A transfer system based on a biomimetic compliant mechanism and a compliant control method for flying crystal spikes.

Abstract

This invention relates to the technical field of chip transfer, specifically to a transfer system based on a biomimetic compliant mechanism and a compliant control method for flying crystal spikes. The transfer system includes a base, a two-dimensional moving device, a first X-axis moving device, and a first Y-axis moving device. The two-dimensional moving device is used to mount Mini LED wafers. The first X-axis moving device is equipped with a support structure, and the first Y-axis moving device is equipped with a two-dimensional compliant flying crystal spike device. The compliant control method includes: when the Mini LED wafer is transferred to the support structure, open-loop feedforward control and contact force semi-closed-loop servo compliant control are used to control the Z-axis movement of the biomimetic compliant mechanism; dual closed-loop high-bandwidth control is used to control the Y-axis movement of the biomimetic compliant mechanism. This invention can eliminate hysteresis effects to address the positioning error problem caused by the mass transfer of Mini LED chips, and improve the transfer accuracy and operational efficiency of flying crystal spikes.

Description

Technical Field

[0001] This invention relates to the technical field of chip transfer, and more specifically, to a transfer system based on a biomimetic compliant mechanism and a method for controlling the compliance of flying crystal spikes. Background Technology

[0002] As a next-generation display technology, Mini LED displays boast excellent contrast and resolution. Mini LED chip packaging is a crucial step. Mechanical Mini LED chip die bonding equipment uses pins to transfer Mini LED chips from the growth substrate to the circuit board. The performance of the pinning mechanism and its controller determines the performance indicators of the Mini LED chip transfer. To ensure accurate positioning between the pinning mechanism and the Mini LED chip, existing technologies utilize biomimetic compliant mechanisms, leveraging biomechanical principles to improve the mechanism's performance and increase operational efficiency. However, the driving mechanism for the flying pinning process still suffers from nonlinear characteristics such as hysteresis and creep, affecting positioning accuracy. Consequently, the consistency and yield of mass Mini LED chip transfer cannot be further improved. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing technologies in the mass transfer of Mini LED chips, which still have positioning errors. It provides a transfer system based on a biomimetic compliant mechanism and a flight crystal piercing compliant control method, which can effectively eliminate hysteresis and creep problems, improve the positioning accuracy of the mass transfer of Mini LED chips, and improve work efficiency.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0005] A transfer system based on a biomimetic compliant mechanism is provided, including a base and a two-dimensional moving device, a first X-axis moving device, and a first Y-axis moving device mounted on the base. The moving end of the two-dimensional moving device is used to mount a MiniLED wafer. The moving end of the first X-axis moving device is provided with a support structure, and the moving end of the first Y-axis moving device is provided with a two-dimensional compliant flying crystal-piercing device. The two-dimensional compliant flying crystal-piercing device includes a biomimetic compliant mechanism, a crystal-piercing mechanism connected to the biomimetic compliant mechanism, and a flight drive mechanism driven by the biomimetic compliant mechanism. The biomimetic compliant mechanism has Y-axis and Z-axis degrees of freedom of movement. A flight displacement sensor is provided on the biomimetic compliant mechanism, and a force sensor is provided on the crystal-piercing mechanism. The system also includes a control device that is communicatively connected to the two-dimensional moving device, the first X-axis moving device, the first Y-axis moving device, the crystal-piercing mechanism, the flight drive mechanism, the flight displacement sensor, and the force sensor.

[0006] This invention provides a transfer system based on a biomimetic compliant mechanism. A first X-axis moving device drives a supporting structure to reciprocate along the X-axis, a first Y-axis moving device drives a two-dimensional compliant flying crystal-piercing device to reciprocate along the Y-axis, and a two-dimensional moving device drives a Mini LED wafer to reciprocate along both the X and Y axes. The Z-axis motion degree of freedom of the biomimetic compliant mechanism is used to transfer the Mini LED wafer to the supporting structure via the crystal-piercing mechanism, and a force sensor can monitor the contact force between the Mini LED wafer and the crystal-piercing mechanism in real time, maintaining the contact force within a preset threshold range. The Y-axis motion degree of freedom of the biomimetic compliant mechanism is used to compensate for displacement differences in the Y-axis direction, and a flight displacement sensor can monitor the Y-axis displacement of the biomimetic compliant mechanism in real time, keeping the crystal-piercing mechanism and the supporting structure relatively stationary, thus achieving alignment of the Mini LED wafer.

[0007] Furthermore, the flight drive mechanism includes a piezoelectric ceramic and a bridge amplification mechanism. The input end of the bridge amplification mechanism is connected to the piezoelectric ceramic, and the output end of the bridge amplification mechanism is connected to the biomimetic compliant mechanism. The piezoelectric ceramic is communicatively connected to the control device through a piezoelectric actuator.

[0008] Furthermore, the first Y-axis moving device includes a gantry, on which a first Y-axis guide rail, a first Y-axis linear motor, and a first Y-axis displacement sensor are connected. A first slide plate is slidably connected to the first Y-axis guide rail. The driving end of the first Y-axis linear motor is connected to the first slide plate, and the fixed end of the flight drive mechanism is connected to the first slide plate. The first Y-axis linear motor and the first Y-axis displacement sensor are both communicatively connected to the control device.

[0009] Furthermore, the two-dimensional moving device includes a second Y-axis moving device and a second X-axis moving device. The second Y-axis moving device is connected to the base via the second X-axis moving device. The moving end of the second Y-axis moving device is used to mount the Mini LED wafer. The second X-axis moving device includes a first mounting base located on both sides of the first X-axis moving device. The first mounting base is connected to the base. A second X-axis linear motor and a second X-axis displacement sensor are mounted on the first mounting base. The driving end of the second X-axis linear motor is connected to the fixed end of the second Y-axis moving device. The second X-axis linear motor, the second X-axis displacement sensor, and the second Y-axis moving device are all communicatively connected to the control device.

[0010] Furthermore, the control device includes a host computer, an industrial control computer communicatively connected to the host computer, and a digital-to-analog converter circuit board and an analog-to-digital converter circuit board communicatively connected to the industrial control computer; the two-dimensional moving device, the first X-axis moving device, and the first Y-axis moving device are all communicatively connected to the industrial control computer, the flight drive mechanism is communicatively connected to the digital-to-analog converter circuit board, and the flight displacement sensor and the force sensor are all communicatively connected to the analog-to-digital converter circuit board.

[0011] This invention also provides a flying crystal-piercing compliance control method for a transfer system based on a biomimetic compliant mechanism, wherein when the two-dimensional compliant flying crystal-piercing device transfers the Mini LED wafer to the support structure:

[0012] The control device employs open-loop feedforward control and semi-closed-loop servo compliant control of contact force to control the Z-axis movement of the bionic compliant mechanism: the force sensor monitors the contact force between the Mini LED wafer and the crystal-piercing mechanism in real time; when the contact force between the two exceeds a preset threshold range, the Z-axis movement speed of the bionic compliant mechanism is reduced until the contact force between the Mini LED wafer and the crystal-piercing mechanism returns to the preset threshold range.

[0013] The control device employs dual closed-loop high-bandwidth control to control the Y-axis motion of the bionic compliant mechanism: let the Y-axis motion speed of the first Y-axis moving device be V1, the Y-axis motion speed of the two-dimensional moving device be V2, and the Y-axis motion speed of the bionic compliant mechanism be V3; the flight displacement sensor monitors the Y-axis motion displacement of the bionic compliant mechanism in real time, and ensures that the Y-axis motion speed satisfies: V1 + V3 = V2.

[0014] This invention also provides a flight crystal-piercing compliant control method for a transfer system based on a biomimetic compliant mechanism. During the Z-axis motion of the biomimetic compliant mechanism, open-loop feedforward control can solve the problem of poor crystal-piercing positioning accuracy caused by hysteresis nonlinearity. By real-time monitoring of the contact force between the Mini LED wafer and the crystal-piercing mechanism, the consistency of mass transfer of Mini LED wafers can be improved. During the Z-axis motion of the biomimetic compliant mechanism, dual closed-loop high-bandwidth control can eliminate the steady-state error of the transfer system and improve the alignment accuracy between the crystal-piercing mechanism and the Mini LED wafer.

[0015] Furthermore, the dual-loop high-bandwidth control includes an inner-loop control with positive position feedback control and an outer-loop control with integral control; wherein, the transfer function of the dual-loop high-bandwidth control is:

[0016]

[0017] The transfer function of the inner loop control is:

[0018]

[0019] The mathematical model for integral control is as follows:

[0020]

[0021] In the formula, G(s) represents the transfer function of the biomimetic compliant mechanism, and C p (s) represents the mathematical model of the positive position feedback control, K i Let represent the integral coefficient, and s represent the complex variable in the Laplace transform.

[0022] Furthermore, the mathematical model for the positive position feedback control is as follows:

[0023]

[0024] In the formula, K p ω represents the gain of positive position feedback control. p Let η represent the natural frequency of the positive position feedback control, s represent the complex variable in the Laplace transform, and η represent the natural frequency of the positive position feedback control. p This represents the damping ratio of the positive position feedback control.

[0025] Furthermore, the transfer function of the biomimetic compliant mechanism is:

[0026]

[0027] In the formula, k represents the low-frequency gain coefficient, ω n Let represent the first natural frequency of the biomimetic compliant mechanism, s represent the complex variable in the Laplace transform, and ξ represent the damping ratio of the biomimetic compliant mechanism.

[0028] Furthermore, the open-loop feedforward function of the open-loop feedforward control is obtained by: obtaining the hysteresis loop of the piezoelectric ceramic of the flight drive mechanism through an open-loop test experiment, fitting the hysteresis loop according to the mathematical model of the hysteresis operator to obtain the hysteresis mathematical model of the piezoelectric ceramic, and then solving the inverse model of the hysteresis mathematical model to obtain the open-loop feedforward function.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] This invention relates to a transfer system based on a biomimetic compliant mechanism and a compliant control method for flying crystal spikes. The Z-axis motion degree of freedom of the biomimetic compliant mechanism in the transfer system is used to transfer Mini LED wafers to the support structure via the crystal spike mechanism. The Y-axis motion degree of freedom of the biomimetic compliant mechanism is used to compensate for the displacement difference in the Y-axis motion, keeping the crystal spike mechanism and the support structure relatively stationary, thus achieving the alignment of the Mini LED wafers. In the Z-axis motion of the biomimetic compliant mechanism, open-loop feedforward control can solve the problem of poor crystal spike positioning accuracy caused by hysteresis nonlinearity. By monitoring the contact force between the Mini LED wafers and the crystal spike mechanism in real time, the consistency of the mass transfer of Mini LED wafers can be improved. In the Z-axis motion of the biomimetic compliant mechanism, dual closed-loop high-bandwidth control can eliminate the steady-state error of the transfer system and improve the alignment accuracy between the crystal spike mechanism and the Mini LED wafers. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the transfer system based on a biomimetic compliant mechanism according to the present invention;

[0032] Figure 2 This is a schematic diagram of the structure of the two-dimensional compliant flying crystal-piercing device of the present invention;

[0033] Figure 3 This is a schematic diagram of the structure of the first X-axis moving device, the first Y-axis moving device, and the supporting structure of the present invention;

[0034] Figure 4 This is a schematic diagram of the structure of the two-dimensional mobile device of the present invention;

[0035] Figure 5 This is a schematic diagram of the communication connection of the transfer system based on the biomimetic compliant mechanism of the present invention;

[0036] Figure 6 This is the Z-axis motion control loop structure of the biomimetic compliant mechanism of the present invention;

[0037] Figure 7 This is the Y-axis motion control loop structure of the biomimetic compliant mechanism of the present invention;

[0038] Figure 8 for Figure 7 The mathematical model.

[0039] In the attached diagram: 100, base; 200, two-dimensional moving device; 210, second Y-axis moving device; 211, second mounting base; 212, second Y-axis guide rail; 213, second Y-axis linear motor; 214, second Y-axis displacement sensor; 215, second sliding plate; 216, second baffle; 220, first mounting base; 230, second X-axis linear motor; 240, second X-axis displacement sensor; 300, first X-axis moving device; 310, first X-axis linear motor; 320, first X-axis displacement sensor; 400, first Y-axis moving device; 410, gantry; 420, first Y-axis guide rail; 430, first Y-axis linear motor; 440, first Y-axis displacement sensor; 450, first sliding plate; 460, first baffle; 500, Mini LED wafer; 600, carrier structure; 610, carrier board; 620, carrier board platform; 700, two-dimensional compliant flying crystal-piercing device; 710, biomimetic compliant mechanism; 720, crystal-piercing mechanism; 721, ejector pin; 722, syringe; 730, flight drive mechanism; 731, piezoelectric ceramic; 732, bridge amplification mechanism; 733, piezoelectric actuator; 740, flight displacement sensor; 750, force sensor; 810, host computer; 820, industrial computer; 830, digital-to-analog converter circuit board; 840, analog-to-digital converter circuit board. Detailed Implementation

[0040] The present invention will be further described below with reference to specific embodiments. The accompanying drawings are for illustrative purposes only, representing schematic diagrams rather than actual physical objects, and should not be construed as limiting the scope of this patent. To better illustrate the embodiments of the present invention, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0041] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0042] Example 1

[0043] like Figures 1 to 5The figure shows an embodiment of a transfer system based on a biomimetic compliant mechanism according to the present invention, including a base 100 and a two-dimensional moving device 200, a first X-axis moving device 300, and a first Y-axis moving device 400 mounted on the base 100. The moving end of the two-dimensional moving device 200 is used to mount a Mini LED wafer 500, the moving end of the first X-axis moving device 300 is provided with a support structure 600, and the moving end of the first Y-axis moving device 400 is provided with a two-dimensional compliant flying crystal-piercing device 700; wherein, the two-dimensional compliant flying crystal-piercing device 700 includes a bionic compliant mechanism 710, a crystal-piercing mechanism 720 connected to the bionic compliant mechanism 710, and a flight drive mechanism 730 drivenly connected to the bionic compliant mechanism 710. The bionic compliant mechanism 710 has motion degrees of freedom in the Y and Z directions. A flight displacement sensor 740 is provided on the bionic compliant mechanism 710, and a force sensor 750 is provided on the crystal-piercing mechanism 720; it also includes a control device that is communicatively connected to the two-dimensional moving device 200, the first X-axis moving device 300, the first Y-axis moving device 400, the crystal-piercing mechanism 720, the flight drive mechanism 730, the flight displacement sensor 740, and the force sensor 750.

[0044] The first X-axis moving device 300 is used to drive the supporting structure 600 to reciprocate along the X-axis, the first Y-axis moving device 400 is used to drive the two-dimensional compliant flying crystal-piercing device 700 to reciprocate along the Y-axis, and the two-dimensional moving device 200 is used to drive the Mini LED wafer 500 to reciprocate along both the X and Y axes. The Z-axis motion degree of freedom of the bionic compliant mechanism 710 is used to transfer the Mini LED wafer 500 to the supporting structure 600 via the crystal-piercing mechanism 720, and can monitor the contact force between the Mini LED wafer 500 and the crystal-piercing mechanism 720 in real time via the force sensor 750, keeping the contact force within a preset threshold range. The Y-axis motion degree of freedom of the bionic compliant mechanism 710 is used to compensate for the displacement difference in the Y-axis motion, and can monitor the Y-axis motion displacement of the bionic compliant mechanism 710 in real time via the flight displacement sensor 740, keeping the crystal-piercing mechanism 720 and the supporting structure 600 relatively stationary, thus achieving the alignment of the Mini LED wafer 500.

[0045] like Figure 2 and Figure 5 As shown, the flight drive mechanism 730 includes a piezoelectric ceramic 731 and a bridge amplification mechanism 732. The input end of the bridge amplification mechanism 732 is connected to the piezoelectric ceramic 731, and the output end of the bridge amplification mechanism 732 is connected to the bionic compliant mechanism 710. The piezoelectric ceramic 731 is communicatively connected to the control device through a piezoelectric actuator 733. In this embodiment, the flight displacement sensor 740 can be a capacitive displacement sensor, and the force sensor 750 can be a force sensor. In this embodiment, the crystal-piercing mechanism 720 includes a pin 721 and a syringe 722. The pin 721 is connected to the bionic compliant mechanism 710 through the syringe 722.

[0046] It should be noted that the biomimetic compliant mechanism 710 is designed based on the biomechanical characteristics of the primitive pigeon. The primitive pigeon exhibits excellent air resistance during flight, reducing energy consumption. Furthermore, compared to other birds, the primitive pigeon has a larger amplitude during wing flapping, making this characteristic applicable to chip transfer in large-stroke Mini LED wafers 500. The biomimetic compliant mechanism 710 includes a crystal-piercing connector and a primitive pigeon wing structure. The wing structure includes sequentially arranged simulated carpal and metacarpal bone beams, simulated forearm beams, simulated humeral bone beams, and simulated scapula beams. Adjacent bone beams are connected by flexible hinges. The simulated carpal and metacarpal bone beams are connected to the crystal-piercing connector via flexible hinges. The crystal-piercing connector is connected to the syringe 722 of the crystal-piercing mechanism 720. The bridge amplification mechanism 732 is prior art and will not be described in detail here. The two-dimensional compliant flying crystal-piercing device 700 has high-precision displacement generation performance. Through the combination of the biomimetic compliant mechanism 710 and the piezoelectric ceramic 731 drive, it can form a displacement generation capability with nanometer-level precision.

[0047] like Figure 3 As shown, the first Y-axis moving device 400 includes a gantry base 410, on which a first Y-axis guide rail 420, a first Y-axis linear motor 430, and a first Y-axis displacement sensor 440 are connected. A first slide plate 450 is slidably connected to the first Y-axis guide rail 420. The drive end of the first Y-axis linear motor 430 is connected to the first slide plate 450, and a bridge amplification mechanism 732 is connected to the first slide plate 450. The first Y-axis linear motor 430 and the first Y-axis displacement sensor 440 are both communicatively connected to a control device. In this embodiment, first baffles 460 are also provided at both ends of the first Y-axis guide rail 420. The first baffles 460 are connected to the gantry base 410, and the first baffles 460 can prevent the first slide plate 450 from detaching from the first Y-axis guide rail 420.

[0048] like Figure 3 and Figure 4 As shown, the first X-axis moving device 300 includes a first X-axis linear motor 310 and a first X-axis displacement sensor 320 mounted on the base 100, and both the first X-axis linear motor 310 and the first X-axis displacement sensor 320 are located below the gantry 410. The supporting structure 600 includes a carrier platform 620 and a carrier plate 610 mounted on the carrier platform 620. The carrier platform 620 is connected to the drive end of the first X-axis linear motor 310, and the carrier plate 610 is located below the crystal-piercing mechanism 720.

[0049] like Figure 4As shown, the two-dimensional moving device 200 includes a second Y-axis moving device 210 and a second X-axis moving device. The second Y-axis moving device 210 is connected to the base 100 via the second X-axis moving device. The moving end of the second Y-axis moving device 210 is used to mount the Mini LED wafer 500. The second X-axis moving device includes a first mounting base 220 located on both sides of the first X-axis moving device 300. The first mounting base 220 is connected to the base 100. A second X-axis linear motor 230 and a second X-axis displacement sensor 240 are mounted on the first mounting base 220. The driving end of the second X-axis linear motor 230 is connected to the fixed end of the second Y-axis moving device 210. The second X-axis linear motor 230, the second X-axis displacement sensor 240, and the second Y-axis moving device 210 are all communicatively connected to the control device.

[0050] In this embodiment, the second Y-axis moving device 210 has a structure similar to the first Y-axis moving device 400. The second Y-axis moving device 210 includes a second mounting base 211, a second Y-axis guide rail 212, a second Y-axis linear motor 213, a second Y-axis displacement sensor 214, a second sliding plate 215, and a second baffle 216. The second mounting base 211 is connected to the drive end of the second X-axis linear motor 230. The second Y-axis guide rail 212, the second Y-axis linear motor 213, and the second Y-axis displacement sensor 214 are all mounted on the second mounting base 211. The Mini LED wafer 500 is mounted on the second sliding plate 215. The second Y-axis linear motor 213 can drive the Mini LED wafer 500 to move along the second Y-axis guide rail 212, and the second Y-axis displacement sensor 214 can monitor the movement displacement of the Mini LED wafer 500. In this embodiment, the Mini LED wafer 500 is located between the crystal-piercing mechanism 720 and the carrier plate 610.

[0051] In this embodiment, the first Y-axis displacement sensor 440, the first X-axis displacement sensor 320, the second X-axis displacement sensor 240, and the second Y-axis displacement sensor 214 can all be optical grating rulers.

[0052] like Figure 5 As shown, the control device includes a host computer 810, an industrial control computer 820 that is communicatively connected to the host computer 810, and a digital-to-analog converter circuit board 830 and an analog-to-digital converter circuit board 840 that are communicatively connected to the industrial control computer 820. The first Y-axis linear motor 430, the first Y-axis displacement sensor 440, the first X-axis linear motor 310, the first X-axis displacement sensor 320, the second Y-axis linear motor 213, the second Y-axis displacement sensor 214, the second X-axis linear motor 230, and the second X-axis displacement sensor 240 are all communicatively connected to the industrial control computer 820. The piezoelectric actuator 733 is communicatively connected to the digital-to-analog converter circuit board 830. The flight displacement sensor 740 and the force sensor 750 are both communicatively connected to the analog-to-digital converter circuit board 840.

[0053] The working principle of the transfer system based on a biomimetic compliant mechanism of the present invention is as follows:

[0054] The first X-axis moving device 300 can move the supporting structure 600 to directly below the Mini LED wafer 500. The two-dimensional moving device 200 can move the Mini LED wafer 500 in the X and Y directions. The first Y-axis moving device 400 and the bionic compliant mechanism 710 can move the crystal-piercing mechanism 720 in the Y direction. The bionic compliant mechanism 710 can also move the crystal-piercing mechanism 720 in the Z direction and perform crystal piercing. During the movement of the crystal-piercing mechanism 720, the force sensor 750 can monitor the contact force between the Mini LED wafer 500 and the crystal-piercing mechanism 720 in real time, and then maintain the contact force within a preset threshold range through the control of the control device. The displacement sensor 740 can monitor the Y-axis displacement of the bionic compliant mechanism 710 in real time, and then keep the crystal-piercing mechanism 720 and the supporting structure 600 relatively stationary through the control of the control device, thereby achieving the alignment of the Mini LED wafer 500.

[0055] Example 2

[0056] This embodiment is the first embodiment of a flight crystal-piercing compliance control method for a transfer system based on a biomimetic compliant mechanism according to the present invention. The method includes: when the two-dimensional compliant flight crystal-piercing device 700 transfers the Mini LED wafer 500 to the support structure 600:

[0057] The control device adopts open-loop feedforward control and contact force semi-closed-loop servo compliant control to control the Z-axis movement of the bionic compliant mechanism 710: the force sensor 750 monitors the contact force between the Mini LED wafer 500 and the crystal-piercing mechanism 720 in real time. When the contact force between the two is greater than the preset threshold range, the Z-axis movement speed of the bionic compliant mechanism 710 is reduced until the contact force between the Mini LED wafer 500 and the crystal-piercing mechanism 720 is restored to the preset threshold range.

[0058] The control device adopts dual closed-loop high-bandwidth control to control the Y-axis motion of the bionic compliant mechanism 710: let the Y-axis motion speed of the first Y-axis moving device 400 be V1, the Y-axis motion speed of the two-dimensional moving device 200 be V2, and the Y-axis motion speed of the bionic compliant mechanism 710 be V3; the flight displacement sensor 740 monitors the Y-axis motion displacement of the bionic compliant mechanism 710 in real time and ensures that the Y-axis motion speed satisfies: V1 + V3 = V2.

[0059] In the Z-axis motion of the biomimetic compliant mechanism 710, the problem of poor crystal-piercing positioning accuracy caused by hysteresis nonlinearity can be solved by open-loop feedforward control. By monitoring the contact force between the Mini LED wafer 500 and the crystal-piercing mechanism 720 in real time, the consistency of the mass transfer of the Mini LED wafer 500 can be improved. In the Z-axis motion of the biomimetic compliant mechanism 710, the steady-state error of the transfer system can be eliminated by dual closed-loop high-bandwidth control, thereby improving the alignment accuracy between the crystal-piercing mechanism 720 and the Mini LED wafer 500.

[0060] Example 3

[0061] This embodiment is the second embodiment of the flight spike compliance control method for a transfer system based on a biomimetic compliant mechanism according to the present invention. This embodiment is similar to embodiment two, such as... Figures 6 to 8 As shown, the difference lies in:

[0062] According to the control algorithm requirements of the host computer 810, the industrial control computer 820 outputs an analog voltage through the analog-to-digital converter circuit board 830 to control the output voltage of the piezoelectric driver 733. The piezoelectric driver 733 amplifies the control voltage and outputs it to the piezoelectric ceramic 731. The piezoelectric ceramic 731 outputs displacement according to the control voltage. The output displacement of the piezoelectric ceramic 731 is amplified by the bridge amplification mechanism 732 and then output to the bionic compliant mechanism 710. The bionic compliant mechanism 710 drives the crystal-piercing mechanism 720 to move. During the movement of the crystal-piercing mechanism 720:

[0063] The host computer 810 controls the Z-axis motion of the bionic compliant mechanism 710 based on open-loop feedforward control and semi-closed-loop servo compliant control of contact force: the force sensor monitors the contact force between the Mini LED wafer 500 and the crystal-piercing mechanism 720 in real time, and transmits the contact signal to the industrial computer 820 through the analog-to-digital converter circuit board 840. When the contact force between the two is greater than a preset threshold range, the Z-axis motion speed of the bionic compliant mechanism 710 is reduced until the contact force between the Mini LED wafer 500 and the crystal-piercing mechanism 720 returns to the preset threshold range. Specifically, when the contact force F > 0.3N, the Z-axis motion speed of the bionic compliant mechanism 710 is reduced; when the contact force F ≤ 0.3N, the Z-axis motion speed of the bionic compliant mechanism 710 continues to increase.

[0064] The host computer 810 controls the Y-axis motion of the bionic compliant mechanism 710 based on dual closed-loop high-bandwidth control: Let the Y-axis motion speed of the first Y-axis moving device 400 be V1, the Y-axis motion speed of the second Y-axis moving device 210 be V2, and the Y-axis motion speed of the bionic compliant mechanism 710 be V3; the capacitive displacement sensor monitors the Y-axis motion displacement of the bionic compliant mechanism 710 in real time and ensures that the Y-axis motion speed satisfies: V1 + V3 = V2.

[0065] Among them, such as Figures 6 to 8 As shown, the dual-loop high-bandwidth control includes an inner-loop control with positive position feedback control and an outer-loop control with integral control; the transfer function of the dual-loop high-bandwidth control is:

[0066]

[0067] The transfer function for the inner loop control is:

[0068]

[0069] The mathematical model for integral control is as follows:

[0070]

[0071] In the formula, G(s) represents the transfer function of the bionic compliant mechanism 710, and C p (s) represents the mathematical model of positive position feedback control, K i K represents the integral coefficient. i It can be obtained through parameter tuning, where s represents the complex variable in the Laplace transform.

[0072] Specifically, the mathematical model for positive position feedback control is:

[0073]

[0074] In the formula, K p ω represents the gain of positive position feedback control. p Let η represent the natural frequency of the positive position feedback control, s represent the complex variable in the Laplace transform, and η represent the natural frequency of the positive position feedback control. p This represents the damping ratio of the positive position feedback control.

[0075] Specifically, the transfer function of the bionic compliant mechanism 710 is:

[0076]

[0077] In the formula, k represents the low-frequency gain coefficient, ω n Let denot represent the first natural frequency of the bionic compliant mechanism 710, s represent the complex variable in the Laplace transform, and ξ represent the damping ratio of the bionic compliant mechanism 710.

[0078] Specifically, due to the "low damping" and "low natural frequency" characteristics of the biomimetic compliant mechanism 710, the bandwidth frequency of the transfer system will be less than 10% of the first-order natural frequency when closed-loop control is used. However, in this invention, inner-loop control can be used to improve the equivalent damping and equivalent natural frequency of the transfer system. That is, using a positive position feedback control algorithm, the biomimetic compliant mechanism 710 can be considered as a second-order underdamped system, and its transfer function can be expressed as... It should be noted that the transfer function of the biomimetic compliant mechanism 710 can be obtained through system identification. The mathematical model of positive position feedback control can be expressed as follows: Among them, the design parameter K p ω p η p This can be achieved through optimization algorithm tuning. Positive position feedback control can maximize the closed-loop bandwidth of the transfer system while ensuring control stability and sufficient phase margin. The transfer function of the inner-loop control can be expressed as follows: Positive position feedback control can effectively increase the closed-loop bandwidth frequency of the transfer system, thereby improving the alignment speed during the die bonding process. To address the alignment accuracy issue in the Y-axis of the biomimetic compliant mechanism 710, this invention also employs outer-loop control—that is, adding a negative feedback control to the inner-loop control—to eliminate steady-state errors in the transfer system and improve positioning accuracy. To achieve the above functions, this invention adds integral control to the outer-loop control to improve the type of the closed-loop system and reduce steady-state errors. Therefore, the open-loop transfer function of the dual-closed-loop high-bandwidth control is: The transfer function of the dual-loop high-bandwidth control is:

[0079]

[0080] Specifically, the open-loop feedforward function of the open-loop feedforward control is obtained as follows: the hysteresis loop of the piezoelectric ceramic 731 is obtained through open-loop test experiments, and the hysteresis mathematical model of the piezoelectric ceramic 731 is obtained by fitting the hysteresis loop according to the mathematical model of the Prandtl-Ishlinskii hysteresis operator. Then, the inverse model of the hysteresis mathematical model is solved to obtain the open-loop feedforward function.

[0081] This invention discloses a compliant control method for a transfer system based on a biomimetic compliant mechanism. This method offers advantages such as high bandwidth, compliance, and flight capability. When the contact force between the ejector pin 721 and the Mini LED wafer 500 chip is excessive during the chip insertion process, the piezoelectric drive voltage is reduced to prevent the Mini LED wafer 500 chip from being affected by excessive contact force, thus ensuring consistent transfer. Addressing the issues of low bandwidth in the biomimetic compliant mechanism 710 and the hysteresis effect of the piezoelectric ceramic 731, this invention combines high-bandwidth control with compliant control to effectively eliminate the hysteresis effect of the piezoelectric ceramic 731 and improve the closed-loop control bandwidth.

[0082] In the specific implementation of the above embodiments, the technical features can be combined in any non-contradictory way. For the sake of brevity, not all possible combinations of the above technical features are described. However, as long as the combination of these technical features is not contradictory, it should be considered to be within the scope of this specification.

[0083] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A transfer system based on a biomimetic compliant mechanism, characterized in that, The device includes a base (100) and a two-dimensional moving device (200), a first X-axis moving device (300), and a first Y-axis moving device (400) mounted on the base (100). The moving end of the two-dimensional moving device (200) is used to mount a Mini LED wafer (500). The moving end of the first X-axis moving device (300) is provided with a support structure (600), and the moving end of the first Y-axis moving device (400) is provided with a two-dimensional compliant flying crystal-piercing device (700). The two-dimensional compliant flying crystal-piercing device (700) includes a biomimetic compliant mechanism (710), a crystal-piercing mechanism (720) connected to the biomimetic compliant mechanism (710), and a flight drive mechanism (730) driven by the biomimetic compliant mechanism (710). The compliant mechanism (710) has Y-axis and Z-axis motion degrees of freedom. The bionic compliant mechanism (710) is provided with a flight displacement sensor (740), and the crystal-piercing mechanism (720) is provided with a force sensor (750). It also includes a control device that is communicatively connected to the two-dimensional moving device (200), the first X-axis moving device (300), the first Y-axis moving device (400), the crystal-piercing mechanism (720), the flight drive mechanism (730), the flight displacement sensor (740), and the force sensor (750). The two-dimensional moving device (200) includes a second Y-axis moving device (210) and a second X-axis moving device. The second Y-axis moving device (210) is connected to the base (100) through the second X-axis moving device. The moving end of the second Y-axis moving device (210) is used to mount the Mini LED wafer (500). The second X-axis moving device includes a first mounting base (220) located on both sides of the first X-axis moving device (300). The first mounting base (220) is connected to the base (100). A second X-axis linear motor (230) and a second X-axis displacement sensor (240) are mounted on the first mounting base (220). The driving end of the second X-axis linear motor (230) is connected to the fixed end of the second Y-axis moving device (210). The second X-axis linear motor (230), the second X-axis displacement sensor (240), and the second Y-axis moving device (210) are all communicatively connected to the control device. The control device includes a host computer (810), an industrial control computer (820) communicatively connected to the host computer (810), and a digital-to-analog converter circuit board (830) and an analog-to-digital converter circuit board (840) communicatively connected to the industrial control computer (820). The two-dimensional moving device (200), the first X-axis moving device (300), and the first Y-axis moving device (400) are all communicatively connected to the industrial control computer (820). The flight drive mechanism (730) is communicatively connected to the digital-to-analog converter circuit board (830). The flight displacement sensor (740) and the force sensor (750) are all communicatively connected to the analog-to-digital converter circuit board (840).

2. The transfer system based on a biomimetic compliant mechanism according to claim 1, characterized in that, The flight drive mechanism (730) includes a piezoelectric ceramic (731) and a bridge amplification mechanism (732). The input end of the bridge amplification mechanism (732) is connected to the piezoelectric ceramic (731), and the output end of the bridge amplification mechanism (732) is connected to the bionic compliant mechanism (710). The piezoelectric ceramic (731) is communicatively connected to the control device through a piezoelectric actuator (733).

3. The transfer system based on a biomimetic compliant mechanism according to claim 1, characterized in that, The first Y-axis moving device (400) includes a gantry (410), on which a first Y-axis guide rail (420), a first Y-axis linear motor (430), and a first Y-axis displacement sensor (440) are connected. A first slide plate (450) is slidably connected to the first Y-axis guide rail (420). The driving end of the first Y-axis linear motor (430) is connected to the first slide plate (450), and the fixed end of the flight drive mechanism (730) is connected to the first slide plate (450). The first Y-axis linear motor (430) and the first Y-axis displacement sensor (440) are both communicatively connected to the control device.

4. A method for flight crystal compliance control applied to a transfer system based on a biomimetic compliant mechanism as described in any one of claims 1 to 3, characterized in that, When the two-dimensional compliant flying crystal-piercing device (700) transfers the Mini LED wafer (500) to the support structure (600): The control device adopts open-loop feedforward control and contact force semi-closed-loop servo compliant control to control the Z-axis movement of the bionic compliant mechanism (710): the force sensor (750) monitors the contact force between the Mini LED wafer (500) and the crystal-piercing mechanism (720) in real time. When the contact force between the two is greater than the preset threshold range, the Z-axis movement speed of the bionic compliant mechanism (710) is reduced until the contact force between the Mini LED wafer (500) and the crystal-piercing mechanism (720) is restored to the preset threshold range. The control device adopts dual closed-loop high-bandwidth control to control the Y-axis movement of the bionic compliant mechanism (710): let the Y-axis movement speed of the first Y-axis moving device (400) be V1, the Y-axis movement speed of the two-dimensional moving device (200) be V2, and the Y-axis movement speed of the bionic compliant mechanism (710) be V3; the flight displacement sensor (740) monitors the Y-axis movement displacement of the bionic compliant mechanism (710) in real time, and makes the Y-axis movement speed satisfy: V1 + V3 = V2; The dual-loop high-bandwidth control includes an inner-loop control with positive position feedback control and an outer-loop control with integral control; wherein the transfer function of the dual-loop high-bandwidth control is: ； The transfer function of the inner loop control is: ； The mathematical model for integral control is as follows: ； In the formula, The transfer function of the biomimetic compliant mechanism (710) is represented. This represents the mathematical model of the positive position feedback control. Represents the integral coefficient. s Represent the complex variables in the Laplace transform; The mathematical model for the positive position feedback control is as follows: ； In the formula, K p This represents the gain of the positive position feedback control. ω p This represents the natural frequency of the positive position feedback control. s Denotes the complex variable in the Laplace transform. η p This indicates the damping ratio for positive position feedback control; The transfer function of the biomimetic compliant mechanism (710) is: ； In the formula, k This represents the low-frequency gain coefficient. This represents the first natural frequency of the biomimetic compliant mechanism (710). s Denotes the complex variable in the Laplace transform. The damping ratio of the biomimetic compliant mechanism (710) is indicated.

5. The flight spike compliance control method according to claim 4, characterized in that, The method for obtaining the open-loop feedforward function of the open-loop feedforward control is as follows: the hysteresis loop of the piezoelectric ceramic (731) of the flight drive mechanism (730) is obtained through an open-loop test experiment, and the hysteresis mathematical model of the piezoelectric ceramic (731) is obtained by fitting the hysteresis loop according to the mathematical model of the hysteresis operator, and then the inverse model of the hysteresis mathematical model is solved to obtain the open-loop feedforward function.

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