CN100498843C - Computerized cutting and stitching analogy method based on stress analysis and deformation - Google Patents
Computerized cutting and stitching analogy method based on stress analysis and deformation Download PDFInfo
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- CN100498843C CN100498843C CNB2006101476415A CN200610147641A CN100498843C CN 100498843 C CN100498843 C CN 100498843C CN B2006101476415 A CNB2006101476415 A CN B2006101476415A CN 200610147641 A CN200610147641 A CN 200610147641A CN 100498843 C CN100498843 C CN 100498843C
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Abstract
A computer cutting and sewing analog based on force analysis and deformation starts with model build based on material particle spring and central line drawing for soft tissue, rebuilding the object surface, abstracting a central line for the object center. The central line emits a width shaft and connecting with the surface, through center line to drive the surface for integral deformation. A reasonable quick bumping inspection technique is built based on this for cutting and sewing analog. It assimilates the merits of existing method with optimization and integration, realizing accurate and timely analog for computer aided cutting and sewing operation.
Description
Technical field
What the present invention relates to is a kind of analogy method of technical field of image processing, particularly a kind of computing machine cutting and stitching analogy method based on force analysis and deformation.
Background technology
Along with development of science and technology, the operation training can be carried out in the environment the inside of being come out by computer simulation, and the virtual operation object that computer simulation is come out by computer peripheral carries out operating operation.Make the time of operation training shorten dramatically with computing machine sham operated training, reduced the demand of expensive experimental object simultaneously and avoided ethics problem.Because computer simulation operative training system can be the operator training environment that has the sense of reality is provided, can also provide the evaluation of operation exercise.The operation technique object (visual human or organ) that computer simulation is come out undergos surgery, and serious accident can not take place, and can improve doctor's collaboration capabilities, so become a field with extensive prospect by the computer simulation operation.
For the operating method of computer simulation, cutting method in the simulation surgery now, it mostly is topological structure from the grid that changes soft tissue model, come the effect of model cutting, grid on the deletion cutting path that proposes as people such as Saran F in 1999 connects simulates cutting operation and further divides at the triangular plate or the tetrahedron of various surface models and phantom type finally, the method that move on the summit is carried out the effect of topology reconstruction simulation cutting, but all do not add the detailed mechanical analysis of cutting in the simulation that is directed to, be subjected to capillary analysis behind the cutting tool pressure as soft tissue, and the friction force analysis between cutting tool, and the analysis of the deformation of soft tissue in cutting process.
And for the method for sew application in the simulation surgery, A Ladd in 2002 and people such as M.Leduc in 2003 carry out modeling with spring model to suture line in " Toward Modeling of a Suturing Task " (sewing up simulation of task) literary composition on " Graphics Interface proceedings " graphic interface minutes 273-279 page or leaf in 2003, there are some defectives in modeling yet spring model is to suture line, such as the stressed conduction that power could be correct only along the direction of spring the time, and the correct conduction of limitation such as tangible change locality power, simulation between stitching itself and the soft tissue is true to nature inadequately, and sew up and to reflect stressed situation exactly, thereby can not carry out the analysis and the programming of further force feedback well.Joel Brown, S Sorkin, people such as JC Latombe write articles " Algorithmic tools for real-time microsurgery simulation " (algorithmic tool of Minimally Invasive Surgery simulation in real time) at " Medical Image Analysis " (medical image analysis) third phase in September, 2002 the 6th volume 289-300 page or leaf.Wherein the stitching analogy method of Ti Chuing is suture line to be modeled to some rigid bodies in simulation to connect, and has substituted mechanical analysis with the method at reference mark.Though its simulation is true to nature, self collision detect with the knotting operation in realize easily, yet still true to nature inadequately and can not carry out correct analysis in stressed simulation.And J Lenoir, people such as P Meseure carry out modeling with the method for geometric modellings such as spline-fitting etc. to suture line and exist simulation true to nature inadequately or can not carry out defective such as force analysis well in " Medical Simulation " (medical simulation) 2004 3078/2004 volume 105-113 page or leaf " A Suture Model for Surgical Simulation " (for operating suture model) literary composition.
Summary of the invention
The objective of the invention is to overcome deficiency of the prior art, a kind of computing machine cutting and stitching analogy method based on force analysis and deformation is provided.The present invention by simulation in the cutting process at cutting the time soft tissue deformation process, sew up analogy method perfect suture line model track following and force feedback information accurately is provided fast.
The present invention is achieved by the following technical solutions, at first by soft tissue being carried out modeling based on particle spring and center line picture method, the surface of reconstructed object, and take out a center line in object centers, center line is connected to surface ejaculation width of cloth axle and with the surface, drive the surface by center line and produce whole deformation, set up a collision detection technology, cut simulation and sew up simulation.
The method that the computing machine cutting based on force analysis and deformation simulation that the present invention relates to is simulated, concrete steps are as follows:
1. with computing machine cutting tool is carried out the rigid body modeling, cutting tool itself can not operated location cutting tool model by the user, and be carried out collision detection circularly because of stressed generation deformation.
2. carry out collision detection and simulation surface tension, in case detecting cutting tool model and soft tissue model bumps, the surperficial particle of the soft tissue model that contacts with the blade model will follow one on blade model to move, calculate the size of the internal force of spring generation simultaneously, and the stressed size of particle that the critical value that spring breakage relatively takes place and blade model directly contact, in case particle is stressed greater than the maximum surface tension that can bear, just enters for the 3rd step.
3. simulate surface tension dispose procedure and friction force.Comparison surface tension force size and surface fracture critical value, the suffered external force of particle that contacts with the blade model is in case greater than its maximum tension that can bear, spring breakage, at this time the internal force of the spring between the particle has all become restoring force, through the regular hour, particle just self recovery arrives the equilibrium position.Simultaneously, if the blade model continues down motion, will impose a downward friction force f to the mass spring of surrounding tissue.
4. simulate the whole deformation that produces in cutting process, method is as follows:
Because the deformation principle of locality of spring model can't be because of the effect of the whole deformation of stressed generation, so produce the effect of whole deformation here by center line.
Touch soft tissue surfaces from blade and continue the process of down motion to blade, the spring that blade is run into follows blade to move together, detects the stress that soft tissue surfaces produces simultaneously
If
Then with f (∑ F
i) be added on the center line, drive surperficial particle by center line and produce whole deformation.What i represented here is with blade the surperficial particle that contacts, F to be arranged
iBe the size of the suffered external force of i point, K is maximum surface tension, and f is a linear transformation f (x)=kx, according to different operations, can artificially set the k value, and purpose is to make deformation look truer.The k value gets 0.5 in practical operation, when surface tension discharges, discharges the power that is added on the center line simultaneously.
The computing machine based on force analysis and deformation simulation that the present invention relates to is sewed up the method for simulation, and concrete steps are as follows:
1. with computing machine suture line is carried out the rigid body modeling, the rigid body that suture line is modeled as a plurality of points connects, and does not establish the gravity field force, various field forces such as magnetic field force.
2. the suture line to simulation carries out track following.With the reference mark tracing suture line model is carried out track following.The point that is subjected to external force on the reference mark tracing definition suture line is the reference mark, specifically is defined as suture line model starting point and the interactional point that passes the soft tissue model surface by the syringe needle traction here.Displacement situation by the reference mark determines other each non-reference mark displacements.Suture line passes soft tissue and produces a duck eye in the actual sew application, produces friction force by this duck eye.This duck eye is modeled to and fits to a point with passing the reference mark of soft tissue model and nearest surperficial particle here, motion together, be sewn the operation that furthers in the object two ends the most at last in order to simulate suture line, acquiescence suture line model end node can not pass through soft tissue surfaces, promptly the slip behavior can not take place.If last point of suture line model has also become the reference mark, then utilize this special terminal reference mark, thereby will being sewn the object two ends, the pulling force that can slowly strengthen suture line model end furthers.
3. carry out collision detection circularly, in case detecting syringe needle and soft tissue model surface produces when colliding, syringe needle drives the surperficial particle movement that is in contact with it, while gauging surface tension force, the i.e. external force that is subjected to of the surperficial particle that contacts with syringe needle, if it is during greater than the maximum surface tension that can bear, the behavior of piercing through, the external force that the surperficial particle that the release soft tissue model contacts with syringe needle is subjected to, and first node of suture line model is made as the reference mark, surperficial particle and this reference mark that it is nearest fit to a point, together motion.
4. simulate friction force and suture line slide.To each reference mark N
iSurperficial particle in the match of reference mark institute calculates the friction force that it is subjected to
Wherein μ is a friction factor,
Represent that the suffered external force F of this particle is at direction of relative movement
On projection.If f＜K, wherein K is a maximal friction, the surperficial particle m that is connected with this reference mark
iContinuation is along with this reference mark motion.Otherwise, as f〉and during K, the reference mark displacement behavior takes place, the simulation slide is about to reference mark N
iA back point be defined as the reference mark, with mass spring m
iBe connected with new reference mark.
5. use the tension force of computing machine cycle calculations suture line model, the method by the iteration of power between each reference mark is calculated the internal force of suture line model, and concrete grammar is: the scanning that starts anew, N
0N
1... N
kBe each reference mark on the suture line, from suture line starting point N
0Find reference mark N backward
i, guarantee N
0N
1, N
1N
2..., N
I-1N
iAll be stretching line segment, and N
iN
I+1Not stretching,, only need calculation level N because there is not tension force in non-stretching line
0To N
iBetween tension force.An at first controlled N
iThe projection of external force on the suture line direction at place
F wherein
iBe N
iThe external force at place.With f
NiApproximate simulation is N in the suture line
I-1N
iThe tension force of section
Obtain a N in the same manner
I-1The projection of external force on the suture line direction at place
N
I-1In order to reach balance, need to satisfy
In like manner, according to said method iteration draws
Up to the suture line starting point,
Be that suture line initiating terminal (sewing needle) should externally applied forces.
6. whole deformation in the process of simulation stitching, the center line by model is transmitted to integral body with local deformation, the whole deformation that produces in the simulation sewing process, method is as follows:
Because the deformation principle of locality of spring model can't be because of the effect of the whole deformation of stressed generation, so produce the effect of whole deformation here by center line.
Touch soft tissue surfaces from blade and continue the process of down motion to blade, the spring that blade is run into follows blade to move together, detects the stress that soft tissue surfaces produces simultaneously
If
, then with f (∑ F
i) be added on the center line, drive surperficial particle by center line and produce whole deformation.What i represented here is with blade the surperficial particle that contacts, F to be arranged
iBe the size of the suffered external force of i point, K is maximum surface tension, and f is a linear transformation f (x)=kx, according to different operations, can artificially set the k value, and purpose is to make deformation look truer.The k value gets 0.5 in practical operation, when surface tension discharges, discharges the power that is added on the center line simultaneously.
Cutting method of the present invention is at the deformation characteristics of soft tissue, in the local and whole effect that can both simulate the soft tissue cutting fast realistically, rather than simple topology reconstruction, the method that simulation is sewed up has been inherited the reference mark tracing and has been reached and calculate effect fast, and can calculate the tension force of each section of suture line model fast and relatively accurately by iteration tensiometer algorithm, can carry out the force feedback programming further relatively accurately, can be quick, simulation is cut and sew application exactly.
Description of drawings
Fig. 1 is the process flow diagram with the cutting of computer simulation
Fig. 2 is the process flow diagram with the stitching of computer simulation
Embodiment
Below in conjunction with accompanying drawing embodiments of the invention are elaborated: present embodiment has provided detailed embodiment and process being to implement under the prerequisite with the technical solution of the present invention, but protection scope of the present invention is not limited to following embodiment.
After from CT or DICOM data, reading blood vessel data, use the method for computing machine simulated blood vessel cutting by step shown in Figure 1:
(1) by blood vessel being carried out modeling, cutting tool is carried out the rigid body modeling based on the modeling method of particle spring model and center line picture.
(2) by interactive device, mouse or force feedback equipment are controlled empty blade model and are moved.
(3) surface tension in the simulation cutting process, when blade model and vascular pattern collision, the surperficial particle of the vascular wall that bumps is along with cutting tool moves together, the surface spring does not rupture, simultaneously by system-computed surface tension size, when surface tension during greater than maximum surface tension, the process that surface tension discharges is simulated in the spring breakage of simulated blood vessel wall surface then.
(4) simulation friction force.Continuation is moved by peripheral unit control blade model, and the blade model ruptures up to it fully to the friction force of virtual vascular wall in the simulation cutting process, and the operation of whole simulated blood vessel cutting is finished.
Press step shown in Figure 2 method by the computer simulation vascular suture:
(1) the virtual blood vessel that simulates by particle spring model and center line picture in computing machine, and suture instrument carried out the rigid body modeling.
(2) by interactive device, the syringe needle of mouse or force feedback equipment control suture line model moves, and drives the suture line model by syringe needle and moves.
(3) simulate the operation of piercing through.When virtual syringe needle and the collision of virtual vascular wall, the particle that bumps is along with syringe needle moves together, the surface spring does not rupture, simultaneously by COMPUTER CALCULATION surface tension size, when the suffered surface tension of particle during greater than maximum surface tension, the behavior of piercing through, virtual syringe needle penetrates soft tissue model, the process that simulated blood vessel wall surface tension force discharges.
(4) simulation slide and friction force.Continuation is moved by the computer simulation suture instrument, pierces through the virtual vascular wall that the other end is sewn.Calculate suture line track and sutural each section tension force size of utilization iteration tensiometer algorithm computation simulation by system according to the reference mark tracing simultaneously.
(5) continue by peripherals " tension " suture line model, because suture line model last point is as special reference mark, can not pass through the vascular wall model, by iteration tensiometer algorithm, tension force increases gradually, virtual vascular wall two ends are finally moved to together by the suture line model, and fit to a bit, finish the process of whole simulation sew application.
Claims (4)
1, a kind of method of simulating based on the computing machine cutting of force analysis and deformation is characterized in that concrete steps are as follows:
1. with computing machine cutting tool is carried out the rigid body modeling, cutting tool is operated location cutting tool model by the user, and carries out collision detection circularly;
2. collision detection and simulation surface tension are stressed greater than the maximum surface tension that can bear when particle, just enter for the 3. step;
3. simulate surface tension dispose procedure and friction force, comparison surface tension force size and surface fracture critical value, the suffered external force of particle that contacts with the blade model is in case greater than its maximum tension that can bear, spring breakage, at this time the internal force of the spring between the particle has all become restoring force, then, particle just self recovery to the equilibrium position; Simultaneously, when the blade model continues down to move, will impose a downward friction force f to the mass spring of surrounding tissue;
4. simulate the whole deformation that produces in cutting process, the center line by model is transmitted to integral body with local deformation;
Described step is collision detection and simulation surface tension 2., be meant: when detecting cutting tool model and soft tissue model and bump, the surperficial particle of the soft tissue model that contacts with the blade model will follow one on blade model to move, calculate the size of the internal force that spring produces simultaneously, and the stressed size of particle that directly contacts of the critical value that spring breakage relatively takes place and blade model;
Described step 4., its method is as follows:
Touch soft tissue surfaces from blade and continue the process of down motion to blade, the spring that blade is run into follows blade to move together, detects the stress that soft tissue surfaces produces simultaneously
When
The time, then with f (∑ F
i) be added on the center line, drive surperficial particle by center line and produce whole deformation,
What i represented here is with blade the surperficial particle that contacts, F to be arranged
iBe the size of the suffered external force of i point, K is maximum surface tension, and f is a linear transformation f (x)=kx, according to different operations, can artificially set the k value.
2, the method for computer simulation based on force analysis and deformation according to claim 1 is characterized in that, described k value, and the k value gets 0.5 in practical operation, when surface tension discharges, discharges the power that is added on the center line simultaneously.
3, a kind of computing machine based on force analysis and deformation is sewed up the method for simulating, and it is characterized in that concrete steps are as follows:
1. with computing machine suture line is carried out the rigid body modeling, the rigid body that suture line is modeled as a plurality of points connects;
2. the suture line to simulation carries out track following, acquiescence suture line model end node can not pass through soft tissue surfaces, when last point of suture line model has also become the reference mark, then utilize this special terminal reference mark, further thereby the pulling force of increasing suture line model end will be sewn the object two ends;
3. carry out collision detection circularly, moved with surperficial particle in the reference mark;
4. simulate friction force and suture line slide;
5. the method for passing through the iteration of power between each reference mark is calculated the internal force of suture line model, with the tension force of computing machine cycle calculations suture line model;
6. whole deformation in the process of simulation stitching, the center line by model is transmitted to integral body with local deformation;
3. step is meant: when detecting syringe needle and soft tissue model surface and produce collision, syringe needle drives the surperficial particle movement that is in contact with it, gauging surface tension force simultaneously, the i.e. external force that is subjected to of the surperficial particle that contacts with syringe needle;
The whole deformation that produces in the described simulation sewing process, method is as follows:
Touch soft tissue surfaces from blade and continue the process of down motion to blade, the spring that blade is run into follows blade to move together, detects the stress that soft tissue surfaces produces simultaneously
When
The time, then with f (∑ F
i) be added on the center line, drive surperficial particle by center line and produce whole deformation, what i represented here is with blade the surperficial particle that contacts, F to be arranged
iBe the size of the suffered external force of i point, K is maximum surface tension, and f is a linear transformation f (x)=kx, and according to different operations, the k value defined is 0.5 in practical operation, when surface tension discharges, discharges the power that is added on the center line simultaneously.
4, the method for sewing up simulation based on the computing machine of force analysis and deformation according to claim 3, it is characterized in that, step 3. in, when external force during greater than the maximum surface tension that can bear, the behavior of piercing through discharges the external force that surperficial particle that soft tissue model contacts with syringe needle is subjected to, and first node of suture line model is made as the reference mark, surperficial particle and this reference mark that it is nearest fit to a point, together motion.
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Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101295409B (en) * | 2008-06-05 | 2010-04-14 | 上海交通大学 | Shape-changing object real-time simulation system of virtual operation system |
| CN102665836B (en) * | 2009-12-25 | 2015-06-17 | 英特尔公司 | Graphical simulation of objects in a virtual environment |
| CN102855353B (en) * | 2012-08-20 | 2016-11-23 | 上海交通大学 | A kind of real time simulation method of embedded suturing skill |
| CN104679918A (en) * | 2013-11-26 | 2015-06-03 | 中国科学院深圳先进技术研究院 | Method, device and system for simulating haptic interaction between bone drill and bone |
| CN103729555B (en) * | 2013-12-20 | 2019-03-01 | 深圳先进技术研究院 | A kind of method and apparatus of simulation blood flow and vascular wall effect |
| CN105868425B (en) * | 2015-01-19 | 2020-01-10 | 北京大学 | Multi-rigid-body collision simulation method based on precise wave effect |
| CN106777658B (en) * | 2016-12-12 | 2020-02-18 | 南京信息工程大学 | Stitching simulation method based on relaxed LRA constraint algorithm |
| CN109009434A (en) * | 2018-08-15 | 2018-12-18 | 苏州大学张家港工业技术研究院 | Abdominal minimally invasive Robot Virtual operation method |
| CN109616211B (en) * | 2018-12-20 | 2023-05-02 | 南昌大学 | Mixed suture line model based on mass point springs and knotting method thereof |
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