CN109009434A - Abdominal minimally invasive Robot Virtual operation method - Google Patents

Abstract

The invention discloses a virtual operation method of a minimally invasive abdominal surgery robot. Control; b. Establish a physical model of the surgical object, perform force balance calculations, and realize the simulation operation and force-sense interaction of the surgical object's pressing deformation and clamping deformation; c. Establish the mesh model of the surgical object, and simulate the cutting of the surgical object; d. The spring model is used to establish sutures, and the suture knotting simulation; e. By analyzing the friction and tension involved in the interaction between the suture and the soft tissue, the suture simulation process of the surgical object is realized. The robot virtual surgery method for minimally invasive surgery of the abdominal cavity of the present invention can simulate the whole process of surgery, and has high precision and strong real-time performance.

Description

Robotic virtual surgery method for minimally invasive abdominal surgery

technical field

The invention relates to a virtual operation method of a minimally invasive abdominal surgery robot.

Background technique

Virtual reality technology is a computer simulation system that can create and experience virtual worlds. It takes computer technology as the core and combines a variety of related technologies to generate an interactive environment with high myopia in vision, hearing and touch, providing users with an immersive feeling, and can observe the three-dimensional space without limitation. things.

Virtual surgery is a typical application of virtual reality technology in the medical field. As a new research direction, it is a new research field integrating biomechanics, mechanics, medicine, robotics and many other disciplines. Virtual surgery is a surgical system that starts from medical image data, builds a virtual surgical environment in the computer, and then builds a human tissue model, and uses force-tactile interaction equipment to interact with it. Doctors can use the information in the virtual surgical environment for surgical planning, surgical training, surgical rehearsal, and surgical guidance during the actual surgical process.

Minimally invasive surgical robot has become a research hotspot in the field of medical robotics. It combines traditional medical equipment with information technology and robotics, making surgical diagnosis and treatment minimally invasive, miniaturized, intelligent and digital. Compared with traditional surgery, minimally invasive surgical robots have significant advantages: minimally invasive robotic surgery can improve the working mode of doctors, making doctors more dexterous, convenient and precise when performing operations, and even allowing two different fields of surgery The doctor performs two related operations at the same time; in addition, even if the operation is performed for a long time, the minimally invasive surgical robot will not tremble due to fatigue like a human hand, which greatly improves the quality of the operation and prolongs the professional life of the surgeon; minimally invasive surgery The incision of the robot surgery is only about 1 cm, which greatly reduces the blood loss and postoperative pain of the patient, and the patient recovers quickly. The wounds of the large intestine and stomach only need five to seven days to heal, and the skin wounds heal in one or two days. Healing is faster after surgery. The above advantages make the robot the best assistant for doctors.

Nonetheless, current robotic surgical procedures have some significant drawbacks compared to traditional minimally invasive procedures. Doctors cannot directly observe the environment of the operation area, but can only obtain lesion information through the endoscope, and control surgical instruments to operate on the lesion according to the information fed back by the endoscope. Compared with traditional minimally invasive surgery, the active area of surgical instruments is limited, and doctors can only control surgical robots to perform surgical operations in a small area, all of which put forward higher requirements for surgeons. Therefore, if surgeons want to be proficient in this new type of operation, they must go through long-term training. At present, there is no better training object except animals and corpses. However, using animals as surgical training objects, on the one hand, animals and human bodies have different anatomical structures, on the other hand, it will also be condemned by the Animal Protection Association; and human corpses cannot be reused.

The research of the virtual surgery system is dedicated to solving these problems and providing an ideal training tool for special surgical operations. Therefore, the study of virtual surgery simulation is of great significance.

Contents of the invention

In order to solve the above technical problems, the object of the present invention is to propose a virtual surgery method for abdominal minimally invasive surgery robot.

In order to achieve the above object, the present invention provides a technical solution: a virtual surgery method for abdominal minimally invasive surgery robot, which includes the following steps:

a. Building a virtual surgery simulation platform, including designing a robot model with a parallelogram telecentric positioning mechanism, performing kinematic analysis on the robot model, solving the forward kinematics and inverse kinematics of the telecentric positioning mechanism, and controlling the virtual robot through force feedback equipment operational control;

b. Establish a physical model of the surgical object, use the axial bounding box algorithm as the collision detection algorithm between the surgical instrument and the surgical object, perform force balance calculations, and realize the simulation operation and force-sense interaction of the surgical object's pressing deformation and clamping deformation;

c. Establish the mesh model of the surgical object, use the axial bounding box algorithm as the collision detection algorithm between the surgical tool and the surgical object, and use the orderly search method of adjacent triangular patches when performing collision detection, and search through the establishment of triangular patch cutting Search through the tree to realize the cutting simulation of surgical objects;

d. Use the spring model to establish the suture line, carry out the motion simulation of the line model, use the method of simulating the force to realize the collision response, and realize the knotting of the suture line by simulating the stretching force, repulsion force and curvature force in the knotting process knot simulation process;

e. By analyzing the friction and tension involved in the interaction between the suture thread and the soft tissue of the surgical object, the suturing simulation process of the surgical object is realized.

Further, the robot model includes a frame and at least one mechanical arm, each mechanical arm includes a first slider connected to the frame through a first sliding joint to move up and down, and rotates with the first slider through a first rotary joint. The connected first rod, the second rod connected to the first rod through the second rotating joint, the third rod connected to the second rod through the third rotating joint, and the fourth rotating joint A pivoting member pivotally connected to the third rod, a first connecting rod rotatably connected to the pivoting member through the fifth revolving joint, and a second connecting rod rotatably connected to the first connecting rod through the sixth revolving joint , the third connecting rod that is rotationally connected with the second connecting rod through the seventh rotary joint, the second slider that is movably connected with the third connecting rod through the second sliding joint, the second slider is connected with the surgical instrument, and the first connecting rod The rod, the second connecting rod and the third connecting rod constitute a parallelogram mechanism.

Further, building a virtual surgery simulation platform in step a also includes adding at least one camera in the virtual surgery environment, controlling the position and direction of the camera through mouse operation, and realizing the movement and rotation of the virtual surgery environment; adding control buttons on the control panel Realized the switching of viewing angle and resetting the position of visual point.

Further, in step b, according to the particle distribution law, determine the force balance calculation method, first judge whether the particle meets the force condition, and then calculate the distance from the end of the surgical instrument to each particle in the area, then calculate the force of each particle, and then calculate The force feedback in the process of pressing and deforming the surgical object is realized, and the simulation operation and force-sense interaction of the pressing and deforming of the surgical object are realized.

Further, in step b, the physical model of the surgical object is established by using the mass spring method. When the clamping tool is in contact with the surgical object and is in the clamping state, it is judged whether the adhesion point moves together with the clamping tool. If it moves, pass The single-point force balance calculation method is used to calculate and judge whether the adhesion point has reached the force balance state; when the adhesion point reaches the force balance state, the single-point force balance calculation method is used to calculate and judge whether the mass points around the adhesion point have reached the force balance state. Force balance state; when the surrounding mass points are in their respective single-point force balance state, then calculate the resultant force of adjacent points on these points at this time, if these points are within the allowable error range of the overall force balance, Then the system is considered to be in a state of force balance; then the force feedback calculation is performed to collect the position information of the contact point between the apex of the clamping tool and the surface of the soft tissue of the surgical object and the actual position information of the apex of the clamping tool. The clamping tool is clamping the simulation model, the adhesion point moves with the clamping tool, and the surgical object model is deformed. The deformation of the spring is obtained by the vector formed by the position of the mass point before deformation and the position of the mass point after deformation. According to The set spring coefficient calculates the magnitude and direction of the virtual force feedback, and realizes the simulation operation and force-sense interaction of the clamping deformation of the surgical object.

Furthermore, the single-point force balance calculation method includes: b1. Assuming that the mass points around the point are fixed, calculate the resultant force of the adjacent points on the point, and then calculate the displacement of the point under the action of the force, At this time, calculate the resultant force of the adjacent points on the adhesion point again. If the magnitude of the force is within the error range allowed by the single-point force balance, it is considered that the point has reached the force balance state; b2. If it is not within the allowable error range, then It is also required to take the displacement of the point under the resultant force, and then move the point to the corresponding displacement in the direction of the resultant force, and repeat step b1 until the resultant force received by the point is within the allowable error range, then the point reaches the state of force balance .

Further, in step c, the straight line where the two blades of the surgical knife are located is projected onto the plane where the triangular facet is located in the mesh model to obtain the cutting line segment at the current moment, and through the simultaneous spatial straight line equation and each triangular facet The equation of the straight line where the side is located is used to obtain the cutting point of the surgical tool on the surgical object; a threshold d is set on both sides of the cutting line; first, it is judged whether there is a vertex within the threshold, and if so, the vertex is moved to the cutting point position, forming a new vertex; if not, a new cutting intersection point is generated at the intersection of the cutting line and the edge line of the triangular patch; after all intersections are determined, the old patch is removed to form a new triangular patch; and then the tool is calculated The normal of the plane, copy the cutting intersection, divide all the cutting intersections into two groups according to the positive and negative directions of the normal, and then translate the two groups of intersections by a certain distance according to the positive and negative directions of the normal, the intersection point and the same normal direction The vertices of the new triangular surface are formed; finally, the mesh model and the geometric model of the operation object are updated to form an incision.

Further, in step d, the track of the line is tracked by using the method of tracking control points, so as to realize the motion simulation of the line model.

Further, in the virtual suturing operation, when the needle punctures the soft tissue of the surgical object, an external force is applied to the soft tissue, causing the surface tension of the soft tissue. When the surface tension generated by the spring is greater than the maximum surface tension that can be tolerated, the penetration occurs, and The spring particle of the soft tissue is pulled by friction. Since the particle itself is constrained by other particles, when the particle deviates too far from the original position, the force of the particle by other particles will be greater than the frictional force, and sliding will occur.

Due to the adoption of the above technical scheme, the present invention establishes a three-dimensional model of the main abdominal organ tissues, builds a virtual surgical environment, builds a virtual surgery simulation platform, designs an abdominal surgical robot, and performs the abdominal minimally invasive surgical robot virtual surgery method of the present invention. It has carried out kinematic analysis, established a biomechanical model of the internal abdominal tissue for minimally invasive abdominal surgery, and carried out virtual surgery simulation studies such as pressing, clamping, cutting, and suturing, and can simulate the entire operation with high accuracy. , strong real-time performance, doctors can repeat surgical training for surgical patients in the virtual surgical environment, which saves the cost of doctor training, shortens the time of surgical training, and improves the proficiency of surgeons. The establishment of a virtual surgery simulation system can provide doctors with surgical rehearsals, prolong the professional life of doctors, and also realize remote assistance and simulation to determine the surgical plan. This robotic virtual surgery method for minimally invasive abdominal surgery has great theoretical and practical significance for robotic surgery in abdominal surgery.

The above description is only an overview of the technical solutions of the present invention. In order to understand the technical means of the present invention more clearly and implement them according to the contents of the description, the preferred embodiments of the present invention and accompanying drawings are described in detail below.

Description of drawings

Accompanying drawing 1 is the part schematic diagram of virtual environment in the virtual operation method of abdominal minimally invasive surgery robot of the present invention;

Accompanying drawing 2 is the first structural schematic diagram of the robot model in the robot virtual operation method of minimally invasive surgery of the abdominal cavity of the present invention, wherein, only one mechanical arm is drawn for illustration;

Figure 3 is a schematic diagram of the second structure of the robot model in the robot virtual surgery method for minimally invasive abdominal surgery according to the present invention, in which only one mechanical arm is drawn for illustration.

The labels in the figure are:

100. Mechanical arm;

111, the first slider; 112, the first rod; 113, the second rod; 114, the third rod; 115, the pivot member, 116, the first connecting rod; 117, the second connecting rod; 118, The third connecting rod; 119, the second slider;

121. The first sliding joint; 122. The first rotating joint; 123. The second rotating joint; 124. The third rotating joint; 125. The fourth rotating joint; 126. The fifth rotating joint; 127. The sixth rotating joint; 128 , the seventh rotary joint; 129, the second sliding joint;

200. Surgical instruments;

300, frame;

400. Trolley; 500. Display.

Detailed ways

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

With reference to accompanying drawings 1 to 3, the method of virtual surgery for minimally invasive abdominal surgery robot in this embodiment uses 3DMAX to carry out geometric modeling of the involved human abdominal cavity tissue models, virtual surgical robots, surgical instruments, etc., and sets related models Local coordinates and other related parameters; use Deep Exploration to add materials, textures and other related information to these models to increase their authenticity, and finally export and save them as .3ds data format. Combining the software and hardware equipment involved in the virtual surgery of abdominal surgery, a virtual surgery simulation platform is built. Add a camera in the virtual surgery environment, control the position and direction of the camera through mouse operation, and realize the forward, backward, up, down, and rotation of the virtual surgery environment; add control buttons on the control panel to realize the viewing angle in the front, back, left, and right directions Switching and resetting the position of the visual point achieve the effect of roaming in the virtual surgery scene.

Design a robot model with a parallelogram telecentric positioning mechanism, which includes a frame and at least one mechanical arm 100 connected to the frame, and each mechanical arm 100 includes a position adjustment mechanism and a telecentric mechanism that can be controlled by a control device . Each robotic arm 100 has nine joints and nine degrees of freedom. As shown in accompanying drawings 2 and 3, the mechanical arm 100 includes a first sliding block 111 connected to the frame 300 by moving up and down through a first sliding joint, and is rotationally connected with the first sliding block 111 through a first rotating joint. The first rod 112, the second rod 113 that is rotationally connected with the first rod 112 through the second rotary joint, the third rod 114 that is rotationally connected with the second rod 113 through the third rotary joint, and the The pivot member 115 that is pivotally connected to the third rod member 114 through the fourth rotary joint, the first connecting rod 116 that is rotationally connected to the pivot member 115 through the fifth rotary joint, and the first connecting rod through the sixth rotary joint 116, the second connecting rod 117 that is rotatably connected to the second connecting rod 117, the third connecting rod 118 that is rotatably connected to the second connecting rod 117 through the seventh rotary joint, and the second sliding rod 118 that is movably connected to the third connecting rod 118 through the second sliding joint. Block 119, the surgical instrument 200 is connected with the second slider 119, and the first connecting rod 116, the second connecting rod 117, and the third connecting rod 118 form a parallelogram mechanism. Specifically, assuming that the X-axis, Y-axis, and Z-axis constitute a space rectangular coordinate system, the rotation axis of the first connecting rod 116, the rotation axis of the second connecting rod 117, and the rotation axis of the third connecting rod 118 are all along the X-axis. Direction setting, the moving direction of the second slider 119 is along the Z-axis direction, the pivot axis of the pivoting member 115 is set along the Y-axis direction, more specifically, the Y-axis is the axis line of the pivoting member 115 . In this embodiment, the rotation range of the pivoting member 115 is ±70° from the center line along the Z-axis direction, and the rotation range of the first link 116 is -30°～60° from the center line along the Z-axis direction. , the moving distance range of the second slider 119 is 250mm, the moving distance range of the first slider 111 is 900-1550mm, the rotation range of the first rod 112 is -120°～20°, the rotation of the second rod 113 The range is ±120°, the rotation range of the third rod 114 is ±100°, the length of the first rod 112 is 670±20mm, and the length of the second rod 113 is 625±20mm.

The robot in this embodiment has four mechanical arms, three of which are connected with surgical instruments 200, and the fourth mechanical arm generally does not participate in surgical operations and is reserved for use.

The aforementioned surgical instrument 200 includes clamping tools (ie, clamps, used for clamping and deforming the surgical object), surgical sticks (for pressing and deforming the surgical object), and scalpels (for cutting the surgical object).

Carry out kinematics analysis on the abdominal surgery robot, solve the forward kinematics and inverse kinematics of the telecentric positioning mechanism, and control the operation of the virtual robot through the force feedback device. What adopted in this embodiment is the Omega 7.0 force feedback device of Force Dimension Company, and Omega 7.0 can realize the translational movement along 3 directions of x, y, z axis and the rotation around 3 axes of x, y, z, and has a hold degrees of freedom. It can provide feedback force in 3 directions of x, y, z axis and a clamping force. Since the terminal surgical instrument of the designed abdominal surgery robot realizes telecentric movement, the telecentric point is located at the incision on the abdominal cavity body surface, and the position and posture of each joint of the telecentric mechanism can be determined by the terminal position of the surgical instrument, so it is only necessary to obtain The position and posture of each joint can be determined through the inverse solution algorithm. The force feedback device Omega 7.0 has seven degrees of freedom: three degrees of freedom in translation, three degrees of freedom in rotation, and one degree of freedom in clamping. The degrees of freedom in translation, rotation, and clamping are decoupled. They are not related to each other, so the three translation degrees of freedom of Omega 7.0 are used to control the end position of the surgical instrument, and finally the position and attitude of each component of the telecentric mechanism are reversed to realize the operation control of the virtual surgical robot by Omega 7.0.

The improved particle spring method is used to establish the physical model of the surgical object, and the axial bounding box (AABB) algorithm is used as the collision detection algorithm between the surgical instrument 200 and the surgical object. According to the particle distribution law, determine the force balance calculation method, first judge whether the particle meets the force condition, then calculate the distance from the surgical instrument ball to each particle in the area, and then calculate the force of each particle, this method avoids the small influence The calculation of free points and non-free points reduces the amount of calculation and improves the simulation speed. On this basis, the force feedback in the process of pressing and deforming the surgical object is calculated, and the simulation operation and force-sense interaction of the pressing and deforming of the surgical object are realized.

Combined with the physical model of the surgical object, the force balance calculation is performed. The physical model of the surgical object is divided into free points and fixed points. When the clamping tool is in contact with the surgical object model and is in the clamping state, the adhesion point (free point) is judged Whether it moves together with the clamping tool, if it moves, calculate and judge whether the adhesion point reaches the force balance state through the single-point force balance calculation method, the specific method is: b1. Assume that the mass points around the adhesion point are fixed, Calculate the resultant force of the adjacent points on the adhesion point, and then calculate the size of the displacement of the adhesion point under the action of the force. At this time, calculate the resultant force of the adjacent points on the adhesion point again. If the magnitude of the force is in If it is within the allowable error range of single-point force balance, it is considered that the point has reached the force balance state; b2. If it is not within the allowable error range, it is also required to take the displacement of the adhesion point under the resultant force, and then move the point along the resultant force direction Move the corresponding displacement, and repeat b1 again until the resultant force at this point is within the allowable error range, then this point reaches the state of force balance. According to the single-point force balance calculation method, calculate the resultant force and displacement of the mass points around the adhesion point respectively, and judge whether the mass points around the adhesion point have reached the state of force balance; when the mass points around the adhesion point are in their respective After the single-point force balance state, then calculate the resultant force of the adjacent points that these points are subjected to at this time. If these points are within the allowable error range of the overall force balance, it is considered that the system is in a force balance state; then proceed Force feedback calculation, collecting the position information of the contact point between the vertex of the clamping tool and the surface of the soft tissue of the surgical object and the actual position information of the vertex of the clamping tool. The simulation model performs the clamping operation, the adhesion point moves with the clamping tool, and the surgical object model deforms. The deformation of the spring can be obtained through the vector formed by the position of the mass point before deformation and the position of the mass point after deformation. According to the set spring The magnitude and direction of the virtual force feedback can be calculated by the coefficient; finally, the simulation algorithm of clamping deformation of the surgical object is designed to realize the simulation operation and force interaction of the clamping deformation of the surgical object.

Establish the mesh model of the surgical object. In the process of establishing the geometric model of the surgical object in 3DMAX, the number of vertices and the density of the mesh must be strictly controlled, and then exported and saved as .3ds data format; import the .3ds data model into Deep In Exploration, the model is then separated from the mesh. Under the premise of ensuring the model is real, smooth and flat, those unnecessary vertices are deleted and the number of triangle faces is reduced. The Axial Bounding Box (AABB) algorithm is also used as the collision detection algorithm between the surgical instrument and the surgical object. Since there are a large number of triangular patches in the surgical object mesh model, when performing collision detection, if all the triangular patches are traversed, the It will lead to a large number of calculations and affect the real-time performance of virtual simulation. In order to meet the real-time requirements of the simulation, the orderly search method of adjacent triangles is adopted, and the search speed is improved by establishing a triangular cut search tree, thereby improving the efficiency of collision detection. Project the straight line where the two blades of the surgical knife are located onto the plane where the triangular facet is located in the mesh model to obtain the cutting line segment at the current moment. By combining the spatial straight line equation and the equation of the straight line where each edge of the triangular facet is located, we get The cutting point of the surgical tool on the surgical object; in order to avoid generating new small units and affecting the simulation effect, set a threshold d on both sides of the cutting line; first judge whether there is a vertex within the threshold, and if so, move the The position of the vertex to the cutting point forms a new vertex; if not, a new cutting intersection point is generated at the intersection of the cutting line and the edge line of the triangular patch; after all the intersection points are determined, the old patch is removed to form a new triangular surface Then calculate the normal of the tool plane, copy the cutting intersection, divide all the cutting intersections into two groups according to the positive and negative directions of the normal, and then translate the two groups of intersections according to the positive and negative directions of the normal. The translation distance can be According to the definition of the effect, the intersection point and the vertex in the same normal direction form a new triangular surface; finally, the mesh model and the geometric model of the surgical object are updated to form an incision.

The spring model is used to establish the suture line, and the method of following the leader (FTL) is used to track the trajectory of the line, and the motion simulation of the line model is realized; because the suture line itself is a slender flexible body, it is not too big. depth, so the traditional method of collision response and methods similar to the penetration depth are not suitable for the collision detection of the line model, so the present invention adopts the method of simulating the force to realize the collision response; Stretch force, repulsion force and curvature force, realize the knotting simulation process of suture thread.

During surgical suturing, the suture needle pierces the tissues and organs to form a small hole, and at the same time, the suture thread passes through the small hole. Due to the effect of friction, the suture thread slides in the small hole on the one hand, and pulls the nearby soft tissue along with it on the other hand. Move, and finally suture the two separated pieces of soft tissue together by tying a knot. In the virtual suturing operation, when the needle penetrates the soft tissue, an external force is applied to the soft tissue, which causes the surface tension of the soft tissue. Penetration occurs when the surface tension generated by the spring is greater than the maximum surface tension it can withstand, and the spring mass of the soft tissue is pulled frictionally. But the mass point on the soft tissue itself is also constrained by other mass points. When the mass point deviates too far from the original position, the action force on the mass point received by other mass points will be greater than the frictional force, and sliding will occur. By analyzing the friction and tension involved in the suture thread's interaction with soft tissue, the suture simulation process of the surgical object is realized.

According to the above-mentioned virtual surgery method for abdominal minimally invasive surgery robot, this embodiment takes the gallbladder as the surgical object, and provides a specific implementation process of virtual surgery simulation, including the following steps:

1. Motion simulation of abdominal surgery robot

Enter the simulation program, the main window includes two parts: the display window and the control panel. The window display is mainly used to update and display the image of the virtual surgical environment; the control panel is mainly used for user input, to complete the initialization of the system, and to realize the positioning of the apocentric point at the incision on the patient's abdominal cavity. It also provides controls such as adjusting the position of the viewpoint and restoring the initial position of the robotic arm. The program enters the motion simulation thread, first determines the parameters of the non-driven control joints, and realizes the positioning of the telecentric positioning mechanism at the incision on the patient's abdominal cavity; then initializes the force feedback device to obtain the position information of Omega 7.0 in the virtual coordinate system, Establish the corresponding relationship between the force feedback device Omega 7.0 and the telecentric mechanism of the abdominal surgery robot; finally, use Omega 7.0 to control the movement of the driveable joints, so that the telecentric positioning mechanism of the robotic arm can complete the corresponding positioning. At this time, the virtual slave hand in the virtual environment has five degrees of freedom, and the micromachine slides along and moves around the telecentric point of the parallelogram mechanism to realize the telecentric positioning movement of the robot.

2. Press gallbladder deformation simulation

When the program enters the virtual surgery simulation cycle, the physical main hand must first be initialized, the position information of the end of the physical main hand in the fourth joint coordinate system of the virtual surgical robot is obtained, and the corresponding relationship between the physical main hand and the virtual surgical instrument is established to realize the force-sense interaction device Telecentric motion control of surgical instruments. Start the gallbladder compression deformation simulation experiment, establish the bounding box of the gallbladder and its subsidiary pipelines and micro-instruments, and enable collision detection. If the bounding boxes do not intersect, the virtual surgical instrument does not collide with the gallbladder, and continue to control the movement of the main hand; if a collision occurs , the virtual micro-device collides with the gallbladder, and the corresponding particles on the physical model of the gallbladder move under the action of external force, which in turn causes a change in position, resulting in deformation of the gallbladder. At the same time, the program calculates the force feedback of the gallbladder to the virtual device, and outputs it to the Omega 7.0 force-sensing device, allowing the operator to perceive the tactile feedback in the gallbladder compression deformation simulation experiment. When the virtual instrument is separated from the gallbladder, the gallbladder returns to its original shape under the action of the virtual spring, and the deformation of the gallbladder disappears.

3. Clamping gallbladder deformation simulation

Start the gallbladder clamping deformation simulation experiment, establish the bounding box of the gallbladder and its auxiliary pipelines and micro-device, enable collision detection, if the bounding box does not intersect, the clamping tool has not collided with the gallbladder, and continue to control the movement of the main hand; Collision, the two clips at the top of the clamping tool collide with the gallbladder, and judge whether the adhesion point moves with the surgical instrument. If the adhesion point does not move with the clamp tool, the gallbladder is not deformed. The connected virtual springs are elongated or shortened under the action of external force, which drives the surrounding free points to move, and the gallbladder deforms. At the same time, the program calculates the force feedback of the gallbladder to the virtual device, and outputs it to the Omega 7.0 force-sensing device, allowing the operator to perceive the tactile feedback in the simulation experiment of gallbladder pressing and clamping. When the clips of the clamping tool are separated, the clamping tool is separated from the gallbladder, and the gallbladder returns to its original shape under the action of the virtual spring, and the deformation of the gallbladder disappears.

4. Cutting simulation experiment

First start the gallbladder cutting simulation experiment, operate the Omega 7.0 force-sensing device, and control the movement of virtual surgical instruments. When the surgical knife collision model collides with the gallbladder model, obtain the triangular patch that collided with the knife, and calculate the projection of the cutting model on the triangular patch, judge whether the cutting line segment intersects with the three sides of the triangle, and judge whether the intersection point is on the side of the triangle. If the intersection point is on the side of the triangle, set the threshold to determine whether there is a vertex within the threshold range. If there is a vertex, move the vertex to the cutting intersection to form a new intersection; if there is no vertex, generate a new vertex at the cutting intersection. Then perform triangular patch subdivision. Find the normal direction of the tool plane, copy the cutting vertices, and translate the two sets of intersection points according to the positive and negative directions of the normal. The mesh model and geometry model of the surgical object are updated to form the incision.

5. Simulation experiment of suture knotting

Initialize the Omega 7.0 device, obtain its position information in the virtual coordinate system, convert it into the motion control information of the line model, and control the movement of the first node of the line model. At this time, the self-collision detection algorithm will continuously perform self-collision on the line model detection. If a collision between two line segments is detected and the distance between the colliding line segments exceeds the safety distance, a repulsive control condition is imposed at the nodes of the relevant line segments, thereby generating a repulsive force that "blocks" the movement between the line segments, Prevent the occurrence of suture penetration, and finally achieve the knotting effect.

6. Suture simulation

When the needle model pierces the soft tissue (the suture needle is not drawn here, but the first node in the suture model can be used as a needle to control the movement of the line model), detect whether the suture line collides with the surface of the soft tissue model . If there is no collision, the suture continues to move under the control of Omega 7.0 without any deformation of the soft tissue; if a collision is detected, various forces begin to be generated, including the static friction between the soft tissue model and the suture. The spring mass in the soft tissue is stressed, and the displacement changes, resulting in deformation. When this static friction force is greater than the maximum static friction force of the tissue, the tissue will be penetrated. As shown in the figure, the spring mass in the soft tissue biomechanical model slides to the next node of the current suture line node. After multiple penetrations, the spring particles of the soft tissue injury are pulled closer under the action of the thread, thereby simulating the effect of the incision being sutured.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention. It should be pointed out that for those of ordinary skill in the art, some improvements can be made without departing from the technical principle of the present invention. and modifications, these improvements and modifications should also be considered as the protection scope of the present invention.

Claims (9)

1. A virtual surgery method for abdominal cavity minimally invasive surgery robot, which comprises the following steps: a. Building a virtual surgery simulation platform, including designing a robot model with a parallelogram telecentric positioning mechanism, performing kinematic analysis on the robot model, solving the forward kinematics and inverse kinematics of the telecentric positioning mechanism, and controlling the virtual robot through force feedback equipment operational control; b. Establish a physical model of the surgical object, use the axial bounding box algorithm as the collision detection algorithm between the surgical instrument and the surgical object, perform force balance calculations, and realize the simulation operation and force-sense interaction of the surgical object's pressing deformation and clamping deformation; c. Establish the mesh model of the surgical object, use the axial bounding box algorithm as the collision detection algorithm between the surgical tool and the surgical object, and use the orderly search method of adjacent triangular patches when performing collision detection, and search through the establishment of triangular patch cutting Search through the tree to realize the cutting simulation of surgical objects; d. Use the spring model to establish the suture line, carry out the motion simulation of the line model, use the method of simulating the force to realize the collision response, and realize the knotting of the suture line by simulating the stretching force, repulsion force and curvature force in the knotting process knot simulation process; e. By analyzing the friction and tension involved in the interaction between the suture thread and the soft tissue of the surgical object, the suturing simulation process of the surgical object is realized. 2. The robotic virtual surgery method for minimally invasive abdominal surgery according to claim 1, characterized in that: the robot model includes a frame and at least one mechanical arm, each of which includes moving up and down through the first sliding joint. The first slider connected to the frame, the first rod connected to the first slider through the first rotary joint, and the first rod connected to the first rod through the second rotary joint The second rod member, the third rod member pivotally connected with the second rod member through the third rotary joint, the pivot member pivotally connected with the third rod member through the fourth rotary joint, and the pivot member through the fourth rotary joint The first connecting rod that is rotatably connected with the pivot member through the fifth revolving joint, the second connecting rod that is rotatably connected with the first connecting rod through the sixth revolving joint, and the second connecting rod through the seventh revolving joint The third connecting rod that is connected to the rod in rotation, the second slider that is connected to the third connecting rod through the second sliding joint, the second slider is connected to the surgical instrument, the first connecting rod, the second Two connecting rods and the third connecting rod constitute a parallelogram mechanism. 3. The robotic virtual surgery method for minimally invasive abdominal surgery according to claim 1, characterized in that: in the step a, a virtual surgery simulation platform is built, and at least one camera is added in the virtual surgery environment, and the camera is controlled by mouse operation The position and direction of the virtual surgery environment can be moved and rotated; control buttons are added to the control panel to switch the viewing angle and reset the position of the visual point. 4. The robotic virtual surgery method for minimally invasive abdominal surgery according to claim 1, characterized in that: in the step b, according to the particle distribution law, determine the force balance calculation method, first judge whether the particle meets the force condition, and then calculate The distance from the end of the surgical instrument to each mass point in the area, and then calculate the force of each mass point, and then calculate the force feedback during the pressing deformation of the surgical object, so as to realize the simulation operation and force-sense interaction of the pressing deformation of the surgical object. 5. The robotic virtual surgery method for minimally invasive abdominal surgery according to claim 1, characterized in that: in the step b, the physical model of the surgical object is established by using the mass spring method, when the clamping tool contacts the surgical object and is in the grip In the holding state, judge whether the adhesion point moves together with the clamping tool. If it moves, calculate and judge whether the adhesion point has reached the force balance state by the single-point force balance calculation method; when the adhesion point reaches the force balance state , and then use the single-point force balance calculation method to calculate whether the mass points around the adhesion point have reached the state of force balance; when the surrounding mass points are in their respective single-point force balance states, then calculate the values of these points at this time. If these points are within the allowable error range of the overall force balance, the system is considered to be in a force balance state; then the force feedback calculation is performed to collect the position of the contact point between the vertex of the clamping tool and the surface of the soft tissue of the surgical object Information and the actual position information of the vertex of the clamping tool. During the simulation of clamping deformation operation of the surgical object, the clamping tool is clamping the simulation model, the adhesion point moves with the clamping tool, and the surgical object model is deformed. Through the deformation The vector formed by the position of the front mass point and the position of the post-deformation mass point is used to obtain the deformation of the spring, and the size and direction of the virtual force feedback are calculated according to the set spring coefficient, so as to realize the simulation operation and force interaction of the clamping deformation of the surgical object. 6. The robotic virtual surgery method for minimally invasive abdominal surgery according to claim 5, characterized in that: the single-point force balance calculation method comprises: b1. Assuming that the mass points around the point are fixed, calculate the force that the point is subjected to The resultant force of adjacent points, and then calculate the size of the displacement of the point under the action of the force, and then calculate the resultant force of the adjacent points on the adhesion point again, if the magnitude of the force is within the error range allowed by the single-point force balance , it is considered that the point has reached the state of force balance; b2. If it is not within the allowable error range, it is also required to obtain the displacement of the point under the resultant force, and then move the point along the direction of the resultant force to the corresponding displacement, and repeat step b1 until the If the magnitude of the resultant force on a point is within the allowable error range, then the point reaches a state of force balance. 7. The robotic virtual surgery method for minimally invasive abdominal surgery according to claim 1, characterized in that: in the step c, the straight line where the two blades on the surgical knife are projected to the plane where the triangular surface in the mesh model is located above, the cutting line segment at the current moment is obtained, and the cutting point of the surgical tool on the surgical object is obtained by combining the spatial straight line equation and the straight line equation of each side of the triangular surface; a threshold d is set on both sides of the cutting line; First judge whether there is a vertex within the threshold, if so, move the vertex to the position of the cutting point to form a new vertex; if not, generate a new cutting intersection at the intersection of the cutting line and the edge of the triangular patch; determine After all the intersections, remove the old patches to form new triangle patches; then calculate the normal of the tool plane, copy the cutting intersections, divide all the cutting intersections into two groups according to the positive and negative directions of the normals, and then follow The positive and negative directions of the normal line translate the two sets of intersection points for a certain distance, and the intersection point and the vertices in the same normal direction form a new triangular patch; finally, the mesh model and the geometric model of the surgical object are updated to form an incision. 8. The robotic virtual surgery method for minimally invasive abdominal surgery according to claim 1, characterized in that: in the step d, the trajectory of the line is tracked by using the method of tracking control points to realize the motion simulation of the line model. 9. The robotic virtual surgery method for minimally invasive abdominal surgery according to claim 1, characterized in that: during the virtual suturing operation, when the needle punctures the soft tissue of the surgical object, an external force is applied to the soft tissue, causing the surface tension of the soft tissue, and when the spring Penetration occurs when the generated surface tension is greater than the maximum surface tension that can be sustained, and the spring mass of the soft tissue is pulled by friction. Since the mass is itself constrained by other mass, when the mass deviates too far from its original position, the The force acting on the mass point by other mass points will be greater than the frictional force, so sliding occurs.