Registration method for spatial points of medical assistant robotic arm

Abstract

A registration method for spatial points of a medical assistant robotic arm. On the basis of an infrared mark, accurate registration of different device spatial points is achieved by means of rotary registration. The method comprises: for a medical assistant robotic arm device, fixing an infrared mark to the tail end of a robotic arm; rotating a tail-end shaft under the condition of two different poses at the same position; using an infrared camera to record the position of the infrared mark, respectively fitting circles, and calculating the axes on which the centers of the circles are located; and finally, determining the intersection point of the two axes, and registering same as a tool center point of the robotic arm. The method is simply and easily operated, acheives high precision, and significantly improves the registration accuracy and reliability of spatial points of medical devices.

Description

A registration method for spatial points of medical assistive robotic arms Technical Field

[0001] The present invention relates to the technical field of medical equipment registration, and in particular to a method for registering spatial points of a medical assistive robotic arm. Background Art

[0002] With the development of science and technology and the widespread application of medical-assisted robotic arms in clinical treatment, the spatial position registration accuracy of medical equipment such as medical robotic arms is also in urgent need of improvement.

[0003] Traditional robotic arm registration methods involve moving the robotic arm to different positions in space, obtaining the positions in the robotic arm coordinate system and the field coordinate system, and then solving a transformation matrix to determine the mutual conversion relationship between the robotic arm coordinate system and the field coordinate system. However, the accuracy of this method is significantly affected by the accuracy of the robotic arm and the infrared camera, and it also lacks robustness. Besides these methods, a commonly used improvement involves fixing specific workpieces to the robotic arm, moving the robotic arm to different spatial positions, obtaining the positions in the robotic arm coordinate system and the field coordinate system, and finally solving a transformation matrix to determine the mutual conversion relationship between the robotic arm coordinate system and the field coordinate system. However, this method is affected by factors such as the workpiece machining accuracy and the workpiece fixing method, making it not only complex but also lacking in robustness. Summary of the Invention

[0004] In view of the shortcomings of the above methods, the purpose of this method is to propose a registration method for spatial points of medical assistive robotic arms, aiming to improve the registration accuracy of medical equipment using a simple method.

[0005] The technical solution adopted by the method of the present invention is:

[0006] The present invention provides a method for registering spatial points of a medical assistive robotic arm, which can use an infrared marker to register spatial points of a medical assistive robotic arm device. The specific steps are as follows:

[0007] First, fix an infrared marker at any position on the end of the robotic arm.

[0008] Next, the robotic arm is moved to any position in space, the last axis of the robotic arm is rotated, and the spatial position of the infrared marker is tracked in real time through the infrared camera.

[0009] The collected infrared marker position point set A i Fitting a plane circle in three-dimensional space And calculate the axis through the center of the circle

[0010] Keep the spatial position of the end of the robotic arm unchanged and solve another posture at this spatial position.

[0011] The robotic arm is changed to a second posture at the same spatial position, the last axis of the robotic arm is rotated, and the spatial position of the infrared marker is tracked in real time by an infrared camera.

[0012] The collected infrared marker location point set B i Fitting a plane circle in three-dimensional space And calculate the axis through the center of the circle

[0013] Solve and The intersection point or the midpoint of the line connecting the two axes is denoted as P i , which is the position of the center point of the robot tool at this position, and the three-dimensional spatial position R of the robot is recorded at the same time i .

[0014] Finally, repeat the above steps to record no less than 3 groups of point sets {P i ,R i}, i=1,2,3…, the transformation matrix between the camera coordinate system and the robotic arm coordinate system can be further solved

[0015] Among them, for the robotic arm in the method, its last joint is the rotation axis. When the last axis rotates, only the posture of the robotic arm changes, and the position does not change; the rotation axis of the last joint passes through the origin of the end of the robotic arm.

[0016] In addition, when the last joint of the robotic arm rotates, the infrared marker also changes.

[0017] In addition, it should be noted that, first, when the infrared camera tracks the infrared marker in real time, the robotic arm should rotate at least 90°.

[0018] Secondly, when solving the second posture, the angle between the two postures should be greater than 30°.

[0019] In addition, when solving the intersection point of the line connecting two axes, if the two axes do not intersect, the midpoint should be taken as the midpoint of the intersection of the two axes and their common perpendicular line.

[0020] Also, the three-dimensional spatial position R of the recorded robotic arm i is the three-dimensional coordinate in the robot arm coordinate system.

[0021] Finally, the midpoint P of the line connecting the two axes is calculated i is the three-dimensional coordinate in the camera coordinate system.

[0022] The above method can also be applied to medical equipment containing robotic arm structures such as linear accelerators

[0023] The present invention improves the accuracy of medical device spatial point registration and reduces the dependence on registration artifacts, thus overcoming the shortcomings of existing registration methods. In addition, the present invention has the following significant advantages:

[0024] (1) The method of the present invention only utilizes one infrared marker, which reduces the cost of spatial point registration of medical assistive robotic arm equipment.

[0025] (2) The method of the present invention utilizes the rotation of the medical device and the real-time tracking of the infrared camera. While registering the spatial points, it can also simultaneously verify whether the accuracy of the medical device and the infrared camera meets the clinical requirements.

[0026] (3) The method of the present invention improves the robustness of registration accuracy by rotating the points in the registration space.

[0027] (4) The registration method proposed by the present invention is simple and does not require excessive training for operators. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a flow chart of spatial point registration for medical assistive robotic arm equipment;

[0029] FIG2 is a schematic diagram of solving the intersection point of the rotation axes when two axes intersect;

[0030] FIG3 is a schematic diagram of solving the midpoint of the intersection of two axes and their common perpendicular line when the two axes do not intersect. DETAILED DESCRIPTION

[0031] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] 1 , before surgery, the process of using the present invention to register the center point of a domestically produced seven-axis medical assistive robotic arm tool is as follows:

[0033] Step 1: Attach an infrared marker to the edge of the end of the seven-axis robotic arm so that when the seven-axis robotic arm rotates the seventh rotary joint, the infrared marker can rotate with the robotic arm.

[0034] Step 2: Send commands to the robotic arm, causing its joint angles to adjust to the following: 73.714°, -27.930°, 0.000°, 34.631°, -57.295°, -54.745°, and -180.000°. Once the robotic arm reaches its initial position, send commands to move it to its target position: 73.714°, -27.930°, 0.000°, 34.631°, -57.295°, -54.745°, and 180.000°, rotating the seventh axis from -180° to 180°. During this rotation, use a binocular infrared camera to capture the spatial coordinates of the infrared markers in real time, obtaining point set A1 at the initial position.

[0035] Step 3: Use the least squares method to fit the plane circle through the point set A1 And calculated the axis passing through the center of the circle

[0036] Step 4: Calculate another posture of the robotic arm at this position: 57.425°, -45.363°, 0.000°, 49.446°, -74.419°, -23.943°, -180.000°.

[0037] Step 5: First, use instructions to move it to the initial position of posture 2, and then send instructions to make the robot arm reach the target position 57.425°, -45.363°, 0.000°, 49.446°, -74.419°, -23.943°, 180.000°, that is, rotate the seventh axis from -180° to 180°.

[0038] Step 6: While rotating, let the binocular infrared camera capture the spatial coordinates of the infrared marker in real time to obtain the point set B1 of the initial position. Using the point set B1, the plane circle is fitted using the least squares method. And calculated the axis passing through the center of the circle

[0039] Step 7: According to and Calculate the intersection of the common perpendicular line of the two axes and the two axes, and calculate the midpoint P of the intersection 1 =(192.09,528.90,-1620.36), which is the position of the tool center of the robot arm in the current state. At the same time, the position of the robot arm R is recorded. 1 It is (-167.07, -130.81, 975.35).

[0040] Step 8: We obtain four more point sets {P 2 ,R 2}, {P 3 ,R 3}, {P4 ,R 4}, and calculate the transformation matrix for:

[0041] The above disclosure is merely a preferred embodiment of the present invention and certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A registration method for spatial points of a medical assistive robot arm, characterized in that: An infrared marker can be used to register the spatial points of the medical assistive robotic arm device. The specific steps are as follows: S01: Fix an infrared marker at any position on the end of the robotic arm. S02: Move the robotic arm to any position in space, rotate the last axis of the robotic arm, and track the spatial position of the infrared marker in real time through the infrared camera. S03: Collect the infrared marked position point set A i Fitting a plane circle in three-dimensional space And calculate the axis through the center of the circle S04: Keep the spatial position of the end of the robot arm unchanged, and solve another posture under the spatial position. S05: Change the robotic arm to a second posture at the same spatial position, rotate the last axis of the robotic arm, and simultaneously track the spatial position of the infrared marker in real time through the infrared camera. S06: Collect the infrared marked position point set B i Fitting a plane circle in three-dimensional space And calculate the axis through the center of the circle S07: Solve and The intersection point or the midpoint of the line connecting the two axes is denoted as P i , which is the position of the center point of the robot tool at this position, and the three-dimensional spatial position R of the robot is recorded at the same time i . S08: Repeat the above steps to record no less than 3 groups of point sets {P i ,R i }, i = 1, 2, 3…, the transformation matrix between the camera coordinate system and the robot arm coordinate system can be further solved 2. A registration method for a medical assistive robot arm space point according to claim 1, characterized in that: The last joint of the robotic arm is a rotation axis. When the last axis rotates, only the posture of the robotic arm changes, and the position does not change. The rotation axis of the last joint passes through the origin of the end of the robotic arm.

3. A registration method for spatial points of a medical assistive robot arm according to claim 1, characterized in that: When the last joint of the robotic arm rotates, the infrared marker also changes.

4. A method for registering spatial points of a medical assistive robot arm according to claim 1, characterized in that: When the infrared camera tracks the infrared marker in real time, the robotic arm should rotate at least 90°.

5. A method for registering spatial points of a medical assistive robot arm according to claim 1, characterized in that: When solving the second posture, the angle between the two postures should be greater than 30°.

6. A method for registering spatial points of a medical assistive robot arm according to claim 1, characterized in that: When solving the intersection point of the line connecting two axes, if the two axes do not intersect, the midpoint should be taken as the midpoint of the intersection of the two axes and their common perpendicular line.

7. A method for registering spatial points of a medical assistive robot arm according to claim 1, characterized in that: The three-dimensional spatial position R of the recorded robotic arm i is the three-dimensional coordinate in the robot coordinate system.

8. A method for registering spatial points of a medical assistive robot arm according to claim 1, characterized in that: The midpoint P of the calculated two-axis line i is the three-dimensional coordinate in the camera coordinate system.

9. A method for registering spatial points of a medical assistive robot arm according to claim 1, characterized in that: The method can also be applied to medical equipment including a robotic arm structure, such as a linear accelerator.

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