Orthopedic surgical robot, its bone saw saw surface calibration method and storage medium

Abstract

The present invention relates to an orthopedic surgical robot, a method for calibrating the saw surface of a bone saw thereof, and a storage medium. Among them, the method includes the following steps: S1: Provide a tracker and a tracking bracket, and the tracker cooperates with the tracking bracket to obtain the stretching length x of the passive two-link; S2: Collect data, including the rotation angle θ of the end of the multi-axis robotic arm, the stretching length x of the passive two-link, and the distance d of the bone saw surface from the original position; S3: Process the collected data to fit and obtain the relationship function d(x,θ); S4: During the operation, calculate the distance d of the bone saw surface from the original position according to the relationship function d(x,θ) through the real-time obtained θ and x, so as to realize the calibration of the bone saw surface. By using the method of the present invention, it is possible to correct in real time the error of the bone saw surface caused by the displacement deviation after the stretching of the passive two-link during the operation, reduce the occurrence of surgical accidents, and improve the surgical success rate.

Description

Technical Field

[0001] The present invention relates to the field of orthopedic surgical robots, and particularly to an orthopedic surgical robot, a method for calibrating a bone saw cutting surface thereof, and a storage medium. Background Art

[0002] Total Knee Replacement (TKR) is one of the most effective surgeries for solving severe knee lesions that affect the patient's activity function, and can effectively improve the patient's quality of life. However, the current traditional artificial knee replacement surgery highly depends on the experience of clinicians, and the failure rate due to prosthesis loosening, dislocation, fracture, and infection noise reaches 5% - 8%. Compared with the traditional artificial knee replacement surgery, the knee replacement surgery navigation system combines computer image processing with precise robot planning, conducts intelligent evaluation of force and motion analysis, and assists clinicians to complete knee replacement surgery, which can reduce surgical trauma, reduce surgical time, and improve the surgical success rate and quality.

[0003] The total knee replacement surgery navigation and positioning system can achieve bone saw positioning and operation by adopting a six-axis collaborative robotic arm in parallel with a passive two-link mechanism. The free-moving passive two-link is connected to the end of the robotic arm. When the passive two-link is folded, the robotic arm automatically places the plane where the bone saw is located onto the pre-operative planned osteotomy plane. The user can stretch the two-link to complete the movement of the bone saw and complete the osteotomy operation. However, due to the weight of the bone saw installed at the end of the passive two-link, when the passive two-link is stretched from the folded position to the straightened state, the passive two-link will have a slight downward displacement in the horizontal direction due to gravity, thereby causing the cutting surface of the bone saw to deviate, resulting in osteotomy errors and affecting the surgical accuracy. Therefore, it is of great significance to study a reliable method for calibrating the cutting surface of the bone saw of an orthopedic surgical robot. Summary of the Invention

[0004] The purpose of the present invention is to provide a reliable method for calibrating the cutting surface of the bone saw of an orthopedic surgical robot, an orthopedic surgical robot, and a storage medium.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] According to one aspect of the present invention, there is provided a method for calibrating a cutting surface of a bone saw of an orthopedic surgical robot, the orthopedic surgical robot including a multi-axis robotic arm, a passive two-link, and a bone saw, the first end of the passive two-link being fixed to the end of the multi-axis robotic arm, and the bone saw being fixedly installed at the second end of the passive two-link, wherein the method may include the following steps:

[0007] S1: Provide a tracker and a tracking bracket. The tracking bracket is fixedly installed at the second end of the bone saw or the passive two-link. The tracker cooperates with the tracking bracket to obtain the stretching length x of the passive two-link.

[0008] S2: Collect data, including the rotation angle θ of the end of the multi-axis robotic arm, the stretching length x of the passive two-link, and the distance d that the bone saw surface deviates from the original position.

[0009] S3: Process the collected data, and fit to obtain the relationship function d(x, θ) between the distance that the bone saw surface deviates from the original position, the rotation angle of the end of the multi-axis robotic arm, and the stretching length of the passive two-link.

[0010] S4: During the operation, calculate the distance that the bone saw surface deviates from the original position according to the relationship function d(x, θ) based on the rotation angle of the end of the multi-axis robotic arm and the stretching length of the passive two-link obtained in real time, so as to realize the calibration of the bone saw surface.

[0011] In a preferred embodiment, S3 includes:

[0012] S31: When the rotation angle θ of the end of the multi-axis robotic arm is 0, fit the relationship function d(x) between the distance that the bone saw surface deviates from the original position and the stretching length of the passive two-link, where d(x)=ax2 + bx + c, and a, b, c are constants.

[0013] S32: For different rotation angles θ of the end of the multi-axis robotic arm, fit the relationship function d(x, θ), where d(x, θ)=m + n×cosθ×d(x), and m, n are constants.

[0014] In a preferred embodiment, both S31 and S32 are implemented by least squares fitting.

[0015] In a preferred embodiment, the specific process of S31 is to construct the function d(x)=ax 2 + bx + c; collect the data d(x i ) of the distance d that the bone saw surface deviates from the original position through a laser rangefinder, i = 1, 2,..., N, and collect the data x i of the stretching length x of the passive two-link through the tracker, i = 1, 2,..., N, where N represents the total number of collected data and N>20; solve to obtain the coefficients a, b, and c.

[0016] In a preferred embodiment, the specific process of S32 is to construct the function d(x, θ) = m + n×cosθ×d(x). The data d(x, θ j ) of the distance d that the saw surface of the bone saw deviates from the original position is collected by a laser rangefinder, where j = 1, 2,..., M. The x j is collected by the tracker, where j = 1, 2,..., M, and d(x j ) is calculated according to the relational function of S31, where j = 1, 2,..., M. Here, M represents the total number of collected data, and M > 20. The coefficients m and n are obtained by the least squares method .

[0017] According to another aspect of the present invention, an orthopedic surgical robot is further provided. The orthopedic surgical robot includes a workstation, a multi-axis robotic arm, a passive two-link, a bone saw, a tracker, and a tracking bracket. The first end of the passive two-link is fixed to the end of the multi-axis robotic arm, and the bone saw is fixedly installed at the second end of the passive two-link. The tracking bracket is fixedly installed on the bone saw or the second end of the passive two-link. The tracker cooperates with the tracking bracket to obtain the stretching length of the passive two-link. The workstation is electrically connected to the multi-axis robotic arm, the bone saw, and the tracker and includes a processor and a memory. The memory stores a computer program, and when the processor executes the computer program, the above-mentioned method is implemented.

[0018] In a preferred embodiment, the multi-axis robotic arm is a six-axis robotic arm.

[0019] In a preferred embodiment, the tracker is an optical tracker.

[0020] In a preferred embodiment, the orthopedic surgical robot is used for total knee replacement surgery.

[0021] According to still another aspect of the present invention, a computer-readable storage medium is further provided, on which a computer program executable by a processor is stored. When the processor executes the computer program, the steps of the above-mentioned method are implemented.

[0022] By adopting the above technical solutions, the present invention has the beneficial effect that by stretching the passive two-link at different positions and recording the position of the saw surface of the bone saw, the error of the saw surface of the bone saw at different positions of the passive two-link is calculated, and the error of the saw surface of the bone saw caused by the displacement deviation after stretching the passive two-link can be corrected in real time during the operation, reducing the occurrence of surgical accidents and improving the surgical success rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic diagram of the system architecture of the orthopedic surgical robot of the present invention;

[0024] Figure 2 is a flowchart of the method for verifying the saw surface of the bone saw of the orthopedic surgical robot of the present invention;

[0025] Figure 3 is a schematic diagram of the displacement deviation of the passive two-link of the orthopedic surgical robot of the present invention. Detailed Embodiments

[0026] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings so as to more clearly understand the purpose, features and advantages of the present invention. It should be understood that the embodiments shown in the drawings are not limitations on the scope of the present invention, but only to illustrate the essential spirit of the technical solution of the present invention.

[0027] In the following description, for the purpose of illustrating various disclosed embodiments, certain specific details are set forth to provide a thorough understanding of the various disclosed embodiments. However, those skilled in the relevant art will recognize that the embodiments can be practiced without one or more of these specific details. In other instances, well-known devices, structures, and techniques associated with the present application may not be shown or described in detail so as not to unnecessarily obscure the description of the embodiments.

[0028] Unless the context requires otherwise, throughout the specification and claims, the words "comprise" and its variations, such as "comprising" and "having", should be understood in an open, inclusive sense, i.e., interpreted as "including, but not limited to".

[0029] References to "an embodiment" or "one embodiment" in the specification throughout represent that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of "in an embodiment" or "in one embodiment" in various places throughout the specification are not necessarily all referring to the same embodiment. Additionally, the particular features, structures, or characteristics may be combined in any manner in one or more embodiments.

[0030] As used in this specification and the appended claims, the singular forms "a" and "the" include plural referents unless the context clearly dictates otherwise. It should be noted that the term "or" is generally used in its inclusive sense of "and / or" unless the context clearly dictates otherwise.

[0031] In the following description, in order to clearly show the structure and working mode of the present invention, many directional terms will be used for description. However, the terms "front", "rear", "left", "right", "outer", "inner", "outward", "inward", "up", "down", etc. should be understood as convenient terms and should not be understood as limiting terms.

[0032] In addition, terms such as "horizontal", "vertical", "hanging", etc. do not mean that the components are required to be absolutely horizontal or hanging, but can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0033] In the description of the present application, it should also be noted that unless otherwise clearly specified and limited, the terms "set", "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0034] As Figure 1 shown, an orthopedic surgical robot includes a workstation 1, a multi-axis robotic arm 2 ( Figure 1 only the end part thereof is shown in Figure 1 ), a passive two-link 3, a bone saw 4, a tracker 5, and a tracking bracket (not shown). Among them, the first end of the passive two-link 3 is fixed to the end of the multi-axis robotic arm 2, and the bone saw 4 is fixedly installed at the second end of the passive two-link 3. The bone saw 4 is equipped with a saw blade and a tracking bracket. The plane where the saw blade is located is called the bone saw plane, as shown by A in

[0035] . When the passive two-link 3 is stretched, the tracking bracket can always be within the tracking range of the tracker 5. When the passive two-link 3 is folded, the multi-axis robotic arm 2 automatically places the plane where the bone saw is located onto the osteotomy plane planned before the operation, and the user can stretch the two-link to complete the movement of the bone saw and complete the osteotomy operation. The tracker 5 and the tracking bracket cooperate to obtain the stretching length of the passive two-link 3. The workstation 1 is electrically connected to the multi-axis robotic arm 2, the bone saw 4, and the tracker 5 and includes a processor and a memory, and is used to control the multi-axis robotic arm 2, the bone saw 4, and the tracker 5 to complete corresponding operations according to a pre-designed computer program, such as moving, sawing bones, etc. Among them, the computer program is stored in the memory and completes the corresponding operations when executed by the processor, realizing an automatic calibration method for the bone saw plane of the orthopedic surgical robot. This method will be described in detail below.

[0036] The multi-axis robotic arm 2 can be a commercially available six-axis robotic arm, and its structure is well-known. For example, the multi-axis robotic arm 2 has six successively coupled joints, including a base part for realizing the rotation of the body, a shoulder for realizing the movement of the upper arm, an elbow for realizing the movement of the forearm, a first wrist for realizing the rotational movement of the wrist, a second wrist for realizing the up-and-down swing of the wrist, and a third wrist for realizing the circumferential movement of the wrist. The third wrist, as the end of the multi-axis robotic arm 2, is fixedly connected to the passive two-link 3.

[0037] The passive two-link 3 includes a first link and a second link that are hinged to each other so as to be able to stretch. Both the first link and the second link are rigid to reduce deformation. The first link and the second link can generally be made of stainless steel and its alloys.

[0038] The tracker 5 is usually an optical tracker (for example, a laser tracker), on which a light source and a tracking camera are installed. The tracking bracket is, for example, in the shape of a "cross" or an "X", and four retroreflective stickers are provided thereon. The light emitted by the light source on the tracker 5 is reflected by the retroreflective stickers on the tracking bracket and received by the tracking camera, so as to measure the stretching length of the passive two-link. The tracker 5 and the tracking bracket are commercially available.

[0039] Due to the weight of the bone saw 4 installed at the end of the passive two-link 3, during the process of stretching the passive two-link 3 from the folded state to the straight state, the passive two-link 3 will have a slight downward displacement in the horizontal direction due to gravity, resulting in an error in the bone saw surface, as Figure 3 shown. That is to say, the displacement error of the bone saw surface is related to the stretching length of the passive two-link 3 and the rotation angle of the robotic arm 2. In addition to designing the passive two-link 3 and selecting materials that are not easily deformed, it is necessary to be able to detect, calibrate, and correct the error of the bone saw surface caused thereby during the stretching use of the passive two-link 3. The following will refer to Figure 2 to describe a method for calibrating the bone saw surface of an orthopedic surgical robot of the present invention.

[0040] As Figure 2 shown, a method for calibrating the bone saw surface of an orthopedic surgical robot of the present invention may include the following steps:

[0041] S1: Provide a tracker and a tracking bracket, the tracking bracket is fixedly installed at the second end of the bone saw or the passive two-link, and the tracker cooperates with the tracking bracket to obtain the stretching length x of the passive two-link.

[0042] S2: Collect data, including the rotation angle θ of the end of the multi-axis robotic arm, the stretching length x of the passive two-link, and the distance d of the bone saw surface from the original position. The specific process is as follows:

[0043] Define the rotation angle of the end of the robotic arm as θ (0° ≤ θ ≤ 360°), and the ideal stretching of the passive two-link is a linear motion and parallel to the world horizontal plane. Set the ideal motion plane of the passive two-link parallel to the world plane, and at this time θ = 0. Stretch the passive two-link connected to the bone saw, and record in real time the distance between the plane where the saw blade of the moving bone saw is located (i.e., the saw surface of the bone saw) and the plane where the original saw blade of the bone saw is located (i.e., the original position of the saw surface of the bone saw) until the passive two-link is fully extended. Change the rotation angle θ of the end of the multi-axis robotic arm, and repeat the above process until enough data is collected. Among them, the distance d at which the saw surface of the bone saw leaves the original position is collected by a laser rangefinder, the stretching length x of the passive two-link is collected by an optical tracker; and the rotation angle θ of the end of the multi-axis robotic arm can be directly read from the multi-axis robotic arm itself or the workstation. Among them, the data volume of the rotation angle θ of the end of the multi-axis robotic arm is greater than 20, and the data volume corresponding to each rotation angle θ of the end of the multi-axis robotic arm is greater than 20.

[0044] S3: Process the collected data, and fit to obtain the relationship function d(x, θ) between the distance d at which the saw surface of the bone saw leaves the original position, the rotation angle θ of the end of the multi-axis robotic arm, and the stretching length x of the passive two-link. The specific process is as follows:

[0045] First, by processing a set of data when the rotation angle θ of the end of the multi-axis robotic arm is 0, fit to obtain the relationship function d(x) between the distance d at which the saw surface of the bone saw leaves the original position and the stretching length x of the passive two-link. d(x) can be expressed as:

[0046] d(x) = ax 2 + bx + c (1)

[0047] Among them, a, b, and c are constants, which can be obtained by solving equation (2) using the least squares method:

[0048]

[0049] Among them, d(x i ), i = 1, 2,..., N are collected by a laser rangefinder, x i , i = 1, 2,..., N are recorded by an optical tracker, where N represents the total number of collected data, and N > 20.

[0050] Secondly, when the rotation angle θ of the end of the multi-axis robotic arm changes continuously from 0° to 360°, construct the displacement equation d(x, θ) of the saw surface of the bone saw at different stretching lengths x of the passive two-link and different rotation angles θ of the end of the multi-axis robotic arm,

[0051] d(x, θ) = m + n × cosθ × d(x) (3)

[0052] Among them, m and n are constants, which can be obtained by solving Equation (4) using the least squares method:

[0053]

[0054] Among them, d(x, θ j ), j = 1, 2,..., M are obtained by collecting through a laser rangefinder, and x j , j = 1, 2,..., M are obtained by collecting through an optical tracker, and d(x j ) is calculated according to Equation (1), where j = 1, 2,..., M. Here, M represents the total number of collected data, and M > 20.

[0055] S4: Perform real-time calibration on the saw surface of the bone saw according to the relationship function d(x, θ). Specifically, during the operation, the distance of the saw surface of the bone saw from the original position is calculated according to Equation (3) by the rotation angle of the end of the multi-axis robotic arm and the stretching length of the passive two-link obtained in real time, so as to realize the calibration of the saw surface of the bone saw. Among them, the rotation angle θ of the end of the multi-axis robotic arm is obtained through the data of the multi-axis robotic arm itself, and the stretching length x of the passive two-link is obtained through an optical tracker.

[0056] It should be understood that although the fitting of the above relationship functions d(x) and d(x, θ) is implemented using the least squares method, those skilled in the art can use other well-known function fitting methods to implement.

[0057] The present invention stretches the passive two-link at different positions and records the position of the saw surface of the bone saw, calculates the error of the saw surface of the bone saw at different positions of the passive two-link, can correct in real time during the operation the error of the saw surface of the bone saw caused by the displacement deviation after stretching the passive two-link, reduce the occurrence of surgical accidents, and improve the surgical success rate.

[0058] The embodiments of the present application provide an orthopedic surgical robot, specifically an orthopedic surgical robot for total knee replacement surgery. The orthopedic surgical robot includes a processor and a memory, and the memory stores a computer program. Among them, when the processor executes the computer program, the method for calibrating the saw surface of the orthopedic surgical robot as described above is implemented. Preferably, the workstation of the orthopedic surgical robot is configured to include a memory storing the computer program and a processor capable of executing the computer program.

[0059] Exemplarily, the computer program may be divided into one or more modules / units, which are stored in the memory and executed by the processor to complete the method for verifying the saw surface of the bone saw of the orthopedic surgical robot of the present invention. The one or more modules / units may be a series of computer program instruction segments capable of completing specific functions, and these instruction segments are used to describe the execution process of the computer program in the robot.

[0060] The orthopedic surgical robot may include, but is not limited to, a processor and a memory. For example, it may also include input / output devices, network access devices, a bus, etc.

[0061] The processor may be a central processing unit (CPU), or may also be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc. The processor is the control center of the orthopedic surgical robot, and connects various parts of the entire robot through various interfaces and lines.

[0062] The memory may be used to store computer programs and / or modules. The processor realizes various functions of the orthopedic surgical robot by running or executing the computer programs and / or modules stored in the memory, and by calling the data stored in the memory. For example, real-time verification of the saw surface of the bone saw, bone sawing, etc. The memory may mainly include a program storage area and a data storage area. Among them, the program storage area may store an operating system, application programs required for at least one function (such as a sound playback function, an image playback function, etc.); the data storage area may store data created according to the use of the mobile phone (such as audio data, phone book, etc.). In addition, the memory may include high-speed random access memory, and may also include non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, at least one magnetic disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0063] In addition, an embodiment of the present application further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the bone saw surface verification method of the orthopedic surgical robot as described above can be implemented.

[0064] Wherein, the computer program includes computer program code, and the computer program code can be in the form of source code, object code, executable file or some intermediate form, etc. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disc, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electrical carrier signal, telecommunication signal, and software distribution medium, etc. It should be noted that the content included in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium does not include electrical carrier signals and telecommunication signals.

[0065] The preferred embodiments of the present invention have been described in detail above. However, it should be understood that after reading the above teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention. These equivalent forms also fall within the scope defined by the appended claims of the present application.

Claims

1. An orthopedic surgical robot, characterized in that, The orthopaedic surgical robot includes a workstation, a multi-axis robotic arm, a passive two-link, a bone saw, a tracker, and a tracking bracket. The first end of the passive two-link is fixed to the end of the multi-axis robotic arm, and the bone saw is fixedly installed at the second end of the passive two-link. The tracking bracket is fixedly installed on the bone saw or the second end of the passive two-link. The workstation is electrically connected to the multi-axis robotic arm, the bone saw, and the tracker and includes a processor and a memory. The memory stores a computer program. When the processor executes the computer program, the following bone saw surface verification steps are implemented: S1: The tracker cooperates with the tracking bracket to obtain the stretching length x of the passive two-link. S2: Data is collected, including the rotation angle θ of the end of the multi-axis robotic arm, the stretching length x of the passive two-link, and the distance d of the bone saw surface from the original position. S3: The collected data is processed, and a relationship function d(x,θ) between the distance d of the bone saw surface from the original position, the rotation angle θ of the end of the multi-axis robotic arm, and the stretching length x of the passive two-link is obtained by fitting. S4: During the operation, the distance d of the bone saw surface from the original position is calculated according to the relationship function d(x,θ) through the rotation angle θ of the end of the multi-axis robotic arm and the stretching length x of the passive two-link obtained in real time, so as to realize the verification of the bone saw surface.

2. The orthopedic surgical robot according to claim 1, wherein S3 Including: S31: When the rotation angle θ of the end of the multi-axis robotic arm is 0, fit the relationship function d(x) between the distance that the bone saw surface leaves the original position and the stretching length of the passive two-link, where d(x) = ax 2 + bx + c, where a, b, and c are constants; S32: For different rotation angles θ of the end of the multi-axis robotic arm, the relationship function d(x,θ) is obtained by fitting, where d(x,θ)=m + n×cosθ×d(x), and m and n are constants.

3. The orthopedic surgical robot according to claim 2, wherein Both S31 and S32 are implemented by least squares fitting.

4. The orthopaedic surgical robot according to claim 3, wherein The specific process of S31 is to construct the function d(x) = ax 2 + bx + c; collect the data d of the distance d that the saw surface of the bone saw leaves the original position through a laser rangefinder d(x i ), i = 1, 2,..., N, and collect the data x of the stretching length x of the passive two-link through the tracker x i , i = 1, 2,..., N, where N represents the total number of collected data, and N > 20; solve by the least squares method to obtain the coefficients a, b, and c.

5. The orthopedic surgical robot according to claim 3, wherein The specific process of S32 is to construct the function d(x, θ) = m + n×cosθ×d(x). The data d(x, θ j ), j = 1, 2,..., M, of the distance d that the saw surface of the bone saw deviates from the original position is collected by a laser rangefinder, and x j , j = 1, 2,..., M, is collected by the tracker, and d(x j ), j = 1, 2,..., M, is calculated according to the relational function of S31. Here, M represents the total number of collected data, and M > 20. The coefficients m and n are obtained by the least squares method .

6. The orthopaedic surgical robot according to claim 1, wherein, The multi-axis robotic arm is a six-axis robotic arm.

7. The orthopedic surgical robot according to claim 1, wherein The tracker is an optical tracker.

8. The orthopaedic surgical robot according to claim 1, wherein The orthopaedic surgical robot is used for total knee replacement surgery.

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