Methods and apparatus for planning cutting paths for surgical robots

Abstract

This disclosure relates to a method and apparatus for planning a cutting path for a surgical robot. The method for planning a cutting path for a surgical robot includes: identifying implant planning information, the implant planning information including a planned implant placement position and orientation based on a virtual bone model corresponding to the target bone in the surgery; generating a cutting section of the bone model based on the implant planning information; selecting a standard cutting path corresponding to the cutting section of the bone model from one or more standard cutting paths pre-stored in a computing device; and generating a modified cutting path by modifying the selected standard cutting path based on the outer edge of the cutting section. Therefore, a patient-customized cutting path can be quickly planned based on pre-stored standard cutting paths.

Description

Technical Field

[0001] This disclosure relates to a technique for planning the cutting path of a surgical robot, and more specifically, to a method for planning the cutting path of a bone to be cut by a surgical robot during artificial joint replacement to place an implant, and an apparatus for performing the method. Background Technology

[0002] Robotic surgery can be broadly categorized into passive robotic surgery, semi-active robotic surgery, and active robotic surgery. Passive robotic surgery refers to a method where the surgeon manually operates the robot throughout the entire surgical procedure. Semi-active robotic surgery involves the surgeon using a robot to perform procedures such as cutting, but the robot uses tactile feedback or other methods to restrict the surgeon's movement of surgical instruments along predetermined paths. Active robotic surgery, on the other hand, involves a robot automatically performing surgery according to a planned cutting path without the surgeon's intervention.

[0003] As mentioned above, since the robot actively cuts the bone during active robotic surgery, it is very important to plan a cutting path suitable for the implant to be placed.

[0004] In related technologies, a library of cutting paths is prepared in advance, defining the cutting paths according to the shape or size of the implant. When the planner determines the shape and size of the implant to be placed on the target bone, a cutting path corresponding to the shape and size of the implant is selected from this library and used. This library-based cutting path fails to take into account the diversity of patients' bone shapes, thus limiting its ability to provide customized surgery for patients.

[0005] Furthermore, cutting paths are typically generated for areas slightly smaller than the implant shape and have a predetermined cutting allowance to prevent damage to soft tissue, resulting in a considerable area of ​​uncut residual bone. This residual bone area needs to be manually cut and finished by the surgeon, which not only causes inconvenience but also prolongs the operation time. The cutting allowance used to minimize the residual bone area varies depending on the specific location of the implant. However, considering all possible minimum cutting allowances corresponding to various implant locations, setting conventional library-based cutting paths is difficult, thus resulting in the problem of a relatively large residual bone area. Summary of the Invention

[0006] Technical issues This disclosure is conceived to address the problems of the aforementioned related technologies. One aspect of this disclosure is to provide a method and apparatus for planning the cutting path of a surgical robot, which can generate a patient-customized cutting path and minimize residual bone areas, taking into account the diversity of patient bone shapes.

[0007] Technical solution According to embodiments of this disclosure, a method for planning a cutting path for a surgical robot is provided. The method is executed by a computing device and includes: identifying implant planning information, the implant planning information including implant placement position and orientation planned based on a virtual bone model corresponding to a target bone; generating a cutting section of the bone model based on the implant planning information; selecting a standard cutting path corresponding to the cutting section of the bone model from one or more standard cutting paths pre-stored in the computing device; and generating a modified cutting path by modifying the selected standard cutting path based on the outer edge of the cutting section.

[0008] Here, generating the modified cutting path may include extending the standard cutting path toward the outer edge of the cutting section.

[0009] Meanwhile, the standard cutting path may include multiple unit cutting paths, and may include multiple path points corresponding to the start and end points of the unit cutting paths.

[0010] In this case, generating the modified cutting path may include generating the first modified cutting path by changing the length of one or more unit cutting paths.

[0011] Here, generating the first modified cutting path may include: identifying the intersection point between the extension line of the unit cutting path and the outer edge of the cutting section; determining the changed position of the path point based on the intersection point; and modifying the unit cutting path by applying the changed path point to the changed position.

[0012] Meanwhile, the method may also include identifying the maximum distance that the cutting tool can move continuously in a predetermined direction based on pre-stored information about the cutting tool of the surgical robot. In this case, determining the changed position of the path point may include considering the direction of movement of the cutting tool on the unit cutting path and the maximum distance of movement of the cutting tool to determine the changed position.

[0013] In this case, taking into account the pre-defined cutting allowance area for protecting the surrounding tissues of the target bone, the changed position of the path point is determined such that the changed position is not located within the pre-defined cutting allowance area.

[0014] Furthermore, generating the modified cutting path may also include: determining whether to further modify the first modified cutting path by comparing the area of ​​the cutting cross section with the area of ​​the cutting region predicted according to the first modified cutting path; and generating a second modified cutting path by increasing the number of unit cutting paths constituting the first modified cutting path based on the determination result.

[0015] Here, the method may further include identifying the maximum distance that the cutting tool of the surgical robot can move continuously in a predetermined direction in one step, based on pre-stored information about the cutting tool of the surgical robot. Generating the second modified cutting path may include: determining the location to add a new path point, considering the outer edge of the cutting section and the maximum distance of movement of the cutting tool; generating a new path point at the location; and adding a new unit cutting path to the first modified cutting path using the new path point.

[0016] In this case, determining the location where a new path point should be added may include preventing the path point from being added within a range that is less than or equal to a predetermined distance from the outer edge of the cut section.

[0017] In addition, determining the location to add a new path point may include determining the location as a position from an existing path point where the movement of the cutting tool in the predetermined direction does not exceed the movement limit distance.

[0018] According to another embodiment of this disclosure, an apparatus for planning a cutting path for a surgical robot is provided. The apparatus includes: a storage unit configured to store one or more standard cutting paths and implant planning information, the implant planning information including implant placement position and placement posture planned based on a virtual bone model corresponding to a target bone; and a processor configured to generate a cutting section of the bone model based on the implant planning information, select a standard cutting path corresponding to the cutting section of the bone model from the one or more stored standard cutting paths, and generate a modified cutting path by modifying the selected standard cutting path based on the outer edge of the cutting section.

[0019] Beneficial effects As described above, according to this disclosure, surgical outcomes can be further improved by automatically generating patient-customized cutting paths that take into account the diversity of patient bone shapes.

[0020] Furthermore, according to this disclosure, by expanding the cutting path based on a pre-stored standard cutting path, a patient-customized cutting path can be quickly planned.

[0021] Furthermore, according to this disclosure, a cutting path is generated to minimize the residual bone area left after the surgical robot cuts, thereby simplifying the surgical procedure and effectively preventing surgical delays. Attached Figure Description

[0022] Figure 1 This is a diagram illustrating a schematic configuration of an arthroplasty robotic surgical system including a device for planning the cutting path of a surgical robot according to an embodiment of the present disclosure.

[0023] Figure 2 This is a block diagram illustrating a detailed configuration of a device for planning a cutting path according to an embodiment of the present disclosure.

[0024] Figure 3 This is a flowchart illustrating a method for planning a cutting path for a surgical robot according to an embodiment of the present disclosure.

[0025] Figure 4A and Figure 4B This is a diagram illustrating a standard cutting path according to an embodiment of the present disclosure.

[0026] Figure 5 It is a diagram used to explain the concept of the maximum distance a cutting tool can move.

[0027] Figure 6 It shows Figure 3 The flowchart shows the detailed process of generating the first modified cutting path.

[0028] Figure 7 and Figure 8 The figures illustrate examples of modifying a standard cutting path without adding path points according to embodiments of the present disclosure.

[0029] Figure 9 It is used to explain in such Figure 8 The figure shows an example of determining the changed position of the path point when modifying the standard sawtooth cutting path.

[0030] Figure 10 It shows Figure 3 The flowchart shows the detailed process of generating the second modified cutting path.

[0031] Figure 11 and Figure 12 The figures illustrate examples of modifying a standard cutting path by adding new path points according to embodiments of the present disclosure.

[0032] Figure 13A and Figure 13B This is a diagram used to explain the method of adding vertical path points according to embodiments of the present disclosure. Detailed Implementation

[0033] In the following description, specific embodiments of the present disclosure will be described with reference to the accompanying drawings. However, in the following description and drawings, detailed descriptions of known functions or configurations that may obscure the gist of the present disclosure will be omitted. Furthermore, it should be noted that the same reference numerals are used to denote the same components as much as possible throughout the drawings.

[0034] The device for planning the cutting path of a surgical robot according to this disclosure plans the cutting path of the target bone to be cut by the surgical robot during artificial joint replacement to place the implant. Artificial joint replacements proposed herein include total knee replacement, partial knee replacement, and hip replacement. In the following description, total knee replacement will be used as an example.

[0035] Figure 1 This is a diagram illustrating a schematic configuration of an arthroplasty robotic surgical system 1, which includes a device for planning the cutting path of a surgical robot according to an embodiment of the present disclosure.

[0036] refer to Figure 1 The arthroplasty robotic surgical system 1 includes bone markers BM1 and BM2 fixed to target bones B1 and B2, a surgical robot 100, a tracking device 200, and a device for planning the cutting path of the surgical robot (hereinafter referred to as the cutting path planning device) 300.

[0037] Target bones B1 and B2 refer to the bones that are targeted in robotic surgery. Figure 1 Take femoral bone B1 and tibia B2 as examples. Bone markers BM1 and BM2 are fixedly installed on femoral bone B1 and tibia B2, respectively. Bone markers BM1 and BM2 are used as references to track the position of femoral bone B1 and tibia B2 during surgery.

[0038] Surgical robot 100 is a robot that performs joint replacement surgery, consisting of a robot base 101 and a robot arm 103. Various cutting tools 105 (including drills) for performing bone cutting can be coupled to an end effector at the end of the robot arm 103. Various types of tools can be used as cutting tools 105, such as milling cutters that perform cutting by rotational motion and saw blade cutters that perform cutting by translational motion.

[0039] Furthermore, the surgical robot 100 may be equipped with various sensors capable of sensing the state information of the surgical robot 100, such as the load applied to the cutting tool and the operating speed of the robot. A robot marker RM, serving as a reference for tracking the position of the surgical robot 100, is fixed on the base 101 of the surgical robot 100.

[0040] For reference, passive or active optical markers can be used as skeletal markers BM1 and BM2, as well as robotic markers RM. Optical markers comprise multiple branches in a branching manner, branching in different directions relative to a central point, and spherical markers can be formed at the ends of each branch. This is just one example of the shape of an optical marker; optical markers can be implemented in a variety of other known shapes.

[0041] The tracking device 200 is used to track the position and orientation of bone markers BM1 and BM2 fixed to target bones B1 and B2, and the position and orientation of robotic markers RM fixed to the surgical robot 100, and can be implemented as an optical tracking system (OTS). For reference, an optical tracking system refers to a device capable of tracking markers using two infrared cameras and determining their position and orientation in three-dimensional space in real time by calculating distances based on triangulation. Since the tracking principle of such an optical tracking system is widely known, its detailed description will be omitted.

[0042] The cutting path planning device 300 plans the cutting path of the surgical robot 100 for target bones B1 and B2, which need to be cut to place implants during joint replacement. Cutting path planning can be performed before robotic surgery or through planning modifications during surgery. The cutting path includes position and orientation information; the position information indicates the position the surgical robot 100 will move to as it moves along the cutting path from a starting point to an end point, and the orientation information indicates the orientation of the surgical robot 100 at the corresponding position. The cutting path, including the relative position and orientation information of the surgical robot 100, can be generated based on the implant coordinate system. For reference, the cutting path includes not only the path taken by the cutting tool 105 of the surgical robot 100 to directly cut the bone, but also the movement path of the surgical robot 100 as it approaches the bone to cut.

[0043] The cutting path planning device 300 can be implemented as a computing device, which includes a processor for planning the cutting path, a display for displaying the planned cutting path, and a memory for storing the generated cutting path information. Although Figure 1The cutting path planning device 300 is shown as physically separate from the surgical robot 100 and implemented as a separate device. However, in some cases, the processor and memory of the cutting path planning device 300 can be housed within the surgical robot 100, and the display can be connected to and installed with the tracking device 200, and various information can be sent and received via a communication module. Furthermore, as mentioned above, since cutting path planning can be performed even before surgery, the cutting path planning device 300 does not necessarily need to be located in the same space as the surgical robot 100 and tracking device 200 required during surgery, but can be located in a remote space. In this case, the cutting path data generated by the cutting path planning device 300 can be transmitted to the surgical robot 100 using various wired / wireless communication methods, allowing the surgical robot 100 to perform surgery according to the planned cutting path.

[0044] Figure 2 This is a block diagram illustrating a detailed configuration of a cutting path planning device 300 according to an embodiment of the present disclosure. (See reference...) Figure 2 The cutting path planning device 300 according to an embodiment of the present disclosure includes a user interface unit 310, a display unit 320, a storage unit 330, and a processor 340.

[0045] User interface unit 310 refers to a module used to receive various inputs from the user during the planning of the cutting path of surgical robot 100, and can be implemented using various input devices such as mouse, keyboard, keypad, button and remote control.

[0046] Display unit 320 is used to display various information, including images, graphics, and text, on a screen, and can be implemented as a liquid crystal display (LCD) panel, a light-emitting diode (LED) panel, an organic light-emitting diode (OLED) panel, etc. Furthermore, user interface unit 310 and display unit 320 can be integrated and implemented as a single device, such as a touchscreen. Display unit 320 displays various GUI and planning outputs provided during the planning of implant placement and orientation, as well as during the planning of the cutting path of surgical robot 100, including implant models, 2D images and 3D models of the target bone, and the cutting path of surgical robot 100.

[0047] Storage unit 330 is implemented as a storage device such as RAM, flash memory, or EPROM, and can store at least one computer program code executed by processor 340. Such computer program code can be loaded into storage unit 330 from floppy disk drives, disks, magnetic tapes, DVD / CD-ROM drives, memory cards, etc., which are separate from storage unit 330. In addition, storage unit 330 stores CT or MRI images of the patient captured before surgery, an implant library storing implant attribute information (e.g., implant type / shape / length / size), a pre-generated standard cutting path based on implant volume, information about the cutting tool (including the cutting characteristics of the cutting tool, such as the type of cutting tool mounted on the robotic arm of surgical robot 100, as well as the cutting depth, cutting width, and maximum distance of movement according to a predetermined direction), and various other reference information applied in the process of planning the cutting path of surgical robot 100.

[0048] The processor 340 executes program code stored in the device to perform a cutting path planning process for the surgical robot 100 based on pre-generated and pre-stored standard cutting paths for the target bone. That is, instead of generating the cutting path of the surgical robot 100 from scratch, the processor 340 plans the cutting path of the surgical robot 100 by modifying the pre-stored standard cutting path corresponding to the target bone.

[0049] In the following text, reference will be made to Figures 3 to 1 3. A method for planning the cutting path of a surgical robot, performed by the cutting path planning device 300.

[0050] Figure 3 This is a flowchart illustrating a method for planning a cutting path for a surgical robot according to an embodiment of the present disclosure.

[0051] refer to Figure 3 Assume that standard cutting path data and information about the cutting tool are stored in the cutting path planning device 300 (S100). A standard cutting path is a pre-generated cutting path based on the bone shape of the implant rather than a specific patient, to be broadly applicable to the target bone of various patients. The standard cutting path is pre-generated by taking into account the characteristics of each implant (e.g., implant type, shape, and size) and the cutting surface to be treated. The standard cutting path is typically generated within the implant volume, except for the portion of the entire path corresponding to the initial entry path where the surgical robot 100 approaches the bone to make the cut. This is to confine the actual cutting area within the implant volume to protect soft tissues such as ligaments, blood vessels, muscles, and skin.

[0052] Figure 4A and Figure 4BThis is a diagram illustrating a standard cutting path according to an embodiment of the present disclosure.

[0053] refer to Figure 4A and Figure 4B The standard cutting paths 410 and 420 consist of multiple unit cutting paths SL and include multiple path points P corresponding to the start and end points of each unit cutting path SL.

[0054] also, Figure 4A and Figure 4B Examples of standard cutting paths 410 and 420, each consisting of two local cutting paths targeting a single cutting surface of the bone, are shown. That is, Figure 4A A standard cutting path 410, consisting of a first local cutting path 410a and a second local cutting path 420a, is shown. Figure 4B A standard cutting path 420, consisting of a first local cutting path 410b and a second local cutting path 420b, is shown. Thus, the standard cutting path can be generated as a single path targeting a cutting surface of the target bone, but it can also include two or more separate local cutting paths targeting a cutting surface. Furthermore, path points P are points located on the cutting path, and in addition to the start point PS and end point PE of the cutting path or each local cutting path, each path point P is a connection point between two unit cutting paths SL, and corresponds to a direction change point where the direction of the cutting tool 105 changes.

[0055] Figure 4A An example of a standard cutting path 410 is shown, consisting of horizontal, vertical, and diagonal cutting paths SL that are perpendicular to each other. Specifically, Figure 4A A standard cutting path is shown, consisting of a first unit cutting path SL1 (cutting by the cutting tool moving horizontally), a second unit cutting path SL2 (cutting by the cutting tool moving vertically), and a third unit cutting path SL3 (cutting by the cutting tool 105 moving diagonally (including both horizontal and vertical components)). Meanwhile, Figure 4B A zigzag standard cutting path is shown, consisting of diagonal element cutting paths SL that simultaneously include horizontal and vertical components. It should be noted that directions such as horizontal, vertical, and diagonal do not necessarily represent the direction of the element cutting path itself based on the planting coordinate system, but rather the direction in which the cutting tool moves along the corresponding element cutting path, as defined by the cutting tool.

[0056] Despite passing Figure 4A and Figure 4BTwo types of standard cutting paths are illustrated, but standard cutting paths are not limited to these and can be provided in various forms depending on the type of target bone (such as the tibia or femur), the location of the cutting surface on the target bone (such as the anterior or posterior region), and the type or size of the implant to be placed. For example, Figure 4B The example illustrates a zigzag standard cutting path 420 composed solely of diagonal unit cutting paths. However, alternatively, a zigzag standard cutting path can also be composed of two parallel unit cutting paths and a unit cutting path connecting these two diagonally. Thus, the standard cutting path can be composed of various forms, including a combination of a first unit cutting path where the surgical robot's cutting tool moves horizontally along a corresponding path, a second unit cutting path where the cutting tool moves longitudinally, or a third unit cutting path where the cutting tool moves diagonally, including both horizontal and longitudinal components.

[0057] One or more pre-generated standard cutting paths can be categorized into various classes based on the location of the implant and / or cutting surface, and stored in the form of a library.

[0058] Additionally, information about the cutting tool may include cutting characteristics such as the type of cutting tool, the diameter and size of the cutting tool, the cutting depth and the cutting width, and in particular, may include the maximum distance that the cutting tool can move continuously in a specific direction in a single operation.

[0059] Figure 5 It is a diagram used to explain the concept of the maximum distance a cutting tool can move.

[0060] For a cutting tool, the maximum distance it can move continuously in a specific direction—that is, the distance it can move for each operation in a specific direction (or a specific directional component)—is determined by the type of cutting tool. In this case, even for the same type of cutting tool, the specific value of the maximum distance can vary depending on the diameter or size of the cutting tool.

[0061] Figure 5 The diagram illustrates the movement characteristics of the cutting tool 105, where (a) shows a milling cutter 105a and (b) shows a saw blade cutter 105b. First, referring to (a), when performing a cut, the distance that the milling cutter 105a can move continuously in one continuous movement relative to the longitudinal direction (or longitudinal component) D2 defined by the milling cutter 105a is limited. Therefore, even when the milling cutter 105a performs a cut while moving along a diagonal direction including the horizontal component D1 and the longitudinal component D2, the milling cutter 105a is constrained by the limit distance of movement in the longitudinal direction D2.

[0062] On the other hand, there is a limitation on the distance that the saw blade cutter 105b can move continuously in the horizontal direction D1. Therefore, even if the saw blade cutter 105b cuts while moving in the diagonal direction, the saw blade cutter 105 is still constrained by the limit distance of movement in the horizontal direction D1.

[0063] Due to the movement limit distance in a specific direction (or direction component) caused by the type of cutting tool, it is very important to plan the cutting path so that the movement distance of the cutting tool in a specific direction, that is, the movement distance of the cutting tool in the unit cutting path corresponding to that specific direction, does not exceed the movement limit distance, which will be described later.

[0064] Subsequently, implant planning information regarding the implant to be placed on the target bone is identified (S200). This implant planning information can be generated based on a virtual 3D bone model corresponding to the target bone for a specific patient, and includes information about the placement position and orientation of the implant on the bone model. Here, the placement orientation refers to the angle or direction at which the implant is placed. The bone model of the target bone is a 3D model reconstructed preoperatively based on the patient's medical images (e.g., CT images, MRI images, etc.).

[0065] The placement position and orientation of the implant can be determined based on user input via the user interface unit 310. When the user selects an implant to be placed on the target bone from the implant library, the processor 340 generates a virtual model of the selected implant and overlays it onto the 3D bone model. Furthermore, the processor 340 can determine the appropriate placement position and orientation, such as the implant placement angle, based on the user's input of moving the virtual implant model on the 3D bone model via the user interface unit 310.

[0066] Furthermore, as mentioned above, the determination of the implant placement location and orientation does not necessarily depend entirely on user input, but can be performed automatically based on preset implant placement standards. For example, the processor 340 can identify the location, shape, and size of predetermined landmarks in a 3D skeletal model, and, based on implant placement standard information, determine the implant type and its appropriate placement location and orientation in response to the identification results. Implant planning information input by the user or determined by the processor 340 can be stored and loaded.

[0067] As described above, when implant planning information regarding the placement position and orientation of the implant is identified, a cutting section of the bone model is generated based on the implant planning information (S300). Here, the cutting section refers to a section generated by virtually cutting the surface that needs to be cut for joint surgery in the bone model corresponding to the pre-cut state. Although no actual cutting is performed, the processor 340 generates the cutting section in the bone model by predicting the post-cut state based on the 3D model of the target bone in the pre-cut state. The processor 340 can generate the cutting section by predicting the state in which the corresponding cutting surface has been cut according to the characteristics of the implant to be placed on the target bone (e.g., the placement position and orientation of the implant) based on the implant planning information, the shape and size of the implant, and the cutting characteristics (e.g., single cutting depth and cutting width) of the cutting tool used to perform the cutting.

[0068] Once the cutting section is generated, the outer edge of the generated cutting section is detected (S400). The outer edge, as the outermost boundary of the cutting section, can be detected based on various rule-based detection algorithms or deep learning-based algorithms. Rule-based detection algorithms are used to identify line information based on the shape, color, etc. of the objects displayed in the image. Deep learning-based algorithms are trained to detect the outer edge from the cutting section using convolutional neural networks (CNN), R-CNN, YOLO, etc.

[0069] Subsequently, the processor 340 selects a standard cutting path corresponding to the cutting section of the bone model from one or more standard cutting paths pre-stored in the cutting path planning device 300 (S500). The selection of the standard cutting path can be made by taking into account the type and size of the implant, as well as the position and shape of the cutting section, based on the implant planning information.

[0070] For example, the selection criteria for choosing a standard cutting path can be preset based on the location of each cutting section and / or the type or size of the implant, and the processor 340 can select a standard cutting path based on the preset criteria, or it can select a standard cutting path input through the user interface unit 310. Alternatively, a standard cutting path frequently used in previous robotic surgeries can be selected based on surgical information history.

[0071] Thus, when a standard cutting path is selected, the next step is to generate a modified cutting path by modifying the selected standard cutting path (S600). As mentioned above, since the standard cutting path is usually generated within the implant volume, the modification of the standard cutting path is performed by extending the standard cutting path towards the outer edge of the cutting section. The extension of the standard cutting path is performed to expand the cutting area, and as will be described later, the extension of the standard cutting path can be performed by extending the length of the unit cutting path without adding path points that constitute the standard cutting path, or by adding path points to add a new unit cutting path.

[0072] In this regard, the processor 340 first generates a first modified cutting path by changing the length of one or more cell cutting paths that constitute the standard cutting path, so as to generate a modified cutting path based on the standard cutting path (S610). The first modified cutting path refers to the cutting path generated by the standard cutting path by changing the length of one or more cell cutting paths by changing the position of existing path points without increasing the number of existing path points that constitute the standard cutting path.

[0073] For reference, since the modification of the standard cutting path is mainly to expand the cutting area to reduce the residual bone area left after the surgical robot 100 cuts, the movement path in the standard cutting path that does not perform substantial cutting (such as the entry path part where the surgical robot 100 approaches the target bone to cut) does not need to be modified.

[0074] Figure 6 It shows Figure 3 A flowchart detailing the process of generating the first modified cutting path step S610 is provided. Figure 7 and Figure 8 This is a diagram illustrating the process of generating a first modified cutting path according to an embodiment of the present disclosure. Reference will now be made to... Figures 6 to 8 Describe the process of generating the first modified cutting path based on the standard cutting path.

[0075] refer to Figure 6 The processor 340 identifies the intersection point between the extension line of each unit cutting path that constitutes the standard cutting path and the outer edge of the cutting section (S611).

[0076] Subsequently, based on these intersections, the changed positions of one or more existing path points of the standard cutting path are determined (S613). In this case, the changed positions are determined based on the movement direction of the cutting tool on the corresponding unit cutting path where each existing path point was located before the change, as well as the movement limit distance information of the cutting tool.

[0077] The processor 340 applies the path point whose position has been changed to the changed position determined in step S613 to modify the existing cell cutting path, thereby generating the first modified cutting path (S615).

[0078] Figure 7 and Figure 8 The figures shown are examples of modifying a standard cutting path without adding waypoints. Figure 7 Modifications are shown Figure 4A The example shown is a standard cutting path 410, mainly composed of horizontal and vertical unit cutting paths. Figure 8 Modifications are shown Figure 4B The example shown is a zigzag standard cutting path 420. For reference, in... Figure 7 and Figure 8 In this context, it is assumed that the movement of the cutting tool is limited to a predetermined range of longitudinal movement distances.

[0079] First, refer to Figure 7 The existing path points 710 to 720 and 730 to 735 are respectively changed to positions 710' to 720' and 730' to 735' corresponding to the intersections between the extension of the element cutting path SL and the outer edge ML of the cutting section. Therefore, the length of the element cutting path SL is extended, and the standard cutting path generally extends towards the outer edge ML of the cutting section. In this case, the extension of the element cutting path, in which the cutting tool moves horizontally along the corresponding element cutting path, can be performed in the direction in which the cutting tool moves from the inside to the outside of the target bone, i.e., towards the outer edge ML of the cutting section.

[0080] For reference, regarding Figure 7 In the first local cutting path 410a, the lower path, including path points 710 to 718, is defined in the planting coordinate system, with the X-axis corresponding to the longitudinal movement of the cutting tool and the Y-axis corresponding to the horizontal movement of the cutting tool. Regarding the upper path of the first local cutting path 410a, including path points 719 and 720, the X-axis corresponds to the horizontal movement of the cutting tool, and the Y-axis corresponds to the longitudinal movement of the cutting tool. Conversely, regarding the second local cutting path 410b, the X-axis corresponds to the horizontal movement of the cutting tool, and the Y-axis corresponds to the longitudinal movement of the cutting tool.

[0081] In this case, for the corresponding element cutting path SL where the horizontal movement of the cutting tool is unrestricted, its length can extend to the outer edge ML of the cutting section. On the other hand, for the corresponding element cutting path SL where the cutting tool moves longitudinally, its extension is limited because the element cutting path SL cannot exceed the preset longitudinal movement limit distance value of the cutting tool. Here, the longitudinal movement of the cutting tool includes diagonal movement comprising a longitudinal component. (Reference) Figure 7 For example, when the movement of the cutting tool on the element cutting path SL is performed in the longitudinal direction or includes a longitudinal movement component, such as the element cutting path SL connecting path points 711 and 712, the element cutting path SL connecting path points 713 and 714, the element cutting path SL connecting path points 715 and 716, or the element cutting path SL connecting path points 717 and 718, the amount of movement of the cutting tool is constrained by the movement limit distance. Therefore, the position change of the path points is performed with restrictions, so that the amount of movement in the longitudinal component can be kept within the movement limit distance range.

[0082] Next, refer to Figure 8 The standard cutting path 420 has a serrated shape, which is consistent with... Figure 7 Different, but with basic extended concepts and references. Figure 7 The descriptions are the same.

[0083] Because of the composition Figure 8 Each unit cutting path SL of the standard cutting path 420 is diagonal, so each unit cutting path SL essentially includes both horizontal and vertical movement components of the cutting tool. Therefore, when the length of the diagonal unit cutting path SL is extended, the position of the path point is changed, causing the vertical component movement to exist within the movement limit distance range of the cutting tool.

[0084] In other words, reference Figure 8 While satisfying the movement limit distance condition of the longitudinal component of the cutting tool, the positions of the existing path points 810 to 820 and 830 to 836 are changed to positions 810' to 820' and 830' to 836' respectively, corresponding to the intersection between the extension of the unit cutting path SL and the outer edge ML of the cutting section. Therefore, the length of the unit cutting path SL is extended, resulting in the standard cutting path being extended as a whole towards the outer edge ML of the cutting section.

[0085] Figure 9 It is used to explain the modification, such as Figure 8 The diagram shows an example of determining the changing position of path points when using a standard sawtooth cutting path. Figure 9The path shown is a portion of the cutting path, in which, based on the planting coordinate system, the Y-axis direction corresponds to the longitudinal movement of the cutting tool. Furthermore, it is assumed that the movement of the cutting tool in the longitudinal direction is limited to a predetermined limit distance.

[0086] refer to Figure 9 A virtual straight line 907 is generated between the midpoint 905 of the first path point 901 and the second path point 902, which are related to the longitudinal movement of the cutting tool, and the existing third path point 903, which corresponds to the intersection of the two existing unit cutting paths pSL. Furthermore, the intersection of the straight line 907 with the outer edge ML of the cutting section, or a point at a predetermined distance from this intersection into the bone for soft tissue protection, can be determined as the new modified position 903' of the existing path point 903. In this way, the standard cutting path can be extended while satisfying the movement limit distance condition of the longitudinal movement of the cutting tool.

[0087] For reference, as mentioned above, the intersection of the extension line of each unit cutting path and the outer edge of the cutting section can be directly determined as the changed position of the path point. However, considering the preset cutting allowance area, the changed position of the path point can also be determined as the position at a predetermined distance from the intersection point into the bone.

[0088] Here, the cutting allowance area refers to the area excluded from cutting to protect soft tissue, and can be defined as the area extending from the outer edge ML of the cutting section towards the interior of the target bone at a predetermined distance. A preset value can be applied for the distance into the bone, and different values ​​can be set depending on the type of cutting tool. Therefore, the processor 340 extends the standard cutting path towards the outer edge ML of the cutting section, but can determine the altered position so that the altered position of the path point is not located within the preset cutting allowance area.

[0089] As described above, after completing the initial modification process of altering the standard cutting path by changing the length of the unit cutting path without increasing the number of path points, the processor 340 compares the area of ​​the predicted cutting region based on the first modified cutting path generated through the above process with the area of ​​the cutting section of the bone model to determine whether additional modification is needed (S620). For reference, when predicting the cutting region based on the first modified cutting path, paths traversed by the cutting tool but not substantially cutting, or paths redundantly traversed by the cutting tool after cutting and moving to the next cutting position, are excluded from the cumulative calculation when predicting the cutting region.

[0090] If the area of ​​the cutting region predicted based on the first modified cutting path is smaller than the area of ​​the cutting section, or if the difference between the two is greater than a preset value, the processor 340 can modify the first modified cutting path by adding new path points, thereby generating a second modified cutting path (S630). In other words, the second modification modifies the standard cutting path by adding new path points to increase the number of unit cutting paths.

[0091] Figure 10 It shows Figure 3 A flowchart detailing the process of generating the second modified cutting path step S630 is provided. Figures 11 to 1 Figure 3 illustrates the process of generating a second modified cutting path according to an embodiment of the present disclosure. Reference will now be made to... Figures 10 to 1 3. Describe the process of generating the second modified cutting path.

[0092] First, refer to Figure 10 The processor 340 considers the outer edge of the cutting section of the skeleton model and the movement limit distance according to the predetermined direction of the cutting tool to determine the location where the new path point will be added (S631). In this case, taking into account the aforementioned cutting allowance area, the processor 340 can prevent the generation of new path points within a predetermined distance from the outer edge of the cutting section.

[0093] Subsequently, a new path point is generated at the determined location (S633), and a new unit cutting path is added to the first modified cutting path using the generated new path point (S635).

[0094] Figure 11 and Figure 12 The figures shown are examples of modifying a standard cutting path by adding new waypoints. Figure 11 It shows the example of Figure 7 The example described is a modification of the standard cutting path, which is mainly composed of horizontal and vertical unit cutting paths. Figure 12 It shows the example of Figure 8 An example of modifying the aforementioned zigzag standard cutting path. Figure 11 and Figure 12 Similarly, it is assumed that the movement of the cutting tool is limited to a predetermined limit distance in the longitudinal direction. For reference, newly added path points are indicated by * to distinguish them from existing path points.

[0095] exist Figure 11 and Figure 12 In the diagram, (a) shows the first modified cutting path, which has undergone an initial modification of changing the length of the cell cutting path relative to the standard cutting path, and (b) shows the state of generating the second modified cutting path by adding new cell cutting paths based on newly added path points.

[0096] Similar to changing the position of a path point, when a new path point is added, it is added at the following position: from the immediately preceding existing path point, the distance moved by the cutting tool in the predetermined direction (or direction component) does not exceed the preset movement limit distance.

[0097] according to Figure 11 and Figure 12 In one embodiment, when adding a new path point, the processor 340 can first add a longitudinal path point to be located on the longitudinal movement line of the cutting tool, which is constrained by the movement limit distance. Then, based on the added longitudinal path point, it can add a horizontal path point to be located on the horizontal movement line of the cutting tool. Simultaneously, the addition of both the longitudinal and horizontal path points is performed at locations not exceeding the outer edge boundary of the cutting section.

[0098] In this regard, first refer to Figure 11 In the cutting path of (a), since it is not possible to further extend the cutting path by simply changing the length of the cell cutting path SL, the cutting path is extended by adding path points.

[0099] When adding new path points 1101 to 1108, it is important that for new path points located on a longitudinal movement line where the movement of the cutting tool is restricted, the amount of movement of the cutting tool from the existing path point does not exceed a preset movement limit distance. As an example of generating new path points, processor 340 first adds 1101, 1103, 1104, and 1108 corresponding to the new path points on the longitudinal movement line, such that the amount of movement of the cutting tool from the immediately preceding existing path point does not exceed a preset movement limit distance. Subsequently, processor 340 generates virtual lines from 1101, 1103, 1104, and 1108 toward the outer edge ML of the cutting surface, and generates new path points 1102, 1105, 1106, and 1107 based on the intersections between the virtual lines and the outer edge ML of the cutting section. A new unit cutting path nSL is generated by connecting the new path points 1101 to 1108.

[0100] For reference, reference numerals "1102" and "1105" are new path points included in a new unit cutting path nSL, in which the cutting tool advances diagonally, including horizontal and longitudinal movement components, starting from the immediately preceding path point. These path points are constrained by a preset limit distance for the longitudinal movement component of the cutting tool. However, since the longitudinal movement limit distance was already considered when adding path points 1103 and 1108, path points 1102 and 1105, which are located on the same horizontal movement path of the cutting tool as path points 1103 and 1108, will not exceed the longitudinal movement limit distance of the cutting tool.

[0101] Figure 13A and Figure 13B This is a diagram illustrating a method for adding longitudinal path points according to an embodiment of the present disclosure.

[0102] First, refer to Figure 13A A virtual straight line 1301 is generated that extends the previous longitudinal element cutting path pSL in the existing element cutting path. One or more new longitudinal path points 1302 and 1303 located on the longitudinal movement line can be added at intervals on the straight line 1301 so as not to exceed the movement limit distance of the cutting tool.

[0103] Alternatively, as described above, a vector direction corresponding to the longitudinal direction in the planting coordinate system can be used instead of generating a virtual straight line 1301. That is, referencing Figure 13B A new longitudinal path point 1309 can be added from the immediately preceding path point 1307 on the longitudinal movement line of the existing path points, at a distance not exceeding the movement limit distance, in the vector direction corresponding to the longitudinal direction in the planting coordinate system.

[0104] As mentioned above, there may be several ways to add longitudinal path points, but all of these methods are the same in that they generate horizontal path points on the horizontal movement line based on the intersection between the virtual horizontal movement line of the cutting tool starting from the newly added longitudinal path point and the outer edge of the cutting section.

[0105] Additionally, adding new path points within a zigzag cutting path can also be done with reference. Figure 11 It is executed in the same manner as described.

[0106] In other words, for such Figure 12 In the zigzag cutting path, since each unit cutting path has a diagonal direction including the horizontal movement component and the longitudinal movement component of the cutting tool, it is necessary to generate new path points so that the longitudinal movement component does not exceed the movement limit distance of the cutting tool.

[0107] Therefore, when in Figure 12 When adding a new path point in a zigzag cutting path, the position of the new path point is determined such that the magnitude of the longitudinal movement component from the immediately preceding path point to the new path point is limited within the preset movement limit distance of the cutting tool, while the magnitude of the horizontal movement component is not particularly limited as long as it does not cross the outer edge boundary of the cutting section or (if applicable) the boundary of the preset cutting allowance area.

[0108] Simultaneously, if the distance exceeds the cutting tool's movement limit when generating a new unit cutting path by connecting existing path points and adjacent new path points, additional path points can be generated in between. For example, if in Figure 12If a new element cutting path nSL is generated by connecting existing path point 1208 and new path point 1210 in the cutting path, and the moving distance corresponding to the longitudinal component of the cutting tool exceeds the moving limit distance of the cutting tool, then the processor 340 can modify the cutting path so that it generates the new element cutting path nSL by adding a new path point 1209 at the middle position, instead of by connecting path points 1208 and 1210.

[0109] The above Figure 3 Steps S300 to S600 indicate that they are performed for a single cutting section, and if there are multiple cutting sections, steps S300 to S600 are repeated for each cutting section.

[0110] The cutting path planning device 300 can store the final cutting path that has been modified and display it through the display unit 320, thereby allowing users to verify the final cutting path.

[0111] As described above, according to this disclosure, by planning a cutting path customized for the target bone based on modifications to a standard cutting path, surgical planning can be established more effectively compared to planning the cutting path from scratch. Furthermore, the area of ​​residual bone remaining after the surgical robot cuts can be minimized, thereby simplifying the surgical procedure and effectively preventing surgical delays.

[0112] When executed on a computer, this disclosure can also be implemented as a variety of computer-readable recording media, such as magnetic storage media, optical reading media, and digital storage media, wherein a computer program is stored for performing a method for planning a cutting path for a surgical robot according to this disclosure.

[0113] Although several embodiments of this disclosure have been described, those skilled in the art will understand that various modifications and substitutions can be made to some embodiments without departing from the technical spirit of this disclosure. Therefore, the scope of protection of this disclosure should be interpreted as extending to the appended claims and their equivalents.

Claims

1. A method for planning a cutting path for a surgical robot, the method being performed by a computing device, the method comprising: Identify implant planning information, which includes the implant placement position and orientation planned based on a virtual bone model corresponding to the target bone; The cutting section of the bone model is generated based on the implant planning information; From one or more standard cutting paths pre-stored in the computing device, select the standard cutting path corresponding to the cutting section of the bone model; as well as The modified cutting path is generated by modifying the selected standard cutting path based on the outer edge of the cutting section.

2. The method according to claim 1, wherein, The process of generating the modified cutting path includes extending the standard cutting path toward the outer edge of the cutting section.

3. The method according to claim 1, wherein, The standard cutting path includes multiple unit cutting paths, and includes multiple path points corresponding to the start and end points of the unit cutting paths.

4. The method according to claim 3, wherein, The generation of the modified cutting path includes generating the first modified cutting path by changing the length of one or more unit cutting paths.

5. The method according to claim 4, wherein, The generation of the first modified cutting path includes: Identify the intersection point between the extension line of the unit cutting path and the outer edge of the cutting section; Determine the changed position of the path point based on the intersection point; and The cell cutting path is modified by applying the path points whose positions have been changed to the changed positions.

6. The method of claim 5, further comprising identifying, based on pre-stored information about the cutting tool of the surgical robot, the maximum distance that the cutting tool can move continuously in a predetermined direction in a single movement. in, Determining the changed position of the path point includes considering the direction of movement of the cutting tool on the unit cutting path and the maximum distance of movement of the cutting tool to determine the changed position.

7. The method according to claim 5, wherein, Taking into account a pre-defined cutting allowance area to protect the surrounding tissues of the target bone, the changed position of the path point is determined such that the changed position is not located within the pre-defined cutting allowance area.

8. The method according to claim 4, wherein, The generation of the modified cutting path also includes: By comparing the area of ​​the cut cross-section with the area of ​​the cut region predicted based on the first modified cut path, it is determined whether the first modified cut path needs to be further modified; and Based on the determined results, a second modified cutting path is generated by increasing the number of unit cutting paths constituting the first modified cutting path.

9. The method of claim 8, further comprising identifying, based on pre-stored information about the cutting tool of the surgical robot, the maximum distance that the cutting tool of the surgical robot can move continuously in a predetermined direction in one stroke. in, The generation of the second modified cutting path includes: Considering the outer edge of the cutting section and the maximum movement distance of the cutting tool, determine the location to add the new path point; A new waypoint is generated at the added location; and Use the new path point to add a new unit cutting path to the first modified cutting path.

10. The method according to claim 9, wherein, The determination of the location to add a new path point includes preventing the path point from being added within a range that is less than or equal to a predetermined distance from the outer edge of the cutting section.

11. The method according to claim 9, wherein, The determination of the location to add a new path point includes determining the location as a position where, starting from an existing path point, the movement of the cutting tool in the predetermined direction does not exceed the movement limit distance.

12. An apparatus for planning the cutting path of a surgical robot, the apparatus comprising: The storage unit is configured to store one or more standard cutting paths and implant planning information, the implant planning information including the implant placement position and placement posture planned based on a virtual bone model corresponding to the target bone; as well as processor, The processor is configured to: The cutting section of the bone model is generated based on the implant planning information; From the one or more stored standard cutting paths, select the standard cutting path that corresponds to the cutting section of the bone model; as well as The modified cutting path is generated by modifying the selected standard cutting path based on the outer edge of the cutting section.

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