Method and apparatus for planning cutting path for surgical robot

Abstract

The present invention relates to a method and an apparatus for planning a cutting path of a surgical robot. The method for planning a cutting path of a surgical robot, according to the present invention, comprises the step of: identifying implant planning information, including the planned implant placement position and orientation, with respect to a virtual bone model corresponding to a surgical target bone; generating a cut surface of the bone model on the basis of the implant planning information; selecting a standard cutting path corresponding to the cut surface of the bone model from among one or more standard cutting paths pre-stored in a computing device; and generating a corrected cutting path by correcting the selected standard cutting path on the basis of the outer line of the cutting surface. Therefore, a patient-customized cutting path can be quickly planned on the basis of the pre-stored standard cutting paths.

Description

Cutting path planning method and device for a surgical robot

[0001] The present invention relates to a cutting path planning technology for a surgical robot, and more specifically, to a method for planning a cutting path for a surgical target bone to be cut by a surgical robot in order to install an implant during artificial joint replacement surgery using a surgical robot, and to a device for performing the same.

[0002]

[0003] Robotic surgery can be broadly categorized into passive, semi-active, and active robotic surgery. Passive robotic surgery is a method in which the surgeon directly operates the robot throughout the entire surgical process. In semi-active robotic surgery, the surgeon uses the robot to perform procedures such as cutting, but during the process, the robot plays a role in limiting the movement of the surgical tools to a predetermined path through haptic feedback. Meanwhile, active robotic surgery is a method in which the robot automatically performs the surgery according to a planned cutting path without the surgeon's intervention.

[0004] As above, in active robotic surgery, the robot actively cuts the bone, so it is important to plan a cutting path that is suitable for the implant to be installed.

[0005] Conventional techniques typically involve pre-establishing a library of cutting paths based on implant shape and size. Once the planner determines the shape and size of the implant to be installed in the target bone, the planner selects and utilizes a cutting path corresponding to the implant shape and size from the library. This library-based cutting path fails to account for the variability in bone shape across patients, limiting its ability to provide personalized surgery.

[0006] In addition, in order to prevent damage to soft tissue, a cutting path is usually created for an area slightly smaller than the implant shape with a certain cutting margin. However, this results in a significant amount of residual bone remaining uncut. This residual bone area requires the surgeon to go through an additional process of cutting and final trimming, which not only causes inconvenience but also delays the surgical time. The cutting margin to minimize the residual bone area varies depending on the specific location of the implant, but it is difficult for the conventional library-based cutting path to be set by considering all cases of the minimum cutting margin according to the locations of various implants, resulting in the problem of a large amount of residual bone remaining.

[0007]

[0008] The present invention has been devised to solve the problems of the prior art as described above, and the purpose of the present invention is to provide a method and device for planning a cutting path of a surgical robot that can create a patient-tailored cutting path that takes into account the diversity of bones of each patient and minimize the residual bone area.

[0009]

[0010] The above object can be achieved by a cutting path planning method for a surgical robot, in which each step is performed by a computing device according to one aspect of the present invention, the method comprising: a step of confirming implant planning information including a planned implant installation position and posture for a virtual bone model corresponding to a bone to be operated on; a step of generating a cutting plane of the bone model based on the implant planning information; a step of selecting a standard cutting path corresponding to the cutting plane of the bone model from among one or more standard cutting paths pre-stored in the computing device; and a step of generating a modified cutting path by modifying the selected standard cutting path based on an outline of the cutting plane.

[0011] Here, the step of generating the above-described modified cutting path can extend the above-described standard cutting path toward the outer line of the above-described cutting plane.

[0012] Meanwhile, the above standard cutting path is composed of a plurality of unit cutting paths, and may include a plurality of path points corresponding to the start point and end point of each unit cutting path.

[0013] At this time, the step of generating the modified cutting path may include a step of generating a first modified cutting path by changing the length of one or more of the unit cutting paths.

[0014] Here, the step of generating the first modified cutting path may include: a step of recognizing an intersection of an extension line of the unit cutting path and an outer line of the cutting plane; a step of determining a changed position of the path point based on the intersection; and a step of modifying the unit cutting path by applying the path point whose position has been changed to the changed position.

[0015] Meanwhile, the step of determining a movement limit distance that the cutting tool can continuously move in a predetermined direction at one time through information stored in advance regarding the cutting tool of the surgical robot is further included, and the step of determining a change position of the path point can determine the change position by considering the movement direction of the cutting tool on the unit cutting path and the movement limit distance of the cutting tool.

[0016] At this time, the change position of the path point can be determined so that the change position is not located in the cutting margin area, taking into consideration the cutting margin area set in advance to protect the surrounding tissue of the bone to be operated on.

[0017] In addition, the step of generating the modified cutting path may further include the step of comparing the area of ​​the cutting surface with the area of ​​the cutting area predicted according to the first modified cutting path to determine whether to further modify the first modified cutting path; and the step of increasing the number of the unit cutting paths constituting the first modified cutting path according to the result of the determination of whether to further modify, thereby generating a second modified cutting path.

[0018] Here, the method may further include a step of determining a movement limit distance that the cutting tool can continuously move in a predetermined direction at one time through information stored in advance regarding the cutting tool of the surgical robot, and the step of generating the second modified cutting path may include a step of determining an additional position at which a new path point is to be added by considering the outer line of the cutting surface and the movement limit distance of the cutting tool; a step of generating a new path point at the additional position; and a step of additionally generating a new unit cutting path to the first modified cutting path using the new path point.

[0019] At this time, the step of determining an additional location where the new path point is to be added may be such that the path point is not added within a range less than a predetermined distance from the outer line of the cross-section.

[0020] In addition, the step of determining an additional location to which the new path point is to be added may determine the additional location as a location where the movement amount of the cutting tool corresponding to the predetermined direction from the existing path point does not exceed the movement limit distance.

[0021] The above object can also be achieved by a cutting path planning device of a surgical robot according to another aspect of the present invention, which plans a cutting path of the surgical robot, comprising: a memory unit for storing implant planning information including a planned implant installation position and posture for a virtual bone model corresponding to a bone to be operated on, and one or more standard cutting paths; and a processor, wherein the processor is configured to generate a cutting plane of the bone model based on the implant planning information, select a standard cutting path corresponding to the cutting plane of the bone model from among the stored one or more standard cutting paths, and modify the selected standard cutting path based on an outline of the cutting plane to generate a modified cutting path.

[0022]

[0023] As described above, according to the present invention, a patient-tailored cutting path that takes into account the bone diversity of each patient can be automatically generated, thereby further improving the surgical effect.

[0024] Additionally, according to the present invention, a patient-specific cutting path can be quickly planned by expanding the cutting path based on a pre-stored standard cutting path.

[0025] In addition, according to the present invention, the surgical process can be simplified and surgical delay can be effectively prevented by creating a cutting path that can minimize the residual bone area remaining after cutting by a surgical robot.

[0026]

[0027] FIG. 1 is a schematic diagram showing the configuration of a joint replacement robotic surgery system including a surgical robot cutting path planning device according to one embodiment of the present invention;

[0028] FIG. 2 is a block diagram showing a detailed configuration of a cutting path planning device according to one embodiment of the present invention;

[0029] FIG. 3 is a flowchart showing a cutting path planning method of a surgical robot according to one embodiment of the present invention;

[0030] FIG. 4a and FIG. 4b are drawings illustrating a standard cutting path according to an embodiment of the present invention;

[0031] Figure 5 is a reference diagram for explaining the concept of the limit distance of movement of a cutting tool;

[0032] Fig. 6 is a flowchart showing the detailed process of the step of generating the first modified cutting path of Fig. 3;

[0033] FIGS. 7 and 8 are drawings each showing an example of modifying a standard cutting path without adding path points, according to an embodiment of the present invention;

[0034] FIG. 9 is a reference diagram for explaining an example of determining a change position of a path point when modifying a standard cutting path in a zigzag shape such as FIG. 8;

[0035] Fig. 10 is a flowchart showing the detailed process of the step of generating the second modified cutting path of Fig. 3;

[0036] FIG. 11 and FIG. 12 are drawings each showing an example of modifying a standard cutting path by adding a new path point according to an embodiment of the present invention; and

[0037] FIG. 13a and FIG. 13b are reference drawings for explaining a method of adding a longitudinal path point according to an embodiment of the present invention.

[0038]

[0039] Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. However, detailed descriptions of well-known functions or components that may obscure the gist of the present invention will be omitted in the following description and the attached drawings. It should also be noted that, where possible, identical components are indicated with the same reference numerals throughout the drawings.

[0040] The surgical robot cutting path planning device according to the present invention plans a cutting path for a bone to be cut by a surgical robot to install an implant during artificial joint replacement surgery. Artificial joint replacement surgeries described herein include total knee replacement, partial knee replacement, and hip replacement. Hereinafter, total knee replacement surgery will be described as an example among artificial joint replacement surgeries.

[0041] FIG. 1 is a schematic diagram showing the configuration of a joint replacement robotic surgery system (1) including a surgical robot cutting path planning device according to one embodiment of the present invention.

[0042] Referring to FIG. 1, the robotic surgical system for endoscopic replacement (1) includes bone markers (BM1, BM2) fixed to surgical target bones (B1, B2), a surgical robot (100), a tracking device (200), and a surgical robot cutting path planning device (300) (hereinafter, “cutting path planning device”).

[0043] The surgical target bones (B1, B2) refer to the bones that will be subjected to robotic surgery. Figure 1 shows the femur (B1) and tibia (B2) as examples. Bone markers (BM1, BM2) that serve as reference points for tracking the positions of the femur (B1) and tibia (B2) during surgery are fixedly installed on the femur (B1) and tibia (B2), respectively.

[0044] The surgical robot (100) is a robot that performs surgery for joint replacement and is composed of a robot base (101) and a robot arm (103). Various cutting tools (105) including burs for performing bone cutting, etc. can be combined at the end effector at the end of the robot arm (103). As the cutting tool (105), various types of tools can be applied, such as a milling cutter that performs cutting through a rotational motion and a sawblade cutter that performs cutting through a translational motion.

[0045] In addition, the surgical robot (100) may be equipped with various sensors capable of sensing status information of the surgical robot (100), such as the load applied to the combined cutting tool and the operating speed of the robot. A robot marker (RM), which serves as a reference for tracking the location of the surgical robot (100) during surgery, is fixed to the base (101) of the surgical robot (100).

[0046] For reference, the bone markers (BM1, BM2) and the robotic marker (RM) can be optical markers of either passive or active types. The optical marker includes multiple bar-shaped members branching in different directions from a central point, and a ball marker can be formed at the end of each bar. This is only one example of the shape of the optical marker, and it goes without saying that the optical marker can be implemented in various other known shapes.

[0047] The tracking device (200) is for tracking the position and posture of bone markers (BM1, BM2) fixed to the surgical target bones (B1, B2) and the robot marker (RM) fixed to the surgical robot (100), and can be implemented as an optical tracking system (OTS). For reference, the optical tracking system is a device that can track the position and posture in a three-dimensional space in real time by tracking the markers using two infrared cameras and converting the distance using triangulation. Since the tracking principle of such an optical tracking system is widely known, a detailed description will be omitted for the sake of simplicity.

[0048] The cutting path planning device (300) plans the cutting path of the surgical robot (100) for the surgical target bone (B1, B2) that requires cutting in order to install an implant in the surgical target bone (B1, B2) during joint replacement surgery. The planning of the cutting path may be performed before the robot surgery or may be performed according to a change in the plan during the surgery. The cutting path includes information on the position to which the surgical robot (100) must move during the process of performing cutting while moving along the cutting path from the starting point where the cutting path begins to the ending point where the cutting path ends, and information on the posture of the surgical robot (100) at the corresponding position. The cutting path may be generated by including the relative position of the surgical robot (100) during the cutting process with respect to the implant coordinate system and information on the posture of the surgical robot (100). For reference, the cutting path is a concept that includes not only the path along which the bone to be operated on is directly cut by the cutting tool (105) of the surgical robot (100), but also the movement path through which the surgical robot (100) approaches the bone to be operated on for cutting.

[0049] The cutting path planning device (300) can be implemented through a computing device including a processor for planning a cutting path, a display for displaying the planned cutting path, and a memory for storing the generated cutting path information. For reference, in FIG. 1, the cutting path planning device (300) is illustrated as being implemented as a separate device physically separated from the surgical robot (100). However, in some cases, the processor and memory of the cutting path planning device (300) may be provided within the surgical robot (100), the display may be installed together with the tracking device (200) and implemented to transmit and receive various types of information through a communication module. In addition, as described above, since the planning of the cutting path can be performed even before the surgery, the cutting path planning device (300) may not necessarily be located in the same space as the surgical robot (100) and the tracking device (200) required for performing the surgery, but may be located in a space far away from them. In this case, the cutting path data planned through the cutting path planning device (300) is transmitted to the surgical robot (100) using various wired and wireless communication methods so that the surgical robot (100) can perform the surgery according to the planned cutting path.

[0050] Fig. 2 is a block diagram showing a detailed configuration of a cutting path planning device (300) according to an embodiment of the present invention. Referring to Fig. 2, the cutting path planning device (300) according to an embodiment of the present invention includes a user interface unit (310), a display unit (320), a memory unit (330), and a processor (340).

[0051] The user interface unit (310) is a module for receiving various inputs from the user during the process of planning the cutting path of the surgical robot (100), and can be implemented with various input devices such as a mouse, keyboard, keypad, button, or pendant.

[0052] The display unit (320) is for displaying various information including images, graphics, text, etc. on the screen, and may be implemented as a liquid crystal display (LCD) panel, a light emitting diode (LED) panel, an organic light emitting diode (OLED) panel, etc. In addition, the user input unit (310) and the display unit (320) may be integrated, such as a touch screen, and implemented as a single device. The display unit (320) displays various GUIs and planning outputs provided in the planning process of the implant position and posture and the planning process of the cutting path of the surgical robot (100), including an implant model, a 2D image and 3D model of the bone to be operated on, and a cutting path of the surgical robot (100).

[0053] The memory unit (330) is implemented with a memory device such as RAM, flash memory, EPROM, etc., and can store at least one computer program code executed by the processor (340). Such computer program code may be loaded into the memory unit (330) from a floppy drive, disk, tape, DVD / CD-ROM drive, memory card, etc. separate from the memory unit (330). In addition, the memory unit (330) stores a CT image or MRI image of the patient taken before surgery, an implant library storing implant attribute information such as implant type / shape / length / size, a standard cutting path generated based on implant volume, information about cutting tools including the type of cutting tool mounted on the robot arm of the surgical robot (100) and cutting characteristics of the cutting tool such as cutting depth, cutting width, and movement limit distance according to a predetermined direction, and other various reference information applied in the process of planning the cutting path of the surgical robot (100).

[0054] The processor (340) executes a program code stored within the device to perform a cutting path planning procedure of the surgical robot (100) for the bone to be operated on based on a standard cutting path that has been generated and stored in advance. That is, the processor (340) plans the cutting path of the surgical robot (100) by modifying the standard cutting path stored in advance in response to the bone to be operated on, rather than generating the cutting path from scratch.

[0055] Hereinafter, a surgical robot cutting path planning method performed by a cutting path planning device (300) will be described with reference to FIGS. 3 to 13.

[0056] Figure 3 is a flowchart illustrating a cutting path planning method of a surgical robot according to one embodiment of the present invention.

[0057] Referring to FIG. 3, it is assumed that standard cutting path data and information on cutting tools are stored in the cutting path planning device (300) (S100). The standard cutting path is a cutting path generated based on the implant rather than the bone shape of a specific patient so that it can be applied to the surgical target bone of various patients. It is generated by considering the characteristics of each implant including the implant type, shape, and size, and the cutting surface that requires cutting. The standard cutting path is generally generated to be located within the volume of the implant, except for the portion corresponding to the initial entry path for the surgical robot (100) to approach the surgical target bone for cutting among the entire path. This is to limit the cutting area that is actually cut to within the implant volume in order to protect soft tissues such as ligaments, blood vessels, muscles, and skin.

[0058] FIGS. 4A and 4B are drawings illustrating a standard cutting path according to an embodiment of the present invention.

[0059] Referring to FIGS. 4a and 4b, the standard cutting path (410, 420) is composed of a plurality of unit cutting paths (SL) and includes a plurality of path points (P) corresponding to the start point and end point of each unit cutting path (SL).

[0060] In addition, according to FIGS. 4A and 4B, examples of standard cutting paths (410, 420) composed of two partial cutting paths are shown for one cutting surface of the bone to be operated on, respectively. That is, FIG. 4A illustrates a standard cutting path (410) composed of a first partial cutting path (410a) and a second partial cutting path (420a), and FIG. 4B illustrates a standard cutting path (420) composed of a first partial cutting path (410b) and a second partial cutting path (420b). In this way, the standard cutting path may be generated as one path for one cutting surface of the bone to be operated on, but may also include two or more partial cutting paths that are separated from each other for one cutting surface. In addition, the path point (P) is a point located on the cutting path, and is the starting point (P) of the cutting path or each partial cutting path. S ) and the end point (P E ), it can be seen that each path point (P) corresponds to a turning point where the direction of the cutting tool (105) is changed as a point where two unit cutting paths (SL) are connected to each other.

[0061] FIG. 4a shows an example of a standard cutting path (410) composed of a combination of transverse, longitudinal, and diagonal unit cutting paths (SL) that are perpendicular to each other. Specifically, it shows a standard cutting path composed of a combination of a first unit cutting path (SL1) in which a cutting tool cuts while moving transversely on the unit cutting path (SL), a second unit cutting path (SL2) in which a cutting tool cuts while moving longitudinally, and a third unit cutting path (SL3) in which a cutting tool (105) cuts while moving diagonally including both transverse and longitudinal components. Meanwhile, FIG. 4b shows a zigzag-shaped standard cutting path composed of diagonal unit cutting paths (SL) that include both transverse and longitudinal components. Here, it should be noted that the directions such as transverse, longitudinal, and diagonal directions do not mean the direction of the unit cutting path itself with respect to the implant coordinate system, but the direction in which the cutting tool moves on the unit cutting path, which is defined with respect to the cutting tool.

[0062] Although two types of standard cutting paths are exemplified through FIGS. 4A and 4B, the standard cutting path is not limited thereto, and the standard cutting path can be prepared in various shapes depending on the type of bone to be operated on, such as tibia or femur, the location of the cutting surface in the bone, such as anterior or posterior, and the type or size of the implant to be installed. For example, in FIG. 4B, a zigzag-shaped standard cutting path (420) consisting only of a combination of diagonal unit cutting paths is exemplified, but in addition, Of course, a zigzag-shaped standard cutting path is also possible, which is composed of two parallel unit cutting paths and a unit cutting path that diagonally connects the two unit cutting paths above. In this way, the standard cutting path can be composed of various forms, such as a first unit cutting path in which the cutting tool of the surgical robot moves laterally on the path, a second unit cutting path in which the cutting tool moves longitudinally, or a third unit cutting path in which the cutting tool moves diagonally including both transverse and longitudinal components.

[0063] One or more standard cutting paths generated can be stored in a library format, classified into categories based on the location of the implant and / or cutting surface.

[0064] Meanwhile, information about the cutting tool may include cutting characteristics such as the type of cutting tool, diameter and size of the cutting tool, cutting depth, cutting width, etc., and in particular, includes a moving limit distance that the cutting tool can move continuously in a specific direction at one time.

[0065] Figure 5 is a reference diagram for explaining the concept of the limit distance of movement of a cutting tool.

[0066] Cutting tools have a defined travel limit, or the distance they can move in a specific direction (or directional component) at a time, depending on their type. Even for the same type of cutting tool, the specific travel limit value may vary depending on factors such as the tool's diameter or size.

[0067] Referring to FIG. 5, (a) of FIG. 5 shows the movement characteristics of a milling cutter, and (b) shows the movement characteristics of a cutting tool (105) of the saw blade cutter type. First, referring to (a), when performing cutting, there is a limit to the distance that the milling cutter (105a) can continuously move in the longitudinal direction (longitudinal component) (D2) at one time based on the milling cutter (105a). Accordingly, even when the milling cutter (105a) cuts while moving in a diagonal direction including both a transverse component (D1) and a longitudinal component (D2), it is bound by the movement limit distance condition according to the longitudinal direction (D2).

[0068] On the other hand, the saw blade cutter (105b) has a limit to the distance it can move continuously in the transverse direction (D1). Accordingly, even when cutting while moving in a diagonal direction, the saw blade cutter (105b) is bound by the movement limit condition in the transverse direction (D1).

[0069] As such, since there is a movement limit distance for a specific direction (directional component) depending on the type of cutting tool, as described below, it is important to plan the cutting tool movement distance in a specific direction when planning a cutting path, that is, the cutting tool movement distance on a unit cutting path corresponding to a specific direction, so as not to exceed the movement limit distance.

[0070] Next, planned implant planning information regarding the implant to be installed in the surgical target bone is confirmed (S200). The implant planning information can be generated based on a virtual 3D bone model corresponding to the surgical target bone of a specific patient, and includes information on the installation location and installation posture of the implant to be installed in the bone model. Here, the installation posture refers to the angle or direction in which the implant is installed. The surgical target bone model is a model that is 3D reconstructed of the surgical target bone based on medical images of the patient acquired before surgery, such as CT images and MRI images.

[0071] The determination of the installation position and posture of the implant can be made based on user input through the user interface unit (310). When the user selects an implant to be installed in the surgical target bone from the implant library, the processor (340) creates a virtual model of the selected implant and displays it superimposed on a 3D bone model, and an appropriate installation position and posture, such as an installation angle, of the implant can be determined based on user input for moving the implant virtual model on the 3D bone model through the user interface unit (310).

[0072] Meanwhile, as described above, the determination of the installation position and posture of the implant may not be entirely based on user input, but may be automatically performed based on preset implant installation criteria. For example, the processor (340) may be implemented to identify the position of a predetermined landmark in a 3D bone model and the shape, size, etc. of the landmark, and determine the type of implant, the appropriate installation position, and posture of the implant based on the implant installation criteria information in response to the identified result. Implant planning information determined by user input or the processor (340) may be stored and loaded.

[0073] As described above, when implant planning information regarding the implant installation position and posture is confirmed, a cross-section of a bone model is generated based on the implant planning information (S300). Here, the cross-section refers to a cross-section generated by virtually cutting a surface that needs to be cut for joint surgery in a bone model corresponding to a state before cutting. Although no actual cutting has been performed, the processor (340) predicts the state after cutting based on the 3D model of the surgical target bone in the state before cutting and generates a cross-section in the bone model. The processor (340) can generate a cross-section by predicting the state in which the corresponding cut surface has been cut based on the characteristics of the implant to be installed in the surgical target bone, such as the installation position and posture of the implant, the shape and size of the implant, and the cutting characteristics of the cutting tool that will perform the cutting, for example, the depth of one cut, the cutting width, etc., according to the implant planning information.

[0074] Once the cross-section creation is complete, the outline of the created cross-section is detected (S400). The outline can be detected based on various rule-based detection algorithms that recognize line information based on the shape, color, etc. of the object appearing in the image as the outermost border of the cross-section, or a deep learning-based algorithm trained to detect the outline in the cross-section through a convolutional neural network (CNN), R-CNN, YOLO, etc.

[0075] Next, the processor (340) selects a standard cutting path corresponding to the cross-section of the bone model from among one or more standard cutting paths pre-stored in the cutting path planning device (300) (S500). The selection of the standard cutting path may be made by considering the implant type and size, as well as the location and shape of the cross-section, according to the implant planning information.

[0076] For example, selection criteria for selecting a standard cutting path may be set in advance based on the location of each cutting surface, and / or the type or size of the implant, and the processor (340) may select a standard cutting path based on the set criteria, or may select a standard cutting path input through the user input unit (310). Alternatively, a standard cutting path frequently used in previous robotic surgeries may be selected based on the surgical information history.

[0077] In this way, when a standard cutting path is selected, a procedure for generating a modified cutting path by modifying the selected standard cutting path is performed (S600). As described above, since the standard cutting path is typically generated to be located within the implant volume, the modification of the standard cutting path is performed by extending the standard cutting path toward the outer line of the cutting surface. The extension of the standard cutting path is performed to increase the area to be cut, and as described below, this can be done by changing the length of a unit cutting path without adding path points that constitute the standard cutting path, or by adding a new unit cutting path by adding path points.

[0078] Hereinafter, in order to generate a modified cutting path based on a standard cutting path, the processor (340) first generates a first modified cutting path by changing the length of one or more unit cutting paths constituting the standard cutting path (S610). The first modified cutting path refers to a cutting path generated by extending the standard cutting path by changing the length of one or more unit cutting paths by changing the positions of existing path points without increasing the number of existing path points constituting the standard cutting path.

[0079] For reference, since the modification of the standard cutting path is basically performed to expand the area to be cut in order to reduce the residual bone area remaining after cutting by the surgical robot (100), modification may not be performed on a movement path among the standard cutting paths where cutting is not actually performed, for example, a part corresponding to the entry path for the surgical robot (100) to approach the bone to be surgically cut.

[0080] FIG. 6 is a flowchart illustrating a detailed process of step S610 of generating a first modified cutting path of FIG. 3, and FIGS. 7 and 8 are reference diagrams for explaining a process of generating a first modified cutting path according to an embodiment of the present invention. Hereinafter, with reference to FIGS. 6 to 8, a process of generating a first modified cutting path based on a standard cutting path will be described.

[0081] Referring to FIG. 6, the processor (340) recognizes the intersections of the extension lines of each unit cutting path constituting the standard cutting path and the outer lines of the cutting plane (S611).

[0082] Next, based on the above intersection points, the position to be changed of one or more existing path points of the standard cutting path is determined (S613). At this time, the position to be changed is determined based on the movement direction of the cutting tool on the corresponding unit cutting path where the existing path point before change is located, and the movement limit distance information of the cutting tool.

[0083] The processor (340) generates a first modified cutting path by modifying the existing unit cutting path by applying the changed path point to the changed position determined in step S613 (S615).

[0084] FIG. 7 and FIG. 8 are drawings each showing an example of modifying a standard cutting path without adding a path point. FIG. 7 shows an example of modifying a standard cutting path (410) configured around the transverse and longitudinal unit cutting paths shown in FIG. 4a, and FIG. 8 shows an example of modifying a zigzag-shaped standard cutting path (420) shown in FIG. 4b. For reference, in FIG. 7 and FIG. 8, it is assumed that the cutting tool is constrained to move within a predetermined limit distance range with respect to longitudinal movement.

[0085] First, referring to FIG. 7, the positions of the existing path points (710 to 720, 730 to 735) are changed to positions (710' to 720', 730' to 735') corresponding to the intersections of the extension of the unit cutting path (SL) and the outer line (ML) of the cutting plane, respectively, so that the length of the unit cutting path (SL) is extended, and it can be confirmed that the standard cutting path is extended overall toward the outer line (ML) of the cutting plane. At this time, the extension of the existing unit cutting path in which the cutting tool moves laterally on the unit cutting path can be performed in the direction in which the cutting tool moves from the inside of the surgical target bone to the outside of the bone, that is, toward the outer line (ML) of the cutting plane.

[0086] For reference, for the lower path of the first partial cutting path (410a) of FIG. 7, that is, the path portion including path points 710 to 718, the X-axis direction corresponds to the longitudinal movement of the cutting tool and the Y-axis direction corresponds to the lateral movement of the cutting tool, according to the implant coordinate system, and for the upper path of the first partial cutting path (410a), that is, the upper path including path points 719 and 720, the X-axis direction corresponds to the lateral movement of the cutting tool and the Y-axis direction corresponds to the longitudinal movement of the cutting tool. On the other hand, for the second partial cutting path (410b), the X-axis direction corresponds to the lateral movement of the cutting tool and the Y-axis direction corresponds to the longitudinal movement of the cutting tool.

[0087] At this time, for a unit cutting path (SL) corresponding to a transverse movement in which the movement of the cutting tool is not restricted on the unit cutting path (SL), the length can be extended to the outer line (ML) of the cutting surface. However, for a unit cutting path (SL) in which the cutting tool moves longitudinally on the unit cutting path (SL), the extension is limited because the preset longitudinal movement limit distance value of the cutting tool cannot be exceeded. Here, the longitudinal movement of the cutting tool is understood as a concept including a diagonal movement including a longitudinal component movement. Referring to FIG. 7, when a cutting tool moves longitudinally or includes a longitudinal movement component on a unit cutting path (SL), such as a unit cutting path (SL) connecting path points 711 and 712, a unit cutting path (SL) connecting 713 and 714, a unit cutting path (SL) connecting 715 and 716, or a unit cutting path (SL) connecting 717 and 718, the movement amount of the cutting tool is limited to a movement limit distance, so that the change in position of the cutting point is limited so that the movement amount of the longitudinal component is within a movement limit distance range.

[0088] Referring to FIG. 8, the shape of the standard cutting path (420) is different from that of FIG. 7 in that it is in a zigzag shape, but the basic expansion concept is the same as that seen in FIG. 7.

[0089] Since each unit cutting path (SL) constituting the standard cutting path (420) according to Fig. 8 is diagonal, each unit cutting path (SL) basically includes both the transverse component movement and the longitudinal component movement of the cutting tool. Accordingly, when the length of the unit cutting path (SL) in the diagonal direction is extended, the position of the cutting point is changed so that the longitudinal component movement amount exists within the movement limit range of the cutting tool.

[0090] That is, referring to FIG. 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, 830 to 836) are changed to positions (810' to 820', 830' to 836') corresponding to the intersection of the extension line of the unit cutting path (SL) of the cutting surface and the outer line (ML) of the cutting surface, and through this, the length of the unit cutting path (SL) is extended, so that it can be confirmed that the standard cutting path is extended overall toward the outer line (ML) of the cutting surface.

[0091] Fig. 9 is a reference diagram for explaining an example of determining the change position of a path point when modifying a standard cutting path in a zigzag shape such as Fig. 8. The path illustrated in Fig. 9 is a portion of the cutting path, and in the upper portion of the cutting path, the Y-axis direction corresponds to the longitudinal movement of the cutting tool according to the implant coordinate system. In addition, it is assumed that the cutting tool is constrained to move within a predetermined limit distance range with respect to the longitudinal movement.

[0092] Referring to FIG. 9, a virtual straight line (907) is created between the midpoint (905) of two first and second path points (901, 902) in a longitudinal movement relationship of the cutting tool and an existing third path point (903) corresponding to the intersection of two existing unit cutting paths (pSL), and the intersection of the above straight line (907) and the outer line (ML) of the cutting plane or a point located a predetermined distance inside the bone from the intersection for soft tissue protection can be determined as the new change position (903') of the existing cutting point (903). Through this, the standard cutting path can be extended while satisfying the movement limit distance condition of the cutting tool for longitudinal movement.

[0093] For reference, as described above, the intersection point on the extension line of each unit cutting path and the outer line of the cutting plane can be directly determined as the change position of the path point, but the change position of the path point can also be determined as a position a predetermined distance inside the bone from the intersection point, taking into account a preset cutting margin area.

[0094] Here, the cutting margin area is an area set to be excluded from cutting for the protection of soft tissue, and can be set as an area that extends a predetermined distance into the bone to be operated on from the outer line (ML) of the cutting plane. The size of the distance extending into the bone can be a preset value, and can also be set to a different value depending on the type of cutting tool. Accordingly, the processor (340) can extend the standard cutting path toward the outer line (ML) of the cutting plane, but determine the changed location so that the changed location of the path point is not located in the preset cutting margin area.

[0095] As described above, when the first modification process of modifying the standard cutting path by changing the length of the unit cutting path without increasing the number of path points is completed, the processor (340) compares the area of ​​the cutting area predicted according to the first modified cutting path generated through the above process with the area of ​​the cross-section of the bone model to determine whether additional modification is necessary (S620). For reference, when predicting the cutting area according to the first modified cutting path, the cutting tool passes through the cutting path but does not actually perform cutting, or the path along which the cutting tool simply passes repeatedly to move to the next cutting position after cutting is not cumulatively calculated when predicting the cutting area.

[0096] If the area of ​​the cutting area predicted according to the first modified cutting path is smaller than the area of ​​the cutting surface, or if the difference is greater than a preset value, the processor (340) can generate a second modified cutting path by modifying the first modified cutting path through a second modification that newly adds path points (S630). That is, the second modification modifies the standard cutting path by increasing the number of unit cutting paths as a result of adding new path points.

[0097] FIG. 10 is a flowchart illustrating a detailed process of step S630 of generating a second modified cutting path in FIG. 3, and FIGS. 11 to 13 are reference diagrams for explaining a process of generating a second modified cutting path according to an embodiment of the present invention. Hereinafter, the process of generating a second modified cutting path will be described with reference to FIGS. 10 to 13.

[0098] First, referring to FIG. 10, the processor (340) determines additional locations where new path points will be added by considering the outline of the cross-section of the bone model and the movement limit distance of the cutting tool along a predetermined direction (S631). At this time, the processor (340) may prevent new path points from being created within a range less than a predetermined distance from the outline of the cross-section by considering the aforementioned cutting margin area.

[0099] Next, a new path point is created at the determined location, and a new unit cutting path is added to the first modified cutting path using the created new path point (S633, S635).

[0100] FIG. 11 and FIG. 12 are drawings showing examples of modifying a standard cutting path by adding a new path point, respectively. FIG. 11 shows an example of modifying a standard cutting path centered on transverse and longitudinal unit cutting paths as seen in FIG. 7, and FIG. 12 shows an example of modifying a zigzag-shaped standard cutting path as seen in FIG. 8. In FIG. 11 and FIG. 12, it is assumed that the cutting tool is constrained to move within a predetermined limit distance range with respect to longitudinal movement. For reference, newly added new path points are shown as '*' to distinguish them from existing path points.

[0101] In FIGS. 11 and 12, (a) shows a first modified cutting path in which the first modification of changing the length of the unit cutting path with respect to the standard cutting path has been completed, and (b) shows a state in which a second modified cutting path is created by newly adding a unit cutting path based on the added new path point.

[0102] Even when adding a new path point, just like changing the location of a path point, a new path point is added at a location where the distance traveled in a predetermined direction (directional component) of the cutting tool from the immediately preceding existing path point does not exceed a preset travel limit distance.

[0103] According to the embodiments of FIGS. 11 and 12, when adding a new path point, the processor (340) may first add a longitudinal path point to be located on a longitudinal movement line where the movement of the cutting tool is constrained by a movement limit distance, and then add a transverse path point to be located on a transverse movement line of the cutting tool based on the added longitudinal path point. Meanwhile, it goes without saying that both the longitudinal path point and the transverse path point are created at a location that does not exceed the boundary of the outer line of the cutting surface.

[0104] Regarding this, first, referring to Fig. 11, in a cutting path such as (a), further expansion is not possible by simply changing the length of the unit cutting path (SL), so the cutting path is expanded by adding path points.

[0105] When adding new path points (1101 to 1108), it is important to ensure that the cutting tool movement from the existing path points does not exceed a preset movement limit distance for the new path points located on the longitudinal movement line where the movement of the cutting tool is limited. As an example of generating new path points, the processor (340) may first add 1101, 1103, 1104, and 1108 corresponding to new path points on the longitudinal movement line so that the cutting tool movement from the immediately preceding existing path point satisfies the preset movement limit distance value, and then generate virtual lines starting from 1101, 1103, 1104, and 1108 respectively and heading toward the outer line (ML) of the cutting surface, and generate new path points 1102, 1105, 1106, and 1107 based on the intersections of the above virtual lines and the outer line (ML) of the cutting surface. New unit cutting paths (nSL) are created by connecting new path points (1101 to 1108).

[0106] For reference, 1102 and 1105 are new path points included in a new unit cut (nSL) in which the cutting tool proceeds in a diagonal direction including both lateral and longitudinal movement components from the immediately previous path point, and are restricted by a preset movement limit distance for the longitudinal component of the cutting tool. However, since the longitudinal movement limit distance value was already considered when adding path points 1103 and 1108, it can be seen that 1102 and 1105, which exist on the same lateral movement path of the cutting tool as 1103 and 1108 above, also satisfy the longitudinal movement limit distance value of the cutting tool.

[0107] FIG. 13a and FIG. 13b are reference drawings for explaining a method of adding a longitudinal path point according to an embodiment of the present invention.

[0108] First, referring to FIG. 13a, a virtual straight line (1301) is created by extending the previous longitudinal unit cutting path (pSL) among the existing unit cutting paths, and one or more new longitudinal path points (1302, 1303) located on the longitudinal movement line at positions spaced apart from each other so as not to exceed the movement limit distance value of the cutting tool on the upper straight line (1301) can be added.

[0109] Alternatively, as described above, a vector direction corresponding to the longitudinal direction in the implant coordinate system can be used without generating a virtual straight line (1301). That is, referring to FIG. 13b, a vector corresponding to the longitudinal direction in the implant coordinate system can be used from the immediately previous path point (1307) on the longitudinal movement line among the existing path points ( ) can be added at a location spaced apart by a distance that does not exceed the movement limit distance value in the direction of the longitudinal path point (1309).

[0110] As above, there may be several ways to add longitudinal path points, but all of these methods are the same in that they create transverse path points that exist on the transverse movement line based on the intersection of the virtual cutting tool transverse movement line starting from the newly added longitudinal path point and the outer line of the cutting surface.

[0111] Meanwhile, adding a new path point in a zigzag-shaped cutting path can also be performed in the same manner as described with reference to FIG. 11.

[0112] That is, according to the zigzag-shaped cutting path as shown in Fig. 12, since each unit cutting path has an oblique direction that includes both the transverse movement component and the longitudinal movement component of the cutting tool, it is necessary to create a new path point so that the longitudinal movement component does not exceed the movement limit distance value of the cutting tool.

[0113] Accordingly, when adding a new path point in a zigzag-shaped cutting path such as FIG. 12, the position of the new path point is limited to the size of the longitudinal movement component from the immediately previous path point to the new path point by the preset cutting tool movement limit distance value, and the size of the transverse movement component is not particularly limited as long as it does not exceed the boundary of the outer line of the cutting surface or the boundary of the preset cutting margin area (if applicable).

[0114] Meanwhile, when creating a new unit cutting path by connecting a new path point adjacent to an existing path point, if the movement limit distance of the cutting tool is exceeded, a new path point may be additionally created in the middle. For example, if a new unit cutting path (nSL) is created by connecting the existing path point 1208 and the new path point 1210 among the cutting paths of FIG. 12, assuming that the movement distance corresponding to the longitudinal component of the cutting tool exceeds the movement limit distance of the cutting tool, the processor (340) may modify the cutting path to pass through 1209 by adding a new path point in the middle, such as 1209, rather than creating a new unit cutting path (nSL) by connecting 1208 and 1210.

[0115] Among the steps of FIG. 3 described above, steps S300 to S600 are shown to be performed for one cut surface. If there are multiple cut surfaces, steps S300 to S600 are repeatedly performed for each cut surface.

[0116] The cutting path planning device (300) can store the final cutting path after modification and display it through the display unit (320), thereby allowing the user to check the final cutting path.

[0117] As described above, according to the present invention, by modifying the standard cutting path and planning a cutting path customized to the cut surface of the bone to be operated on, the surgical plan can be established more efficiently than planning the cutting path from the beginning, and the residual bone area remaining after cutting by the surgical robot can be minimized, thereby simplifying the surgical process and effectively preventing surgical delays.

[0118] The present invention can also be implemented as various computer-readable recording media, such as a magnetic storage medium, an optical reading medium, or a digital storage medium, in which a computer program for performing a surgical robot cutting path planning method according to the present invention is stored when executed on a computer.

[0119] While several embodiments of the present invention have been described so far, those skilled in the art will appreciate that modifications or substitutions of certain embodiments may be made without departing from the technical spirit of the present invention. Therefore, the scope of protection of the present invention should be deemed to encompass the inventions described in the claims and their equivalents.

Claims

1. In a cutting path planning method of a surgical robot in which each step is performed by a computing device, A step of confirming implant planning information including the planned implant installation location and posture for a virtual bone model corresponding to the bone to be operated on; A step of creating a cross-section of the bone model based on the implant planning information; A step of selecting a standard cutting path corresponding to the cutting plane of the bone model from among one or more standard cutting paths pre-stored in the computing device; and A cutting path planning method for a surgical robot, characterized in that it includes a step of generating a modified cutting path by modifying the selected standard cutting path based on the outline of the cutting plane.

2. In paragraph 1, The step of generating the above modified cutting path is: A cutting path planning method for a surgical robot, characterized in that the standard cutting path is extended toward the outer line of the cutting surface.

3. In paragraph 1, The above standard cutting path is, A cutting path planning method for a surgical robot, characterized in that it comprises a plurality of unit cutting paths and includes a plurality of path points corresponding to the start point and end point of each unit cutting path.

4. In paragraph 3, The step of generating the above modified cutting path is: A method for planning a cutting path of a surgical robot, characterized in that it comprises a step of generating a first modified cutting path by changing the length of one or more of the above unit cutting paths.

5. In paragraph 4, The step of generating the first modified cutting path is: A step of recognizing the intersection of the extension line of the above unit cutting path and the outer line of the above cutting surface; A step of determining a change location of the path point based on the intersection point; and A cutting path planning method for a surgical robot, characterized in that it includes a step of modifying the unit cutting path by applying the path point whose position has been changed to the changed position.

6. In paragraph 5, Further comprising a step of determining the movement limit distance that the cutting tool can continuously move in a predetermined direction at one time through information stored in advance regarding the cutting tool of the surgical robot. A method for planning a cutting path of a surgical robot, characterized in that the step of determining a change position of the above path point determines the change position by considering the movement direction of the cutting tool on the unit cutting path and the movement limit distance of the cutting tool.

7. In paragraph 5, A cutting path planning method for a surgical robot, characterized in that the change position of the above path point is determined so that the change position is not located in a cutting margin area set in advance to protect the surrounding tissue of the bone to be operated on.

8. In paragraph 4, The step of generating the above modified cutting path is: A step of comparing the area of ​​the cut surface and the area of ​​the cutting area predicted according to the first modified cutting path to determine whether to make additional modifications to the first modified cutting path; and A cutting path planning method for a surgical robot, characterized in that it further includes a step of generating a second modified cutting path by increasing the number of unit cutting paths constituting the first modified cutting path according to the result of the decision on whether to perform the additional modification.

9. In paragraph 8, Further comprising a step of determining the movement limit distance that the cutting tool can continuously move in a predetermined direction at one time through information stored in advance regarding the cutting tool of the surgical robot. The step of generating the second modified cutting path is as follows: A step of determining an additional location where a new path point is to be added by considering the outer line of the above-mentioned cutting plane and the movement limit distance of the above-mentioned cutting tool; a step of creating a new route point at the above additional location; and A cutting path planning method for a surgical robot, characterized in that it includes a step of additionally generating a new unit cutting path to the first modified cutting path using the new path point.

10. In paragraph 9, The step of determining additional locations where the above new route points will be added is: A cutting path planning method for a surgical robot, characterized in that the path point is not added within a range less than a predetermined distance from the outer line of the cutting plane.

11. In paragraph 9, The step of determining additional locations where the above new route points will be added is: A cutting path planning method for a surgical robot, characterized in that the additional position is determined as a position where the movement amount of the cutting tool corresponding to the predetermined direction from an existing path point does not exceed the movement limit distance.

12. In a cutting path planning device of a surgical robot that plans the cutting path of the surgical robot, A memory unit storing implant planning information including a planned implant installation location and posture for a virtual bone model corresponding to a surgical target bone and one or more standard cutting paths; and Contains a processor, The above processor, Generating a cross-section of the bone model based on the above implant planning information, Select a standard cutting path corresponding to the cross-section of the bone model from among the one or more standard cutting paths saved, A cutting path planning device of a surgical robot configured to generate a modified cutting path by modifying the selected standard cutting path based on the outline of the above-mentioned cutting plane.

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