Macro-micro control method for puncture robot

Abstract

The invention provides a macro-micro control method for a puncture robot, and belongs to the technical field of mechanical drive control, target area coarse positioning is realized by four-degree-of-freedom macro drive, target spot fine positioning is realized by four-degree-of-freedom micro drive, and puncture operation is executed by a two-degree-of-freedom puncture module; according to the system, key technical requirements of a robot system on degree-of-freedom configuration, working space, instrument operation, positioning precision, driving layout and the like are analyzed; pneumatic driving, hydraulic driving and bionic soft body driving are integrated, and the device has the advantages of large working space, conformal design, high rigidity and efficient motion characteristics of macro driving, microminiaturization, high rigidity and accurate positioning of micro driving and ultralight miniaturization and long-stroke linear and rotary conveying capacity of bionic soft body driving in a nuclear magnetic environment; precise positioning of a submillimeter-level target spot is completed, and the peristaltic bionic soft body drives and executes precise long-stroke puncture operation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of mechanical driving control, and particularly relates to a macro-micro control method for a puncture robot. BACKGROUND

[0002] In a robot-assisted puncture operation, the end operation precision is required to be high. Directly using an overall full-freedom robot system for positioning puts higher requirements on mechanical manufacturing, sensing and driving control for a clinical operation with large space and multiple degrees of freedom. Therefore, by designing a puncture robot with a macro-micro driving configuration, the macro driving and the micro driving can be respectively positioned with full degrees of freedom, the macro driving covers the full working space, and the micro driving is carried on the end of the macro driving and covers the maximum error of the macro driving. The design takes into account both the large space adjustment capability and the local fine adjustment requirement of high precision. For example, a 4-degree-of-freedom (lacking rotation along the axis of the puncture needle and transportation of the puncture needle) macro driving and a 4-degree-of-freedom (lacking rotation along the axis of the puncture needle and transportation of the puncture needle) micro driving are combined. A puncture module can be carried on the end of the micro driving and executed after the micro driving completes accurate positioning.

[0003] Although brain nerve intervention surgery has been widely used in clinic, it still faces multiple challenges due to the need for sub-millimeter positioning accuracy. Traditional manual operation is cumbersome and lacks intraoperative in-situ image feedback. In-vivo error accumulation can reach 5 mm, which may lead to treatment failure or risk of cerebral hemorrhage. Intraoperative MRI can provide surgeons with in-situ image feedback of brain tissue during surgery and continuous in-vivo instrument state information, providing an important direction to solve the above problems; however, this method still relies on manual operation, and it is difficult for doctors to make precise adjustments in the narrow MRI cavity (typical diameter of 60 cm). Patients often need to repeatedly enter and exit the MRI cavity, the operation efficiency is low, and the doctor's learning curve is long. In order to solve the above problems, using robot technology to realize intraoperative precise and stable brain nerve intervention is a practical solution. Although significant progress has been made in magnetic resonance compatible brain nerve intervention robot technology, existing systems still cannot meet the clinical needs of full automation, large range, and sub-millimeter in-vivo positioning. The root cause of the system precision bottleneck is mainly reflected in the following aspects: first, brain stereotactic positioning needs to meet the high stiffness driving demand of four degrees of freedom (excluding axial rotation and puncture freedom), and a driving mechanism is needed to achieve fast and stable stereotactic positioning within the limited magnet aperture; second, the limited operating area and large workspace of the brain form an inherent contradictory constraint for high-precision brain deep precise control. Third, the puncture mechanism design needs to integrate rotation-translation composite motion (stroke ≥5 cm) and high-precision target control in a compact space. The breakthrough of the above technical bottlenecks needs to be achieved in a strong magnetic field (3T) and a strong radio frequency environment, while the high sensitivity characteristics of magnetic resonance imaging must be considered. These magnetic resonance compatible requirements pose multiple technical limitations on material selection, drive mode design, and sensor technology development.

[0004] Currently, the prior art also has the technical problem that it is difficult to achieve full automation, large-scale, sub-millimeter in vivo positioning of clinical needs. The first FDA-approved magnetic resonance compatible brain surgery robot SYMBIS / NeuroArm (IMRIS) adopts a double mechanical arm architecture, which can realize intraoperative real-time anatomical monitoring through a mobile MRI magnet, and has unique advantages in complex craniotomy surgery such as glioma resection. The NeuroBlate system (Monteris Medical) has two degrees of freedom and can complete closed-loop operation of laser interstitial thermotherapy (LITT) and drug delivery under magnetic resonance guidance, but still needs to rely on a stereotactic frame to achieve Mini-Bolt skull anchoring. Although there are many innovative achievements in driving, sensing, materials and MRI compatible instrument design: for example, the 8-degree-of-freedom piezoelectric driving robot system developed by Fischer's team can achieve an end positioning accuracy of 1.45±0.66mm by suppressing electromagnetic interference; the 3-degree-of-freedom pneumatic driving puncture robot proposed by Stoianovici combines a manual adjustment system, and the absolute accuracy under intraoperative magnetic resonance guidance is 1.55±0.81mm; the hydraulic frameless system developed by Kwok's team achieves positioning accuracies of 1.7mm and 2.2mm on a skull model and a human specimen, respectively, but no brain nerve intervention robot system has achieved sub-millimeter in vivo end positioning accuracy. SUMMARY

[0005] In view of the defects in the prior art, the purpose of the present application is to provide a macro-micro control method for a puncture robot.

[0006] The macro-micro control method for a puncture robot provided by the present application comprises:

[0007] The target area is coarsely positioned by a four-degree-of-freedom macro drive, the target point is finely positioned by a four-degree-of-freedom micro drive, and the puncture operation is performed by a two-degree-of-freedom puncture module;

[0008] The four-degree-of-freedom macro drive comprises: translational motion along the x-axis, lifting or lowering motion around the y-axis, and arc motion around the x-axis; arc rotation motion around the x-axis;

[0009] The four-degree-of-freedom micro drive is arranged at the end of the macro drive, and the four-degree-of-freedom micro drive comprises: motion of the upper plane along the x-axis, motion of the upper plane along the y-axis, motion of the lower plane along the x-axis, and motion of the lower plane along the y-axis;

[0010] The two-degree-of-freedom puncture module is embedded in the micro drive platform, and the two-degree-of-freedom puncture module comprises: puncture motion along the puncture needle axis and rotation motion around the puncture needle axis.

[0011] Preferably, a coordinate system is established, and the collected data is converted in the coordinate system; the control method comprises:

[0012] Step S1: obtaining an initial motion path;

[0013] Step S2: according to the initial motion path, a four-degree-of-freedom macro drive reaches a planned target nearby;

[0014] Step S3: acquiring an end position of the puncture module, and judging whether an error between the end position of the puncture module and a planned end position of the puncture module in the initial motion path satisfies a workspace motion range of a micro drive; if not, a four-degree-of-freedom macro drive motion is compensated in position until the workspace motion range of the micro drive is satisfied, and step S4 is entered; if yes, step S4 is entered;

[0015] Step S4: acquiring an end position of the puncture module, and a four-degree-of-freedom micro drive reaches a coordinate position planned in the initial motion path;

[0016] Step S5: the puncture module performs a puncture operation.

[0017] Preferably, the four-degree-of-freedom macro drive is a kind of step-by-step pneumatic macro drive, adopts a dual-step pneumatic macro drive, designs a four-degree-of-freedom stereotactic positioning mechanism to realize driving in multiple modes, and controls the rotation angle of the robot through an optical encoder in a closed loop;

[0018] The four-degree-of-freedom micro drive is a kind of master-slave hydraulic micro drive, which integrates four-degree-of-freedom micro drive and mechanism in a parallel configuration of upper and lower planes by a linear hydraulic drive;

[0019] The puncture module is a kind of bionic puncture needle drive, which realizes two-degree-of-freedom linear rotation operation by soft drive.

[0020] Preferably, the four-degree-of-freedom macro drive is designed based on the freedom degree of the classic Leksell stereotactic frame and combined with the spatial operation demand of the narrow cavity of magnetic resonance, improved into a four-degree-of-freedom step-by-step pneumatic macro drive module (MAM), and a two-degree-of-freedom RCM mechanism is reserved. In the Leksell, there is a boundary interference problem in the translation along the z-axis and the y-axis among the traditional Cartesian three-translation degrees of freedom. By introducing the fourth degree of freedom, i.e., the arc rotation motion around the x-axis and the arc motion around the x-axis rotation along the third degree of freedom, a compound motion chain is formed to replace the horizontal translation. The kinematic coupling of the translation motion along the x-axis by the first degree of freedom along the center axis of the hole and the lifting or lowering motion around the y-axis by the second degree of freedom is realized to replace the vertical translation.

[0021] Preferably, the four-degree-of-freedom micro drive is realized by integrating a linear hydraulic drive into a four-degree-of-freedom hydraulic micro drive module (MiAM) in a parallel configuration of upper and lower planes.

[0022] The hydraulic drivers are arranged orthogonally in the plane (x-y arrangement) to realize spatial posture adjustment; each hydraulic driver is connected with the orthogonally connected rods with height difference through an L-shaped slider, so that the two drivers can realize two-degree-of-freedom orthogonal motion in the same plane through the form of up-down staggering; two active connecting rods and two passive connecting rods form a cubic configuration, and brass bushings are arranged at the connecting positions to ensure lubrication and coaxiality; a universal joint is used for linkage design of the upper and lower planes, the upper universal joint is fixedly connected with the connecting rod, and the lower one is connected with the connecting rod through a cylindrical bushing to form a relatively slidable connection.

[0023] Preferably, the puncture module is a structure obtained by embedding a soft driver in the center of a micro-drive platform;

[0024] The soft driver serves as a puncture channel in the center;

[0025] The puncture module is closely matched with the micro-drive platform;

[0026] The MRI visualization sheath is coaxially arranged with the soft driver to realize axial guidance of the puncture needle, and chamfers are designed at the interface positions to realize guidance in the puncture pre-assembly process.

[0027] Preferably, before the macro-micro control method is executed, a coordinate system needs to be established, and the collected data needs to be converted in the coordinate system. Specifically, the collected data is converted in the coordinate system to ensure the consistency and accuracy of the information.[P0, R0] I and [P0, R0] R respectively represent the robot end position (P0) and the pose (R0) in the image coordinate system (I) and the robot coordinate system (R). The subscript symbols of P0 and R0 are as follows: 0 represents the planned position and pose, t represents the current position and pose, and d represents the difference between the current position and the planned position and the difference between the current pose and the planned pose; q mac , q mic , and q insert respectively represent the macro-drive mechanism position, the micro-drive mechanism position, and the puncture needle insertion control signal.

[0028] Preferably, the puncture robot is provided with a strategy module, which analyzes, solves and controls the specific actions required to be performed by each drive mechanism of the robot according to the input data:

[0029] In the step S1, the macro-drive mechanism receives [P0, R0] R according to the preoperative planning:

[0030] The step S3, the current puncture module end position and posture is obtained according to a navigation system (such as a magnetic resonance device, an optical camera, a posture sensor and the like), the end position and posture needs to be converted to the [P t , R t ] R , which is input into the strategy module to determine whether the error meets the workspace motion range of the micro drive, if not, the macro iteration process is entered, the end position and posture difference of the end is solved according to the end position and posture compensation algorithm of the macro drive mechanism, and the end position of the puncture module is gradually adjusted in the macro drive mechanism until the coarse positioning convergence condition meets the workspace motion range of the micro drive;

[0031] In the step S4, when the position and posture meets the workspace motion range requirement of the micro drive, the end position and posture of the puncture module is obtained again, then the micro drive part is entered, similar to the macro drive, the puncture module end position and posture error at this time is input into the iteration algorithm of the micro drive, at this time, the macro drive mechanism parameter q mac The approximate position and posture of the platform base of the positioning micro drive mechanism is determined, which is used to match the origin coordinate system of the puncture robot at this time, through cyclic iteration, until the robot meets the fine positioning convergence condition;

[0032] In the step S5, when the end positioning result of the puncture module meets the pose requirement set by the initial planning path, the puncture module starts the needle insertion operation; in the process, the image navigation real-time feedbacks the distance between the needle tip and the target point, and feeds back the distance to the linear conveying control module in the strategy module, until the depth meets the puncture setting requirement, the control iteration is stopped, the robot is locked, and the positioning operation is completed.

[0033] A parameter acquisition method for a macro-micro control method for a puncture robot provided by the application, comprising:

[0034] Step SD1: confirming the mechanism parameters of the macro drive according to actual needs, obtaining a DH parameter table and establishing a macro kinematics equation;

[0035] Step DS2: setting the mechanism error value;

[0036] Step SD3: obtaining the end pose of the set value by calculating the macro kinematics equation of step SD1, and substituting the error value of step SD2 to obtain the end pose containing the error;

[0037] Step SD4: establishing a micro drive kinematics equation according to a micro kinematics configuration;

[0038] Step SD5: combining the two end poses given in step SD3, calculating the mechanism parameters that need to be compensated by the micro drive, and recording the current mechanism motion value of the micro drive;

[0039] Step SD6: combined with the calculation method of step SD3 to step SD5, through cyclic iteration, traverse different errors and micro drive mechanism parameters under different macro drive poses, take the maximum error value, obtain the minimum value of the theoretical design of the micro drive mechanism parameters required;

[0040] Step SD7: further verify the micro drive parameters and macro drive errors obtained, set any one trajectory and target point, obtain the workspace of macro drive, the error range of macro drive, and the compensation range of micro drive.

[0041] Preferably, in the step SD1, define {o0} as the world coordinate system, and define the following four degrees of freedom of macro drive: translate d1 from {o0} to {o1} along the x-axis of {o0}, that is, the first degree of freedom movement of the robot: translation movement 1011 along the x-axis; rotate a2 from {o1} to {o2} around the y-axis of {o1}, that is, the second degree of freedom movement of the robot: lifting or lowering movement 1012 around the y-axis; rotate b3 from {o2} to {o3} around the x-axis of {o2}, that is, the third degree of freedom of the robot: arc arch movement 1013 around the x-axis; translate r arc from {o3} to {o4} along the z-axis of {o3}, r arc is the arc radius, which is a fixed parameter; rotate b4 from {o4} to {o5} around the x-axis of {o4}, that is, the fourth degree of freedom of the robot: arc rotation movement 1014 around the x-axis; the macro kinematics equation is established by the homogeneous transformation method, and the transformation matrix definition process is as follows:

[0042] Translation movement (1011) along the x-axis, translation d1: translation matrix along the x-axis of {o0}:

[0043]

[0044] Lifting or lowering movement (1012) around the y-axis, rotation a2: rotation matrix around the y-axis of {o1}:

[0045]

[0046] Arc arch movement (1013) around the x-axis, rotation b3: rotation matrix around the x-axis of {o2}:

[0047]

[0048] Translation r arc : fixed translation matrix along the z-axis of {o3}:

[0049]

[0050] Arc rotation around x-axis (1014), translation β4: rotation matrix around x-axis of {o4}:

[0051]

[0052] The end coordinate system {o5} of the macro is obtained by matrix multiplication of the homogeneous transformation matrix T0 of the world coordinate system {o0} relative to the world coordinate system {o0}: 5 :

[0053]

[0054] Substituting equations (0-1) to (0-5) gives:

[0055]

[0056] Since the robot needs to be closed-loop controlled according to the position and posture of the end during macro driving, a virtual translation d5 along the z-axis of {o5} is introduced as the fifth degree of freedom at the end point to simulate the puncture motion to reach the target point, and the virtual translation d5 is obtained as the fifth degree of freedom matrix:

[0057]

[0058] Further, the homogeneous transformation matrix of the virtual end coordinate system d6 of the macro driving relative to the world coordinate system {o0} is obtained:

[0059]

[0060] Substituting equation (0-8) gives:

[0061]

[0062] In the step SD2, according to the mechanism error and mechanical assembly error of the macro driving, the maximum value of the error is set, and the error value is directly related to the design method and processing method of each mechanism of the robot, and is obtained through testing; Generally, the error in both positive and negative directions and the mechanism error under different macro driving postures need to be considered;

[0063] In the step SD3, the Monte Carlo method is used to further calculate the macro kinematics equation containing the above error matrix, and N sets of values are randomly sampled within the motion range of each mechanism variable; The end position corresponding to each set of mechanism variables is calculated through the kinematics model. The sampling points are plotted as a 3D point cloud diagram; For each set of errors, the end pose of the set value and the end pose containing the error can be obtained, which is used for calculation of the micro driving part;

[0064] In the step SD4, the world coordinate system origin O mi is located between the upper and lower planes, Omi Homogeneous transformation matrix for driving the fourth degree of freedom Corresponding end point; upper plane motion point A (x1, y1, z1), wherein x1, y1 are the degrees of freedom of the upper plane along the X, Y directions, corresponding to the motion of the upper plane along the x axis 1021, the motion of the upper plane along the y axis 1022, and z1 is the fixed distance d of point A to the origin O mi up Lower plane motion point B (x2, y2, z2), wherein x2, y2 are the degrees of freedom of the lower plane along the X, Y directions, corresponding to the motion of the lower plane along the x axis 1023, the motion of the lower plane along the y axis 1024; -z2 is the fixed distance d of point B to the origin O mi down Translation from point A to target point P0 along AB by L5: the direction vector AB of AB is:

[0065] AB = [x2-x1, y2-y1, z2-z1] T (0-11)

[0066] Therefore, the unit direction vector n AB of AB is:

[0067]

[0068] The vector P0 of point P0 represents translation L5 along the direction of AB from point A:

[0069]

[0070] The RPY (ZYX) Euler angle is used to define the pose of straight line AB, wherein Roll (φ mi ) represents the rotation angle around the x axis, since there is no degree of freedom of rotation around the AB axis in the needle insertion direction, φ is assumed to be 0; Pitch (θ mi ) represents the rotation angle around the y axis, which is determined by the angle between AB and the z axis:

[0071]

[0072] Yaw (ψ mi ) represents the rotation angle around the z axis, which is determined by the projection direction of AB in the XY plane:

[0073]

[0074] Finally, the pose of point P0 can be expanded to a 6x1 vector:

[0075]

[0076] For inverse kinematics solution of micro-drive, according to the end navigation, the current pose is P​​t :

[0077] P t = [x p y p z p 0 θ mi，p ψ mi，p ] T (0-17)

[0078] where x p , y p , z p are the spatial coordinates of P t in the Cartesian coordinate system, the error offset of the two points A, B is defined as:

[0079]

[0080] where, is the projection length of the error offset on AB, by the definition of the pitch angle:

[0081]

[0082] Further derivation:

[0083]

[0084] From the expression (0-13) in forward kinematics:

[0085] z p = d up + L5cosθ mi，p (0-21)

[0086] Therefore:

[0087]

[0088] For the driving variables of the upper plane:

[0089]

[0090] Solving (0-18), (0-19), (0-20), (0-22) simultaneously:

[0091]

[0092] For the driving variables of the lower plane, solve (0-18) and (0-24) simultaneously:

[0093]

[0094] The final inverse solution expression of micro-drive:​

[0095]

[0096] Compared with the prior art, the present application has the following beneficial effects:

[0097] 1、The present application realizes sub-millimeter target point accurate positioning through four-degree-of-freedom macro drive for target area rough positioning and four-degree-of-freedom micro drive for target point accurate positioning;

[0098] 2、The present application has the advantages of good conformance, high rigidity and high-efficiency motion characteristics through pneumatic macro drive;

[0099] 3、The present application has the advantages of miniaturization, high rigidity and accurate positioning in the limited operation space at the end through hydraulic micro drive;

[0100] 4、The present application realizes super miniaturization and has the advantages of long-stroke linear rotation conveying capacity and good end load capacity through the bionic soft drive design of the puncture module;

[0101] 5、The present application can realize high-efficiency and accurate positioning operation through the introduction of the strategy module to calculate and control the macro-micro drive mechanism and the puncture module;

[0102] 6、The overall structure of the present application is suitable for strict micro-environment operation covering requirements such as clinical use of nuclear magnetic resonance. BRIEF DESCRIPTION OF DRAWINGS

[0103] Other features, objects and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments with reference to the following drawings:

[0104] Figure 1 The macro-micro control method flowchart for the puncture robot of the present application;

[0105] Figure 2 The robot architecture schematic diagram of the embodiment of the present application;

[0106] Figure 3 The correlation analysis diagram of each substructure of the embodiment of the present application;

[0107] Figure 4 The kinematics degree-of-freedom schematic diagram of the macro drive and micro drive of the present application;

[0108] Figure 5 The macro-micro compensation workspace schematic diagram of the present application;

[0109] Figure 6 The macro drive mechanism architecture and workspace schematic diagram of the present application;

[0110] Figure 7 The four-degree-of-freedom modeling schematic diagram of the micro drive of the present application.

[0111] Figure 8 Figure 1 is a flow chart showing a comparison between the embodiment of the present application and a conventional brain nerve intervention operation process.

[0112] Figure 9 Figure 2 is a diagram showing an experimental analysis of a simulation of a clinical nucleus positioning phantom according to the present application.

[0113] Figure 3 shows:

[0114] DETAILED DESCRIPTION

[0115] The present application will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present application, but do not limit the present application in any form. It should be noted that, for those skilled in the art, without departing from the concept of the present application, a number of changes and improvements can be made. These all belong to the protection scope of the present application.

[0116] As shown in Figures 1 to 7 the embodiment of the present application provides a macro-micro control method for a puncture robot, comprising:

[0117] The target area is coarsely positioned by a four-degree-of-freedom macro drive, the sub-millimeter target point is precisely positioned by a four-degree-of-freedom micro drive, and the puncture operation is performed by a two-degree-of-freedom puncture module;

[0118] The four-degree-of-freedom macro drive comprises: a translational motion 1011 along the x-axis, a lifting or lowering motion 1012 around the y-axis, an arc motion 1013 around the x-axis, and an arc rotation motion 1014 around the x-axis;

[0119] The four-degree-of-freedom micro drive is arranged at the end of the macro drive, and is a four-degree-of-freedom motion mechanism with an upper and lower plane, wherein the four-degree-of-freedom micro drive comprises: an upper plane motion 1021 along the x-axis, an upper plane motion 1022 along the y-axis, a lower plane motion 1023 along the x-axis, and a lower plane motion 1024 along the y-axis;

[0120] The two-degree-of-freedom puncture module is embedded in the micro drive platform, and comprises a puncture motion along the puncture needle axis and a rotation motion around the puncture needle axis.

[0121] Further, before performing the control method, a coordinate system needs to be established, and the collected data needs to be converted in the coordinate system; the control method comprises:

[0122] Step S1: obtaining an initial motion path;

[0123] Step S2: according to the initial motion path, the four-degree-of-freedom macro drive reaches the vicinity of the planned target;

[0124] Step S3: Obtain the end position of the puncture module, and determine whether the error between the end position of the puncture module and the planned end position of the puncture module in the initial motion path meets the workspace motion range of the micro drive; if not, the four-degree-of-freedom macro drive performs position compensation until the workspace motion range of the micro drive is met, and step S4 is entered; if yes, step S4 is entered.

[0125] Step S4: Obtain the end position of the puncture module, and the four-degree-of-freedom micro drive reaches the coordinate position planned in the initial motion path.

[0126] Step S5: The puncture module performs puncture operation.

[0127] Further, as shown in Figures 2 to 3 , the four-degree-of-freedom macro drive is a kind of step-by-step pneumatic macro drive, adopts a kind of step-by-step pneumatic macro drive, designs four-degree-of-freedom stereotactic positioning mechanism to realize the driving of multiple modes: linear motion, rotary motion, arc motion and swing on arc, and the rotation angle of robot is closed loop controlled by optical encoder: the above driving mode is arranged in the operation space, since the step-by-step pneumatic drive has self-locking capability, therefore, the design can meet the clinical demand. The four-degree-of-freedom micro drive is a kind of master-slave hydraulic micro drive, which integrates four-degree-of-freedom micro drive mechanism by linear hydraulic drive in upper and lower double planes, and the parallel mechanism can better realize attitude adjustment, compensate the end error of step-by-step pneumatic drive, and the driving mode of hydraulic drive is more easily miniaturized, which can be further deployed at the end of macro drive without introducing too large load, to meet the clinical demand. The puncture module is a kind of bionic puncture needle drive, which realizes two-degree-of-freedom linear rotation operation by soft drive, meets the freedom requirement of brain nerve intervention, and the compact and light structure can be deployed in limited space, and the driving resolution is higher, which has reliable performance for deep puncture; further design MRI guided stereotactic sheath, the travel path of puncture needle is coaxial with the center line of sheath, to realize accurate positioning in the same MRI scanning state.

[0128] Next, more specific embodiments will be described in more detail:

[0129] Embodiment 1

[0130] In this embodiment, as shown in Figure 3 b, the four-degree-of-freedom macro drive is designed based on the freedom of the classic Leksell stereotactic frame and combined with the space operation requirement of the narrow cavity of magnetic resonance, and improved as Figure 3a four-degree-of-freedom stepping pneumatic macro drive module (MAM) shown in FIG. b; the original Leksell frame contains three translational degrees of freedom (x, y, z axes) in the Cartesian coordinate system and two degrees of freedom of motion that can realize remote center motion (RCM); this embodiment retains the two degrees of freedom of RCM mechanism, the motion space of which matches the geometry of the human brain, and the implementation thereof is realized by Figure 3 the second degree of freedom of b, i.e., the lifting or lowering motion 1012 rotating around the y-axis, and the third degree of freedom, i.e., the arc arch motion 1013 rotating around the x-axis, constitute; due to the spatial constraints of the MRI cavity, there is a boundary interference problem in the traditional Cartesian three translational degrees of freedom in Leksell along the z-axis and y-axis translation. By introducing the fourth degree of freedom, i.e., the arc rotation motion 1014 rotating around the x-axis, a composite motion chain is formed with the third degree of freedom, replacing the transverse (y-axis) translation. The up-down translation is realized by the kinematic coupling of the first degree of freedom, i.e., the translational motion 1011 moving along the x-axis, and the second degree of freedom, replacing the longitudinal (z-axis) translation.

[0131] The first degree of freedom translational motion and the second degree of freedom lifting motion are driven by rotary pneumatic motors and use polyether ether ketone (PEEK) leadscrews (pitch 4mm) to realize high-resolution translation (4 / 36=0.11mm / step) and stable lifting (≈0.1° / step) compatible with magnetic resonance; to minimize the volume of the drive module, the translational motion uses needle bearings for guidance, and the two sets of leadscrews are arranged in parallel, so that the overall height of the first and second degree of freedom drive structures is only 48.5mm; the third degree of freedom drive integrates the output gear into the arc structure, uses the conformal pneumatic drive proposed in the second chapter, designs the motion module into a structure that matches the curvature of the arc, and designs the drive pistons to be symmetrically distributed on both sides of the arc structure, realizing stepping motion (0.5° / step) along the 200mm radius arc trajectory; similarly, a smaller output gear is installed on the arc structure to realize the arc rotation motion (0.5° / step) around the x-axis, with a rotation radius of 70mm; the RCM point realized by the second and third degrees of freedom on the mechanism is designed to coincide with the center of the MRI cavity, and the positioning of the fixed head frame is matched to ensure that the subject's brain is closest to the MRI imaging center, thereby obtaining the best imaging quality; in a feasible implementation, the macro drive of the four degrees of freedom can be realized by the macro structure provided in the patent with application number CN202311213750.2.

[0132] In this embodiment, as Figure 3As shown in Figure c, the four-degree-of-freedom micro-drive is achieved by integrating linear hydraulic actuators into a four-degree-of-freedom hydraulic micro-drive module (MiAM) in a parallel configuration of upper and lower dual planes. The hydraulic actuators are orthogonally arranged (xy arrangement) in their respective planes to achieve precise adjustment of spatial attitude. Each hydraulic actuator is connected to an orthogonal link with a height difference via an L-shaped slider, so two actuators can achieve two-degree-of-freedom orthogonal motion in the same plane by staggering their upper and lower parts. Two active links and two passive links form a cubic configuration, and brass bushings are provided at the connection points to ensure lubrication and coaxiality. During the swing motion adjustment process, the length of the connecting rod between the two planes will change, so a universal joint is used for linkage design of the upper and lower planes. The upper universal joint is designed to be fixed to the link, and the lower part is connected to the link via a cylindrical bushing to form a relatively sliding connection. Based on this design, the degrees of freedom of the MiAM system can be further calculated as follows:

[0133]

[0134] In this embodiment, as Figure 3 As shown in c, the puncture module can specifically be a software driver ( Figure 3 c-ii) Embedding the micro-platform center to obtain as follows Figure 2 The structure shown in c-iii; the software driver serves as the central puncture channel, and the puncture module is tightly integrated with the micro-drive platform; more specifically, as... Figure 3 As shown in c-iv, an adaptive assembly method is used to set a negative pressure input, causing the soft actuator to shrink in volume. After embedding it into the central hole of the micro-platform, the pressure is restored to normal. Due to its surface friction and the stress after expansion, a tight assembly between the soft actuator and the micro-platform can be achieved. The MRI imaging guide sheath is designed to be coaxially arranged with the actuator to achieve axial guidance of the puncture needle, and a chamfer is designed at the interface to guide the puncture pre-assembly process. In a feasible embodiment, the four-degree-of-freedom micro-actuator can be realized by the microstructure provided by the patent application number 2024107835725, and the puncture operation can be realized by the puncture structure designed by the patent application number 202510118086.6.

[0135] Before implementing the macro-micro control method, a coordinate system needs to be established, and the collected data needs to be transformed to ensure the consistency and accuracy of the information. [P0, R0] I With [P0, R0] R q represents the robot's end-effector position (P0) and pose (R0) in the image coordinate system (I) and robot coordinate system (R), respectively. The subscripts for P0 and R0 are: 0 represents the planned position and pose, t represents the current position and pose, and d represents the difference between the current position and the planned position and pose.mac , q mic , q insert respectively represent macro drive mechanism position, micro drive mechanism position, puncture needle needle control signal;

[0136] Further, the puncture robot executing the embodiment is provided with a strategy module, which analyzes, solves and controls the specific actions required to be performed by each drive mechanism of the robot according to input data:

[0137] In the step S1, the macro drive mechanism receives [P0, R0] according to the preoperative planning R ;

[0138] In the step S3, the current puncture module end position and attitude are obtained according to the navigation system (such as a magnetic resonance device, an optical camera, a posture sensor, etc.), which needs to be converted to [P t , R t ] R , which is input into the strategy module to determine whether the error meets the workspace motion range of the micro drive. Generally, the error convergence condition can be designed according to the workspace motion range of the micro drive, such as: position error ≥ 1 mm, angle error ≥ 1°, then enter the macro iteration process, according to the end position and attitude compensation algorithm of the macro drive mechanism, such as the Jacobian iteration method, the change of the macro drive mechanism is solved according to the difference of the end position and attitude, and the end position of the puncture module is further adjusted step by step in the macro drive mechanism until the coarse positioning convergence condition is met, such as: position error < 1 mm, angle error < 1°;

[0139] In the step S4, when the position and attitude meet the workspace motion range requirement of the micro drive, the end position and attitude of the puncture module are obtained again, then the micro drive part is entered, similar to the macro drive, the puncture module end position and attitude error at this time is input into the iteration algorithm of the micro drive, and it is noted that the macro drive mechanism parameter q mac at the last moment of step S3 needs to be combined. The approximate position and attitude of the platform base of the micro drive mechanism are determined, which is used to match the origin coordinate system of the puncture robot at this time, through cyclic iteration, until the robot meets the fine positioning convergence condition, such as: position error < 0.1 mm, angle error < 0.1°;

[0140] In the step S5, when the end positioning result of the puncture module meets the position and attitude requirement set by the initial planning path, the puncture module starts the needle operation; in this process, the image navigation feedbacks the distance between the needle tip and the target point in real time, and feeds back the distance to the linear conveying control module in the strategy module, until the depth meets the requirement, such as: the end error of the puncture module < 0.1 mm, stop control iteration, lock the robot, and complete the positioning operation.

[0141] Embodiment 2

[0142] Further, in the implementation process of the fine adjustment of Embodiment 1, the main error sources of the macro drive in the embodiment include insufficient meshing of the master and slave gears during stepping motion (which can be obtained by experimental testing of the pneumatic motor), mechanical assembly error, and mechanism size calibration error; the mechanical assembly error and the mechanism size calibration error are negligible compared to the stepping error of the pneumatic drive, so the comprehensive cumulative error is limited within the range of a single pneumatic step, and based on the macro-micro kinematics model, the micro drive design parameters covering the macro drive error can be further established; specifically, the embodiment provides a more specific parameter acquisition method for the macro-micro control method of the puncture robot, comprising:

[0143] Step SD1: confirming the mechanism parameters of the macro drive according to actual needs, obtaining a DH parameter table and establishing a macro kinematics equation;

[0144] Step DS2: setting the mechanism error value; specifically: setting the mechanism error value according to the mechanism error of the macro drive and the mechanical assembly error;

[0145] Step SD3: calculating the end pose of the set value by the macro kinematics equation of step SD1, and substituting the error value of step S2 to obtain the end pose containing the error;

[0146] Step SD4: establishing a kinematics equation of the micro drive according to the micro kinematics configuration; more specifically, since the two sets of end poses given by the macro drive are based on the coordinate system origin of the macro drive mechanism, the inverse kinematics equation of the micro drive needs to be calculated based on the current macro drive pose;

[0147] Step SD5: combining the two end poses given in step SD3, calculating the mechanism parameters that need to be compensated by the micro drive, and recording the current mechanism motion value of the micro drive;

[0148] Step SD6: combining the calculation methods of steps SD3 to SD5, through cyclic iteration, traversing the micro drive mechanism parameters under different errors and different macro drive poses, taking the maximum value, and obtaining the theoretical design minimum value of the mechanism parameters required by the micro drive;

[0149] Step SD7: further verifying the micro drive parameters obtained and the error of the macro drive, setting an arbitrary trajectory and target point, obtaining the workspace of the macro drive, the error range of the macro drive, and the compensation range of the micro drive as shown in Figure 6 and Figure 7 Therefore, the micro drive mechanism parameters obtained through the algorithm of the embodiment can meet the design requirements of the macro-micro compensation of the robot.

[0150] More specifically, the step SD1 includes as shown in Figure 5 ​Figure 5 a is a schematic diagram of four-degree-of-freedom pneumatic macro drive coordinate system transformation relationship, Figure 5 b is the envelope relationship between the macro drive workspace and the standard human brain model); define {o0} as the world coordinate system, and define the following four degrees of freedom of the macro drive: translate d1 along the x-axis of {o0} to {o1}, which is the first degree of freedom of the robot: translation movement 1011 along the x-axis; rotate a2 around the y-axis of {o1} to {o2}, which is the second degree of freedom of the robot: lifting or lowering movement 1012 around the y-axis; rotate b3 around the x-axis of {o2} to {o3}, which is the third degree of freedom of the robot: arc arch movement 1013 around the x-axis; translate r arc to {o4} along the z-axis of {o3}, r arc is the arc radius, which is a fixed parameter; rotate b4 around the x-axis of {o4} to {o5}, which is the fourth degree of freedom of the robot: arc rotation movement 1014 around the x-axis; the macro kinematics equation is established by the homogeneous transformation method, and the transformation matrix definition process is as follows:

[0151] Translation movement 1011 along the x-axis, translation d1: translation matrix along the x-axis of {o0}:

[0152]

[0153] Lifting or lowering movement 1012 around the y-axis, rotation a2: rotation matrix around the y-axis of {o1}:

[0154]

[0155] Arc arch movement 1013 around the x-axis, rotation b3: rotation matrix around the x-axis of {o2}:

[0156]

[0157] Translation r arc : fixed translation matrix along the z-axis of {p3}:

[0158]

[0159] Arc rotation movement 1014 around the x-axis, translation b4: rotation matrix around the x-axis of {o4}:

[0160]

[0161] The homogeneous transformation matrix T0 5 of the end coordinate system {o5} of the macro relative to the world coordinate system {o0} is obtained by matrix multiplication:

[0162]

[0163] Substituting into equations (0-1) to (0-5), we get:

[0164]

[0165] Since the robot needs to perform closed-loop control based on the position and attitude of the end effector when performing macro-drive, a virtual translation d5 along the z-axis {p5} is introduced as the fifth degree of freedom at the end effector to simulate the puncture motion to reach the target point. The resulting matrix for the virtual translation d5 as the fifth degree of freedom is:

[0166]

[0167] Furthermore, the homogeneous transformation matrix of the macro-driven virtual end coordinate system d6 relative to the world coordinate system {p0} is obtained:

[0168]

[0169] Substituting into equation (0-8), we get:

[0170]

[0171] Furthermore, in step SD2, the maximum error value is set based on the macro-drive mechanism error and mechanical assembly error. The error value is directly related to the design method and processing method of each mechanism of the robot and is obtained through testing. It is usually necessary to consider the errors in both positive and negative directions as well as the mechanism errors under different macro-drive postures.

[0172] Furthermore, in step SD3, the Monte Carlo method is used to further calculate the macro-kinematic equations containing the above error matrices, traversing the range of mechanism variables, and randomly sampling N sets of values ​​for each mechanism variable within its motion range; the end-effector position corresponding to each set of mechanism variables is calculated through the kinematic model. The sampling points are plotted as a 3D point cloud map; for each set of errors, the end-effector pose with a set value and the end-effector pose containing the error can be obtained for calculation of the micro-drive part;

[0173] Further, in step SD4, as Figure 6 As shown, the world coordinate system origin O of the micro-platform is set. mi Located between the upper and lower planes, O mi To drive the homogeneous transformation matrix of the fourth degree of freedom The corresponding endpoint; the upper plane motion point A(x1, y1, z1), where x1 and y1 are the degrees of freedom of the upper plane along the X and Y directions, respectively, corresponding to the upper plane's motion along the x-axis 1021 and the upper plane's motion along the y-axis 1022, and z1 is the distance from point A to the origin O. mi The fixed distance d up; lower plane motion point B (x2, y2, z2), wherein x2, y2 are the degrees of freedom of the lower plane along the X and Y directions, corresponding to the movement of the lower plane along the x axis 1023, the movement of the lower plane along the y axis 1024; -z2 is the fixed distance d of point B to the origin O mi down ; translating from point A along AB by L5 to reach the target point P0; the direction vector AB of AB is:

[0174] AB = [x2-x1, y2-y1, z2-z1] T (0-11)

[0175] Therefore, the unit direction vector n AB of AB is:

[0176]

[0177] The vector P0 of point P0 represents translating L5 from point A along the direction of AB:

[0178]

[0179] The RPY (ZYX) Euler angle is used to define the pose of straight line AB, wherein Roll (φ mi ) represents the rotation angle around the x axis, and since there is no degree of freedom of rotation around the AB axis in the needle insertion direction, φ is assumed to be 0; Pitch (θ mi ) represents the rotation angle around the y axis, which is determined by the angle between AB and the z axis:

[0180]

[0181] Yaw (ψ mi ) represents the rotation angle around the z axis, which is determined by the projection direction of AB in the XY plane:

[0182]

[0183] Finally, the pose of point P0 can be expanded into a 6x1 vector:

[0184]

[0185] For the inverse kinematics solution of micro-drive, according to the end navigation, the current time pose is obtained as P t :

[0186] P t = [x p y p z p 0 θ mi，p ψ mi，p ] T (0-17)​

[0187] Where, x p y p , z p P t In Cartesian coordinates, the error offset between points A and B in the upper and lower planes is defined as:

[0188]

[0189] in, The projection length of this error offset onto AB is given by the definition of the pitch angle:

[0190]

[0191] Further derivation yields:

[0192]

[0193] From the expression (0-13) in forward kinematics, we can obtain:

[0194] z p =d up +L5cosθ mi，p (0-21)

[0195] therefore:

[0196]

[0197] For the driving variables of the upper plane:

[0198]

[0199] Solve the system of equations (0-18), (0-19), (0-20), and (0-22).

[0200]

[0201] For the driving variables of the lower plane, solving equations (0-18) and (0-24) simultaneously yields:

[0202]

[0203] Therefore, the final inverse expression for the micro-drive is:

[0204]

[0205] In a more preferred embodiment, the robotic system used to perform the method of embodiment 1 mainly comprises a mechanical hardware part to perform the surgery and a control hardware part to control the motion of the robot; both the mechanical part and the control part are made of MRI compatible materials, thus the overall MRI compatibility can be guaranteed; however, most of the components of the control part are still MRI incompatible, if all the control end is placed outside the MRI room and the mechanical energy is transmitted to the robot end through waveguide, usually a distance of more than 8 m is needed, but the hydraulic pipeline and pneumatic pipeline will cause larger control delay and lower control stability after being extended, therefore, shortening the control link as much as possible (<3 m) can greatly improve the overall control performance; a modular design is adopted to arrange each functional module at different positions of the overall structure. The driving system based on the hierarchical control architecture adopts a four-level modular design, the top layer (the first layer) of the system is the central control layer of the robot, which is responsible for communicating with the external MRI navigation software, calculating the control parameters of the robot, and sending instructions to the specific execution layer to realize macro driving, micro driving and puncture motion. The second layer configures multiple pneumatic driving circuits, and the stepping motion of multiple pneumatic motors is realized through high-speed electromagnetic valves (MHP2-MSlH-52-M5, Festo). The third layer adopts a pressure controller (MK3+, Elveflow) for precise control; the fourth layer arranges four hydraulic driving modules to drive the motion of four micro driving hydraulic cylinders. A rotary motor (Dynamixel-MR106, ROBOTIS) is used to drive a lead screw (4 mm lead) to push the main cylinder to realize micron-level main end driving. The hydraulic pipeline is uniformly arranged at the bottom layer and is fully isolated from the possible liquid leakage position. The communication between the trolley and the external navigation software adopts optical fiber transmission. The shell is made of shielded aluminum alloy material, which fully wraps the whole trolley to ensure the shielding function of the radio frequency signal. The magnetic force test of the system in the 3T MRI environment ensures that the trolley can work outside the 40 mT magnetic field line without magnetic force interference.

[0206] As shown in Figure 8 , for the comparison between the brain nerve intervention operation process of the embodiment of the application and the traditional brain nerve intervention operation process, Figure 8 a shows the traditional process and its main error sources, Figure 8 b is the brain nerve intervention operation process corresponding to the embodiment of the application; as shown in Figure 9 , the simulation of the clinical nucleus positioning phantom experiment results of the embodiment of the application, Figure 9 a is a schematic of the overall phantom experiment scene, Figure 9 b is the MRI-guided guide sheath alignment process under the first rough positioning iteration, Figure 9 c is the MRI-guided guide sheath alignment process under the fifth fine positioning, Figure 9 d is the global MRI image of the robot intervention process, Figure 9 e is the local MRI image of the robot intervention process, Figure 9f represents the pose error curve that is continuously adjusted during the positioning process; Figure 9 g represents the curve showing the change in distance between the needle tip and the target point during the puncture procedure. Figure 9 h represents the mean and standard deviation of the seven phantom positioning experiments.

[0207] This invention utilizes the precise intraoperative positioning capabilities of robots to confirm brain drift and perform secondary calibration via a second MRI scan after craniotomy. Based on preoperative 3D MRI scans, the target point is selected and the puncture path is planned. Under MRI navigation, the robot achieves precise alignment of the guide sheath with the planned path through macro- and micro-drives. The changes in end-effector pose adjustment observed in the MRI images are as follows: Figure 9 As shown in b and c, the robot's macro-micro iterative process is as follows: Figure 9 As shown in f; subsequently, the puncture needle is installed, and the bionic soft actuator completes the puncture operation under MRI guidance. The change in the distance between the needle tip and the target point as shown in the magnetic resonance image is as follows. Figure 9 As shown in d and e, the robot's bionic soft-driven puncture process is as follows: Figure 9 As shown in g; postoperative MRI scans obtained absolute positioning accuracy by measuring the radial distance between pixels between the needle tip and the target point. Seven independent experiments showed that the radial error was less than 1 mm (0.39 ± 0.12 mm), verifying that the system has sub-millimeter-level absolute positioning accuracy. Figure 9 As shown in h.

[0208] In summary, this invention provides a macro-micro control method and parameter acquisition method for a puncture robot, applicable to precise positioning operations of puncture or interventional robots. For robots with a combination of macro and micro drives, the four-degree-of-freedom macro drive achieves coarse target area positioning, the four-degree-of-freedom micro drive achieves sub-millimeter-level precise target positioning, and the two-degree-of-freedom puncture module performs the puncture operation. This invention systematically analyzes the key technical requirements of the robot system in terms of degree-of-freedom configuration, workspace, instrument operation, positioning accuracy, and drive layout; it integrates pneumatic drive, hydraulic drive, and biomimetic soft drive, combining the advantages of macro drive (large workspace, conformal design, high rigidity, and efficient motion characteristics), micro drive (miniaturization, high rigidity, and precise positioning), and biomimetic soft drive (ultra-lightweight and long-stroke linear / rotary transport capability) in a nuclear magnetic resonance environment; achieving sub-millimeter-level precise target positioning, and the peristaltic biomimetic soft drive performs precise long-stroke puncture operations.

[0209] Those skilled in the art know that, in addition to implementing the system provided by the present application and each device, module and unit thereof in the form of pure computer readable program code, the system provided by the present application and each device, module and unit thereof can also be implemented in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers and embedded microcontrollers, etc. by logically programming the method steps to achieve the same functions. Therefore, the system provided by the present application and each device, module and unit thereof can be considered as a hardware component, and the devices, modules and units included therein for achieving various functions can also be considered as structures within the hardware component; the devices, modules and units for achieving various functions can also be considered as both software modules for implementing methods and structures within hardware components.

[0210] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0211] The specific embodiments of the present application are described above. It should be understood that the present application is not limited to the specific embodiments described above, and various changes or modifications can be made by those skilled in the art within the scope of the claims, which do not affect the essential content of the present application. The embodiments of the present application and the features in the embodiments can be arbitrarily combined with each other without conflict, provided that they do not conflict.

Claims

1. A macro-micro control method for a puncture robot, characterized by, The application relates to a macro-micro control method for a puncture robot. The four-degree-of-freedom macro drive is used for rough positioning of a target area, the four-degree-of-freedom micro drive is used for fine positioning of a target point, and the two-degree-of-freedom puncture module is used for puncture operation. The four-degree-of-freedom macro drive comprises translational movement (1011) along an x-axis, lifting or lowering movement (1012) around a y-axis, arc-shaped movement (1013) around the x-axis, and arc-up rotary movement (1014) around the x-axis. The four-degree-of-freedom micro drive is arranged at the end of the macro drive, and the four-degree-of-freedom micro drive comprises movement (1021) of an upper plane along the x-axis, movement (1022) of the upper plane along the y-axis, movement (1023) of a lower plane along the x-axis, and movement (1024) of the lower plane along the y-axis. The two-degree-of-freedom puncture module is embedded in the micro drive platform, and the two-degree-of-freedom puncture module comprises puncture movement along the axial direction of a puncture needle and rotary movement around the axial direction of the puncture needle.

2. The macro-micro control method for the puncture robot according to claim 1, wherein a coordinate system is established, and the collected data is converted in the coordinate system; and the control method comprises the following steps. Step S1: obtaining an initial motion path; Step S2: according to the initial motion path, the four-degree-of-freedom macro drive reaches a planned target nearby; Step S3: acquiring the end position of the puncture module, and judging whether the error between the end position of the puncture module and the planned end position of the puncture module in the initial motion path meets the working space motion range of the micro drive; if not, the four-degree-of-freedom macro drive is moved for position compensation until the working space motion range of the micro drive is met, and step S4 is entered; if yes, step S4 is entered; Step S4: acquiring the end position of the puncture module, and the four-degree-of-freedom micro drive reaches the coordinate position planned in the initial motion path; Step S5: the puncture module performs puncture operation.

3. The macro-micro control method for the puncture robot according to claim 1, wherein the four-degree-of-freedom macro drive is a kind of step-by-step pneumatic macro drive, a kind of dual step-by-step pneumatic macro drive is adopted, a four-degree-of-freedom three-dimensional positioning mechanism is designed to realize driving in multiple modes, and an optical encoder is used for closed-loop control of the rotation angle of the robot. The four-degree-of-freedom micro drive is a kind of master-slave hydraulic micro drive, a linear hydraulic drive is used to integrate four-degree-of-freedom micro drive and mechanism in a parallel configuration of upper and lower planes. The puncture module is a kind of bionic puncture needle drive, and a soft body drive is used to realize two-degree-of-freedom linear rotary operation.

4. The macro-micro control method for the puncture robot according to claim 3, wherein ​ ​ The four-degree-of-freedom macro drive is designed based on the freedom degree of the classic Leksell stereotactic frame and combined with the spatial operation requirement of the narrow cavity of a magnetic resonance imaging (MRI) device, improved into a four-degree-of-freedom stepping pneumatic macro drive module (MAM), and retains a two-degree-of-freedom RCM mechanism, wherein the traditional Cartesian three-translational freedom degrees in the Leksell device have a boundary interference problem along the z-axis and y-axis translation; a fourth degree of freedom, i.e., an arc rotation motion (1014) around the x-axis, is introduced to form a composite motion chain with the arc motion (1013) around the x-axis along the third degree of freedom, to replace the lateral translation; the up-down translation is realized through the kinematic coupling of the first degree of freedom, i.e., the translation motion (1011) along the x-axis along the central axis of the hole, and the second degree of freedom, i.e., the lifting or lowering motion (1012) around the y-axis, to replace the longitudinal translation.

5. The macro-micro control method for a puncture robot according to claim 3, characterized in that, The four-degree-of-freedom micro drive is realized by integrating linear hydraulic drives in a parallel configuration in two planes to a four-degree-of-freedom hydraulic micro drive module (MiAM); The hydraulic drives are arranged orthogonally in the plane to realize spatial attitude adjustment; each hydraulic drive is connected to an orthogonal connecting rod with a height difference through an L-shaped slider, so that the two drives can realize two-degree-of-freedom orthogonal motion in the same plane through the staggered arrangement of the two drives; two active connecting rods and two passive connecting rods form a cubic configuration, and brass bushings are arranged at the connecting positions to ensure lubrication and coaxiality; a universal joint is used for the linkage design of the upper and lower planes, the upper universal joint is fixed to the connecting rod, and the lower universal joint is connected to the connecting rod through a cylindrical bushing to form a relatively slidable connection.

6. The macro-micro control method for a puncture robot according to claim 3, characterized in that, The puncture module is a structure obtained by embedding a soft driver into the center of the micro drive platform; The soft driver serves as the central puncture channel; The puncture module is closely matched with the micro drive platform; An MRI imaging guide sheath is coaxially arranged with the soft driver to realize axial guidance of the puncture needle, and a chamfer is designed at the interface position to realize guidance during the puncture pre-assembly process.

7. The macro-micro control method for a puncture robot according to claim 2, characterized in that, Before the macro-micro control method is executed, a coordinate system needs to be established, and the collected data needs to be converted in the coordinate system. Specifically, the collected data is converted in the coordinate system to ensure consistency and accuracy of information; [P0, R0] I and [P0, R0] R respectively represent the robot end position (P0) and pose (R0) in the image coordinate system (I) and the robot coordinate system (R); the subscript symbols of P0 and R0 are as follows: 0 represents a planned position and pose, t represents a current time position and pose, and d represents a difference between a current time position and pose and the planned position and pose; q mac , q mic , and q insert respectively represent a macro drive mechanism position, a micro drive mechanism position, and a puncture needle insertion control signal.

8. The macro-micro control method for a puncture robot according to claim 7, characterized in that, The puncture robot is provided with a strategy module to analyze, calculate and control the specific actions to be performed by each drive mechanism of the robot according to input data: In the step S1, the macro drive mechanism receives [P0, R0] according to the preoperative planning R ; In the step S3, the current end position and posture of the puncture module is obtained according to a navigation system (such as a magnetic resonance device, an optical camera, a posture sensor, etc.), which needs to be converted into the end position and posture [P t , R t ] R in the robot coordinate system (R) to determine whether the error meets the workspace motion range of the micro drive by inputting the same into the strategy module. If not, the macro iteration process is entered, the end position and posture compensation algorithm of the macro drive mechanism is used to solve the change of the macro drive mechanism according to the difference of the end position and posture, and the end position of the puncture module is further adjusted step by step in the macro drive mechanism until the coarse positioning convergence condition meets the workspace motion range of the micro drive. In the step S4, when the position and posture meets the workspace motion range requirement of the micro drive, the position and posture of the puncture module end is acquired again, and then the micro drive part is entered. Similar to the macro drive, the position and posture error of the puncture module end at this time is input into the iterative algorithm of the micro drive. At this time, the macro drive mechanism parameter q mac The approximate position and posture of the platform base of the micro drive mechanism is located, which is used to match the origin coordinate system of the puncture robot at this time. Through cyclic iteration, until the robot meets the fine positioning convergence condition. In step S5, when the end position of the puncture module meets the pose requirements of the initial planned path, the puncture module starts the needle insertion operation; during this process, the image navigation feedbacks the distance between the needle tip and the target point in real time, and feeds the distance back to the linear delivery control module in the strategy module, until the depth meets the puncture setting requirements, the control iteration is stopped, the robot is locked, and the positioning operation is completed.

9. A parameter acquisition method for a macro-micro control method of a puncture robot according to claim 1, characterized by, It includes: Step SD1: confirming the mechanism parameters of the macro drive according to actual needs, obtaining a DH parameter table and establishing a macro kinematics equation; Step DS2: setting the mechanism error value; Step SD3: the end pose of the set value is obtained by calculating the macro kinematics equation of step SD1, and the end pose containing the error is obtained by substituting the error value of step SD2; Step SD4: according to the micro kinematics configuration, the kinematics equation of the micro drive is established; Step SD5: combining the two given end poses in step SD3, the mechanism parameters required to be compensated by the micro drive are calculated, and the current mechanism motion values of the micro drive are recorded; Step SD6: combining the calculation methods of steps SD3 to SD5, through cyclic iteration, the micro drive mechanism parameters under different errors and different macro drive poses are traversed, the maximum error value is taken, and the theoretical design minimum value of the mechanism parameters required by the micro drive is obtained; Step SD7: further verify the micro drive parameters and the error of the macro drive, set any trajectory and target point, obtain the working space of the macro drive, the error range of the macro drive, and the compensation range of the micro drive.

10. The parameter acquisition method for the macro-micro control method of the puncture robot according to claim 9, wherein, In the step SD1, define {o0} as the world coordinate system, and define the macro drive of the following four degrees of freedom: translate d1 along the x-axis of {o0} to {o1}, that is, the first degree of freedom movement of the robot: translation movement along the x-axis 1011; rotate α2 around the y-axis of {o1} to {o2}, that is, the second degree of freedom movement of the robot: lifting or lowering movement around the y-axis 1012; rotate β3 around the x-axis of {o2} to {o3}, that is, the third degree of freedom of the robot: arc arch movement around the x-axis 1013; translate r arc to {o4} along the z-axis of {o3}, r arc is the arc arch radius, which is a fixed parameter; rotate β4 around the x-axis of {o4} to {o5}, that is, the fourth degree of freedom of the robot: arc rotation movement around the x-axis 1014; the homogeneous transformation method is used to establish the macro kinematics equation, and the transformation matrix definition process is as follows: Translation movement (1011) along the x-axis, translation d1: translation matrix along the x-axis of {o0}: Lifting or lowering movement (1012) around the y-axis, rotation a2: rotation matrix around the y-axis of {o1}: Arc arch movement (1013) around the x-axis, rotation b3: rotation matrix around the x-axis of {o2}: Translation r arc : Fixed translation matrix along z-axis of {o3}: Arc rotation movement (1014) around the x-axis, translation b4: rotation matrix around the x-axis of {o4}: The homogeneous transformation matrix of the end coordinate system {o5} of the macro relative to the world coordinate system {o0} is obtained by matrix multiplication Substituting equations (0-1) to (0-5) obtains: Since the robot needs to be closed-loop controlled according to the position and posture of the end during macro drive, a virtual translation d5 along the z-axis of {o5} is introduced at the end point as the fifth degree of freedom to simulate the puncture movement to reach the target point, and the virtual translation d5 as the fifth degree of freedom matrix is obtained: Further, the homogeneous transformation matrix of the virtual end coordinate system d6 of the macro drive relative to the world coordinate system {o0} is obtained: Substituting equation (0-8) obtains: In the step SD2, the maximum error value is set according to the mechanism error and mechanical assembly error of the macro drive, which is directly related to the design method and processing method of each mechanism of the robot and is obtained through testing; generally, the positive and negative errors and the mechanism errors under different macro drive postures need to be considered; In the step SD3, the Monte Carlo method is used to further calculate the macro kinematics equation containing the above error matrix, the mechanism variable range is traversed, N sets of values are randomly sampled in the motion range of each mechanism variable; the corresponding end position of each set of mechanism variables is calculated through the kinematics model; the sampling points are plotted as a 3D point cloud diagram; for each set of errors, the end pose of the set value and the end pose containing the error are obtained, which are used for the calculation of the micro drive part; The origin O of the world coordinate system of the micro-platform is set in the step SD4 mi Between the upper and lower planes, O mi The homogeneous transformation matrix for driving the fourth degree of freedom The corresponding end point: the upper plane motion point A (x1, y1, z1), wherein x1 and y1 are the degrees of freedom of the upper plane along the X and Y directions, corresponding to the upper plane motion along the x-axis 1021, the upper plane motion along the y-axis 1022, and z1 is the fixed distance d of point A to the origin O mi up The lower plane motion point B (x2, y2, z2), wherein x2 and y2 are the degrees of freedom of the lower plane along the X and Y directions, corresponding to the lower plane motion along the x-axis 1023, the lower plane motion along the y-axis 1024, and -z2 is the fixed distance d of point B to the origin O mi down Translating from the A point to the target point P0 along AB by L5; the AB direction vector AB is:​​ AB = [x2 - x1, y2 - y1, z2 - z1] T (0-11) Thus, the unit directional vector n of AB is AB n = (B - A) / |B - A| The vector P0 of point P0 represents the translation of L5 along the AB direction from point A: RPY (ZYX) Euler angles are used to define the pose of the straight line AB, where Roll (φ mi ) represents the rotation angle around the x-axis, and φ = 0 is assumed since there is no freedom of rotation around the AB axis in the needle insertion direction; Pitch (θ mi ) represents the rotation angle around the y-axis, and is determined by the angle between AB and the z-axis; Yaw (ψ mi ) represents the rotation angle around the z-axis, determined by the AB projection direction in the XY plane: Finally, the pose of point P0 can be expanded to a 6xl vector: For inverse kinematics solution of micro-drive, the current pose is obtained according to end navigation as P t : P t = [x p y p z p 0 θ mi，p ψ mi，p ] T (0-17) wherein x p , y p , z p respectively represent the spatial coordinates of P t in the Cartesian coordinate system, and the error offset of the two points A and B on the upper and lower planes is defined as: where is the projection of the error offset on AB, which, by definition of the pitch angle, is given by Further derivation obtains: From the expression (0-13) in the forward kinematics: z p = d up + L5 cos θ mi，p (0-21) Therefore: For the driving variables of the upper plane: Solving (0-18), (0-19), (0-20), (0-22) simultaneously gives: For the lower plane driving variables, solving (0-18) and (0-24) gives: Final inverse kinematics expression for micro-drive:

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