A perspective following method of a bone model and a bone registration system

Abstract

The application provides a bone model view following method and a bone registration system. The bone model view following method obtains a current pose of a trackable element; and controls a bone model displayed on a display to rotate based on the current pose of the trackable element, so as to adjust a display orientation of the bone model. By performing the bone model view following method in a bone registration process, the display orientation of the bone model on the display can be automatically adjusted according to the pose change of the trackable element, without the need of an additional operator to manually adjust the display orientation of the bone model, thereby improving the efficiency of bone registration.

Description

Technical Field

[0001] This invention belongs to the field of medical device technology, specifically relating to a viewpoint following method for bone models and a bone registration system. Background Technology

[0002] In existing techniques, bone registration during arthroplasty typically requires two operators. One operator manipulates a tracking element to bring it into contact with the bone surface, thereby determining the location of the actual registration point. During this process, this operator locates the actual registration point using the planned registration points on the bone model displayed on a monitor. The other operator controls a computer at the control terminal to adjust the orientation of the bone model on the monitor, facilitating the operator manipulating the tracking element in locating the actual registration point. This method often requires the computer operator to make multiple and lengthy adjustments to position the bone model appropriately, resulting in low registration efficiency. Summary of the Invention

[0003] The purpose of this invention is to provide a viewpoint following method for bone models and a bone registration system to improve the efficiency of bone registration.

[0004] To achieve the above objectives, the present invention provides a viewpoint following method for a bone model, comprising:

[0005] Obtain the current pose of the trackable element, and determine the position of the actual registration point on the real bone based on the current pose of the trackable element;

[0006] Obtain the position of the first planned registration point on the bone model corresponding to the currently determined actual registration point;

[0007] Obtain the current first normal vector of the target plane, the target plane including the first planning registration point;

[0008] The rotation of the bone model is controlled based on the second normal vector of the display screen showing the bone model and the current first normal vector.

[0009] Optionally, the trackable element is used to contact the surface of the real bone to determine the location of the actual registration point.

[0010] Optionally, the step of obtaining the current first normal vector of the target plane includes:

[0011] On the bone model, obtain the position of the second planning registration point and the position of the third planning registration point that are closest to the first planning registration point;

[0012] The first normal vector of the target plane is obtained based on the positions of the first planning registration point, the second planning registration point, and the third planning registration point. The target plane also includes the second planning registration point and the third planning registration point.

[0013] Optionally, the step of controlling the rotation of the bone model based on the second normal vector of the display screen displaying the bone model and the current first normal vector includes:

[0014] The first axis of rotation is obtained based on the second normal vector and the current first normal vector;

[0015] Obtain the first angle between the second normal vector and the current first normal vector;

[0016] The bone model is controlled to rotate around the first rotation axis, and the difference between the rotation angle of the bone model and the first angle is within a first preset range.

[0017] Optionally, the viewpoint following method for the bone model also includes:

[0018] Determine whether the relationship between the initial axial vector of the bone model and the display screen conforms to a predetermined relationship;

[0019] If not, the bone model is rotated until the relationship between the axial vector of the bone model and the display screen of the monitor conforms to the predetermined relationship.

[0020] Optionally, the viewpoint following method for the bone model also includes:

[0021] Obtain the second angle between the second normal vector and the initial axial vector of the bone model;

[0022] Determine whether the second angle is within the second preset range;

[0023] If so, it is determined that the relationship between the axial vector of the bone model and the display screen conforms to the predetermined relationship;

[0024] If not, then based on the second normal vector of the display screen and the initial axial vector of the bone model, a second rotation axis is obtained, and the bone model is controlled to rotate around the second rotation axis until the relationship between the axial vector of the bone model and the display screen of the monitor conforms to the predetermined relationship.

[0025] Optionally, the step of obtaining the axial vector of the bone model includes:

[0026] Obtain the point cloud of the surface of the initial bone model;

[0027] Obtain the covariance matrix of the point cloud;

[0028] Obtain the eigenvalues ​​and eigenvectors of the covariance matrix, and use the eigenvector corresponding to the largest eigenvalue as the axial vector of the bone model.

[0029] To achieve the above objectives, the present invention also provides a bone registration system, comprising: a trackable element, a positioning device, and a control device;

[0030] The positioning device is used to obtain the current pose of the trackable element when it contacts the real bone surface, so as to determine the position of the actual registration point.

[0031] The control device is communicatively connected to the positioning device. The control device includes a memory and a processor. The memory stores an executable program, and the processor is configured to execute the executable program stored in the memory. The executable program performs the viewpoint following method of the bone model as described above.

[0032] Optionally, the bone registration system further includes a switch, which is communicatively connected to the trackable element and the control device. When the switch meets a corresponding set condition, it triggers the control device to obtain the current pose of the trackable element to determine the location of the actual registration point.

[0033] Optionally, the trackable element includes a support and a target ball. The support includes a body and several branches. One end of the body is a pointed tip. The several branches are connected to the body. The target ball is provided on both the branches and the body.

[0034] The switch is located on the main body. Pressing or touching the switch generates a trigger signal. The positioning device collects the current pose of the trackable element based on the trigger signal to determine the location of the actual registration point.

[0035] Optionally, the bone registration system further includes: a display screen, which is communicatively connected to the control device; the control device is also used to generate a virtual model of the traceable element;

[0036] When the trackable element comes into contact with the actual registration point, the virtual model on the display screen approaches and coincides with the corresponding planned registration point on the bone model.

[0037] Compared with the prior art, the viewpoint following method and bone registration system of the bone model of the present invention have the following advantages:

[0038] The aforementioned view-following method for bone models includes: acquiring the current pose of a trackable element; determining the position of an actual registration point on the real bone based on the current pose of the trackable element; acquiring the position of a first planned registration point on the bone model corresponding to the currently determined actual registration point; acquiring the current first normal vector of a target plane, the target plane including the first planned registration point; controlling the rotation of the bone model based on a second normal vector of the display plane displaying the bone model and the current first normal vector to adjust the display orientation of the bone model; by executing the view-following method for bone models during bone registration, the display orientation of the bone model on the display can be automatically adjusted according to the pose change of the trackable element, without the need for an additional operator to manually adjust the display orientation of the bone model, thus improving the efficiency of bone registration. Attached Figure Description

[0039] The accompanying drawings are provided to better understand the invention and are not intended to unduly limit the scope of the invention. Wherein:

[0040] Figure 1 This is a schematic diagram illustrating an application scenario of the bone registration system provided by the present invention according to an embodiment;

[0041] Figure 2 This is a schematic diagram showing the end of a tracking element abutting against the surface of bone when the bone registration system provided by the present invention according to an embodiment is applied to joint replacement surgery and bone registration is performed;

[0042] Figure 3 This is a schematic diagram illustrating the contact between the end of a tracking element and the surface of bone when the bone registration system provided by this invention according to another embodiment is applied to joint replacement surgery and bone registration is performed. Figure 3 and Figure 2 The difference lies in the position where the end of the trackable element rests against the surface of the bone;

[0043] Figure 4 This is a schematic diagram illustrating the contact between the end of a tracking element and the surface of bone when the bone registration system provided by this invention according to another embodiment is applied to joint replacement surgery and bone registration is performed. Figure 4 The orientation of the bones in Figure 2 and Figure 3 different;

[0044] Figure 5 yes Figure 4 Enlarged diagram of point A in the diagram;

[0045] Figure 6 This is a schematic diagram of the structure of a trackable element in a bone registration system provided by the present invention according to an embodiment;

[0046] Figure 7This is a schematic diagram of the display screen of the bone registration system provided by the present invention according to an embodiment, when applied to joint replacement surgery and performing bone registration. The diagram shows a bone model and the planned registration points on the bone model.

[0047] Figure 8 This is a schematic diagram of the display screen of the bone registration system provided by the present invention when it is applied to joint replacement surgery and bone registration is performed. The figure shows a virtual model of the trackable element generated based on the pose information of the current trackable element.

[0048] Figure 9 This is a more detailed flowchart of a method for adjusting the perspective of a bone model performed by the control device of a bone registration system provided according to an embodiment of the present invention. Step S00 is not shown in the figure.

[0049] Figure 10 This is a schematic diagram of the first planned registration point, the second planned registration point, and the third planned registration point determined on the bone model in the perspective adjustment method of the bone model executed by the control device of the bone registration system provided according to an embodiment of the present invention, and a schematic diagram of the plane in which the first planned registration point, the second planned registration point, and the third planned registration point are located.

[0050] Figure 11 This is a schematic diagram of a plane obtained by the perspective adjustment method of a bone model executed by the control device of the bone registration system provided according to an embodiment of the present invention.

[0051] Figure 12 This is a schematic diagram of the plane and its first normal vector obtained in the perspective adjustment method of the bone model executed by the control device of the bone registration system provided according to an embodiment of the present invention.

[0052] Figure 13 This is a schematic diagram showing the positional relationship between the first normal vector and the bone model in the perspective adjustment method of the bone model executed by the control device of the bone registration system provided according to an embodiment of the present invention.

[0053] Figure 14 This is a schematic diagram of the second normal vector of the display screen in the bone model viewing angle adjustment method executed by the control device of the bone registration system provided according to an embodiment of the present invention.

[0054] Figure 15 This is a flowchart of a method for adjusting the perspective of a bone model performed by the control device of a bone registration system provided according to an embodiment of the present invention, showing step S00.

[0055] Figure 16 This is a schematic diagram of the principal axis of the bone model obtained in the perspective adjustment method of the bone model executed by the control device of the bone registration system provided according to another embodiment of the present invention. Detailed Implementation

[0056] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show components related to the present invention and are not drawn according to the actual number, shape, and size of components in the actual implementation. In the actual implementation, the type, quantity, and proportion of each component can be arbitrarily changed, and the component layout may also be more complex.

[0057] Furthermore, while each embodiment described below possesses one or more technical features, this does not imply that users of the present invention must simultaneously implement all technical features in any embodiment, or can only separately implement some or all technical features in different embodiments. In other words, provided it is feasible, those skilled in the art can, based on the disclosure of the present invention and depending on design specifications or implementation requirements, selectively implement some or all technical features in any embodiment, or selectively implement a combination of some or all technical features in multiple embodiments, thereby increasing the flexibility in implementing the present invention.

[0058] The purpose of this invention is to provide a bone registration system that can be used in bone and joint replacement surgery. During the bone registration process, the system can control the bone model on the display to automatically rotate to a display position that is easy for the operator to observe, without the need for additional assistants to manually operate the bone model rotation, thus simplifying the surgical operation and improving registration efficiency.

[0059] To make the objectives, advantages, and features of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clearly illustrate the objectives of the embodiments of the present invention. The same or similar reference numerals in the drawings represent the same or similar parts.

[0060] Figures 1 to 5 This diagram illustrates a scenario where the bone registration system provided by an embodiment of the present invention is applied to joint replacement surgery. Figures 1 to 5As shown, the bone registration system includes at least a trackable element 10, a positioning device 20, and a control device. The trackable element 10 is used to perform corresponding operations on the surface of bone 1 to determine the position of the actual registration point 2 on the surface of bone 1 in the coordinate system of the positioning device 20. The positioning device 20 is communicatively connected to the control device and is used to acquire the pose information of the trackable element 10 and send the pose information of the trackable element 10 to the control device. It should be understood that pose includes position and orientation.

[0061] In some embodiments, the trackable element 10 is an optical target. For example... Figure 6 As shown, the trackable element 10 includes a body 11, several branches 12, and several reflective spheres 13. Optionally, the body 11 is generally pen-shaped, with one end serving as a detection tip. There can be three branches 12, with two branches 12 positioned at an angle at the end of the body 11 furthest from the tip, and the other branch 12 positioned in the middle of the body 11. There are four reflective spheres 13, with three spheres 13 positioned on the three branches 12 and the other sphere 13 positioned on the body 11. In practice, this embodiment of the invention does not impose particular limitations on the number, distribution, or length of the branches 12, or the number and distribution of the reflective spheres 13, as long as those skilled in the art can determine the pose of the detection tip of the trackable element 10 using appropriate algorithms based on the number and arrangement of the target spheres 13, and thus determine the position of the detection tip of the body 11 in the patient coordinate system. It can be understood that when the trackable element 10 is an optical target, the positioning device 20 is correspondingly an optical positioning instrument. The operation performed by the trackable element 10 on the surface of the bone 1 is that the detection end of the trackable element 10 abuts against the surface of the bone 1. In an alternative embodiment, the trackable element 10 may also be a magnetic target, and accordingly, the positioning device 20 is a magnetic positioning device.

[0062] The control device includes a processor for implementing various functions described in the embodiments of the present invention, such as calculation and control. In some embodiments, the control device is a computer, which may be located on a navigation vehicle 30 (e.g., Figure 1 (As shown). In other embodiments, the control device is located in a separate device or in a remote device. In still other embodiments, a portion of the control device is located in the navigation carriage 30, and a remaining portion is located in one or more other separate devices. This embodiment of the invention is not limited in this respect.

[0063] Prior to bone registration, preoperative imaging data is transmitted and stored in the control device for use during bone registration and preoperative planning. Preoperative imaging data can be scan data obtained using any existing imaging equipment such as CT, MRI, ultrasound, etc. The control device can use the preoperative imaging data to obtain a bone model of the patient's target site (e.g., Figure 7 and Figure 8 As shown), by performing preoperative planning on bone model 01, it is possible to obtain results such as... Figure 7 and Figure 8 The multiple planned registration points 02 are shown.

[0064] Optionally, please return to the reference. Figure 1 The bone registration system also includes a display 40, which is communicatively connected to a control device. The display 40 is used to display the bone model 01 and the planned registration points 02 on the bone model 01. The display 40 is also used to display a virtual model 03 of the trackable element 10 (e.g., ...). Figure 8 (As shown).

[0065] During bone registration, the operator, based on the planned registration point 02, holds the trackable element 10 and performs an actual feature point 2 acquisition operation on the surface of the patient's bone 1 to acquire the position of the corresponding actual registration point 2. Then, the positioning device 20 obtains the pose information of the trackable element 10 by tracking it. The control device is configured to receive the pose information of the trackable element 10 acquired by the positioning device 20 upon triggering by a predetermined component, thereby obtaining the position of the actual registration point 2, and registering the planned registration point 02 and the actual registration point 2 using any suitable registration algorithm to obtain the final transformation matrix, achieving the registration of the patient's physical space coordinate system and the preoperative image coordinate system. It can be understood that during the process of the trackable element 10 acquiring the actual registration point 2 on the bone surface, the control device also generates a virtual model 03 of the trackable element 10 based on its current pose, displays the virtual model 03 on the display 40, and controls the virtual model 03 to approach and coincide with the corresponding planned registration point 02 on the bone model 01 when the trackable element 10 contacts the actual registration point 2.

[0066] This invention does not specifically limit the predetermined components; in some embodiments, such as Figure 6As shown, the predetermined component is a switch 14 located on the trackable element 1, and the switch 14 is communicatively connected to the control device. When the state of the switch 14 meets the set conditions, it can trigger the control device to receive the position and orientation information of the trackable element 10 obtained by the positioning device 20. The switch 14 is, for example, a manual switch, specifically a push-button switch. The set conditions include pressing the push-button switch to achieve conduction corresponding to the preset rules, such as a short press of the switch 14 to confirm the actual registration point 2, thereby allowing the control device to obtain the position and orientation information of the trackable element 1 and the position information of the actual registration point 01. The switch 14 is set at any position on the trackable element 1, preferably in a position that is easy for the operator to hold. The setting of the switch 14 facilitates real-time operation by the operator without the need for assistance from other operators, improving work efficiency and operating experience. It can be understood that the switch 14 is used to receive instructions input by the operator to trigger the control device to perform corresponding operations. In addition to the short press of the switch 14 to trigger the control device to obtain the actual registration point 2, it can also include a long press of the switch 14 to trigger the control device to delete the confirmed actual registration point 2, etc. In an alternative embodiment, the switch may also be a touch switch, and the setting conditions include the touch switch. Furthermore, please refer to [link / reference needed]. Figure 6 The trackable element 10 also includes a power supply 15 and a circuit board 16. The circuit board 16 is equipped with various functional components for signal processing and transmission, and the power supply 15 supplies power to the circuitry in the circuit board 16. The switch 14 is electrically connected to the circuitry on the circuit board 16. By performing corresponding operations, the functional components on the circuit board 16 are activated. For example, a short press of the switch 14 causes the functional components on the circuit board 16 to perform signal processing and transmit the signal to the control device, enabling the control device to obtain the current position of the actual registration point 2.

[0067] In an alternative embodiment, the predetermined component may also be a foot pedal (not shown) that is communicatively connected to the control device. When the state of the foot pedal meets the set conditions, such as when the foot pedal is pressed, the control device can be triggered to receive the pose information of the actual registration point 2 determined by the trackable element 1 obtained by the positioning device 2.

[0068] The control device also includes a memory, which is communicatively connected to the processor and stores an executable program. During bone registration, the processor is also configured to execute the executable program stored in the memory, thereby executing a viewpoint adjustment method for a bone model. The viewpoint adjustment method for the bone model includes: controlling the bone model 01 to rotate to the target display orientation based on the current pose of the trackable element 10. After the bone model 01 is rotated to the target display orientation, the operator can easily view the planned registration point 02 on the bone model 01.

[0069] That is, the bone model 01 can automatically rotate following the pose of the trackable element 1 and switch to a display position that is convenient for the operator to observe the planned registration point 02. In this way, during the bone registration process, there is no need to equip other operators to manually adjust the display position of the bone model 01 according to the pose of the trackable element 10, thereby improving work efficiency and operating experience.

[0070] In one exemplary embodiment, such as Figure 9 As shown, the method for adjusting the viewpoint of a bone model can specifically include the following steps:

[0071] Step S10: Obtain the current pose of the trackable element 10.

[0072] Step S20: Based on the current pose of the trackable element 10, obtain the position of the actual registration point 2 that the trackable element 10 currently determines on the surface of the real bone 1.

[0073] Step S30: Obtain the first planned registration point P on bone model 01 corresponding to the currently determined actual registration point 2 (e.g., Figure 10 (as shown in the image)

[0074] Step S40: Obtain the current first normal vector of the target plane 04. The target plane 04 includes the first planning registration point P, that is, the first planning registration point P is a point on the target plane 04.

[0075] Step S50, based on the second normal vector n2 of the display screen of the display 40 (e.g. Figure 14 As shown, the first normal vector n1 controls the rotation of bone model 01. It can be understood that during bone registration, the operator needs to select multiple actual registration points 2 on the surface of bone 1. Each time the operator selects an actual registration point 2, the control device executes steps S10 to S50 once. In other words, the control device repeatedly executes steps S10 to S50 in a loop, with the specific number of executions being the same as the number of actual registration points 2.

[0076] The optional implementation methods of steps S10 to S50 will be further described below.

[0077] In step S10, the positioning device 20 first acquires the current pose of the trackable element 10. Then, the operator briefly presses the switch 14 on the trackable element 10 to trigger the control device to receive the current pose of the trackable element 10 acquired by the positioning device 20. Subsequently, the control device obtains the position of the currently determined actual registration point 2 based on the current pose of the trackable element 10 using conventional methods, and obtains the position of the first planned registration point P corresponding to the currently determined actual registration point 2 (that is, the control device executes steps S20 and S30 using conventional methods).

[0078] like Figure 9 As shown, step S40 includes steps S41 and S42. Step S41 includes obtaining the positions of the two planning registration points 02 on the bone model 01 that are closest to the first planning registration point P. These two planning registration points are located at... Figure 10 The points are identified as the second planning registration point Q and the third planning registration point R. Step S42 includes obtaining the target plane 04 based on the positions of the first planning registration point P, the second planning registration point Q, and the third planning registration point R. Figures 10 to 13 The current first normal vector n1 (as shown) Figure 12 and Figure 13 (As shown). In this way, target plane 04 is the plane containing the first planning registration point P, the second planning registration point Q, and the third planning registration point R.

[0079] Step S41 can be executed using any suitable algorithm, such as the KNN algorithm. Specifically, it can be based on a kd-tree (k-dimensional tree) to obtain the second planning registration point Q and the third planning registration point R. The general process includes: First, constructing a kd-tree, where the first planning registration point P is the target point. Then, recursively searching the next node from the root node until a leaf node, calculating the approximate nearest point of the target point based on the relationship between the target point and the current node in the partition dimension. Then, backtracking is performed. During the backtracking process, if a node closer to the target point is found, the current approximate nearest point is updated until the backtracking ends, and the nearest point is determined. That is, the second planning registration point Q and the third planning registration point R are found.

[0080] To find the plane from three points, we can take the product of their vectors as the normal vector. Thus, step S42 can be achieved by finding the vector between the first planning registration point P and the second planning registration point Q. The vector between the first planning registration point P and the third planning registration point R This is achieved through a vector product, where (x1, y1, z1) are the coordinates of the first planning registration point P, (x2, y2, z2) are the coordinates of the second planning registration point Q, and (x3, y3, z3) are the coordinates of the third planning registration point R. Therefore, the formula for calculating the current first normal vector n1 is: The current positional relationship between the first normal vector n1 and the bone model 01 is as follows: Figure 13 As shown.

[0081] Those skilled in the art will know that the second normal vector n2 is a known quantity. Therefore, when executing step S50, the control device can directly call the second normal vector n2.

[0082] In a preferred embodiment, the target display orientation refers to the orientation when the first normal vector n1 and the second normal vector n2 are parallel to each other. Therefore, step S50 can end when the bone model 01 is rotated until the first normal vector and the second normal vector n2 are parallel to each other. That is, after the bone model 01 is rotated, the first normal vector n1 and the second normal vector n2 are parallel to each other.

[0083] Therefore, the specific operations of step S50 may include steps S51, S52 and S53.

[0084] Step S51 includes obtaining the first rotation axis p based on the second normal vector n2 and the current first normal vector n1. The first rotation axis p is equal to the vector product of the second direction vector n2 and the current first normal vector n1, that is, p = n1 × n2.

[0085] Step S52 includes obtaining the first angle between the second normal vector n2 and the current first normal vector n1, and denoting the first angle as α. The value of α can be obtained from the dot product of the second normal vector n2 and the current first normal vector n1, and the calculation formula is α = arccos(n2·n1).

[0086] Step S53 includes controlling the bone model 01 to rotate around the first rotation axis p, and the rotation angle is α.

[0087] Alternatively, the target orientation can also be the orientation when the first normal vector n1' and the second normal vector n2 of the bone model 01 are basically parallel after rotation, for example, the angle between the first normal vector n1' and the second normal vector n2 after rotation is not greater than a preset deviation ΔX1. In this way, the allowable rotation angle of the bone model 01 when rotating around the first rotation axis p is ([α-ΔX1, α+ΔX1]). In other words, the difference between the rotation angle of the bone model 01 around the first rotation axis p and the first angle α is within [-ΔX1, ΔX1]. The specific value of the first preset deviation ΔX1 is set by the operator according to actual needs.

[0088] It should be noted that the "current first normal vector n1" here refers to the first normal vector of the bone model 01 before rotation.

[0089] Typically, at the start of bone registration, the operator expects the relationship between the axis of the bone model 01 and the display screen of the monitor 40 to conform to a predetermined relationship. Therefore, as follows... Figure 15 As shown, the bone model perspective adjustment method also includes step S00, performed before the operator holds the trackable element 10 against the surface of the bone 1 to determine the first actual registration point 2 (i.e., before bone registration begins). Step S00 includes determining the axial vector n3 of the initial bone model 01 (e.g., ...). Figure 16The operator checks whether the relationship between the bone model 01 and the display screen of the monitor 40 conforms to a predetermined relationship. If yes, the operator can directly use the trackable element 10 to select the actual registration point 2, and the control device executes steps S10 to S50. If no, the control device first controls the bone model 01 to rotate until the relationship between the axial vector of the bone model 01 and the display screen of the monitor 40 conforms to a predetermined relationship. Then, the operator uses the trackable element 10 to select the actual registration point 2, and the control device executes steps S10 to S50.

[0090] In one optional embodiment, the predetermined relationship is that the axis of the bone model 01 is perpendicular to the second normal vector n2. It should be understood that the perpendicularity of the axis of the bone model 01 to the display screen of the display 40 includes both absolute perpendicularity and substantially perpendicularity. Generally, as long as the angle between the axis of the bone model 01 and the second normal vector n2 of the display screen of the display 40 is within a preset range [-ΔX2, ΔX2], the axial vector of the bone model 01 is considered perpendicular to the display screen of the display 40. ΔX2 can be set by the operator according to actual needs.

[0091] Step S00 specifically includes the following steps S01, S02, S03, and S04. Step S01 includes obtaining a second angle between the second normal vector n2 and the axial vector n3 of the initial bone model 01, denoted as β. Step S02 includes determining whether β is within [-ΔX2, ΔX2]. If yes, the control device does not need to execute steps S03 and S04; otherwise, the control device continues to execute steps S03 and S04. Step S03 includes obtaining a second rotation axis q based on the second normal vector n2 and the axial vector n3 of the initial bone model 01. Step S04 includes controlling the bone model 01 to rotate around the second rotation axis q until the axial vector of the bone model 01 is perpendicular to the second vector n2. Ideally, the rotation angle of the bone model 01 around the second rotation axis q is β. However, in reality, the rotation angle of the bone model 01 around the second rotation axis q is within ([β-ΔX2, β+ΔX2]). Therefore, it is assumed that the axis of the rotated bone model 01 is perpendicular to the display screen of the display 40.

[0092] It can be understood that the value of β can be obtained by the inner product of the second normal vector n2 and the axial vector n3 of the initial bone model 01, and the calculation formula is β = arccos(n2·n3). The second rotation axis q can be obtained by the vector product of the second normal vector n2 and the axial vector n3 of the initial bone model 01, and the calculation formula is q = n3 × n2.

[0093] The initial bone model 01 can be obtained using principal component analysis (PCA). The specific steps are as follows:

[0094] First, obtain the point cloud of the surface of the initial bone model 01. The point cloud includes n points, and the coordinates of each point are (x, y, y). i y i , z i ), i = 1, 2, ..., n. Thus, the point cloud can be represented using a matrix as: M = [m1, m2, ..., mn]. n ] T ,m i It means (x) i y i , z i ).

[0095] Then, obtain the covariance matrix C of the point cloud. in, This represents the average coordinates of all points in the point cloud.

[0096] Finally, the eigenvalues ​​and eigenvectors of the covariance matrix C are calculated based on the formula dec(C-λI)=0, and the eigenvector corresponding to the largest eigenvalue is used as the axial vector n3 of the initial bone model 01. In the formula, λ represents the eigenvalue of the covariance matrix C, and I represents the identity matrix.

[0097] Furthermore, embodiments of the present invention also provide a computer-readable storage medium having a program stored thereon, which, when executed, performs the aforementioned method for adjusting the viewpoint of the bone model.

[0098] While the present invention has been disclosed above, it is not limited thereto. Those skilled in the art can make various modifications and variations to the present invention without departing from its spirit and scope. Therefore, if such modifications and variations fall within the scope of the claims and their equivalents, the present invention also intends to include such modifications and variations.

Claims

1. A viewpoint following method for a bone model, characterized in that, include: Obtain the current pose of the trackable element, and determine the position of the actual registration point on the real bone based on the current pose of the trackable element; Obtain the position of the first planned registration point on the bone model corresponding to the currently determined actual registration point; Obtain the current first normal vector of the target plane, the target plane including the first planning registration point, the second planning registration point and the third planning registration point, the second planning registration point and the third planning registration point are the two planning registration points on the bone model that are closest to the first planning registration point; The bone model is rotated to the target display orientation based on the second normal vector of the display screen showing the bone model and the current first normal vector; At the target display orientation, the first normal vector is parallel to the second normal vector.

2. The viewpoint following method for a bone model according to claim 1, characterized in that, The trackable element is used to contact the surface of the real bone to determine the location of the actual registration point.

3. The viewpoint following method for a bone model according to claim 1, characterized in that, The step of obtaining the current first normal vector of the target plane includes: obtaining the position of the second planning registration point and the position of the third planning registration point on the bone model; and obtaining the current first normal vector of the target plane based on the position of the first planning registration point, the position of the second planning registration point and the position of the third planning registration point.

4. The viewpoint following method for a bone model according to claim 1, characterized in that, The steps of controlling the rotation of the bone model based on the second normal vector of the display screen showing the bone model and the current first normal vector include: The first axis of rotation is obtained based on the second normal vector and the current first normal vector; Obtain the first angle between the second normal vector and the current first normal vector; The bone model is controlled to rotate around the first rotation axis, and the difference between the rotation angle of the bone model and the first angle is within a first preset range.

5. The viewpoint following method for a bone model according to claim 1, characterized in that, Also includes: Determine whether the relationship between the initial axial vector of the bone model and the display screen conforms to a predetermined relationship; If not, the bone model is rotated until the relationship between the axial vector of the bone model and the display screen of the monitor conforms to the predetermined relationship.

6. The viewpoint following method for a bone model according to claim 5, characterized in that, Also includes: Obtain the second angle between the second normal vector and the initial axial vector of the bone model; Determine whether the second angle is within the second preset range; If so, then it is determined that the relationship between the axial vector of the bone model and the display screen conforms to the predetermined relationship; If not, then based on the second normal vector of the display screen and the initial axial vector of the bone model, a second rotation axis is obtained, and the bone model is controlled to rotate around the second rotation axis until the relationship between the axial vector of the bone model and the display screen of the monitor conforms to the predetermined relationship.

7. The viewpoint following method for a bone model according to claim 5 or 6, characterized in that, The steps for obtaining the axial vector of the bone model include: Obtain the point cloud of the surface of the initial bone model; Obtain the covariance matrix of the point cloud; Obtain the eigenvalues ​​and eigenvectors of the covariance matrix, and use the eigenvector corresponding to the largest eigenvalue as the axial vector of the bone model.

8. A bone registration system, characterized in that, include: Trackable components, positioning devices, and control devices; The positioning device is used to obtain the current pose of the trackable element when it contacts the real bone surface, so as to determine the position of the actual registration point. The control device is communicatively connected to the positioning device. The control device includes a memory and a processor. The memory stores an executable program, and the processor is configured to execute the executable program stored in the memory. The executable program performs the viewpoint following method for the bone model as described in any one of claims 1-7.

9. The bone registration system according to claim 8, characterized in that, It also includes a switch, which is communicatively connected to the trackable element and the control device. When the switch meets the corresponding set conditions, it triggers the control device to obtain the current pose of the trackable element to determine the location of the actual registration point.

10. The bone registration system according to claim 9, characterized in that, The trackable element includes a support and a target ball. The support includes a body and several branches. One end of the body is a pointed tip. The several branches are connected to the body. The target ball is provided on both the branches and the body. The switch is located on the main body. Pressing or touching the switch generates a trigger signal. The positioning device collects the current pose of the trackable element based on the trigger signal to determine the location of the actual registration point.

11. The bone registration system according to claim 10, characterized in that, Also includes: The display screen is communicatively connected to the control device; the control device is also used to generate a virtual model of the traceable element. When the trackable element comes into contact with the actual registration point, the virtual model on the display screen approaches and coincides with the corresponding planned registration point on the bone model.

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