Method and device for determining robot motion parameters based on puncture needle bending model

Abstract

The present invention provides a method and device for determining robot motion parameters based on a puncture needle bending model, and relates to the technical field of minimally invasive surgical robots. The method comprises: puncturing a soft tissue simulation body with a puncture needle, detecting the medical image of the puncture needle in real time, obtaining the bending feature points of the puncture needle, and establishing a bending model based on the acquired bending feature points; determining the conversion relationship between the robot coordinate system, the image coordinate system, and the bending coordinate system through calibration; solving the robot's forward kinematics model or inverse kinematics model based on the puncture needle bending model, and determining the robot's motion parameters. The present invention can solve the problem of the puncture needle deviating from the predetermined trajectory due to the bending of the puncture needle during the puncture process, and improve the accuracy of puncture.

Description

Technical Field

[0001] The present invention relates to the technical field of minimally invasive surgical robots, and in particular to a method and device for determining robot motion parameters based on a puncture needle bending model. Background Art

[0002] In recent years, with the development of imaging and robotics, imaging-guided puncture robots such as ultrasound (US), magnetic resonance imaging (MRI), and CT have gradually become the main means of interventional treatment for percutaneous and natural cavity puncture, ablation, and biopsy. Under the real-time guidance of imaging equipment, the robot holds the puncture instrument for precise targeted puncture operations, which is minimally invasive, precise, safe and reliable.

[0003] Common image-guided puncture robot systems can scan patients before surgery, accurately determine the location of the lesion, use it as a target, and plan the entry point and puncture path of the puncture instrument before surgery. Finally, the robot combines kinematics to control the puncture instrument to reach the lesion area during surgery to achieve precise targeted puncture. However, during the puncture process, the interaction between the tissue and the needle tip can cause the puncture needle to bend and deform, causing it to deviate from the predetermined trajectory.

[0004] Some existing puncture robots can adjust the puncture angle during the puncture process in combination with mechanical sensors to minimize the bending of the puncture needle, but frequent angle adjustments will cause greater damage to the patient's tissue; in addition, some robots will fit the bending model of the needle according to parameters such as the bevel angle of the puncture needle tip and the elastic modulus of the needle, but the situation during the puncture operation is complicated and the bending is affected by many factors, resulting in poor accuracy of the derived bending curve. Summary of the invention

[0005] In view of the above problems, the purpose of the present invention is to provide a method and device for determining robot motion parameters based on a puncture needle bending model. The method uses a spline curve to fit the curved part of the puncture needle, and uses the fitted curve as the insertion part of the puncture needle. The forward and inverse kinematic models of the robot are derived to determine the motion parameters of the robot, and the puncture path planning is performed based on this. The problem of the puncture needle deviating from the predetermined trajectory due to the bending of the puncture needle during the puncture process can be solved, the puncture accuracy can be improved, and the angle adjustment of the needle during puncture can be minimized to reduce harm to the patient.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] In one aspect, a method for determining robot motion parameters based on a puncture needle bending model is provided, the method comprising the following steps:

[0008] S1. Puncture the soft tissue simulation body with a puncture needle, detect the medical image of the puncture needle in real time, select multiple points in the medical image as bending feature points of the puncture needle, the bending feature points include the needle insertion point, and record each bending feature point in the image coordinate system. pixel The pixel coordinates P pixel ; Establishing a bending model based on the acquired bending feature points of the puncture needle;

[0009] S2. Obtain the puncture target point P target , read its pixel coordinates The coordinates in the robot coordinate system are obtained through imaging calibration relationship. Get the puncture point P entry , and determine the coordinates of the needle entry point in the robot coordinate system Based on the puncture target point P target , the puncture point P entry The bending model determines the robot motion parameters, including the puncture needle angle θ needle and the puncture needle insertion depth Deepth, so that the robot can carry the puncture needle through the needle insertion point P entry Arriving at the puncture target point P target ;or,

[0010] Obtain the degrees of freedom and the elongation of each axis of the robot carrying the puncture needle, and determine the puncture needle angle θ needle , the depth of the needle and the puncture point P entry Based on the bending model, the puncture needle carried by the robot is determined according to the puncture needle angle θ needle , the terminal end point P that can be reached by the needle insertion depth Deepth tip Coordinates in the robot coordinate system And the pixel coordinates in the medical image are obtained through imaging calibration relationship.

[0011] Optionally, the step S1 further comprises the following steps: establishing a bending coordinate system with the needle insertion point as the origin, determining the coordinates P of each bending feature point in the bending coordinate system bend ; A spline curve is fitted to the path of the puncture needle in the curved coordinate system as a curved model.

[0012] Optionally, the spline curve fitting step specifically includes:

[0013] Randomly select k bending feature points from the K bending feature points of the puncture needle, select T groups in total, fit each group of bending feature points with an n-order polynomial spline curve, and add the fitted curve to the candidate set W;

[0014] Each curve in the candidate set W is evaluated, that is, for each curve, the average distance between the other Kk curved feature points in the group and the curve is calculated, and the curve corresponding to the minimum average distance is selected from the candidate set W, which is the best fitting curve C needle .

[0015] Optionally, the best fit curve C needle The choices are as follows:

[0016]

[0017] Among them, d j is the average distance between the jth group of Kk bending feature points and the curve, d m is the minimum average distance, C m is the curve corresponding to the minimum average distance.

[0018] Optionally, in step S1, the puncture needle is used to puncture the soft tissue simulation body horizontally, and a curved coordinate system is established with the puncture point as the origin and the puncture direction as the x-axis. entry .

[0019] Optionally, the puncture needle starts to bend from the insertion point, and the insertion direction is parallel to the x-axis of the bending coordinate system. The curve C is fitted based on the jth group of bending feature points. j The fitting curve is determined and the bending model is established by satisfying the following constraints:

[0020]

[0021] Optionally, the step S2 further includes the following steps: determining the conversion relationship between the robot coordinate system, the image coordinate system and the bending coordinate system through calibration; determining the forward kinematics model or inverse kinematics model of the robot based on the puncture needle bending model, and determining the motion parameters of the robot.

[0022] Optionally, step S2 further includes the following steps:

[0023] Perform imaging calibration on the robot to determine the transformation relationship T from the robot coordinate system to the image coordinate system 1 ; The puncture target point P target Coordinates in the robot coordinate system With its pixel coordinates The relationship is:

[0024]

[0025] Determine the puncture point P on the surface of the soft tissue simulation entry , and the coordinates of the needle entry point in the robot coordinate system Assume the insertion angle of the puncture needle is θ needle , then the curved coordinate system O entry The origin is the needle insertion point P entry , the direction of its x-axis is the direction of needle insertion, and the angle between it and the x-axis of the robot coordinate system is θ needle ;

[0026] Assume that the transformation relationship from the robot coordinate system to the bending coordinate system is T 2 , then:

[0027]

[0028] According to the conversion relationship, the target point P target Coordinates in curved coordinate system It is expressed as:

[0029]

[0030] The target point is located on the curved path of the puncture needle, so its coordinates in the curved coordinate system satisfy the best fitting curve C of the curved model. needle :

[0031]

[0032] Solve to get the puncture angle θ needle , substitute it into T 2 Get the target point P target Coordinates in curved coordinate system

[0033] The length of the curved part of the puncture needle is the puncture depth Deepth, which is calculated by the scalar line integral of the best fitting curve of the bending model:

[0034]

[0035] According to the geometric relationship of the puncture mechanism model, the relationship between the puncture needle posture and the motor shaft state is determined, and the needle insertion angle θ needle , Needle insertion depth Deepth and needle insertion point position P entry Substituting into equation F, determine the elongation of each axis of the robot carrying the puncture needle.

[0036] Optionally, step S2 further includes the following steps:

[0037] Determine the degrees of freedom and the elongation of each axis of the robot carrying the puncture needle, and substitute them into the relationship F between the puncture needle posture and the motor shaft state determined by the geometric relationship of the puncture mechanism model to determine the puncture needle angle θ needle , Needle insertion depth Deepth and needle insertion point P entry ;

[0038] The needle insertion point P entry The curved coordinate system O is established with the puncture needle direction as the x-axis. entry , then from the robot coordinate system O robot To the curved coordinate system O entry The conversion relationship T 2 for:

[0039]

[0040] The puncture needle enters the soft tissue simulation body from the origin and follows the best fitting curve C of the curved model. needle Bend, reach the end point P after reaching the needle insertion depth Deepth tip , let its coordinates in the curved coordinate system be Then the scalar line integral from the origin to the end point satisfies:

[0041]

[0042] Solving the above integral equation, we get Substitute it into the following formula to obtain

[0043]

[0044] Finally, through the coordinate system transformation relationship T 2 Solve to get the end point P of the puncture needle tip In the robot coordinate system O robot The coordinates below

[0045]

[0046] On the other hand, a robot motion parameter determination device based on a puncture needle bending model is provided, which is used to implement any of the above methods, and the device comprises:

[0047] The puncture needle bending model determination module is used to puncture the soft tissue simulation body with the puncture needle, detect the medical image of the puncture needle in real time, select multiple points in the medical image as the bending feature points of the puncture needle, and the bending feature points include the needle insertion point, and record each bending feature point in the image coordinate system O pixel The pixel coordinates P pixel ; Establishing a bending model based on the acquired bending feature points of the puncture needle;

[0048] Robot motion parameter determination module, used to obtain the puncture target point P target , read its pixel coordinates The coordinates in the robot coordinate system are obtained through imaging calibration relationship. Get the puncture point P entry , and determine the coordinates of the needle entry point in the robot coordinate system Based on the puncture target point P target , the puncture point P entry The bending model determines the robot motion parameters, including the puncture needle angle θ needle and the puncture needle insertion depth Deepth, so that the robot can carry the puncture needle through the needle insertion point P entry Arriving at the puncture target point P target ;

[0049] Alternatively, the degrees of freedom and the elongation of each axis of the robot carrying the puncture needle are obtained to determine the puncture needle angle θ. needle , the depth of the needle and the puncture point P entry Based on the bending model, the puncture needle carried by the robot is determined according to the puncture needle angle θ needle , the terminal end point P that can be reached by the needle insertion depth Deepth tip Coordinates in the robot coordinate system And the pixel coordinates in the medical image are obtained through imaging calibration relationship.

[0050] Optionally, the puncture needle bending model determination module is further used to: establish a bending coordinate system with the needle insertion point as the origin, and determine the coordinates P of each bending feature point in the bending coordinate system. bend ; A spline curve is fitted to the path of the puncture needle in the curved coordinate system as a curved model.

[0051] Optionally, the spline curve fitting specifically includes:

[0052] Randomly select k bending feature points from the K bending feature points of the puncture needle, select T groups in total, fit each group of bending feature points with an n-order polynomial spline curve, and add the fitted curve to the candidate set W;

[0053] Each curve in the candidate set W is evaluated, that is, for each curve, the average distance between the other Kk curved feature points in the group and the curve is calculated, and the curve corresponding to the minimum average distance is selected from the candidate set W, which is the best fitting curve C needle .

[0054] Optionally, the best fit curve C needle The choices are as follows:

[0055]

[0056] Among them, d jis the average distance between the jth group of Kk bending feature points and the curve, d m is the minimum average distance, C m is the curve corresponding to the minimum average distance.

[0057] Optionally, in the puncture needle bending model determination module, the puncture needle is used to perform horizontal puncture on the soft tissue simulation body, and a bending coordinate system is established with the puncture point as the origin and the puncture direction as the x-axis. entry .

[0058] Optionally, in the puncture needle bending model determination module, the puncture needle starts to bend from the insertion point, and the insertion direction is parallel to the x-axis of the bending coordinate system. The curve C is fitted based on the jth group of bending feature points. j The fitting curve is determined and the bending model is established by satisfying the following constraints:

[0059]

[0060] Optionally, the robot motion parameter determination module is also used to: determine the conversion relationship between the robot coordinate system, the image coordinate system and the bending coordinate system through calibration; based on the puncture needle bending model, solve the robot's forward kinematics model or inverse kinematics model to determine the robot's motion parameters.

[0061] Optionally, the robot motion parameter determination module is further used for:

[0062] Perform imaging calibration on the robot to determine the transformation relationship T from the robot coordinate system to the image coordinate system 1 ; The puncture target point P target Coordinates in the robot coordinate system With its pixel coordinates The relationship is:

[0063]

[0064] Determine the puncture point P on the surface of the soft tissue simulation entry , and the coordinates of the needle entry point in the robot coordinate system Assume the insertion angle of the puncture needle is θ needle , then the curved coordinate system O entry The origin is the needle insertion point P entry , the direction of its x-axis is the direction of needle insertion, and the angle between it and the x-axis of the robot coordinate system is θ needle ;

[0065] Assume that the transformation relationship from the robot coordinate system to the bending coordinate system is T 2 , then:

[0066]

[0067] According to the conversion relationship, the target point P target Coordinates in curved coordinate system It is expressed as:

[0068]

[0069] The target point is located on the curved path of the puncture needle, so its coordinates in the curved coordinate system satisfy the best fitting curve C of the curved model. needle :

[0070]

[0071] Solve to get the puncture angle θ needle , substitute it into T 2 Get the target point P target Coordinates in curved coordinate system

[0072] The length of the curved part of the puncture needle is the puncture depth Deepth, which is calculated by the scalar line integral of the best fitting curve of the bending model:

[0073]

[0074] According to the geometric relationship of the puncture mechanism model, the relationship between the puncture needle posture and the motor shaft state is determined, and the needle insertion angle θ needle , Needle insertion depth Deepth and needle insertion point position P entry Substituting into equation F, determine the elongation of each axis of the robot carrying the puncture needle.

[0075] Optionally, the robot motion parameter determination module is further used to: determine the degrees of freedom of the robot carrying the puncture needle and the elongation of each axis, and bring them into the relationship F between the puncture needle posture and the motor shaft state determined according to the geometric relationship of the puncture mechanism model to determine the puncture needle angle θ needle , Needle insertion depth Deepth and needle insertion point P entry ;

[0076] The needle insertion point P entry The curved coordinate system O is established with the puncture needle direction as the x-axis. entry , then from the robot coordinate system O robot To the curved coordinate system O entry The conversion relationship T 2 for:

[0077]

[0078] The puncture needle enters the soft tissue simulation body from the origin and follows the best fitting curve C of the curved model. needleBend, reach the end point P after reaching the needle insertion depth Deepth tip , let its coordinates in the curved coordinate system be Then the scalar line integral from the origin to the end point satisfies:

[0079]

[0080] Solving the above integral equation, we get Substitute it into the following formula to obtain

[0081]

[0082] Finally, through the coordinate system transformation relationship T 2 Solve to get the end point P of the puncture needle tip In the robot coordinate system O robot The coordinates below

[0083]

[0084] In another aspect, an electronic device is provided, the electronic device comprising:

[0085] processor;

[0086] A memory having computer-readable instructions stored thereon, wherein when the computer-readable instructions are loaded and executed by the processor, the steps of the above-mentioned method for determining the motion parameters of the robot are implemented.

[0087] On the other hand, a computer-readable storage medium is provided, in which a program code is stored. The program code can be called by a processor to execute the steps of the robot motion parameter determination method as described above.

[0088] The beneficial effects brought about by the technical solution provided by the present invention include at least:

[0089] 1. Compared with the traditional puncture robot kinematic model, the robot motion parameter determination method based on the puncture needle bending model of the present invention combines the puncture needle bending model into the original kinematic model, greatly improving the accuracy and rigor of the kinematic model, solving the problem of drastically adjusting the puncture angle due to bending deviation after the puncture needle enters the body surface, and reducing the harm to the patient.

[0090] 2. Compared with the traditional method of calculating the bending model of the puncture needle through a mechanical model, the method of the present invention uses an n-order polynomial curve to fit the bending model of the puncture needle, and determines the polynomial coefficients through a soft tissue simulation puncture experiment, which greatly simplifies the calculation amount of the bending model and ensures the accuracy and applicability of the model. BRIEF DESCRIPTION OF THE DRAWINGS

[0091] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0092] Figure 1 is a flow chart of a method for determining robot motion parameters based on a puncture needle bending model provided by an embodiment of the present invention;

[0093] Figure 2 is a schematic diagram of pre-puncture provided by an embodiment of the present invention;

[0094] Figure 3 is a schematic diagram of selecting bending feature points of a puncture needle provided in an embodiment of the present invention;

[0095] Figure 4 is a schematic diagram of assembling a puncture robot provided by an embodiment of the present invention;

[0096] Figure 5 It is a schematic diagram of the solution process of the forward and inverse kinematics model provided by an embodiment of the present invention;

[0097] Figure 6 is a schematic diagram of the image coordinate system conversion relationship provided by an embodiment of the present invention;

[0098] Figure 7 is a schematic diagram of the conversion relationship of the curved coordinate system provided by an embodiment of the present invention;

[0099] Figure 8 is a schematic diagram of a planar puncture mechanism provided by an embodiment of the present invention;

[0100] Fig. 9 It is a schematic diagram of the kinematic model of the planar puncture robot provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0101] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0102] In the embodiments of the present invention, words such as "exemplarily" and "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "exemplary" in the present invention should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Rather, the word "exemplary" is used to present the concept in a specific way.

[0103] The embodiment of the present invention provides a method for determining robot motion parameters based on a puncture needle bending model, which can be implemented by an electronic device, which can be a terminal or a server. Figure 1 As shown, the processing flow of the method may include the following steps:

[0104] S1. Determine the bending model of the puncture needle (or bending geometry model, bending shape model).

[0105] In this step, the puncture needle is used to puncture the soft tissue simulation body, and the medical image of the puncture needle is detected in real time. A plurality of points are selected in the medical image as the bending feature points of the puncture needle, and the bending feature points include the needle insertion point. Each bending feature point is recorded in the image coordinate system O pixel The pixel coordinates P pixel ; Establish a bending model based on the acquired bending feature points of the puncture needle.

[0106] Furthermore, the step S1 specifically includes:

[0107] S11. Collecting bending feature points of the puncture needle.

[0108] like Figure 2 As shown, in the pre-puncture, the puncture needle is used to perform horizontal puncture on the soft tissue simulation body, and the medical image of the puncture needle is detected in real time. K points are selected in the medical image as the bending feature points of the puncture needle, and the K bending feature points are recorded in the image coordinate system O pixel The pixel coordinates P pixel :

[0109]

[0110] in, Represents the pixel coordinates of the i-th curved feature point.

[0111] In the embodiment of the present invention, the soft tissue simulation body is a phantom prepared by imitating patient tissue.

[0112] S12. Establish a curved coordinate system.

[0113] The curved coordinate system is a coordinate system established with the puncture point as the origin and the puncture direction as the x-axis. entry .like Figure 3As shown, since S11 is a horizontal puncture, the rotation angle between the current bending coordinate system and the image coordinate system is 0°. According to the resolution S of the imaging device, x , S y and the pixel coordinates P of the needle entry point 0 (x 0 ,y 0 ), determine the coordinates P of the K bending feature points in the bending coordinate system bend :

[0114]

[0115] in,

[0116] Represents the coordinates of the i-th curved feature point in the curved coordinate system.

[0117] In the curved coordinate system, the path of the puncture needle is fitted using a spline curve as a curved model.

[0118] A better spline curve is an n-degree polynomial spline:

[0119] y=a n x n +a n-1 x n-1 +…+a 2 x 2 +a 1 x+a 0 .

[0120] S13, fitting candidate curve;

[0121] K bending feature points are randomly selected from the K bending feature points of the puncture needle, and a total of T groups are selected. Each group of bending feature points is fitted with an n-order polynomial spline curve, and the fitted curve is added to the candidate set W.

[0122] Since the puncture needle starts to bend from the insertion point, and the insertion direction is parallel to the x-axis of the bending coordinate system, the curve C after fitting the j-th group of bending feature points is j The following constraints are met:

[0123]

[0124] It can be written as:

[0125]

[0126] After derivation, we can get curve C j The expression is:

[0127] C j :y=an x n +a n-1 x n-1 +…+a 2 x 2

[0128] Add the fitted curve to the candidate set W:

[0129]

[0130] Among them, w j represents the j-th curve in the candidate set W.

[0131] S14, determining the best fitting curve;

[0132] Each curve in the candidate set W is evaluated, that is, for each curve, the average distance between the other Kk curved feature points in the group and the curve is calculated, and the curve corresponding to the minimum average distance is selected from the candidate set W, which is the best fitting curve C needle .

[0133] Best fit curve C needle The choices are as follows:

[0134]

[0135] Among them, d j is the average distance between the jth group of Kk bending feature points and the curve, d m is the minimum average distance, C m is the curve corresponding to the minimum average distance.

[0136] S2. Determine the motion parameters of the robot carrying the puncture needle.

[0137] In this step, the conversion relationship among the robot coordinate system, the image coordinate system and the bending coordinate system is first determined by calibration; then, based on the bending model of the puncture needle, the forward kinematics model or the inverse kinematics model of the robot is solved to determine the motion parameters of the robot.

[0138] Specifically, the puncture target point P is obtained. target , read its pixel coordinates The coordinates in the robot coordinate system are obtained through imaging calibration relationship. Get the puncture point P entry , and determine the coordinates of the needle entry point in the robot coordinate system Based on the puncture target point P target , the puncture point P entry The bending model determines the robot motion parameters, including the puncture needle angle θ needleand the puncture needle insertion depth Deepth, so that the robot can carry the puncture needle through the needle insertion point P entry Arriving at the puncture target point P target ; The above is the inverse kinematics model of the robot.

[0139] Alternatively, the degrees of freedom and the elongation of each axis of the robot carrying the puncture needle are obtained to determine the puncture needle angle θ. needle , the depth of the needle and the puncture point P entry Based on the bending model, the puncture needle carried by the robot is determined according to the puncture needle angle θ needle , the terminal end point P that can be reached by the needle insertion depth Deepth tip Coordinates in the robot coordinate system And through the imaging calibration relationship, its pixel coordinates in the medical image are obtained; the above is the forward kinematic model of the robot.

[0140] like Figure 4 As shown, in an embodiment of the present invention, a transrectal ultrasound-guided prostate puncture robot is mainly composed of an ultrasonic drive platform 1, an ultrasonic probe 2, a puncture needle pitch mechanism 3, a puncture needle insertion mechanism 4 and a puncture needle 5, wherein the ultrasonic drive platform 1 and the ultrasonic probe 2 can control the stepping and axial rotation of the ultrasonic probe, and the puncture needle pitch mechanism 3, the puncture needle insertion mechanism 4 and the puncture needle 5 form a planar puncture mechanism with three degrees of freedom, which can control the lifting, pitching and insertion of the puncture needle in the plane of the working space.

[0141] In step S2, the solution process of the inverse kinematics model is as follows: Figure 5 As shown in (a), including:

[0142] First, the robot is calibrated by imaging to determine the transformation relationship T from the robot coordinate system to the image coordinate system. 1 .

[0143] like Figure 6 As shown, in the embodiment of the present invention, the conversion relationship is:

[0144]

[0145] Where S x and S y is the ultrasound resolution, Δx and Δy are the coordinates of the origin of the image coordinate system in the robot coordinate system.

[0146] Select the puncture target point P on the medical image target , read its pixel coordinates The coordinates in the robot coordinate system are obtained through imaging calibration relationship (ultrasonic calibration relationship).

[0147]

[0148] Secondly, determine the puncture point P on the surface of the soft tissue simulation body. entry , and the coordinates of the needle entry point in the robot coordinate system The robot needs to control the puncture needle from point P entry Enter the patient's body and finally reach the target point P target Assume that the insertion angle of the puncture needle is θ needle , then the curved coordinate system O entry The origin is the needle insertion point P entry , the direction of its x-axis is the direction of needle insertion, and the angle between it and the x-axis of the robot coordinate system is θ needle .

[0149] like Figure 7 As shown, let the transformation relationship from the robot coordinate system to the bending coordinate system be T 2 , then:

[0150]

[0151] According to the conversion relationship, the target point P target Coordinates in curved coordinate system It is expressed as:

[0152]

[0153] The target point is located on the curved path of the puncture needle, so its coordinates in the curved coordinate system satisfy the best fitting curve C of the curved model. needle :

[0154]

[0155] Right now:

[0156] Substituting this relationship into the above equation, the puncture angle θ is obtained needle , substitute it into T 2 Get the target point P target Coordinates in curved coordinate system

[0157] The length of the curved part of the puncture needle is the puncture depth Deepth, which is calculated by the scalar line integral of the best fitting curve of the bending model:

[0158]

[0159] Then, the relationship F between the puncture needle posture and the motor shaft state is determined based on the geometric relationship of the puncture mechanism model. Finally, the needle insertion angle, needle insertion depth and needle insertion point position are substituted into the relationship F to determine the elongation of each axis of the robot carrying the puncture needle, that is, the solution of the robot inverse kinematics model:

[0160]

[0161] Where DoF is the number of degrees of freedom of the puncture robot, l i is the elongation of each axis.

[0162] As an optional embodiment of the present invention, a schematic diagram of the planar puncture mechanism is as follows Figure 8 As shown, it includes a first axis 101, a second axis 102, a first rod 103, a second rod 104, a third rod 105 and a puncture needle 106. The first axis 101 forms a moving pair with the first rod 103 through a slider, and forms a rotation pair with the third rod 105. The second axis 102 forms a moving pair with the second rod 104 and the third rod 105 through a slider, and the third rod 103 forms a moving pair with the puncture needle 106 through a slider. When the first axis 101 and the second axis 102 move at the same speed, the third rod 105 will be driven to achieve lifting movement; when the first axis 101 and the second axis 102 move at a differential speed, the third rod 105 will be driven to achieve pitching movement; the third rod 105 can drive the puncture needle to extend and retract; the three-axis linkage can control the end of the puncture needle to reach any position in its working space.

[0163] In the embodiment of the present invention, the kinematic model diagram of the planar puncture robot is as follows: Fig. 9 As shown in (a) and (b). Assume:

[0164] l 1 : The elongation of the motor shaft where the first axis 101 is located;

[0165] l 2 : The extension of the motor shaft where the second shaft 102 is located;

[0166] l 3 : The extension of the motor shaft where the puncture needle is located;

[0167] d: initial distance between the first axis 101 and the second axis 102;

[0168] h: vertical distance between the first axis 101 and the puncture needle;

[0169] L 0 : The initial horizontal distance between the first axis 101 and the end of the puncture needle;

[0170] Deepth: needle insertion depth;

[0171] θ needle : The insertion angle of the puncture needle;

[0172] P entry (x entry ,y entry ): Coordinates of the needle entry point in the plane puncture robot coordinate system.

[0173] According to the geometric relationship, the relationship between the puncture needle posture and the motor shaft state is:

[0174]

[0175] By substituting the needle insertion angle, needle insertion depth and needle insertion point position into the relationship, the elongation of each axis of the puncture robot can be determined, that is, the solution of the inverse kinematics model of the puncture robot.

[0176] like Figure 5 As shown in (b), the solution process of the forward kinematics model is as follows:

[0177] First, determine the degree of freedom DoF and the elongation of each axis of the puncture robot. i , put it into the relationship F, and you can determine the puncture angle θ needle , the depth of the needle and the point of entry P entry Location:

[0178]

[0179] Specifically,

[0180]

[0181] The needle insertion point P entry As the origin, the puncture needle direction is the x-axis to establish a curved coordinate system O entry , then from the robot coordinate system O robot To the curved coordinate system O entry The conversion relationship T 2 for:

[0182]

[0183] The puncture needle enters the soft tissue simulation body from the origin and follows the best fitting curve C of the curved model. needle Bend, reach the end point P after reaching the needle insertion depth Deepth tip , let its coordinates in the curved coordinate system be Then the scalar line integral from the origin to the end point satisfies:

[0184]

[0185] Right now:

[0186]

[0187] Solving the above integral equation, we get Substitute it into the following formula to obtain

[0188]

[0189] Right now:

[0190]

[0191] Finally, through the coordinate system transformation relationship T 2 Solve to get the end point P of the puncture needle tip In the robot coordinate system O robot The coordinates below That is, the solution of the robot's forward kinematics model:

[0192]

[0193] Compared with the prior art, the robot motion parameter determination method based on the puncture needle bending model described in the present invention combines the puncture needle bending model into the original kinematic model, greatly improving the accuracy and rigor of the kinematic model, solving the problem of drastically adjusting the puncture angle due to bending deviation after the puncture needle enters the body surface, and reducing the harm to the patient. In addition, the method of the present invention uses an n-order polynomial curve to fit the puncture needle bending model, and determines the polynomial coefficients through soft tissue simulation body puncture experiments, which greatly simplifies the calculation amount of the bending model, takes the preoperative puncture results as a priori, and ensures the accuracy and applicability of the model.

[0194] Accordingly, an embodiment of the present invention further provides a robot motion parameter determination device based on a puncture needle bending model, the device comprising:

[0195] The puncture needle bending model determination module is used to puncture the soft tissue simulation body with the puncture needle, detect the medical image of the puncture needle in real time, select multiple points in the medical image as the bending feature points of the puncture needle, and the bending feature points include the needle insertion point, and record each bending feature point in the image coordinate system O pixel The pixel coordinates P pixel ; Establishing a bending model based on the acquired bending feature points of the puncture needle;

[0196] Robot motion parameter determination module, used to obtain the puncture target point P target , read its pixel coordinates The coordinates in the robot coordinate system are obtained through imaging calibration relationship. Get the puncture point P entry , and determine the coordinates of the needle entry point in the robot coordinate system Based on the puncture target point P target , the puncture point P entry The bending model determines the robot motion parameters, including the puncture needle angle θ needle and the puncture needle insertion depth Deepth, so that the robot can carry the puncture needle through the needle insertion point P entry Arriving at the puncture target point P target ;

[0197] Alternatively, the degrees of freedom and the elongation of each axis of the robot carrying the puncture needle are obtained to determine the puncture needle angle θ. needle , the depth of the needle and the puncture point P entry Based on the bending model, the puncture needle carried by the robot is determined according to the puncture needle angle θ needle , the terminal end point P that can be reached by the needle insertion depth Deepth tip Coordinates in the robot coordinate system And the pixel coordinates in the medical image are obtained through imaging calibration relationship.

[0198] Furthermore, the puncture needle bending model determination module is also used to: establish a bending coordinate system with the needle insertion point as the origin, and determine the coordinates P of each bending feature point in the bending coordinate system. bend ; A spline curve is fitted to the path of the puncture needle in the curved coordinate system as a curved model.

[0199] Furthermore, the spline curve fitting specifically includes:

[0200] Randomly select k bending feature points from the K bending feature points of the puncture needle, select T groups in total, fit each group of bending feature points with an n-order polynomial spline curve, and add the fitted curve to the candidate set W;

[0201] Each curve in the candidate set W is evaluated, that is, for each curve, the average distance between the other Kk curved feature points in the group and the curve is calculated, and the curve corresponding to the minimum average distance is selected from the candidate set W, which is the best fitting curve C needle .

[0202] Furthermore, the best fitting curve C needle The choices are as follows:

[0203]

[0204] Among them, d j is the average distance between the jth group of Kk bending feature points and the curve, d m is the minimum average distance, C m is the curve corresponding to the minimum average distance.

[0205] Furthermore, in the puncture needle bending model determination module, the puncture needle is used to perform horizontal puncture on the soft tissue simulation body, and a bending coordinate system is established with the puncture point as the origin and the puncture direction as the x-axis. entry .

[0206] Furthermore, in the puncture needle bending model determination module, the puncture needle starts to bend from the insertion point, and the insertion direction is parallel to the x-axis of the bending coordinate system. The curve C after fitting based on the j-th group of bending feature points j The fitting curve is determined and the bending model is established by satisfying the following constraints:

[0207]

[0208] Furthermore, the robot motion parameter determination module is also used to: determine the conversion relationship between the robot coordinate system, the image coordinate system and the bending coordinate system through calibration; based on the puncture needle bending model, solve the robot's forward kinematics model or inverse kinematics model to determine the robot's motion parameters.

[0209] Furthermore, the robot motion parameter determination module is also used for:

[0210] Perform imaging calibration on the robot to determine the transformation relationship T from the robot coordinate system to the image coordinate system 1 ; The puncture target point P target Coordinates in the robot coordinate system With its pixel coordinates The relationship is:

[0211]

[0212] Determine the puncture point P on the surface of the soft tissue simulation entry , and the coordinates of the needle entry point in the robot coordinate system Assume the insertion angle of the puncture needle is θ needle , then the curved coordinate system O entry The origin is the needle insertion point P entry , the direction of its x-axis is the direction of needle insertion, and the angle between it and the x-axis of the robot coordinate system is θ needle ;

[0213] Assume that the transformation relationship from the robot coordinate system to the bending coordinate system is T 2 , then:

[0214]

[0215] According to the conversion relationship, the target point P target Coordinates in curved coordinate system It is expressed as:

[0216]

[0217] The target point is located on the curved path of the puncture needle, so its coordinates in the curved coordinate system satisfy the best fitting curve C of the curved model. needle :

[0218]

[0219] Solve to get the puncture angle θ needle , substitute it into T 2 Get the target point P target Coordinates in curved coordinate system

[0220] The length of the curved part of the puncture needle is the puncture depth Deepth, which is calculated by the scalar line integral of the best fitting curve of the bending model:

[0221]

[0222] According to the geometric relationship of the puncture mechanism model, the relationship between the puncture needle posture and the motor shaft state is determined, and the needle insertion angle θ needle , Needle insertion depth Deepth and needle insertion point position P entry Substituting into equation F, determine the elongation of each axis of the robot carrying the puncture needle.

[0223] Furthermore, the robot motion parameter determination module is also used to: determine the degrees of freedom and the elongation of each axis of the robot carrying the puncture needle, and bring them into the relationship F between the puncture needle posture and the motor shaft state determined according to the geometric relationship of the puncture mechanism model to determine the puncture needle angle θ needle , Needle insertion depth Deepth and needle insertion point P entry ;

[0224] The needle insertion point P entry The curved coordinate system O is established with the puncture needle direction as the x-axis. entry , then from the robot coordinate system O robot To the curved coordinate system O entry The conversion relationship T 2 for:

[0225]

[0226] The puncture needle enters the soft tissue simulation body from the origin and follows the best fitting curve C of the curved model. needle Bend, reach the end point P after reaching the needle insertion depth Deepth tip , let its coordinates in the curved coordinate system be Then the scalar line integral from the origin to the end point satisfies:

[0227]

[0228] Solving the above integral equation, we get Substitute it into the following formula to obtain

[0229]

[0230] Finally, through the coordinate system transformation relationship T 2 Solve to get the end point P of the puncture needle tip In the robot coordinate system O robot The coordinates below

[0231]

[0232] In an exemplary embodiment, the present invention further provides an electronic device, the electronic device comprising:

[0233] processor;

[0234] A memory having computer-readable instructions stored thereon, wherein when the computer-readable instructions are loaded and executed by the processor, the steps of the above-mentioned method for determining the motion parameters of the robot are implemented.

[0235] In an exemplary embodiment, the present invention further provides a computer-readable storage medium, wherein at least one instruction is stored in the computer-readable storage medium, and the at least one instruction is loaded and executed by a processor to implement the steps of the robot motion parameter determination method as described above. For example, the computer-readable storage medium can be a ROM, a random access memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, etc.

[0236] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

[0237] References in the specification to "one embodiment", "an embodiment", "an exemplary embodiment", "some embodiments", etc. indicate that the described embodiments may include a particular feature, structure, or characteristic, but not every embodiment may include the particular feature, structure, or characteristic. In addition, when a particular feature, structure, or characteristic is described in conjunction with an embodiment, it should be within the knowledge of a person skilled in the relevant art to implement such feature, structure, or characteristic in conjunction with other embodiments (whether or not explicitly described).

[0238] It should be understood that the term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship, but it may also indicate an "and / or" relationship. Please refer to the context for specific understanding.

[0239] In the present invention, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can be represented by: a, b, c, ab, ac, bc, or abc, where a, b, c can be single or multiple.

[0240] It should be understood that in various embodiments of the present invention, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0241] In the several embodiments provided by the present invention, it should be understood that the disclosed devices, apparatuses and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0242] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0243] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0244] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0245] The present invention covers any substitution, modification, equivalent method and scheme made on the essence and scope of the present invention. In order to make the public have a thorough understanding of the present invention, specific details are described in detail in the following preferred embodiments of the present invention, but those skilled in the art can fully understand the present invention without the description of these details. In addition, in order to avoid unnecessary confusion about the essence of the present invention, well-known methods, processes, procedures, components and circuits are not described in detail.

[0246] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for determining robot motion parameters based on a puncture needle bending model, characterized in that: The following steps are involved: S1. Puncture the soft tissue simulation body with a puncture needle, detect the medical image of the puncture needle in real time, select multiple points in the medical image as bending feature points of the puncture needle, the bending feature points include the needle insertion point, and record each bending feature point in the image coordinate system. pixel The pixel coordinates P pixel ; Establishing a bending model based on the acquired bending feature points of the puncture needle; S2. Obtain the puncture target point P target , read its pixel coordinates The coordinates in the robot coordinate system are obtained through imaging calibration relationship. Get the puncture point P entry , and determine the coordinates of the needle entry point in the robot coordinate system Based on the puncture target point P target , the puncture point P entry The bending model determines the robot motion parameters, including the puncture needle angle θ needle and the puncture needle insertion depth Deepth, so that the robot can carry the puncture needle through the needle insertion point P entry Arriving at the puncture target point P target ; Alternatively, the degrees of freedom and the elongation of each axis of the robot carrying the puncture needle are obtained to determine the puncture needle angle θ. needle , the depth of the needle and the puncture point P entry Based on the bending model, the puncture needle carried by the robot is determined according to the puncture needle angle θ needle , the terminal end point P that can be reached by the needle insertion depth Deepth tip Coordinates in the robot coordinate system And the pixel coordinates in the medical image are obtained through imaging calibration relationship.

2. The method for determining robot motion parameters based on a puncture needle bending model according to claim 1, characterized in that: The step S1 also includes the following steps: establishing a bending coordinate system with the needle insertion point as the origin, determining the coordinates P of each bending feature point in the bending coordinate system bend ; A spline curve is fitted to the path of the puncture needle in the curved coordinate system as a curved model.

3. The method for determining robot motion parameters based on a puncture needle bending model according to claim 2, characterized in that: The spline curve fitting step specifically includes: Randomly select k bending feature points from the K bending feature points of the puncture needle, select T groups in total, fit each group of bending feature points with an n-order polynomial spline curve, and add the fitted curve to the candidate set W; Each curve in the candidate set W is evaluated, that is, for each curve, the average distance between the other Kk curved feature points in the group and the curve is calculated, and the curve corresponding to the minimum average distance is selected from the candidate set W, which is the best fitting curve C needle .

4. The method for determining robot motion parameters based on a puncture needle bending model according to claim 3, characterized in that: Best fit curve C needle The choices are as follows: Among them, d j is the average distance between the jth group of Kk bending feature points and the curve, d m is the minimum average distance, C m is the curve corresponding to the minimum average distance.

5. The method for determining robot motion parameters based on a puncture needle bending model according to any one of claims 2 to 4, characterized in that: In step S1, the soft tissue simulation body is punctured horizontally using a puncture needle, and a curved coordinate system is established with the puncture point as the origin and the puncture direction as the x-axis. entry .

6. The method for determining robot motion parameters based on a puncture needle bending model according to claim 5, characterized in that: The puncture needle starts to bend from the insertion point, and the insertion direction is parallel to the x-axis of the bending coordinate system. The curve C fitted based on the jth group of bending feature points j The fitting curve is determined and the bending model is established by satisfying the following constraints:

7. The method for determining robot motion parameters based on a puncture needle bending model according to any one of claims 2 to 4, characterized in that: The step S2 also includes the following steps: determining the conversion relationship between the robot coordinate system, the image coordinate system and the bending coordinate system through calibration; solving the forward kinematics model or inverse kinematics model of the robot based on the bending model of the puncture needle to determine the motion parameters of the robot.

8. The method for determining robot motion parameters based on a puncture needle bending model according to claim 7, characterized in that: The step S2 further comprises the following steps: The robot is imaged and calibrated to determine the conversion relationship T1 from the robot coordinate system to the image coordinate system; the puncture target point P target Coordinates in the robot coordinate system With its pixel coordinates The relationship is: Determine the puncture point P on the surface of the soft tissue simulation entry , and the coordinates of the needle entry point in the robot coordinate system Assume the insertion angle of the puncture needle is θ needle , then the curved coordinate system O entry The origin is the needle insertion point P entry , the direction of its x-axis is the direction of needle insertion, and the angle between it and the x-axis of the robot coordinate system is θ needle ; Assume that the transformation relationship from the robot coordinate system to the bending coordinate system is T2, then: According to the conversion relationship, the target point P target Coordinates in curved coordinate system It is expressed as: The target point is located on the curved path of the puncture needle, so its coordinates in the curved coordinate system satisfy the best fitting curve C of the curved model. needle : Solve to get the puncture angle θ needle Substitute it into T2 to get the target point P target Coordinates in curved coordinate system The length of the curved part of the puncture needle is the puncture depth Deepth, which is calculated by the scalar line integral of the best fitting curve of the bending model: According to the geometric relationship of the puncture mechanism model, the relationship between the puncture needle posture and the motor shaft state is determined, and the needle insertion angle θ needle , Needle insertion depth Deepth and needle insertion point position P entry Substituting into equation F, determine the elongation of each axis of the robot carrying the puncture needle.

9. The method for determining robot motion parameters based on a puncture needle bending model according to claim 7, characterized in that: The step S2 further comprises the following steps: Determine the degrees of freedom and the elongation of each axis of the robot carrying the puncture needle, and substitute them into the relationship F between the puncture needle posture and the motor shaft state determined by the geometric relationship of the puncture mechanism model to determine the puncture needle angle θ needle , Needle insertion depth Deepth and needle insertion point P entry ; The needle insertion point P entry The curved coordinate system O is established with the puncture needle direction as the x-axis. entry , then from the robot coordinate system O robot To the curved coordinate system O entry The conversion relationship T2 is: The puncture needle enters the soft tissue simulation body from the origin and follows the best fitting curve C of the curved model. needle Bend, reach the end point P after reaching the needle insertion depth Deepth tip , let its coordinates in the curved coordinate system be Then the scalar line integral equation from the origin to the end point is: Solving the above scalar line integral equation, we get Substitute it into the following formula to obtain Finally, the end point P of the puncture needle is obtained by solving the coordinate system transformation relationship T2. tip In the robot coordinate system O robot The coordinates below 10. A robot motion parameter determination device based on a puncture needle bending model, characterized in that: The device comprises: The puncture needle bending model determination module is used to puncture the soft tissue simulation body with the puncture needle, detect the medical image of the puncture needle in real time, select multiple points in the medical image as the bending feature points of the puncture needle, and the bending feature points include the needle insertion point, and record each bending feature point in the image coordinate system O pixel The pixel coordinates P pixel ; Establishing a bending model based on the acquired bending feature points of the puncture needle; Robot motion parameter determination module, used to obtain the puncture target point P target , read its pixel coordinates The coordinates in the robot coordinate system are obtained through imaging calibration relationship. Get the puncture point P entry , and determine the coordinates of the needle entry point in the robot coordinate system Based on the puncture target point P target , the puncture point P entry The bending model determines the robot motion parameters, including the puncture needle angle θ needle and the puncture needle insertion depth Deepth, so that the robot can carry the puncture needle through the needle insertion point P entry Arriving at the puncture target point P target ; Alternatively, the degrees of freedom and the elongation of each axis of the robot carrying the puncture needle are obtained to determine the puncture needle angle θ. needle , the depth of the needle and the puncture point P entry Based on the bending model, the puncture needle carried by the robot is determined according to the puncture needle angle θ needle , the terminal end point P that can be reached by the needle insertion depth Deepth tip Coordinates in the robot coordinate system And the pixel coordinates in the medical image are obtained through imaging calibration relationship.

Images