Mechanical arm coordinate conversion calibration method and device based on optical tracking system

Abstract

The invention relates to a mechanical arm coordinate conversion calibration method and device based on an optical tracking system, and the method comprises the steps: installing the optical tracking system, and fixing an optical calibration plate on a base of a to-be-calibrated mechanical arm; adjusting the joint of the mechanical arm to be calibrated to a standard zero position; sampling sample points in a plurality of directions perpendicular to the base flange plate through an infrared optical probe; performing circle center calculation based on a space circle equation, and determining a coordinate axis of the base; determining an intersection point on a base shaft and a base center point of the mechanical arm; calculating a space coordinate transformation matrix of the base according to the center point of the base and the X axis and the Y axis of the base; and the conversion module is used for converting the mechanical arm base into a coordinate system of the optical tracking system in real time based on the position of the optical calibration plate. Compared with the prior art, the problems that in a traditional method, operation is complex, the calculated amount is large, and the environmental influence is large are effectively solved, the positioning workload of the mechanical arm is remarkably simplified, and the working efficiency and operation safety of the mechanical arm are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of robot arm calibration, and in particular to a robot arm coordinate conversion calibration method and device based on an optical tracking system. Background Art

[0002] With the development of industrial automation and robotics technology, robotic arms are increasingly used in manufacturing, medical treatment, services and other fields, and the requirements for their working accuracy are also getting higher and higher. Coordinate conversion calibration is a key step to ensure the accuracy of robotic arms. However, the current common calibration method is to install the calibration object near the end effector of the robotic arm, which not only increases the load at the end of the robotic arm and affects the loading and unloading operations of the actuator, but also increases the risk of collision with the calibration object when the joint rotates, which may cause hardware damage and reduce the reliability of the system. In addition, the traditional calibration method also requires complex operations and a large amount of calculations, and is easily affected by environmental factors, resulting in low calibration accuracy. Therefore, there is an urgent need for a coordinate conversion calibration method and device that can simplify the operation and improve the calibration accuracy. Summary of the invention

[0003] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a robot arm coordinate conversion calibration method and device based on an optical tracking system that can simplify the operation and improve the calibration accuracy.

[0004] The purpose of the present invention can be achieved by the following technical solutions:

[0005] A method for calibrating coordinate transformation of a robotic arm based on an optical tracking system comprises the following steps:

[0006] An optical tracking system is installed within the working space of the robotic arm to be calibrated, and an optical calibration plate is fixed on the base of the robotic arm to be calibrated;

[0007] Adjust the joints of the robot arm to be calibrated to the standard zero position and ensure that the shoulder joint is parallel to the X-axis of the base;

[0008] At least three Z-axis sample points are continuously sampled in a preset clockwise direction in a Z-axis direction perpendicular to the base flange by an infrared optical probe; at least three X-axis sample points are sampled in a preset clockwise direction in an X-axis direction perpendicular to the base flange by an infrared optical probe; and during the sampling process of the infrared optical probe, the spatial position of the sampling point in the optical tracking system is determined by the optical tracking system;

[0009] Based on the spatial circle equation, the center of the Z point set ZC and the center of the X point set XC are calculated according to the sampled Z-axis sample points and X-axis sample points, so as to determine the directions of the X-axis, Y-axis and Z-axis of the base of the robot to be calibrated in the optical tracking system;

[0010] The intersection point CP of the straight line from the center ZC of the Z point set to the Z axis and the straight line from the center XC of the X point set to the X axis is taken as the point on the base axis;

[0011] Extend the radius unit of the robot base axis in the Z-axis direction in the opposite direction from the intersection point CP to determine the spatial point coordinate BaseCenter of the robot base center point in the optical tracking system;

[0012] According to the spatial point coordinates BaseCenter and the X-axis and Y-axis of the base, calculate the spatial coordinate transformation matrix of the base of the robot;

[0013] The spatial position of the optical calibration plate is tracked in real time by the optical tracking system, and is associated with the spatial position of the base center of the robotic arm to be calibrated, so as to calculate the spatial position of the base center of the robotic arm to be calibrated in the optical tracking system based on the spatial coordinate transformation matrix of the base.

[0014] Furthermore, the position of the light-emitting point of the optical calibration plate is adjustable so as to be within the visible range of the optical tracking system.

[0015] Furthermore, the optical calibration plate is fixed below the base of the robotic arm to be calibrated.

[0016] Furthermore, among the three Z-axis sample points, an angle between the first Z-axis sample point Z0 and the center of the base flange and an angle between the third Z-axis sample point Z2 and the center of the base flange is at least 180 degrees.

[0017] Furthermore, among the three X-axis sample points, an angle between the first X-axis sample point X0 and the center of the base flange and an angle between the third X-axis sample point X2 and the center of the base flange is at least 180 degrees.

[0018] The present invention also provides a robot arm coordinate conversion calibration device based on an optical tracking system, comprising:

[0019] An optical calibration plate, used to fix the base of the robot arm to be calibrated;

[0020] Infrared optical probe, used to collect axial feature points of the robot arm base;

[0021] An optical tracking system is used to track the spatial position of the optical calibration plate and the spatial position of the infrared optical probe sampling;

[0022] The control module is used to perform the following steps:

[0023] Adjust the joints of the robot arm to be calibrated to the standard zero position and ensure that the shoulder joint is parallel to the X-axis of the base;

[0024] At least three Z-axis sample points are continuously sampled in a preset clockwise direction in a Z-axis direction perpendicular to the base flange by an infrared optical probe; at least three X-axis sample points are sampled in a preset clockwise direction in an X-axis direction perpendicular to the base flange by an infrared optical probe; and during the sampling process of the infrared optical probe, the spatial position of the sampling point in the optical tracking system is determined by the optical tracking system;

[0025] Based on the spatial circle equation, the center of the Z point set ZC and the center of the X point set XC are calculated according to the sampled Z-axis sample points and X-axis sample points, so as to determine the directions of the X-axis, Y-axis and Z-axis of the base of the robot to be calibrated in the optical tracking system;

[0026] The intersection point CP of the straight line from the center ZC of the Z point set to the Z axis and the straight line from the center XC of the X point set to the X axis is taken as the point on the base axis;

[0027] Extend the radius unit of the robot base axis in the Z-axis direction in the opposite direction from the intersection point CP to determine the spatial point coordinate BaseCenter of the robot base center point in the optical tracking system;

[0028] According to the spatial point coordinates BaseCenter and the X-axis and Y-axis of the base, calculate the spatial coordinate transformation matrix of the base of the robot;

[0029] The spatial position of the optical calibration plate is tracked in real time by the optical tracking system, and is associated with the spatial position of the base center of the robotic arm to be calibrated, so as to calculate the spatial position of the base center of the robotic arm to be calibrated in the optical tracking system based on the spatial coordinate transformation matrix of the base.

[0030] Furthermore, the position of the light-emitting point of the optical calibration plate is adjustable so as to be within the visible range of the optical tracking system.

[0031] Furthermore, the optical calibration plate is fixed below the base of the robotic arm to be calibrated.

[0032] Furthermore, among the three Z-axis sample points, an angle between the first Z-axis sample point Z0 and the center of the base flange and an angle between the third Z-axis sample point Z2 and the center of the base flange is at least 180 degrees.

[0033] Furthermore, among the three X-axis sample points, an angle between the first X-axis sample point X0 and the center of the base flange and an angle between the third X-axis sample point X2 and the center of the base flange is at least 180 degrees.

[0034] Compared with the prior art, the robot arm coordinate conversion calibration method and device based on the optical tracking system provided by the present invention has significant advantages in simplifying the operation process, improving the calibration accuracy and enhancing the system safety through the combination of the optical tracking system and the infrared calibration probe, and solves many problems existing in the prior art, and has the following advantages:

[0035] (1) The present invention uses an infrared optical calibration probe to collect three sample points in the Z direction and the X direction respectively, and ensures that the distribution of the sample points has a sufficient angle; this design ensures the uniformity and accuracy of the collected data, reduces the calculation error caused by the uneven distribution of sample points, and further improves the calibration accuracy;

[0036] The center of the robot base is accurately located by calculating the spatial coordinates of the center point of the robot base, ensuring the accuracy of the entire calibration system;

[0037] Based on the spatial coordinates of the center of the robot base, an accurate coordinate transformation matrix of the robot base is generated, ensuring the accurate conversion from the optical tracking system to the robot base coordinate system; the present invention significantly reduces the computational complexity in this process and improves the efficiency and accuracy of calibration.

[0038] (2) The present invention reduces the end load and avoids the risk of collision by installing the optical tracking system in the working space of the robot arm and fixing the optical calibration plate at an appropriate position on the base, thereby greatly improving the operating safety of the robot arm.

[0039] (3) The present invention ensures the consistency and accuracy of the calibration process by adjusting the robot arm to the standard zero position, thereby reducing the calibration error caused by the inaccurate initial position of the robot arm in the traditional method.

[0040] (4) The function of the optical calibration plate of the present invention is to enable the binocular recognition system to monitor the position change of the optical calibration plate in real time through the fixed position relationship between the optical calibration plate and the robot arm base, thereby accurately detecting the position change of the robot arm. This design enables the motion state of the robot arm to be captured in real time and ensures high-precision positioning during the coordinate conversion process.

[0041] (5) Overall, the present invention effectively solves the problems of complex operation, large amount of calculation, and large environmental impact in traditional methods, significantly simplifies the positioning workload of the robot arm, and improves the working efficiency and operational safety of the robot arm. It is suitable for fields such as precision manufacturing, medical surgery, and robotics research. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A schematic flow chart of a method for calibrating coordinate conversion of a robot arm base based on an optical tracking system provided in an embodiment of the present invention;

[0043] Figure 2 A schematic diagram of the initial state of the position relationship between a mechanical arm and a calibration plate provided in an embodiment of the present invention, wherein the green part is the mechanical arm model;

[0044] Figure 3 A schematic diagram of collecting sample points in the X-axis direction provided in an embodiment of the present invention, wherein the red dots represent three sample points collected in the X-axis direction by the optical probe;

[0045] Figure 4 A schematic diagram of overall collection points after Z-axis direction sample collection provided in an embodiment of the present invention, wherein green dots represent three sample points collected by an optical probe in the Z-axis direction;

[0046] Figure 5 A state schematic diagram of a robot arm in an optical tracking system is provided in an embodiment of the present invention, in which the spatial coordinate position of the robot arm in the optical tracking system is calculated by utilizing a point set collected by a probe. In the figure, the green model represents the robot arm, the red, green, and blue coordinate axes in the upper middle represent the spatial coordinate position of the calibration plate in the optical tracking system, and the red, green, and blue coordinate axes in the lower middle represent the spatial coordinate position of the probe in the optical tracking system. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0048] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0050] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are the directions or positional relationships in which the inventive product is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0051] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0052] In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0053] Example 1

[0054] like Figure 1 As shown, this embodiment provides a robot arm base coordinate conversion calibration method based on an optical tracking system, comprising the following steps:

[0055] Assembly S1: Install the optical tracking system within the working space of the robot. Fix the optical calibration plate at an appropriate position below the base of the robot;

[0056] The function of the optical calibration plate is to enable the binocular recognition system to monitor the position changes of the optical calibration plate in real time through the fixed position relationship between the plate and the robot arm base, thereby accurately detecting the position changes of the robot arm. This design enables the motion state of the robot arm to be captured in real time and ensures high-precision positioning during the coordinate conversion process;

[0057] Robot arm calibration S2: Adjust the robot arm joint to the standard zero position and ensure that the shoulder joint is parallel to the base X axis. Figure 2 As shown;

[0058] Collect Z-direction sample points S3: Use an infrared optical calibration probe to continuously collect three sample points Z0, Z1, and Z2 in the Z direction perpendicular to the flange of the robot base in a counterclockwise direction. Figure 4 As shown by the green dots in;

[0059] Preferably, the angle between Z0 and the center of the flange and Z2 and the center of the flange is at least 180 degrees to ensure that the point distribution is sufficiently uniform.

[0060] Collecting sample points S4 in the X direction: Use an infrared optical calibration probe to continuously collect three sample points X0, X1, and X2 in the X direction perpendicular to the flange of the robot base in a counterclockwise direction. Figure 3 As shown by the red dots in;

[0061] Preferably, the angle between X0 and the center of the flange and X2 and the center of the flange is at least 180 degrees to ensure that the point distribution is sufficiently uniform.

[0062] Calculate the center of the circle and the coordinate axis S5: Use the spatial circle equation to take the collected sample point set Z (Z0, Z1, Z2) and the sample point set X (X0, X1, X2) as input to calculate the center ZC of the Z point set and the center XC of the X point set, thereby determining the directions of the X-axis, Y-axis, and Z-axis of the robot base in the optical tracking system.

[0063] Determine the intersection point S6 on the base axis: the intersection point CP from the center ZC of the Z point set to the Z axis and the center XC of the X point set to the X axis is the point on the base axis.

[0064] Calculate the coordinates of the center point of the base S7: Extend the radius unit of the robot base axis in the opposite direction of the spatial point CP to the Z-axis direction, and calculate the coordinates of the spatial point BaseCenter of the center point of the robot base in the optical tracking system.

[0065] Generate coordinate transformation matrix S8: The spatial coordinate transformation matrix MvsH of the robot base can be calculated through the spatial point BaseCenter and the X-axis and Y-axis of the base.

[0066] Combined transformation matrix S9: coordinate transformation matrix H returned by the optical tracker, and the space transformation matrix M from the center of the manipulator base to the optical tracking system, MvsH = H.mul(M);

[0067] like Figure 5 As shown in the figure, it is a schematic diagram of the results of determining the spatial coordinate position of the robot arm in the optical tracking system, wherein the green model represents the robot arm, the red, green, and blue coordinate axes above the figure represent the spatial coordinate position of the calibration plate in the optical tracking system, and the red, green, and blue coordinate axes below represent the spatial coordinate position of the probe in the optical tracking system.

[0068] Preferably, the position of the infrared light reflecting calibration ball of the optical calibration plate can be adjusted at will to adapt to the visual range of the optical tracker.

[0069] The optical calibration plate is fixed below the base of the robotic arm to avoid affecting the loading and unloading operations of the end effector of the robotic arm.

[0070] The above is an introduction to a method embodiment. The following is a further explanation of the present invention through an apparatus embodiment.

[0071] This embodiment provides a robot arm coordinate conversion calibration device based on an optical tracking system, comprising:

[0072] An optical calibration plate, used to fix the base of the robot arm to be calibrated;

[0073] Infrared optical probe, used to collect axial feature points of the robot arm base;

[0074] An optical tracking system is used to track the spatial position of the optical calibration plate and the spatial position of the infrared optical probe sampling;

[0075] The control module is used to perform the following steps:

[0076] Adjust the joints of the robot arm to be calibrated to the standard zero position and ensure that the shoulder joint is parallel to the X-axis of the base;

[0077] At least three Z-axis sample points are continuously sampled in a preset clockwise direction in a Z-axis direction perpendicular to the base flange by an infrared optical probe; at least three X-axis sample points are sampled in a preset clockwise direction in an X-axis direction perpendicular to the base flange by an infrared optical probe; and during the sampling process of the infrared optical probe, the spatial position of the sampling point in the optical tracking system is determined by the optical tracking system;

[0078] Based on the spatial circle equation, the center of the Z point set ZC and the center of the X point set XC are calculated according to the sampled Z-axis sample points and X-axis sample points, so as to determine the directions of the X-axis, Y-axis and Z-axis of the base of the robot to be calibrated in the optical tracking system;

[0079] The intersection point CP of the straight line from the center ZC of the Z point set to the Z axis and the straight line from the center XC of the X point set to the X axis is taken as the point on the base axis;

[0080] Extend the radius unit of the robot base axis in the Z-axis direction in the opposite direction from the intersection point CP to determine the spatial point coordinate BaseCenter of the robot base center point in the optical tracking system;

[0081] According to the spatial point coordinates BaseCenter and the X-axis and Y-axis of the base, calculate the spatial coordinate transformation matrix of the base of the robot;

[0082] The spatial position of the optical calibration plate is tracked in real time through the optical tracking system, and the spatial position of the base center of the robotic arm to be calibrated is associated with it. Therefore, based on the spatial coordinate transformation matrix of the base, the spatial position of the base center of the robotic arm to be calibrated in the optical tracking system is calculated.

[0083] It should be noted that the specific content and beneficial effects of the device of the present application can be found in the above-mentioned method embodiment, which will not be repeated here.

[0084] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A robot arm coordinate conversion calibration method based on an optical tracking system, characterized in that: The following steps are involved: An optical tracking system is installed within the working space of the robotic arm to be calibrated, and an optical calibration plate is fixed on the base of the robotic arm to be calibrated; Adjust the joints of the robot arm to be calibrated to the standard zero position and ensure that the shoulder joint is parallel to the X-axis of the base; At least three Z-axis sample points are continuously sampled in a preset clockwise direction in a Z-axis direction perpendicular to the base flange by an infrared optical probe; at least three X-axis sample points are sampled in a preset clockwise direction in an X-axis direction perpendicular to the base flange by an infrared optical probe; And during the sampling process of the infrared optical probe, the spatial position of the sampling point in the optical tracking system is determined by the optical tracking system; Based on the spatial circle equation, the center of the Z point set ZC and the center of the X point set XC are calculated according to the sampled Z-axis sample points and X-axis sample points, so as to determine the directions of the X-axis, Y-axis and Z-axis of the base of the robot to be calibrated in the optical tracking system; The intersection point CP of the straight line from the center ZC of the Z point set to the Z axis and the straight line from the center XC of the X point set to the X axis is taken as the point on the base axis; Extend the radius unit of the robot base axis in the Z-axis direction in the opposite direction from the intersection point CP to determine the spatial point coordinate BaseCenter of the robot base center point in the optical tracking system; According to the spatial point coordinates BaseCenter and the X-axis and Y-axis of the base, calculate the spatial coordinate transformation matrix of the base of the robot; The spatial position of the optical calibration plate is tracked in real time by the optical tracking system, and is associated with the spatial position of the base center of the robotic arm to be calibrated, so as to calculate the spatial position of the base center of the robotic arm to be calibrated in the optical tracking system based on the spatial coordinate transformation matrix of the base.

2. According to the method for calibration of coordinate transformation of a robot arm based on an optical tracking system according to claim 1, it is characterized in that: The position of the light-emitting point of the optical calibration plate is adjustable so as to be within the visible range of the optical tracking system.

3. The method for calibration of robot arm coordinate transformation based on optical tracking system according to claim 1, characterized in that: The optical calibration plate is fixed below the base of the mechanical arm to be calibrated.

4. The method for calibration of coordinate transformation of a robot arm based on an optical tracking system according to claim 1, characterized in that: Among the three Z-axis sample points, the angle between the first Z-axis sample point Z0 and the center of the base flange and the angle between the third Z-axis sample point Z2 and the center of the base flange is at least 180 degrees.

5. The method for calibration of robot arm coordinate transformation based on optical tracking system according to claim 1, characterized in that: Among the three X-axis sample points, the angle between the first X-axis sample point X0 and the center of the base flange and the angle between the third X-axis sample point X2 and the center of the base flange is at least 180 degrees.

6. A robot arm coordinate conversion calibration device based on an optical tracking system, characterized in that: include: An optical calibration plate, used to fix the base of the robot arm to be calibrated; Infrared optical probe, used to collect axial feature points of the robot arm base; An optical tracking system is used to track the spatial position of the optical calibration plate and the spatial position of the infrared optical probe sampling; The control module is used to perform the following steps: Adjust the joints of the robot arm to be calibrated to the standard zero position and ensure that the shoulder joint is parallel to the X-axis of the base; At least three Z-axis sample points are continuously sampled in a preset clockwise direction in a Z-axis direction perpendicular to the base flange by an infrared optical probe; at least three X-axis sample points are sampled in a preset clockwise direction in an X-axis direction perpendicular to the base flange by an infrared optical probe; And during the sampling process of the infrared optical probe, the spatial position of the sampling point in the optical tracking system is determined by the optical tracking system; Based on the spatial circle equation, the center of the Z point set ZC and the center of the X point set XC are calculated according to the sampled Z-axis sample points and X-axis sample points, so as to determine the directions of the X-axis, Y-axis and Z-axis of the base of the robot to be calibrated in the optical tracking system; The intersection point CP of the straight line from the center ZC of the Z point set to the Z axis and the straight line from the center XC of the X point set to the X axis is taken as the point on the base axis; Extend the radius unit of the robot base axis in the Z-axis direction in the opposite direction from the intersection point CP to determine the spatial point coordinate BaseCenter of the robot base center point in the optical tracking system; According to the spatial point coordinates BaseCenter and the X-axis and Y-axis of the base, calculate the spatial coordinate transformation matrix of the base of the robot; The spatial position of the optical calibration plate is tracked in real time by the optical tracking system, and is associated with the spatial position of the base center of the robotic arm to be calibrated, so as to calculate the spatial position of the base center of the robotic arm to be calibrated in the optical tracking system based on the spatial coordinate transformation matrix of the base.

7. The robot arm coordinate conversion calibration device based on an optical tracking system according to claim 6, characterized in that: The position of the light-emitting point of the optical calibration plate is adjustable so as to be within the visible range of the optical tracking system.

8. The device for converting and calibrating a robot arm coordinate based on an optical tracking system according to claim 6, characterized in that: The optical calibration plate is fixed below the base of the mechanical arm to be calibrated.

9. The robot arm coordinate conversion calibration device based on an optical tracking system according to claim 6, characterized in that: Among the three Z-axis sample points, the angle between the first Z-axis sample point Z0 and the center of the base flange and the angle between the third Z-axis sample point Z2 and the center of the base flange is at least 180 degrees.

10. The device for coordinate conversion and calibration of a robot arm based on an optical tracking system according to claim 6, characterized in that: Among the three X-axis sample points, the angle between the first X-axis sample point X0 and the center of the base flange and the angle between the third X-axis sample point X2 and the center of the base flange is at least 180 degrees.

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