Calibration tool for arm support of mechanical arm

Abstract

The invention belongs to the technical field of accessory devices matched with mechanical arms, and particularly provides a mechanical arm frame calibration tool. The calibration tool comprises a main body, the main body is of a regular N prism structure, N is larger than or equal to 3, one end of the main body is provided with a connecting structure used for being fixedly connected with the tail end of a mechanical arm frame, at least two targets are installed on each side face of the main body, a plurality of mark points are arranged on the targets, and the targets are arranged in the axis direction of the main body. In this way, when the arm support is calibrated, after the arm support rotates by a certain angle, it can be ensured that the side face can still face the optical camera located at the fixed position, at the moment, the optical camera can still obtain information of the target, and therefore the position of the tail end of the arm support of the mechanical arm is calibrated. Meanwhile, one point of each of the two targets can be selected as a mark point for calculating the pose information, and the pose information of the tail end of the arm support of the mechanical arm can be calibrated according to a simple geometrical relationship.

Description

Technical Field

[0001] The invention belongs to the technical field of accessory devices cooperating with a manipulator, and in particular relates to a manipulator arm frame calibration tool. Background Art

[0002] In the field of tunnel construction, matching related tunnel construction equipment is often used according to different construction needs. Tunnel construction equipment is generally equipped with a multi-degree-of-freedom robotic arm, and the end of the multi-degree-of-freedom robotic arm is equipped with the actuator required for construction. For example, the two-arm / three-arm rock drilling rig commonly used in drilling and blasting construction projects has a rock drilling rig for drilling blastholes installed at the end of the multi-degree-of-freedom robotic arm; another example is the anchor trolley for initial anchor support operations, and the end of the multi-degree-of-freedom robotic arm is equipped with an anchor drilling rig for drilling anchors.

[0003] In the whole process of tunnel construction excavation and support, in order to ensure the excavation of the tunnel required by the design and to ensure the safe construction, the actuator needs to be able to be accurately sent to the target position, which puts forward new requirements for the motion accuracy of the end of the multi-degree-of-freedom robot arm. In practice, after the assembly and production of the tunnel construction equipment is completed, the position of the end of the multi-degree-of-freedom robot arm will be calibrated. In the context of the rapid development of current visual measurement technology, the use of binocular or multi-eye cameras to perform three-dimensional measurement of target points has become an important industrial application. When calibrating the position of the end of the robot arm based on visual measurement technology, a calibration tool is required, in which a target is provided on the calibration tool, and multiple coding points are provided on the target. The coding points can reflect light for camera shooting, and the three-dimensional coordinate information of the coding points can be calculated based on the captured image information.

[0004] Currently, most commonly used calibration tools are flat-plate structures with a target on the plate. However, some tunnel construction equipment is equipped with a multi-degree-of-freedom robot end with rotational freedom. For flat-plate tooling, after the robot end rotates a certain angle, the target on the plate may not be captured by the fixed camera, resulting in recognition failure. In addition, there is only one target on the plate, which makes it impossible to calculate the posture information of the current position of the robot end. Summary of the invention

[0005] The purpose of the present invention is to provide a robotic arm boom calibration tool to solve the technical problems that the calibration tool used for the robotic arm boom in the prior art is difficult to adapt to the calibration of the boom with rotational freedom at the end and cannot calculate the posture information of the robotic arm end.

[0006] To achieve the above purpose, the technical solution of the mechanical arm bracket calibration tooling provided by the present invention is:

[0007] A robot arm bracket calibration tool comprises a main body, which is a regular N prism structure, wherein N≥3, one end of the main body is provided with a connection structure for being fixedly connected to the end of the robot arm bracket, at least two targets are installed on each side of the main body, a plurality of marking points are arranged on the targets, and each target is arranged along the axis direction of the main body so as to calculate the posture information of the end of the robot arm bracket according to the spatial coordinates of the marking points on the two targets.

[0008] As a further improvement, each side is numbered 1, 2...N in sequence, and among the targets installed on each side, at least one is an identification target for identifying the corresponding side number, so that the target information corresponds to the corresponding side one by one.

[0009] As a further improvement, two targets are provided on each side of the main body, and the two targets are spaced apart and arranged at both ends of the main body.

[0010] As a further improvement, a prism for reflecting the signal sent by the total station is installed at one end of the main body away from the connecting structure.

[0011] As a further improvement, the connection structure is a flange connection structure.

[0012] As a further improvement, the main body is a regular hexagonal prism structure.

[0013] As a further improvement, the marker points on the two targets used to calculate the pose information are defined as marker point A and marker point B, and the line connecting marker point A and marker point B is parallel to the axis direction of the subject.

[0014] As a further improvement, the main body is a box-type structure formed by splicing multiple plates.

[0015] The present invention is a pioneering invention, and its beneficial effects are as follows: the calibration tool in the present invention can be fixed to the end of the robotic arm through a connecting structure when in use, and moves with the end of the robotic arm. The calibration tool is a polygonal column structure as a whole, and targets are installed on each side. After the robotic arm rotates a certain angle, the calibration tool rotates a certain angle with it, and it can always be guaranteed that there is a target on the side that is at an angle that can be photographed by the camera, so that the calibration tool can be used for the calibration of the robotic arm with rotational freedom at the end of the arm. At the same time, at least two targets are installed on each side, and the targets are arranged along the axis direction of the main body. When calibrating, a mark point can be selected on each of the two targets. The posture of the calibration tool can be calculated based on the coordinate information of the two mark points, and then the posture information of the end of the robotic arm can be calculated, which expands the calibration function. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of a mechanical arm arm calibration tooling embodiment of the present invention at one viewing angle;

[0017] Figure 2 It is a structural schematic diagram of an embodiment of a robot arm bracket calibration tooling in the present invention from another perspective;

[0018] Figure 3 for Figure 1 Schematic diagram of the coordinate relationship between point A and point B at a certain position;

[0019] Figure 4 For Figure 1 Schematic diagram of the equation relationship when calculating the arm posture when points A and B are used as landmarks.

[0020] Description of reference numerals:

[0021] 1. Calibration tool; 101. Main body; 102. Target; 103. Prism; 104. Flange connection structure. DETAILED DESCRIPTION

[0022] In order to solve the problem that the existing calibration tooling for calibrating the end position of the mechanical arm boom based on visual calibration is difficult to use for the calibration of the boom with rotational freedom at the end and cannot calculate the posture of the end of the mechanical arm boom, the basic technical concept of the present invention is to provide a calibration tooling based on a multi-prism structure, one end of the calibration tooling can be used to be fixedly connected to the mechanical arm boom to be calibrated, each side is installed with a target that can be marked and identified by the camera, and each side is installed with at least two targets. In this way, when calibrating the boom, after the boom rotates a certain angle, it can be ensured that there is still a side facing the optical camera located in a fixed position, and the optical camera can still obtain the information of the target, so as to calibrate the position of the end of the mechanical arm boom. At the same time, one point of each of the two targets can be selected as a mark point for calculating the posture information, and then the geometric relationship can be converted to calibrate the posture information of the end of the mechanical arm boom, thereby expanding the function of the calibration tooling. The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0023] Specific embodiments of the mechanical arm bracket calibration tooling provided by the present invention:

[0024] The robot arm bracket calibration tooling provided in this embodiment is a polygonal column structure as a whole. Figure 1 and Figure 2A structure of a regular hexagonal prism is given as an example. Specifically, the calibration tool 1 includes a main body 101, and the main body 101 is a regular hexagonal prism structure, which includes a top surface, a bottom surface and six side surfaces. More specifically, the calibration tool 1 can be a box-type structure with a cavity inside, which is formed by splicing multiple plates. The specific splicing method can be welding or bolting. The inside of the box-type structure is hollow, which can make the calibration tool 1 lighter. Of course, in other embodiments, the case where the main body 101 is a solid columnar structure is not excluded. A connecting structure for fixed connection to the end of the boom is provided at one end of the main body 101. When the boom is calibrated, the calibration tool 1 can be fixed to the end of the boom through the connecting structure at one end of the main body 101. In this way, the calibration tool 1 can correspond to the position of the actuator installed at the end, such as a rock drill, an anchor drill, etc., when the boom moves.

[0025] Two targets 102 are installed on each side of the main body 101, and multiple marking points are arranged on the target 102, and the target 102 is arranged along the axis (height) direction of the main body 101. When performing arm calibration, the optical camera in the calibration system can capture, record and identify the information of the marking points, and calculate the position information of the calibration tool 1 to reflect the position information of the end of the arm. Specifically, the target 102 can use the CT series coding mark of Chenwei Technology Co., Ltd., and its specific structure can refer to the patent document with authorization announcement number CN208780192U, and the principle and algorithm based on the optical camera to shoot the target 102 and calculate the position coordinates are all prior art, which will not be described in detail here.

[0026] When the calibration tool 1 in this embodiment is used to calibrate the end of the arm, even if the end of the arm is rotated to a certain angle, it can still be ensured that a certain side of the main body 101 is located in a position that can be photographed by the camera, thereby completing a normal calibration.

[0027] One mark point can be selected from each of the two targets 102 installed on the side of the main body 101. After obtaining the spatial coordinates of the point, the position information of the end of the boom at this time can be obtained through geometric conversion, so as to reflect the position of the actuator installed at the end of the boom, so as to determine whether the actuator installed here, such as a rock drill, can drill holes according to the ideal position. Figure 1 As shown, the marking points A and B can be selected on the two targets 102, respectively. Figure 3 As shown in the figure, the three-dimensional coordinates of the marker point A are measured to be (x1, y1, z1), and the three-dimensional coordinates of the marker point B are measured to be (x2, y2, z2). Then, the vector coordinates of point A and point B are calculated based on the three-dimensional coordinates of the two marker points: like Figure 4As shown, according to the trigonometric relationship, it can be calculated that the distance between point A and point B on the x-axis is x1-x2, the distance on the y-axis is y1-y2, the distance on the z-axis is z1-z2, and the distance between the two points is Then the posture equations of the two landmark points are obtained as follows:

[0028]

[0029] When the above algorithm is used to calculate the posture, analysis of the above process shows that, in order to ensure the accuracy of the calculation results, the line connecting the selected marker points A and B is parallel to the axis direction of the main body.

[0030] It should be noted that the above example shows a case where the main body 101 is a regular hexagonal prism. On the basis that the main body 101 is a regular hexagonal prism, it can be ensured that after each rotation of a certain angle, there is a side surface that can be in a posture that basically faces the optical camera directly, thereby obtaining a more accurate measurement result. Moreover, the areas of several side surfaces of the regular hexagonal prism are relatively large, which can meet the normal installation of the target 102 without the overall size being too large. However, in other embodiments, the case where the main body 101 is a regular triangular prism, a regular quadrangular prism, ... a regular octagonal prism, etc. is not excluded.

[0031] It should also be noted that the above example shows a case where only two targets 102 are installed on the side. In order to calculate the position and posture, two targets 102 are the most basic case, but in other embodiments, it is not excluded that three or even more targets 102 are installed on the side.

[0032] Preferably, when only two targets 102 are installed on the side, Figure 1 As shown, two targets 102 are spaced apart and arranged at the two ends of the main body 101. In this way, the position of the calibration tool 1 can be fully utilized to install the targets 102, and the marking points on each target 102 can be more easily distinguished and identified.

[0033] In a further preferred embodiment, in order to accurately calibrate the terminal posture of the boom end after it is rotated to a certain angle, the numbering information in the targets 102 installed on different sides is not the same, so that the targets 102 and the corresponding sides correspond one to one. Specifically, for ease of understanding, taking the main body 101 as a regular hexagonal prism as an example, the sides are numbered 1, 2, 3, 4, 5, and 6 in sequence. Among the targets 102 installed on each side, at least one target 102 is used to identify the target 102 with the corresponding side number. The target 102 can be defined as an identification target, and its marking points are arranged in a specific manner and can be identified and distinguished. In this way, it is possible to accurately determine whether the boom end has rotated, and the position and posture calibration can still be completed after the rotation occurs, further expanding the function of the calibration tooling 1.

[0034] Considering the convenience of disassembly and assembly of the calibration tool 1, Figure 2 As shown, the connection structure for connecting the end of the boom provided at one end of the main body 101 preferably adopts a flange connection structure 104. When calibrating the boom, the end of the boom and the calibration tool 1 can be connected by inserting corresponding bolts. However, it should be noted that in other embodiments, the possibility of using a clamp, a buckle or the like as a connection structure is not completely excluded.

[0035] In addition, considering that the actual calibration process may result in insufficient accuracy if only visual calibration is used, in a further preferred embodiment, Figure 1 and Figure 2 As shown, a prism 103 is also installed at one end of the calibration tool 1 away from the connection structure. Accordingly, in addition to the optical camera, the robotic arm bracket calibration system also needs to be equipped with a total station, and the prism 103 is used to reflect the signal sent by the total station. The total station is a high-precision measuring device with higher measurement accuracy, so that the same calibration tool 1 can be used in conjunction with a measuring device based on machine vision, and can also be used in conjunction with a measuring device based on a total station.

[0036] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions recorded in the aforementioned embodiments without creative work, or replace some of the technical features therein with equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A robot arm bracket calibration tool, characterized in that: It includes a main body, which is a regular N prism structure, where N≥3. One end of the main body is provided with a connecting structure for fixedly connecting with the end of the robotic arm. At least two targets are installed on each side of the main body. A plurality of marking points are arranged on the targets. Each target is arranged along the axis direction of the main body to calculate the posture information of the end of the robotic arm according to the spatial coordinates of the marking points on the two targets.

2. The robot arm bracket calibration tool according to claim 1 is characterized in that: The side surfaces are numbered 1, 2, ..., N in sequence. Among the targets installed on each side surface, at least one is an identification target for identifying the corresponding side surface number, so that the target information corresponds to the corresponding side surface one by one.

3. The robot arm bracket calibration tool according to claim 1 or 2, characterized in that: Two targets are arranged on each side of the main body, and the two targets are arranged at two ends of the main body at intervals.

4. The robot arm bracket calibration tool according to claim 1 or 2, characterized in that: A prism for reflecting signals sent by the total station is installed at one end of the main body away from the connecting structure.

5. The robot arm bracket calibration tool according to claim 1 or 2, characterized in that: The connection structure is a flange connection structure.

6. The robot arm bracket calibration tool according to claim 1 or 2, characterized in that: The main body is a regular hexagonal prism structure.

7. The robot arm bracket calibration tool according to claim 1 or 2, characterized in that: The marker points on the two targets used to calculate the pose information are marker point A and marker point B, and the line connecting marker point A and marker point B is parallel to the axis direction of the subject.

8. The robot arm bracket calibration tool according to claim 1 or 2, characterized in that: The main body is a box-type structure made up of multiple panels.

Images