Stepping type pneumatically-driven small nuclear magnetic compatible navigation positioning robot

Abstract

The invention relates to a stepping type pneumatically-driven small nuclear magnetic compatible navigation positioning robot, and belongs to the technical field of medical surgical robots. The invention aims to provide the pneumatic navigation positioning robot which is miniaturized, low in cost and compatible with nuclear magnetism. According to the robot, accurate motion control is achieved through air cylinder driving and a worm and gear mechanism, calculation and control of postures and positions can be achieved without installing a sensor on an end effector, nuclear magnetic compatibility is guaranteed, and system complexity and manufacturing cost are reduced; meanwhile, the whole structure is compact, the device adapts to the space limitation of a nuclear magnetic cavity, rapid deployment and adjustment in an operation are facilitated, and high-precision brain puncture navigation and positioning operation can be completed under the guidance of nuclear magnetic resonance real-time imaging.

Description

Technical Field

[0001] This invention relates to a small, pneumatically driven, nuclear magnetic resonance compatible navigation and positioning robot, belonging to the field of medical surgical robot technology. Background Technology

[0002] Brain biopsy is a minimally invasive neurosurgical procedure performed within the cranium to target, implant, ablate, or deliver drugs. It is commonly used for stereotactic biopsies, deep brain stimulation (DBS) lead placement, laser-interstitial thermotherapy (LITT), and local drug injection. Traditional methods rely heavily on preoperative imaging combined with stereotactic frames or navigation systems for positioning. Intraoperative real-time soft tissue imaging feedback is lacking, making it difficult to promptly correct errors caused by tissue deformation, changes in patient position, or instrument displacement.

[0003] Magnetic resonance imaging (MRI) provides high-resolution soft tissue images and offers advantages such as being radiation-free and capable of multi-planar imaging, making it widely used in preoperative diagnosis and evaluation. In recent years, advancements in interventional MRI technology have made direct surgical intervention under MRI guidance possible. MRI-compatible surgical robots combine a mechanical operating platform with an interventional MRI system, enabling precise puncture path planning and execution under real-time or near-real-time imaging guidance, thereby improving positioning accuracy and surgical safety.

[0004] Existing MRI-compatible surgical robots vary in their structural form, actuation method, material selection, and control strategy. For example, some commercial platforms (such as the ClearPoint system) have already achieved real-time adjustment of puncture paths and target verification under MRI guidance in clinical applications; some academic prototypes (such as the NeuroArm system) use non-magnetic materials and specially designed actuation units to achieve multi-degree-of-freedom operation in an MRI environment. Regarding actuation, pneumatic actuation is widely used due to the absence of electromagnetic interference and relatively simple structure, but it suffers from response delay and limited control accuracy. Piezoelectric actuation and ultrasonic motors can provide high positioning accuracy, but electromagnetic compatibility optimization is required to reduce imaging artifacts. Furthermore, some studies employ a hybrid structure combining proximal actuation and distal mechanical transmission to balance adaptability to the MRI environment with operational accuracy.

[0005] To ensure NMR compatibility, existing technologies generally use non-magnetic metals (such as titanium alloys and aluminum alloys) and high-strength engineering plastics to manufacture the main structure, and use non-electromagnetic sensors such as fiber optic grating (FBG) sensors and optical encoders to detect displacement, attitude and force.

[0006] Existing technologies utilize a series-parallel combined flexible shaft driven long-arm puncture robot applied in an MRI environment, comprising a pose adjustment module and a puncture module. Its primary purpose is to achieve high-precision, short-time, and highly safe puncture surgery in an MRI environment. The robot's main design involves a long robotic arm extending into the MRI machine to perform the puncture surgery. The series-parallel combination design makes the structure more compact, reducing the robot's occupancy in the MRI space. The robot can move the puncture needle in the X, Y, and Z directions, achieving pitch and yaw, and adjusting the angle and position of the puncture needle. This mechanism has a simple structure and high flexibility, not only reducing puncture surgery time and improving accuracy, but also reaching certain lesions that are inaccessible by traditional puncture techniques.

[0007] The shortcomings of existing technology:

[0008] While existing neurosurgical robots possess some navigation and positioning capabilities in procedures such as brain puncture, they still have the following shortcomings:

[0009] 1. Lack of MRI compatibility: Most commercial and research neurosurgical robots, due to their use of electric drive or the presence of magnetic components, cannot function properly in strong magnetic field environments, making it difficult to combine them with real-time MRI imaging for intraoperative guidance.

[0010] 2. Large size and complex structure: Existing systems are generally large in size, occupying space in the MRI equipment cavity, increasing the difficulty of equipment deployment and adjustment, and limiting their applicability in operating rooms, especially in MRI environments.

[0011] 3. High cost and low clinical adoption rate: The high manufacturing and maintenance costs limit the number of such robots deployed in domestic medical institutions, making it difficult to meet the clinical needs of neurosurgery.

[0012] 4. Strong dependence on sensing of the position and attitude of the end effector: Some existing systems require sensors to be configured at the end effector for position and attitude detection, which not only increases the system complexity and cost, but may also introduce NMR compatibility risks. Summary of the Invention

[0013] The technical problem this invention aims to solve is to provide a miniaturized, low-cost, and MRI-compatible pneumatic navigation and positioning robot, addressing the aforementioned shortcomings. This robot achieves precise motion control through cylinder drive and a worm gear mechanism, eliminating the need for sensors on the end effector to calculate and control attitude and position. This ensures MRI compatibility while reducing system complexity and manufacturing costs. Furthermore, its compact structure adapts to the space constraints of MRI chambers, facilitating rapid deployment and adjustment during surgery. It can perform high-precision brain puncture navigation and positioning operations under real-time MRI imaging guidance.

[0014] The technical solution of this invention is:

[0015] A small, pneumatically driven, stepping-type NMR-compatible navigation and positioning robot is disclosed. The robot comprises a frame structure, a drive structure, a transmission structure, and an execution structure, all made of aluminum or ceramic.

[0016] The frame structure includes bottom components, top components, column components, and horizontal extension components;

[0017] The top assembly includes two top plates and four connecting rods;

[0018] The column assembly includes four columns and one connecting shaft;

[0019] The lateral extension assembly includes eight extension rods distributed along the height of the frame;

[0020] The drive structure is pneumatically driven, with four sets of drive units on each side of the frame structure;

[0021] The transmission structure consists of a swing arm linkage mechanism and a worm gear mechanism;

[0022] The actuation structure consists of two identical four-bar linkages at the upper and lower levels, as well as a puncture needle catheter.

[0023] Beneficial effects

[0024] 1. Nuclear magnetic resonance compatible mechanical structure design

[0025] All mechanical components, including the frame, drive, transmission, and actuator, are made of non-magnetic and non-conductive materials (such as rubber telescopic cylinders and adhesive connections) to ensure safe use in a nuclear magnetic resonance environment.

[0026] 2. Demountable and modular frame structure

[0027] The bottom component, top component, column component, and lateral extension component can be quickly disassembled and adjusted via set screws and plug-in rods, facilitating transportation, installation, and adaptation to surgical environments.

[0028] 3. Pneumatic dual-degree-of-freedom drive unit

[0029] The combination of horizontal and vertical cylinders enables precise movement of the slider within a rectangular trajectory, and the pneumatic components are entirely composed of rubber telescopic tubes to avoid magnetic interference.

[0030] 4. Slider drive and swing arm-worm gear composite transmission structure

[0031] The slider drives the swing arm, which, through the worm gear and worm wheel, achieves 90° interlaced shaft transmission, converting the two-dimensional pneumatic linear motion into rotational motion, and driving a multi-stage four-bar linkage mechanism.

[0032] 5. Two-stage four-bar linkage actuator

[0033] The upper and lower two-stage four-bar linkage structure is connected in parallel, and the three-dimensional position and attitude of the puncture needle cannula are adjusted through worm gear transmission, thereby improving positioning accuracy and flexibility. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the composition of the small nuclear magnetic compatibility navigation and positioning robot of the present invention;

[0035] Figure 2 This is a schematic diagram of the frame structure;

[0036] Figure 3 This is a schematic diagram of the driving structure;

[0037] Figure 4 This is a schematic diagram of the transmission structure;

[0038] Figure 5 This is a schematic diagram of the execution structure. Detailed Implementation

[0039] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0040] Example

[0041] like Figure 1 As shown, the present invention mainly consists of four parts: frame structure 1, drive structure 2, transmission structure 3 and execution structure 4. All materials are made of aluminum or ceramic to ensure NMR compatibility.

[0042] like Figure 2 As shown, frame structure 1 includes a bottom component, a top component, a column component, and a horizontal extension component;

[0043] The bottom assembly includes base plates 101, 102, and 103, which are connected by connecting rods 112, 113, 114, and 115. The two ends of the connecting rods are inserted into the mounting holes of the corresponding base plates and locked by set screws on the sides of the base plates, thereby reliably fixing the connecting rods to the base plates.

[0044] The top assembly includes top plates 110 and 111, which are connected by smooth connecting rods 119, 120, 121 and 124. The two ends of the connecting rods are inserted into the mounting holes of the corresponding top plates, and the connecting rods and the top plates are also fixed by set screws.

[0045] The column assembly includes columns 104, 105, 106, 107, 108, and 109, and also includes a connecting shaft 127. The upper and lower ends of the columns are connected to the connecting rods respectively, and are also fixed in position by set screws on the side of the columns. The connecting shaft 127 passes through the center holes of the base plate 102 and the top plate 110, and is fixed in position by set screws on its side.

[0046] The lateral extension assembly includes multiple extension rods 116, 117, 118, 119, 122, 123, 125, and 126 distributed along the height of the frame. They are all fixed to the column by set screws, with one end extending outward for mounting other components.

[0047] like Figure 3 As shown, the drive structure is pneumatically driven, with four sets of drive units on each side of the frame structure 1. Taking the drive unit on the upper side of the figure as an example;

[0048] The drive unit includes a lateral cylinder and a longitudinal cylinder;

[0049] The transverse cylinder consists of a cylinder bracket 211, a piston 213, a cylinder 214, and a connecting nozzle 215. The extension sides of extension rods 118 and 119 pass through the cylinder bracket 211 and are fixed by set screws on the cylinder bracket 211. The piston 213 is installed between the extension rods 118 and 119, with a clearance fit between the bore and shaft, allowing the piston 213 to slide freely on the extension rods 118 and 119. One side of the cylinder 214 is fixedly connected to the piston 213 with adhesive, and the other side is fixedly connected to the connecting nozzle 215 with adhesive. The cylinder (including all cylinders described below) is made of rubber telescopic tubing, which can extend or retract. The connecting nozzle 215 is mounted on the cylinder bracket 211 and fixedly connected with adhesive.

[0050] The longitudinal cylinder consists of a sliding cylinder bracket 201, a piston 204, a cylinder 203, a connecting nozzle 202, a connecting rod 205, a slider 206, a cylindrical drive pin 210, a guide rod 207, a guide rod 208, and an end plate 209. The sliding cylinder bracket 201 is mounted on extension rods 118 and 119 with a clearance fit, allowing the sliding cylinder bracket 201 to slide freely on the extension rods 118 and 119. The connecting nozzle 202 is mounted on the sliding cylinder bracket 201 and fixedly connected by adhesive. One side of the cylinder 203 is fixedly connected to the connecting nozzle 202 by adhesive, and the other side is fixedly connected to the piston 204 by adhesive. The guide rods 207 and 208 are mounted on the lower side of the sliding cylinder bracket 201 and fixedly connected by adhesive. The other side of the guide rods 207 and 208 is connected to the end plate 209 by adhesive. The slider 206 is mounted on guide rods 207 and 208 with a clearance fit between the hole and shaft, allowing it to slide freely on the guide rods 207 and 208. The cylindrical drive pin 210 is fixedly mounted on the slider 206 with adhesive. The slider 206 and piston 204 are connected by a connecting rod 205, also secured with adhesive. Between the transverse and longitudinal cylinders, the sliding cylinder bracket 201 is connected to the piston 213 of the transverse cylinder via a connecting rod 212, also secured with adhesive.

[0051] like Figure 4 As shown, the transmission structure 3 consists of a swing arm linkage mechanism and a worm gear mechanism. The swing arm linkage mechanism comprises a cylindrical drive pin 210 and a swing arm 301, while the worm gear mechanism comprises a worm shaft 302, a worm 303, and a worm wheel 304. The cylindrical drive pin 210, fixed to the slider 206, meshes with the clearance groove of the swing arm 301. One end of the swing arm 301 is fixedly connected to one end of the worm shaft 302 by adhesive. The worm shaft 302 is installed between columns 108 and 109 and connected by bearings, allowing it to rotate freely axially. The worm 303 is fixedly connected to the worm shaft 302 by adhesive and is located between columns 108 and 109. The worm 303 meshes with the worm wheel 304, forming a 90° staggered shaft transmission.

[0052] like Figure 5As shown, the execution structure 4 consists of two identical four-bar linkages and a puncture needle guide. Connected in series on the connecting shaft 127, the worm gear 307 is axially fixed to both ends of the vertically mounted connecting shaft 217 via a top plate 110 and a bottom plate 102. Worm gears 304, 305, 306, and 307 are sequentially mounted on the shaft. Worm gears 307 and 306 are in close contact with each other and separated from the top plate 110 by a sleeve 412. Worm gears 305 and 304 are in close contact with each other and separated from worm gear 306 by a sleeve 413. Each worm gear is tightly fitted to the sleeve, and the sleeve is tightly fitted to the end plate. The axial spacing and positional relationship between the gears are precisely controlled by the lengths of sleeves 412 and 413. Figure 5 Taking the upper-middle four-bar linkage as an example, the four-bar linkage consists of active positioning arms 401 and 402, passive positioning arms 403 and 404, an end cap 405, and a spherical bearing 406. One end of the active positioning arm 401 is annular, and the annular end is clearance-fitted with the stepped part of the worm gear 307, allowing it to rotate freely. It is then fixedly connected to the worm gear 307 by a set screw 408. Loosening the set screw 408 allows the position of the active positioning arm 401 to be adjusted, while tightening the set screw 408 allows the active positioning arm 401 to rotate with the worm gear 307. The same applies to the active positioning arm 402. The passive positioning arm 404 is connected to the active positioning arm 401 by a positioning pin 411 and two bearings, allowing the passive positioning arm 404 to rotate freely around the connection point. The same applies to the passive positioning arm 403. The passive positioning arm 404 has a hollow cylindrical stepped structure at its end, while the passive positioning arm 403 has an annular structure at its end. The annular structure and the hollow cylindrical stepped structure form a clearance fit, allowing for free relative rotation between them. An end cap 405 is fitted to the annular end of the passive positioning arm 403 and engages with the hollow cylindrical stepped structure of the passive positioning arm 404 via a threaded connection, thereby constraining the axial position of the mating pair. A spherical bearing 406 is installed at the center of the hollow cylinder at the end of the passive positioning arm 403 via an interference fit. The puncture needle guide tube 407 passes through the end spherical bearings 406 and 414 of the upper and lower four-bar linkages and is fixed in position via an interference fit.

[0053] When both the horizontal and vertical cylinders are evacuating air, cylinder 214 shortens, causing piston 213 to slide to the right. Piston 213 is fixedly connected to the vertical cylinder, so the entire vertical cylinder slides to the right. Cylinder 203 shortens, causing piston 204 to slide upwards. Piston 204 is fixedly connected to slider 206, so slider 206 slides upwards, currently positioned in the upper right corner. When the horizontal cylinder is evacuating air and the vertical cylinder is inflating air, cylinder 214 remains in the same state. Cylinder 203 extends, causing piston 204 to slide downwards. Piston 204 is fixedly connected to slider 206, so slider 206 slides downwards, currently positioned in the lower right corner. When the horizontal cylinder is inflating air and the vertical cylinder is inflating air, cylinder 214 shortens, causing piston 213 to slide to the left. Piston 213 is fixedly connected to the vertical cylinder, so the entire vertical cylinder slides to the left. Cylinder 203 remains in the same state, and the vertical position of slider 206 remains unchanged, currently positioned in the lower left corner. When the transverse cylinder is inflated and the longitudinal cylinder is pumping air, cylinder 214 remains in a constant state. Cylinder 203 shortens, causing piston 204 to slide upwards. Piston 204 is fixedly connected to slider 206, so slider 206 slides upwards, currently positioned at the upper left corner. During this process, the transverse cylinder determines the transverse position of slider 206, and the longitudinal cylinder determines its longitudinal position. Through this cycle, slider 206 moves in a rectangular trajectory clockwise (similarly, it can also move counter-clockwise).

[0054] When the slider 206 moves along a rectangular trajectory in a clockwise direction, the cylindrical drive pin 210, which is fixedly connected to the slider 206, also moves accordingly. Since it meshes with the swing arm 301 through the clearance groove, it drives the swing arm 301 to perform circumferential motion, which in turn drives the worm shaft 302 and the worm 303 to rotate axially. Through the worm gear transmission structure, it drives the worm wheel 304 to rotate.

[0055] Taking the upper four-bar linkage as an example, the transmission structure drives the worm gears 306 and 307 to rotate. With the set screw tightened, the active positioning arms 401 and 402 rotate accordingly, and the passive positioning arms 404 and 403 also rotate, ultimately changing the position of the end joint bearing 406. Similarly, this can also change the position of the end joint bearing 414 of the lower four-bar linkage. The changes in the positions of the joint bearings 406 and 414 also change the position and orientation of the puncture needle guide 407. By controlling the puncture needle guide to the target position and orientation, needle insertion or other surgical procedures can be performed.

[0056] Technical basis and effects of improving MRI compatibility, achieving small size and easy deployment

[0057] Key technical implementation points:

[0058] a. The drive and actuation components should be made of non-magnetic and non-conductive materials and mechanical transmission (cylinders 214 and 203 are rubber telescopic tubes, connected with adhesive, and metal parts are made of non-magnetic materials), and no electrical drive or sensor should be placed at the end (the puncture needle catheter 407 is directly positioned by a mechanical four-bar linkage).

[0059] b. A modular frame (base plate 101–103, column 104–109, extension rod 116–126, set screw connection) is used to achieve detachable and compact configuration.

[0060] The resulting technical effects:

[0061] a. Significantly reduce magnetization and induced current sources in the MRI environment, reduce imaging artifacts and safety hazards, thereby meeting the compatibility requirements of interventional MRI surgery;

[0062] b. Modular and low-profile design facilitates placement and disassembly within the narrow cavity of the MRI scanner, reducing deployment time and improving clinical usability.

[0063] The basis is:

[0064] Non-electrical, non-magnetic materials and the physical causal relationship between them and the end-device electrical components reduce artifacts; modular components can be quickly assembled through set screws, which is significantly better than the deployment limitations of large integrated robotic arms in confined spaces.

[0065] Achieving high-precision positioning and attitude control without relying on end sensors.

[0066] Key technical implementation points:

[0067] a. Two-stage motion division of labor: the pneumatic transverse cylinder 214 and the longitudinal cylinder 203 realize the coarse positioning (rectangular trajectory) of the slider 206, limiting the uncertainty of pneumatic drive to large stroke and low frequency components;

[0068] b. Mechanical speed reduction and precise rotation: The slider drives the upper / lower four-bar linkage (401–404) via cylindrical drive pin 210 → swing arm 301 → worm shaft 302 / worm 303 → worm wheel 304 to make precise angle adjustments to the needle guide 407. The worm wheel and worm structure has a high speed reduction ratio and self-locking characteristics;

[0069] The resulting technical effects:

[0070] a. By combining the less precise pneumatic displacement with the more precise mechanical angle adjustment, the effects of pneumatic nonlinearity and hysteresis are limited to the coarse positioning stage, while the high-precision positioning is placed in the worm gear (mechanical reduction) stage, thus achieving higher final resolution and repeatability.

[0071] b. The high reduction ratio and self-locking property of the worm gear ensure that the needle guide has a good holding force when the air source is cut off or when it remains static, reducing the backlash or drift caused by tissue reaction force or pipeline pressure fluctuations, and improving the stability of the endpoint.

[0072] c. By replacing the end sensor with rigid kinematics inverse calculation, "precise positioning without end sensors" can be achieved, thereby reducing system complexity and NMR compatibility risks.

[0073] Supported data:

[0074] a. The mechanical structure can achieve a rotational resolution of 1.5°;

[0075] b. Trajectory tracking experiment results: The average error of the linear trajectory is 0.2015 mm, and the theoretical average error of the circular track is 0.7538 mm. These values ​​indicate that the mechanical transmission and kinematic control can achieve sub-millimeter to sub-millimeter level accuracy, demonstrating that this scheme can indeed output high-precision end pose. (See the paper for specific experiments)

[0076] Improve system stability, responsiveness, and clinical usability (including advantages in cost and safety).

[0077] Key technical implementation points:

[0078] a. Self-locking transmission and mechanical braking: The worm gear (302, 304) provides braking / self-locking effect in the transmission chain; the set screw (such as 408) achieves mechanical locking of the position of the drive arm; the four-bar linkage and bearings (spherical bearings 406, 414) adopt interference / tight fit to ensure rigid connection.

[0079] b. Simple and reliable pneumatic unit and modular design: The cylinder adopts a rubber telescopic tube, sliding bracket and connecting rod fixed with clearance fit / set screw, which has low manufacturing cost and is easy to replace.

[0080] The resulting technical effects:

[0081] a. Self-locking and mechanical locking reduce the risk of displacement drift caused by air pressure fluctuations or power abnormalities during operation, improving surgical safety and the ability to maintain accuracy;

[0082] b. The low-complexity design of pneumatic components and adhesive / mechanical cooperation leads to a controllable reduction in manufacturing and maintenance costs, which is conducive to clinical promotion and domestic application;

[0083] Reduced energy consumption and pressure control burden: The worm gear self-locking and mechanical holding means that it is not necessary to continuously maintain high air pressure to maintain the position, reducing air source energy consumption and alleviating dependence on high-precision air source valve control;

[0084] Easy to sterilize and replace consumables: Modular and simple materials make it easier to design patient-contacting parts (such as puncture needle catheter support components) as replaceable / sterilizable parts, which facilitates clinical process management;

[0085] Cost advantages: Using rubber telescopic tubes, clearance fit structures, and mechanical transmissions instead of expensive precision motors and complex sensors can significantly reduce manufacturing and maintenance costs, and promote the accessibility of equipment in the domestic market.

[0086] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A small nuclear magnetic resonance compatible navigation positioning robot driven by step-by-step pneumatic drive, characterized in that: the small nuclear magnetic resonance compatible navigation positioning robot comprises a frame structure, a driving structure, a transmission structure and an execution structure, and all materials are selected from aluminum or ceramics.

2. The small nuclear magnetic resonance compatible navigation positioning robot driven by step-by-step pneumatic drive according to claim 1, characterized in that: the frame structure comprises a bottom assembly, a top assembly, a column assembly and a transverse extension assembly; the bottom assembly comprises three bottom plates, the three bottom plates are connected by four connecting rods, the two ends of the four connecting rods are inserted into the mounting holes of the corresponding bottom plates, and the four connecting rods are fixed with the three bottom plates by locking the set tight screws on the side edges of the bottom plates.

3. The small nuclear magnetic resonance compatible navigation positioning robot driven by step-by-step pneumatic drive according to claim 2, characterized in that: the top assembly comprises two top plates and four connecting rods, the two top plates are connected by the four connecting rods, the two ends of the four connecting rods are inserted into the mounting holes of the corresponding top plates, and the four connecting rods and the two top plates are fixed by the tight screws, so that the four connecting rods are fixed with the two top plates.

4. The small nuclear magnetic resonance compatible navigation positioning robot driven by step-by-step pneumatic drive according to claim 3, characterized in that: the column assembly comprises four columns and a connecting shaft, the upper ends of the four columns are connected with the connecting rods of the top assembly, the lower ends of the four columns are connected with the connecting rods of the bottom assembly, and the positions are fixed by the tight screws on the side edges of the columns, the connecting shaft 127 passes through the center holes of one of the bottom plates and the corresponding top plates above and below, and the position is fixed by the tight screws.

5. The small nuclear magnetic resonance compatible navigation positioning robot driven by step-by-step pneumatic drive according to claim 4, characterized in that: the transverse extension assembly comprises eight extension rods distributed along the height direction of the frame, one end of the eight extension rods is fixed on the columns in the column assembly by the tight screws, and the other end of the eight extension rods extends outward.

6. The small nuclear magnetic resonance compatible navigation positioning robot driven by step-by-step pneumatic drive according to claim 5, characterized in that: the driving structure adopts pneumatic drive, and there are four groups of driving units on both sides of the frame structure; the driving unit comprises a transverse air cylinder and a longitudinal air cylinder; the transverse air cylinder is composed of a cylinder support, a piston, an air cylinder and a connecting nozzle, the extension side of the extension rod passes through the cylinder support and is fixed by the tight screws on the cylinder support; the piston is installed between the two extension rods, the hole shaft cooperation is clearance fit, so that the piston can freely slide on the two extension rods, one side of the air cylinder is fixedly connected with the piston by adhesive, the other side of the air cylinder is fixedly connected with the connecting nozzle by adhesive, the air cylinder is made of rubber expansion pipe and can be elongated or shortened, the connecting nozzle is installed on the cylinder support and is fixedly connected by adhesive. ​ ​ ​ ​ ​ ​ The longitudinal cylinder is composed of a sliding cylinder support, a piston, a cylinder, a connecting nozzle, a connecting rod, a sliding block, a cylindrical drive pin, two guide rods and an end plate. The sliding cylinder support is installed on the two extension rods in clearance fit, so that the sliding cylinder support can freely slide on the two extension rods. The connecting nozzle is installed on the sliding cylinder support and fixedly connected by adhesive. One side of the cylinder is fixedly connected with the connecting nozzle by adhesive, and the other side of the cylinder is fixedly connected with the piston by adhesive. One end of the two guide rods is installed on the lower side of the sliding cylinder support and fixedly connected by adhesive. The other end of the two guide rods is connected with the end plate by adhesive. The sliding block is installed on the two guide rods in clearance fit, so that the sliding block can freely slide on the two guide rods. The cylindrical drive pin is fixedly installed on the sliding block by adhesive. The sliding block is connected with the piston by the connecting rod and fixedly connected by adhesive. The sliding cylinder support is connected with the piston of the transverse cylinder by the connecting rod and fixedly connected by adhesive.

7. The stepping pneumatic drive small nuclear magnetic compatible navigation positioning robot according to claim 6, characterized in that: The transmission structure is composed of a swing arm linkage mechanism and a worm gear mechanism; The swing arm linkage mechanism is composed of a cylindrical drive pin and a swing arm; The worm gear mechanism is composed of a worm shaft, a worm and a worm gear; The cylindrical drive pin fixed on the sliding block is engaged with the clearance groove of the swing arm, and the swing arm is fixedly connected with one end of the worm shaft by adhesive; the worm shaft is installed between the two vertical columns and connected by bearings, and can freely rotate in the axial direction; the worm is fixedly connected with the worm shaft by adhesive and is located between the two vertical columns; the worm and the worm gear are engaged with each other to form a 90° staggered shaft transmission.

8. The stepping pneumatic drive small nuclear magnetic compatible navigation positioning robot according to claim 7, characterized in that: The execution structure is composed of two levels of identical four-bar linkages and puncture needle catheters, which are connected in series on the connecting shaft. The worm gears are axially fixed at both ends of the connecting shaft by the top plate and the bottom plate. Four worm gears are installed on the shaft in sequence, two of which are mutually adhered as the first group and separated from the top plate by a sleeve, and the other two are mutually adhered as the second group and separated from the worm gears of the first group by a sleeve. The worm gears and the sleeves are connected by tight fit, and the axial spacing and positional relationship between the gears are controlled by the length of the sleeves.

9. The stepping pneumatic drive small nuclear magnetic compatible navigation positioning robot according to claim 8, characterized in that: The four-bar linkage mechanism is composed of two active positioning arms, two passive positioning arms, end caps and joint bearings; One end of the active positioning arm is annular, and the annular end is clearance fitted between the steps of the worm gears, which can freely rotate and are fixedly connected with the worm gears by a locking screw. When the locking screw is loosened, the position of the active positioning arm can be adjusted, and when the locking screw is tightened, the active positioning arm can rotate with the worm gears. The passive positioning arm is connected with the active positioning arm by a positioning pin and two bearings, and can freely rotate around the connection. One of the passive positioning arm end is provided with a hollow cylindrical stepped structure, and the other passive positioning arm end is configured as a circular ring structure; The circular ring structure and the hollow cylindrical stepped structure form a clearance fit pair to realize the free relative rotation between them; The end cover is assembled on the circular ring end of the passive positioning arm and is matched with the hollow cylindrical stepped structure of the passive positioning arm through a threaded connection, thereby realizing the axial position constraint of the fit pair; the joint bearing is installed at the center position of the end hollow cylinder of the passive positioning arm through interference fit, and the puncture needle guide tube passes through the two end joint bearings of the upper and lower two-stage four-bar linkage mechanism and is fixed in position through interference fit.

10. The stepping pneumatic drive small nuclear magnetic compatible navigation positioning robot according to claim 8, characterized in that: When the transverse cylinder is exhausted and the longitudinal cylinder is exhausted, the cylinder shortens to drive the piston to slide to the right, the piston is fixedly connected with the longitudinal cylinder, so that the longitudinal cylinder as a whole slides to the right; the cylinder shortens to drive the piston to slide upward, the piston is fixedly connected with the slider, and the slider slides upward, at this time, the slider is at the upper right corner; when the transverse cylinder is exhausted and the longitudinal cylinder is exhausted, the cylinder state remains unchanged; the cylinder elongates to drive the piston to slide downward, the piston is fixedly connected with the slider, and the slider slides downward, at this time, the slider is at the lower right corner; When the transverse cylinder is exhausted and the longitudinal cylinder is exhausted, the cylinder shortens to drive the piston to slide to the right, the piston is fixedly connected with the longitudinal cylinder, so that the longitudinal cylinder as a whole slides to the right; the cylinder state remains unchanged, the longitudinal position of the slider remains unchanged, at this time, the slider is at the lower left corner; When the transverse cylinder is exhausted and the longitudinal cylinder is exhausted, the cylinder shortens to drive the piston to slide to the right, the piston is fixedly connected with the longitudinal cylinder, so that the longitudinal cylinder as a whole slides to the right; the cylinder state remains unchanged, the longitudinal position of the slider remains unchanged, at this time, the slider is at the lower left corner; In this process, the transverse cylinder determines the transverse position of the slider, and the longitudinal cylinder determines the longitudinal position of the slider, and the slider moves along a rectangular trajectory in a clockwise direction through such a cycle; When the slider moves along a rectangular trajectory in a clockwise direction, the cylindrical drive pin fixedly connected with the slider also moves, and since the cylindrical drive pin engages with the swing arm through the gap groove, the swing arm is driven to perform a circular motion, further driving the worm shaft and the worm to rotate axially, and driving the worm gear to rotate through the worm gear transmission structure; Through the transmission of the transmission structure, the worm gear is driven to rotate, and in the case that the set screw is tightened, the driving positioning arm is driven to rotate, the passive positioning arm is also driven to rotate, and finally the position of the end joint bearing is changed, and the position and posture of the puncture needle guide tube are also changed.

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