CN114699142A

CN114699142A - Pneumatic rigidity-variable six-freedom-degree CT-MRI needle puncture robot

Info

Publication number: CN114699142A
Application number: CN202210220189.XA
Authority: CN
Inventors: 雷勇; 王真
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2022-03-08
Filing date: 2022-03-08
Publication date: 2022-07-05

Abstract

The invention discloses a pneumatic rigidity-variable six-freedom-degree CT-MRI needle puncture robot. The device comprises a plane positioning module, a pneumatic posture adjusting module and a needle inserting module. The plane positioning module drives the locking stator sliding block to move in the moving female sliding block through pneumatic muscles to complete the locking and the unlocking of the movement of the moving female sliding block; the pneumatic posture adjusting module is in an inflation and deflation state in the air bag to limit the rotational freedom degree of the puncture needle on the spherical hinge; the needle inserting module drives the steering gear through the long gear column to realize the rotation angle control of the puncture needle around the needle shaft, and simultaneously drives the needle inserting slide block to linearly move along the screw rod through the rotation of the screw rod to realize the degree of freedom of the needle inserting of the puncture needle. The invention has compact structure and simple control, the processing materials are all non-metallic materials, the CT-MRI is compatible, the posture fixation of the puncture needle is realized by utilizing pneumatics, and the quantitative needle insertion is realized by utilizing a ceramic motor, a wire drive mechanism or manual drive.

Description

Pneumatic rigidity-variable six-freedom-degree CT-MRI needle puncture robot

Technical Field

The invention belongs to a puncture robot in the field of manufacturing and application of medical instruments, and particularly relates to a pneumatic rigidity-variable six-degree-of-freedom CT-MRI needle puncture robot.

Background

Clinically, if a lesion is found in the lung by CT examination, but it is not certain whether it is caused by infection, non-pathological infection or tumor, and particularly malignant tumor cannot be excluded, a lung biopsy is required to determine the nature of the lesion. Lung puncture is also a routine examination of some tissues taken by puncturing to a lesion under the positioning of CT. However, CT guided puncture also has disadvantages: for example, because the images are not displayed in a timely manner, the breathing movement can cause errors in accurate positioning, and the patient must be trained to know the breathing phase. When the puncture needle needs to form a certain angle with the cross section, the puncture technology has certain difficulty, so that the pose of the puncture needle needs to be continuously adjusted through a CT image. However, the generation of the CT images requires a certain time, and the observation of the CT images requires leaving the operating table. Therefore, in the process of lung puncture surgery, the pose of the puncture needle needs to be continuously adjusted according to the CT image before the puncture needle enters the process, and after the pose is preliminarily determined, a doctor pastes positioning paper in a proper place to preliminarily determine the position of the puncture point. Therefore, the surgeon needs to constantly adjust the puncture needle and then fix the puncture needle. After the initial positioning is completed, the doctor needs to leave the operating room, and perform CT scanning again on the patient to determine the needle inserting direction and angle and finally determine the puncture point. After the needle is inserted and the puncture needle enters the preset depth, CT scanning is needed again to determine the position of the needle point; if the needle tip does not reach the focus, the adjustment is needed according to the scanning result, and the puncturing is finished finally by repeating the steps. Most medical personnel fix half of the puncture needle on the patient by puncturing the positioning needle. However, the puncture needle is driven to move together under the respiration action of the patient, and the puncture needle is easy to shift and even fall off during the operation. Finally, the problems of operation failure, inaccurate positioning, excessive lung tissue removal and the like are caused. The existing solution of medical staff is to directly adopt a tape or gauze winding and fixing mode, and partially adopt a gantry support arranged on an operating table to fix a puncture needle. But this is often poor due to patient respiration. It is difficult to actually fix the puncture needle. And a medical staff cannot be arranged for manual fixation because the medical staff cannot be under the ray for a long time due to the health reasons of the medical staff and the CT scanning process cannot be interfered. Therefore, at present, a small puncture needle fixing device which can be attached to a patient needs to be developed urgently, and the fixing device needs to realize the movement with multiple degrees of freedom, so that a doctor can conveniently realize the control of the movement track of the puncture angle of the puncture needle and the fixation of the puncture needle in the puncture process.

Since the fixing device is used for liver puncture operation in practical application, the device needs to realize movement in a plane of 100mm x 100mm so as to ensure that the puncture needle can puncture any position. Meanwhile, the uncertainty of the puncture position often needs to control not only the plane position of the puncture needle, but also the spatial posture of the puncture needle, namely the puncture angle. The fixation device also requires control of the needle's angle of oscillation. However, the excessive freedom of control means a more complicated actuator and the fixation device must be attached to the patient's chest, so the device needs to be compact. Therefore, under the condition of ensuring normal use, the device can control four degrees of freedom of the puncture needle so as to realize movement along a horizontal plane, rotation in a vertical plane and rotation in the horizontal plane. Finally, in the actual puncture process, the puncture depth and the puncture rotation angle of the puncture needle also influence the hit precision, so that a module for controlling the quantitative rotation and the puncture depth of the puncture needle is additionally added on the basis of the four-degree-of-freedom fixation.

SUMMARY OF THE PATENT FOR INVENTION

In order to realize the functions required to be realized in the background technology, the invention provides a pneumatic rigidity-variable six-freedom-degree CT-MRI needle puncture robot. The six-degree-of-freedom auxiliary fixing puncture needle can be provided to assist a doctor to complete accurate fixing of puncture of a biopsy needle in a CT-MRI working environment, so that the control capability of the doctor on the puncture needle in an operation process is improved, and meanwhile, the puncture robot is not influenced by respiratory motion of a patient in the puncture process.

The technical scheme adopted by the invention is as follows:

the invention mainly comprises a two-degree-of-freedom plane positioning module, a two-degree-of-freedom attitude fixing module and a two-degree-of-freedom rotary needle inserting module; the two-degree-of-freedom posture fixing module is installed on the two-degree-of-freedom plane positioning module, the two-degree-of-freedom rotary needle feeding module is installed on the two-degree-of-freedom posture fixing module, and the biopsy needle is installed on the two-degree-of-freedom rotary needle feeding module.

The two-degree-of-freedom plane positioning module comprises a base, a plane positioning mechanism and a posture fixing mechanism; the two bases are arranged in parallel and oppositely at intervals, the two ends of each base are respectively provided with an adapter, a plane positioning mechanism is arranged between the two ends of each base, and each plane positioning mechanism comprises a carbon fiber tube, a locking strip and a female sliding block; the two carbon fiber tubes penetrate through the female slider in parallel and relatively at intervals and then are fixedly connected to one ends of the two bases through the adaptor, the two locking strips penetrate through the female slider in parallel and relatively at intervals and then are fixedly connected to one ends of the two bases through the adaptor, and the two locking strips are positioned below the carbon fiber tubes and are respectively placed in parallel and relatively at intervals with the two carbon fiber tubes; and a posture fixing mechanism with the structure basically the same as that of the plane positioning mechanism is also arranged between the female sliding blocks of the two plane positioning mechanisms, the female sliding block in the posture fixing mechanism is used as the female sliding block of the needle base, and the carbon fiber tube and the locking strip in the posture fixing mechanism are fixedly connected to the two female sliding blocks.

The female slider and the needle base female slider are hollow, and an air guide pipe, pneumatic muscles, a tension rope and two sub locking sliders are horizontally arranged in the female slider and the needle base female slider respectively and vertically to the sliding direction of the female slider and the needle base female slider; the pneumatic muscle and the pull rope are positioned between the two sub-locking sliding blocks, and the air guide pipe is arranged on the pneumatic muscle; after the air duct inflates the pneumatic muscle, the pneumatic muscle begins to expand to push the sub locking sliding blocks to move in the female sliding block or the female sliding block of the needle base to two sides until the serrated surface arranged on the outer side of the locking sliding block is overlapped with the serrated surface arranged on the inner side of the locking strip to form structural limit, the female sliding block or the female sliding block of the needle base is fixed at the current position, and meanwhile, the tension rope is tensioned; when the pneumatic muscle does not work, the sub-locking sliding blocks on the two sides are tensioned towards the inner side by the tension rope, the sawtooth surfaces on the outer sides of the sub-locking sliding blocks are separated from the sawtooth surfaces on the inner sides of the locking strips, and the female sliding blocks or the female sliding blocks of the needle bases are released from the structure for limiting.

The two female sliding blocks and the needle seat female sliding block both take the carbon fiber tube as a guide rail and freely slide along the carbon fiber tube; the female slider of female slider and the female slider of needle file all with the upper and lower face sliding contact of locking strip in order to freely slide along the locking strip, with the inboard sawtooth surface contactless of locking strip.

The posture fixing mechanism also comprises a spherical hinge which is sleeved at the central position inside the needle seat female sliding block and is movably connected with the needle seat female sliding block;

the two-degree-of-freedom posture fixing module comprises a locking air bag base, a locking air bag, a puncture needle sleeve and air bag locking particles; the puncture needle sleeve sequentially penetrates through the central through holes of the locking air bag, the locking air bag base and the needle seat female sliding block from top to bottom and is fixedly installed on a spherical hinge installed inside the needle seat female sliding block; the locking air bag base is fixedly installed on the upper portion of the needle seat female sliding block, the locking air bag is fixedly installed on the air bag base, an air inlet pipe is arranged on the side face of the locking air bag, a plurality of air bag locking particles are arranged inside the locking air bag, and the locking air bag is connected with an external vacuum pump through the air inlet pipe.

The two-degree-of-freedom rotary needle inserting module comprises a needle inserting module lower fixing seat, a carbon fiber tube B, a needle inserting sliding block, a boss gear, a screw rod, a gear limiting part, a biopsy needle, a needle inserting module upper limiting seat, a coupler and a long gear column; the upper limiting seat of the needle inserting module is positioned right above the lower fixing seat of the needle inserting module, the lower fixing seat of the needle inserting module and the upper limiting seat of the needle inserting module are connected through a vertical carbon fiber tube B, a screw rod and a long gear column are parallel to the carbon fiber tube B and are vertically arranged between the lower fixing seat of the needle inserting module and the upper limiting seat of the needle inserting module, and the upper ends of the screw rod and the long gear column penetrate through the upper limiting seat of the needle inserting module and are connected with an external driving source through respective couplers;

a needle inserting sliding block is arranged between the upper limiting seat of the needle inserting module and the lower fixing seat of the needle inserting module, a boss gear is hinged on the needle inserting sliding block, a central through hole is formed in the needle inserting sliding block, and the biopsy needle sequentially penetrates through the central through hole of the needle inserting sliding block from bottom to top and then is fixedly sleeved on the through hole where the central axis of the boss gear is located;

the two-degree-of-freedom rotary needle inserting module further comprises a gear limiting part, the needle inserting sliding block is provided with the gear limiting part used for protecting the gear of the boss, and the biopsy needle simultaneously and movably penetrates through a through hole formed in the gear limiting part.

The needle inserting sliding block and a screw form a rotary pair through internal threads arranged on the side face, the screw rotates to drive the needle inserting sliding block to do linear motion along the axis direction of the screw, the biopsy needle sequentially penetrates through a gear limiting part, a boss gear and a central through hole of the needle inserting sliding block from top to bottom and then is fixedly sleeved on a central axis of the boss gear, the boss gear is meshed and connected with a long gear column to form a gear pair, the long gear column drives the boss gear to do circumferential rotation through the gear pair so as to drive the biopsy needle to rotate around the axis of the biopsy needle, and the biopsy needle penetrates through a needle inserting module support and then continuously penetrates through a puncture needle sleeve to finally reach a target human body; and the lower fixing seat of the needle inserting module in the needle inserting module bracket is downwards connected to the locking air bag.

The locking air bag utilizes negative pressure contraction to limit the flowability of air bag locking particles in the locking air bag, and the puncture needle sleeve is controlled to be fixed in any posture.

The long gear column is matched with the boss gear to control the biopsy needle to rotate quantitatively at an angle; the screw rod is matched with the needle insertion slider to control the needle insertion length of the biopsy needle so as to realize quantitative needle insertion.

The whole mechanism is made of non-metal materials.

The two-degree-of-freedom rotary needle inserting module is externally connected with a ceramic machine and a wire driving mechanism through a coupler to realize machine driving or directly driven manually to realize man-machine switching.

The spherical hinge is movably connected with the needle seat female sliding block inside the needle seat female sliding block to form a revolute pair.

The invention has the beneficial effects that:

all parts of the invention are made of non-metallic materials, thereby ensuring that no metal compact objects exist in the CT section and the MRI during the needle puncture operation, and being compatible with CT-MRI equipment to realize CT-MRI imaging.

The invention adopts a modular design idea, and the three sub-modules have no dependency and can be used independently.

According to the principle that the flowability of particles in the air bag is reduced under the pneumatic negative pressure state, the variable-rigidity puncture needle cylinder fixing module, namely the two-degree-of-freedom posture fixing module, is designed and manufactured, the puncture needle can be fixed at any posture, and the design is simple and compact.

The invention provides a four-degree-of-freedom passive pose fixing function and a two-degree-of-freedom active needle inserting function for the puncture needle, and can provide any pose fixing function and quantitative needle inserting and rotating operation functions for the puncture needle.

Description of the drawings:

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

FIG. 2 is a two-degree-of-freedom planar positioning module of the present invention;

FIG. 3 is a two-degree-of-freedom pneumatic attitude adjustment module of the present invention;

FIG. 4 is a two-degree-of-freedom hand-insertion module according to the present invention;

FIG. 5 is a detail view of the component 4;

FIG. 6 is a detail view of the part 5;

figure 7 part 4 locking bar detail view.

1-base, 2-adapter, 3-carbon fiber tube A, 4-locking strip, 5-female slide block, 6-air guide tube, 7-needle base female slide block, 8-locking air bag base, 9-lower fixing base of needle inserting module, 10-locking air bag, 11-carbon fiber tube B, 12-needle inserting slide block, 13-boss gear, 14-screw rod, 15-gear limiting piece, 16-biopsy needle, 17-upper fixing base of needle inserting module, 18-coupler, 19-needle inserting sleeve, 20-ball hinge, 21-pneumatic muscle, 22-tensile rope, 23-sub locking slide block, 24-air bag locking particle, 25-long gear column and 26-air inlet tube.

Detailed Description

As shown in the overall assembly drawing of fig. 1, the robot splits a six-degree-of-freedom robot into three independent working modules through a modular design, and mainly comprises a two-degree-of-freedom plane positioning module, a two-degree-of-freedom attitude fixing module and a two-degree-of-freedom rotary needle inserting module; the two-degree-of-freedom posture fixing module is installed on the two-degree-of-freedom plane positioning module, the two-degree-of-freedom rotary needle feeding module is installed on the two-degree-of-freedom posture fixing module, and the biopsy needle 16 is installed on the two-degree-of-freedom rotary needle feeding module. The two-degree-of-freedom posture fixing module is driven to horizontally move through the two-degree-of-freedom plane positioning module, the two-degree-of-freedom rotary needle inserting module is driven to incline along the needle inserting direction through the two-degree-of-freedom posture fixing module, and the biopsy needle 16 is driven to vertically lift and rotate through the two-degree-of-freedom rotary needle inserting module.

Specifically, the two-degree-of-freedom plane positioning module comprises a base 1, a plane positioning mechanism and a posture fixing mechanism; the two bases 1 are oppositely arranged in parallel at intervals, an adapter 2 is arranged at each end of each base 1, a plane positioning mechanism is arranged between each two ends of each base 1, and each plane positioning mechanism comprises a carbon fiber tube 3, a locking strip 4 and a female sliding block 5; the two carbon fiber tubes 3 penetrate through the female slider 5 in parallel and relatively at intervals and then are fixedly connected to one ends of the two bases 1 through the adaptor 2, the two locking strips 4 also penetrate through the female slider 5 in parallel and relatively at intervals and then are fixedly connected to one ends of the two bases 1 through the adaptor 2, and the two locking strips 4 are located below the carbon fiber tubes 3 and are respectively placed in parallel and relatively at intervals with the two carbon fiber tubes 3; still install one and plane positioning mechanism structure basically the same gesture fixed establishment between two plane positioning mechanism's female slider 5, female slider 5 in the gesture fixed establishment is as the female slider 7 of needle file, and carbon fiber tube 3 and locking strip 4 in the gesture fixed establishment all fixed connection to two female sliders 5, and wherein, base 1 provides the support through adaptor 2 for carbon fiber tube 3 and locking strip 4 and fixes.

As shown in fig. 2 and 5, the two-degree-of-freedom planar positioning module and the needle seat female slider 7 are hollow in the female slider 5 and the needle seat female slider 7, and in the respective interiors thereof, an air duct 6, a pneumatic muscle 21, a tension rope 22 and two sub-locking sliders 23 are horizontally arranged in a direction perpendicular to the sliding direction of the female slider 5 and the needle seat female slider 7 respectively; the pneumatic muscle 21 and the tension rope 22 are positioned between the two sub-locking sliding blocks 23, and the air duct 6 is arranged on the pneumatic muscle 21; after the air duct 6 inflates the pneumatic muscle 21, the pneumatic muscle 21 begins to expand to push the sub-locking sliding blocks 23 to move in the main sliding block 5 or the needle seat main sliding block 7 to the two sides until the sawtooth surfaces arranged on the outer sides of the locking sliding blocks 23 coincide with the sawtooth surfaces arranged on the inner sides of the locking strips 4 to form structural limit, the main sliding block 5 or the needle seat main sliding block 7 is fixed at the current position, and meanwhile, the tension rope 22 is tensioned; when the pneumatic muscle 21 does not work, the tension rope 22 tensions the sub-locking sliding blocks 23 on the two sides inwards, the sawtooth surfaces on the outer sides of the sub-locking sliding blocks 23 are separated from the sawtooth surfaces on the inner sides of the locking strips 4, and the structure limiting of the female sliding block 5 or the female sliding block 7 of the needle base is released. The pneumatic muscle 21 drives the sub-locking slide block 23 to match with the sawtooth surface to complete the switching of the sliding/locking state of the main slide block 5 and the needle base main slide block 7 on the guide rail, thereby completing the plane positioning.

The two female sliders 5 and the one needle base female slider 7 both take the carbon fiber tube 3 as a guide rail and freely slide along the carbon fiber tube 3; the female slider 5 and the needle seat female slider 7 are in sliding contact with the upper and lower surfaces of the locking strip 4 so as to freely slide along the locking strip 4 without contacting with the inner side serrated surface of the locking strip 4, and the part view of the locking strip 4 is shown in fig. 7. In addition, the posture fixing mechanism also comprises a spherical hinge 20, and the spherical hinge 20 is sleeved at the central position inside the needle seat female slide block 7 and is movably connected with the needle seat female slide block 7.

As shown in fig. 3, the two-degree-of-freedom pneumatic posture adjustment module comprises a locking airbag base 8, a locking airbag 10, a puncture needle sleeve 19 and airbag locking particles 24; the puncture needle sleeve 19 sequentially penetrates through the locking air bag 10, the locking air bag base 8 and the central through hole of the needle base female slider 7 from top to bottom and is fixedly arranged on a spherical hinge 20 arranged in the needle base female slider 7; the locking air bag base 8 is fixedly arranged at the upper part of the needle seat female sliding block 7, the locking air bag 10 is fixedly arranged on the air bag base 8, the needle seat female sliding block 7 is a spherical hinge 20 and provides an installation fulcrum for the locking air bag base 8, an air inlet pipe 26 is arranged on the side surface of the locking air bag 10, and a plurality of air bag locking particles 24 are arranged in the locking air bag 10, wherein the air bag locking particles 24 are round small balls and can freely flow in the air bag, and the locking air bag 10 is connected with an external vacuum pump through the air inlet pipe 26; when the interior of the locking air bag 10 is vacuumized, the locking air bag 10 contracts and extrudes the air bag locking particles 24, the air bag locking particles 24 and the locking air bag 10 form a fixed body together in the current posture after the fluidity disappears, and the puncture needle sleeve 19 on the spherical hinge 20 is locked by the fixed body in the current posture, so that two corresponding degrees of freedom of the spherical hinge 20, namely the degrees of freedom of rotation around the x axis and the y axis, are limited.

As shown in fig. 4, the two-degree-of-freedom rotational needle insertion module includes a needle insertion module lower fixing base 9, a carbon fiber tube B11, a needle insertion slider 12, a boss gear 13, a screw 14, a gear limit piece 15, a biopsy needle 16, a needle insertion module upper limit base 17, a coupling 18 and a long gear column 25; the upper limit seat 17 of the needle inserting module is positioned right above the lower fixed seat 9 of the needle inserting module, wherein the lower fixed seat 9 of the needle inserting module is connected with the upper limit seat 17 of the needle inserting module through a vertical carbon fiber tube B11, the screw 14 and the long gear column 25 are vertically arranged between the lower fixed seat 9 of the needle inserting module and the upper limit seat 17 of the needle inserting module in parallel with the carbon fiber tube B11, and the upper ends of the screw 14 and the long gear column 25 penetrate out of the upper limit seat 17 of the needle inserting module and are connected with an external driving source through respective couplings 18;

a needle inserting slide block 12 is arranged between the upper limiting seat 17 of the needle inserting module and the lower fixing seat 9 of the needle inserting module, a boss gear 13 is hinged on the needle inserting slide block 12, a central through hole is formed in the needle inserting slide block 12, and a biopsy needle 16 sequentially penetrates through the central through hole of the needle inserting slide block 12 from bottom to top and then is fixedly sleeved on the through hole where the central axis of the boss gear 13 is located.

The two-degree-of-freedom rotary needle inserting module further comprises a gear limiting piece 15, the needle inserting slider 12 is provided with the gear limiting piece 15 used for protecting the boss gear 13, and the biopsy needle 16 movably penetrates through a through hole formed in the gear limiting piece 15 at the same time.

The needle inserting slider 12 and the screw 14 form a rotary pair through an internal thread arranged on the side face, the screw 14 rotates to drive the needle inserting slider 12 to perform linear motion along the axis direction of the screw 14, namely, to move along the z axis, the biopsy needle 16 sequentially passes through the gear limiting part 15, the boss gear 13 and the central through hole of the needle inserting slider 12 from top to bottom and then is fixedly sleeved on the central axis of the boss gear 13, the boss gear 13 is meshed and connected with the long gear column 25 to form a gear pair, the long gear column 25 drives the boss gear 13 to perform circumferential rotation through the gear pair, further, the biopsy needle 16 is driven to rotate around the axis of the long gear column 16, namely, to rotate along the z axis, and the part diagram of the long gear column 25 is shown in fig. 6. The biopsy needle 16 passes through the needle inserting module bracket and then continues to pass through the puncture needle sleeve 19, and finally reaches the target human body; the lower needle module holder 9 in the needle module holder is connected downwards to the locking airbag 10. The gear stopper 15 serves to maintain the relative position of the boss gear 13 and the needle insertion slider 12.

In specific implementation, the locking air bag 10 utilizes negative pressure contraction to limit the flowability of air bag locking particles 24 in the locking air bag 10 to realize variable stiffness rigidity transformation, and controls the puncture needle sleeve 19 to be fixed in any posture.

Wherein, the long gear column 25 cooperates with the boss gear 13 to control the biopsy needle 16 to rotate quantitatively at an angle; the screw 14 is matched with the needle inserting slider 12 to control the needle inserting length of the biopsy needle 16 so as to realize quantitative needle inserting. The ball hinge 20 is movably connected with the needle seat female slide block 7 in the needle seat female slide block 7 to form a revolute pair.

The two-degree-of-freedom rotary needle inserting module is externally connected with a ceramic machine and a wire driving mechanism through a coupler to realize machine driving or directly driven manually to realize man-machine switching. And the whole mechanism is made of non-metal materials and can be compatible with CT-MRI detection equipment.

Claims

1. A pneumatic rigidity-variable six-freedom CT-MRI needle puncture robot is characterized in that; mainly comprises a two-degree-of-freedom plane positioning module, a two-degree-of-freedom attitude fixing module and a two-degree-of-freedom rotary needle inserting module; the two-degree-of-freedom posture fixing module is arranged on the two-degree-of-freedom plane positioning module, the two-degree-of-freedom rotary needle feeding module is arranged on the two-degree-of-freedom posture fixing module, and the biopsy needle (16) is arranged on the two-degree-of-freedom rotary needle feeding module.

2. The pneumatic variable-stiffness six-degree-of-freedom CT-MRI needle puncture robot of claim 1, wherein: the two-degree-of-freedom plane positioning module comprises a base (1), a plane positioning mechanism and a posture fixing mechanism; the two bases (1) are oppositely arranged in parallel at intervals, the two ends of each base (1) are respectively provided with an adapter (2), a plane positioning mechanism is arranged between the two ends of each base (1), and each plane positioning mechanism comprises a carbon fiber tube (3), a locking strip (4) and a female sliding block (5); the two carbon fiber tubes (3) penetrate through the female sliding block (5) in parallel at intervals and are fixedly connected to one ends of the two bases (1) through the adaptor (2), the two locking strips (4) penetrate through the female sliding block (5) in parallel at intervals and are fixedly connected to one ends of the two bases (1) through the adaptor (2), and the two locking strips (4) are located below the carbon fiber tubes (3) and are respectively placed in parallel with the two carbon fiber tubes (3) at intervals; a posture fixing mechanism which has the same structure as the plane positioning mechanism basically is also arranged between the female sliding blocks (5) of the two plane positioning mechanisms, the female sliding block (5) in the posture fixing mechanism is used as a needle base female sliding block (7), and the carbon fiber tube (3) and the locking strip (4) in the posture fixing mechanism are both fixedly connected to the two female sliding blocks (5);

the female sliding block (5) and the needle seat female sliding block (7) are hollow, and in the respective interiors, an air duct (6), a pneumatic muscle (21), a tension rope (22) and two sub-locking sliding blocks (23) are horizontally arranged in a direction perpendicular to the sliding direction of the female sliding block (5) and the needle seat female sliding block (7); the pneumatic muscle (21) and the tension rope (22) are positioned between the two sub-locking sliding blocks (23), and the air duct (6) is installed on the pneumatic muscle (21); after the air duct (6) inflates the pneumatic muscle (21), the pneumatic muscle (21) begins to expand to push the sub-locking sliding blocks (23) to move inside the main sliding block (5) or the needle seat main sliding block (7) to two sides until the sawtooth surfaces arranged on the outer sides of the locking sliding blocks (23) are overlapped with the sawtooth surfaces arranged on the inner sides of the locking strips (4) to form structural limit, the main sliding block (5) or the needle seat main sliding block (7) is fixed at the current position, and meanwhile, the tension rope (22) is tensioned; when the pneumatic muscle (21) does not work, the tension rope (22) tensions the sub-locking sliding blocks (23) on the two sides inwards, the sawtooth surfaces on the outer sides of the sub-locking sliding blocks (23) are separated from the sawtooth surfaces on the inner sides of the locking strips (4), and the structure limiting of the main sliding block (5) or the needle seat main sliding block (7) is released.

3. The pneumatic variable-stiffness six-degree-of-freedom CT-MRI needle puncture robot of claim 2, wherein: the two female sliding blocks (5) and the needle seat female sliding block (7) both take the carbon fiber tube (3) as a guide rail and freely slide along the carbon fiber tube (3); the female slider (5) and the female slider (7) of the needle seat are in sliding contact with the upper surface and the lower surface of the locking strip (4) so as to freely slide along the locking strip (4) and are not in contact with the inner side sawtooth surface of the locking strip (4).

4. The pneumatic variable-stiffness six-degree-of-freedom CT-MRI needle puncture robot of claim 2, wherein: the posture fixing mechanism also comprises a spherical hinge (20), and the spherical hinge (20) is sleeved at the central position inside the needle seat female sliding block (7) and is movably connected with the needle seat female sliding block (7);

the two-degree-of-freedom posture fixing module comprises a locking air bag base (8), a locking air bag (10), a puncture needle sleeve (19) and air bag locking particles (24); the puncture needle sleeve (19) sequentially penetrates through the central through holes of the locking air bag (10), the locking air bag base (8) and the needle seat female sliding block (7) from top to bottom and then is fixedly installed on a spherical hinge (20) installed inside the needle seat female sliding block (7); locking gasbag base (8) fixed mounting is in female slider (7) upper portion of needle file, locking gasbag (10) fixed mounting is on gasbag base (8), locking gasbag (10) side is provided with intake pipe (26), and locking gasbag (10) inside is equipped with a plurality of gasbag locking particles (24), locking gasbag (10) link to each other with outside vacuum pump through intake pipe (26).

5. The pneumatic variable-stiffness six-degree-of-freedom CT-MRI needle puncture robot of claim 1, wherein: the two-degree-of-freedom rotary needle inserting module comprises a needle inserting module lower fixing seat (9), a carbon fiber tube B (11), a needle inserting slider (12), a boss gear (13), a screw (14), a gear limiting piece (15), a biopsy needle (16), a needle inserting module upper limiting seat (17), a coupler (18) and a long gear column (25); the upper limiting seat (17) of the needle inserting module is positioned right above the lower fixing seat (9) of the needle inserting module, the lower fixing seat (9) of the needle inserting module is connected with the upper limiting seat (17) of the needle inserting module through a vertical carbon fiber tube B (11), a screw rod (14) and a long gear column (25) are vertically arranged between the lower fixing seat (9) of the needle inserting module and the upper limiting seat (17) of the needle inserting module in parallel to the carbon fiber tube B (11), and the upper ends of the screw rod (14) and the long gear column (25) are connected with an external driving source through respective couplers (18) after penetrating out of the upper limiting seat (17) of the needle inserting module;

a needle inserting sliding block (12) is arranged between the needle inserting module upper limiting seat (17) and the needle inserting module lower fixing seat (9), a boss gear (13) is hinged to the needle inserting sliding block (12), a central through hole is formed in the needle inserting sliding block (12), and the biopsy needle (16) sequentially penetrates through the central through hole of the needle inserting sliding block (12) from bottom to top and then is fixedly sleeved on the through hole where the central axis of the boss gear (13) is located;

the two-degree-of-freedom rotary needle inserting module further comprises a gear limiting piece (15), a needle inserting sliding block (12) is provided with the gear limiting piece (15) used for protecting the boss gear (13), and a biopsy needle (16) simultaneously and movably penetrates through a through hole formed in the gear limiting piece (15);

the needle inserting slider (12) and the screw rod (14) form a rotating pair through internal threads arranged on the side face, the screw rod (14) rotates to drive the needle inserting slider (12) to do linear motion along the axis direction of the screw rod (14), the biopsy needle (16) sequentially penetrates through a gear limiting piece (15), a boss gear (13) and a central through hole of the needle inserting slider (12) from top to bottom and is fixedly sleeved on the central axis of the boss gear (13), the boss gear (13) and a long gear column (25) are meshed and connected to form a gear pair, the long gear column (25) drives the boss gear (13) to do circumferential rotation through the gear pair so as to drive the biopsy needle (16) to rotate around the axis of the biopsy needle pair, and the biopsy needle (16) penetrates through a needle inserting module support and then continues to penetrate through the puncture needle sleeve (19) to finally reach a target human body; and a lower needle inserting module fixing seat (9) in the needle inserting module bracket is downwards connected to a locking air bag (10).

6. The pneumatic variable-stiffness six-degree-of-freedom CT-MRI needle puncture robot of claim 4, wherein: the locking air bag (10) utilizes negative pressure contraction to limit the fluidity of air bag locking particles (24) in the locking air bag (10) and control the puncture needle sleeve (19) to be fixed at any posture.

7. The pneumatic variable-stiffness six-degree-of-freedom CT-MRI needle puncture robot of claim 5, wherein: the long gear column (25) is matched with the boss gear (13) to control the biopsy needle (16) to rotate quantitatively at an angle; the screw rod (14) is matched with the needle inserting slider (12) to control the needle inserting length of the biopsy needle (16) to realize quantitative needle inserting.

8. The pneumatic variable-stiffness six-degree-of-freedom CT-MRI needle puncture robot of claim 1, wherein: the whole mechanism is made of non-metal materials.

9. The pneumatic variable-stiffness six-degree-of-freedom CT-MRI needle puncture robot of claim 1, wherein: the two-degree-of-freedom rotary needle inserting module is externally connected with a ceramic machine and a wire driving mechanism through a coupler to realize machine driving or directly driven manually to realize man-machine switching.

10. The pneumatic variable-stiffness six-degree-of-freedom CT-MRI needle puncture robot of claim 4, wherein: the spherical hinge (20) is movably connected with the needle seat female sliding block (7) in the needle seat female sliding block (7) to form a revolute pair.