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CN-121971228-A - High-sensitivity ophthalmic microsurgery forceps force sensing system and calibration method

CN121971228ACN 121971228 ACN121971228 ACN 121971228ACN-121971228-A

Abstract

The invention discloses a high-sensitivity ophthalmic microsurgery forceps force sensing system and a calibration method, wherein the system comprises surgical forceps and a matched tube, a fixed outer tube is sleeved outside the matched tube, the matched tube can axially move and rotationally move in the fixed outer tube, when the matched tube axially moves in the fixed outer tube, the fixed outer tube can be abutted or not abutted with the surgical forceps to enable the surgical forceps to be closed or opened, a hollow structure groove is formed in the position, close to the surgical forceps, of the fixed outer tube, an optical fiber is arranged on the fixed outer tube, the optical fiber is provided with a grating with a wavelength change region, the grating corresponds to the hollow structure groove, and the grating can generate corresponding wavelength change along with the deformation of the hollow structure groove. The invention adds the hollow structure groove at the tail end part of the fixed outer tube, so that the force sensing sensitivity is effectively enhanced, and the invention concentrates the calculation model at the contact part of the tweezers and the force sensor, can adapt to the change of algebraic relation caused by the change of the physical model, and reduces the error in the transmission process.

Inventors

  • ZHANG HE

Assignees

  • 智视觉医疗机器人(哈尔滨)有限公司

Dates

Publication Date
20260505
Application Date
20260129

Claims (10)

  1. 1. The ophthalmic microsurgery forceps force sensing system with the high sensitivity is characterized by comprising forceps and a matched tube fixedly connected with the forceps, wherein a fixed outer tube is sleeved outside the matched tube, the matched tube can axially move and rotationally move in the fixed outer tube, when the matched tube axially moves in the fixed outer tube, the fixed outer tube can be abutted or not abutted to the forceps so as to enable the forceps to be closed or opened, a hollow structure groove is formed in the position, close to the forceps, of the fixed outer tube, an optical fiber is arranged on the fixed outer tube, the optical fiber is provided with a grating with a wavelength change area, the grating corresponds to the hollow structure groove, and the grating can generate corresponding wavelength change along with the deformation of the hollow structure groove.
  2. 2. The high sensitivity ophthalmic microsurgical forceps force sensing system of claim 1, wherein the optical fiber is affixed to the stationary outer tube.
  3. 3. The high sensitivity ophthalmic microsurgical forceps force sensing system of claim 1, wherein the stationary outer tube and hollow structural slots are of unitary construction.
  4. 4. The high-sensitivity ophthalmic microsurgery forceps force sensing system according to claim 1, wherein the fixed outer tube and the hollow-out structure groove are both made of nickel-titanium alloy.
  5. 5. The high-sensitivity ophthalmic microsurgery forceps force sensing system according to claim 1, wherein the hollowed-out structural groove is formed by femtosecond laser cutting.
  6. 6. A high-sensitivity ophthalmic microsurgery forceps force sensing calibration method, characterized in that the high-sensitivity ophthalmic microsurgery forceps force sensing system according to any one of claims 1-5 is used, the method comprising the following steps: step 1, force-bearing decomposition of a force sensing system of the microsurgery forceps, namely, when the forceps are in a state of not receiving external force, in order to clamp the forceps, the ends of the forceps can generate relative axial movement on the fixed outer tube, the axial movement can generate force acting on the fixed outer tube, and the force is decomposed into axial force along the axial direction of the fixed outer tube And radial forces perpendicular to the axial direction of the fixed outer tube The method comprises 、 Respectively represent the axial force and the radial force applied by the surgical forceps to the FBG force sensor under the condition of no external force, the two forces of the part are irrelevant to the outside, and the two radial forces only apply to the FBG force sensor when the surgical forceps are naturally closed The mutual offset and neglect; step 2, establishing a mechanical relationship under the action of axial force, namely when the surgical forceps are only subjected to external axial force When in action, axial force is applied to the FBG force sensor Analyzing two states of the forceps under the action of no external force and the action of axial external force to obtain two equations based on the hyperstatic structure: Wherein the method comprises the steps of And Young's moduli of the forceps and the FBG force sensor respectively; And Cross-sectional areas of forceps and FBG force sensor respectively; And The initial lengths of the forceps and the FBG force sensor are respectively obtained by taking the difference of the two equations: further simplifying and obtaining: Of the formula (I) Representing external axial forces When the forceps are in operation, the force transmitted to the FBG force sensor is changed; step 3, establishing a mechanical relationship under the action of radial force, namely when the surgical forceps are only subjected to external radial force When the deflection y of the surgical forceps is equal to the deflection of the FBG force sensor, the following equation is obtained: Wherein, the Is a constant parameter related to the material and cross-sectional shape of the FBG force sensor and forceps only; Is composed of Radial force generated at the end of the FBG force sensor; And 4, calculating the wavelength drift amount of the FBG sensor, wherein the sensing principle of the fiber Bragg grating FBG is that the peak wavelength of the fiber Bragg grating FBG generates wavelength drift when the strain changes, Calculating the drift amount caused by strain generated under the action of different external forces: Wherein, the Is the distance of the FBG force sensor to the neutral plane, Is the moment of inertia of the FBG force sensor, Is the distance from the tip of the forceps to the center of the flexible hinge, wherein Is a constant related to the inherent physical characteristics of the FBG force sensor, Representing the strain offset of the FBG force sensor; and 5, establishing a functional relation between the wavelength offset of the FBG force sensor and the corresponding external force, thereby establishing a measurement model of the force sensing system and realizing calibration of the FBG force sensor.
  7. 7. The high-sensitivity ophthalmic microsurgery forceps force sensing calibration method of claim 6, wherein the FBG force sensor is an optical fiber and a grating arranged on a fixed outer tube.
  8. 8. The high-sensitivity ophthalmic microsurgery forceps force sensing calibration method of claim 6, wherein the FBG force sensor is a three-degree-of-freedom force sensor.
  9. 9. The method for calibrating force sensing of high-sensitivity ophthalmic microsurgery forceps according to claim 6, wherein in the step 5, a weight hanging method or a precision force measuring instrument method is adopted to establish a functional relationship between the FBG force sensor and the corresponding external force.
  10. 10. The high-sensitivity ophthalmic microsurgery forceps force sensing calibration method according to claim 9 is characterized in that the weight hanging method comprises the steps of closing forceps to clamp one end of an adhesive tape, adhering weights to the other end of the adhesive tape, fixing the ophthalmic microsurgery forceps by using two 360-degree rotating platforms, adjusting the pitch angle and the roll angle of the forceps through the rotating platforms, realizing angle adjustment on a Z-axis plane and angle adjustment on an XY plane, keeping the weights in a vertical state under the action of gravity, namely keeping acting force on the forceps vertically downwards all the time, projecting vertically downwards gravity to three orthogonal directions at different size components through adjusting the pitch angle and the roll angle, measuring and recording data at certain angle intervals and certain weight intervals, recording grating wavelengths of each group of corresponding FBG sensors through an optical fiber demodulator, finally carrying out data fitting by using a least square method or neural network calculation, and establishing a functional relation between wavelength offset of the FBG sensors and corresponding external force, thereby establishing a measuring model of the force sensing system.

Description

High-sensitivity ophthalmic microsurgery forceps force sensing system and calibration method Technical Field The invention relates to the technical field of sensing, in particular to a high-sensitivity ophthalmic microsurgery forceps force sensing system and a calibration method. Background Retinal microsurgery is a very challenging procedure in the ophthalmic field, whose core steps often involve the treatment of retinal veins and the inner limiting membrane. Since the retinal vein diameters of intraoperative procedures are typically less than 400um, and the thickness of the diseased internal limiting membrane is only about 10um, the physician must perform precise procedures on such extremely delicate tissues within an extremely narrow ocular space. However, current studies indicate that about 75% of the forces in retinal surgery are below 7.5mN, at which level the physician has little to no way to perceive changes in hand, relying on visual observations to infer the interaction state of the instrument with the tissue, which significantly increases the risk of the surgery. If the force applied to the retina is slightly careless, severe complications such as iatrogenic retinal perforation and subretinal hemorrhage are very likely to occur. Therefore, a miniature force sensor instrument capable of accurately detecting and feeding back force information under the scale is developed, and has important clinical significance for improving the safety of operation and reducing the risk of operation. Among the various force sensing techniques, fiber bragg gratings (Fiber Bragg Grating, FBG) are attracting attention due to their characteristics of high compliance with the intraocular surgical scene. Firstly, the sensing unit is directly inscribed on the optical fiber with the diameter of only hundreds of micrometers, the occupied space is small, and the sensing unit can be integrated to key parts such as forceps tips or rod bodies under the condition that the original size and the operation hand feeling of the surgical instrument are hardly changed. Secondly, as a passive sensor based on optical signal modulation, FBGs are not affected by electromagnetic interference at all in surgery and have no electrical safety hazards, which enables them to provide stable and reliable signals in equipment-intensive operating room environments. Meanwhile, the technology is extremely sensitive to strain, can accurately detect milli-bovine-level micro force, and can realize multi-dimensional force/moment decoupling measurement through arrangement of a plurality of gratings. In addition, the optical fiber made of quartz material has good biocompatibility and chemical stability, can bear high temperature and high pressure or chemical sterilization, and completely meets the strict sanitary requirement of repeated use of surgical instruments. Together, these characteristics make FBG one of the most viable technological paths to achieve real-time, accurate force feedback in a narrow, sensitive intraocular environment. The basic configuration of the forceps can be approximately in a slender tubular shape, the basic diameter of the structural dimension required to be penetrated into the eye is not more than 1mm, the dimension of the whole length of the forceps is often in the order of tens of millimeters and is obviously larger than the transverse diameter of the forceps, so that the deformation of the forceps in the axial direction is difficult to detect, in addition, the freedom degrees in the two directions of rotation and feeding are often involved in the process of tearing the membrane of the forceps, in order to realize the compound movement, the nested form of the forceps and the outer sleeve is often adopted, the deformation rigidity is the superposition of the rigidity of the outer sleeve and the forceps when the forceps bear transverse force, and the force sensing effect is also influenced to a certain extent. Secondly, in the current research, most of ophthalmic apparatuses using FBG as a mechanical sensor are fixed on the circumference of a tubular rod, and mechanical calibration is performed by using a weight suspension method or a precision force measuring instrument so as to establish algebraic relation between the wavelength offset of the FBG and the external force. However, in practical application, the ophthalmic microsurgery forceps and the embedded FBG force sensor are of a nested structure, and when external force is transmitted through the forceps jaws, the external force acts on the forceps rod and the FBG force sensor at the same time. The existing calibration method only considers the corresponding relation between the external force and the force sensor, ignores the influence of the self structure of the forceps rod on the transmission and distribution of the external force, causes deviation between the established calibration model and the actual stress state, further influences the accuracy and precision of for