TW202146188A - Origin calibration method of manipulator - Google Patents

Abstract

The present disclosure provides an origin calibration method of a manipulator, comprising steps of: (a) controlling the manipulator to move according to a movement command, and utilizing a 3D (3-dimensional) measuring device to acquire the 3D coordinates of reference anchor points reached by the manipulator; (b) controlling the manipulator to move according to the movement command when an origin of the manipulator being offset, utilizing the 3D measuring device to acquire the 3D coordinates of actual anchor points reached by the manipulator, and acquiring a Jacobian matrix according to the actual anchor points; (c) acquiring a deviation of a rotation angle of the manipulator according to the Jacobian matrix, the 3D coordinates of the reference anchor points and the actual anchor points, and acquiring a compensating angle value according to the deviation; and (d) updating the rotation angle of the manipulator according to the compensating angle value so as to update the origin of the manipulator.

Description

Origin calibration method of robot arm

This case is about an origin calibration method, especially an origin calibration method of a robotic arm.

Today, robots are used more and more widely in various industries. When the robot is operating at the workstation, the robot may shift its origin due to some reasons (such as power failure or external impact). To this end, the existing response method is to withdraw the robot from the workstation and move the robot to the original factory or a specific environment for calibration. After the robot is calibrated, move the robot to the workstation to continue operation.

However, since the robot needs to be moved to the original factory or under a specific environment for calibration, and then the robot is moved back to the workstation after calibration, the moving process will take extra time and cost, and also lead to lower work efficiency. Furthermore, when the corrected robot returns to the workstation, it is necessary to re-teach the robot, which will also reduce work efficiency.

Therefore, it is an urgent need to develop an origin calibration method that can improve the above-mentioned conventional robot arm.

The purpose of this case is to provide a method for calibrating the origin of a robotic arm, which is to set a measuring device in the working environment of the robotic arm, and use the measuring device to realize the origin calibration of the robotic arm. Therefore, during the operation of the robot arm, if the origin of the robot arm is offset, the robot arm can be corrected in real time in the working environment of the robot arm, and there is no need to re-teach the point after the calibration is completed. In this way, the time and cost required for calibration can be saved, and the working efficiency of the robot arm can be greatly improved.

To achieve the above purpose, the present application provides a method for calibrating the origin of a robotic arm, wherein the robotic arm operates in a work space, and a three-dimensional measurement device is arranged in the work space, and the three-dimensional measurement device is constructed to measure the position of the robotic arm. The origin calibration method includes steps: (a) controlling the robotic arm to move according to the movement command, and using a three-dimensional measuring device to obtain the three-dimensional coordinates of a plurality of reference positioning points reached by the robotic arm; (b) generating offsets at the origin of the robotic arm. When moving, control the robotic arm to move according to the movement command, and use the three-dimensional measuring device to obtain the three-dimensional coordinates of the multiple actual positioning points reached by the robotic arm, and obtain the Jacobian matrix according to the multiple actual positioning points; (c) According to the Jacobian The matrix, the three-dimensional coordinates of the plurality of reference positioning points and the three-dimensional coordinates of the plurality of actual positioning points obtain the deviation of the rotation angle of the robot arm, and obtain the corrected angle value according to the deviation; and (d) update the rotation angle of the robot arm according to the corrected angle value; Rotate the angle to update the origin of the robotic arm.

Some typical embodiments embodying the features and advantages of the present case will be described in detail in the description of the latter paragraph. It should be understood that this case can have various changes in different aspects, all of which do not depart from the scope of this case, and the descriptions and diagrams therein are essentially for illustration purposes rather than limiting the present case.

FIG. 1 is a schematic three-dimensional structure diagram of a robot arm, a work space and a three-dimensional measuring device according to a preferred embodiment of the present invention, and FIG. 2 is a three-dimensional structure schematic diagram of the three-dimensional measuring device of FIG. 1 . As shown in FIG. 1 and FIG. 2 , the work platform 2 represents the work space where the robot arm 1 is in the operation process, but the actual form of the work space is not limited to this. The three-dimensional measuring device 3 is arranged on the working platform 2 and is constructed to measure the position of the robot arm 1 . Of course, in practical applications, the work platform 2 will also be provided with components or devices that the robot arm 1 moves with each other during the operation. Here, for the convenience of explaining the calibration process, only the three-dimensional measurement device on the work platform 2 is shown in the figure. 3. The robotic arm 1 may be, for example, but not limited to, a six-axis type robotic arm or a SCARA robotic arm. The three-dimensional measuring device 3 includes a spherical body 31 , a base 32 and three measuring modules 33 . The spherical body 31 is detachably assembled with the robot arm 1 , and is driven by the robot arm 1 to move or rotate synchronously. The three measurement modules 33 are disposed on the base 32 , wherein each measurement module 33 includes a measurement structure 34 and a position sensor. The three measurement structures 34 of the three measurement modules 33 move in the directions of the X-axis, the Y-axis and the Z-axis respectively, and all are in contact with the spherical body 31 . The position sensor is configured to sense the moving distance of the measurement structure 34 when the corresponding measurement structure 34 is pushed by the spherical body 31 , wherein the position sensor may be constituted by, for example, but not limited to, an optical ruler.

During the operation of the robot arm 1, the origin of the robot arm 1 may be shifted due to various unexpected conditions (such as but not limited to power failure or impact by external force). The origin calibration method is used to calibrate the robot arm 1.

As shown in FIG. 3 , FIG. 3 is a schematic flowchart of the method for calibrating the origin of the robot arm according to the preferred embodiment of the present invention. First, control the robot arm 1 to move according to the movement command, and use the three-dimensional measuring device 3 to obtain a plurality of reference positioning points reached by the robot arm 1 (step S1 ). Different operation actions are performed for multiple movements. Next, when the origin of the robotic arm 1 is offset, the robotic arm 1 is controlled to move according to the movement command, and the three-dimensional measuring device 3 is used to obtain a plurality of actual positioning points reached by the robotic arm 1 (step S2 ). The number of points is the same as the number of reference anchor points. Then, the correction information is calculated and obtained according to the plurality of reference positioning points and the plurality of actual positioning points (step S3). Finally, the origin of the robot arm 1 is updated according to the correction information (step S4). In this way, when the robot arm 1 operates in the workspace, if the origin of the robot arm 1 is offset, the robot arm 1 can be corrected in the workspace in real time, and there is no need to re-teach the point after the calibration is completed. In this way, the time and cost required for calibration can be saved, and the work efficiency of the robot arm 1 can be greatly improved.

Please refer to FIGS. 1 to 3 again, the above-mentioned three measurement structures 34 are respectively along the movable distances corresponding to each axis (X-axis, Y-axis and Z-axis) to jointly define the measurement space. In the origin calibration method In step S1 and step S2 , the spherical body 31 is driven by the robot arm 1 to move in the measurement space, and the sensing results of the three position sensors reflect the three-dimensional coordinates of the spherical body 31 . In some embodiments, the reference positioning point and the actual positioning point in steps S1 and S2 of the origin calibration method are the three-dimensional coordinates of the center of the spherical body 31 measured by the three-dimensional measuring device 3 .

The spherical body 31 is detachably assembled with the robot arm 1 , so the robot arm 1 can be assembled with the spherical body 31 only when there is a need for calibration, so as to perform the origin calibration method shown in FIG. 3 . What's more, the robot arm 1 can be assembled to the spherical body 31 only at the point of demand measurement. Specifically, the robot arm 1 can be assembled to the spherical body 31 only in steps S1 and S2 of the origin calibration method. .

In some embodiments, the robotic arm 1 is assembled with the tool 4, and the tool 4 is driven by the robotic arm 1 to operate on the work platform 2. When the robotic arm 1 is assembled with the tool 4, the robotic arm 1 is also It can be assembled to the spherical body 31 of the three-dimensional measuring device 3 at the same time. In this way, when the robot arm 1 is calibrated, it is not necessary to remove the tool 4 before calibration. Therefore, after the calibration is completed, there is no need to reinstall the tool 4 and perform corresponding adjustment, thereby saving the calibration process and time-consuming, and indirectly elevating the robot arm 1 work efficiency.

The following is an example to illustrate how to obtain the correction information according to a plurality of reference positioning points and a plurality of actual positioning points.

(1) 其中，P 代表實際定位點的三維座標，

代表參考定位點的三維座標，i 代表機器手臂1依據移動命令所執行的操作動作的次序，

代表雅可比矩陣，

代表機器手臂1的轉動角度θ 的偏差量。根據等式 (1) 變化可取得等式 (2)。

(2) 因此，在步驟S3中，根據參考定位點的三維座標、實際定位點的三維座標及雅可比矩陣，可計算取得機器手臂1的轉動角度的偏差量，並進一步通過該偏差量取得補正資訊的補正角度值。藉此，在步驟S4中，即可依據補正角度值更新機器手臂1的轉動角度，從而更新機器手臂1的原點，使機器手臂1的參考定位點與實際定位點一致，實現對機器手臂1的校正。In step S1, the three-dimensional measuring device 3 is used to measure and obtain the three-dimensional coordinates of the reference positioning point. In step S2, the three-dimensional measuring device 3 is used to obtain the three-dimensional coordinates of the actual positioning points, and a Jacobian matrix is obtained according to the plurality of actual positioning points. Since the origin of the robot arm 1 is offset, the corresponding rotation angle of the robot arm 1 is deviated. Therefore, when the robot arm 1 is controlled by the same movement command to move, the actual positioning point reached will be different from the original reference positioning. The points are different, wherein the relationship between the reference positioning point, the actual positioning point and the deviation of the rotation angle of the robot arm 1 is as shown in Equation (1).

(1) Among them, P represents the three-dimensional coordinates of the actual positioning point,

Represents the three-dimensional coordinates of the reference positioning point, i represents the sequence of operations performed by the robot arm 1 according to the movement command,

represents the Jacobian matrix,

It represents the deviation of the rotation angle θ of the robot arm 1 . Equation (2) can be obtained by changing from Equation (1).

(2) Therefore, in step S3, according to the three-dimensional coordinates of the reference positioning point, the three-dimensional coordinates of the actual positioning point, and the Jacobian matrix, the deviation amount of the rotation angle of the robot arm 1 can be calculated and obtained, and further correction is obtained through the deviation amount The correction angle value of the information. In this way, in step S4, the rotation angle of the robot arm 1 can be updated according to the corrected angle value, thereby updating the origin of the robot arm 1, so that the reference positioning point of the robot arm 1 is consistent with the actual positioning point, so as to realize the adjustment of the robot arm 1. 's correction.

To sum up, the present application provides a method for calibrating the origin of a robotic arm, which is based on setting a measuring device in the working environment of the robotic arm, and using the measuring device to realize the origin calibration of the robotic arm. Therefore, during the operation of the robot arm, if the origin of the robot arm is offset, the robot arm can be corrected in real time in the working environment of the robot arm, and there is no need to re-teach the point after the calibration is completed. In this way, the time and cost required for calibration can be saved, and the working efficiency of the robot arm can be greatly improved. In addition, when the robot arm is connected to the tool, the robot arm can also be connected to the spherical body of the three-dimensional measuring device at the same time. In this way, when the robot arm is calibrated, it is not necessary to remove the tool before calibration. Therefore, after the calibration is completed, there is no need to reinstall the tool to adjust accordingly, which can save the calibration process and time-consuming, and indirectly improve the work efficiency of the robot arm.

It should be noted that the above-mentioned preferred embodiments are only proposed to illustrate the present case, and the present case is not limited to the described embodiments, and the scope of the present case is determined by the scope of the appended patent application. And this case can be modified by Shi Jiangsi, a person who is familiar with this technology, but none of them can be protected as attached to the scope of the patent application.

1: Robot arm 2: Work Platform 3: 3D measuring device 31: Sphere 32: Pedestal 33: Measurement module 34: Measuring Structure 4: Tools S1, S2, S3, S4: Steps of the origin calibration method

FIG. 1 is a schematic three-dimensional structure diagram of a robot arm, a work space and a three-dimensional measurement device according to a preferred embodiment of the present invention.

FIG. 2 is a schematic three-dimensional structure diagram of the three-dimensional measuring device of FIG. 1 .

FIG. 3 is a schematic flowchart of a method for calibrating the origin of a robot arm according to a preferred embodiment of the present invention.

S1, S2, S3, S4: Steps of the origin calibration method

Claims (8)

An origin calibration method of a robotic arm, wherein the robotic arm operates in a workspace, a three-dimensional measuring device is arranged in the working space, and the three-dimensional measuring device is structured to measure the position of the robotic arm, and the origin calibration method comprises: step: (a) controlling the robotic arm to move according to a movement command, and using the three-dimensional measuring device to obtain the three-dimensional coordinates of a plurality of reference positioning points reached by the robotic arm; (b) When the origin of the robotic arm is offset, control the robotic arm to move according to the movement command, and use the three-dimensional measuring device to obtain the three-dimensional coordinates of a plurality of actual positioning points reached by the robotic arm, and obtaining a Jacobian matrix according to the plurality of actual positioning points; (c) obtaining a deviation of a rotation angle of the robotic arm according to the Jacobian matrix, the three-dimensional coordinates of the plurality of reference positioning points, and the three-dimensional coordinates of the plurality of actual positioning points, and obtaining a deviation according to the deviation the corrected angle value; and (d) updating the rotation angle of the robotic arm according to the correction angle value to update the origin of the robotic arm. The origin calibration method according to claim 1, wherein the movement command includes controlling the robot arm to perform multiple movements with different operation actions. The origin calibration method according to claim 1, wherein in the step (c), the relationship between the plurality of reference positioning points, the plurality of actual positioning points and the deviation of the rotation angle of the robot arm as follows:

Among them, P represents the three-dimensional coordinates of the actual positioning point,

represents the three-dimensional coordinate of the reference positioning point, i represents the order of the operation actions performed by the robotic arm according to the movement command,

represents the Jacobian matrix,

represents the deviation of the rotation angle of the robotic arm. The origin calibration method as claimed in claim 1, wherein the three-dimensional measurement device comprises: a spherical body, detachably assembled with the robotic arm, and driven by the robotic arm to move or rotate synchronously; a pedestal; and Three measurement modules are arranged on the base, wherein each of the measurement modules includes a measurement structure and a position sensor, and the three measurement structures of the three measurement modules are respectively on the X-axis and the Y-axis and the Z-axis direction, and both are in contact with the spherical body, the position sensor is configured to measure the moving distance of the measuring structure when the corresponding measuring structure is pushed by the spherical body, Three of the measurement structures respectively define a measurement space along the movable distances corresponding to the respective axes. In the step (a) and the step (b), the spherical body is driven by the robot arm to move in the measurement space. Moving, the sensing results of the three position sensors reflect the three-dimensional coordinates of the spherical body. The origin calibration method according to claim 4, wherein the robot arm is assembled to a tool, the tool is driven by the robot arm to operate in the workspace, and the robot arm is detachable when assembled to the tool is assembled to the spherical body of the three-dimensional measuring device. The origin calibration method as claimed in claim 4, wherein the robotic arm is assembled to the spherical body of the three-dimensional measuring device only in the steps (a) and (b). The origin calibration method according to claim 4, wherein in the step (a) and the step (b), the plurality of reference positioning points and the plurality of actual positioning points are the spherical shape measured by the three-dimensional measuring device The three-dimensional coordinates of the sphere center of the body. The origin calibration method according to claim 1, wherein the robotic arm is a six-axis robotic arm or a SCARA robotic arm.

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