Method and system for constructing three-dimensional real force line

Abstract

The application provides a three-dimensional real force line construction method and system, which comprises the following steps: collecting lower limb images of a human body walking on or standing on a pressure measuring area by a stereoscopic image shooting device, wherein the lower limb images comprise images of the marking structure and the pressure measuring device; calculating a center point of a hip joint according to the marking structure on the lower limb images; calculating a standing pressure center point according to a measuring mark point; calculating a standing pressure center point on the lower limb images according to the standing pressure center point and the measuring mark point distribution; and connecting the center point of the hip joint and the standing pressure center point on the lower limb images to obtain a real force line. The method can construct a real force line, judge whether the lower limb force line has problems including varus deformity and valgus deformity, accurately evaluate the stress offset of the medial and lateral sides and the front and back sides of the knee joint and the ankle joint, and thus more accurately guide the correction of the force line.

Description

Technical Field

[0001] This invention relates to the technical field of force line construction, and in particular to a method and system for constructing three-dimensional realistic force lines. Background Technology

[0002] The lower limb force line is an imaginary straight line originating from the center of rotation of the femoral head and ending at the midpoint between the medial and lateral malleoli, representing the biomechanical transmission path of a normal human lower limb in a weight-bearing position. Clinically, the diagnosis of joint pain, preoperative diagnosis, surgical planning, and postoperative confirmation for surgeries such as osteotomy and joint replacement all require lower limb force line data as a reference standard. However, current lower limb force lines have traditionally been based on the line connecting the center of rotation of the femoral head and the midpoint between the medial and lateral malleoli. In reality, this is merely a mechanical axis, not a force transmission line. Based on this mechanical axis, the force deviation on the medial and lateral, and anterior and posterior sides of the knee and ankle joints cannot be accurately assessed. Insufficient or excessive force line correction can lead to surgical failure. Summary of the Invention

[0003] The purpose of this invention is to provide a method and system for constructing three-dimensional real force lines, which can accurately guide the correction of force lines and ensure better surgical results.

[0004] To achieve the above objectives, in a first aspect, the present invention provides a method for constructing a three-dimensional true force line, based on a pressure measuring device and a stereoscopic image capturing device. The pressure measuring device is provided with i measuring marker points, which are sequentially connected to form a pressure measuring area, where i is greater than or equal to 3. The method includes: fixing a marker structure for optical positioning on the lower limb of a human body; acquiring images of the lower limb of a human body walking or standing on the pressure measuring area using the stereoscopic image capturing device, the lower limb images including the marker structure and the image of the pressure measuring device; calculating the center point of the hip joint based on the marker structure on the lower limb image; calculating the standing pressure center point based on the measuring marker points; calculating the pressure center point of the standing pressure center point on the lower limb image based on the distribution of the standing pressure center point and the measuring marker points; and connecting the center point of the hip joint and the pressure center point on the lower limb image to obtain a true force line.

[0005] The beneficial effects of the method for constructing three-dimensional true force lines provided by this invention are as follows: Based on the combination of pressure measurement equipment and stereoscopic image acquisition equipment, the method acquires lower limb images of a human walking or standing on a pressure measurement area using stereoscopic image acquisition equipment. Based on the marked structures on the lower limb images, the center point of the hip joint is calculated. Based on the measured marker points, the standing pressure center point is calculated. Based on the distribution of the standing pressure center point and the measured marker points, the pressure center point of the standing pressure center point on the lower limb image is calculated. Then, the center point of the hip joint and the pressure center point on the lower limb image are connected to obtain the true force lines. This allows for accurate evaluation of the force offset on the medial and lateral sides and anterior and posterior sides of the knee and ankle joints, thereby providing more accurate guidance for force line correction and ensuring better surgical outcomes.

[0006] Optionally, fixing the marker structure for optical positioning on the human lower limb includes: fixing the marker structure to the femur; calculating the center point of the hip joint based on the femoral marker structure on the lower limb image includes: obtaining the position coordinates (x, y) of the marker structure fixed to the distal end of the femur in different posture states. i y i , z i The position coordinates are in the three-dimensional coordinate system captured by the stereoscopic image capturing device; the position coordinates (a, b, c) of the center point of the hip joint satisfy the formula:

[0007] (x i -a) 2 +(y i -b) 2 +(z i -c) 2 =r 2 ;

[0008] The coordinates (a, b, c) of the center point of the hip joint were calculated by fitting the center of the sphere using the least squares method.

[0009] Optionally, when the stereoscopic image capturing device acquires images of the lower limbs of a person standing on the pressure measurement area, it includes: using a probe tool with an optical positioning structure to obtain the medial and lateral points of the knee joint and the medial and lateral points of the ankle joint; calculating the center point of the knee joint and the center point of the ankle joint based on the medial and lateral points of the knee joint and the medial and lateral points of the ankle joint; after obtaining the true force line, it includes: determining whether there are problems such as varus deformity and valgus deformity in the lower limb force line based on the center point of the hip joint, the center point of the knee joint, the center point of the ankle joint and the pressure center point on the lower limb image.

[0010] Optionally, determining whether the lower limb force line has problems including varus deformity and valgus deformity based on the center point of the hip joint, the center point of the knee joint, the center point of the ankle joint, and the pressure center point on the lower limb image specifically includes: determining whether the lower limb force line has problems including varus deformity and valgus deformity based on the distance between the actual force line and the center point of the knee joint and the center point of the ankle joint, or calculating the angle between the line connecting the center point of the hip joint and the center point of the knee joint and the line connecting the center point of the knee joint and the pressure center point on the lower limb image, and calculating the angle between the line connecting the center point of the hip joint and the center point of the ankle joint and the line connecting the center point of the ankle joint and the pressure center point on the lower limb image.

[0011] Optionally, calculating the standing pressure center point based on the measurement marker point includes: establishing a Cartesian coordinate system on the plane where the measurement marker point is located; obtaining the coordinates (Xi, Yi) of the measurement marker point in the Cartesian coordinate system; calculating the standing pressure center point (Xzmp, Yzmp) based on the coordinates (Xi, Yi); the standing pressure center point (Xzmp, Yzmp) satisfies the formula: Where fi is the pressure value measured at the i-th measurement marker.

[0012] Optionally, the step of calculating the pressure center point of the standing person on the lower limb image based on the distribution of the pressure center point of the standing person and the measurement marker points includes: the lower limb image includes the captured measurement marker points, and the captured measurement marker points are in the three-dimensional coordinate system;

[0013] Based on the relationship between the distances between the measurement markers of the pressure measuring device and the distances between the photographed measurement markers, the transformation matrix K from the Cartesian coordinate system to the three-dimensional coordinate system is obtained;

[0014] The pressure center points (Xr, Yr, Zr) on the lower limb image satisfy the formula:

[0015] (Xr, Yr, Zr)=K(Xzmp, Yzmp, 0).

[0016] Secondly, embodiments of the present invention provide a system for constructing three-dimensional realistic force lines, based on a pressure measuring device and a stereoscopic image capturing device. The pressure measuring device is provided with i measuring marker points, which are sequentially connected to form a pressure measuring area, where i is greater than or equal to 3. The system includes: a marker structure for optical positioning pre-fixed on the lower limbs of a human body; an image capturing module that controls the stereoscopic image capturing device to capture images of the lower limbs of a human body walking or standing on the pressure measuring area, the lower limb images including the marker structure and the image of the pressure measuring device; a calculation module that calculates the center point of the hip joint based on the marker structure on the lower limb image; the calculation module that also calculates the standing pressure center point based on the measuring marker points; the calculation module that further calculates the pressure center point of the standing pressure center point on the lower limb image based on the distribution of the standing pressure center point and the measuring marker points; and a construction module that connects the center point of the hip joint and the pressure center point on the lower limb image to obtain realistic force lines.

[0017] The beneficial effects of the three-dimensional realistic force line construction system provided by this invention are as follows: Based on the combination of pressure measurement equipment and stereoscopic image acquisition equipment, the system acquires lower limb images of a human walking or standing on a pressure measurement area using the stereoscopic image acquisition equipment. Based on the marked structures on the lower limb images, the center point of the hip joint is calculated. Based on the measured marker points, the standing pressure center point is calculated. Based on the distribution of the standing pressure center point and the measured marker points, the pressure center point of the standing pressure center point on the lower limb image is calculated. Then, the center point of the hip joint and the pressure center point on the lower limb image are connected to obtain the realistic force line. This system can accurately evaluate the force deviation on the medial and lateral sides and the anterior and posterior sides of the knee and ankle joints, thereby providing more accurate guidance for force line correction and ensuring better surgical results.

[0018] Optionally, the pre-fixed marker structure for optical positioning on the human lower limb includes: fixing the marker structure to the femur; the calculation module is used to calculate the center point of the hip joint based on the marker structure on the lower limb image, including: obtaining the position coordinates (x, y) of the marker structure fixed to the distal end of the femur in different posture states. i y i , z i The position coordinates are in the three-dimensional coordinate system captured by the stereoscopic image capturing device; the position coordinates (a, b, c) of the center point of the hip joint satisfy the formula:

[0019] (x i -a) 2 +(y i -b) 2 +(z i -c)2 =r 2 ;

[0020] The coordinates (a, b, c) of the center point of the hip joint were calculated by fitting the center of the sphere using the least squares method.

[0021] Optionally, when the stereoscopic image capturing device acquires images of the lower limbs of a person standing on the pressure measurement area, it includes: using a probe tool with an optical positioning structure to obtain the medial and lateral points of the knee joint and the medial and lateral points of the ankle joint; the calculation module calculates the center point of the knee joint and the center point of the ankle joint based on the medial and lateral points of the knee joint and the medial and lateral points of the ankle joint; the construction module, after obtaining the true force line, includes: determining whether the lower limb force line has problems including varus deformity and valgus deformity based on the center point of the hip joint, the center point of the knee joint, the center point of the ankle joint and the pressure center point on the lower limb image.

[0022] Optionally, determining whether the lower limb force line has problems including varus deformity and valgus deformity based on the center point of the hip joint, the center point of the knee joint, the center point of the ankle joint, and the pressure center point on the lower limb image specifically includes: determining whether the lower limb force line has problems including varus deformity and valgus deformity based on the distance between the actual force line and the center point of the knee joint and the center point of the ankle joint, or calculating the angle between the line connecting the center point of the hip joint and the center point of the knee joint and the line connecting the center point of the knee joint and the pressure center point on the lower limb image, and calculating the angle between the line connecting the center point of the hip joint and the center point of the ankle joint and the line connecting the center point of the ankle joint and the pressure center point on the lower limb image.

[0023] Optionally, the calculation module calculates the standing pressure center point based on the measurement marker point, specifically including: establishing a Cartesian coordinate system on the plane where the measurement marker point is located; obtaining the coordinates (Xi, Yi) of the measurement marker point in the Cartesian coordinate system; calculating the standing pressure center point (Xzmp, Yzmp) based on the coordinates (Xi, Yi); the standing pressure center point (Xzmp, Yzmp) satisfies the formula: Where fi is the pressure value measured at the i-th measurement marker.

[0024] Optionally, the calculation module calculates the pressure center point of the standing pressure center point on the lower limb image based on the distribution of the standing pressure center point and the measurement marker points. Specifically, this includes: the lower limb image includes captured measurement marker points, which are located in the three-dimensional coordinate system; based on the distance between the measurement marker points of the pressure measuring device and the distance between the captured measurement marker points, a transformation matrix K is obtained to convert the Cartesian coordinate system to the three-dimensional coordinate system; the pressure center point (Xr, Yr, Zr) on the lower limb image satisfies the formula: (Xr, Yr, Zr) = K(Xzmp, Yzmp, 0). Attached Figure Description

[0025] Figure 1 A flowchart illustrating the method for constructing three-dimensional real force lines according to an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of a scene when obtaining three-dimensional real force lines according to an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of various joint points in the embodiments provided by the present invention;

[0028] Figure 4 This is a schematic diagram of a three-dimensional real force line construction system provided by an embodiment of the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art. The terms "comprising" and similar expressions used herein mean that the element or object preceding the word covers the element or object listed following the word and its equivalents, but do not exclude other elements or objects.

[0030] To address the problems existing in the prior art, embodiments of the present invention provide a method for constructing three-dimensional realistic force lines, with reference to... Figure 1 and Figure 2 As shown, this method is based on a pressure measuring device 2 and a stereoscopic image capturing device 1. The pressure measuring device 2 has i measurement markers, which are sequentially connected to form a pressure measuring area, where i is greater than or equal to 3. The method includes:

[0031] S101: A marker structure for optical positioning that is fixed on the lower limbs of the human body.

[0032] Specifically, the marker structure 5 is fixed to the femur.

[0033] S102: The stereoscopic imaging device acquires images of the lower limbs of a human body walking or standing on the pressure measurement area, the lower limb images including the image of the marker structure and the image of the pressure measurement device.

[0034] In this step, when the human body stands on the pressure measurement area, a probe tool 4 with an optical positioning structure is used to obtain the medial and lateral points of the knee joint and the ankle joint. The data calculation device 3 calculates the center point of the knee joint and the center point of the ankle joint based on the medial and lateral points of the knee joint and the ankle joint.

[0035] S103: Calculate the center point of the hip joint based on the marked structure on the lower limb image.

[0036] In this step, the position coordinates (x, y) of the marker structure 5 fixed to the distal femur in different posture states are obtained from the lower limb image. i y i , z i It should be noted that the position coordinates (x) i y i , z i In the three-dimensional coordinate system captured by the stereoscopic image capturing device, the coordinates (a, b, c) of the center point of the hip joint satisfy the formula: (x i -a) 2 +(y i -b) 2 +(z i -c) 2 =r 2 The coordinates (a, b, c) of the center point of the hip joint were calculated by fitting the center of the sphere using the least squares method.

[0037] S104: Calculate the standing pressure center point based on the measured marker points.

[0038] Specifically, a Cartesian coordinate system is established on the plane where the measurement marker is located, and then the coordinates (Xi, Yi) of the measurement marker in the Cartesian coordinate system are obtained. Next, the standing center of pressure (Xzmp, Yzmp) is calculated based on the coordinates (Xi, Yi). The standing center of pressure (Xzmp, Yzmp) satisfies the following formula: Additionally, fi is the pressure value measured at the i-th measurement marker.

[0039] S105: Based on the distribution of the standing pressure center point and the measurement marker point, calculate the pressure center point of the standing pressure center point on the lower limb image.

[0040] Specifically, the lower limb image includes captured measurement markers, which are located in the three-dimensional coordinate system. Based on the relationship between the distances between the measurement markers of the pressure measuring device 2 and the distances between the captured measurement markers, a transformation matrix K is obtained from the Cartesian coordinate system to the three-dimensional coordinate system.

[0041] The pressure center points (Xr, Yr, Zr) on the lower limb image satisfy the formula: (Xr, Yr, Zr) = K(Xzmp, Yzmp, 0).

[0042] S106: Connect the center point of the hip joint with the pressure center point on the lower limb image to obtain the true force line.

[0043] In this step, after obtaining the true force line, the distance between the true force line and the center point of the knee joint and the center point of the ankle joint, or the angle between the line connecting the center point of the hip joint and the center point of the knee joint and the line connecting the center point of the knee joint and the pressure center point on the lower limb image, and the angle between the line connecting the center point of the hip joint and the center point of the ankle joint and the line connecting the center point of the ankle joint and the pressure center point on the lower limb image, are used to determine whether the lower limb force line has problems including varus deformity and valgus deformity.

[0044] For details, please refer to Figure 3 As shown, in the calculation of force line parameters, let the hip center be A, the ankle center be B, the medial point of the knee joint be C, and the lateral point of the knee joint be D;

[0045] O is the intersection of line AB and line CD;

[0046] EF is the femoral mechanical axis, and TB is the tibial mechanical axis;

[0047] EF' is the projection vector of the femoral mechanical axis in the sagittal plane, and TB' is the projection vector of the tibial mechanical axis in the sagittal plane;

[0048] NV is the normal vector of the sagittal plane;

[0049] Calculate the ratio of the distance from the medial point of the knee joint to the intersection point O to the length of the medial and lateral sides of the knee joint: scale = |OC| / |CD|;

[0050] The varus / valgus angle is calculated using the angle between the tibial mechanical axis TB and the sagittal plane normal vector NV.

[0051] Abd=acos(NV.dot(TB) / (NV.norm()*TB.norm()))*180 / PI;

[0052] Flexion-extension angle, sagittal plane angle between the mechanical axes of the femur and tibia:

[0053] FE=acos(EF'.dot(TB') / (EF'.norm()*TB'.norm()))*180 / PI.

[0054] In this embodiment, based on the combination of pressure measurement equipment and stereoscopic imaging equipment, the stereoscopic imaging equipment acquires images of the lower limbs when the human body is walking or standing on the pressure measurement area. According to the marked structure on the lower limb images, the center point of the hip joint is calculated. According to the measurement marker points, the standing pressure center point is calculated. According to the distribution of the standing pressure center point and the measurement marker points, the pressure center point of the standing pressure center point on the lower limb images is calculated. Then, the center point of the hip joint and the pressure center point on the lower limb images are connected to obtain the true force line. This can accurately evaluate the force deviation on the medial and lateral and anterior and posterior sides of the knee and ankle joints, thereby more accurately guiding the correction of the force line and ensuring better surgical results.

[0055] In another embodiment of the present invention, a system for constructing three-dimensional realistic force lines is provided, based on a pressure measuring device and a stereoscopic image capturing device. The pressure measuring device has i measurement markers, which are sequentially connected to form a pressure measuring area, where i is greater than or equal to 3. (See reference) Figure 4 As shown, the system includes: a marker structure pre-fixed on the lower limbs for optical positioning; an imaging module 401, which controls the stereoscopic imaging device to acquire images of the lower limbs when the human body is walking or standing on the pressure measurement area, the lower limb images including the marker structure and the image of the pressure measurement device; a calculation module 402, used to calculate the center point of the hip joint based on the marker structure on the lower limb images; the calculation module 402 is also used to calculate the standing pressure center point based on the measurement marker points, and to calculate the pressure center point of the standing pressure center point on the lower limb images based on the distribution of the standing pressure center point and the measurement marker points; and a construction module 403, used to connect the center point of the hip joint and the pressure center point on the lower limb images to obtain a true force line.

[0056] In this embodiment, lower limb images of a human walking or standing on the pressure measurement area are acquired using a stereoscopic imaging device. Based on the marked structures on the lower limb images, the center point of the hip joint is calculated. Based on the measurement markers, the standing pressure center point is calculated. Based on the distribution of the standing pressure center point and the measurement markers, the pressure center point on the lower limb image is calculated. Then, the center point of the hip joint and the pressure center point on the lower limb image are connected to obtain the true force line. This allows for accurate evaluation of the force deviation on the medial and lateral, and anterior and posterior sides of the knee and ankle joints, thus providing more accurate guidance for force line correction and ensuring better surgical outcomes.

[0057] It should be noted that, in this embodiment, the stereoscopic image capturing device is a binocular infrared camera, and the pressure measuring device is a pressure plate.

[0058] Optionally, the pre-fixed marker structure for optical positioning on the lower limb includes: fixing the marker structure to the femur. The calculation module 402 is used to calculate the center point of the hip joint based on the marker structure on the lower limb image, including: obtaining the position coordinates (x, y) of the marker structure fixed to the distal end of the femur in different posture states. i y i , z i The position coordinates are in the three-dimensional coordinate system captured by the stereoscopic image capturing device. The position coordinates (a, b, c) of the center point of the hip joint satisfy the formula: (x i -a) 2 +(y i -b) 2 +(z i -c) 2 =r 2 The coordinates (a, b, c) of the center point of the hip joint were calculated by fitting the center of the sphere using the least squares method.

[0059] Furthermore, when the stereoscopic image capturing device acquires images of the lower limbs of a person standing on the pressure measurement area, it includes: using a probe tool with an optical positioning structure to obtain the inner and outer points of the knee joint and the inner and outer points of the ankle joint; the calculation module 402 calculates the center point of the knee joint and the center point of the ankle joint based on the inner and outer points of the knee joint and the inner and outer points of the ankle joint.

[0060] Optionally, based on the center point of the hip joint, the center point of the knee joint, the center point of the ankle joint, and the pressure center point on the lower limb image, it can be determined whether there are problems such as varus deformity and valgus deformity in the lower limb force line.

[0061] Specifically, based on the distance between the actual force line and the center point of the knee joint and the center point of the ankle joint, or by calculating the angle between the line connecting the center point of the hip joint and the center point of the knee joint and the line connecting the center point of the knee joint and the pressure center point on the lower limb image, and by calculating the angle between the line connecting the center point of the hip joint and the center point of the ankle joint and the line connecting the center point of the ankle joint and the pressure center point on the lower limb image, it is determined whether the lower limb force line has problems including varus deformity and valgus deformity.

[0062] Optionally, the calculation module 402 calculates the standing pressure center point based on the measurement marker point, specifically including: establishing a Cartesian coordinate system on the plane where the measurement marker point is located; obtaining the coordinates (Xi, Yi) of the measurement marker point in the Cartesian coordinate system; calculating the standing pressure center point (Xzmp, Yzmp) based on the coordinates (Xi, Yi); the standing pressure center point (Xzmp, Yzmp) satisfies the formula: Where fi is the pressure value measured at the i-th measurement marker.

[0063] Furthermore, the calculation module 402 calculates the pressure center point of the standing person on the lower limb image based on the distribution of the pressure center point and the measurement marker points. Specifically, this includes: the lower limb image includes captured measurement marker points, which are located in the three-dimensional coordinate system. Based on the distance relationship between the measurement marker points of the pressure measuring device and the distances between the captured measurement marker points, the transformation matrix K from the Cartesian coordinate system to the three-dimensional coordinate system is obtained. The pressure center point (Xr, Yr, Zr) on the lower limb image satisfies the formula: (Xr, Yr, Zr) = K(Xzmp, Yzmp, 0).

[0064] The above description is merely a specific implementation of the embodiments of this application, but the protection scope of the embodiments of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the embodiments of this application should be covered within the protection scope of the embodiments of this application. Therefore, the protection scope of the embodiments of this application should be determined by the protection scope of the claims.

Claims

1. A method for constructing three-dimensional realistic force lines, characterized in that, Based on a pressure measuring device and a stereoscopic image capturing device, wherein the pressure measuring device is provided with i measuring markers, and the measuring markers of the pressure measuring device are sequentially connected to form a pressure measuring area, where i is greater than or equal to 3, the method includes: A marker structure for optical positioning is fixed on the lower limbs of the human body; The stereoscopic imaging device captures images of the lower limbs of a human body walking or standing on the pressure measurement area. The lower limb images include the images of the marker structure and the pressure measurement device. The center point of the hip joint is calculated based on the marked structure on the lower limb image; The center point of pressure for standing is calculated based on the measured marker points. Based on the distribution of the standing pressure center point and the measurement marker points, the pressure center point of the standing pressure center point on the lower limb image is calculated; Connect the center point of the hip joint with the center point of pressure on the lower limb image to obtain the true force line.

2. The construction method according to claim 1, characterized in that, The marker structure fixed on the lower limb of the human body for optical positioning includes: The marker structure is fixed to the femur; The step of calculating the center point of the hip joint based on the femoral marker structure on the lower limb image includes: Obtain the position coordinates (x, y) of the marker structure fixed to the distal femur under different posture states. i y i , z i The position coordinates are in the three-dimensional coordinate system captured by the stereoscopic image capturing device; The coordinates (a, b, c) of the center point of the hip joint satisfy the formula: (x i -a) 2 +(y i -b) 2 +(z i -c) 2 =r 2 ; The coordinates (a, b, c) of the center point of the hip joint were calculated by fitting the center of the sphere using the least squares method.

3. The construction method according to claim 2, characterized in that, When the stereoscopic image capturing device acquires images of the lower limbs of a human standing on the pressure measurement area, it includes: The medial and lateral points of the knee joint and the medial and lateral points of the ankle joint are obtained using a probe tool with an optical positioning structure. The center point of the knee joint and the center point of the ankle joint are calculated based on the medial and lateral points of the knee joint and the medial and lateral points of the ankle joint. After obtaining the actual force lines, the process includes: Based on the center point of the hip joint, the center point of the knee joint, the center point of the ankle joint, and the pressure center point on the lower limb image, determine whether there are problems such as varus deformity and valgus deformity in the lower limb force line.

4. The construction method according to claim 3, characterized in that, The step of determining whether the lower limb force line has problems including varus deformity and valgus deformity based on the center point of the hip joint, the center point of the knee joint, the center point of the ankle joint, and the pressure center point on the lower limb image specifically includes: Based on the distance between the true force line and the center point of the knee joint and the center point of the ankle joint, or by calculating the angle between the center point of the hip joint and the line connecting the center point of the knee joint and the line connecting the center point of the knee joint and the pressure center point on the lower limb image, and by calculating the angle between the line connecting the center point of the hip joint and the center point of the ankle joint and the line connecting the center point of the ankle joint and the pressure center point on the lower limb image, it is determined whether the lower limb force line has problems including varus deformity and valgus deformity.

5. The construction method according to claim 2, characterized in that, The step of calculating the standing pressure center point based on the measured marker points includes: Establish a Cartesian coordinate system on the plane where the measurement markers are located; Obtain the coordinates (Xi, Yi) of the measurement marker point in the Cartesian coordinate system; The pressure center point (Xzmp, Yzmp) of the standing position is calculated based on the coordinates (Xi, Yi); the pressure center point (Xzmp, Yzmp) of the standing position satisfies the formula: Where fi is the pressure value measured at the i-th measurement marker.

6. The construction method according to claim 5, characterized in that, The step of calculating the pressure center point of the standing person on the lower limb image based on the distribution of the pressure center point of the standing person and the measurement marker points includes: The lower limb image includes captured measurement markers, which are located in the three-dimensional coordinate system. Based on the relationship between the distances between the measurement markers of the pressure measuring device and the distances between the photographed measurement markers, the transformation matrix K from the Cartesian coordinate system to the three-dimensional coordinate system is obtained; The pressure center points (Xr, Yr, Zr) on the lower limb image satisfy the formula: (Xr, Yr, Zr)=K(Xzmp, Yzmp, 0).

7. A system for constructing three-dimensional realistic force lines, characterized in that, Based on a pressure measuring device and a stereo imaging device, the pressure measuring device is provided with i measuring markers, and the measuring markers of the pressure measuring device are connected sequentially to form a pressure measuring area, where i is greater than or equal to 3. The system includes: Pre-fixed marking structures for optical positioning on the lower limbs of the human body; The imaging module controls the stereo imaging device to capture images of the lower limbs of a human body walking or standing on the pressure measurement area. The lower limb images include the image of the marker structure and the image of the pressure measurement device. The calculation module is used to calculate the center point of the hip joint based on the marked structure on the lower limb image; The calculation module is also used to calculate the standing pressure center point based on the measurement marker points; The calculation module is also used to calculate the pressure center point of the standing pressure center point on the lower limb image based on the distribution of the standing pressure center point and the measurement marker point; A construction module is used to connect the center point of the hip joint and the pressure center point on the lower limb image to obtain the true force line.

8. The construction system according to claim 7, characterized in that, The marker structure pre-fixed on the lower limb for optical positioning includes: The marker structure is fixed to the femur; The calculation module is used to calculate the center point of the hip joint based on the marked structures on the lower limb image, including: Obtain the position coordinates (x, y) of the marker structure fixed to the distal femur under different posture states. i y i , z i The position coordinates are in the three-dimensional coordinate system captured by the stereoscopic image capturing device; The coordinates (a, b, c) of the center point of the hip joint satisfy the formula: (x i -a) 2 +(y i -b) 2 +(z i -c) 2 =r 2 ; The coordinates (a, b, c) of the center point of the hip joint were calculated by fitting the center of the sphere using the least squares method.

9. The construction system according to claim 8, characterized in that, When the stereoscopic image capturing device acquires images of the lower limbs of a human standing on the pressure measurement area, it includes: The medial and lateral points of the knee joint and the medial and lateral points of the ankle joint are obtained using a probe tool with an optical positioning structure. The calculation module calculates the center point of the knee joint and the center point of the ankle joint based on the medial and lateral points of the knee joint and the medial and lateral points of the ankle joint. The construction module, after obtaining the actual force lines, includes: Based on the center point of the hip joint, the center point of the knee joint, the center point of the ankle joint, and the pressure center point on the lower limb image, determine whether there are problems such as varus deformity and valgus deformity in the lower limb force line.

10. The construction system according to claim 9, characterized in that, The step of determining whether the lower limb force line has problems including varus deformity and valgus deformity based on the center point of the hip joint, the center point of the knee joint, the center point of the ankle joint, and the pressure center point on the lower limb image specifically includes: Based on the distance between the true force line and the center point of the knee joint and the center point of the ankle joint, or by calculating the angle between the center point of the hip joint and the line connecting the center point of the knee joint and the line connecting the center point of the knee joint and the pressure center point on the lower limb image, and by calculating the angle between the line connecting the center point of the hip joint and the center point of the ankle joint and the line connecting the center point of the ankle joint and the pressure center point on the lower limb image, it is determined whether the lower limb force line has problems including varus deformity and valgus deformity.

11. The construction system according to claim 8, characterized in that, The calculation module calculates the standing pressure center point based on the measurement markers, specifically including: Establish a Cartesian coordinate system on the plane where the measurement markers are located; Obtain the coordinates (Xi, Yi) of the measurement marker point in the Cartesian coordinate system; The pressure center point (Xzmp, Yzmp) of the standing position is calculated based on the coordinates (Xi, Yi); the pressure center point (Xzmp, Yzmp) of the standing position satisfies the formula: Where fi is the pressure value measured at the i-th measurement marker.

12. The construction system according to claim 11, characterized in that, The calculation module calculates the pressure center point of the standing person on the lower limb image based on the distribution of the pressure center point and the measurement marker points, specifically including: The lower limb image includes captured measurement markers, which are located in the three-dimensional coordinate system. Based on the relationship between the distances between the measurement markers of the pressure measuring device and the distances between the photographed measurement markers, the transformation matrix K from the Cartesian coordinate system to the three-dimensional coordinate system is obtained; The pressure center points (Xr, Yr, Zr) on the lower limb image satisfy the formula: (Xr, Yr, Zr)=K(Xzmp, Yzmp, 0).

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