Puncture force feeling simulation method based on force feedback

Abstract

The invention relates to a force feedback force sense simulation method, in particular to a puncture force sense simulation method based on force feedback, which comprises the following steps: S1, configuring a virtual model tissue into a two-layer structure comprising an epidermal layer and a corium layer; s2, determining the distance between an initial reset point and a first-layer needle insertion point, and configuring limiting force in the model tissue; s3, configuring tissue layer puncture parameters, wherein the parameters comprise the thickness of a breakthrough area, the thickness of an effect area, the maximum forward puncture force, the maximum reverse extraction force, a forward damping coefficient, a reverse damping coefficient, an upward rotation angle, a downward rotation angle, a viscous force coefficient and a friction force coefficient; and S4, after the equipment advances from the initial point in any direction, the equipment is in contact with the first-layer puncture point. According to the invention, puncture displacement force sense simulation at any angle can be carried out, the simulation breakthrough area and the effect area are defined and configured, the three-dimensional space is completely utilized, and a dimensionality reduction mapping space is not needed.

Description

Technical Field

[0001] The invention relates to a force feedback force sense simulation method, and in particular to a puncture force sense simulation method based on force feedback. Background Art

[0002] With the development of technology in the medical field, virtual medical simulation provides an innovative way for medical education and training. Traditional medical education usually relies on classroom teaching and actual clinical experience, while virtual medical simulation provides a more realistic, interactive and controllable learning environment for medical students and doctors by simulating real medical scenarios and disease conditions, strengthening the theoretical learning of medical knowledge and the cultivation of practical skills, and improving the professional level and clinical decision-making ability of doctors. Virtual medical simulation can also improve medical safety and reduce medical errors. Through virtual medical simulation, medical staff can conduct a large number of operation practices and team collaboration training in a simulated environment, familiarize themselves with medical processes, operation techniques and emergency handling, reduce surgical risks and improve medical quality; through virtual medical simulation, they can train and improve patient care skills and provide more professional nursing services. In order to meet the simulation needs of puncture scenes in medical clinical surgery or nursing, there is an urgent need for a puncture force simulation method that combines force feedback equipment to give the operator puncture force feedback through a combination of virtual and real feedback. Summary of the invention

[0003] The technical problem to be solved by the present invention is that the existing technical solutions have steps of converting from 3D to 2D space and ray collision detection, the operation position of determining the position relationship between the puncture needle and the tissue is limited and the steps are complicated, and additional mapping is required to describe the tissue to be punctured. A puncture force simulation method is provided for simulating the force feedback of the puncture needle in a medical puncture scene using a force feedback device, which can be applied to the puncture simulation of tissues such as skin, muscle, and joint cavity.

[0004] The technical problem to be solved by the present invention is achieved through the following technical solutions. The present invention discloses a puncture force simulation method based on force feedback, comprising the following steps: step S1, configuring the virtual model tissue as a two-layer structure including an epidermis and a dermis, configuring the device reset point as a fixed point in a three-dimensional space, and initializing the force feedback device to the reset position; step S2, determining the distance between the initial reset point and the first-layer needle insertion point, configuring a limiting force in the model tissue, and the limiting force is decomposed into two orthogonal limiting component forces perpendicular to the insertion direction at the insertion point according to the device's own coordinate system; step S3, configuring tissue layer puncture parameters, the parameters including the thickness of the breakthrough zone and the thickness of the effect zone, the maximum forward insertion force, the maximum reverse withdrawal force, the forward damping coefficient, the reverse damping coefficient, and the reverse direction. Upward rotation angle, downward rotation angle, viscosity coefficient and friction coefficient; step S4, after the device is moved forward from the initial point in any direction, the device contacts the first-layer puncture point, and continues to insert the needle to implement puncture into the tissue. Before reaching the critical point, the device is in the breakthrough area, and the device feedback force is configured as the superposition of the breakthrough feedback force and the limiting force; step S5, after the device moves to the critical point, it continues to puncture into the effect area. At this time, the breakthrough feedback force is reduced to produce a breakthrough feeling. The feedback force of the device entering the effect area is configured as a superposition of multiple forces including limiting force, viscosity and friction; step S6, the device continues to insert the needle to implement puncture into the tissue until it reaches the needle insertion point of the next breakthrough area, and jumps to step S4 according to the parameter configuration of the next layer to continue the operation until the entire simulation operation process is completed.

[0005] The technical problem to be solved by the present invention can also be further achieved by the following technical scheme, wherein step S1 comprises configuring each layer of the two-layer structure of the model into two areas, namely a breakthrough area and an effect area, wherein the breakthrough area is used to simulate the feeling of piercing the epidermis and / or fascia structure; and the effect area is used to simulate the feeling of resistance of the puncture needle moving in the muscle and / or fat tissue.

[0006] The technical problem to be solved by the present invention can also be further achieved by the following technical scheme: the upper and lower parts of the epidermis layer are respectively provided with adjacent breakthrough areas and effect areas, and the upper and lower parts of the dermis layer are respectively provided with adjacent breakthrough areas and effect areas, and the effect area of ​​the lower part of the epidermis layer is adjacent to the breakthrough area of ​​the upper part of the dermis layer.

[0007] The technical problem to be solved by the present invention can be further achieved through the following technical scheme, in which the maximum forward penetration force and / or the maximum reverse withdrawal force in step S3 are configured to produce a breakthrough effect in the breakthrough area, and the device will continue to be hindered from moving by the reverse resistance of the tissue in the initial to critical interval. When the resistance reaches a certain threshold, it will instantly decrease, and the breakthrough force feeling of the tissue being punctured will be simulated by the sudden change of the front and rear resistance.

[0008] The technical problem to be solved by the present invention can also be further achieved through the following technical scheme, wherein the forward damping coefficient and / or the reverse damping coefficient in step S3 is configured so that when the device is in the breakthrough zone, a damping force is superimposed on the breakthrough force, and the damping force is calculated according to the current moving speed of the device, and the direction of the damping force is opposite to the direction of the speed.

[0009] The technical problem to be solved by the present invention can be further achieved through the following technical solution, wherein the upward rotation angle and / or downward rotation angle in step S3 is configured to determine the magnitude of the limiting force of the effect area, and when the device enters the effect area in the positive direction, it is configured according to the upward / downward rotation angle parameters.

[0010] The technical problem to be solved by the present invention can be further achieved by the following technical solution, wherein the critical point in step S4 and step S5 is configured as an effect zone needle entry point, and the effect zone needle entry point is configured to be located at the critical surface between the breakthrough zone and the effect zone.

[0011] Compared with the prior art, the present invention has the following advantages:

[0012] (1) The present invention can simulate the displacement force of puncture at any angle. By defining and configuring the simulated breakthrough area and the effect area, it is fully realized by using three-dimensional space without the need for dimensionality reduction mapping space. It only relies on the layer model to describe the tissue to be punctured without relying on additional mapping.

[0013] (2) The present invention realizes a rich puncture force sense by dividing different puncture stages and configuring the force sense of the multi-layer puncture area of ​​the model, combining the superposition configuration of parameters such as breakthrough force, friction force, viscosity force, and restriction force, and utilizing multiple effects superposition feedback;

[0014] (3) The present invention can be combined with application scenarios to propose a method of rotation after puncturing tissue. The angle can be controlled by parameters to simulate the operation of real intravenous infusion medical care. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the real-time puncture structure of the present invention;

[0016] Figure 2 Schematic diagram of the needle insertion point coordinate system according to an embodiment of the present invention;

[0017] Figure 3 is a schematic diagram of the change of the puncture layer after rotation in an embodiment of the present invention; DETAILED DESCRIPTION

[0018] like Figures 1-3As shown, the puncture force simulation method based on force feedback disclosed in the present invention includes the following steps: step S1, configuring the virtual model tissue as a two-layer structure including an epidermis and a dermis, configuring the device reset point as a fixed point in a three-dimensional space, and initializing the force feedback device to the reset position; step S2, determining the distance between the initial reset point and the first-layer needle insertion point, configuring a limiting force in the model tissue, and the limiting force is decomposed into two orthogonal limiting component forces perpendicular to the insertion direction at the insertion point according to the device's own coordinate system; step S3, configuring tissue layer puncture parameters, the parameters including the thickness of the breakthrough zone and the thickness of the effect zone, the maximum forward insertion force, the maximum reverse withdrawal force, the forward damping coefficient, the reverse damping coefficient, the upward rotation angle, the downward rotation angle, and the reverse rotation angle. Angle, viscosity coefficient and friction coefficient; step S4, after the device is moved forward from the initial point in any direction, the device contacts the first-layer puncture point, and the needle is continued to be inserted to puncture into the tissue. Before reaching the critical point, the device is in the breakthrough zone, and the device feedback force is configured as the superposition of the breakthrough feedback force and the limiting force; step S5, after the device moves to the critical point, it continues to puncture into the effect zone. At this time, the breakthrough feedback force is reduced to produce a breakthrough feeling. The feedback force of the device entering the effect zone is configured as a superposition of multiple forces including limiting force, viscosity and friction; step S6, the device continues to insert the needle to puncture into the tissue until it reaches the needle insertion point of the next breakthrough zone, and jumps to step S4 according to the parameter configuration of the next layer to continue the operation until the entire simulation operation process is completed.

[0019] The step S1 includes configuring each layer of the two-layer structure of the model into two areas, a breakthrough area and an effect area, wherein the breakthrough area is used to simulate the breakthrough feeling of piercing the epidermis and / or fascia structure; and the effect area is used to simulate the resistance feeling of the puncture needle moving in the muscle and / or fat tissue. Specifically, the upper and lower parts of the epidermis are respectively provided with adjacent breakthrough areas and effect areas, and the upper and lower parts of the dermis are respectively provided with adjacent breakthrough areas and effect areas, and the effect area of ​​the lower epidermis is adjacent to the breakthrough area of ​​the upper dermis.

[0020] The forward maximum penetration force and / or the reverse maximum withdrawal force in step S3 are configured to produce a breakthrough effect in the breakthrough zone. The device will continue to be hindered from moving by the reverse resistance of the tissue in the initial to critical interval. When the resistance reaches a certain threshold, it will instantly decrease, and the breakthrough force feeling of the tissue being pierced will be simulated by the sudden change of the front and rear resistance. Wherein, the forward damping coefficient and / or the reverse damping coefficient are configured so that when the device is in the breakthrough zone, a damping force will be superimposed on the basis of the breakthrough force, and the damping force is calculated according to the current moving speed of the device, and the direction of the damping force is opposite to the speed direction. Wherein, the upward rotation angle and / or the downward rotation angle are configured to determine the size of the limiting force in the effect zone. When the device enters the effect zone in the forward direction, it is configured according to the upward / downward rotation angle parameters.

[0021] The critical point in step S4 and step S5 is configured as an injection point in the effect area, and the injection point in the effect area is configured to be located at a critical surface between the breakthrough area and the effect area.

[0022] The simulation method described above will be further described below with a real-time example:

[0023] The process of tissue puncture can be divided into two different force sensations: breakthrough sensation and resistance sensation. Taking abdominal puncture as an example, the breakthrough sensation is manifested in that there will be an obvious puncture sensation when the puncture needle pierces the skin. If the puncture continues and encounters the peritoneum, there should be another puncture sensation. After puncturing into the tissue, the needle tip should encounter resistance from the fat when entering the fat, and resistance from the muscle when entering the muscle. Moving the needle in the tissue fluid will encounter resistance from the tissue fluid. Different resistances correspond to different force sensations. Therefore, the present invention designs a corresponding layer model to quantitatively describe the punctured tissue structure to achieve a rich force sensation effect.

[0024] Figure 1 As an implementation example, assume that the tissue contains two layers: the epidermis and the dermis. The model divides each layer into two areas: the breakthrough area and the effect area. The breakthrough area simulates the breakthrough feeling of piercing the epidermis or fascia and other structures; the effect area simulates the resistance feeling of the puncture needle moving in tissues such as muscle or fat;

[0025] Premise: The virtual puncture needle is the force feedback device (hereinafter referred to as the device), and the device point is the tip of the device, recorded as point The device reset point is a fixed point in three-dimensional space (for different embodiments, the initial position of the reset point in three-dimensional space is the same), denoted as point When resetting, the device point moves to the reset point. Both the world coordinate system and the device's own coordinate system are right-handed coordinate systems. In the world coordinate system, the device's own coordinate system is expressed as like Figure 2 shown.

[0026] Outside the punctured tissue, the device can rotate around the reset point along any axis at any angle; without special scenarios and instructions, the device's direction of travel is only the direction of its own coordinate system. Axis direction, The vector is denoted as The maximum feedback force of the force feedback is MAX_FORCE, and the Z-axis movement range of the force feedback device in its working space is 0 to MAX_Z.

[0027] The operation steps of this embodiment are as follows: initialize the force feedback device to the reset position, determine the initial point The distance between the needle insertion point and the first layer is recorded as the initial distance d (after determining d, The sphere S is determined in three-dimensional space with the sphere center as the radius d. Therefore, any point on the surface of S sphere may become a virtual first-layer needle insertion point in three-dimensional space. When the device actually reaches a point on the surface of S sphere, the point is determined as the virtual first-layer needle insertion point, which is recorded as point At the same time, determine the needle insertion direction as the current Recorded as The current local coordinate system The axis is The current local coordinate system The axis is In the real world, when the puncture needle penetrates the tissue, it will maintain its axial direction without applying external force to the puncture needle. This is because the puncture needle will be squeezed by the surrounding tissue and will not deviate to other directions. For example, if a thin stick is inserted vertically downward into the soil, the thin stick will not fall down after being released. In the present invention, this effect is achieved by limiting the force. After the device penetrates the tissue, the limiting force can be decomposed into the device's own coordinate system along the penetration point according to the force decomposition. Axis force And along Axis The insertion direction is After the device enters the tissue, the force will continue to exist Limit edge Direction deviation Axis; exists in the breakout zone Limit the device in the breakthrough area along Direction deviation axis, in the effect area, Controlled by the UpRotationAngle / UpRotationAngle parameter)

[0028] First, configure the puncture tissue layer structure. The parameter configuration for each layer is as follows:

[0029]

[0030]

[0031] Breakthrough zone thickness hp; when the puncture process determines After that, the needle insertion point of the effect area can be determined by HP and recorded as point

[0032]

[0033] Thickness of effect area he; Needle insertion point of effect area After that, the next breakthrough point can be determined and recorded as point

[0034]

[0035] Forward (penetration) maximum force / reverse (extraction) maximum force; breakthrough zone produces a breakthrough effect, the device to In this interval, the reverse resistance of the tissue will continue to hinder the movement of the device. When the resistance reaches a certain threshold, it will decrease instantly. The sudden change of the front and rear resistances will produce a breakthrough effect, simulating the force of the tissue being punctured. When the device is in the breakthrough zone, it will continue to output feedback force, which is recorded as

[0036] When the device is moving forward, to At this point, the device begins to add positive breakthrough force. point, the positive breakthrough feedback force reaches the maximum value forcePos, when it exceeds When the positive breakthrough feedback force is immediately reduced to 0, the feedback force suddenly decreases, and the difference in resistance before and after forms a sense of breakthrough force.

[0037]

[0038] Reverse (extraction) maximum force; when the device moves in the reverse direction (extraction operation force simulation, that is, from to When the device moves to the point, it also simulates the hindering effect of the tissue structure on the movement of the device. The device begins to add reverse breakthrough force. point, the reverse breakthrough feedback force reaches the maximum value forceNeg, when the reverse exceeds When the reverse breakthrough feedback force is immediately reduced to 0

[0039]

[0040] Forward damping coefficient / reverse damping coefficient; when the device is in the breakthrough zone, the damping force will be superimposed on the breakthrough force. It is calculated based on the current moving speed of the device. The direction of the damping force is opposite to the speed direction. The current speed of the device is recorded as The damping force is

[0041] Forward:

[0042] Reverse:

[0043] Upward rotation angle / downward rotation angle; determines the limiting force of the effect area When the device enters the effect area, according to the configuration of the upward / downward rotation angle parameters, is the rotation origin, around The axis rotates, for example Figure 3 , after the device rotates, the next layers are The center of the circle is deformed into concentric circles to ensure that the hp and he of each layer are the same at all angles; it is mainly used in intravenous injection scenarios to meet the operation process that requires the needle to be inserted into the blood vessel first, then rotated to a horizontal position, and then inserted;

[0044]

[0045] when Time, remember Around The unit vector of the axis rotation upAngle degrees is recorded as

[0046]

[0047] when Time, remember Around The unit vector of the axis rotation downAngle degrees is recorded as

[0048]

[0049] The calculation formula is as follows: So calculate by As reference point

[0050]

[0051] When in the breakout zone, The calculation is as follows:

[0052]

[0053] Maximum viscosity / viscosity coefficient; Viscosity comes from the effect of the liquid in the tissue on the puncture needle, such as blood, joint fluid, etc. The magnitude of the viscosity is related to the type of liquid. For example, a thin rod stirring water and stirring oil are two types of force sensations, which are described by the parameter viscousCoef; The magnitude of the viscosity is also related to the movement speed of the device in the liquid. The greater the movement speed, the greater the resistance should be, and the direction of the viscosity is opposite to the speed direction; The effect area can generate viscosity to simulate the resistance of the liquid in the tissue to the puncture needle. Viscosity Calculated based on the current moving speed of the device

[0054]

[0055] Maximum friction force / friction coefficient; Friction force comes from the effect of the penetrated tissue on the device, which hinders the movement of the device along its insertion direction. For example, if you hold a thin stick tightly with your hand and push and pull it along the axis of the stick, the resistance generated by the palm of your hand on the stick will generate a force on the contact surface that hinders relative motion. The direction of the resultant friction force is opposite to the insertion direction of the device. The magnitude of the friction force is simplified to the product of the friction coefficient and the relative displacement. Friction force According to the calculation of the deviation between the current position of the device and the position of the previous frame, the device position of the previous frame is recorded as The friction force of the current frame is

[0056]

[0057] The device starts from the initial point Along any After moving forward in the direction of d, the device touches the puncture point on the first floor

[0058]

[0059] Continue to insert the needle into the tissue and reach Before the point, the device is in the breakthrough zone, and the feedback force

[0060]

[0061] The equipment moves to After clicking, continue to pierce into the effect area. Reduce the sense of breakthrough and the feedback force of the equipment entering the effect area

[0062]

[0063] Continue to insert the needle into the tissue until the next breakthrough area is reached. Jump to step 5 to continue according to the parameter configuration of the next layer.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A puncture force simulation method based on force feedback, characterized in that: The method comprises the following steps: step S1, configuring the virtual model tissue as a two-layer structure including an epidermis layer and a dermis layer, configuring the device reset point as a fixed point in a three-dimensional space, and initializing the force feedback device to a reset position; Step S2, determining the distance between the initial reset point and the first layer needle insertion point, configuring a limiting force in the model tissue, and the limiting force is decomposed into two orthogonal limiting components perpendicular to the insertion direction at the insertion point according to the device's own coordinate system; Step S3, configuring tissue layer puncture parameters, the parameters include breakthrough zone thickness and effect zone thickness, forward penetration maximum force, reverse withdrawal maximum force, forward damping coefficient, reverse damping coefficient, upward rotation angle, downward rotation angle, viscosity coefficient and friction coefficient; Step S4, after the device is moved forward in any direction from the initial point, the device contacts the first-layer puncture point, and the needle is continued to be inserted into the tissue for puncture. Before reaching the critical point, the device is in the breakthrough zone, and the device feedback force is configured as the superposition of the breakthrough feedback force and the restriction force; Step S5, after the device moves to the critical point, it continues to puncture into the effect area, at which time the breakthrough feedback force is reduced to produce a breakthrough feeling, and the feedback force of the device entering the effect area is configured as a multi-force superposition including a limiting force, a viscous force and a friction force; Step S6, the device continues to insert the needle to puncture into the tissue until the needle insertion point reaches the breakthrough area of ​​the next layer, and jumps to step S4 according to the parameter configuration of the next layer to continue the operation until the entire simulation operation process is completed.

2. The puncture force simulation method based on force feedback according to claim 1, characterized in that: The step S1 includes configuring each layer of the two-layer structure of the model into two areas, a breakthrough area and an effect area. The breakthrough area is used to simulate the feeling of piercing the epidermis and / or fascia structure; the effect area is used to simulate the feeling of resistance of the puncture needle moving in the muscle and / or fat tissue.

3. The puncture force simulation method based on force feedback according to claim 1, characterized in that: The upper and lower parts of the epidermis layer are respectively provided with adjacent breakthrough areas and effect areas, and the upper and lower parts of the dermis layer are respectively provided with adjacent breakthrough areas and effect areas, and the effect area of ​​the lower part of the epidermis layer is adjacent to the breakthrough area of ​​the upper part of the dermis layer.

4. The method for simulating puncture force sensation based on force feedback according to claim 1, characterized in that: The maximum forward penetration force and / or the maximum reverse withdrawal force in step S3 are configured to produce a breakthrough effect in the breakthrough zone. The device will continue to be hindered from moving by the reverse resistance of the tissue in the initial to critical interval. When the resistance reaches a certain threshold, it will decrease instantly, and the breakthrough force feeling of tissue puncture will be simulated through the sudden change of the front and rear resistance.

5. The method for simulating puncture force sensation based on force feedback according to claim 1, characterized in that: The forward damping coefficient and / or reverse damping coefficient in step S3 is configured such that when the device is in the breakthrough zone, a damping force is superimposed on the breakthrough force, and the damping force is calculated according to the current moving speed of the device, and the direction of the damping force is opposite to the direction of the speed.

6. The method for simulating puncture force sensation based on force feedback according to claim 1, characterized in that: The upward rotation angle and / or downward rotation angle in step S3 is configured to determine the magnitude of the limiting force of the effect area. When the device enters the effect area in the forward direction, it is configured according to the upward / downward rotation angle parameters.

7. The method for simulating puncture force sensation based on force feedback according to claim 1, characterized in that: The critical point in step S4 and step S5 is configured as an injection point in the effect area, and the injection point in the effect area is configured to be located at a critical surface between the breakthrough area and the effect area.

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