 8 and the improved second-order linear active disturbance rejection control algorithm are both completed in the motion control card. The driver 11 receives the control signals from the motion control card and converts them into corresponding currents to drive the motor structure component 8 to move.

[0051] Voice coil motors are second-order systems, and are typically controlled by third-order linear active disturbance rejection controllers. However, position sensors can collect position information in real time, and feedback speed can also be obtained through feedback position difference. Therefore, in this application embodiment, a position loop improved second-order linear active disturbance rejection controller is designed.

[0052] The reduced-order linear active disturbance rejection controller (ADC) consists of a linear extended state observer and a linear state error feedback control law. The reduced-order linear extended state observer only observes the total disturbance, and its expression is:

[0053] (1)

[0054] In the formula, This is the estimated total system disturbance. β For observer parameters, For feedback acceleration, b 0 Identify parameters for the motor. This represents the final output of the controller. Feedback acceleration is included in the formula. , The accuracy is greatly affected by hardware precision, such as a position sensor precision of 1µm / count, a system sampling frequency of 10000Hz, and a unit feedback acceleration of 1 count / sample. 2 After conversion to SI units, it is 100 m / s 2 To improve the accuracy of feedback acceleration, a higher resolution position sensor or a motion control card with a higher sampling frequency is required, which will greatly increase the hardware cost. Integrating both sides of equation (1), the improved expression for the reduced-order linear extended state observer is obtained as follows:

[0055] (2)

[0056] In the formula, the improved observer feedback acceleration After points are added, the feedback speed is converted. , It is less affected by hardware accuracy, thus improving the accuracy of the total disturbance estimate z.

[0057] The designed linear state error feedback control law is expressed as follows:

[0058] (3)

[0059] In the formula, k 1 and k 2 It is the gain coefficient. For position commands, This is the feedback location.

[0060] The control algorithm uses a position loop-improved second-order linear active disturbance rejection controller, which has higher observer accuracy than the traditional linear active disturbance rejection controller and stronger resistance to external disturbances than the traditional PID controller. It can simultaneously have the ability to quickly locate and strongly resist disturbances.

[0061] During the welding process, the host computer 9 calculates the target focal length based on the real-time image clarity of the welding area and sends a motion command to the motion control card 10. The motion control card 10 plans the motion command based on the feedback position of the current motor mover 4 and the command position, that is, plans the S-shaped motion curve and calculates the output of the improved second-order linear active disturbance rejection controller. The driver 11 receives the control signal from the motion control card and converts it into a corresponding current to drive the motor structure component 8 to move. The position sensor 5 feeds back the motor position to the motion control card 10, forming a control closed loop until the motor structure component 8 moves to the command position.

[0062] The control system of this application embodiment can adjust the position error to within 10 micrometers within 2 milliseconds after the motor accelerates to within 20g. In contrast, the adjustment time for the same movement using conventional control systems is generally more than 5 milliseconds. Therefore, it can be seen that the control system of this application embodiment achieves millisecond-level rapid adjustment after the motor movement ends, and micrometer-level precise positioning, which helps the lens to zoom quickly and accurately. Therefore, the control system of this application can help the lens zoom quickly and accurately, ensuring clear imaging of the entire field of view of the non-planar chip.

[0063] Example 2

[0064] like Figure 4 As shown, an automatic zoom lens control method is provided, and the specific steps are as follows:

[0065] The host computer 9 generates a target focal length command based on the image clarity of the welding area acquired in real time.

[0066] The motion control card 10 plans the motion curve based on the target focal length command and the current position feedback of the mover 4;

[0067] The motion control card 10 is a two-order linear active disturbance rejection controller based on the improved position loop, which calculates the output of the position loop and sends the control signal to the driver 11.

[0068] The driver 11 receives the control signal sent by the motion control card 10 and converts it into a corresponding current to drive the motor structure component 8 to move the lens 3.

[0069] Position sensor 5 transmits the feedback position of mover 4 to motion controller until voice coil motor moves to the commanded position.

[0070] It should be noted that the host computer is software, while the industrial control computer is hardware similar to a computer host.

[0071] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

Claims

1. An automatic zoom lens control system, characterized in that, include: The lens module includes a lens structure assembly and a motor structure assembly. The lens structure assembly includes a lens lens, and the motor structure assembly includes a mover, a frame fixedly connected to the mover, a coil fixedly connected to the frame, and a stator fixed on the base of the lens structure assembly. The mover, the coil, and the lens lens are rigidly connected together and move axially at the same time. The control module includes an industrial computer, a motion control card embedded in the industrial computer, and a driver. The motion control card and the driver are respectively connected to the industrial computer for communication. The motion control card is used to execute motor motion planning and calculate the output of the second-order linear active disturbance rejection controller. The driver is used to receive the control signals from the motion control card and convert them into corresponding current to drive the motor motion. The reduced-order linear active disturbance rejection controller includes a linear extended state observer and a linear state error feedback control law. The expression for the linear extended state observer is: ； In the formula, For observer parameters, For feedback speed, Identify parameters for the motor. For the final output of the controller, This is the estimated total disturbance. The expression for the linear state error feedback control law is: ； In the formula, k 1 , k 2 This is the gain coefficient. For position commands, Identify parameters for the motor. This is the feedback location.

2. The automatic zoom lens control system according to claim 1, characterized in that, The motion control card communicates with the industrial computer via the PCIe protocol.

3. The automatic zoom lens control system according to claim 2, characterized in that, The motion control card plans an S-shaped motion curve and calculates the controller output based on the target focal length command and the current position feedback of the mover.

4. The automatic zoom lens control system according to claim 3, characterized in that, The target focal length command is generated by the industrial control computer based on the image clarity of the welding area acquired in real time.

5. The automatic zoom lens control system according to claim 1, characterized in that, The motor structure assembly is also equipped with a position sensor, one end of which is fixedly connected to the stator and the other end of which is fixedly connected to the mover, for real-time monitoring of the axial displacement of the lens.

6. The automatic zoom lens control system according to claim 1, characterized in that, The motor structure assembly is also provided with a return spring connected to the mover.

7. The automatic zoom lens control system according to claim 1, characterized in that, The motor structure component is a voice coil motor.

8. The automatic zoom lens control system according to claim 1, characterized in that, The lens is a zoom lens.

9. An automatic zoom lens control method, employing the automatic zoom lens control system described in any one of claims 1-8, characterized in that, include: The host computer generates a target focal length command based on the real-time image clarity of the welding area. The motion control card plans an S-shaped motion curve based on the target focal length command and the current position feedback of the mover; The motion control card is based on a second-order linear active disturbance rejection controller, which calculates the controller output and sends control signals to the driver. The driver receives the control signal sent by the motion control card, converts it into a corresponding current to drive the motor and move the lens. The position sensor transmits the feedback position of the motor mover to the motion controller until the voice coil motor moves to the commanded position.

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