CN1692871A - Three-D curved line shape testing device and method of flexible endoscope - Google Patents

Abstract

A 3D curve shape detecting equipment of flexible endoscope is composed of flexible detecting rod, optical-fibre raster demodulator and computer. Multiple groups of two optical-fibre rasters are uniformly and axially arranged on said flexible detecting rod to form an optical-fibre raster sensing network. Its detecting method includes such steps as determining the proportional coefficient, obtaining wavelength signal, acquiring curvature information, and drawing curve shape.

Description

Flexible endoscope three-D curved line shape testing device and method

Technical field

The present invention relates to a kind of endoscope-shape detection device and method, relate in particular to a kind of three-D curved line shape testing device and method based on optical fiber grating sensing network.

Background technology

The colonoscope endoscope detecting has become the inspection means of widespread usage, the most accurate localization diagnosis large bowel neoplasm, has important value aspect the diagnosis of neoplastic lesion.Based on present technology, the doctor can not understand the shape of endoscope in human body intestinal canal, can only rely on the personal experience to implement to check operation, the doctor also is difficult to utilize the knot button loop to carry out the auxiliary intervention of scope, also cause simultaneously the unexpected in vivo knot button loop of colonoscope phenomenon to take place easily, even perforation, thereby bring bigger misery and dangerous to patient.At present universal mode is by the X ray guidance method that undergos surgery, but there is bigger injury in this method to medical worker and patient body.By transforming colon endoscope, make it to have the ability of colon endoscope that detect in the intravital form of patient, just can implement to check and treatment provides great convenience for the doctor, can further reduce mirror into and move back the mirror process to the latent lesion of colon, alleviate patient's misery.

Aspect the endoscope-shape cognition technology, prior art only is that OLYMPUS company is based on United States Patent (USP) 6,059,718 etc., adopt the magnetic field positioning principle, the space magnetic field of Electromagnetic Launching equipment emission known structure is installed on measured target, at the magnetic field intensity signal of space point induction acquisition and the space distribution rule in known emission magnetic field, is calculated the space coordinates position of this point and the attitude angle of pick off according to pick off.Utilize several same equipment, once sample every a sampling period, sampled data reflects the variation in continuous magnetic field, calculate the locus of each pick off, fit to successive curve with the computer point that these are discrete then, just can carry out three dimensional display on computers, realize the space orientation and the tracking of flexible body, this technology is subjected to the electromagnetic interference in the operating room easily.

Summary of the invention

Purpose of the present invention is to provide a kind of flexible endoscope three-D curved line shape real-time detection apparatus and method, utilizes optical detection means and the electromagnetic interference of avoiding adopting the magnetic field positioning principle to occur.

The object of the present invention is achieved like this, a kind of flexible endoscope three-D curved line shape testing device, comprise that a flexible test rod (4) is characterized in that: device is linked in sequence with a light source (1), a fiber grating demodulation device (2) and a computer (3) by described flexible test rod (4) and forms, two many groups fiber gratings (5) that become a group are set on described flexible test rod (4) vertically, and every fiber grating (5) is uniform vertically grating test point respectively, thereby constitutes optical fiber grating sensing network.

Above-mentioned many groups fiber grating is two groups of totally four fiber gratings, four fiber gratings (5) are along circumferentially sticking in uniform way on the outer wall of flexible test rod (4), and two groups of fiber gratings are symmetrically distributed on the flexible test rod cross section, and every group two fiber gratings are separated by 90 °.

Be provided with the software that conversion of signals is become curve shape in the above-mentioned computer.

A kind of flexible endoscope three-D curved line shape detection method adopts above-mentioned flexible endoscope three-D curved line shape testing device to detect, and is characterized in that this method may further comprise the steps at least:

1. determine the proportionality coefficient of fiber grating

Before detecting beginning, at first determine respectively to organize on the flexible test rod strain signal of fiber grating and the proportionality coefficient K between curvature of curve with the arc-spline curve scaling method;

2. obtain strain signal

Flexible test rod is placed tested position, and the crooked signal of flexible test rod obtains the strain signal of a plurality of discrete points in flexible test rod surface thus by the fiber grating real-time perception;

3. gather strain signal

The strain signal of a plurality of discrete points converts the digital wavelength signal to through a plurality of fiber Bragg grating (FBG) demodulator devices of correspondence, by computer real-time acquisition;

4. calculate curvature

Computer carries out arc-spline curve according to the signal of gathering in real time and demarcates the corresponding relation that obtains after handling between wavelength signals changing value and the flexible test rod curvature value, and calculates the curvature of a plurality of discrete points on the flexible test rod according to this relation;

5. draw pattern curve

Computer is drawn out the pattern curve of testee with recurrence method according to the curvature of a plurality of discrete points on the flexible test rod.

Above-mentioned three-D curved line shape detection method, wherein, the arc-spline curve scaling method of step described in 1. is: for every group of fiber grating, measure earlier flexible test rod several oneself know the central wavelength lambda of the fiber grating under the radius of curvature ρ, obtain proportionality coefficient under each radius of curvature ρ according to formula K=λ * ρ, get the proportionality coefficient K of its meansigma methods then as each group fiber grating.

Above-mentioned three-D curved line shape detection method, wherein, the recurrence method of step described in 5. be, obtains the coordinate figure of each point on the curve according to following curve fitting equation, fits to successive curve then:

x＝o(i-1)x+(ρi-1-ρ _i)cosθ _i-1+ρicosθ

y＝o _(i-1)y+(ρ _i-1-ρ _i)sinθ _i-1+ρ _isinθ

In the formula, θ _I-1≤ θ≤θ _iθ _i=θ _I-1+ Δ θ=θ _I-1+ s/ ρ ₁

The present invention makes it compared with prior art owing to adopted above technology, has following tangible advantage and characteristics:

1. because whole detection system mainly is made up of optical fiber grating sensing network, demodulation instrument and computer, do not need extra auxiliary detection equipment, so the composition of whole system is simple, no radiation injures human body.

2. because three-D curved line shape detection technique of the present invention is to place a plurality of curvature detection fiber gratings on whole tested curve, multiple-point curvature detection is carried out simultaneously with parallel mode, therefore whole shape detection system can be realized real-time detection, this detection technique can be suitable for the curve detection in the tract, also can be suitable for the detection of any space curve, and can reach very high real-time responsiveness.

3. to have size little for the optical fiber grating sensing mode, and the advantage that measuring range is big can be carried out dynamic big strained measurement under microsize.

Endoscope of the present invention three-D curved line shape testing device is formed simple, and detection method is easy, can realize real-time detection.

Description of drawings

Fig. 1 is the structural representation of three-D curved line shape testing device of the present invention, and picture in picture (a) is apparatus system knot figure figure, and figure (b) arranges the partial enlarged drawing that sketch map and " A " locate for the fiber-optic grating sensor of flexible test rod.

Fig. 2 is an optical fiber grating sensing network topological structure sketch map.

Fig. 3 is that one group of fiber grating detects the curvature under 6 kinds of case of bendings of flexible test rod and the graph of relation of center wavelength variation value in one embodiment of the invention.

Fig. 4 is based on the reconstruction schematic diagram of discrete point curvature information.

Fig. 5 is the true form curve of the flexible test rod of one embodiment of the invention figure that takes pictures.

Fig. 6 schemes the showing again of true form curve of the flexible test rod of one embodiment of the invention.

The specific embodiment

A preferred embodiment of the present invention accompanying drawings is as follows:

See also Fig. 1, this flexible endoscope three-D curved line shape testing device is linked in sequence by optical patchcord, holding wire by flexible test rod (4), Wavelength demodulation device (2) and computer (3) and forms.Two groups of totally four sensing networks that fiber grating is formed evenly are set on flexible test rod (4) vertically.Fiber grating (5) is two for every group, and every group two fiber gratings (5) symmetry sticks on the both sides of flexible test rod (4).In computer (3), be provided with the software that conversion of signals is become curve shape.

The testing process of three-D curved line shape detection method of the present invention as shown in Figure 2.This method is implemented by above-mentioned flexible endoscope three-D curved line shape testing device, and its step is as follows:

Before detecting beginning, at first determine respectively to organize on the flexible test rod (4) the proportionality coefficient K of fiber grating (5) with the arc-spline curve scaling method; The arc-spline curve scaling method is: for every group of fiber grating (5), measure the fiber grating central wavelength lambda of flexible test rod (4) under several known curvature radius ρ earlier, obtain proportionality coefficient under each radius of curvature ρ according to formula K=λ * ρ, get its meansigma methods then and organize the proportionality coefficient K of fiber grating (5) as each.

During detection, flexible test rod (4) is placed tested position, the crooked signal of flexible test rod (4) obtains the strain signal of the surperficial a plurality of discrete points of flexible test rod (4) thus by fiber grating (5) real-time perception;

The strain signal of a plurality of discrete points is gathered by computer (3) in real time through a plurality of fiber grating centre wavelength signals of correspondence;

Computer (3) carries out arc-spline curve according to the signal of gathering in real time and demarcates the corresponding relation that obtains after handling between centre wavelength signal and flexible test rod (4) curvature value, and calculates the curvature that flexible test rod (4) is gone up a plurality of discrete points according to this relation;

At last, computer is drawn out the pattern curve of testee with specific recurrence method according to the curvature of the last a plurality of discrete points of flexible test rod (3).

The detection principle of three-D curved line shape testing device of the present invention is: stick on each fiber grating (5) the output center wavelength λ on the flexible test rod (4) and the radius of curvature ρ of fiber grating loca and be inversely proportional to, n is directly proportional with curvature:

λ＝K/ρ＝K×n

Wherein K is a proportionality coefficient.Proportionality coefficient K tries to achieve with the method that arc-spline curve is demarcated.Concrete scaling method is, for each group fiber grating (5), measure earlier flexible test rod 4 several oneself know fiber grating central wavelength lambda under the radius of curvature ρ, obtain proportionality coefficient under each known curvature radius ρ according to formula λ=K/ ρ=K * n, organize the proportionality coefficient K of fiber grating (5) as each with its meansigma methods.Like this, output center wavelength value λ that just can be by each measured fiber grating of data acquisition card and the COEFFICIENT K of demarcating gained are calculated the curvature of fiber grating (5) loca on the flexible test rod 4.

At { B _iTo carry out vector synthetic to carrying out two component of curvature in the coordinate system, synthetic buckling vector k _i, size is:

$\left|k_i\right|=\sqrt{{{\mathrm{<figure-callout\; id="2"\; label="k\; ai"\; filenames="A20051002585400101.png"\; state="\{\{state\}\}">k</figure-callout>}}_{\mathrm{ai}}}^2+{k_{\mathrm{bi}}}^2}$

k _iWith k _AiAngle α _i

${\mathrm{\&alpha;}}_i=\left\{\begin{array}{c}\mathrm{\&pi;}/2(k_{\mathrm{ai}}=0,k_{\mathrm{bi}}>0)\\ -\mathrm{\&pi;}/2(k_{\mathrm{ai}}=0,k_{\mathrm{bi}}<0)\\ 0(k_{\mathrm{ai}}=0,k_{\mathrm{bi}}=0)\\ {\mathrm{tg}}^{-1}(k_{\mathrm{bi}}/k_{\mathrm{ai}})(k_{\mathrm{ai}}>0)\\ {\mathrm{tg}}^{-1}(k_{\mathrm{bi}}/k_{\mathrm{ai}})+\mathrm{\&pi;}(k_{\mathrm{ai}}<0)\end{array}\right.$

After the curvature that has obtained the last some discrete points of flexible test rod (4), just can be according to the curve fitting equation of the following step acquisition based on recurrence method.

1. two component of curvature is synthetic

2. find the solution the position of i+1 point in world coordinate system

3. new kinetic coordinate system { B _I+1Foundation

4.{B _I+1And the derivation of world coordinate system transformational relation

$\left\{\begin{array}{c}{x}_{i+1}\\ y_{i+1}\\ z_{i+1}\\ 1\end{array}\right\}={\left[T_i\right]}^{-1}\left\{\begin{array}{c}{\mathrm{da}}_i\\ d{b}_{\mathrm{<figure-callout\; id="1"\; label="i\; dc\; i"\; filenames="A20051002585400101.png"\; state="\{\{state\}\}">i</figure-callout>}}& \\ {\mathrm{dc}}_i{}_{}\\ 1\end{array}\right\}$

Obtain the coordinate figure of each point on the curve, fit to successive curve then, realize showing again of tested curve, the pattern curve of flexible test rod (4) is drawn.

Below be further described by the detection principle and the testing process of a specific embodiment three-D curved line shape testing device of the present invention and detection method:

Evenly arranged 10 groups of fiber gratings 5 that model is on long 90 centimetres, 0.75 millimeter of an external diameter, flexible test rod 1, each spacing of organizing between the fiber grating 5 is 10 centimetres, as shown in Figure 3.The output signal of the fiber grating of such 4 passages is by an output center wavelength of gathering each fiber grating of demodulation instrument in real time.Proportionality coefficient K for every group of fiber grating 5, by demarcating the output center wavelength λ of each fiber grating of flexible test rod (4) when ρ=infinity (straight line), 90 centimetres, 70 centimetres, 50 centimetres, 40 centimetres, 30 centimetres, 25 centimetres, 20 centimetres case of bendings, according to formula K=λ ρ, proportionality coefficient when calculating each case of bending, averaging then obtains.Figure 4 shows that wherein a certain group fiber grating (5) detects curved curvature under the state and the graph of relation between the output center wavelength λ got of 8 kinds of flexible test rod 3, thereby obtain proportionality coefficient K by scaling method, straight line wherein is according to λ that asks average K afterwards to draw and the graph of a relation between 1/ ρ (curvature n).

The basic ideas that solve space curve reconstruct are, on space curve, set up the kinetic coordinate system of determining by curve tangent line and component of curvature, in kinetic coordinate system, determine osculating plane, in osculating plane, carry out the bending of curve and calculate, and carry out the motion analysis of kinetic coordinate system by buckling vector.

Then rebuild pattern curve according to the curvature of last 10 points of flexible test rod (4).Because the pattern curve of flexible test rod (4) is successive, therefore under the enough little situation of arc length section s, curve can be regarded as arc section that many sections radiuses do not wait or straightway composition, as shown in Figure 5.Wherein with the tangential direction of starting point as the x axle.In order to know the curvature of enough little s, can adopt linear insertion the between known curvature point (detecting acquisition) by fiber grating (5).In being spaced apart 10 centimetres 2, insert 9 points in this example, formed 10 arc sections, that is:

$\left\{\begin{array}{c}{k}_{\mathrm{ai}}=m_{\mathrm{ai}}*s_i+n_{\mathrm{ai}}\\ k_{\mathrm{ai}+1}=m_{\mathrm{ai}}*s_{i+1}+n_{\mathrm{ai}}\\ k_{\mathrm{bi}}=m_{\mathrm{bi}}*s_i+n_{\mathrm{bi}}\\ k_{\mathrm{bi}}=m_{\mathrm{bi}}*s_{i+1}+n_{\mathrm{bi}}\end{array}\right.$

So just can calculate the curvature of each section circular arc easily.After the radius of curvature of known s and each arc section, just can rebuild recurrence method the central coordinate of circle of arc section is obtained, thereby whole tested curve is showed to come again with the curve based on discrete point curvature shown in Figure 5.The reconstruction figure of the true form curve of the flexible test rod (3) that is present embodiment shown in Figure 6.

Claims (6)

1. flexible endoscope three-D curved line shape testing device, comprise that a flexible test rod (4) is characterized in that: device is linked in sequence with a light source (1), a fiber grating demodulation device (2) and a computer (3) by described flexible test rod (4) and forms, two many groups fiber gratings (5) that become a group are set on described flexible test rod (4) vertically, and every fiber grating (5) is uniform vertically grating test point respectively, thereby constitutes optical fiber grating sensing network.

2. flexible endoscope three-D curved line shape testing device according to claim 1, it is characterized in that: described many group fiber gratings (5) are two groups of totally four fiber gratings, four fiber gratings (5) are along circumferentially sticking in uniform way on the outer wall of flexible test rod (4), and two groups of fiber gratings are symmetrically distributed on the flexible test rod cross section, and every group two fiber gratings are separated by 90 °.

3. flexible endoscope three-D curved line shape testing device according to claim 1 is characterized in that: described computer is provided with the software that conversion of signals is become curve shape in (3).

4. a flexible endoscope three-D curved line shape detection method adopts the described flexible endoscope three-D curved line shape testing device of claim 1 to detect, and it is characterized in that: this method may further comprise the steps at least:

1. determine the proportionality coefficient of the corresponding curvature of fiber grating: before detecting beginning, at first determine respectively to organize on the flexible test rod (4) strain signal of fiber grating (5) and the proportionality coefficient K between curvature of curve with the arc-spline curve scaling method;

2. obtain strain signal: flexible test rod (4) is placed tested position, and the crooked signal of flexible test rod (4) obtains the strain signal of the surperficial a plurality of discrete points of flexible test rod (4) thus by fiber grating (5) real-time perception;

3. gather strain signal: the strain signal of a plurality of discrete points converts digital signal to through the fiber Bragg grating (FBG) demodulator device (2) of correspondence; Gather in real time by computer (3);

4. calculate curvature: computer (3) carries out arc-spline curve according to the signal of gathering in real time and demarcates the corresponding relation that obtains after handling between wavelength change signal and flexible test rod (4) curvature value, and calculates the curvature that flexible test rod (4) is gone up a plurality of discrete points according to this relation;

5. draw pattern curve: computer (3) is drawn out the pattern curve of testee with recurrence method according to the curvature of the last a plurality of discrete points of flexible test rod (4).

5. flexible endoscope three-D curved line shape detection method according to claim 4, it is characterized in that: the arc-spline curve scaling method of step described in 1. is: for every group of fiber grating (5), measure the output wavelength changing value of the demodulation instrument of flexible test rod (4) under several known curvature radius ρ earlier, obtain proportionality coefficient under each radius of curvature ρ according to formula K=u * ρ, get its meansigma methods then and organize the proportionality coefficient K of fiber grating (5) as each.

6. flexible endoscope 3D shape fit equation according to claim 4 is obtained the coordinate figure of each point on the curve, fits to successive curve then:

$x=o_{(i-1)x}+({\mathrm{\&rho;}}_{i-1}+{\mathrm{\&rho;}}_1)\cos {\mathrm{\&theta;}}_{i-1}+{\mathrm{\&rho;}}_i\cos \mathrm{\&theta;}$

$y=o_{(i-1)y}+({\mathrm{\&rho;}}_{i-1}-{\mathrm{\&rho;}}_i){\sin \mathrm{\&theta;}}_{i-1}+{\mathrm{\&rho;}}_i\sin \mathrm{\&theta;}$

In the formula, θ _I-1≤ θ≤θ _iθ _i=θ _I-1+ Δ θ=θ _I-1+ s/ ρ ₁

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