Method for adjusting the synchronism of the axes of a multi-axis robot

Abstract

This invention discloses a method for adjusting the synchronization of axes in a multi-axis robot, comprising: planning the motion trajectory of the multi-axis robot while ensuring that each axis has joint angle changes; collecting feedback and theoretical joint angle data of each axis and feedback and theoretical end-effector position data of TCP control points during the multi-axis robot's movement along the motion trajectory; calculating the end-effector position deviation value and joint angle deviation value of each axis; comparing whether the end-effector position deviation value of each axis is greater than a first threshold; if the joint position deviation value of a certain axis is greater than the first threshold, then reducing the position loop proportional gain of that axis; based on the joint angle deviation value and joint angle change trend of each axis, determining whether the motor response of each axis is fast or slow; if the motor response of a certain axis is too fast, then reducing the speed loop proportional gain parameter of the corresponding axis; if the motor response of a certain axis is too slow, then increasing the speed loop proportional gain parameter of the corresponding axis. This invention enables multi-axis robots to achieve more accurate parameter adjustment.

Description

Technical Field

[0001] This invention relates to the field of multi-axis robot technology, and in particular to a method for adjusting the synchronization of the axes of a multi-axis robot. Background Technology

[0002] Since each joint of a multi-axis robot is driven by a servo motor, even if the three-loop (current loop, speed loop, and position loop) control parameters of the servo system use accurate theoretical values ​​under the coordinated control of multiple motors, there will still be slight differences in the response of each axis due to the individual differences of the motors. Even with the same three-loop control parameters, motors of the same specification will still have slight differences in response.

[0003] For position loop proportional gain, position loop gain is a crucial parameter in servo motor control systems, directly impacting system response speed and stability. Excessive position loop gain can cause system oscillations, affecting stability; conversely, insufficient gain leads to slow response, impacting control accuracy and speed. Poor gain matching between axes can cause fluctuations in the motion trajectory during movement, also affecting accuracy.

[0004] The proportional gain of the speed loop directly affects the servo system's response speed to speed changes. The faster the multi-axis robot moves, the more significant the impact of the response speed of each axis motor on the trajectory. For example, if the theoretical trajectory is a straight line, the actual trajectory of a multi-axis robot moving at high speed may be an arc due to the slightly faster or slower response of each axis.

[0005] Currently, robot manufacturers directly provide a theoretical value for three-ring parameters to control multi-axis robots, ignoring these subtle changes. However, for applications requiring high-precision control of multi-axis robots, ignoring these subtle changes is inappropriate. Therefore, it is necessary to design a method for adjusting the synchronization of each axis of a multi-axis robot to overcome trajectory changes caused by poor synchronization of the multi-axis robot. Summary of the Invention

[0006] This invention provides a method for adjusting the synchronization of each axis of a multi-axis robot to solve the technical problems in the prior art.

[0007] The technical solution adopted in this invention is: to provide a method for adjusting the synchronization of each axis of a multi-axis robot, comprising:

[0008] Plan the motion trajectory of a multi-axis robot while ensuring that each axis has joint angle changes;

[0009] Collect feedback and theoretical joint angle data of each axis and feedback and theoretical end position data of TCP control points during the movement of the multi-axis robot along the motion trajectory;

[0010] Calculate the end position deviation between the feedback end position data of the TCP control point motion trajectory and the corresponding theoretical end position data, and calculate the joint angle deviation between the feedback joint angle data of each axis and the corresponding theoretical joint angle data.

[0011] Compare whether the end position deviation curve of the motion trajectory diverges and whether the deviation of the end point of the stroke is greater than the first threshold. If this occurs, manually reduce the proportional gain of the position loop of that axis.

[0012] Based on the joint angle deviation and joint angle change trend of each axis, determine whether the motor response of each axis is fast or slow. If the motor response of a certain axis is too fast, manually reduce the speed loop proportional gain parameter of the corresponding axis; if the motor response of a certain axis is too slow, manually increase the speed loop proportional gain parameter of the corresponding axis.

[0013] Furthermore, the theoretical joint angle data and theoretical end-effector position data of the multi-axis robot at the first operating speed are used as reference values; the feedback joint angle data and feedback end-effector position data of the multi-axis robot at the second operating speed are used as comparison values; the second operating speed is greater than the first operating speed.

[0014] Furthermore, the first operating speed is ≤50mm / s, and the second operating speed is ≥100mm / s.

[0015] Furthermore, by calculating the spatial distance between a theoretical terminal location data point and all feedback terminal location data points, the feedback terminal location data point with the smallest spatial distance to the theoretical terminal location data point is identified as the corresponding data point, thereby obtaining the feedback terminal location data point corresponding to all theoretical terminal location data point.

[0016] Furthermore, find the point in the joint angle deviation graph where the absolute value of the deviation is the largest and exceeds the set threshold, and the axis corresponding to that point;

[0017] If the joint angle deviation value at this point is >0, and the trend of the corresponding shaft joint angle change is increasing, then the motor response is too fast, and the speed loop proportional gain parameter of the corresponding shaft needs to be reduced.

[0018] If the joint angle deviation value at this point is <0, and the trend of the corresponding shaft joint angle change is increasing, then the motor response is too slow, and the speed loop proportional gain parameter of the corresponding shaft needs to be increased.

[0019] If the joint angle deviation value at this point is >0, and the trend of the corresponding shaft joint angle change is decreasing, then the motor response is too slow, and the speed loop proportional gain parameter of the corresponding shaft needs to be increased.

[0020] If the joint angle deviation value at that point is <0, and the corresponding shaft joint angle changes in a decreasing trend, then the motor response is too fast, and the speed loop proportional gain parameter of the corresponding shaft needs to be reduced.

[0021] Furthermore, the first threshold value ranges from 0.1 to 0.4 mm. Preferably, it is 0.1 to 0.2 mm; more preferably, it is 0.1 mm.

[0022] Furthermore, if the joint position deviation value of a certain axis is greater than the second threshold, then amplitude adjustment is performed; the second threshold is greater than the first threshold.

[0023] Furthermore, if the ratio of the second threshold to the first threshold is greater than or equal to 2, the adjustment range is 0.01-0.1; if the deviation is greater than 0.2mm, the adjustment range is 0.1; if the ratio of the second threshold to the first threshold is greater than 1 and less than or equal to 2, the adjustment range is 0.01-0.05; if the deviation is within 0.15mm, the adjustment range is 0.05.

[0024] Furthermore, the motion trajectory is a straight line from the lower left corner of the robot base to the upper right corner.

[0025] The beneficial effects of this invention are: this invention enables multi-axis robots to achieve more accurate parameter adjustment, improve robot synchronization, and after manual adjustment, its synchronization can be adjusted from 0.4 to 0.2 mm level, providing a better foundation for further automatic machine adjustment. Attached Figure Description

[0026] Figure 1 This is the terminal XYZ deviation diagram disclosed in an embodiment of the present invention;

[0027] Figure 2 This is another end XYZ deviation diagram disclosed in an embodiment of the present invention;

[0028] Figure 3 This is a diagram showing the joint angle deviation disclosed in an embodiment of the present invention;

[0029] Figure 4 This is another joint angle deviation diagram disclosed in an embodiment of the present invention;

[0030] Figure 5 This is a diagram showing the joint angle variation disclosed in an embodiment of the present invention;

[0031] Figure 6 This is another diagram showing the change of joint angles disclosed in an embodiment of the present invention;

[0032] Figure 7 This is a flowchart of a method for adjusting the synchronization of each axis of a multi-axis robot, as disclosed in an embodiment of the present invention. Detailed Implementation

[0033] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0034] It should be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0035] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0036] As used in this specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrases "if determined" or "if [described condition or event] is detected" may be interpreted, depending on the context, as "once determined," "in response to determination," "once [described condition or event] is detected," or "in response to detection of [described condition or event]."

[0037] Example 1:

[0038] This embodiment discloses a method for adjusting the synchronization of each axis of a multi-axis robot. This method mainly involves adjusting the three-loop control parameters of each axis of the multi-axis robot to achieve better linkage control of each axis and improve the robot's synchronization. Furthermore, the robot's synchronization accuracy can reach the 0.2mm level after parameter adjustment.

[0039] These control parameters are for PID control of a single axis of the robot. Among them, the position loop proportional gain and the velocity loop proportional gain in PID control have the greatest impact on the synchronization of multi-axis robots. Therefore, the main focus is on adjusting the position loop proportional gain and the velocity loop proportional gain.

[0040] See Figure 7 The method specifically includes:

[0041] S1: Plan the motion trajectory of the multi-axis robot while ensuring that each axis has joint angle changes.

[0042] Specifically, multi-axis robots can be three-axis, four-axis, five-axis, six-axis, seven-axis, etc. The motion trajectory is selectable; for example, a straight line can be taught from the lower left corner of the robot base to the upper right corner.

[0043] S2: Collect feedback and theoretical joint angle data of each axis, as well as feedback and theoretical end position data of TCP control points, during the movement of the multi-axis robot along the motion trajectory.

[0044] Specifically, the robot outputs joint angle data and end-effector position data. Joint angle data represents the angle changes of each axis as the robot moves along a trajectory, while end-effector position data represents the spatial position changes of the end-effector control point based on the robot's base coordinate system. The data types include theoretical data and feedback data. Theoretical data consists of theoretical values ​​calculated by the control system based on trajectory planning, while feedback data represents the actual values ​​output in real-time by the robot servo system based on the robot's real-time motion.

[0045] Due to factors such as operating trajectory, operating speed, and individual differences in motors, it is difficult to find theoretical data that perfectly matches the planned motion trajectory. The inventors discovered that when the robot operates at a speed of 50 mm / s or less, it has virtually no impact on the end-effector trajectory. Therefore, to observe the influence of the response speed of each axis on the robot's end-effector trajectory, robot joint angle data and end-effector position data at different speeds are compared. This comparison requires a baseline value and a comparison value. Since the theoretical values ​​at low speeds are relatively more accurate, a specific implementation can use the theoretical joint angles and theoretical end-effector position data at 20 mm / s as the baseline values. The feedback data at high speeds corresponds to the actual speed scenario of the robot's movement; high speeds are greater than or equal to 100 mm / s. A specific implementation can use the robot's feedback joint angles and feedback end-effector position data at 200 mm / s as the comparison value.

[0046] S3: Calculate the end position deviation of the motion trajectory between the feedback end position data of the TCP control point and the corresponding theoretical end position data, and calculate the joint angle deviation between the feedback joint angle data of each axis and the corresponding theoretical joint angle data.

[0047] Because the amount of theoretical data and actual robot feedback data does not correspond—feedback data is generally more than theoretical data—we calculate the spatial distance between a theoretical end-effector position (one point equals one data point) and all feedback end-effector positions. The feedback end-effector position with the smallest spatial distance to the theoretical end-effector positions is the corresponding feedback position. This process is used to find the feedback data points corresponding to all theoretical data points. The difference between the feedback joint angle and the corresponding theoretical joint angle is used to obtain the joint angle deviation. Finally, the spatial distance between the theoretical end-effector position data and the corresponding feedback end-effector position is calculated to obtain the joint end-effector position deviation.

[0048] S4: Compare whether the end position deviation curve of the motion trajectory diverges and whether the end point of the stroke is greater than the first threshold. If this occurs, reduce the proportional gain of the position loop of that axis.

[0049] This allows us to obtain the deviation values ​​of the end-effector position and the joint angle, such as... Figure 1 and Figure 2 For the end-position deviation diagram, check if the deviation of the point at the end of the stroke in the diagram is higher than the first threshold. The first threshold ranges from 0.1 to 0.4 mm, preferably 0.1 to 0.2 mm, and more preferably 0.1 mm. If it is higher than the first threshold, it indicates that the position loop value is set too high, and the position loop proportional gain needs to be reduced, adjusted according to the actual deviation value. If the deviation value reaches the second threshold, and the second threshold is more than twice the first threshold (inclusive), the adjustment range is 0.01 to 0.1; if the second threshold is more than once but less than twice the first threshold (exclusive), the adjustment range is 0.01 to 0.05. Taking a first threshold of 0.1 mm as an example, if the second threshold is set to 0.2 mm, the adjustment range is set to 0.1; if the second threshold is 0.15 mm, the adjustment range is 0.05. If the deviation value is greater than 0.1 mm, adjust the position loop proportional gain value by 0.05 increments. For example, if the deviation value is -0.15 mm, the gain value is 1.1, increase it to 1.15 and observe the effect. If the deviation is greater than 0.2mm, adjust the position loop proportional gain value by an increment of 0.01. For example, if the deviation is 0.28mm, the gain value is 1.1. Observe the effect after reducing the gain to 1.

[0050] S5: Based on the joint angle deviation and joint angle change trend of each axis, determine whether the motor response of each axis is fast or slow. If the motor response of a certain axis is too fast, reduce the speed loop proportional gain parameter of the corresponding axis; if the motor response of a certain axis is too slow, increase the speed loop proportional gain parameter of the corresponding axis.

[0051] Specifically, such as Figures 3-6By observing the joint angle curves along the six axes of the joint angle change graph, we can see that as the joint angle increases, the graph shows an increasing trend; conversely, as the joint angle decreases, the graph shows a decreasing trend. Therefore, we can conclude that:

[0052] If the joint angle deviation value at this point is >0, and the trend of the corresponding shaft joint angle change is increasing, then the motor response is too fast, and the speed loop proportional gain parameter of the corresponding shaft needs to be reduced.

[0053] If the joint angle deviation value at this point is <0, and the trend of the corresponding shaft joint angle change is increasing, then the motor response is too slow, and the speed loop proportional gain parameter of the corresponding shaft needs to be increased.

[0054] If the joint angle deviation value at this point is >0, and the trend of the corresponding shaft joint angle change is decreasing, then the motor response is too slow, and the speed loop proportional gain parameter of the corresponding shaft needs to be increased.

[0055] If the joint angle deviation value at that point is <0, and the corresponding shaft joint angle changes in a decreasing trend, then the motor response is too fast, and the speed loop proportional gain parameter of the corresponding shaft needs to be reduced.

[0056] To address the issue of slightly faster or slower response times during motor start-stop, adjust the speed loop proportional gain parameter. If the motor response is slightly faster, decrease the speed loop proportional gain parameter for the corresponding axis; if the motor response is slightly slower, increase the speed loop proportional gain parameter for the corresponding axis. The adjustment increment is 2.

[0057] Adjustments are made for each axis to ensure that the end-point XYZ deviation of all axes is within 0.1mm and the joint angle deviation is within 0.1° (since the designed motion trajectory cannot cover all situations, the actual synchronization accuracy of the robot will be slightly worse, around 0.2mm). This completes the adjustment of the position loop proportional gain and the velocity loop proportional gain.

[0058] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for adjusting the synchronism of the axes of a multi-axis robot, characterized in that, include: Plan the motion trajectory of a multi-axis robot while ensuring that each axis has joint angle changes; Collect feedback and theoretical joint angle data of each axis, as well as feedback and theoretical end-effector position data of TCP control points, during the movement of the multi-axis robot along the motion trajectory. Calculate the end position deviation between the feedback end position data of the TCP control point motion trajectory and the corresponding theoretical end position data, and calculate the joint angle deviation between the feedback joint angle data of each axis and the corresponding theoretical joint angle data. Compare whether the end position deviation curve of the motion trajectory diverges and whether the deviation of the end point of the stroke is greater than the first threshold. If this occurs, manually reduce the proportional gain of the position loop of that axis. Based on the joint angle deviation and joint angle change trend of each axis, determine whether the motor response of each axis is fast or slow. If the motor response of a certain axis is too fast, manually reduce the speed loop proportional gain parameter of the corresponding axis; if the motor response of a certain axis is too slow, manually increase the speed loop proportional gain parameter of the corresponding axis. The theoretical joint angle data and theoretical end-effector position data of the multi-axis robot at the first operating speed are used as reference values; The feedback joint angle data and feedback end-effector position data of the multi-axis robot at the second operating speed are used as comparison values; The second operating speed is greater than the first operating speed.

2. The method of claim 1, wherein, The first operating speed is ≤50mm / s, and the second operating speed is ≥100mm / s.

3. The method for adjusting the synchronization of each axis of a multi-axis robot according to claim 1, characterized in that, By calculating the spatial distance between a theoretical terminal location data point and all feedback terminal location data points, the feedback terminal location data point with the smallest spatial distance to the theoretical terminal location data point is identified as the corresponding data point. This allows us to obtain the feedback terminal location data point corresponding to all theoretical terminal location data points.

4. The method for adjusting the synchronization of each axis of a multi-axis robot according to claim 1, characterized in that, Find the point in the joint angle deviation graph where the absolute value of the deviation is the largest and exceeds a set threshold, and the axis corresponding to that point; If the joint angle deviation value at this point is >0, and the trend of the corresponding shaft joint angle change is increasing, then the motor response is too fast, and the speed loop proportional gain parameter of the corresponding shaft needs to be reduced. If the joint angle deviation value at this point is <0, and the trend of the corresponding shaft joint angle change is increasing, then the motor response is too slow, and the speed loop proportional gain parameter of the corresponding shaft needs to be increased. If the joint angle deviation value at this point is >0, and the trend of the corresponding shaft joint angle change is decreasing, then the motor response is too slow, and the speed loop proportional gain parameter of the corresponding shaft needs to be increased. If the joint angle deviation value at that point is <0, and the corresponding shaft joint angle changes in a decreasing trend, then the motor response is too fast, and the speed loop proportional gain parameter of the corresponding shaft needs to be reduced.

5. The method for adjusting the synchronization of each axis of a multi-axis robot according to claim 1, characterized in that, The first threshold value ranges from 0.1 to 0.4 mm.

6. The method for adjusting the synchronization of each axis of a multi-axis robot according to claim 1, characterized in that, If the joint position deviation of a certain axis is greater than the second threshold, then amplitude adjustment is performed; the second threshold is greater than the first threshold.

7. The method for adjusting the synchronization of each axis of a multi-axis robot according to claim 6, characterized in that, If the ratio of the second threshold to the first threshold is greater than or equal to 2, the adjustment range is 0.01-0.1; if the ratio of the second threshold to the first threshold is greater than 1 and less than or equal to 2, the adjustment range is 0.01-0.

05.

8. The method for adjusting the synchronization of each axis of a multi-axis robot according to claim 1, characterized in that, The trajectory is a straight line from the lower left corner of the robot base to the upper right corner.

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