CN114869586A

CN114869586A - High-precision retina injection device

Info

Publication number: CN114869586A
Application number: CN202210539531.2A
Authority: CN
Inventors: 李云耀; 蒋天亮; 唐宁; 樊金宇; 邢利娜; 史国华
Original assignee: Suzhou Institute of Biomedical Engineering and Technology of CAS
Current assignee: Suzhou Institute of Biomedical Engineering and Technology of CAS
Priority date: 2022-05-18
Filing date: 2022-05-18
Publication date: 2022-08-09

Abstract

The invention discloses a high-precision retina injection device, which comprises a trocar for injection, a metal tube and a stepping motor; the injection trocar and the end part of the metal tube are connected with the stepping motor, and the metal tube is driven by the stepping motor to do linear motion along the axial direction. The control module comprises a core control unit, a serial port submodule, a motor submodule and an operation submodule; the control module is controlled by programs, including a mode selection subprogram, a step setting subprogram, a speed control subprogram, a position display subprogram, a direction control subprogram and a return-to-initial position subprogram. The invention adopts a high-precision stepping motor, drives the injection needle in a screw rod transmission mode, and eliminates the influence of hand tremor in a non-handheld injection mode. The split design is adopted, so that the shell of the device is more compact, and the whole volume is greatly reduced by selecting small parts; the needle tube is connected with the metal tube only through threads, so that the needle tube is easy to replace and the cost can be effectively reduced.

Description

High-precision retina injection device

Technical Field

The invention belongs to the technical field of medical robots, and particularly relates to a high-precision retina injection device.

Background

The retina is the most complex component of the human eye, and age-related macular degeneration or AMD is the most common retinal degenerative disease that causes blindness and incurability in patients. The most advanced treatment method at present is the injection of stem cell-derived retinal pigment cells (RPE cells) into the retina, forming a new RPE layer. The technology has been proven to be safe for human body on animal model at present, and some clinical tests aiming at human body have been successful at early stage. However, manually operated fundus surgery has extremely high accuracy requirements: ophthalmic surgery is performed in scleral incisions less than 1mm in diameter, in retinal surgery, the target retinal tissue is as thin as 25 μm, and the amplitude of the surgeon's physiological hand tremor is around 182 μm, which cannot achieve the precision required by the surgery, so the injection of the intraretinal stem cells is difficult to perform in a conventional manual manner.

There have been some related studies in recent years to improve injection accuracy using a specially made injection device. A hand-held injection device is designed according to the article (Gonenc, B, et al, Towards Robot-Assisted vehicle administration: A Motorized Force-Sensing micro-Integrated with a hand-held Micromanipulator [ J ]. Sensors,2017,17(10):2195.) and aims at Retinal Vein intubation, a needle tube with a micro-Force sensor is used, the moment of Vein puncture can be accurately detected, and meanwhile, a motor at the tail end of the device is controlled based on a compensation algorithm to eliminate physiological tremor of hands of doctors. This device increases the time (average 8.47s) for the user to hold the needle within a minimum tolerance (100 μm), but needle tolerances of up to 500 μm are still possible during prolonged use. And because the manual mode is still adopted for injection, the feeding amount of the injection is difficult to control, and the injection is difficult to apply to the retinal injection operation. The article (Xiao, J J, et al, design and Research of a spherical air System for reliable spatial Bypass Surgery [ J ]. Journal of medical Devices-Transactions of ASME,2015,8(4):044501.) designed a Retinal injection device for surgical robots, which has better positioning accuracy for Retinal vein intubation than manual control, but the error can still reach +/-0.1 mm, possibly causing damage to the ocular fundus microstructure. An injection device for Retinal Vein intubation is also designed in the article (Gijbels, A, et al, development and Experimental variation of a Force Sensing Needle for Retinal Vein intubation [ J ]. IEEE International Conference on Robotics and administration ICRA,2015:2270-2276.) and the device is axially fed by a motor without errors caused by physiological tremor, can be stably fed at a speed of 0.4mm/s and has higher precision. However, the drive motor of this device is bulky and not integrated with the injection needle, resulting in a less compact and bulky device as a whole, which can cause interference during the actual injection.

In summary, the major drawbacks of the prior art ophthalmic surgical injection devices are: insufficient positioning precision, incapability of accurately controlling the feeding amount, overlarge volume, complex design and the like. The injection devices are developed aiming at retinal vein intubation, cannot be directly applied to retinal stem cell injection, and special injection devices need to be developed aiming at retinal stem cell injection.

Disclosure of Invention

The invention aims to provide a special high-precision injection device for retinal stem cell injection, which solves the problems that the prior ophthalmic injection instrument has insufficient positioning precision, can not accurately control the feeding amount, has overlarge volume and complex design.

In order to realize the purpose of the invention, the invention discloses a high-precision retina injection device, which comprises a trocar for injection, a metal tube and a stepping motor; the injection trocar and the end part of the metal tube are connected with the stepping motor, and the metal tube is driven by the stepping motor to do linear motion along the axial direction.

Further, the trocar for injection comprises a microneedle and a needle tube; the micro-needle is a metal needle tube, is adhered to the tail end of the needle tube by using an adhesive, and is connected to the tail end of the metal tube.

Furthermore, the device is integrally arranged on the shell seat; the needle tube protection cover and the stepping motor base are arranged on the shell base, the needle tube protection cover is arranged on the outer side of the metal tube, and the stepping motor base is arranged at the bottom of the stepping motor.

Furthermore, a first straight line bearing seat is arranged on one side, close to the trocar for injection, of the needle tube protective cover, the bottom of the first straight line bearing seat is arranged on the outer shell seat, a groove is formed in the top of the first straight line bearing seat, and the first straight line bearing is arranged in the groove; a second linear bearing seat is arranged above the stepping motor seat, a through hole is formed in the second linear bearing seat, and a second linear bearing is arranged in the through hole.

Further, an output shaft of the stepping motor is connected with the ball screw; the tail end of the ball screw is radially positioned through a radial bearing embedded into the first linear bearing seat in an interference fit mode, and axially positioned through an end cover fixed on the first linear bearing seat through a bolt; the outer side of the ball screw is sleeved with a terminal, an output shaft of the stepping motor rotates to drive the ball screw to rotate, and the terminal is driven to do linear motion along the ball screw through screw transmission so as to be converted into linear motion of the metal pipe; one side of the terminal is connected to the bottom of the connecting piece, the top of the connecting piece is connected with the metal pipe, and the terminal moves to drive the connecting piece to move so as to drive the metal pipe to move linearly; the two ends of the metal pipe are radially positioned by a first linear bearing and a second linear bearing; the whole device is provided with motive power by the stepping motor, and the rotation of an output shaft of the stepping motor is converted into the linear motion of the metal pipe.

Furthermore, a first connecting bearing seat and a second connecting bearing seat are arranged on the shell seat; the first connecting bearing seat is positioned below the trocar for injection, a through hole is formed in the first connecting bearing seat, and a first connecting bearing group is arranged in the through hole; the second connecting bearing seat is arranged below the needle tube protection cover, a through hole is formed in the second connecting bearing seat, and a second connecting bearing group is arranged in the through hole; the first connecting bearing group and the second connecting bearing group are used for connecting the surgical robot.

Further, the stepping motor is connected with the control module; the control module comprises a core control unit, a serial port submodule, a motor submodule and an operation submodule;

the core control unit outputs PWM waves by using timer TIM of the singlechip; the generation of PWM waves is manually controlled by a controller of the control submodule, and the controller comprises a key, a handle or a hand wheel;

the serial port submodule is used for realizing serial port communication between the PC terminal and the singlechip, and the singlechip returns the position information of the device and displays the position information on the PC;

the motor submodule comprises a stepping motor and a driver, and the driver is used for receiving signals of the single chip microcomputer and then outputting pulses to control the stepping motor.

Further, the PC is connected with the single chip microcomputer through a USB port and communicates by using a UART serial port; a controller in the control sub-module is connected with the single chip microcomputer through a GPIO port, and the GPIO port serves as an input end and receives a control signal; a PUL port on a driver in the motor submodule is a pulse port and is responsible for controlling the pulse of a driving motor, an ENA port is an enabling port and is responsible for controlling the on-off of the motor, and a DIR port is a direction port and is responsible for controlling the rotation direction of the motor; the connecting line between the driver and the single chip microcomputer adopts a differential connection method, a port PUL-, a port ENA-, a port DIR-and a GND port of the single chip microcomputer are connected with the ground, the port PUL +, the port ENA + and the port DIR + are respectively connected with three GPIO ports of the single chip microcomputer, the three GPIO ports are used as output ends, and the GPIO ports connected with the port PUL + are multiplexed into a timer and used for outputting PWM waves; the stepping motor and the driver adopt a four-wire connection method, and the power supply end of the driver is connected with a direct current power supply.

Furthermore, the stepping motor is controlled in a pulse-direction mode, the level of a DIR port changes and controls the rotation direction, and a PUL port outputs pulse waves to control the rotating speed and the step number of the motor, wherein the pulse waves are independent of each other; the PWM output adopts the timer function of a singlechip and adopts an up-counting mode, a CCR register stores a target value, an ARR register stores a highest value, a timer counts according to the system frequency, an IO port outputs a high level when the value reaches the target value, the timer counts and clears the value until the value reaches the highest value, and the IO port becomes a low level; the period of the PWM wave is changed by changing the value of the ARR register, so that the rotating speed of the motor can be changed; by modifying the subdivision number of the controller, the feed rate of the injection tip can be accurate to microns per second.

Furthermore, the control module performs control through programs, including a mode selection subprogram, a step setting subprogram, a speed control subprogram, a position display subprogram, a direction control subprogram and a return-to-initial position subprogram; the mode selection subroutine is used for selecting a position control mode and a speed control mode; the step pitch setting subroutine is used for changing the single step pitch of the motor by changing the pulse number in the position control mode; the speed control subprogram is used for changing the speed of the motor by changing the pulse period in the speed control mode; the position display subprogram is used for converting the current position of the motor into the current position of the needle point and returning the current position of the needle point to the PC through the serial port; the direction control subroutine is used for changing the rotation direction of the motor by changing the level of the DIR + port; the return-to-initial position subroutine is used for recording the current position at any time when the motor works and returning to the initial position when a return-to-zero instruction is received.

Compared with the prior art, the invention has the remarkable improvements that: 1) the prior ophthalmic injection instrument has limited precision, and the hand-held device can not completely eliminate the influence of hand tremor and is difficult to meet the precision requirement of retinal surgery. The electric injection device generally does not aim at the retina injection operation, generally has low requirement on the feeding precision, and is difficult to be used for the retina injection operation. The invention adopts a high-precision stepping motor, drives the injection needle in a screw rod transmission mode, and eliminates the influence of hand tremor in a non-handheld injection mode. The repeated positioning precision can reach the micron level, the feeding speed can also reach the micron per second, and the precision requirement of retina injection is met. 2) The injection device for retinal vascular surgery or anterior segment surgery has been used for retinal intraocular injection because the needle tip is oversized and the length or feed rate is insufficient. Aiming at the retina injection operation, the invention uses a 0.1mm micro-needle and 32G and 23G needle tube combined trocar, which can meet the requirement of retina puncture, and meanwhile, the axial feed of the needle tube reaches 80mm, which can ensure the retina to reach. 3) The problem of excessive bulk common to current ophthalmic injection devices is particularly apparent in devices using motor control. Being too bulky can affect ergonomics and can crush the workspace or interfere with navigation equipment during surgery. In addition, most injection devices are still under investigation, using an integral housing, making their disassembly and assembly difficult and the needle cannula difficult to replace. The invention adopts a split design, so that the shell of the device is more compact, and the whole volume is greatly reduced by selecting small parts. Meanwhile, the needle tube is connected with the metal tube only through threads, so that the needle tube is easy to replace, and the cost can be effectively reduced.

To more clearly illustrate the functional characteristics and structural parameters of the present invention, the following description is given with reference to the accompanying drawings and the detailed description.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention. In the drawings:

FIG. 1 is a schematic view of the general assembly of the present invention;

FIG. 2 is a schematic view of the trocar for injection of the present invention;

FIG. 3 is a schematic view of the housing structure of the present invention;

FIG. 4 is a schematic diagram of an output structure of the stepping motor according to the present invention;

FIG. 5 is a schematic view of a connecting bearing set according to the present invention;

FIG. 6 is a drawing of the size of the lead screw of the stepping motor of the present invention;

FIG. 7 is a schematic diagram of a control module according to the present invention;

FIG. 8 is a wiring diagram of the control module of the present invention;

FIG. 9 is a timing diagram illustrating the control of the stepper motor according to the present invention;

the reference numbers in the figures are: the needle tube protection device comprises a trocar 1 for injection, a metal tube 2, a stepping motor 3, a microneedle 4, a needle tube 5, a shell seat 6, a needle tube protection cover 7, a stepping motor seat 8, a ball screw 9, a radial bearing 10, an end cover 11, a terminal 12, a connecting piece 13, a first linear bearing 14, a second linear bearing 15, a first linear bearing seat 16, a second linear bearing seat 17, a first connecting bearing seat 18, a second connecting bearing seat 19, a first connecting bearing group 20 and a second connecting bearing group 21.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments; all other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.

Examples

As shown in fig. 1, fig. 1 is a general assembly diagram of the present invention. The injection trocar 1 and the end part of the metal tube 2 are connected with the stepping motor 3, and the metal tube 2 is driven by the stepping motor 3 to do linear motion along the axial direction.

As shown in figure 2, figure 2 is a schematic view of the injection trocar of the present invention. The injection trocar 1 comprises a microneedle 4 and a needle tube 5; the microneedle 4 is a metal needle tube and is bonded to the tail end of the needle tube 5 by using an adhesive, and the needle tube 5 is connected to the tail end of the metal tube 2.

Specifically, in the present embodiment, the microneedle 1 is a metal needle tube with an outer diameter of 0.1mm, and the tip of the needle is a 15 ° notch. The needle tube 2 is a standard 32G (0.25 mm outer diameter) needle tube and is connected to the end of the metal tube 3 by a screw thread.

As shown in fig. 3 and 5, fig. 3 is a schematic structural diagram of the housing of the present invention, and fig. 5 is a schematic structural diagram of the connecting bearing set of the present invention. The device is integrally arranged on the shell seat 6; the outer shell base 6 is provided with a needle tube protection cover 7 and a stepping motor base 8, the needle tube protection cover 7 is arranged on the outer side of the metal tube 2, and the stepping motor base 8 is arranged at the bottom of the stepping motor 3. A first linear bearing seat 16 is arranged on one side, close to the trocar 1, of the needle tube protective cover 7, the bottom of the first linear bearing seat 16 is arranged on the shell seat 6, a groove is formed in the top of the first linear bearing seat 16, and a first linear bearing 14 is arranged in the groove; a second linear bearing seat 17 is arranged above the stepping motor seat 8, a through hole is arranged on the second linear bearing seat 17, and a second linear bearing 15 is arranged in the through hole.

The shell seat 6 is provided with a first connecting bearing seat 18 and a second connecting bearing seat 19; the first connecting bearing seat 18 is positioned below the trocar 1 for injection, a through hole is arranged in the first connecting bearing seat 18, and a first connecting bearing group 20 is arranged in the through hole; the second connecting bearing seat 19 is arranged below the needle tube protective cover 7, a through hole is formed in the second connecting bearing seat 19, and a second connecting bearing group 21 is arranged in the through hole; the first connecting bearing set 20 and the second connecting bearing set 21 are used for connecting the surgical robot.

Specifically, in this embodiment, the whole housing is designed to be detachable, so that the assembly difficulty is greatly reduced, and the housing is easier to disassemble and maintain in the later period. The needle cannula portion is not directly connected to the housing module and therefore can be replaced directly without disassembly of the housing.

As shown in fig. 4, fig. 4 is a schematic diagram of an output structure of the stepping motor of the present invention. An output shaft of the stepping motor 3 is connected with a ball screw 9; the end of the ball screw 9 is provided with radial positioning by a radial bearing 10 embedded in the first linear bearing seat 16 in an interference fit, and axial positioning by an end cover 11 bolted to the first linear bearing seat 16; a terminal 12 is sleeved on the outer side of the ball screw 9, an output shaft of the stepping motor 3 rotates to drive the ball screw 9 to rotate, and the terminal 12 is linearly moved along the ball screw 9 through screw transmission so as to be converted into linear movement of the metal pipe; one side of the terminal 12 is connected with the bottom of the connecting piece 13, the top of the connecting piece 13 is connected with the metal tube 2, and the terminal 12 moves to drive the connecting piece 13 to move, so that the metal tube 2 is driven to move linearly; the two ends of the metal pipe 2 are radially positioned by a first linear bearing 14 and a second linear bearing 15; in the whole device, the stepping motor 3 provides motive power to convert the rotation of the output shaft of the stepping motor 3 into the linear motion of the metal pipe 2.

Specifically, in the present embodiment, the ball screw diameter is 4.76mm, and the thread lead is 1.27 mm. The terminal 12 and the connecting member 13 are fixed by bolts.

As shown in fig. 6, fig. 6 is a size diagram of the screw rod of the stepping motor of the present invention. The stepping motor 3 is a special motor of an injection device, the model is 20E2805, the design is based on a 20-step motor of a standard specification, the leading-out end of the stepping motor is a ball screw with the diameter of 4.76mm, the length of the threaded part of the ball screw is 80mm, and the lead is 1.27 mm.

As shown in fig. 7, fig. 7 is a schematic diagram of a control module according to the present invention. The control module comprises a core control unit, a serial port submodule, a motor submodule and an operation submodule; the core control unit outputs PWM waves by using timer TIM of the singlechip; the generation of PWM waves is manually controlled by a controller of the control submodule, and the controller comprises a key, a handle or a hand wheel; the serial port submodule is used for realizing serial port communication between the PC terminal and the singlechip, and the singlechip returns the position information of the device and displays the position information on the PC; the motor submodule comprises a stepping motor 3 and a driver, and the driver is used for receiving the signal of the singlechip and then outputting a pulse to control the stepping motor 3.

Specifically, in this embodiment, the core control unit is an STM32F103 single chip microcomputer; the controller can select a key, a handle or a hand wheel and is controlled in a manual operation mode; the drive model is MAD 322R.

As shown in fig. 8, fig. 8 is a wiring diagram of the control module of the present invention. The PC is connected with the singlechip through a USB port and communicates by using a UART serial port; a controller in the control sub-module is connected with the single chip microcomputer through a GPIO port, and the GPIO port serves as an input end and receives a control signal; a PUL port on a driver in the motor submodule is a pulse port and is responsible for controlling the pulse of a driving motor, an ENA port is an enabling port and is responsible for controlling the on-off of the motor, and a DIR port is a direction port and is responsible for controlling the rotation direction of the motor; the connecting line between the driver and the single chip microcomputer adopts a differential connection method, a port PUL-, a port ENA-, a port DIR-and a GND port of the single chip microcomputer are connected with the ground, the port PUL +, the port ENA + and the port DIR + are respectively connected with three GPIO ports of the single chip microcomputer, the three GPIO ports are used as output ends, and the GPIO ports connected with the port PUL + are multiplexed into a timer and used for outputting PWM waves; the stepping motor 3 and the driver adopt a four-wire connection method, and the power supply end of the driver is connected with a direct current power supply.

As shown in fig. 9, fig. 9 is a timing chart of the stepping motor control according to the present invention. The stepping motor (3) is controlled in a pulse-direction mode, the level of a DIR port is changed to control the rotation direction, and a PUL port outputs pulse waves to control the rotation speed and the step number of the motor, wherein the pulse waves are independent of each other; the PWM output adopts the timer function of a singlechip and adopts an up-counting mode, a CCR register stores a target value, an ARR register stores a highest value, a timer counts according to the system frequency, an IO port outputs a high level when the value reaches the target value, the timer counts and clears the value until the value reaches the highest value, and the IO port becomes a low level; the period of the PWM wave is changed by changing the value of the ARR register, so that the rotating speed of the motor can be changed; by modifying the subdivision number of the controller, the feed rate of the injection tip can be accurate to microns per second.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. A high-precision retina injection device is characterized by comprising a trocar (1) for injection, a metal tube (2) and a stepping motor (3); the injection trocar (1) and the end part of the metal tube (2) are connected with the stepping motor (3), and the metal tube (2) is driven by the stepping motor (3) to do linear motion along the axial direction.

2. A high precision retinal injection device according to claim 1, characterized in that the injection trocar (1) comprises a microneedle (4) and a needle tube (5); the micro-needle (4) is a metal needle tube and is bonded to the tail end of the needle tube (5) through an adhesive, and the needle tube (5) is connected to the tail end of the metal tube (2).

3. A high precision retinal injection device according to claim 1, characterized in that the device is integrally arranged on the housing seat (6); be provided with needle tubing safety cover (7) and step motor seat (8) on shell seat (6), needle tubing safety cover (7) set up in tubular metal resonator (2) the outside, step motor seat (8) set up in step motor (3) bottom.

4. A high precision retina injection device according to claim 3, wherein the needle tube protecting cover (7) is provided with a first linear bearing seat (16) on the side close to the injection trocar (1), the bottom of the first linear bearing seat (16) is arranged on the casing seat (6), the top of the first linear bearing seat (16) is provided with a groove, and the first linear bearing (14) is arranged in the groove; a second linear bearing seat (17) is arranged above the stepping motor seat (8), a through hole is formed in the second linear bearing seat (17), and a second linear bearing (15) is arranged in the through hole.

5. A high precision retinal injection device according to claim 4, characterized in that the output shaft of the stepping motor (3) is connected with a ball screw (9); the end of the ball screw (9) is provided with radial positioning through a radial bearing (10) embedded into the first linear shaft bearing seat (16) in an interference fit mode, and axial positioning is provided through an end cover (11) fixed on the first linear shaft bearing seat (16) through bolts; the terminal (12) is sleeved on the outer side of the ball screw (9), an output shaft of the stepping motor (3) rotates to drive the ball screw (9) to rotate, and the terminal (12) is driven to do linear motion along the ball screw (9) through screw transmission so as to be converted into linear motion of the metal pipe; one side of the terminal (12) is connected to the bottom of the connecting piece (13), the top of the connecting piece (13) is connected with the metal pipe (2), and the terminal (12) moves to drive the connecting piece (13) to move so as to drive the metal pipe (2) to move linearly; the two ends of the metal pipe (2) are radially positioned by a first linear bearing (14) and a second linear bearing (15); in the whole device, a step motor (3) provides motive power to convert the rotation of an output shaft of the step motor (3) into the linear motion of the metal pipe (2).

6. A high precision retinal injection device according to claim 3, characterized in that the housing seat (6) is provided with a first connection bearing seat (18) and a second connection bearing seat (19); the first connecting bearing seat (18) is positioned below the trocar (1) for injection, a through hole is formed in the first connecting bearing seat (18), and a first connecting bearing group (20) is arranged in the through hole; the second connecting bearing seat (19) is arranged below the needle tube protective cover (7), a through hole is formed in the second connecting bearing seat (19), and a second connecting bearing group (21) is arranged in the through hole; the first connecting bearing group (20) and the second connecting bearing group (21) are used for connecting a surgical robot.

7. A high precision retinal injection device according to claim 1 wherein the stepper motor (3) is connected to a control module; the control module comprises a core control unit, a serial port submodule, a motor submodule and an operation submodule;

the motor submodule comprises a stepping motor (3) and a driver, and the driver is used for receiving the signal of the singlechip and then outputting a pulse to control the stepping motor (3).

8. The device of claim 7, wherein the PC is connected to the single chip via a USB port and communicates using a UART serial port; a controller in the control sub-module is connected with the single chip microcomputer through a GPIO port, and the GPIO port serves as an input end and receives a control signal; a PUL port on a driver in the motor submodule is a pulse port and is responsible for controlling the pulse of a driving motor, an ENA port is an enabling port and is responsible for controlling the on-off of the motor, and a DIR port is a direction port and is responsible for controlling the rotation direction of the motor; the connecting line between the driver and the single chip microcomputer adopts a differential connection method, a port PUL-, a port ENA-, a port DIR-and a GND port of the single chip microcomputer are connected with the ground, the port PUL +, the port ENA + and the port DIR + are respectively connected with three GPIO ports of the single chip microcomputer, the three GPIO ports are used as output ends, and the GPIO ports connected with the port PUL + are multiplexed into a timer and used for outputting PWM waves; the stepping motor (3) and the driver adopt a four-wire connection method, and the power supply end of the driver is connected with a direct current power supply.

9. A high precision retinal injection device according to claim 8 wherein the stepper motor (3) is controlled in a pulse-direction mode, the DIR port level changes the direction of rotation, the PUL port outputs a pulse wave to control the motor speed and the number of steps, independently; the PWM output adopts the timer function of a singlechip and adopts an up-counting mode, a CCR register stores a target value, an ARR register stores a highest value, a timer counts according to the system frequency, an IO port outputs a high level when the value reaches the target value, the timer counts and clears the value until the value reaches the highest value, and the IO port becomes a low level; the period of the PWM wave is changed by changing the value of the ARR register, so that the rotating speed of the motor can be changed; by modifying the subdivision number of the controller, the feed rate of the injection tip can be accurate to microns per second.

10. A high accuracy retinal injection device according to claim 9 wherein the control module is programmed to include a mode selection subroutine, a step setting subroutine, a speed control subroutine, a position display subroutine, a direction control subroutine, a return to initial position subroutine; the mode selection subroutine is used for selecting a position control mode and a speed control mode; the step pitch setting subprogram is used for changing the single step pitch of the motor by changing the pulse number in the position control mode; the speed control subprogram is used for changing the speed of the motor by changing the pulse period in a speed control mode; the position display subprogram is used for converting the current position of the motor into the current position of the needle point and returning the current position of the needle point to the PC through the serial port; the direction control subprogram is used for changing the rotation direction of the motor by changing the level of the DIR + port; the return-to-initial position subroutine is used for recording the current position at any time when the motor works and returning to the initial position when a return-to-zero instruction is received.