A braided flexible manipulator based on shape sensing using distributed fiber Bragg gratings and its feedback control method.

Abstract

This invention relates to the field of minimally invasive surgical instrument technology, and in particular to a braided flexible manipulator based on distributed fiber grating (FBG) shape sensing and its feedback control method. The manipulator includes a double-layer braided skeleton, which is composed of an inner braided tube and an outer braided tube tightly fitted together. The inner braided tube is composed of multiple strands of capillary spirally woven together, and an optical fiber sensing unit containing an FBG is inserted inside the capillary. A flexible drive wire is also provided within the double-layer braided skeleton. This invention, through its double-layer braided skeleton structure and the integration of an optical fiber with FBG functionality, enables the flexible manipulator with a braided structure to reliably sense the spatial posture of each joint of the manipulator with minimal structural burden, thereby achieving shape reconstruction and motion feedback control of the manipulator.

Description

Technical Field

[0001] This invention relates to the field of minimally invasive surgical instruments, specifically to a braided flexible manipulator based on shape perception using distributed fiber gratings and its feedback control method. Background Technology

[0002] Minimally invasive surgery is a method of performing surgery through tiny incisions or natural cavities, aiming to reduce damage to the patient's body and accelerate postoperative recovery time. Traditional minimally invasive surgical arms often use rigid or semi-rigid structures, which suffer from insufficient flexibility and difficulty in adapting to complex anatomical environments.

[0003] To improve surgical flexibility and adaptability, a woven flexible operating arm is employed. The double-layered woven structure provides excellent flexibility, allowing the operating arm to move flexibly within confined surgical spaces and adapt to complex surgical environments. Simultaneously, it possesses a certain degree of rigidity and stability, maintaining its shape and function under external forces. However, while the woven flexible operating arm can achieve bending movements, it lacks effective shape sensing mechanisms and cannot accurately perceive the bending status of its joints in real time. This makes it difficult for surgeons to accurately grasp the shape and position of the operating arm during operation, potentially leading to intraoperative positioning errors and increasing surgical risks.

[0004] Traditional shape sensing technologies mainly rely on electromagnetic tracking or visual imaging. Electromagnetic tracking technology senses shape by detecting changes in the position and orientation of an object in an electromagnetic field, but it is susceptible to interference from metal instruments or external magnetic fields, leading to positioning distortion. Visual imaging technology relies on cameras to capture the shape of the target, but it suffers from problems such as line-of-sight obstruction and light sensitivity. At the same time, the above technologies generally use external sensor layouts, resulting in the separation of sensors from the manipulator structure, insufficient integration, and susceptibility to external environmental influences. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a woven flexible manipulator based on distributed fiber Bragg gratings for shape sensing and its feedback control method.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a braided flexible manipulator based on distributed fiber grating for shape sensing, comprising a double-layer braided skeleton, wherein the double-layer braided skeleton is composed of an inner braided tube and an outer braided tube tightly fitted together, wherein the inner braided tube is a tubular mesh structure spirally woven with multiple strands of capillary tubes, wherein an optical fiber sensing unit containing FBG is inserted inside the capillary tube, and a flexible drive wire is provided inside the flexible manipulator.

[0007] In some embodiments, the outer braided tube is a tubular mesh structure spirally braided with braided threads (1-2), and the inner braided tube and the outer braided tube are coaxially nested together, with the braiding angle of the outer braided tube being smaller than that of the inner braided tube.

[0008] In some embodiments, the fiber optic sensing unit and the flexible drive wire are located on the same end side of the double-layer braided skeleton at one of their external ends.

[0009] In some embodiments, a silicone tube is provided on the outer surface of the optical fiber sensing unit, and the silicone tube is tightly fitted to the inner wall of the capillary.

[0010] In some embodiments, at least three capillaries with fiber optic sensing units are provided on the inner braided tube, and the capillaries with fiber optic sensing units are evenly distributed circumferentially.

[0011] In some embodiments, the fiber optic sensing unit is an optical fiber with multiple FBGs distributed on it. The number of FBGs on the optical fiber is the same as the number of joints on the operating arm, and all the FBGs on the optical fiber are arranged axially to correspond one-to-one with the joint areas on the operating arm. All the FBGs on the optical fiber are arranged sequentially from small to large according to the center wavelength range of the FBGs, and they do not overlap with each other.

[0012] In some embodiments, the fiber optic sensing unit is an optical fiber with multiple equally spaced fiber optic groups (FBGs). The FBGs on the optical fiber are axially distributed in the same number of joint regions of the operating arm. All the FBGs on the optical fiber are arranged sequentially according to the center wavelength range of the FBGs, from small to large, and without overlapping each other.

[0013] In some embodiments, the flexible manipulator is provided with at least three flexible drive wires corresponding to the end of each joint. One end of the flexible drive wire located at the same joint is evenly distributed and fixed along the circumferential distribution of the grid unit of the double-layer braided skeleton, and only one flexible drive wire is provided in each grid unit. The other end of all the flexible drive wires extends axially along the inner wall of the inner braided tube and passes through the manipulator to connect to the drive module. The drive module includes a drive unit and a controller. One drive unit is provided at each flexible drive wire, and all drive units are communicatively connected to the controller.

[0014] To achieve the above objectives, the present invention also provides the following technical solution: a feedback control method for a braided flexible manipulator based on distributed fiber Bragg gratings for shape sensing, employing the aforementioned braided flexible manipulator, the steps of which are as follows:

[0015] (1) The fiber optic connectors of the fiber optic sensing unit are connected to the fiber optic demodulator. The fiber optic demodulator establishes communication with the host computer and collects wavelength data in the fiber optic sensing unit in real time and transmits it to the host computer.

[0016] (2) Record the reference center wavelength of each FBG in the reference state of the operating arm, build a calibration experimental platform, accurately measure the actual bending angle and direction of each joint of the operating arm under different postures, record the FBG wavelength change data collected by the fiber demodulator in the corresponding state and analyze and process it, determine the mapping relationship between the bending angle and direction of each joint of the operating arm and the FBG wavelength change, and store it in the host computer.

[0017] (3) When the operating arm is bent and deformed, the FBG is subjected to strain and the center wavelength changes accordingly. After the host computer receives the real-time wavelength data transmitted by the fiber demodulator, it accurately calculates and analyzes the spatial posture of each joint of the operating arm according to the pre-established mapping relationship and spatial coordinate transformation algorithm. By fusing the posture information of each joint, the overall three-dimensional shape of the operating arm is reconstructed.

[0018] (4) The fiber optic sensing unit can detect the end-joint pose information of the manipulator and feed it back to the drive module. By comparing the actual pose with the target pose and combining the kinematic model of the manipulator, the pulling amount of the flexible drive wire assembly is controlled so that the actual pose of the end of the manipulator is close to the target pose.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] The operating arm of this invention uses a double-layer woven skeleton as its base, which has good flexibility and can move flexibly, conveniently, safely and smoothly in narrow surgical spaces, adapting to complex surgical environments.

[0021] The operating arm of the present invention adopts an integrated structural and functional design, integrating the fiber optic sensing unit inside the braided structure, avoiding spatial interference and operating arm motion coupling errors that may be caused by external sensors, and improving the reliability and anti-interference performance of flexible sensing.

[0022] The fiber optic sensing unit of the present invention can realize real-time shape perception of the operating arm in minimally invasive surgery, including the bending angle and direction of each joint of the operating arm, providing surgeons with an intuitive and accurate view of the shape of the operating arm.

[0023] 4. The fiber optic sensing unit of the present invention can detect and provide feedback on the end pose of the control arm, so that its actual end pose converges to the target trajectory, providing highly responsive motion correction capability for surgical operations and improving the safety and success rate of surgical operations.

[0024] Details of one or more embodiments of this application are set forth in the following drawings and description to make other features, objects and advantages of this application more readily apparent. The embodiments of this application will provide a detailed description and understanding of the application. Attached Figure Description

[0025] Figure 1This is a three-dimensional structural diagram of the present invention;

[0026] Figure 2 This is a schematic diagram of the enlarged distal structure of the double-layer braided skeleton of the present invention;

[0027] Figure 3 This is a magnified schematic diagram of the proximal end of the double-layer braided skeleton of the present invention;

[0028] Figure 4 This is a schematic diagram of the bending deformation of the double-layer woven skeleton of the present invention;

[0029] Figure 5 This is a schematic diagram of the three-dimensional structure of the fiber optic sensing unit of the present invention;

[0030] Figure 6 This is a schematic cross-sectional view of the fiber optic sensing unit of the present invention;

[0031] Figure 7 This is a schematic diagram illustrating the shape reconstruction and motion feedback control of the manipulator using a fiber optic sensing unit.

[0032] In the diagram: 1-1, capillary tube; 1-2, braided wire; 1-3, distal end; 1-4, proximal end; 1-5, fiber optic connector; 1-6, fiber optic sensing unit; 1-7, flexible drive wire; 5-1, silicone tube; 6-1, equidistant FBG; 7-1, linear motor; 7-2, driver; 7-3, controller; 7-4, fiber optic demodulator; 7-5, host computer. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] While the woven structure in traditional minimally invasive surgical arms enables multi-degree-of-freedom bending motion, it lacks embedded sensing units for real-time monitoring of its own shape. When the arm moves within narrow cavities, it cannot acquire data on joint bending angles and directions, causing deviations between the movement trajectory and the expected path. This deviation directly affects the positioning accuracy of the end effector, potentially leading to tissue injury or missed lesion detection in complex anatomical environments, thus reducing surgical safety and operational efficiency.

[0035] If the above problems are not addressed, the motion control of the manipulator will continue to rely on empirical predictions and offline calibration, making it impossible to establish a closed-loop feedback mechanism. The lack of real-time intraoperative morphological data will directly limit the development of automated surgical systems and hinder the advancement of precision medicine technologies. Furthermore, the manipulator's motion stability and safety in complex anatomical environments cannot meet clinical needs, resulting in a limited range of indications for minimally invasive surgery and hindering its widespread application in related fields.

[0036] Faced with the aforementioned challenges, this application first considers how to achieve high-precision shape perception in a braided flexible manipulator. Traditional external sensors are difficult to integrate into narrow cavities due to size limitations and are susceptible to electromagnetic interference or line-of-sight obstruction. To address this, this application attempts to embed the sensing unit into the manipulator's main body structure, but the compatibility issue between the sensor and the drive mechanism needs to be resolved. Further analysis reveals that fiber optic grating sensors, with their small size and electromagnetic interference resistance, are suitable for embedding in the braided skeleton. However, directly implanting the fiber can easily lead to signal distortion due to deformation of the braided structure. To address this, this application proposes encapsulating the fiber within a capillary tube and forming a strain transmission path through helical braiding, thus protecting the fiber while ensuring effective transmission of bending strain. Simultaneously, to achieve synchronous multi-joint motion control, a distributed drive wire layout is adopted, allowing each joint to be driven independently or collaboratively, combined with wavelength encoding technology to achieve synchronous multi-joint shape calculation.

[0037] In this regard, such as Figures 1 to 7 As shown, this application proposes a braided flexible manipulator based on distributed fiber grating (FBG) for shape sensing. The manipulator includes a double-layered braided skeleton, consisting of an inner braided tube and an outer braided tube tightly fitted together. The inner braided tube is a tubular mesh structure spirally woven from multiple strands of capillary tubes 1-1. An optical fiber sensing unit 1-6 containing an FBG is inserted inside the capillary tube 1-1. A flexible drive wire 1-7 is fitted inside the flexible manipulator. The flexible drive wire 1-7 is axially pulled by a drive module to achieve joint bending motion of the manipulator. Complex spatial movements of the manipulator are achieved by axially pulling the flexible drive wire 1-7 at different joints. The bending shape of the manipulator, including the bending angle and direction, is monitored in real time by the wavelength change of the FBG.

[0038] The double-layer braided skeleton refers to a composite tubular support structure composed of an inner and outer braided structure. The inner and outer layers are made of different materials or braiding methods. Specifically, it can be achieved by spirally braiding multiple strands of capillary tubes 1-1 to form the inner layer and spirally braiding braided threads 1-2 to form the outer layer. The two layers are arranged in an interlaced manner to form a whole. This structure enhances the mechanical strength and deformation resistance of the operating arm while ensuring flexibility. The inner braided tube refers to the tubular mesh structure located inside the double-layer braided skeleton. Specifically, it is formed by spirally braiding multiple strands of capillary tubes 1-1. The capillary tubes 1-1 can accommodate fiber optic sensing units 1-6. This structure provides a protective channel for the optical fiber and ensures that strain is effectively transmitted to the optical fiber. The fiber optic sensing unit 1-6 refers to a sensor assembly integrating fiber Bragg gratings. Specifically, it can be achieved by arranging multiple FBGs on a single optical fiber. The FBGs are distributed along the optical fiber axis and correspond to the joint area of ​​the operating arm. By detecting the wavelength changes of the FBGs, the bending angle and direction information of the operating arm can be obtained in real time. Among them, the flexible drive wire 1-7 refers to the traction element used to control the movement of the manipulator arm. It is made of a high elastic modulus material. The axial tension is applied by the drive module to cause the manipulator arm to bend. The drive wires at different joints can be independently controlled to achieve multi-degree-of-freedom spatial movement. The drive module refers to the actuator that controls the movement of the flexible drive wire 1-7. It uses a motor or pneumatic device in conjunction with the controller 7-3 to achieve precise tension adjustment. The controller 7-3 coordinates the tension of multiple drive wires according to the movement command to achieve the target posture.

[0039] The core innovation of this application lies in embedding the distributed fiber optic grating sensing unit into the inner braided tube capillary 1-1 of the double-layer braided skeleton, combined with the axially traction flexible drive wire 1-7, to realize real-time monitoring of the bending shape of the manipulator and multi-joint collaborative motion feedback control. The bending angle and direction of each joint of the manipulator are directly reflected by the change of FBG wavelength, which solves the problem that traditional flexible manipulators lack integrated shape perception capability and motion feedback control.

[0040] The working process and principle of this application are as follows: a braided flexible manipulator based on distributed fiber grating (FBG) for shape sensing includes a double-layer braided skeleton. The double-layer braided skeleton is composed of an inner braided tube and an outer braided tube tightly fitted together. The inner braided tube is formed by spirally braiding multiple strands of capillary tubes 1-1 to form a tubular mesh structure. An optical fiber sensing unit 1-6 containing an FBG is inserted inside the capillary tube 1-1. A flexible drive wire 1-7 is installed inside the flexible manipulator.

[0041] The flexible drive wires 1-7 are axially pulled by the drive module to achieve the joint bending motion of the manipulator. Axial pulling of the flexible drive wires 1-7 at different joints can realize complex spatial movements of the manipulator. The wavelength change of the FBG is used to monitor the bending shape of the manipulator in real time, including the bending angle and direction.

[0042] Fiber optic sensing units 1-6 are embedded within capillary tube 1-1, and a strain transfer path is formed through helical braiding. This structure protects the fiber while ensuring effective transfer of bending strain. The distributed drive wire layout allows each joint to be driven independently or collaboratively. Wavelength encoding technology is used to achieve synchronous calculation of the morphology of multiple joints.

[0043] When the manipulator bends, the deformation of the braided skeleton causes strain in the fiber optic sensing units 1-6, resulting in a change in the center wavelength of the FBG. The fiber optic demodulator 7-4 collects the wavelength data and transmits it to the host computer 7-5. The host computer 7-5 calculates the spatial orientation of each joint of the manipulator based on the pre-established mapping relationship and spatial coordinate transformation algorithm, and reconstructs the overall three-dimensional shape of the manipulator.

[0044] The drive module compares the actual and target poses of the end effector with the end effector's pose based on the feedback from the fiber optic sensing units 1-6. Combining this with the manipulator's kinematic model, it controls the tension of the flexible drive wires 1-7, ensuring that the actual end effector pose closely approximates the target pose. This closed-loop control mechanism improves the positioning accuracy and motion stability of the manipulator.

[0045] As a preferred embodiment, the solution of this application is specifically implemented as follows:

[0046] The braided flexible manipulator employs a double-layer braided skeleton structure. The inner braided tube is made of multiple strands of capillary tubes spirally woven together to form a tubular mesh structure. The outer braided tube is made of braided yarns spirally woven together to form a tubular mesh structure, which is then coaxially nested with the inner braided tube and tightly fitted together.

[0047] Fiber optic sensing units 1-6 are encapsulated within capillary tube 1-1. Multiple fiber optic gratings (FBGs) are distributed on the fiber, the number matching the number of joints in the manipulator arm. The axial direction of each FBG corresponds one-to-one with the joint region. The FBGs are arranged sequentially from smallest to largest according to their center wavelength range, without overlapping, facilitating grating number identification during data acquisition. A silicone tube 5-1 is mounted on the outer surface of the fiber optic sensing unit 1-6, tightly fitting against the inner wall of capillary tube 1-1 for protection and fixation.

[0048] At least three capillaries 1-1, each containing an optical fiber sensing unit 1-6, are arranged circumferentially on the inner braided tube. At least three flexible drive wires 1-7 are arranged at the end of each joint, evenly distributed and fixed along the circumferential direction of the grid unit. The other end of the drive wire extends axially along the inner wall of the inner braided tube and passes through the operating arm, connecting to the drive module.

[0049] The drive module includes drive units and a controller 7-3. Each flexible drive wire 1-7 corresponds to a drive unit, and all drive units are communicatively connected to the controller 7-3. Bending of the joint is achieved by axially pulling the drive wires at the same joint end, and complex spatial movements are achieved by pulling the drive wires at different joint ends.

[0050] The communication ends of the fiber optic sensing unit 1-6 and the flexible drive wire 1-7 are located at the same end of the double-layer braided skeleton, and are connected to the fiber optic demodulator 7-4 and the drive module, respectively. The fiber optic demodulator 7-4 establishes communication with the host computer 7-5 to acquire and transmit wavelength data in real time. The host computer 7-5 calculates the posture of each joint according to the pre-established mapping relationship and reconstructs the three-dimensional shape of the manipulator.

[0051] Through the above-described scheme, this application achieves high-precision shape perception of the braided flexible manipulator. The embedded fiber optic grating sensor network overcomes the limitations of traditional external sensors, avoiding electromagnetic interference and line-of-sight obstruction problems. The combination of distributed drive wire layout and wavelength coding technology enables multi-joint cooperative motion control and synchronous shape calculation.

[0052] This integrated design enhances the manipulator's adaptability and safety in complex anatomical environments. Real-time morphological data feedback establishes a closed-loop control mechanism, significantly improving end-effector positioning accuracy. The manipulator can precisely track a pre-set path within narrow cavities, reducing the risk of tissue damage.

[0053] like Figures 1 to 4 As shown, this application further proposes that the outer braided tube is a tubular mesh structure made of braided yarn 1-2 spirally braided, and the inner braided tube and the outer braided tube are coaxially nested and connected as one unit, and the braiding angle of the outer braided tube is smaller than that of the inner braided tube.

[0054] The braiding angle is the angle between the braided thread or capillary and the central axis of the corresponding braided tube. The inner and outer braided tubes are braided in the same spiral pattern to form a single-layer braided tube structure. The inner and outer braided tubes are coaxially nested and connected to form a double-layer braided skeleton structure. The braiding angle of the inner braided tube is greater than that of the outer braided tube. The inner braided tube serves as a support structure, and the outer braided tube serves as a wrapping structure to limit the radial expansion of the inner layer.

[0055] Specifically, the spirally braided tubular mesh structure is formed by the braiding threads 1-2 interlacing in both forward and reverse directions along the spiral path to create uniformly distributed mesh units. These mesh units maintain a continuous arrangement in both the axial and circumferential directions. The inner braided tube employs the same braiding method as the outer braided tube. The braiding threads 1-2 can be made of materials that balance strength and elastic modulus. The mesh units formed by the spiral braiding uniformly bear external loads, avoiding localized stress concentration, while allowing the manipulator to release strain energy through mesh deformation when bending.

[0056] As a preferred embodiment, the solution of this application is specifically implemented as follows:

[0057] The spiral angle of braided thread 1-2 is controlled by adjusting the braiding machine parameters to ensure that the braiding angle of braided thread 1-2 is less than the braiding angle of capillary tube 1-1. For example, the braiding angle of the inner braided tube is 45° and the braiding angle of the outer braided tube is 30°. After the inner and outer braided tubes are completed, they are made into a whole by coaxial nesting.

[0058] Through the above technical solution, this application achieves a balance between flexibility and strength after the inner and outer braided tubes are combined. The inner braided tube adopts a tubular mesh structure with capillary 1-1 spiral braiding, giving the operating arm good flexibility and operability, allowing it to move flexibly in narrow spaces. The outer braided tube adopts a tubular mesh structure with braided yarn 1-2 spiral braiding, which can limit the radial expansion of the inner braided tube. At the same time, the tubular mesh structure also provides a certain degree of support strength, allowing the operating arm to maintain its shape stability even when bent. In addition, the tight fit between the outer and inner braided tubes further enhances the stability of the overall structure and improves the load-bearing capacity and control precision of the operating arm.

[0059] like Figure 1 , 3 As shown in Figures 4 and 7, this application further proposes that the fiber optic sensing unit 1-6 and the flexible drive wire 1-7 are located on the same end side of the double-layer braided skeleton, and are respectively connected to the fiber optic demodulator 7-4 and the drive module.

[0060] In this configuration, the communication and operation ends are centrally located at the same axial end of the operating arm. The optical fiber of the fiber optic sensing unit 1-6 extends to this end through the capillary tube 1-1 inside the inner braided tube, forming the fiber optic connector 1-5. The flexible drive wire 1-7 extends axially along the inner wall of the inner braided tube to this end, forming the drive wire end. The fiber optic connector 1-5 is connected to the optical interface of the fiber optic demodulator 7-4 via a fiber optic patch cord, and the drive wire end is connected to the linear actuator of the drive module via a traction mechanism. This arrangement allows the signal transmission paths of the fiber optic sensing unit 1-6 and the flexible drive wire 1-7 to extend independently inside the operating arm, only exiting uniformly at the end, avoiding line crossing interference.

[0061] Specifically, when the optical fiber of the fiber optic sensing unit 1-6 is threaded through the capillary tube 1-1, it extends axially along the inner braided tube to the end of the operating arm, forming an optical fiber connector 1-5 with a standard connector, which is directly inserted into the input port of the fiber optic demodulator 7-4. The flexible drive wire 1-7, after passing through the inner braided tube mesh unit, extends axially along the inner wall to its end and is fixed to the ball screw slider of the drive module by a metal clamp. When the operating arm bends, the fiber optic demodulator 7-4 acquires the wavelength data of all FBGs in real time through the optical fiber connector 1-5 at the same end, and the drive module synchronously controls the displacement of multiple drive wires through the traction mechanism at the same end. This centralized connection structure integrates the physical interface of the sensing signal and the drive control signal into a single operating end, reducing the number of external cables, lowering signal transmission loss, and avoiding assembly errors caused by multi-end connections, ensuring the synchronization and stability of the strain signal and drive command.

[0062] As a preferred embodiment, the solution of this application is specifically implemented as follows:

[0063] The communication or operation ends of the fiber optic sensing unit 1-6 and the flexible drive wire 1-7 are located at the same end of the double-layer braided skeleton and are respectively connected to the fiber optic demodulator 7-4 and the drive module. Specifically, one end of the double-layer braided skeleton is provided with a connection port, from which the fiber optic connector 1-5 of the fiber optic sensing unit 1-6 and the connection end of the flexible drive wire 1-7 are led out. The fiber optic connector 1-5 is connected to the fiber optic demodulator 7-4 via a fiber optic connector, and the connection end of the flexible drive wire 1-7 is connected to the drive module via a mechanical connector. The fiber optic demodulator 7-4 is used to acquire and process the wavelength data of the fiber optic sensing unit 1-6, and the drive module is used to control the pulling motion of the flexible drive wire 1-7. Furthermore, the connection port adopts a waterproof and sealed structure to protect the internal fiber optic cable and drive wire from external environmental influences.

[0064] Through the above technical solution, this application achieves a centralized arrangement of the communication ends of the fiber optic sensing units 1-6 and the flexible drive wires 1-7, simplifying the structural design of the manipulator and improving the system integration. This reduces the number of external connection cables, lowering the risk of cable entanglement and interference during operation. Simultaneously, the centralized arrangement of the communication and manipulator ends facilitates maintenance and replacement, improving the system's reliability and maintainability. Furthermore, signal transmission between the fiber optic sensing units 1-6 and the drive module is more convenient, which is beneficial for achieving precise control and real-time shape sensing of the manipulator.

[0065] like Figure 5 and 6 As shown, this application further proposes that a silicone tube 5-1 is provided on the outer surface of the optical fiber sensing unit. The silicone tube 5-1 is tightly attached to the inner wall of the capillary 1-1, which serves to protect the optical fiber sensing unit 1-6 and fix the inside of the capillary 1-1, ensuring efficient strain transmission.

[0066] The silicone tube 5-1 is made of elastic material, and its inner diameter matches the outer diameter of the fiber optic sensing unit, while its outer diameter matches the inner diameter of the capillary tube 1-1. A tight fit is achieved through interference fit or casting. The axial length of the silicone tube 5-1 covers the entire length of the fiber optic sensing unit.

[0067] Specifically, when the manipulator arm bends and deforms, the strain generated by the double-layer braided skeleton is transmitted to the silicone tube 5-1 through the capillary tube 1-1. The elastic deformation of the silicone tube 5-1 uniformly applies the strain to the surface of the fiber optic sensing unit, avoiding measurement errors caused by localized stress concentration. During dynamic movement, the friction between the silicone tube 5-1 and the inner wall of the capillary tube 1-1 effectively suppresses axial sliding of the fiber optic sensing unit, preventing FBG position displacement. Experimental data shows that after fixing with the silicone tube 5-1, the strain transmission efficiency is significantly improved, and the error between the FBG wavelength drift and the theoretically calculated value is controlled within a preset range. The silicone tube 5-1 also isolates any potential mechanical vibration interference inside the capillary tube 1-1, and the fiber optic sensing unit remains stable after continuous bending fatigue testing.

[0068] As a preferred embodiment, the solution of this application is specifically implemented as follows:

[0069] A silicone tube 5-1 is cast onto the outer surface of the fiber optic sensing unit. The silicone tube 5-1 is tightly fitted to the inner wall of the capillary tube 1-1. The silicone tube 5-1 serves to protect the fiber optic sensing unit 1-6 and fix the internal structure of the capillary tube 1-1, ensuring efficient strain transmission.

[0070] Specifically, the fiber optic sensing unit is composed of optical fibers containing multiple fiber Bragg gratings. The fiber optic sensing unit 1-6 can be fixed inside the silicone tube 5-1 during the silicone casting process, with its sides tightly covered by silicone material. The fiber optic sensing unit encased in the silicone tube 5-1 is then inserted into the capillary tube 1-1. Due to the elasticity of the silicone material, the outer wall of the silicone tube 5-1 fits tightly against the inner wall of the capillary tube 1-1, eliminating gaps.

[0071] The silicone tube 5-1 protects the optical fiber, preventing it from being damaged by direct contact with the capillary tube 1-1. Simultaneously, the silicone tube 5-1 fixes the optical fiber in the center of the capillary tube 1-1, preventing it from shifting within the capillary tube. Furthermore, silicone material has excellent strain transfer properties; when the capillary tube 1-1 bends and deforms, the strain can be efficiently transferred to the optical fiber through the silicone tube 5-1, causing a corresponding wavelength change in the fiber Bragg grating, thereby achieving shape sensing.

[0072] Through the above technical solutions, this application improves the protection and stability of the fiber optic sensing unit while ensuring efficient strain transmission. Therefore, the fiber optic grating can accurately sense the bending deformation of the manipulator, improving the accuracy and reliability of shape sensing. Furthermore, the inclusion of the silicone tube 5-1 simplifies the installation process of the fiber optic sensing unit and improves production efficiency.

[0073] This application further proposes that at least three capillaries 1-1 with fiber optic sensing units are provided on the inner braided tube, and the capillaries 1-1 with fiber optic sensing units are evenly distributed in the circumferential direction.

[0074] The number of capillary tubes 1-1 is set to three or more, and their uniform circumferential distribution ensures that the fiber optic sensing units 1-6 form a symmetrical layout in the circumferential direction. For example, the three capillary tubes 1-1 are arranged around the axis of the inner braided tube at 120-degree intervals, ensuring that strain under different bending directions can be effectively detected. The uniform circumferential distribution further ensures that the strain transmission path is consistent in the circumferential direction, avoiding measurement errors caused by local stress concentration.

[0075] Specifically, when the manipulator bends, the capillaries 1-1 at different locations experience differentiated tensile or compressive strains due to their uniform circumferential distribution. The uniformly distributed capillaries 1-1 transmit the strain evenly to the internal fiber optic sensing unit 1-6, establishing a correspondence between the wavelength change of each FBG and the actual bending angle and direction. By simultaneously acquiring FBG data from the capillaries 1-1 equipped with the fiber optic sensing unit 1-6 using a demodulator, the host computer 7-5 can improve the accuracy of the bending angle and direction calculations based on the measured data. For example, three capillaries 1-1 form three detection points circumferentially, and the bending curvature and spatial orientation of the manipulator can be reconstructed using the triangulation principle.

[0076] As a preferred embodiment, the solution of this application is implemented as follows: At least three capillaries 1-1 with fiber optic sensing units are provided on the inner braided tube, and the capillaries 1-1 with fiber optic sensing units are evenly distributed circumferentially. Specifically, the inner braided tube uses six capillaries 1-1 spirally braided to form a tubular mesh structure, wherein three capillaries 1-1 have fiber optic sensing units 1-6 containing FBG inserted inside, and are tightly fitted to the inner wall of the capillaries 1-1.

[0077] Through the above technical solution, this application achieves omnidirectional sensing of the bending shape of a flexible manipulator. Since at least three capillaries 1-1 containing fiber optic sensing units 1-6 are circumferentially uniformly distributed, the bending state of the manipulator can be detected simultaneously from multiple directions, avoiding blind spots that may occur with single-direction detection. This layout enables the system to accurately capture the bending deformation of the manipulator in any direction, improving the accuracy and reliability of shape sensing. Simultaneously, the uniform distribution design also balances the strain transmission effect in various directions of the manipulator, ensuring the consistency and stability of shape sensing.

[0078] like Figure 1 As shown, this application further proposes that the fiber optic sensing unit is a single fiber with multiple FBGs distributed on it. The number of FBGs on the fiber is consistent with the number of joints on the manipulator, and the axial direction of all FBGs on the fiber corresponds one-to-one with the joint area on the manipulator. All FBGs are arranged sequentially from small to large according to the center wavelength range and do not overlap with each other.

[0079] The optical fiber employs a single-strand structure with multiple fiber gratings (FBGs) distributed axially. The axial position of each FBG is aligned with the joint area of ​​the manipulator arm. The center wavelength ranges of the FBGs are pre-designed to ensure non-overlapping wavelengths; for example, the wavelength spacing of each FBG is set to 5-10 nm, ensuring that the demodulator can quickly identify the corresponding grating number based on wavelength offset during data acquisition. The optical fiber is fixed by extending along the inner wall of the capillary 1-1 of the inner braided tube and tightly fitting it to the capillary 1-1 via a silicone tube 5-1, ensuring efficient strain transfer.

[0080] Specifically, when the manipulator bends, the deformation of each joint region is transmitted to the corresponding FBG (Fiber Optic Generative Gear) via the woven skeleton, causing a shift in its center wavelength. The fiber optic demodulator 7-4 acquires the spectral signal in the fiber in real time. By identifying the wavelength shift of each FBG and combining it with the pre-established wavelength-joint mapping relationship, the bending angle and direction of each joint are determined. Since all FBGs are integrated into a single fiber and their wavelengths do not overlap, the demodulator directly extracts the data of each joint independently through wavelength segmentation technology. For example, when the manipulator contains three joints, at least three fibers are evenly distributed circumferentially at each joint, and one FBG is set at each joint. All fibers are connected to a channel on the demodulator, and the demodulator processes three FBG signals at each channel, that is, the three channels process nine FBG signals. According to the wavelength range, the three FBG signals corresponding to each channel can be defined from small to large, that is, the three FBG wavelength data corresponding to each of the three joints can be identified and stored, realizing the structural reconstruction of the manipulator.

[0081] As a preferred embodiment, the solution of this application is specifically implemented as follows:

[0082] The fiber optic sensing unit is a single fiber optic cable with multiple fiber optic groups (FBGs). The number of FBGs on a single fiber optic cable corresponds to the number of joints on the manipulator, and the axial orientation of the FBGs on the fiber optic cable corresponds one-to-one with the joint areas on the manipulator. The FBGs on the optical fibers are arranged sequentially from smallest to largest according to their center wavelength range, and they do not overlap. This allows the fiber optic demodulator 7-4 to determine the grating number of the corresponding FBG based on the wavelength during data acquisition. For example, if an operating arm has three joints A, B, and C, three optical fibers A, B, and C are evenly distributed circumferentially along the axis of the operating arm. Fiber A carries FBGs A1, A2, and A3; fiber B carries FBGs B1, B2, and B3; and fiber C carries FBGs C1, C2, and C3. Therefore, the shape sensing elements for joint A are FBGs A1, B1, and C1; for joint B, they are FBGs A2, B2, and C2; and for joint C, they are FBGs A3, B3, and C3. Thus, when a joint of the operating arm bends, the corresponding FBG will experience strain, causing a change in its center wavelength, thereby achieving shape reconstruction of the operating arm.

[0083] The fiber optic demodulator 7-4 employs wavelength division multiplexing (WDM) technology, enabling simultaneous detection of center wavelength changes in multiple fiber optic groups (FBGs). Since the center wavelengths of each FBG do not overlap, the fiber optic demodulator 7-4 can determine which FBG has experienced strain based on the detected wavelength changes, thereby identifying which joint of the manipulator arm has bent.

[0084] Through the above technical solution, this application achieves simultaneous monitoring of the bending state of multiple joints in the manipulator. Since the number of fiber optic sensing elements (FBGs) matches the number of joints, and each FBG corresponds one-to-one with a joint, the location of the bending joint can be accurately pinpointed. The center wavelengths of the FBGs are arranged from smallest to largest and do not overlap, avoiding signal confusion caused by wavelength overlap and improving the accuracy of signal recognition. The fiber optic sensing unit uses a single optical fiber, simplifying the structure and facilitating integration inside the manipulator. Furthermore, the FBG sensor has advantages such as resistance to electromagnetic interference and high sensitivity, enabling stable operation in complex electromagnetic environments and making it suitable for scenarios such as medical surgery.

[0085] like Figure 6 As shown, based on the above scheme, when the axial spacing of each joint on the operating arm is set to be the same, this application further proposes that the fiber optic sensing unit is a fiber optic cable with multiple equally spaced FBG6-1 distributed on it. The FBGs on the fiber optic cable are axially distributed in the same number of joint areas of the operating arm. All FBGs on the fiber optic cable are arranged sequentially according to the center wavelength range from small to large and without overlapping, so that the fiber optic demodulator 7-4 can determine the grating number of the corresponding FBG according to the wavelength during data acquisition.

[0086] The fiber optic sensing unit is arranged with equal spacing FBG6-1, and the axial distance between adjacent FBGs remains constant. The center wavelength range of each FBG is preset as a continuous interval that does not overlap, and the wavelength order corresponds one-to-one with the axial position of the operating arm joint. The fiber optic demodulator 7-4 has a built-in wavelength-position mapping table, which can directly locate a specific FBG and its joint area by detecting the wavelength change and the corresponding wavelength interval.

[0087] Specifically, during the bending process of the manipulator arm, the equally spaced fiber optic girders (FBGs) experience wavelength drift due to uniform axial force. The strain transmission path length of adjacent FBGs is consistent, ensuring linear changes in the strain signal in each joint region. After acquiring real-time wavelength data, the fiber optic demodulator 7-4 sequentially matches the corresponding FBG numbers according to the preset wavelength range. Combining the calibration relationship between wavelength drift and bending angle, it quickly calculates the bending angle and direction of each joint. Since the wavelength ranges of all FBGs do not overlap, the demodulator does not need to perform complex signal separation processing. It can directly determine the position of each FBG by dividing the wavelength threshold, improving data acquisition efficiency and morphological reconstruction accuracy.

[0088] As a preferred embodiment, the solution of this application is implemented as follows: Twelve equally spaced fiber optic cables (FBGs) are distributed on a single optical fiber, with the axial position of each FBG corresponding one-to-one with the twelve joint regions of the manipulator. The optical fiber extends axially along the inner braided tube, and the center wavelength ranges of each FBG are arranged in ascending order and do not overlap. The fiber optic demodulator 7-4 detects the wavelength offset through a spectral analysis module and maps the wavelength change data to the bending angle of a specific joint according to a preset wavelength-joint correspondence table.

[0089] Through the above technical solution, this application avoids the signal crosstalk problem caused by the arrangement of multiple optical fibers by strictly corresponding the equally spaced FBG6-1 on a single optical fiber with the joint area of ​​the operating arm; by adopting the FBG arrangement with increasing wavelength range and non-overlapping FBG, the fiber demodulator 7-4 can quickly identify the deformation data of the corresponding joint based on the wavelength, which solves the positioning error problem caused by signal overlap of traditional external sensors, and realizes independent detection and high-precision calculation of the bending state of each joint of the operating arm.

[0090] like Figure 4 and 7As shown, this application further proposes that the flexible operating arm is provided with at least three flexible drive wires 1-7 corresponding to the end of each joint. One end of the flexible drive wires 1-7 located at the same joint is evenly distributed and fixed along the circumferential direction of the grid unit of the double-layer braided skeleton, and only one flexible drive wire 1-7 is provided in one grid unit. The other end of all the flexible drive wires 1-7 extends axially along the inner wall of the inner braided tube and passes through the operating arm to connect to the drive module. The drive module includes a drive unit and a controller 7-3. One drive unit is provided for each flexible drive wire 1-7, and all drive units are communicatively connected to the controller 7-3.

[0091] The drive unit can use a linear motor 7-1, with each flexible drive wire 1-7 corresponding to an independent motor. The controller 7-3 controls the driver 7-2 of the linear motor 7-1, thereby controlling the rotation of the motor to control the amount of tension of the drive wire, so that the joint where the drive wire is located can achieve bending motion.

[0092] Specifically, multiple flexible drive wires 1-7 are connected to the ends of multiple joints of the manipulator. Axial pulling of the drive wire connected to the end of the same joint can realize the bending movement of the joint. Axial pulling of the drive wire connected to the ends of different joints can realize the complex spatial movement of the multi-joint manipulator. One end of the drive wire is evenly distributed and fixed along the circumference of the mesh unit of the braided tube. Only a single drive wire is allowed to pass through the same mesh unit. The other end of the drive wire extends axially along the inner wall of the inner braided tube and passes through the proximal end 1-4 of the manipulator, and is connected to the corresponding linear motor 7-1. The linear motor 7-1 is connected to the controller 7-3 through the corresponding driver 7-2. The controller 7-3 is connected to the host computer 7-5.

[0093] As a preferred embodiment, the solution of this application is implemented as follows: Four flexible drive wires 1-7 are configured at the end of each joint of the flexible manipulator. One end of each drive wire is evenly distributed at 90-degree intervals along the circumferential direction of the grid units of the double-layer braided skeleton, with only one drive wire fixed within each grid unit. The other end of each drive wire extends axially along the inner wall of the inner braided tube to the proximal end 1-4 of the manipulator and is connected to four independent drive units. Each drive unit includes a micro servo motor and a traction mechanism. The four drive units are synchronously coordinated and controlled by a controller 7-3. When lateral bending of a joint is required, the controller 7-3 sends a pulse signal to the drive unit in the corresponding direction. The drive unit applies axial tension to the target drive wire through the traction mechanism, causing the joint to bend in the predetermined direction. When compound bending is required, the controller 7-3 simultaneously activates multiple drive units, and multi-degree-of-freedom spatial motion is achieved by adjusting the combination of tension of each drive wire.

[0094] Through the above technical solution, this application solves the problem of insufficient precision in multi-joint collaborative control of flexible manipulators. By achieving a precise match between the joint bending direction and the driving force through the circumferentially uniform distribution of drive wires and the correspondence with independent drive units, mutual interference between multiple drive wires during the traction process is avoided. Furthermore, by integrating the drive module with the manipulator body, the transmission delay of external control signals is reduced, improving the real-time performance and stability of motion control, and providing a reliable power execution foundation for delicate operations in complex surgical scenarios.

[0095] like Figure 7 As shown, this application further proposes a feedback control method for a braided flexible manipulator based on shape sensing using distributed fiber optic gratings (FBGs). The steps are as follows: Fiber optic connectors 1-5 of the fiber optic sensing unit are connected to the fiber optic demodulator 7-4; the fiber optic demodulator 7-4 establishes communication with the host computer 7-5 and collects wavelength data from the fiber optic sensing unit in real time, transmitting it to the host computer 7-5; the reference center wavelengths of each FBG in the manipulator's reference state are recorded; a calibration experimental platform is built; the actual bending angles and directions of each joint of the manipulator are accurately measured under different postures; the FBG wavelength change data collected by the fiber optic demodulator 7-4 in the corresponding state are recorded and analyzed to determine the relationship between the bending angles and directions of each joint of the manipulator and the FBG wavelengths. The mapping relationship of the wavelength change is stored in the host computer 7-5. During use, when the manipulator bends and deforms, the FBG is subjected to strain, and the center wavelength changes accordingly. After receiving the real-time wavelength data transmitted by the fiber optic demodulator 7-4, the host computer 7-5 calculates and analyzes the spatial posture of each joint of the manipulator accurately based on the pre-established mapping relationship and spatial coordinate transformation algorithm. By fusing the posture information of each joint, the overall three-dimensional shape of the manipulator is reconstructed. The fiber optic sensing unit 1-6 can detect the end-effector posture information and feed it back to the drive module. By comparing the actual posture with the target posture and combining the kinematic model of the manipulator, the pulling amount of the flexible drive wire 1-7 is controlled so that the actual posture of the end of the manipulator approaches the target posture.

[0096] Among them, the fiber optic demodulator 7-4 and the host computer 7-5 achieve synchronous data transmission through a communication protocol to ensure real-time updates of wavelength data; the calibration experimental platform fixes the joints of the operating arm with mechanical clamps, uses high-precision angle sensors to measure the actual bending angle and direction, and establishes a database that corresponds one-to-one with the wavelength change data collected by the fiber optic demodulator 7-4; the spatial coordinate transformation algorithm is based on the homogeneous transformation matrix to convert the attitude parameters of each joint in the local coordinate system into three-dimensional coordinates in the global coordinate system; the controller 7-3 of the drive module calculates the tension adjustment value of the flexible drive wire 1-7 through a PID algorithm based on the error signal output by the host computer 7-5, and the drive unit uses a stepper motor or pneumatic actuator to achieve axial displacement control.

[0097] Specifically, the fiber optic demodulator 7-4 collects wavelength data from all FBGs at a fixed sampling frequency, reflecting the strain distribution of each joint of the manipulator arm through wavelength offset. The host computer 7-5 matches the real-time wavelength data with the mapping relationship in the calibration database, calculates the bending angle and direction parameters joint by joint using a spatial coordinate transformation algorithm, and finally solves the tension of each drive wire through a kinematic model. The drive module adjusts the output of the corresponding drive unit according to the solution results, forming a closed-loop control loop. For example, when the error between the target pose and the reconstructed pose exceeds a threshold, the controller 7-3 reallocates the tension combination of each joint drive wire until the error converges to within the allowable range. This achieves real-time perception and precise control of the manipulator arm's shape, avoiding signal interference and delay problems caused by traditional external sensors.

[0098] As a preferred embodiment, the solution of this application is implemented as follows: When the manipulator is in use, fiber optic connectors 1-5 are first connected to the fiber optic demodulator 7-4, which establishes a communication protocol with the host computer 7-5 via an Ethernet interface. During the initial calibration phase, a high-precision laser displacement sensor measures the actual bending angle of each joint of the manipulator, and simultaneously records the FBG wavelength drift data output by the demodulator. The host computer 7-5 establishes a quadratic polynomial mapping model of the bending angle of each joint and the corresponding FBG wavelength change using the least squares method. In actual surgery, when the drive module pulls the drive wire according to the preset trajectory, the demodulator transmits wavelength data in real time at a preset sampling rate. The host computer 7-5 calls the pre-stored mapping model to calculate the bending angle of each joint and, combined with the Denavit-Hartenberg kinematic model, inversely calculates the three-dimensional pose of the manipulator.

[0099] Through the above technical solution, this application achieves full-length distributed shape perception and closed-loop motion control of the flexible manipulator, effectively solving the defects of traditional external sensors that are susceptible to electromagnetic interference and line-of-sight obstruction. By deeply integrating the fiber optic sensing units 1-6 with the drive system, the manipulator can correct motion deviations in real time in complex cavity environments, avoiding tissue damage caused by inaccurate shape perception, and significantly improving the operational accuracy and safety of minimally invasive surgical instruments.

[0100] As can be seen from the above embodiments, the braided flexible manipulator based on the distributed fiber optic grating of the present invention not only achieves shape perception and end-effector pose feedback control, but also has the advantages of high measurement accuracy, high reliability, rapid response, precise control and ingenious design. The efficient strain transfer of the fiber optic sensing units 1-6 makes it easier to improve the overall performance of the manipulator.

[0101] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

[0102] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A woven flexible manipulator based on distributed fiber Bragg grating for shape sensing, characterized in that: It includes a double-layer braided skeleton, which is composed of an inner braided tube and an outer braided tube tightly fitted together. The inner braided tube is a tubular mesh structure spirally woven with multiple strands of capillary tubes (1-1). An optical fiber sensing unit (1-6) containing FBG is inserted inside the capillary tube (1-1). A flexible drive wire (1-7) is provided in the double-layer braided skeleton.

2. The braided flexible manipulator based on distributed fiber Bragg grating for shape sensing according to claim 1, characterized in that: The outer braided tube is a tubular mesh structure made of spiral braided braided yarns (1-2). The inner braided tube and the outer braided tube are coaxially nested together, and the braiding angle of the outer braided tube is smaller than that of the inner braided tube.

3. The braided flexible manipulator based on distributed fiber Bragg grating for shape sensing according to claim 1, characterized in that: The fiber optic sensing unit (1-6) and the flexible drive wire (1-7) are located on the same side of the double-layer braided skeleton at one end outside the flexible manipulator.

4. The braided flexible manipulator based on distributed fiber Bragg grating for shape sensing according to claim 1, characterized in that: A silicone tube (5-1) is provided on the outer surface of the optical fiber sensing unit, and the silicone tube (5-1) is tightly attached to the inner wall of the capillary tube (1-1).

5. A woven flexible manipulator based on distributed fiber Bragg grating for shape sensing according to claim 4, characterized in that: At least three capillaries (1-1) with fiber optic sensing units are provided on the inner braided tube, and the capillaries (1-1) with fiber optic sensing units are evenly distributed circumferentially.

6. The braided flexible manipulator based on distributed fiber Bragg grating for shape sensing according to claim 5, characterized in that: The fiber optic sensing unit is an optical fiber with multiple FBGs distributed on it. The number of FBGs on the optical fiber is the same as the number of joints on the operating arm. All FBGs on the optical fiber are arranged in a one-to-one correspondence with the joint areas on the operating arm. All FBGs on the optical fiber are arranged sequentially from small to large according to the center wavelength range of the FBGs, and they do not overlap with each other.

7. A woven flexible manipulator based on distributed fiber Bragg grating for shape sensing according to claim 6, characterized in that: The fiber optic sensing unit is an optical fiber with multiple equally spaced FBGs (6-1). The FBGs on the optical fiber are axially distributed at the corresponding joint areas on the operating arm. All the FBGs on the optical fiber are arranged sequentially from small to large according to the center wavelength range of the FBGs, and they do not overlap with each other.

8. A woven flexible manipulator based on distributed fiber Bragg grating for shape sensing according to claim 1, characterized in that: The flexible manipulator arm is provided with at least three flexible drive wires (1-7) at the end of each joint. One end of the flexible drive wire (1-7) located at the same joint is evenly distributed and fixed along the circumferential direction of the grid unit of the double-layer braided skeleton, and only one flexible drive wire (1-7) is provided in one grid unit. The other end of all the flexible drive wires (1-7) extends axially along the inner wall of the inner braided tube and passes through the manipulator arm to connect to the drive module. The drive module includes a drive unit and a controller (7-3). Each flexible drive wire (1-7) is provided with a drive unit, and all drive units are communicatively connected to the controller (7-3).

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