Flexible rod-driven miniature six-degree-of-freedom minimally invasive manipulator and use method therefor

Abstract

A flexible rod-driven miniature six-degree-of-freedom minimally invasive manipulator and a use method therefor. The manipulator comprises five feeding units. Four of the five feeding units form a driving part of a four-degree-of-freedom plane guiding and positioning module, and the remaining feeding unit serves as a fifth feeding unit for pushing and pulling an operation tool to operate in a Z-axis direction. A sixth rotating unit capable of achieving rotation of the operation tool in the Z-axis direction is mounted at an output end of the fifth feeding unit. An output end of the sixth rotating unit is connected, by means of a flexible transmission rod, to the operation tool penetrating through the four-degree-of-freedom plane guiding and positioning module. The operation tool can achieve translation in an X-axis direction and a Y-axis direction and bidirectional deflection around an X axis and a Y axis separately under the action of the four-degree-of-freedom plane guiding and positioning module. Provided is a simplified six-degree-of-freedom manipulator that is lightweight, has enough output force and precision, and can achieve tasks such as drilling, puncture, and medicine injection of a microsurgery.

Description

A flexible rod-driven miniature six-degree-of-freedom minimally invasive operating device and its use method Technical Field

[0001] The present invention belongs to the technical field of minimally invasive medical treatment, and in particular to a flexible rod-driven miniature six-degree-of-freedom minimally invasive operating device and a method for using the same. Background Art

[0002] Minimally invasive surgery is a surgical procedure that allows internal surgical operations to be performed through tiny surface incisions. Because the incisions are narrow and the internal operating space is invisible, barehanded minimally invasive surgery is difficult. Auxiliary instruments based on multi-degree-of-freedom operating devices such as surgical robots are of great value in minimally invasive surgery. Currently, mature multi-degree-of-freedom minimally invasive surgical operating devices are large and expensive. Miniaturized minimally invasive surgical operating devices have the advantages of small size, small footprint, ease of movement, and low material cost. They have great application potential in microsurgery, emergency rescue, scientific research and other fields.

[0003] At least six degrees of freedom are required to achieve arbitrary position and posture manipulation of a rigid body in 3D space. Existing six-degree-of-freedom operating devices mainly have two configurations: series and parallel. Among them, the parallel six-degree-of-freedom operating device has a more compact structure, but its motion space is usually smaller, and there is a problem of kinematic coupling between the drive devices. The series device realizes a multi-degree-of-freedom configuration by connecting the components of each degree of freedom in sequence, and its structure is relatively simple. However, due to its step-by-step series configuration, this requires the degrees of freedom at the base end to be able to withstand a larger load, and the error of the previous degree of freedom will also interfere with the subsequent degree of freedom. Especially in the miniaturized six-degree-of-freedom operator device, it is limited by factors such as the volume, weight, precision, and load of the microstructure and the drive device. The more degrees of freedom in series, the greater the structural complexity and error risk.

[0004] As mentioned above, the currently available miniaturized minimally invasive surgical operating devices still have certain deficiencies in terms of degree of freedom, load, volume, etc. A typical example is the origami-structured microsurgical manipulation device published by Harvard University, which has only three degrees of freedom and a load force of only 27 millinewtons, which is difficult to meet the actual surgical operation force requirements (H.Suzuki, and RJWood, "Origami-inspired miniature manipulator for teleoperated microsurgery," Nature Machine Intelligence, vol.2, no.8, Aug, 2020); the lightweight surgical manipulation device that can be fixed to the top of the skull published by the National University of Singapore has only four degrees of freedom. Although its end effector is small and can provide a large load force, it requires an external bulky cable drive mechanism, which greatly reduces its portability (C.Li, NKKKing, and H.Ren, "A Skull-Mounted Robot with a Compact and Lightweight Parallel Mechanism for Positioning in Minimally Invasive Neurosurgery," Annals of Biomedical Engineering, vol.46, no.10, pp.1465-1478, Oct, 2018).

[0005] How to optimize the structural configuration, how to ensure that it has sufficient load capacity and degree of freedom while ensuring miniaturization, and at the same time reduce the structural complexity as much as possible, are important issues that need to be urgently addressed in the field of miniaturized minimally invasive surgical machines. Summary of the Invention

[0006] The purpose of the present invention is to address the problems existing in the prior art and provide a miniature six-degree-of-freedom minimally invasive operation device driven by a flexible rod that can be used for minimally invasive operations such as drilling, puncture, and injection, and a method of use thereof; the miniature six-degree-of-freedom minimally invasive operation device simplifies the design of the six-degree-of-freedom motion structure through flexible rod drive while taking into account motion accuracy, load capacity, volume and cost, and provides a method of use for solving motion control problems.

[0007] The purpose of the present invention is to be solved by the following technical solutions:

[0008] A flexible rod-driven micro six-degree-of-freedom minimally invasive operating device, characterized in that: the device includes five feeding units, four of which constitute the driving part of a four-degree-of-freedom plane guiding and positioning module, and the remaining feeding unit serves as a fifth feeding unit for pushing and pulling an operating tool to run along the Z-axis direction; a sixth rotating unit capable of realizing rotation of the operating tool along the Z-axis direction is installed on the output end of the fifth feeding unit; the output end of the sixth rotating unit is connected to the operating tool that passes through the four-degree-of-freedom plane guiding and positioning module through a flexible transmission rod; the operating tool can realize translation along the X-axis direction and the Y-axis direction, as well as bidirectional deflection around the X-axis and the Y-axis respectively under the action of the four-degree-of-freedom plane guiding and positioning module; the fifth feeding unit, the sixth rotating unit, and the four-degree-of-freedom plane guiding and positioning module cooperate with each other to realize fine and controllable movement of the six degrees of freedom of the operating tool.

[0009] The fifth feed unit is installed on the housing of the four-degree-of-freedom plane guide positioning module through a screw-in bracket; the screw-in bracket is a rigid structure, one end of which can be rigidly connected to the base of the fifth feed unit and the other end can be rigidly connected to the base of the four-degree-of-freedom plane guide positioning module.

[0010] A slot module is configured on the output end of the fifth feeding unit, and the motor base of the sixth rotating unit can match the slot module. The sixth rotating unit, the flexible transmission rod, and the operating tool are combined to form a replaceable module that can be switched according to needs.

[0011] The sixth rotation unit includes a motor base, a rotating motor, a rotating reducer and a transmission rod connecting piece. A rotating motor (servo motor, such as a stepping motor) is installed on the motor base arranged into an embeddable structure (such as a dovetail groove structure), and a rotating reducer (such as a planetary reducer) is installed at the output end of the rotating motor. A transmission rod connecting piece connected to a flexible transmission rod is installed on the output end of the rotating reducer. When the rotating motor rotates, it can drive the transmission rod connecting piece to rotate.

[0012] The center line of one end of the flexible transmission rod fixed to the output end of the sixth rotation unit is coaxial with the rotation axis of the output end of the sixth rotation unit, the center line of the other end of the flexible transmission rod connected to the operating tool is also coaxial with the rotation axis of the operating tool, and the central axis of the operating tool is coaxial with the plane guide axis of the four-degree-of-freedom plane guide positioning module.

[0013] And due to the presence of the flexible transmission rod, the feed axis of the fifth feed unit, the rotation axis of the sixth rotation unit and the plane guide axis of the four-degree-of-freedom plane guide positioning module are not limited to parallel or coaxial axes, and no additional gears or belt connections are required. The flexible transmission rod can compensate for the errors among the three through its own deformation, and at the same time, it can also complete the transmission of torque and thrust in the deformed state; thereby, the structural design of the six-degree-of-freedom minimally invasive operating device can be simplified and the miniaturization of the minimally invasive surgical device can be achieved.

[0014] The flexible transmission rod is a slender rod with large deflection, which is made of memory alloy wire (nickel-titanium alloy) and can still transmit torque and thrust when it is bent to a certain extent.

[0015] The operating tools are rigid, slender tools that can rotate and feed and are required for minimally invasive microsurgery, typically micro drills, puncture needles, injection needles, etc.; the present invention provides a micro drill with a diameter of 0.5 mm, a puncture needle with a diameter of 0.2 mm, and an injection needle with a diameter of 0.3 mm. The micro drill is mainly used for drilling hard tissues, the puncture needle tool is mainly used for puncturing tissues, and the injection needle tool is used for injecting drugs into target tissues or aspirating tissue fluids; all operating tools are installed on a motor drive end that provides a separate degree of rotational freedom through a standardized structure.

[0016] The driving part of the four-degree-of-freedom plane guiding and positioning module includes a first feed unit and a third feed unit arranged along the X-axis direction, a second feed unit and a fourth feed unit arranged along the Y-axis direction, a second feed unit arranged away from the operating tool is fixedly installed on the driving end of the first feed unit, and an upper plane guiding module for limiting the position of the operating tool is fixedly installed on the driving end of the second feed unit. The single-plane guiding adjustment module composed of the first feed unit, the second feed unit and the upper plane guiding module is flipped on the plane where the central axis of the operating tool is located to obtain another single-plane guiding adjustment module composed of the third feed unit, the fourth feed unit and the lower plane guiding module. At this time, the first feed unit and the third feed unit are arranged in parallel in back to back and the second feed unit and the fourth feed unit are arranged in parallel in the same direction. The two groups of single-plane guiding adjustment modules are installed in the shell to form a four-degree-of-freedom plane guiding and positioning module.

[0017] The upper plane guide module includes an upper plane guide frame, one end of the upper plane guide frame away from the operating tool is fixed on the driving end of the second feed unit, and the other end of the upper plane guide frame is arranged in the spherical cavity with an upper plane guide ball that can rotate relative to the upper plane guide frame, and the upper plane guide ball is defined by an upper plane guide ball cover plate, and the operating tool can pass through the cylindrical hole of the upper plane guide ball; the lower plane guide module includes a lower plane guide frame, one end of the lower plane guide frame away from the operating tool is fixed on the driving end of the fourth feed unit, and the other end of the lower plane guide frame is arranged in the spherical cavity with a lower plane guide ball that can rotate relative to the lower plane guide frame, and the lower plane guide ball is defined by a lower plane guide ball cover plate, and the operating tool can pass through the cylindrical hole of the lower plane guide ball.

[0018] The four-degree-of-freedom plane guide positioning module also includes a guide sleeve, and the guide sleeve for the operating tool to pass through the cylindrical holes on the upper plane guide ball and the lower plane guide ball in turn. The upper part of the guide sleeve is fixed on the cylindrical hole of the upper plane guide ball and the guide sleeve can slide axially relative to the cylindrical hole on the lower plane guide ball, or the lower part of the guide sleeve is fixed on the cylindrical hole of the lower plane guide ball and the guide sleeve can slide axially relative to the cylindrical hole on the upper plane guide ball.

[0019] The feed unit is responsible for providing controllable feed motion. The feed unit includes a feed base, a feed motor, a feed reducer, a screw, a screw slider, and a feed flange. The feed motor is installed on the feed base. The feed reducer is installed at the output end of the feed motor. The output end of the feed reducer adopts a screw with a screw slider installed. The screw and the screw slider constitute a linear transmission mechanism. The feed flange is rigidly fixed to the screw slider as the output end and mounting mechanism of the feed unit.

[0020] A first plane guide shaft and a second plane guide shaft are arranged in parallel on both sides of the screw, and the screw slider is connected to the first plane guide shaft and the second plane guide shaft in the form of an axial hole; an anti-backlash spring is arranged on the first plane guide shaft and / or the second plane guide shaft, one end of the anti-backlash spring is fixed on the rigid body formed by the connecting flange and the screw slider, and the other end is fixed on the feed base. When the screw slider moves, the anti-backlash spring is always in a compressed state, and ensures that the anti-backlash spring still has elastic force in the minimum compression state.

[0021] During operation, the sixth rotation unit is connected to the fifth feed unit via a dovetail groove. The feed base of the fifth feed unit is rigidly connected to one end of the screw-in bracket, and the other end of the screw-in bracket is rigidly connected to the housing of the four-degree-of-freedom plane guide positioning module. Simultaneously, one end of the flexible transmission rod is fixed to the transmission rod connector on the sixth rotation unit, and the other end is rigidly fixed to the operating tool. It is required that the centerline of the end of the flexible transmission rod fixed to the transmission rod connector on the sixth rotation unit should be as coaxial as possible with the rotation axis of the transmission rod connector, and the centerline of the end of the flexible transmission rod fixed to the operating tool should also be as coaxial as possible with the rotation axis of the operating tool. This allows the motor in the four-degree-of-freedom plane guide positioning module to drive the operating tool to achieve translational motion along the X- and Y-axes and rotation around the X- and Y-axes. Simultaneously, the fifth feed unit can push the operating tool via the flexible connecting rod to achieve Z-axis feeding, and the sixth rotation unit can drive the operating tool to achieve rotation around the Z-axis by rotating the flexible connecting rod, thereby achieving six-degree-of-freedom manipulation of the operating tool.

[0022] The flexible rod-driven miniature six-degree-of-freedom minimally invasive operating device can be assembled in a modular manner. Connecting positioning holes and fixing threads of the same size are provided on the connecting flanges and feed bases of the five feed units. The feed units can be spliced ​​and fixed to each other. The four feed units form the driving part of the four-degree-of-freedom plane guide positioning module, and the remaining feed unit serves as the fifth feed unit. The two feed units in the four-degree-of-freedom plane guide positioning module can be assembled vertically according to the feed axis to form a single-plane motion module. The two single-plane motion modules can be flipped and stacked to form a double-plane motion module. The double-plane motion module is then integrated with the upper plane guide module and the lower plane guide module to form a standard four-degree-of-freedom plane guide positioning module. In this way, the first five degrees of freedom of this minimally invasive operating device can be formed by five standardized feed units. For the sixth degree of freedom, the operating tool, flexible transmission rod, and sixth rotation unit can be connected to form a single component, an interchangeable module that can be switched as needed. Depending on the surgical operating tool, the rotary motor requires pre-configured components of several different types. When used, the interchangeable module simply connects to the drive end of the fifth feed unit via a dovetail groove. This modular design reduces the structural complexity of minimally invasive surgical devices, facilitating mass production and enhancing component interchangeability and scalability.

[0023] A method for using a flexible rod-driven miniature six-degree-of-freedom minimally invasive operating device includes controlling an operating tool to reach a target position, and the steps are as follows:

[0024] a1. Coordinate system definition

[0025] First, define the coordinate system and define the coordinates of the center point O0 of the upper plane guide ball. for Coordinates of the center point O1 of the lower plane guide ball for The center point O0 of the upper plane guide ball and the center point O1 of the lower plane guide ball in the initial state of the device are located at the center of the upper plane guide ball in the initial state of the device. The origin of the device base coordinate system is defined to be located at the center point O0 of the upper plane guide ball in the initial state of the device. The X-axis direction is toward the front of the operator, the Z direction is perpendicular to the plane where the four-degree-of-freedom plane guide positioning module is located and is upward, and the Y-axis direction follows the right-hand rule. For the convenience of calculation, the coordinate system of the connection position of the operating tool is defined as the flange coordinate system, and the origin of the flange coordinate system coincides with the center point of the upper plane guide ball of the four-degree-of-freedom plane guide positioning module. In the initial state, the direction of the flange coordinate system coincides with the device base coordinate system. The origin of the operating tool coordinate system is defined to be located at the actual working position of the operating tool. For a slender rod-shaped operating tool, the origin of the operating tool coordinate system is defined as O tool Located on the line connecting O0 and O1, the specific position is determined by O tool The distance l from O0 is determined;

[0026] a2. Given the target posture of the operating tool, calculate the target motion position of each degree of freedom motor of the device

[0027] Input the target pose of the operating tool, expressed as a vector where x flan 、y flan 、z flan Respectively represent the translation values ​​of the end of the operating tool along the X-axis, Y-axis, and Z-axis in the device base coordinate system, ψ flan They respectively represent the rotation angle of the operating tool coordinate system relative to the device base coordinate system;

[0028] According to the coordinate system definition in step a1 above, the feed value of the first feed unit is J1 = x flan The feed value of the second feed unit is J2=y flan According to the trigonometric function relationship, the feed values ​​of the third feed unit and the fourth feed unit are:

[0029] In the above formula, h is the distance between the motion plane where the upper plane guide module is located and the motion plane where the lower plane guide module is located, which is a fixed value designed and determined when the device is constructed. is the desired rotation angle of the end tool around the X axis of the device base coordinate system. equal, is the desired rotation angle of the end tool around the Y axis of the device base coordinate system, and its value is the same as θ flan equal;

[0030] For the feed value J5 of the fifth feed unit, since the length of the flexible transmission rod remains unchanged, the shape of the flexible transmission rod from the output shaft of the rotary reducer at the end of the sixth rotation unit to the O0 point is a spatial curve, and it will change elastically with the position and direction of the operating tool. Therefore, the rigid body calculation method cannot be used to directly deduce the relationship between the end position of the operating tool and J5. It is obtained by calculating the inverse kinematic relationship between the elongation of the end of the operating tool in the static state and the feed value J5 of the fifth feed unit. At this time, ΔJ5=Δl, Δl is the elongation of the end of the operating tool; for the rotation value J6 of the sixth rotation unit, since it is transmitted by the flexible transmission rod, the rotational degree of freedom and the guide mechanism are decoupled from each other, so J6=ψ flan ;

[0031] a3. Control the motor to reach the target position

[0032] According to the calculated target position of each degree of freedom motor, the motor movement is controlled to drive the five feed units and the sixth rotation unit to drive the operating tool to move to the calculated value. At this time, the position of the end of the operating tool is the set target position.

[0033] A method for using a flexible rod-driven miniature six-degree-of-freedom minimally invasive operating device, the method also including a method for controlling an operating tool to perform adjustable telecentric motion. Telecentric motion means that during the movement of the operating tool, the operating tool axis always passes through a fixed point, which serves as the telecentric point. During minimally invasive surgery, the fixed point coincides with the minimally invasive surgical incision, thereby ensuring that the operating tool does not pull on the minimally invasive surgical incision channel during operation. The specific steps are as follows:

[0034] b1. Set the apocenter position

[0035] Far center point F of motion device target RCM Location coordinates The remote center point is required to be inside the motion space of the operating tool;

[0036] b2. Calculate the remote point constraint coefficient

[0037] Assume that the remote point constraint coefficient is n, then n is calculated by the following formula:

[0038] In the above formula: h is the distance between the upper plane guide module and the lower plane guide module, are the coordinates of the center point O0 of the upper plane guide ball and the center point O1 of the lower plane guide ball respectively;

[0039] b3. Calculate the motion constraint position of the far center point

[0040] set up is the rotation angle of the operating tool around the X-axis direction of the far-center point during the far-center movement, θ oy is the rotation angle of the operating tool around the Y-axis of the distal point during the distal point movement. When the micro six-degree-of-freedom minimally invasive operating device performs the distal point movement, the mathematical relationship between the center point O0 of the upper plane guide ball and the center point O1 of the lower plane guide ball can be expressed by the following formula:

[0041] Controlling the micro six-degree-of-freedom minimally invasive operating device to manipulate the center point O0 of the upper plane guide ball and the center point O1 of the lower plane guide ball to move according to the values ​​calculated by the above formula can ensure that the operating tool at the target position always passes through the distal point.

[0042] Furthermore, the method for controlling the operation tool to perform adjustable distal point movement also includes a distal point incremental motion control method, the specific steps are as follows: the center point O0 of the above plane guide ball is used as the control point, and the micro six-degree-of-freedom minimally invasive operation device is set to drive the center point of the upper plane guide ball control point O0 to move in a small increment The motion increment of the center point O1 of the plane guide ball under drive control can be calculated according to the following formula:

[0043] Moving in this increment can ensure that the micro six-degree-of-freedom minimally invasive operating device always maintains the distal point movement during the incremental movement process, that is, the distal point position can be freely adjusted.

[0044] In the coordinate system defined by the micro six-degree-of-freedom minimally invasive operating device provided by the present invention, the operating tool connection position coordinate system (flange coordinate system) is located at a fixed position on the mechanical device; the operating tool coordinate system represents the coordinates of the effective position on the tool (needle tip, clamp center, etc.), and the position of the operating tool coordinate system varies with the type of operating tool.

[0045] The present invention has the following advantages over the prior art:

[0046] The present invention provides a miniaturized, high-precision, micro six-degree-of-freedom minimally invasive operating device driven by a series-parallel drive mechanism and a flexible rod, which realizes the mechanical structure decoupling of XY plane motion and Z-axis motion, can effectively reduce the mechanical complexity of the minimally invasive operating device, and realize a compact structural design; the total weight of the micro six-degree-of-freedom minimally invasive operating device is only 72g, the output force can reach 3N, and it has a motion resolution of 10μm, which can realize tasks commonly used in microsurgery such as drilling, puncture, and drug injection.

[0047] The miniature six-degree-of-freedom minimally invasive operating device of the present invention provides a structural design method for a simplified six-degree-of-freedom operating device that is lightweight, has sufficient output force and precision, and simplifies the design of the six-degree-of-freedom motion structure while taking into account motion precision and load capacity, thereby helping to realize the application of miniaturized operating devices in real clinical microsurgery.

[0048] The miniature six-degree-of-freedom minimally invasive operating device of the present invention provides a modular six-degree-of-freedom operating device structural assembly method, which can complete the construction of the device through standardized modules, thereby reducing manufacturing costs and improving the reliability and maintainability of the device.

[0049] The miniature six-degree-of-freedom minimally invasive operating device of the present invention realizes effective control by establishing a forward / inverse kinematic model and an RCM motion model of the minimally invasive operating device, thereby meeting the spatial positioning and directional operation requirements of the minimally invasive operating device.

[0050] The micro six-degree-of-freedom minimally invasive operating device of the present invention provides a distal point motion control method based on the device, thereby realizing adjustable distal point motion, so that the device can adjust its own required distal point position according to different surgical scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] FIG1 is a front structural schematic diagram of a flexible rod-driven miniature six-degree-of-freedom minimally invasive surgical device provided by the present invention;

[0052] FIG2 is a schematic side view of the structure of a flexible rod-driven miniature six-degree-of-freedom minimally invasive surgical device provided by the present invention;

[0053] FIG3 is a schematic diagram of the internal structure of the flexible rod-driven miniature six-degree-of-freedom minimally invasive surgical device provided by the present invention;

[0054] FIG4 is a schematic structural diagram of the combination of the driving part and the guiding part in the four-degree-of-freedom plane guiding and positioning module provided by the present invention;

[0055] Figure 5 is a schematic structural diagram of the feeding unit provided by the present invention;

[0056] Figure 6 is a schematic diagram of the combined structure of the interchangeable module and the guide module provided by the present invention;

[0057] Figure 7 is a schematic diagram of an enlarged cross-section of the circled portion in Figure 6;

[0058] FIG8 is a schematic diagram showing the coordinate system definition of the flexible rod-driven miniature six-degree-of-freedom minimally invasive surgical device provided by the present invention;

[0059] FIG9 is a kinematic model of the micro six-degree-of-freedom minimally invasive surgical device provided by the present invention on the YOZ plane;

[0060] FIG10 is a kinematic model of the miniature six-degree-of-freedom minimally invasive surgical device provided by the present invention on the XOZ plane;

[0061] FIG11 is a YOZ plane projection view of the miniature six-degree-of-freedom minimally invasive operating device provided by the present invention in RCM kinematics;

[0062] FIG12 is an XOZ plane projection view of the miniature six-degree-of-freedom minimally invasive operating device provided by the present invention in RCM kinematics;

[0063] FIG13 is a graph showing the accuracy test results of a single feed unit provided by the present invention, wherein FIG13a is a graph showing the measured grating position when the single feed unit moves 5 steps at a time, FIG13b is a graph showing the measured grating position when the single feed unit moves 50 steps at a time, FIG13c is a graph showing the motion error when the single feed unit moves 5 steps at a time, and FIG13d is a graph showing the motion error when the single feed unit moves 50 steps at a time;

[0064] FIG14 is a diagram showing the accuracy test results of the flexible rod-driven miniature six-degree-of-freedom minimally invasive operating device provided by the present invention;

[0065] Figure 15 is a load capacity test result diagram of a single feed unit provided by the present invention, wherein Figure 15a is the thrust curve output by a single feed unit, Figure 15b is the tension curve output by a single feed unit, Figure 15c is the self-locking force of a single feed unit under push, and Figure 15d is the self-locking force under tension.

[0066] Among them: 100 - four-degree-of-freedom plane guide positioning module; 1 - feed unit; 10 - feed base; 11 - feed motor; 12 - feed reducer; 13 - lead screw; 14 - lead screw slider; 15 - feed flange; 16 - first plane guide shaft; 17 - second plane guide shaft; 18 - anti-backlash spring; 19 - slot module; 21 - upper plane guide module; 210 - upper plane guide frame; 211 - upper plane guide ball; 212 - upper plane guide ball cover; 22 - lower plane guide Toward module; 220—lower plane guide frame; 221—lower plane guide ball; 222—lower plane guide ball cover; 3—flexible transmission rod; 4—operating tool; 51—first feeding unit; 52—second feeding unit; 53—third feeding unit; 54—fourth feeding unit; 55—fifth feeding unit; 6—sixth rotating unit; 60—motor base; 61—rotating motor; 62—rotating reducer; 63—transmission rod connecting piece; 7—screw-in bracket; 200—interchangeable module. DETAILED DESCRIPTION

[0067] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, but not all of the embodiments.

[0068] As shown in Figure 1, the present invention provides a flexible rod-driven miniature six-degree-of-freedom minimally invasive manipulation device. To achieve six degrees of freedom, this minimally invasive manipulation device first designs a dual-plane serial-parallel mechanism to implement a four-degree-of-freedom planar guidance and positioning module 100 (i.e., the position adjustment module for the manipulation tool 4). This structure then constructs the feeding and rotational manipulation structure for the manipulation tool 4. To reduce the structural complexity of the minimally invasive manipulation device, a flexible transmission rod 3 is utilized to transmit the power from the feeding and rotational motion of the manipulation tool 4 to the four-degree-of-freedom planar guidance and positioning module 100. Taking into account precision, size, and cost factors, a micro-stepping motor-reducer-lead screw structure is selected to construct the feeding unit 1 to achieve the basic motion of the minimally invasive manipulation device. Through the controlled rotation of the stepper motor and the reduction of the gearbox and lead screw structure, high-precision motion resolution, output torque, and self-locking torque can be achieved. Based on the designed minimally invasive manipulation device structure, the forward and inverse kinematics and RCM kinematics of the minimally invasive manipulation device are simultaneously derived, and the motion control algorithm is constructed. Finally, based on the above work, the performance of the designed minimally invasive manipulation device is verified.

[0069] 1. Structural design

[0070] As shown in Figures 1-7, a flexible rod-driven miniature six-degree-of-freedom minimally invasive operating device is shown. The device as a whole is composed of a four-degree-of-freedom plane guiding and positioning module 100, a fifth feeding unit 55, a sixth rotating unit 6, a screw-in bracket 7, a flexible transmission rod 3 and an operating tool 4. The fifth feeding unit 55 and the driving part of the four-degree-of-freedom plane guiding and positioning module 100 use the same feeding unit 1. Four of the five feeding units 1 constitute the driving part of the four-degree-of-freedom plane guiding and positioning module 100, and the operating tool 4 can realize translation along the X-axis direction and the Y-axis direction, as well as bidirectional deflection around the X-axis and the Y-axis respectively under the action of the four-degree-of-freedom plane guiding and positioning module 100. The remaining feeding unit 1 serves as the fifth feeding unit 55 for pushing and pulling the operating tool 4 to run along the Z-axis direction. The fifth feeding unit 55 is installed on the shell of the four-degree-of-freedom plane guiding and positioning module 100 through a screw-in bracket 7. The output end of the fifth feeding unit 55 is equipped with a sixth rotating unit 6 that can realize the rotation of the operating tool 4 along the Z-axis direction. The output end of the sixth rotating unit 6 is connected to the operating tool 4 that passes through the four-degree-of-freedom plane guiding and positioning module 100 through a flexible transmission rod 3; the fifth feeding unit 55, the sixth rotating unit 6, and the four-degree-of-freedom plane guiding and positioning module 100 cooperate with each other to realize the fine and controllable movement of the six degrees of freedom of the operating tool 4.

[0071] Taking into account that different surgical tasks may have different requirements for instruments, rotation angles, rotation speeds and torques, the sixth rotation unit 6, the flexible transmission rod 3, and the operating tool 4 are combined to form an interchangeable module 200 that can be switched as needed, thereby providing a slot module 19 on the driving end of the fifth feed unit 55 to enable the switching and installation of different interchangeable modules 200, thereby completing the selection of different surgical tools.

[0072] In the aforementioned miniature six-degree-of-freedom minimally invasive operating device, the feed-rotation combination of the fifth feed unit 55 and the sixth rotation unit 6 is primarily responsible for the insertion / extraction and forward / reverse rotational degrees of freedom of the operating tool 4. The insertion and extraction of the operating tool 4 is controlled by the fifth feed unit 55, and the rotation of the operating tool 4 is controlled by the sixth rotation unit 6. The feed-rotation combination of the fifth feed unit 55 and the sixth rotation unit 6, which can provide two degrees of freedom, can be installed together with the four-degree-of-freedom planar guide and positioning module 100 to achieve six-degree-of-freedom motion of the minimally invasive operating device. However, due to the limited load-bearing capacity of the minimally invasive operating device itself, directly attaching the fifth feed unit 55 and the sixth rotation unit 6 to the four-degree-of-freedom planar guide and positioning module 100 not only requires additional tool connection design to strengthen the guide mechanism, but also increases the overall complexity. The present invention adopts a transmission method using a flexible transmission rod 3. The operating tool 4 and the sixth rotation unit 6 are connected by a super-elastic flexible transmission rod 3 (nickel-titanium alloy). The flexible transmission rod 3 is used to transmit thrust and torque. At the same time, the four-degree-of-freedom planar guidance and positioning module 100 drives the operating tool 4 to achieve position and direction adjustment of the operating tool 4. This solution achieves mechanical decoupling of the connection between the four-degree-of-freedom planar guidance and positioning module 100 and the feed rotation assembly, allowing the guidance and positioning and feed rotation processes to be controlled separately and independently, greatly simplifying the structure of the six-degree-of-freedom minimally invasive operation device.

[0073] The flexible transmission rod 3 is a slender rod with large deflection made of memory alloy wire. The center line of one end of the flexible transmission rod 3 fixed to the output end of the sixth rotation unit 6 is coaxial with the rotation axis of the output end of the sixth rotation unit 6, the center line of the other end of the flexible transmission rod 3 connected to the operating tool 4 is also coaxial with the rotation axis of the operating tool 4, and the central axis of the operating tool 4 is coaxial with the plane guide axis of the four-degree-of-freedom plane guide positioning module 100. The operating tool 4 is a rigid and slender tool that can rotate and feed for minimally invasive microsurgery operations; and the feed axis of the fifth feed unit 55, the rotation axis of the sixth rotation unit 6 and the plane guide axis of the four-degree-of-freedom plane guide positioning module 100 are not limited to parallel or coaxial axes.

[0074] As shown in Figure 3, the sixth rotation unit 6 includes a motor base 60, a rotating motor 61, a rotating reducer 62 and a transmission rod connecting member 63. The rotating motor 61 (servo motor, such as a stepping motor) is installed on the motor base 60 which is arranged into an embeddable structure (such as a dovetail groove structure). The output end of the rotating motor 61 is installed with a rotating reducer 62 (such as a planetary reducer). The output end of the rotating reducer 62 is installed with a transmission rod connecting member 63 connected to the flexible transmission rod 3. When the rotating motor 61 rotates, it can drive the transmission rod connecting member 63 to rotate.

[0075] As shown in Figures 3 and 4, the four-degree-of-freedom plane guiding and positioning module 100 contains a drive unit and a guide structure, which are mainly responsible for operating the translation of the operating tool 4 along the X-axis and Y-axis directions, as well as the rotational freedom around the X-axis and Y-axis directions (a total of four degrees of freedom); a channel is provided inside the guide structure, through which the operating tool 4 can pass and form a gap contact with the channel, so that the drive unit inside the four-degree-of-freedom plane guiding and positioning module 100 can drive the guide structure to adjust the translation and rotation of the operating tool 4 along the XY direction. The four-degree-of-freedom plane guiding and positioning module 100 is composed of four feeding units 1 (first feeding unit 51 to fourth feeding unit 54) and two plane guiding modules (guide structures). The four feeding units 1 are arranged in a double-layer plane, that is, the first feeding unit 51 and the second feeding unit 52 are connected in series to control the upper plane guide module 21 to move along the XY direction on the upper plane; the third feeding unit 53 and the fourth feeding unit 54 are connected in series to control the lower plane guide module 22 to move along the XY direction on the lower plane; the upper plane is parallel to the lower plane and there is a certain distance (typical value is 15mm). The upper plane guide module 21 and the lower plane guide module 22 both have a ball connection structure inside. Taking the upper plane guide module 21 as an example, the end of the upper plane guide frame 210 in the upper plane guide module 21 is provided with a hemispherical structure, and an upper plane guide ball 211 is placed inside it. The upper plane guide ball 211 is provided with a cylindrical hole inside, and the operating tool 4 can pass through the cylindrical hole. When the upper plane guide module 21 moves horizontally on the upper plane, it can drive the upper plane guide ball 211 to move, and the upper plane guide ball 211 drives the operating tool 4 to move. The structure of the lower plane guide module 22 is the same as that of the upper plane guide module 21 .

[0076] Specifically, the driving part of the four-degree-of-freedom plane guiding and positioning module 100 shown in Figure 4 includes a first feeding unit 51 and a third feeding unit 53 arranged along the X-axis direction, and a second feeding unit 52 and a fourth feeding unit 54 arranged along the Y-axis direction. The driving end of the first feeding unit 51 is fixedly mounted with a second feeding unit 52 set away from the operating tool 4, and the driving end of the second feeding unit 52 is fixedly mounted with an upper plane guiding module 21 for limiting the position of the operating tool 4. The single-plane guiding adjustment module composed of the first feeding unit 51, the second feeding unit 52 and the upper plane guiding module 21 is flipped on the plane where the central axis of the operating tool 4 is located to obtain another single-plane guiding adjustment module composed of the third feeding unit 53, the fourth feeding unit 54 and the lower plane guiding module 22. At this time, the first feeding unit 51 and the third feeding unit 53 are set in parallel in back to back and the second feeding unit 52 and the fourth feeding unit 54 are set in parallel in the same direction. The two groups of single-plane guiding adjustment modules are installed in the shell to form a four-degree-of-freedom plane guiding and positioning module 100.

[0077] The upper plane guide module 21 includes an upper plane guide frame 210, and the end of the upper plane guide frame 210 away from the operating tool 4 is fixed on the driving end of the second feeding unit 52, and the other end of the upper plane guide frame 210 is arranged in the spherical cavity with an upper plane guide ball 211 that can rotate relative to the upper plane guide frame 210, and the upper plane guide ball 211 is defined by an upper plane guide ball cover plate 212, and the operating tool 4 can pass through the cylindrical hole of the upper plane guide ball 211; the lower plane guide module 22 includes a lower plane guide frame 220, and the end of the lower plane guide frame 220 away from the operating tool 4 is fixed on the driving end of the fourth feeding unit 54, and the other end of the lower plane guide frame 220 is arranged in the spherical cavity with a lower plane guide ball 221 that can rotate relative to the lower plane guide frame 220, and the lower plane guide ball 221 is defined by a lower plane guide ball cover plate 222, and the operating tool 4 can pass through the cylindrical hole of the lower plane guide ball 221.

[0078] In order to improve the guiding stability of the four-degree-of-freedom plane guiding positioning module 100, a guide sleeve can also be provided, and the guide sleeve for the operating tool 4 to pass through the cylindrical holes on the upper plane guide ball 211 and the lower plane guide ball 221 in turn, and the upper part of the guide sleeve is fixed on the cylindrical hole of the upper plane guide ball 211 and the guide sleeve can slide axially relative to the cylindrical hole on the lower plane guide ball 221, or the lower part of the guide sleeve is fixed on the cylindrical hole of the lower plane guide ball 221 and the guide sleeve can slide axially relative to the cylindrical hole on the upper plane guide ball 211.

[0079] The feed unit 1 is responsible for providing controllable feed motion. As shown in Figures 5-7, the feed unit 1 consists of a feed motor 11 (generally a servo motor), a feed reducer 12, a screw 13, a screw slider 14, a first guide shaft 16, a second guide shaft 17, an anti-backlash spring 18, a connecting flange 15, and a feed base 10. The feed unit 1 controls the rotation of the feed motor 11 to drive the feed reducer 12 and the screw 13 to move, thereby pushing the screw slider 14 to feed and retract; the screw slider 14 is connected to the first guide shaft 16 and the second guide shaft 17 in the form of an axial hole. When the screw slider 14 moves in translation, it slides on the first guide shaft 16 and the second guide shaft 17 to ensure the accuracy of the linear motion; the connecting flange 15 is rigidly fixed to the screw slider 14, and the movement of the screw slider 14 can drive the connecting flange 15 to move simultaneously. A backlash-eliminating spring 18 is mounted on the second guide shaft 17. One end of the backlash-eliminating spring 18 is fixed to the rigid body formed by the connecting flange 15 and the lead screw slider 14, and the other end is fixed to the feed base 10. When the lead screw slider 14 moves, the backlash-eliminating spring 18 is always in a compressed state, ensuring that the backlash-eliminating spring 18 still has elastic force (preferably greater than 0.5N) in the minimum compression state, and ensuring that the elastic force of the spring does not exceed a set maximum value (preferably 3-5N) in the maximum compression state. This ensures that when the feed unit 1 moves, the lead screw slider 14 is always under a certain pressure, thereby eliminating the uncertainty of the transmission gap between the transmission systems. The lead screw 13 and the feed base 10 are both provided with mounting holes that can be connected to other components. A slot module 19 can be installed on the connecting flange 15 of the feed unit 1. The upper portion of the slot module 19 is provided with a detachable dovetail notch to enable manual disassembly and installation with other components (feed unit 1 or sixth rotating unit 6). For example, the motor base 60 of the sixth rotating unit 6 can be matched with the slot module 19.

[0080] Size and weight together reflect the portability of minimally invasive surgical devices. Size also determines the surgical space occupied by minimally invasive surgical devices. Therefore, to meet the various requirements of minimally invasive surgical devices, including volume, weight, precision, output force, and cost, the present invention utilizes a modular mini linear actuator as the feed unit 1. Its mini size, light weight, and low cost will facilitate its application in a wider range of surgical scenarios. In particular, in life science research, the inexpensive and compact minimally invasive device will greatly facilitate delicate surgical procedures on small animals such as mice and marmosets. Furthermore, due to its small footprint and precise motion, the designed minimally invasive surgical device also has potential applications in ophthalmology, neurosurgery, and other surgical procedures requiring precise manipulation in confined spaces. As shown in Figure 5, the feed unit 1 weighs no more than 5g and has a travel range of 8mm. It consists of a micro-stepping motor, a planetary reduction gearbox, and a lead screw. Thanks to the inherent characteristics of the stepping motor, the actuator's travel distance can be directly obtained through open-loop control commands. Furthermore, through transmission via the reduction gear and lead screw 13, the micro-stepping motor achieves sufficient output torque and motion precision. Considering that the gap is the key reason for the transmission error of the motor, gear, and screw scheme, we have optimized the design of the transmission gap of the feed unit 1. As shown in Figure 5, the anti-backlash spring 18 is pre-tightened to control the gap direction of the mechanical transmission process, so that the feed unit 1 has a certain gap size and the motor motion error caused by the gap is compensated in the later stage.

[0081] 2. Kinematics of Minimally Invasive Devices

[0082] According to the designed minimally invasive operating device, a quantitative connection between the various driving parts of the minimally invasive operating device and the movement of the operating tool 4 can be established through forward kinematics and inverse kinematics models.

[0083] (1) Coordinate system definition

[0084] As shown in Figure 8, define the coordinates of the center point O0 of the upper plane guide ball for Coordinates of the center point O1 of the lower plane guide ball for The center point O0 of the upper plane guide ball and the center point O1 of the lower plane guide ball in the initial state of the device are located at the center of the upper plane guide ball in the initial state of the device. The origin of the device base coordinate system is defined to be located at the center point O0 of the upper plane guide ball in the initial state of the device. The X-axis direction is toward the front of the operator, the Z direction is perpendicular to the plane where the four-degree-of-freedom plane guide positioning module is located and is upward, and the Y-axis direction follows the right-hand rule. For the convenience of calculation, the coordinate system of the connection position of the operating tool is defined as the flange coordinate system, and the origin of the flange coordinate system coincides with the center point of the upper plane guide ball of the four-degree-of-freedom plane guide positioning module. In the initial state, the direction of the flange coordinate system coincides with the device base coordinate system. The origin of the operating tool coordinate system is defined to be located at the actual working position of the operating tool. For a slender rod-shaped operating tool, the origin of the operating tool coordinate system is defined as O tool Located on the line connecting O0 and O1, the specific position is determined by O tool The distance l from O0 is determined.

[0085] (2) Positive kinematics

[0086] Considering the use of stepper motors as the drive for minimally invasive surgical devices, the forward kinematics derivation uses the number of stepper motor steps as the basic input unit. J1, J2, J3, and J4 represent the number of stepper motor steps with different degrees of freedom. Assume that the step length of the stepper motor is m and the distance between the upper and lower planes is h. Then: for any given J1, J2, J3, and J4, the coordinate of the center point O0 of the upper plane guide ball is and the coordinates of the center point O1 of the lower plane guide ball Calculated by formula (1-2).

[0087] For the flange coordinate system, its Z-axis direction vector can be calculated by formula (3):

[0088] As shown in Figures 9 and 10, the flange coordinate system rotates around the X-axis of the device base coordinate system. The angle of rotation of the flange coordinate system around the Y axis of the device base coordinate system can be calculated by formula (4) using the trigonometric relationship: The trigonometric relationship can be calculated to express the formula (5):

[0089] Since there is no rotational freedom around the Z axis, we can set That is, the flange coordinate system of the minimally invasive operating device does not rotate around the Z axis.

[0090] According to the above mathematical derivation, the pose vector of the flange coordinate system of the minimally invasive operating device can be obtained: According to the conversion formula from pose vector to pose matrix, we can get: robot T flan =fABC2MAT (V) (6)

[0091] According to the minimally invasive manipulation device shown in Figure 1, two degrees of freedom (DOFs) still exist between the manipulation tool coordinate system and the flange coordinate system: rotation and feed. Let the rotation angle be ψ, ψ = J5·q, where J5 is the number of rotation steps of the stepper motor 61, q is the step angle of the stepper motor, and l is the distance between the origin of the end coordinate of the manipulation tool 4 controlled by the fifth feed unit 55 and O0. The transformation matrix between the manipulation tool coordinate system and the flange coordinate system is (a composite coordinate transformation of linear translation and rotation about the Z axis):

[0092] According to the coordinate relationship, the coordinate transformation matrix of the final operating tool 4 relative to the device base coordinate system can be expressed by formula (8): robot T tool = robot T flan · flan T tool (8).

[0093] (3) Inverse kinematics

[0094] Inverse kinematics is the known position and posture of the operating tool 4 It is expected to find the motion value J of each motor of the minimally invasive operation device 1～6 Since the four-degree-of-freedom plane guide positioning module 100 has no freedom in the feed and rotation of the Z axis, the inverse kinematics problem is simplified to: the posture of the four parts of the operating tool is known Ask for J 1～4 According to the above coordinate system assumptions, the origin of the flange coordinate system always coincides with the center point O0 of the upper plane guide ball, so J can be calculated by formula (9-10) 1～2 Value:

[0095] According to the triangular relationship shown in Figures 9 and 10, J can be calculated by formula (11-12) 3～4 Value:

[0096] For J5, for the transmission of the flexible transmission rod 3, the rotational freedom and the guide mechanism are decoupled from each other, so J5 can be directly calculated as flan / q. Regarding J6, since the length of the flexible transmission rod 3 remains constant, its shape from the rotational end of the rotary motor 61 to the center point O0 of the upper planar guide ball is a spatial curve, and it elastically changes with the position and orientation of the planar guide module. Therefore, the relationship between the position of the operating tool 4 and J6 cannot be directly derived using rigid body calculation methods. However, the inverse kinematic relationship between the extension Δl of the operating tool 4 when the planar guide module is stationary and the rotation of the rotary motor 61 can be calculated, resulting in ΔJ6 = Δl / m.

[0097] (4) RCM kinematics

[0098] The minimally invasive manipulation device provided by the present invention can also achieve RCM motion (remote center point motion) and also has the function of adjusting the RCM point. The following derivation includes the RCM incremental control law required for the minimally invasive manipulation device under master-slave operation.

[0099] 1. RCM motion constraints

[0100] As shown in Figures 11 and 12, for the minimally invasive operating device, all guided movements are completed by the position changes of points O0 and O1 driven by the motor. Therefore, in order to achieve RCM movement, it is necessary to ensure that the control points O0, O1 and the RCM movement point are always on a straight line during the movement of the minimally invasive operating device. The triangular relationship shown in Figures 9 and 10 can be used to calculate the proportional coefficient n:

[0101] set up is the rotation angle of the operating tool 4 in the RCM motion around the X-axis direction of the RCM point, and θ oy is the rotation angle of the operating tool 4 in the RCM motion around the y-axis direction of the RCM point. According to equations (14) and (15), the constraint expression of the RCM angle can be obtained as follows:

[0102] It can be deduced from equations (14) and (15) that when the minimally invasive operating device performs RCM motion, the mathematical relationship between the center point O0 of the upper plane guide ball and the center point O1 of the lower plane guide ball is shown in equations (16)-(19).

[0103] In formulas (16)-(19), are the coordinates of the RCM points respectively. It can be seen that the manipulator designed in this study can realize the RCM control function, and the RCM points can be set as needed. The geometric constraint relationship between the center point O0 of the upper plane guide ball and the center point O1 of the lower plane guide ball can be determined by equations (18)-(19) when the minimally invasive operation device performs RCM motion. It can be seen that as long as the positions of the center point O0 of the upper plane guide ball and the center point O1 of the lower plane guide ball meet the positional relationship described in (18)-(19), the minimally invasive operation device can perform RCM motion.

[0104] 2. RCM incremental control

[0105] Laparoscopic surgery is mostly master-slave control, which requires that the next movement of the minimally invasive operating device at any motion position should also satisfy the RCM constraint, thereby achieving RCM incremental control. Considering equations (18) and (19) and when and When the time is small enough, equations (20) and (21) can be calculated.

[0106] The coefficient n can be calculated by formula (13), that is, It can be seen from Equations (20) and (21) that in any RCM motion state, as long as the motion increments of the center point O0 of the upper plane guide ball and the center point O1 of the lower plane guide ball meet a certain proportional relationship, incremental RCM motion can be achieved.

[0107] III. Performance Verification of Minimally Invasive Operating Devices

[0108] The research results will be presented in three aspects: first, performance testing of the system, then functional testing, and finally preliminary application verification on real biological materials.

[0109] (1) Performance test

[0110] 1. Accuracy test

[0111] In terms of accuracy testing, we first tested the accuracy of a single feeding unit 1 and then tested the overall accuracy of the minimally invasive operating device.

[0112] A feed unit 1 was randomly selected and used to drive the grating ruler. Its motion information was obtained by reading the grating ruler (DC11, Ditron, China, 0.1μm resolution). The test results are shown in Figure 13. It can be seen that when feed unit 1 moves 5 steps at a time, it moves with a resolution of 1μm and a motion error of less than ±1μm. When feed unit 1 moves 50 steps at a time, it moves stably with a resolution of 10μm and a motion error of less than ±2μm.

[0113] For the overall accuracy test of the minimally invasive operating device, a visual marker was fixed to the end of the operating tool 4, and the minimally invasive operating device was controlled to move in a rectangular trajectory. The motion trajectory was measured using a self-constructed stereo vision camera. The measurement trajectory is shown in Figure 14. It can be seen that the constructed minimally invasive operating device can complete 10 layers of rectangular trajectory motion (with a spacing of 50 μm) in a space of 1 mm square.

[0114] 2. Load capacity test

[0115] In terms of load capacity testing, we first tested the load capacity of a single feeding unit 1 and then tested the overall load capacity of the minimally invasive operating device.

[0116] First, the output thrust, output tension and self-locking ability of a single feed unit 1 are tested. A single feed unit 1 is fixed on a push-pull force gauge (China, Nscing Es / Su Test Company, SH-Ⅲ-500, resolution 0.1N), and the feed unit 1 is controlled by a controller to perform push-pull movements. As can be seen from Figure 15, a single feed unit 1 can output a maximum thrust of 6N and a maximum tension of about 9N (the imbalance between the output thrust and tension is mainly caused by the anti-backlash spring 18), and the self-locking force of the feed unit 1 is also measured by the push-pull force gauge. As can be seen from Figures 15a to 15d, a single feed unit 1 has a self-locking force of 5 to 6N under thrust and a self-locking force of 7 to 8N under tension. The above test results mean that the feed unit 1 can output a large driving force and at the same time maintain its own movement position under large external force disturbances.

[0117] Taking into account that the movement of the feeding unit 1 is ultimately applied to the end of the operating tool 4 through the flexible transmission rod 3, this will also cause a certain degree of driving force loss. We also tested the overall output load capacity of the minimally invasive operating device. By controlling the minimally invasive operating device to carry the operating tool 4 to contact the six-degree-of-freedom force sensor (Switzerland, Bota Systems AG, MEDUSA, resolution 0.01N) from different angles, the experiment was repeated 5 times in each direction. The maximum output force range of the ±X, ±Y, and Z-axis feeding working directions is shown in Table 1. It can be seen that the minimally invasive operating device can provide an output force greater than 3N in the working direction of the Z axis, and can also provide a driving force of about 1N in the lateral movement direction of XY.

[0118] Table 1 Maximum output force of operating tool 4 in each direction

[0119] Biological tissue is quite resilient, and surgical tools generate significant contact forces when interacting with tissue, requiring them to possess sufficient load-carrying capacity. Furthermore, to maintain the tool's current posture, it must possess a certain degree of self-locking capability, ensuring structural stability when subjected to tissue reaction forces. Performance test results demonstrate that the minimally invasive operating device we designed maintains high-precision motion resolution while also possessing Newton-level output force and self-locking force. A single actuator weighs no more than 5g, yet it can generate over 5N of thrust, pull, and self-locking force. This load capacity is sufficient to meet the load requirements of most surgical operations.

[0120] (2) Functional test

[0121] To demonstrate the potential of minimally invasive operating devices in real surgeries, we selected three common surgical tasks: drilling, puncture, and injection, to perform functional verification of the system.

[0122] 1. Drilling test

[0123] Drilling is a fundamental operation in cranial and skeletal surgeries. A minimally invasive manipulation device's drill tool was used to conduct drilling tests on both eggs and pig bones. Using a 0.5mm diameter drill bit, with feed and speed controlled by a remote control handle, the experimental results demonstrated that the minimally invasive manipulation device can accurately perform bone drilling tasks, both on eggshells and actual bone tissue.

[0124] 2. Puncture test

[0125] Puncture is another common surgical task. We conducted puncture experiments using a puncture needle. The target was pigskin. The minimally invasive manipulation device was used to create 16 micropores in a 4×4 array. The experimental results demonstrated that the minimally invasive manipulation device was capable of performing precise punctures on pigskin tissue, which exhibits a certain thickness and toughness.

[0126] 3. Injection test

[0127] The minimally invasive surgical procedure device provided by this invention can also deliver or aspirate liquids. Injection and aspiration are performed using a microsyringe pump (QHZS-001A, Yuanhang Power, China) in conjunction with the device's needle. Experimental results demonstrate that the minimally invasive surgical procedure device can deliver and aspirate liquids within a tiny space.

[0128] 3. Application Testing

[0129] (1) Small animal positioning and directional surgery guided by augmented reality

[0130] The minimally invasive operating device provided by the present invention can perform a variety of microsurgical operations such as drilling, puncture, and injection. However, how to accurately place the operating tool 4 into the target lesion area requires solving the target positioning problem. The present invention uses the principle of augmented reality to achieve positioning and directional path guidance of the operating tool 4. This method can be used for positioning and directional surgery of small animals such as mice and marmosets. After anesthesia, the target animal is fixed on the operating table and a Micro CT / or MRI scan is performed before the operation. The image data obtained by the scan can be used to accurately construct a personalized structural model of the mouse and perform surgical path planning at the same time. Since the operating table and the target animal are image scanned at the same time, the coordinate relationship between the surgical animal and the operating table can be obtained through the image. Combined with the relative position of the visual mark and the operating table (the relative position relationship is determined according to the processing drawing), the image model of the surgical animal and the surgical path can be registered under the visual mark. We use a 2D enhanced display to superimpose the surgical object model and the surgical path on the camera display image from different perspectives. During the operation, the doctor only needs to observe the model through the screen and control the minimally invasive operation device to adjust the operation tool 4 to coincide with the surgical path displayed by the augmented reality; the results show that the operation tool 4 reaches the target point more accurately.

[0131] (2) Ophthalmic microinjection experiments

[0132] The minimally invasive manipulation device provided by the present invention also has potential for application in ophthalmic surgery. In experiments using the minimally invasive manipulation device to perform fundus vascular puncture, an artificial eyeball phantom was first designed, with several simulated blood vessels less than 1 mm in diameter arranged at the fundus. An operating tool (4) was controlled to enter the eye from the side, using RCM motion to reach the target vessel and perform puncture and injection. The puncture results indicate that the minimally invasive manipulation device provided by the present invention is capable of performing lateral puncture and injection of simulated fundus vessels less than 1 mm in diameter.

[0133] The minimally invasive operation device provided by the present invention consists of five linear motion modules driven by low-cost micro-stepping motor reducers weighing no more than 5g and a replaceable micro-motor rotation module; based on a dual-plane mechanism, the 4-degree-of-freedom movement of the operating tool 4 in the XY direction is realized; the flexible transmission rod 3 is innovatively used for transmission, and the Z-axis rotation and feed freedom of the tip of the micro-operating tool 4 are realized while the mechanical structure is decoupled; the invasive operation device can realize six-degree-of-freedom control of microneedles, microdrills, and injection needles with a diameter of less than 0.5mm, with a motion resolution of 10um, a maximum output of 9N of thrust / pull force, and a self-locking force of about 6N; the total weight of the system is 72g and the volume is The device measures 75mmx53mmx71mm and can output an operating force of 3N on the Z-axis driven by the flexible transmission rod 3. Microneedle puncture and microhole drilling experiments have been carried out on in vitro biological tissues such as pig skin and pig bones, and the operation can be completed reliably. At the same time, examples of the application of the minimally invasive operating device in mice and fundus surgery are given, demonstrating the capabilities of the constructed manipulator in different surgical tasks. Compared with similar systems, the lightweight six-degree-of-freedom micromanipulator constructed by the minimally invasive operating device, which is driven by a serial-parallel guide mechanism and a flexible rod, can achieve clinically applicable operating force output with considerable precision, providing a potential tool for microsurgery operations with low-cost and portable requirements.

[0134] The above embodiments are intended only to illustrate the technical solutions of the present invention, and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. Such modifications or replacements do not deviate from the essence of the corresponding technical solutions of the embodiments of the present invention. Technologies not covered by the present invention can be implemented using existing technologies.

Claims

1. A flexible rod-driven miniature six-degree-of-freedom minimally invasive surgical device, characterized by: The device comprises five feeding units (1), wherein four feeding units (1) constitute the driving part of the four-degree-of-freedom plane guide positioning module (100), and the remaining feeding unit (1) serves as a fifth feeding unit (55) for pushing and pulling the operating tool (4) to move along the Z-axis direction; a sixth rotating unit (6) capable of rotating the operating tool (4) along the Z-axis direction is installed on the output end of the fifth feeding unit (55); the output end of the sixth rotating unit (6) is connected to the operating tool (4) that passes through the four-degree-of-freedom plane guide positioning module (100) through a flexible transmission rod (3); the operating tool (4) can respectively realize translation along the X-axis direction and the Y-axis direction, and bidirectional deflection around the X-axis and the Y-axis under the action of the four-degree-of-freedom plane guide positioning module (100); the fifth feeding unit (55), the sixth rotating unit (6), and the four-degree-of-freedom plane guide positioning module (100) cooperate with each other to realize the fine controllable movement of the six degrees of freedom of the operating tool (4).

2. The flexible rod-driven miniature six-degree-of-freedom minimally invasive surgical device according to claim 1, characterized in that: The fifth feeding unit (55) is mounted on the housing of the four-degree-of-freedom plane guide positioning module (100) via a screw-in bracket (7); a slot module (19) is configured on the output end of the fifth feeding unit (55), and the motor base (60) of the sixth rotating unit (6) can match the slot module (19); the sixth rotating unit (6), the flexible transmission rod (3), and the operating tool (4) are combined to form a replaceable module (200) that can be switched according to needs.

3. The flexible rod-driven miniature six-degree-of-freedom minimally invasive surgical device according to claim 1, characterized in that: The sixth rotating unit (6) includes a motor base (60), a rotating motor (61), a rotating reducer (62) and a transmission rod connecting piece (63). The rotating motor (61) is installed on the motor base (60) arranged in an embeddable structure, the rotating motor (61) is installed on the output end of the rotating motor (61), and the transmission rod connecting piece (63) connected to the flexible transmission rod (3) is installed on the output end of the rotating reducer (62). When the rotating motor (61) rotates, it can drive the transmission rod connecting piece (63) to rotate.

4. The flexible rod-driven miniature six-degree-of-freedom minimally invasive surgical device according to claim 1, characterized in that: The center line of one end of the flexible transmission rod (3) fixed to the output end of the sixth rotation unit (6) is coaxial with the rotation axis of the output end of the sixth rotation unit (6), the center line of the other end of the flexible transmission rod (3) connected to the operating tool (4) is also coaxial with the rotation axis of the operating tool (4), and the central axis of the operating tool (4) is coaxial with the plane guide axis of the four-degree-of-freedom plane guide positioning module (100); and the feed axis of the fifth feeding unit (55), the rotation axis of the sixth rotation unit (6) and the plane guide axis of the four-degree-of-freedom plane guide positioning module (100) are not limited to being parallel or coaxial.

5. The flexible rod-driven miniature six-degree-of-freedom minimally invasive surgical device according to claim 1, characterized in that: The flexible transmission rod (3) is a long and thin rod with large deflection, and the long and thin rod is made of memory alloy wire; the operating tool (4) is a rigid and thin tool capable of rotating and feeding required for minimally invasive microsurgery.

6. The flexible rod-driven miniature six-degree-of-freedom minimally invasive surgical device according to claim 1, characterized in that: The driving part of the four-degree-of-freedom plane guide positioning module (100) comprises a first feeding unit (51) and a third feeding unit (53) arranged along the X-axis direction, and a second feeding unit (52) and a fourth feeding unit (54) arranged along the Y-axis direction. The driving end of the first feeding unit (51) is fixedly mounted with a second feeding unit (52) arranged away from the operating tool (4). The driving end of the second feeding unit (52) is fixedly mounted with an upper plane guide module (21) for limiting the position of the operating tool (4). The single plane guide adjustment module composed of the first feeding unit (52) and the upper plane guide module (21) is flipped in the plane where the central axis of the operating tool (4) is located to obtain another single plane guide adjustment module composed of the third feeding unit (53), the fourth feeding unit (54) and the lower plane guide module (22). At this time, the first feeding unit (51) and the third feeding unit (53) are arranged in parallel in back to back directions, and the second feeding unit (52) and the fourth feeding unit (54) are arranged in parallel in the same direction. The two sets of single plane guide adjustment modules are installed in the shell to form a four-degree-of-freedom plane guide positioning module (100).

7. The flexible rod-driven miniature six-degree-of-freedom minimally invasive surgical device according to claim 6, characterized in that: The upper plane guide module (21) includes an upper plane guide frame (210), one end of the upper plane guide frame (210) away from the operating tool (4) is fixed to the driving end of the second feeding unit (52), and an upper plane guide ball (211) capable of rotating relative to the upper plane guide frame (210) is arranged in the spherical cavity at the other end of the upper plane guide frame (210), and the upper plane guide ball (211) is defined by an upper plane guide ball cover plate (212), and the operating tool (4) can pass through the cylindrical hole of the upper plane guide ball (211); The lower plane guide module (22) includes a lower plane guide frame (220), one end of the lower plane guide frame (220) away from the operating tool (4) is fixed to the driving end of the fourth feeding unit (54), and a lower plane guide ball (221) capable of rotating relative to the lower plane guide frame (220) is arranged in the spherical cavity at the other end of the lower plane guide frame (220), and the lower plane guide ball (221) is defined by a lower plane guide ball cover plate (222), and the operating tool (4) can pass through the cylindrical hole of the lower plane guide ball (221).

8. The flexible rod-driven miniature six-degree-of-freedom minimally invasive surgical device according to claim 7, characterized in that: The four-degree-of-freedom plane guide positioning module (100) further includes a guide sleeve, wherein the guide sleeve for the operating tool (4) to pass through is sequentially passed through the cylindrical holes on the upper plane guide ball (211) and the lower plane guide ball (221), the upper part of the guide sleeve is fixed on the cylindrical hole of the upper plane guide ball (211) and the guide sleeve can slide axially relative to the cylindrical hole on the lower plane guide ball (221), or the lower part of the guide sleeve is fixed on the cylindrical hole of the lower plane guide ball (221) and the guide sleeve can slide axially relative to the cylindrical hole on the upper plane guide ball (211).

9. The flexible rod-driven miniature six-degree-of-freedom minimally invasive surgical device according to any one of claims 1 to 8, characterized in that: The feed unit (1) comprises a feed base (10), a feed motor (11), a feed reducer (12), a lead screw (13), a lead screw slider (14), and a feed flange (15). The feed motor (11) is mounted on the feed base (10), the output end of the feed motor (11) is mounted with the feed reducer (12), the output end of the feed reducer (12) adopts a lead screw (13) mounted with the lead screw slider (14), the lead screw (13) and the lead screw slider (14) constitute a linear transmission mechanism, and the feed flange (15) is rigidly fixed to the lead screw slider (14) as the output end and mounting mechanism of the feed unit (1).

10. The flexible rod-driven miniature six-degree-of-freedom minimally invasive surgical device according to claim 9, characterized in that: A first plane guide shaft (16) and a second plane guide shaft (17) are arranged in parallel on both sides of the screw (13), and the screw slider (14) is connected to the first plane guide shaft (16) and the second plane guide shaft (17) in the form of an axial hole; an anti-backlash spring (18) is arranged on the first plane guide shaft (16) and / or the second plane guide shaft (17), one end of the anti-backlash spring (18) is fixed on the rigid body formed by the connecting flange (15) and the screw slider (14), and the other end is fixed on the feed base (10). When the screw slider (14) moves, the anti-backlash spring (18) is always in a compressed state, and it is ensured that the anti-backlash spring (18) still has elastic force in the minimum compressed state.

11. A method for using the flexible rod-driven miniature six-degree-of-freedom minimally invasive surgical device according to any one of claims 1 to 10, characterized in that: The method of use includes a method of controlling the operating tool to reach the target posture, and the steps are as follows: a1. Coordinate system definition First, define the coordinate system and define the coordinates of the center point O0 of the upper plane guide ball. for Coordinates of the center point O1 of the lower plane guide ball for The center point O0 of the upper plane guide ball and the center point O1 of the lower plane guide ball in the initial state of the device are located at the center of the upper plane guide ball in the initial state of the device. The origin of the device base coordinate system is defined to be located at the center point O0 of the upper plane guide ball in the initial state of the device. The X-axis direction is toward the front of the operator, the Z direction is perpendicular to the plane where the four-degree-of-freedom plane guide positioning module is located and is upward, and the Y-axis direction follows the right-hand rule. For the convenience of calculation, the coordinate system of the connection position of the operating tool is defined as the flange coordinate system, and the origin of the flange coordinate system coincides with the center point of the upper plane guide ball of the four-degree-of-freedom plane guide positioning module. In the initial state, the direction of the flange coordinate system coincides with the device base coordinate system. The origin of the operating tool coordinate system is defined to be located at the actual working position of the operating tool. For a slender rod-shaped operating tool, the origin of the operating tool coordinate system is defined as O tool Located on the line connecting O0 and O1, the specific position is determined by O tool The distance l from O0 is determined; a2. Given the target posture of the operating tool, calculate the target motion position of each degree of freedom motor of the device Input the target pose of the operating tool, expressed as a vector where x flan 、y flan 、z flan Respectively represent the translation values ​​of the end of the operating tool along the X-axis, Y-axis, and Z-axis in the device base coordinate system, ψ flan They respectively represent the rotation angle of the operating tool coordinate system relative to the device base coordinate system; According to the coordinate system definition in step a1 above, the feed value of the first feed unit is J1 = x flan The feed value of the second feed unit is J2=y flan According to the trigonometric function relationship, the feed values ​​of the third feed unit and the fourth feed unit are: In the above formula, h is the distance between the motion plane where the upper plane guide module is located and the motion plane where the lower plane guide module is located, which is a fixed value designed and determined when the device is constructed. is the desired rotation angle of the end tool around the X axis of the device base coordinate system. equal, is the desired rotation angle of the end tool around the Y axis of the device base coordinate system, and its value is the same as θ flan equal; The feed value J5 of the fifth feed unit is obtained by calculating the inverse kinematic relationship between the extension of the operating tool end in the static state and the feed value J5 of the fifth feed unit. At this time, ΔJ5 = Δl, where Δl is the extension of the operating tool end. For the rotation value J6 of the sixth rotation unit, since it is driven by a flexible transmission rod, the rotational freedom degree and the guide mechanism are decoupled from each other, so J6 can be directly calculated as ψ flan ; a3. Control the motor to reach the target position According to the calculated target position of each degree of freedom motor, the motor movement is controlled to drive the five feed units and the sixth rotation unit to drive the operating tool to move to the calculated value. At this time, the position of the end of the operating tool is the set target position.

12. The method for using the flexible rod-driven miniature six-degree-of-freedom minimally invasive surgical device according to claim 11, characterized in that: The method of use also includes a method for controlling the operating tool to perform adjustable distal point movement. The distal point movement means that during the movement of the operating tool, the operating tool axis always passes through a fixed point known as the distal point. During minimally invasive surgery, this fixed point coincides with the minimally invasive surgical incision, thereby ensuring that the operating tool does not pull on the minimally invasive surgical incision channel during operation. The specific steps are as follows: b1. Set the apocenter position Far center point F of motion device target RCM Location coordinates The remote center point is required to be inside the motion space of the operating tool; b2. Calculate the remote point constraint coefficient Assume that the remote point constraint coefficient is n, then n is calculated by the following formula: In the above formula: h is the distance between the upper plane guide module and the lower plane guide module, are the coordinates of the center point O0 of the upper plane guide ball and the center point O1 of the lower plane guide ball respectively; b3. Calculate the motion constraint position of the far center point set up is the rotation angle of the operating tool around the X-axis direction of the far-center point during the far-center movement, θ oy is the rotation angle of the operating tool around the Y-axis of the distal point during the distal point movement. When the micro six-degree-of-freedom minimally invasive operating device performs the distal point movement, the mathematical relationship between the center point O0 of the upper plane guide ball and the center point O1 of the lower plane guide ball can be expressed by the following formula: Control the micro six-degree-of-freedom minimally invasive operating device to manipulate the center point O0 of the upper plane guide ball and the center point O1 of the lower plane guide ball to move according to the values ​​calculated by the above formula to ensure that the operating tool always passes through the distal point at the target position; Furthermore, the method for controlling the operation tool to perform adjustable distal point movement also includes a distal point incremental motion control method, the specific steps are as follows: the center point O0 of the above plane guide ball is used as the control point, and the micro six-degree-of-freedom minimally invasive operation device is set to drive the center point of the upper plane guide ball control point O0 to move in a small increment The motion increment of the center point O1 of the plane guide ball under drive control can be calculated according to the following formula: Moving in this increment can ensure that the micro six-degree-of-freedom minimally invasive operating device always maintains the distal point movement during the incremental movement process, that is, the distal point position can be freely adjusted.

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