Transfer system based on bionic compliant mechanism and flight thorn crystal compliant control method

Abstract

The invention relates to the technical field of chip transfer, in particular to a transfer system based on a bionic compliant mechanism and a flight thorn crystal compliant control method.The transfer system comprises a base, a two-dimensional moving device, a first X-direction moving device and a first Y-direction moving device, the two-dimensional moving device is used for installing a Mini LED wafer, the first X-direction moving device is provided with a bearing structure, and the first Y-direction moving device is provided with a second X-direction moving device; the first Y-direction moving device is provided with a two-dimensional compliant flight crystal pricking device; the compliant control method comprises the following steps: when a Mini LED wafer is transferred to a bearing structure, adopting open-loop feedforward control and contact force semi-closed-loop servo compliant control to control Z-direction movement of a bionic compliant mechanism; and the Y-direction movement of the bionic compliant mechanism is controlled by adopting double-closed-loop high-bandwidth control. According to the invention, the hysteresis effect can be eliminated so as to deal with the positioning error problem caused by the huge transfer of the Mini LED chip, and the transfer precision and the operation efficiency of the flying thorn crystal are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of chip transfer, and more specifically, to a transfer system based on a bionic compliant mechanism and a compliant control method for a flying spike crystal. Background Art

[0002] As a new generation of display technology, Mini LED display screens have good contrast and resolution. Among them, MiniLED chip packaging is a key link. Mechanical Mini LED chip bonding equipment can transfer MiniLED chips from the growth substrate to the circuit substrate by means of a pin piercing. The performance of the piercing mechanism and its controller determines the performance indicators of the Mini LED chip transfer. In order to enable accurate positioning between the piercing mechanism and the Mini LED chip, the prior art uses a bionic compliant mechanism to improve the performance indicators of the mechanism itself and improve operating efficiency through biomechanical mechanisms. However, the driving part of the flying thorn crystal still has nonlinear characteristics such as hysteresis and creep that affect the positioning accuracy, and the consistency and yield of the mass transfer of Mini LED chips still cannot be further improved. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the existing technology that the mass transfer of Mini LED chips still has positioning errors, and to provide a transfer system based on a bionic compliant mechanism and a flying thorn crystal compliant control method, which can effectively eliminate the hysteresis effect and creep problems, improve the positioning accuracy of the mass transfer of Mini LED chips, and improve work efficiency.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A transfer system based on a bionic compliant mechanism is provided, comprising a base and a two-dimensional moving device, a first X-direction moving device, and a first Y-direction moving device installed on the base, wherein the moving end of the two-dimensional moving device is used to install a MiniLED wafer, the moving end of the first X-direction moving device is provided with a bearing structure, and the moving end of the first Y-direction moving device is provided with a two-dimensional compliant flying thorn crystal device; wherein the two-dimensional compliant flying thorn crystal device comprises a bionic compliant mechanism, a thorn crystal mechanism connected to the bionic compliant mechanism, and a flight drive mechanism driven and connected to the bionic compliant mechanism, the bionic compliant mechanism has Y-direction and Z-direction degrees of freedom of movement, a flight displacement sensor is provided on the bionic compliant mechanism, and a force sensor is provided on the thorn crystal mechanism; and further comprising a control device which is communicatively connected to the two-dimensional moving device, the first X-direction moving device, the first Y-direction moving device, the thorn crystal mechanism, the flight drive mechanism, the flight displacement sensor, and the force sensor.

[0006] The present invention provides a transfer system based on a bionic compliant mechanism, wherein a first X-direction moving device is used to drive a bearing structure to reciprocate along the X-direction, a first Y-direction moving device is used to drive a two-dimensional compliant flying thorn crystal device to reciprocate along the Y-direction, and a two-dimensional moving device is used to drive a Mini LED wafer to reciprocate along the X-direction and the Y-direction; wherein the Z-direction movement freedom of the bionic compliant mechanism is used to transfer the Mini LED wafer to the bearing structure through the thorn crystal mechanism, and can monitor the contact force between the Mini LED wafer and the thorn crystal mechanism in real time through a force sensor, and the force sensor is used to maintain the contact force within a preset threshold range; the Y-direction movement freedom of the bionic compliant mechanism is used to compensate for the displacement difference of the Y-direction movement, and can monitor the Y-direction movement displacement of the bionic compliant mechanism in real time through a flying displacement sensor, so that the thorn crystal mechanism and the bearing structure remain relatively still, thereby realizing the alignment of the Mini LED wafer.

[0007] Furthermore, the flight drive mechanism includes piezoelectric ceramics and a bridge amplifier mechanism, the input end of the bridge amplifier mechanism is connected to the piezoelectric ceramics, and the output end of the bridge amplifier mechanism is connected to the bionic compliance mechanism; the piezoelectric ceramics are communicatively connected to the control device through a piezoelectric driver.

[0008] Furthermore, the first Y-axis moving device includes a gantry, to which is connected a first Y-axis guide rail, a first Y-axis linear motor, and a first Y-axis displacement sensor; a first slide plate is slidably connected to the first Y-axis guide rail, a driving end of the first Y-axis linear motor is connected to the first slide plate, and a 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] Further, the two-dimensional moving device includes a second Y-direction moving device and a second X-direction moving device, and the second Y-direction moving device is connected to the base through the second X-direction moving device; wherein the moving end of the second Y-direction moving device is used to mount the Mini LED wafer; the second X-direction moving device includes a first mounting seat located on both sides of the first X-direction moving device, the first mounting seat is connected to the base, and a second X-direction linear motor and a second X-direction displacement sensor are installed on the first mounting seat, the driving end of the second X-direction linear motor is connected to the fixed end of the second Y-direction moving device, and the second X-direction linear motor, the second X-direction displacement sensor, and the second Y-direction moving device are all communicatively connected to the control device.

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

[0011] The present invention also provides a flying thorn crystal compliance control method of a transfer system based on a bionic compliant mechanism, when the two-dimensional compliant flying thorn crystal device transfers the Mini LED wafer to the supporting structure:

[0012] The control device adopts open-loop feedforward control and contact force semi-closed-loop servo compliance control to control the Z-direction movement of the bionic compliance mechanism: the force sensor monitors the contact force between the Mini LED wafer and the thorn crystal mechanism in real time, and when the contact force between the two is greater than a preset threshold range, the Z-direction movement speed of the bionic compliance mechanism is reduced until the contact force between the Mini LED wafer and the thorn crystal mechanism is restored to within the preset threshold range;

[0013] The control device adopts double closed-loop high-bandwidth control to control the Y-direction movement of the bionic compliant mechanism: the Y-direction movement speed of the first Y-direction moving device is set to V1, the Y-direction movement speed of the two-dimensional moving device is set to V2, and the Y-direction movement speed of the bionic compliant mechanism is set to V3; the flight displacement sensor monitors the Y-direction movement displacement of the bionic compliant mechanism in real time, and makes the Y-direction movement speed satisfy: V1+V3=V2.

[0014] The present invention also provides a flying thorn crystal compliant control method for a transfer system based on a bionic compliant mechanism. In the Z-direction movement of the bionic compliant mechanism, the problem of poor thorn crystal positioning accuracy caused by hysteresis nonlinearity can be solved through open-loop feedforward control, and the consistency of mass transfer of Mini LED wafers can be improved by real-time monitoring of the contact force between the Mini LED wafer and the thorn crystal mechanism. In the Z-direction movement of the bionic compliant mechanism, dual closed-loop high-bandwidth control can be used to eliminate the steady-state error of the transfer system and improve the alignment accuracy of the thorn crystal mechanism and the Mini LED wafer.

[0015] Furthermore, the dual closed-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 closed-loop high-bandwidth control is:

[0016]

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

[0018]

[0019] The mathematical model of the integral control is:

[0020]

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

[0022] Furthermore, the mathematical model of the positive position feedback control is:

[0023]

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

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

[0026]

[0027] Where k represents the low-frequency gain coefficient, ω n represents the first-order natural frequency of the bionic compliant mechanism, s represents the complex variable in Laplace transform, and ξ represents the damping ratio of the bionic 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, and 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 present invention has the following beneficial effects:

[0030] The present invention relates to a transfer system based on a bionic compliant mechanism and a flying thorn crystal compliant control method. The Z-direction movement freedom of the bionic compliant mechanism of the transfer system is used to transfer the Mini LED wafer to the supporting structure through the thorn crystal mechanism, and the Y-direction movement freedom of the bionic compliant mechanism is used to compensate for the displacement difference of the Y-direction movement, so that the thorn crystal mechanism and the supporting structure remain relatively still, thereby realizing the alignment of the Mini LED wafer. In the Z-direction movement of the bionic compliant mechanism, the problem of poor thorn crystal positioning accuracy caused by hysteresis nonlinearity can be solved through open-loop feedforward control, and the consistency of mass transfer of Mini LED wafers can be improved by real-time monitoring of the contact force between the Mini LED wafer and the thorn crystal mechanism. In the Z-direction movement of the bionic compliant mechanism, the steady-state error of the transfer system can be eliminated through dual closed-loop high-bandwidth control, thereby improving the alignment accuracy of the thorn crystal mechanism and the Mini LED wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural schematic diagram of the transfer system based on the bionic compliant mechanism of the present invention;

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

[0033] Figure 3 It is a structural schematic diagram of the first X-direction moving device, the first Y-direction moving device, and the bearing structure of the present invention;

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

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

[0036] Figure 6 It is the Z-direction motion control loop structure of the bionic compliant mechanism of the present invention;

[0037] Figure 7 It is the Y-direction motion control loop structure of the bionic compliant mechanism of the present invention;

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

[0039] In the attached drawings: 100, base; 200, two-dimensional moving device; 210, second Y-direction moving device; 211, second mounting seat; 212, second Y-direction guide rail; 213, second Y-direction linear motor; 214, second Y-direction displacement sensor; 215, second slide plate; 216, second baffle plate; 220, first mounting seat; 230, second X-direction linear motor; 240, second X-direction displacement sensor; 300, first X-direction moving device; 310, first X-direction linear motor; 320, first X-direction displacement sensor; 400, first Y-direction moving device; 410, gantry seat; 420, first Y-direction guide rail; 430, first Y-direction linear motor; 440, first Y-direction displacement sensor; 450, first slide plate; 460, first baffle plate; 500, Mini LED wafer; 600, bearing structure; 610, carrier; 620, carrier platform; 700, two-dimensional compliant flying thorn crystal device; 710, bionic compliant mechanism; 720, thorn crystal mechanism; 721, ejector pin; 722, syringe; 730, flying drive mechanism; 731, piezoelectric ceramics; 732, bridge amplifier mechanism; 733, piezoelectric driver; 740, flying displacement sensor; 750, force sensor; 810, host computer; 820, industrial computer; 830, digital-to-analog conversion circuit board; 840, analog-to-digital conversion circuit board. DETAILED DESCRIPTION

[0040] The present invention is further described below in conjunction with specific implementation methods. The accompanying drawings are only used for exemplary descriptions and are only schematic diagrams, not actual drawings, and cannot be understood as limiting this patent; in order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the accompanying drawings may be omitted.

[0041] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the drawings, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limitations on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0042] Embodiment 1

[0043] like Figures 1 to 5The figure shows an embodiment of a transfer system based on a bionic compliant mechanism of the present invention, comprising a base 100 and a two-dimensional moving device 200, a first X-direction moving device 300, and a first Y-direction moving device 400 installed on the base 100. The moving end of the two-dimensional moving device 200 is used to install Mini LED wafer 500, the moving end of the first X-axis moving device 300 is provided with a bearing structure 600, and the moving end of the first Y-axis moving device 400 is provided with a two-dimensional flexible flying thorn crystal device 700; wherein, the two-dimensional flexible flying thorn crystal device 700 includes a bionic flexible mechanism 710, a thorn crystal mechanism 720 connected to the bionic flexible mechanism 710, and a flight drive mechanism 730 driven and connected to the bionic flexible mechanism 710, the bionic flexible mechanism 710 has the freedom of movement in the Y and Z directions, the bionic flexible mechanism 710 is provided with a flight displacement sensor 740, and the thorn crystal mechanism 720 is provided with a force sensor 750; and also includes a control device which 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 thorn crystal mechanism 720, the flight drive mechanism 730, the flight displacement sensor 740, and the force sensor 750.

[0044] The first X-direction moving device 300 is used to drive the supporting structure 600 to reciprocate along the X-direction, the first Y-direction moving device 400 is used to drive the two-dimensional flexible flying thorn crystal device 700 to reciprocate along the Y-direction, and the two-dimensional moving device 200 is used to drive the Mini LED wafer 500 to reciprocate along the X-direction and the Y-direction; wherein, the Z-direction movement freedom of the bionic flexible mechanism 710 is used to transfer the Mini LED wafer 500 to the supporting structure 600 through the thorn crystal mechanism 720, and can monitor the contact force between the Mini LED wafer 500 and the thorn crystal mechanism 720 in real time through the force sensor 750, so that the contact force is maintained within a preset threshold range; the Y-direction movement freedom of the bionic flexible mechanism 710 is used to compensate for the displacement difference of the Y-direction movement, and can monitor the Y-direction movement displacement of the bionic flexible mechanism 710 in real time through the flying displacement sensor 740, so that the thorn crystal mechanism 720 and the supporting structure 600 remain relatively still, thereby realizing 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 amplifier mechanism 732. The input end of the bridge amplifier mechanism 732 is connected to the piezoelectric ceramic 731, and the output end of the bridge amplifier mechanism 732 is connected to the bionic compliance mechanism 710; the piezoelectric ceramic 731 is connected to the control device through a piezoelectric driver 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 thorn crystal mechanism 720 includes a pin 721 and a syringe 722. The pin 721 is connected to the bionic compliance mechanism 710 through the syringe 722.

[0046] It should be noted that the bionic compliant mechanism 710 is set according to the biomechanical characteristics of the original pigeon. The original pigeon has good air resistance characteristics during flight, which can reduce energy consumption. Compared with other bird creatures, the original pigeon has a larger amplitude during wing flapping, so this characteristic can be used for chip transfer of the large-stroke Mini LED wafer 500; wherein, the bionic compliant mechanism 710 includes a thorn crystal connector and an imitation original pigeon wing structure, and the imitation original pigeon wing structure includes an imitation carpal metacarpal beam, an imitation forearm beam, an imitation humerus beam, and an imitation scapula beam arranged in sequence, and adjacent bone beams are connected by flexible hinges, and the imitation carpal metacarpal beam is connected to the thorn crystal connector through a flexible hinge, and the thorn crystal connector is connected to the syringe 722 of the thorn crystal mechanism 720. And, the bridge-type amplification mechanism 732 is a prior art and will not be described in detail here. The two-dimensional compliant flying thorn crystal device 700 has high-precision displacement generation performance. Through the combination of the bionic 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-direction moving device 400 includes a gantry seat 410, to which a first Y-direction guide rail 420, a first Y-direction linear motor 430, and a first Y-direction displacement sensor 440 are connected, and a first slide plate 450 is slidably connected to the first Y-direction guide rail 420, a driving end of the first Y-direction linear motor 430 is connected to the first slide plate 450, and a bridge-type amplifying mechanism 732 is connected to the first slide plate 450; the first Y-direction linear motor 430 and the first Y-direction displacement sensor 440 are both connected to the control device for communication. In this embodiment, first baffles 460 are also provided at both ends of the first Y-direction guide rail 420, and the first baffles 460 are connected to the gantry seat 410, and the setting of the first baffles 460 can prevent the first slide plate 450 from detaching from the first Y-direction 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 installed on the base 100, and the first X-axis linear motor 310 and the first X-axis displacement sensor 320 are both located below the gantry 410. The bearing structure 600 includes a carrier platform 620 and a carrier 610 installed on the carrier platform 620, the carrier platform 620 is connected to the driving end of the first X-axis linear motor 310, and the carrier 610 is located below the thorn crystal 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, and the second Y-axis moving device 210 is connected to the base 100 through the second X-axis moving device; wherein, the moving end of the second Y-axis moving device 210 is used to install the Mini LED wafer 500; the second X-axis moving device includes a first mounting seat 220 located on both sides of the first X-axis moving device 300, the first mounting seat 220 is connected to the base 100, and a second X-axis linear motor 230 and a second X-axis displacement sensor 240 are installed on the first mounting seat 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, and the second X-axis linear motor 230, the second X-axis displacement sensor 240, and the second Y-axis moving device 210 are all connected to the control device for communication.

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

[0052] like Figure 5 As shown, the control device includes a host computer 810, an industrial computer 820 communicatively connected to the host computer 810, and also includes a digital-to-analog conversion circuit board 830 and an analog-to-digital conversion circuit board 840 communicatively connected to the industrial 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 computer 820, the piezoelectric driver 733 is communicatively connected to the digital-to-analog conversion circuit board 830, and the flight displacement sensor 740 and the force sensor 750 are all communicatively connected to the analog-to-digital conversion circuit board 840.

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

[0054] The first X-direction moving device 300 can drive the supporting structure 600 to move to the bottom of the Mini LED wafer 500, the two-dimensional moving device 200 can drive the Mini LED wafer 500 to move in the X-direction and the Y-direction, the first Y-direction moving device 400 and the bionic compliant mechanism 710 can drive the thorn crystal mechanism 720 to move in the Y-direction, and the bionic compliant mechanism 710 can also drive the thorn crystal mechanism 720 to move in the Z-direction and perform thorn crystal. During the movement of the thorn crystal mechanism 720, the force sensor 750 can monitor the contact force between the Mini LED wafer 500 and the thorn crystal 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-direction movement displacement of the bionic compliant mechanism 710 in real time, and then keep the thorn crystal mechanism 720 and the supporting structure 600 relatively still through the control of the control device, so as to realize the alignment of the Mini LED wafer 500.

[0055] Embodiment 2

[0056] This embodiment is the first embodiment of a flying thorn crystal compliance control method of a transfer system based on a bionic compliance mechanism of the present invention, and the method includes: when the two-dimensional flexible flying thorn crystal device 700 transfers the Mini LED wafer 500 to the supporting structure 600:

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

[0058] The control device adopts double closed-loop high-bandwidth control to control the Y-direction movement of the bionic compliant mechanism 710: the Y-direction movement speed of the first Y-direction moving device 400 is set to V1, the Y-direction movement speed of the two-dimensional moving device 200 is set to V2, and the Y-direction movement speed of the bionic compliant mechanism 710 is set to V3; the flying displacement sensor 740 monitors the Y-direction movement displacement of the bionic compliant mechanism 710 in real time, and makes the Y-direction movement speed satisfy: V1+V3=V2.

[0059] In the Z-direction movement of the bionic flexible mechanism 710, the problem of poor positioning accuracy of the spike crystal caused by hysteresis nonlinearity can be solved through open-loop feedforward control, and the consistency of mass transfer of the Mini LED wafer 500 can be improved by real-time monitoring of the contact force between the Mini LED wafer 500 and the spike crystal mechanism 720. In the Z-direction movement of the bionic flexible mechanism 710, dual closed-loop high-bandwidth control can be used to eliminate the steady-state error of the transfer system and improve the alignment accuracy of the spike crystal mechanism 720 and the Mini LED wafer 500.

[0060] Embodiment 3

[0061] This embodiment is the second embodiment of the present invention, a method for controlling the compliance of a flying spike crystal in a transfer system based on a bionic compliance mechanism. This embodiment is similar to the second embodiment. Figures 6 to 8 As shown, the difference is:

[0062] The industrial computer 820 outputs an analog voltage to control the output voltage of the piezoelectric driver 733 through the digital-to-analog conversion circuit board 830 according to the control algorithm requirements of the host computer 810. The piezoelectric driver 733 amplifies the control voltage and outputs the voltage 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 amplifier mechanism 732 and output to the bionic compliance mechanism 710. The bionic compliance mechanism 710 drives the thorn crystal mechanism 720 to move. During the movement of the thorn crystal mechanism 720:

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

[0064] The host computer 810 controls the Y-direction movement of the bionic compliant mechanism 710 based on dual closed-loop high-bandwidth control: the Y-direction movement speed of the first Y-direction moving device 400 is set to V1, the Y-direction movement speed of the second Y-direction moving device 210 is set to V2, and the Y-direction movement speed of the bionic compliant mechanism 710 is set to V3; the capacitive displacement sensor monitors the Y-direction movement displacement of the bionic compliant mechanism 710 in real time, and makes the Y-direction movement speed satisfy: V1+V3=V2.

[0065] Among them, Figures 6 to 8 As shown, the dual closed-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 closed-loop high-bandwidth control is:

[0066]

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

[0068]

[0069] The mathematical model of integral control is:

[0070]

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

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

[0073]

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

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

[0076]

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

[0078] Specifically, due to the "small damping" and "low natural frequency" characteristics of the bionic compliant mechanism 710, when closed-loop control is adopted, the bandwidth frequency of the transfer system will be less than 10% of the first-order natural frequency. In the present invention, the inner-loop control can be used to improve the equivalent damping and equivalent natural frequency of the transfer system, that is, using the control algorithm of positive position feedback, the bionic compliant mechanism 710 can be regarded as a second-order underdamped system, and its transfer function can be expressed as It should be noted that the transfer function of the bionic compliant mechanism 710 can be obtained by system identification. The mathematical model of positive position feedback control can be expressed as The design parameter K p ,ω p , η p It can be obtained by optimizing the algorithm. Positive position feedback control can ensure control stability and sufficient phase margin to maximize the closed-loop bandwidth of the transfer system. The transfer function of the inner loop control can be expressed as Positive position feedback control can effectively improve the closed-loop bandwidth frequency of the transfer system, thereby increasing the alignment speed in the solid crystal process. In order to solve the problem of alignment accuracy in the Y direction of the bionic compliant mechanism 710, the present invention also uses outer loop control, that is, adding a negative feedback control on the basis of the inner loop control, to eliminate the steady-state error of the transfer system and improve the positioning accuracy. To achieve the above functions, the present invention adds integral control to the outer loop control to improve the type of the closed-loop system and reduce the steady-state error. Therefore, the open-loop transfer function of the dual closed-loop high-bandwidth control is: The transfer function of the dual closed-loop high-bandwidth control is:

[0079]

[0080] Specifically, the open-loop feedforward function of the open-loop feedforward control is obtained by obtaining the hysteresis loop of the piezoelectric ceramic 731 through an open-loop test experiment, and fitting the hysteresis loop according to the mathematical model of the Prandtl-Ishlinskii hysteresis operator to obtain the hysteresis mathematical model of the piezoelectric ceramic 731, and then solving the inverse model of the hysteresis mathematical model to obtain the open-loop feedforward function.

[0081] The present invention provides a crystal piercing compliance control method for a transfer system based on a bionic compliance mechanism, which has the advantages of high bandwidth, compliance, and flight. When the contact force between the ejector pin 721 and the chip of the Mini LED wafer 500 is too large during the crystal piercing process, the piezoelectric drive voltage value is reduced to prevent the chip of the Mini LED wafer 500 from affecting the consistency of transfer due to excessive contact force. In view of the low bandwidth of the bionic compliance mechanism 710 and the hysteresis effect of the piezoelectric ceramic 731, high bandwidth control and compliance control can be combined to effectively eliminate the hysteresis effect of the piezoelectric ceramic 731 and improve the closed-loop control bandwidth.

[0082] In the specific contents of the above-mentioned specific implementation methods, the various technical features can be combined in any non-contradictory manner. In order to make the description concise, not all possible combinations of the above-mentioned technical features are described. However, as long as there is no contradiction in the combination of these technical features, they 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 embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A transfer system based on a bionic compliant mechanism, characterized in that: The invention comprises a base (100) and a two-dimensional moving device (200), a first X-direction moving device (300), and a first Y-direction moving device (400) installed on the base (100); the moving end of the two-dimensional moving device (200) is used to install a Mini LED wafer (500); the moving end of the first X-direction moving device (300) is provided with a bearing structure (600); the moving end of the first Y-direction moving device (400) is provided with a two-dimensional flexible flying thorn crystal device (700); wherein the two-dimensional flexible flying thorn crystal device (700) comprises a bionic flexible mechanism (710), a thorn crystal mechanism (720) connected to the bionic flexible mechanism (710), and a flight driving mechanism (730) driven and connected to the bionic flexible mechanism (710); the bionic flexible mechanism (710) is provided with a bearing structure (600); and the two-dimensional flexible flying thorn crystal device (700) is provided with a two-dimensional flexible flying thorn crystal device (700). The compliant mechanism (710) has the freedom of movement in the Y direction and the Z direction. The bionic compliant mechanism (710) is provided with a flight displacement sensor (740), and the thorn crystal mechanism (720) is provided with a force sensor (750). The bionic compliant mechanism (710) also includes a control device that is communicatively connected to the two-dimensional moving device (200), the first X-direction moving device (300), the first Y-direction moving device (400), the thorn crystal mechanism (720), the flight drive mechanism (730), the flight displacement sensor (740), and the force sensor (750).

2. The transfer system based on the bionic compliant mechanism according to claim 1, characterized in that: The flight drive mechanism (730) comprises a piezoelectric ceramic (731) and a bridge amplifier mechanism (732); the input end of the bridge amplifier mechanism (732) is connected to the piezoelectric ceramic (731), and the output end of the bridge amplifier mechanism (732) is connected to the bionic compliance mechanism (710); the piezoelectric ceramic (731) is communicatively connected to the control device via a piezoelectric driver (733).

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

4. The transfer system based on bionic compliant mechanism according to claim 1, characterized in that: The two-dimensional moving device (200) comprises a second Y-direction moving device (210) and a second X-direction moving device, wherein the second Y-direction moving device (210) is connected to the base (100) via the second X-direction moving device; wherein the moving end of the second Y-direction moving device (210) is used to mount the Mini LED wafer (500); the second X-direction moving device comprises a first mounting seat (220) located on both sides of the first X-direction moving device (300), wherein the first mounting seat (220) is connected to the base (100), and a second X-direction linear motor (230) and a second X-direction displacement sensor (240) are mounted on the first mounting seat (220), wherein the driving end of the second X-direction linear motor (230) is connected to the fixed end of the second Y-direction moving device (210), and the second X-direction linear motor (230), the second X-direction displacement sensor (240) and the second Y-direction moving device (210) are all connected to the control device for communication.

5. The transfer system based on a bionic compliant mechanism according to any one of claims 1 to 4, characterized in that: The control device comprises a host computer (810), an industrial computer (820) communicatively connected to the host computer (810), and also comprises a digital-to-analog conversion circuit board (830) and an analog-to-digital conversion circuit board (840) communicatively connected to the industrial computer (820); the two-dimensional moving device (200), the first X-direction moving device (300), and the first Y-direction moving device (400) are all communicatively connected to the industrial computer (820), the flight drive mechanism (730) is communicatively connected to the digital-to-analog conversion circuit board (830), and the flight displacement sensor (740) and the force sensor (750) are all communicatively connected to the analog-to-digital conversion circuit board (840).

6. A flying spike crystal compliance control method for a transfer system based on a bionic compliance mechanism according to any one of claims 1 to 5, characterized in that: When the two-dimensional flexible flying thorn crystal device (700) transfers the Mini LED wafer (500) to the supporting structure (600): The control device adopts open-loop feedforward control and contact force semi-closed-loop servo compliance control to control the Z-direction movement of the bionic compliance mechanism (710): the force sensor (750) monitors the contact force between the Mini LED wafer (500) and the thorn crystal mechanism (720) in real time, and when the contact force between the two is greater than a preset threshold range, the Z-direction movement speed of the bionic compliance mechanism (710) is reduced until the contact force between the Mini LED wafer (500) and the thorn crystal mechanism (720) is restored to within the preset threshold range; The control device adopts double closed-loop high-bandwidth control to control the Y-direction movement of the bionic compliant mechanism (710): assuming that the Y-direction movement speed of the first Y-direction moving device (400) is V1, the Y-direction movement speed of the two-dimensional moving device (200) is V2, and the Y-direction movement speed of the bionic compliant mechanism (710) is V3; the flight displacement sensor (740) monitors the Y-direction movement displacement of the bionic compliant mechanism (710) in real time, and makes the Y-direction movement speed satisfy: V1+V3=V2.

7. The flying thorn crystal compliance control method according to claim 6 is characterized in that: The dual closed-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 closed-loop high-bandwidth control is: The transfer function of the inner loop control is: The mathematical model of the integral control is: Wherein, G(s) represents the transfer function of the bionic compliant mechanism (710), C p (s) represents the mathematical model of the positive position feedback control, K i represents the integral coefficient, and s represents the complex variable in the Laplace transform.

8. The flying thorn crystal compliance control method according to claim 7 is characterized in that: The mathematical model of the positive position feedback control is: In the formula, K p represents the gain of positive position feedback control, ω p represents the natural frequency of positive position feedback control, s represents the complex variable in Laplace transform, η p Indicates the damping ratio of the positive position feedback control.

9. The flying thorn crystal compliance control method according to claim 7 is characterized in that: The transfer function of the bionic compliant mechanism (710) is: Where k represents the low-frequency gain coefficient, ω n represents the first-order natural frequency of the bionic compliant mechanism (710), s represents a complex variable in Laplace transform, and ξ represents the damping ratio of the bionic compliant mechanism (710).

10. The flying thorn crystal compliance control method according to claim 6, characterized in that: The open-loop feedforward function of the open-loop feedforward control is obtained by: obtaining the hysteresis loop of the piezoelectric ceramic (731) of the flight drive mechanism (730) through an open-loop test experiment, and fitting the hysteresis loop according to the mathematical model of the hysteresis operator to obtain the hysteresis mathematical model of the piezoelectric ceramic (731), and then solving the inverse model of the hysteresis mathematical model to obtain the open-loop feedforward function.

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