An optical fiber intelligent flexible surgical robot

Abstract

The invention discloses an optical fiber intelligent flexible surgical robot, comprising an elastic skeleton, a Stewart platform type optical fiber grating sensor is fixed at one end of the elastic skeleton, and the Stewart platform type optical fiber grating sensor is connected to a clamp; a guide wire hole is arranged in the elastic skeleton, an elastic skeleton driving wire with one end fixed on the elastic skeleton is passed through the guide wire hole, a clamp driving wire with one end connected to the clamp is also arranged in the elastic skeleton, and the other ends of the elastic skeleton driving wire and the clamp driving wire are connected to a driving mechanism; the Stewart platform type optical fiber grating sensor comprises a moving platform connected to the clamp, a fixed platform connected to the elastic skeleton, and first to sixth branches connected between the moving platform and the fixed platform and inclinedly arranged with the moving platform and the fixed platform, wherein the first to sixth branches are hollow structures, optical fibers are passed through the first to sixth branches according to a certain sequence, optical fibers are arranged on the parts of the optical fibers located in the inner cavities of the first to sixth branches, and the optical fibers are connected to a demodulator through the guide wire hole.

Description

Technical Field

[0001] The present invention relates to the technical field of medical robots, and particularly to an optical fiber intelligent flexible surgical robot. Background Art

[0002] Natural orifice transluminal endoscopic surgery (NOTES) is a new type of minimally invasive surgery. It enters through orifices such as the oral cavity, nasal cavity, anus, vagina, etc., and enters the mediastinum, thoracic cavity, abdominal cavity or stomach through the natural cavities of the digestive tract, intestine and stomach for exploration, biopsy and various surgical operations. Compared with traditional surgery, NOTES has the advantages of less postoperative pain, shorter recovery time, no body surface scars, fewer postoperative complications, etc., and is more in line with the concept of modern ultra-minimally invasive treatment. However, traditional surgical instruments are rigid, with low flexibility, limited endoscopic vision, difficult to adapt to the complex human body environment, and lack of tactile feedback, which brings many difficulties to the operator. Therefore, endoscopic surgical robots have become a research hotspot.

[0003] Due to its special flexible structure, continuum robots have very strong compliance and motion dexterity, and are suitable for operating in the complex natural cavities of the human body. Currently, the common continuum robots mainly include concentric tube robots, origami robots, and spring robots, but they all have disadvantages such as poor lateral / axial stiffness and large size to varying degrees. In recent years, grooved-skeleton structure robots have been widely used in neurosurgery due to their small size and the ability to retain large lumens for instrument channels, but their control accuracy and working space need to be improved.

[0004] Currently, most sensors for monitoring surgical operating forces are electrical sensors, which are vulnerable to electromagnetic interference and have poor biocompatibility, making it difficult to adapt to the complex environment in the operating room. Fiber Bragg grating sensors have the advantages of small size, anti-electromagnetic interference, good biocompatibility, etc., and are widely used in medical scenarios. However, the existing fiber Bragg grating six-axis force sensors have poor isotropy and obvious non-linearity, and are not suitable for accurately sensing surgical operating forces. Summary of the Invention

[0005] The purpose of the present invention is to provide an optical fiber intelligent flexible surgical robot to achieve accurate sensing of operating forces during surgery.

[0006] To solve the above technical problems, the present invention provides a technical solution: an optical fiber intelligent flexible surgical robot, which includes an elastic skeleton. One end of the elastic skeleton is fixed with a Stewart platform type fiber optic grating sensor, and the Stewart platform type fiber optic grating sensor is connected with a clamp. A wire guiding hole is arranged inside the elastic skeleton, and an elastic skeleton driving wire fixed to the elastic skeleton at one end is threaded through the wire guiding hole. An end effector driving wire with one end connected to the clamp is also arranged inside the elastic skeleton. The other ends of the elastic skeleton driving wire and the end effector driving wire are connected to a driving mechanism. The Stewart platform type fiber optic grating sensor includes a moving platform connected to the clamp, a fixed platform connected to the elastic skeleton, and the first to sixth branches obliquely arranged between the moving platform and the fixed platform and connected to the moving platform and the fixed platform. The first to sixth branches are hollow structures, and optical fibers are threaded through the first to sixth branches in a certain order. Fiber Bragg gratings are arranged on the parts of the optical fibers located in the inner cavities of the first to sixth branches. The optical fibers pass through the wire guiding hole and are connected to a demodulator.

[0007] The driving mechanism controls the elastic skeleton to perform bending motion by pulling the elastic skeleton driving wire, and controls the clamp to perform clamping or releasing actions by pulling the end effector driving wire. When the elastic skeleton and the clamp perform the aforementioned motions, the clamp receives a force due to the influence of human tissues. Then, the force received by the clamp is transmitted to the first to sixth branches through the moving platform, causing the first to sixth branches to bend. As a result, the central wavelengths of the fiber Bragg gratings arranged in the first to sixth branches shift. The demodulator calculates the shifted central wavelengths, and thus obtains the six-dimensional force and moment information received by the clamp.

[0008] According to the above solution, the elastic skeleton includes a distal segment elastic skeleton near the clamp end and a proximal segment elastic skeleton far from the clamp end. The distal segment elastic skeleton includes a plurality of distal segment elastic deformation units connected end to end. The proximal segment elastic skeleton includes a plurality of proximal segment elastic deformation units connected end to end. The side walls of the distal segment elastic deformation units and the proximal segment elastic deformation units are both provided with a pair of elliptical notches symmetrically. The side walls of adjacent distal segment elastic deformation units are perpendicularly distributed, the side walls of adjacent proximal segment elastic deformation units are perpendicularly distributed, and the side walls of the distal segment elastic deformation units and the side walls of the proximal segment elastic deformation units are distributed at an angle of 45°.

[0009] According to the above solution, the side walls between adjacent distal segment elastic deformation units are connected by a distal segment wire guiding disc, and the side walls between adjacent proximal segment elastic deformation units are connected by a proximal segment wire guiding disc. The distal segment wire guiding disc is provided with a distal segment wire guiding hole, and the proximal segment wire guiding disc is provided with a distal segment wire guiding hole and a proximal segment wire guiding hole.

[0010] According to the above solution, a distal segment drive wire and a proximal segment drive wire are respectively threaded through the distal segment wire guide hole and the proximal segment wire guide hole. One end of the distal segment drive wire and the proximal segment drive wire is respectively connected to the end of the distal segment elastic framework close to the clamp and the end of the proximal segment elastic framework close to the clamp, and the other end of the distal segment drive wire and the proximal segment drive wire is connected to the drive mechanism.

[0011] According to the above solution, the drive mechanism includes linear motors corresponding to the number of elastic framework drive wires and clamp drive wires. A frame is arranged above the linear motors, and wire guide pulleys are arranged on the frame. One end of the elastic framework drive wires and the clamp drive wires passes through the wire guide pulleys and is connected to the linear motors.

[0012] According to the above solution, both ends of the branch are flexible ball hinges, and the middle part of the branch is a branch column. A first through hole for the optical fiber to pass through is arranged in the flexible ball hinge and the branch column, and a second through hole for suspending the optical fiber is arranged in the branch column. The second through hole divides the fiber Bragg grating in the branch into a first FBG located in the part of the first through hole and a second FBG located in the part of the second through hole, and a coating is plated on the first FBG; The branch column is also provided with an adhesive hole perpendicular to and communicating with the first through hole for injecting glue, and the adhesive hole is arranged on both sides of the second through hole.

[0013] According to the above solution, the number of both the distal segment drive wire and the proximal segment drive wire is 4, and the diameter of the proximal segment wire guide hole is larger than that of the proximal segment wire guide hole.

[0014] According to the above solution, the elastic framework and the elastic framework drive wire are made of nitinol alloy; The clamp is connected to the Stewart platform type fiber Bragg grating sensor by threads.

[0015] According to the above solution, the wire guide pulley consists of three-stage pulleys.

[0016] A six-dimensional force / torque sensing method realized by using the above optical fiber intelligent flexible surgical robot includes the following steps

[0017] S1. According to the relationship between the strain of the fiber Bragg grating and the internal force of the branch, combined with the material characteristic parameters and structural geometric parameters of the branch, obtain the relationship between the initial central wavelength offset ratio of the fiber Bragg grating and the strain and temperature increment, as well as the force / temperature solution matrix;

[0018] S2. Split the branch into several sub-parts, and add the flexibility matrices of each sub-part according to the principle of virtual work and the principle of superposition of deformations to obtain the overall flexibility matrix, and then obtain the force transfer matrix of the Stewart platform type fiber Bragg grating sensor;

[0019] S3. According to the force / temperature solution matrix, the force transfer matrix of the Stewart platform fiber Bragg grating sensor, and the sensitivity matrix of the sensor, combined with the force on the elastic unit, the central wavelength shift of each fiber Bragg grating, and the temperature change, the magnitudes of the six-dimensional force / moment received by the Stewart platform fiber Bragg grating sensor can be obtained through decoupling calculation.

[0020] The beneficial effects of the present invention are as follows:

[0021] 1. By adopting a fiber Bragg grating sensor with a special structural form, accurate perception of the operating force during the surgical process is achieved.

[0022] 2. The elliptical notches of adjacent elastic deformation units in different segments of the elastic skeleton are perpendicularly distributed to make the elastic skeleton suitable for the control of multiple driving wires.

[0023] 3. The elliptical notches of the distal segment elastic deformation unit and the proximal segment elastic deformation unit are staggered at 45°, reducing the coupling interference between the distal segment wire guide disk and the proximal segment wire guide disk.

[0024] 4. The elastic skeleton and the elastic skeleton driving wire are made of nitinol alloy, improving the biocompatibility of the device. Description of the Drawings

[0025] Figure 1 is a schematic structural diagram of the fiber optic intelligent flexible surgical robot according to an embodiment of the present invention;

[0026] Figure 2 is a schematic structural diagram of the driving mechanism according to an embodiment of the present invention;

[0027] Figure 3 is a schematic structural diagram of the Stewart platform fiber Bragg grating sensor according to an embodiment of the present invention;

[0028] Figure 4 is a schematic diagram of the branch structure of the Stewart platform fiber Bragg grating sensor according to an embodiment of the present invention;

[0029] Figure 5 is a schematic diagram of the force on the elastic skeleton tube wall according to an embodiment of the present invention;

[0030] Figure 6 is an analysis diagram of the force on a single elastic deformation unit and a schematic diagram of the winch equation principle according to an embodiment of the present invention;

[0031] Figure 7 is a schematic diagram of the principle of the iterative method of the orthogonally arranged elastic skeleton according to an embodiment of the present invention;

[0032] Figure 8 is a flow chart of the iterative process of the orthogonally arranged elastic skeleton according to an embodiment of the present invention;

[0033] Figure 9 Schematic diagram of the establishment method of the coordinate system of the orthogonal arrangement elastic skeleton kinematic model according to an embodiment of the present invention;

[0034] Figure 10 Schematic diagram of the branch splitting according to an embodiment of the present invention.

[0035] In the figure: 101 - clamp, 102 - Stewart platform type fiber Bragg grating sensor, 103 - distal segment elastic skeleton, 104 - proximal segment elastic skeleton, 105 - distal segment wire guiding disc, 106 - proximal segment wire guiding disc, 107 - clamp driving wire, 108 - distal segment driving wire, 109 - proximal segment driving wire, 201 - linear motor, 202 - frame, 203 - wire guiding pulley, 204 - elastic skeleton driving wire, 301 - moving platform, 302 - optical fiber, 303 - fixed platform, 304 - first branch, 305 - second branch, 306 - third branch, 307 - fourth branch, 308 - fifth branch, 309 - sixth branch, 401 - flexible ball hinge, 402 - glue hole, 403 - branch column, 404 - fiber Bragg grating. Specific embodiments

[0036] To make the objectives, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present disclosure. Apparently, the described embodiments are some but not all of the embodiments of the present disclosure. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present disclosure without creative efforts shall fall within the scope of protection of the present disclosure.

[0037] See Figures 1 to 4, an optical fiber intelligent flexible surgical robot, comprising an elastic skeleton, a Stewart platform type optical fiber Bragg grating sensor 102 is fixed at one end of the elastic skeleton, and the Stewart platform type optical fiber Bragg grating sensor 102 is connected to a clamp 101; a guide wire hole is arranged in the elastic skeleton, and an elastic skeleton driving wire 204 with one end fixed on the elastic skeleton is passed through the guide wire hole, and a clamp driving wire 107 with one end connected to the clamp 101 is also arranged in the elastic skeleton, and the other ends of the elastic skeleton driving wire 204 and the clamp driving wire 107 are connected to a driving mechanism; the Stewart platform type optical fiber Bragg grating sensor 102 includes a moving platform 301 connected to the clamp 101, a fixed platform 303 connected to the elastic frame, and a first branch 304, a second branch 305, a third branch 306, a fourth branch 307, a fifth branch 308, and a sixth branch 309 connected between the moving platform 301 and the fixed platform 303 and inclined to the moving platform 301 and the fixed platform 303, wherein the first to sixth branches are hollow structures, and the first to sixth branches are penetrated with optical fibers 302 in a certain order (in this embodiment, the optical fiber 302 penetrates from one side of the fixed platform 303 and passes out from one side of the fixed platform 303. For a specific penetration method, see Figure 3 ), the portion of the optical fiber 302 located in the first to sixth branch cavities is provided with a fiber grating 404, and the optical fiber 302 passes through the guide wire hole and is connected to a demodulator;

[0038] The driving mechanism controls the elastic skeleton to perform bending movement by pulling the elastic skeleton driving wire 204, and controls the clamp 101 to clamp or release by pulling the clamp driving wire 107; when the elastic skeleton and the clamp 101 perform the aforementioned movement, the clamp 101 receives a force due to the influence of human tissue, and then the force applied to the clamp 101 is transmitted to the first to sixth branches via the moving platform 301, causing the first to sixth branches to bend, and then the central wavelength of the fiber grating 304 set in the first to sixth branches is shifted, and the shifted central wavelength is resolved by a demodulator to obtain the six-dimensional force and torque information applied to the clamp 101.

[0039] Furthermore, the elastic skeleton includes a distal segment elastic skeleton 103 near one end of the clamp 101 and a proximal segment elastic skeleton 104 away from one end of the clamp 101, the distal segment elastic skeleton 103 includes a plurality of distal segment elastic deformation units connected end to end, the proximal segment elastic skeleton 104 includes a plurality of proximal segment elastic deformation units connected end to end, the sides of the distal segment elastic deformation unit and the proximal segment elastic deformation unit are both tube walls symmetrically provided with a pair of elliptical notches, the tube walls of adjacent distal segment elastic deformation units are perpendicular to each other, the tube walls of adjacent proximal segment elastic deformation units are perpendicular to each other, and the tube walls of the distal segment elastic deformation unit and the tube walls of the proximal segment elastic deformation unit are distributed at an angle of 45°.

[0040] Further, the tube walls of adjacent distal - segment elastic - deformation units are connected by a distal - segment wire guide disk 105, and the tube walls of adjacent proximal - segment elastic - deformation units are connected by a proximal - segment wire guide disk 106; the distal - segment wire guide disk 105 is provided with distal - segment wire holes, and the proximal - segment wire guide disk 106 is provided with distal - segment wire holes and proximal - segment wire holes; through - holes for passing a clamp driving wire 107 are provided on both the proximal - segment wire guide disk 106 and the distal - segment wire guide disk 105; in this embodiment, the elastic framework is made of a nickel - titanium alloy tube. The tube - wall material is removed by laser according to elliptical notches on the elastic framework by a laser - cutting method to form elliptical notches, and then a wire - guide - disk opening is cut at the position where the wire guide disk is designed to be installed. The wire guide disk is installed at the wire - guide - disk opening, and then the wire guide disk is fixed by glue; the elliptical notch shape has a large movement range and high movement accuracy while ensuring good stiffness characteristics and good axial - load characteristics.

[0041] Further, a distal - segment driving wire 108 and a proximal - segment driving wire 109 are respectively inserted into the distal - segment wire hole and the proximal - segment wire hole. One ends of the distal - segment driving wire 108 and the proximal - segment driving wire 109 are respectively connected to the end of the distal - segment elastic framework 103 close to the clamp 101 and the end of the proximal - segment elastic framework 104 close to the clamp 101 by spot welding, and the other ends of the distal - segment driving wire 108 and the proximal - segment driving wire 109 are connected to a driving mechanism.

[0042] Further, the driving mechanism includes linear motors 201 corresponding to the number of elastic - framework driving wires 204 and clamp driving wires 107. A frame 202 is arranged above the linear motors 201, and wire guide pulleys 203 are arranged on the frame 202. One ends of the elastic - framework driving wires 204 and the clamp driving wires 107 pass through the wire guide pulley 204 and are connected to the linear motors.

[0043] Further, both ends of the branch are flexible ball joints 401, and the middle part of the branch is a branch column 403. A first through - hole for passing an optical fiber 302 is arranged in the flexible ball joint 401 and the branch column 403. A second through - hole for suspending the optical fiber 302 is arranged in the branch column 403. The second through - hole divides the fiber grating 404 in the branch into a first FBG located in the first - through - hole part and a second FBG located in the second - through - hole part, and a coating is plated on the first FBG; the branch column 403 is further provided with an adhesive hole 402 perpendicular to and communicating with the first through - hole for injecting glue, and the adhesive hole 402 is arranged on both sides of the second through - hole.

[0044] Further, the number of both the distal - segment driving wire 108 and the proximal - segment driving wire 109 is 4, and the diameter of the proximal - segment wire hole is larger than that of the proximal - segment wire hole.

[0045] Further, the clamp 101 adopts a parallelogram mechanism.

[0046] Furthermore, the elastic framework and the elastic framework driving wire 204 are made of nitinol alloy.

[0047] Furthermore, the wire pulley 203 consists of three-stage pulleys. The wire pulley 203 is used to guide and converge the elastic framework driving wire 204 so that the size of the elastic framework driving wire 204 corresponds to that of the wire spool.

[0048] Furthermore, the clamp 101 is connected to the Stewart platform type fiber Bragg grating sensor 102 by threads.

[0049] Furthermore, the fixed platform 303, the moving platform 301 and the branches of the Stewart platform type fiber Bragg grating sensor 102 are all made of elastic materials.

[0050] Furthermore, the fiber Bragg grating 404 arranged inside the Stewart platform type fiber Bragg grating sensor 102 is a fiber Bragg grating.

[0051] The process of controlling the attitude of the elastic framework by controlling the elastic framework driving wire 204 is as follows:

[0052] See Figure 5 , first analyze the stiffness characteristics of the elliptical flexible hinge formed by cutting the side walls of the elastic deformation units (including the distal segment elastic deformation unit and the proximal segment elastic deformation unit),

[0053] x h = F / K (1)

[0054] where F is the force and moment on the elliptical flexible hinge, x h is the corresponding deformation, and K is the stiffness of the flexible hinge;

[0055] The rotational stiffness of the elliptical flexible hinge can be obtained by the microelement method:

[0056]

[0057]

[0058] In the formula, s = a y / t. Where K is the rotational stiffness of the elliptical flexible hinge, w is the thickness of the nitinol alloy tube wall, t is the minimum width of the elliptical notch, a x , a y are the lengths of the major and minor semi-axes of the ellipse respectively; E is the elastic modulus of the nitinol alloy material.

[0059] Analyze the deformation of a single flexible deformation unit according to the winch equation as follows, and the principle is as Figure 6 shown:

[0060]

[0061]

[0062] Among them, μ is the friction coefficient, θ is the bending angle of the i-th elastic deformation unit, and β is the angle between F i+1 and T i .

[0063] The input force Fi of the i-th elastic deformation unit can be obtained through Equation (7). i and the input force Fi+1 of the (i + 1)-th unit i+1 .

[0064] The torque on the elliptical flexure hinge can be expressed as:

[0065] M yi = |F i ·r| (5)

[0066] where r is the vector from the central axis of the continuum manipulator to the action point of the driving wire;

[0067] The deformation angle of a single elliptical flexure hinge is as follows:

[0068] θ i = M yi / 2K (6)

[0069] After deriving the relationship between the deformation angle of a single flexible unit and the input forces of a driving wire on two adjacent elastic deformation units, and performing iteration on it, the deformation angles of all units and the total bending angle of the elastic framework can be obtained.

[0070] The principle of obtaining the overall deformation of the continuum manipulator is as follows, and the schematic diagram is as shown in Figure 7 : First, mechanical modeling is performed on the first flexible unit, and the output force of the first flexible unit is used as the input force of the second flexible unit. The bending angle of the second flexible unit is obtained through the above process. Repeat the above process until all flexible units are traversed. The flow chart of the iteration process is as shown in Figure 8 .

[0071] Based on the above mechanical model analysis process, the dynamic model is summarized as:

[0072] [θ1, θ2,..., θ n = f(F input ) (7)

[0073] Based on the piecewise constant curvature assumption, the kinematic model of the continuum robot is established:

[0074] Analyze the kinematic description of each elastic deformation unit separately, and then obtain the pose of the end through iteration. Fix the local coordinate system of each elastic deformation unit on the upper surface of the wire guide disc at the lower part of each elastic deformation unit, O i is located at the center of the upper surface of each wire guide disc, z i axis is perpendicular to the wire guide disc plane and upward, y i direction is perpendicular to the elliptical flexible hinge and outward, x i direction is obtained by the right-hand rule. The coordinate system establishment method of each unit is as Figure 9 shown.

[0075] Then from the i-th coordinate system to the i+1-th coordinate system can be obtained by the following transformation: first translate along the z i axis by then rotate around the x i axis after translation by θ i , and finally rotate around the newly obtained z i+1 axis by α i to obtain the i+1-th coordinate system

[0076] Then the homogeneous transformation matrix is as follows:

[0077]

[0078] The homogeneous transformation matrix from the base coordinate system to the end coordinate of the continuum manipulator is constructed as follows:

[0079]

[0080] After obtaining the transformation matrix, the position coordinates of the N-th elastic deformation unit can be obtained through iteration.

[0081] Combining the above dynamic model and kinematic model, the end pose of the robot can be obtained according to the driving force input by the driving wire.

[0082] The process of decoupling the six-dimensional force / torque information received by the Stewart platform type fiber optic grating sensor according to the central wavelength drift amount information of the fiber optic grating 404 is as follows:

[0083] First, analyze a single branch of the sensor. The cavity inside the branch divides the fiber optic grating into two parts, namely the first FBG and the second FBG.

[0084] Relationship between strain and internal force of the first FBG:

[0085]

[0086]

[0087] Relationship between strain and internal force of the second FBG:

[0088]

[0089] Among them, ε 1a and ε 2a represent the strains of the first FBG and the second FBG respectively, f represents the internal force of the branch, represents the strain elastic modulus of the glue, E b 、E g 、E f represent the elastic moduli of the branch, glue, and optical fiber respectively, A1 and A2 represent the areas of cross-sections A and B in Figure 4 respectively, and A3 represents the cross-sectional area of the glue;

[0090] Then, by combining (10) and (11), we can obtain:

[0091]

[0092] Combined with the sensing principle of FBG, the relationship between the response of each FBG and the deformation and temperature caused by force / moment can be described as:

[0093] Δλ i / λ i =k1ε i +k2ΔT

[0094] =(1 - ρ e )ε i +(α + ξ)ΔT (13)

[0095] Among them, λ i and Δλ i represent the initial central wavelength value and the central wavelength shift of the i-th FBG unit respectively. ΔT represents the temperature increment. k1 and k2 are the strain coefficient and the temperature coefficient respectively. ξ represents the strain optical coefficient. α represents the thermal expansion coefficient of the optical fiber. ρ e represents the elasto-optic coefficient of the optical fiber.

[0096] Substituting (13) into (12), we can solve for the internal force f i of a single branch and the temperature increment ΔT respectively.

[0097] It can be expressed in the following form:

[0098]

[0099] Among them, P i represents the solution matrix.

[0100] Taking the moving platform 301 as the research object, according to the screw theory, the force balance equation can be established as follows:

[0101]

[0102] In the formula: F w = [f w , m w T , representing the resultant external force vector acting on the moving platform 301.

[0103] f w = [f wx , f wy , f wz T , representing the force vector acting on the moving platform 301.

[0104] m w = [m wx , m wy , m wz T , representing the moment acting on the moving platform 301.

[0105] f i , representing the magnitude of the axial force on the i-th branch.

[0106] $ i = [S i , S 0i T , the axial line vector of the i-th branch.

[0107] Then,

[0108] F w = Gf (16)

[0109] Where: f = [f1, f2, f3, f4, f5, f6] T is the vector composed of the reaction forces of the six branches, and G is the force mapping matrix of the sensor.

[0110] The force mapping matrix G of the sensor can be obtained by performing a flexibility analysis on the sensor.

[0111] See Figure 10 , the branch is split into several sub-parts, and according to the principle of virtual work and the principle of superposition of deformations, the flexibility matrices of each sub-part are added to obtain the overall flexibility matrix. The general expression form is as follows:

[0112] C j = T i j C i (T i j ) T ​​​​(17)

[0113]

[0114]

[0115]

[0116]

[0117] where C j represents the flexibility matrix in the reference coordinate system i. represents the transformation matrix from the reference coordinate system i to the coordinate system j. represents the rotation matrix of the reference coordinate system i with respect to the coordinate system j. represents the position coordinates of the reference coordinate system i in the coordinate system j. represents the skew-symmetric matrix of the position coordinates. k is the sign coefficient, k = -1 for the slotted part and k = 1 for other parts.

[0118] After the transformation and superposition of the flexibility matrix, the force transfer matrix G of the sensor can be obtained.

[0119] In summary, the relationship between the wavelength shift of the fiber Bragg grating and the six-dimensional force / torque is expressed as follows:

[0120]

[0121] where [P] 6×6 is the force / temperature solution matrix, is the inverse matrix of the force transfer matrix, [S] 6×6 is called the sensitivity matrix of the sensor.

[0122] By the above method, when the sensor is subjected to six-dimensional force / torque, the information of the force / torque and the central wavelength shift of the six fiber Bragg gratings can be obtained, and the magnitude of the six-dimensional force / torque can be obtained through decoupling calculation.

[0123] The technical effects of the present invention are:

[0124] (1) The slotted-frame continuum robot structure based on elliptical hinges is adopted, which has a large motion range and high motion accuracy while ensuring good stiffness characteristics and good axial load characteristics. The two-section structure enables the continuum robot to have a high degree of freedom, a wider reachable workspace and higher motion dexterity, and at the same time has the advantages of small size, few parts, simple assembly process, small bending friction in the continuum, and a large lumen that can be reserved for the instrument channel.

[0125] (2) By integrating fiber Bragg grating sensing technology, a Stewart platform-based fiber Bragg grating six-axis force sensor is proposed, which realizes an integrated integration with the robot body and has the advantages of anti-electromagnetic interference, biocompatibility, small size, and high sensitivity.

[0126] (3) The sensor branch uses a flexible spherical hinge instead of a traditional hinge, eliminating the clearance and motion backlash in the traditional rigid hinge, and having the advantages of frictionless, wear-free, no need for lubrication, and integrally formed processing, with a high resolution. The optical fiber and the elastic structure are arranged in parallel, reducing the risk of grating chirping. The branch adopts an inner cavity structure, which can achieve temperature decoupling.

[0127] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. An optical fiber intelligent flexible surgical robot, characterized in that: It includes an elastic skeleton, with a Stewart platform type fiber Bragg grating sensor fixed at one end of the elastic skeleton. The Stewart platform type fiber Bragg grating sensor is connected with a clamp; a wire guiding hole is arranged inside the elastic skeleton, and an elastic skeleton driving wire fixed to the elastic skeleton at one end is threaded through the wire guiding hole. A clamp driving wire with one end connected to the clamp is also arranged inside the elastic skeleton. The other ends of the elastic skeleton driving wire and the clamp driving wire are connected to a driving mechanism; the Stewart platform type fiber Bragg grating sensor includes a moving platform connected to the clamp, a fixed platform connected to the elastic skeleton, and the first to sixth branches inclinedly arranged between the moving platform and the fixed platform. Among them, the first to sixth branches are hollow structures, and optical fibers are threaded through the first to sixth branches in a certain order. Fiber Bragg gratings are arranged on the parts of the optical fibers located in the inner cavities of the first to sixth branches. The optical fibers pass through the wire guiding hole and are connected to a demodulator; The driving mechanism controls the elastic skeleton to perform bending motion by pulling the elastic skeleton driving wire, and controls the clamp to perform clamping or releasing actions by pulling the clamp driving wire; when the elastic skeleton and the clamp perform the aforesaid motions, the clamp receives acting forces due to the influence of human tissues. Then, the acting forces received by the clamp are transmitted to the first to sixth branches through the moving platform, causing the first to sixth branches to bend. As a result, the central wavelengths of the fiber Bragg gratings arranged in the first to sixth branches shift. The demodulator calculates the shifted central wavelengths, and then obtains the six-dimensional force and moment information received by the clamp; The elastic skeleton includes a distal segment elastic skeleton and a proximal segment elastic skeleton. The distal segment elastic skeleton includes several distal segment elastic deformation units, and the proximal segment elastic skeleton includes several proximal segment elastic deformation units; the side walls of the distal segment elastic deformation units and the proximal segment elastic deformation units are both tubes with a pair of elliptical notches symmetrically opened. The tube walls of adjacent distal segment elastic deformation units are perpendicularly distributed, the tube walls of adjacent proximal segment elastic deformation units are perpendicularly distributed, and the tube walls of the distal segment elastic deformation units and the tube walls of the proximal segment elastic deformation units are distributed at an angle of 45°; The tube walls between adjacent distal segment elastic deformation units are connected by a distal segment wire guiding disc, and the tube walls between adjacent proximal segment elastic deformation units are connected by a proximal segment wire guiding disc.

2. The fiber optic intelligent flexible surgical robot according to claim 1, wherein: The distal segment wire guiding disc is provided with a distal segment wire guiding hole, and the proximal segment wire guiding disc is provided with a distal segment wire guiding hole and a proximal segment wire guiding hole.

3. The fiber optic intelligent flexible surgical robot according to claim 2, wherein: A distal segment driving wire and a proximal segment driving wire are respectively threaded through the distal segment wire guiding hole and the proximal segment wire guiding hole. One ends of the distal segment driving wire and the proximal segment driving wire are respectively connected to the end of the distal segment elastic skeleton close to the clamp and the end of the proximal segment elastic skeleton close to the clamp. The other ends of the distal segment driving wire and the proximal segment driving wire are connected to the driving mechanism.

4. The fiber optic intelligent flexible surgical robot according to claim 1, wherein: The driving mechanism includes linear motors corresponding to the number of the elastic skeleton driving wire and the clamp driving wire. A frame is arranged above the linear motors, and wire guiding pulleys are arranged on the frame. One ends of the elastic skeleton driving wire and the clamp driving wire pass through the wire guiding pulleys and are connected to the linear motors.

5. The fiber optic intelligent flexible surgical robot according to claim 1, wherein: Both ends of the branch are flexible ball hinges, and the middle part of the branch is a branch column. A first through hole for the optical fiber to pass through is provided in the flexible ball hinge and the branch column. A second through hole for suspending the optical fiber is provided in the branch column. The second through hole divides the fiber grating in the branch into a first FBG located in the first through hole part and a second FBG located in the second through hole part, and a coating is plated on the first FBG. The branch column is also provided with an adhesive hole perpendicular to and communicating with the first through hole for injecting glue, and the adhesive hole is provided on both sides of the second through hole.

6. The fiber optic intelligent flexible surgical robot according to claim 3, wherein: The number of the distal segment drive wires and the proximal segment drive wires is 4, and the diameter of the proximal segment guide wire hole is larger than that of the proximal segment guide wire hole.

7. The fiber optic intelligent flexible surgical robot according to claim 1, characterized in that: The elastic skeleton and the elastic skeleton drive wire are made of nitinol alloy; the clamp is connected to the Stewart platform type fiber grating sensor by threads.

8. The optical fiber intelligent flexible surgical robot according to claim 4, characterized in that: The guide wire pulley consists of three-stage pulleys.

9. A six-dimensional force / torque sensing method implemented by the fiber optic intelligent flexible surgical robot according to any one of claims 1-8, characterized in that: It includes the following steps S1. According to the relationship between the strain of the fiber grating and the internal force of the branch, combined with the material characteristic parameters and structural geometric parameters of the branch, obtain the relationship between the initial center wavelength offset ratio of the fiber grating and the strain and temperature increment, as well as the force / temperature solution matrix. S2. Split the branch into several sub-parts, and add the flexibility matrices of each sub-part according to the principle of virtual work and the principle of superposition of deformations to obtain the overall flexibility matrix, and then obtain the force transfer matrix of the Stewart platform type fiber grating sensor. S3. According to the force / temperature solution matrix, the force transfer matrix of the Stewart platform type fiber grating sensor, and the sensitivity matrix of the sensor, combined with the force on the elastic unit, the center wavelength offset of each fiber grating, and the temperature change, the six-dimensional force / moment received by the Stewart platform type fiber grating sensor can be obtained through decoupling calculation.

Images