Calibration equipment and calibration method for work task point of industrial robot

Abstract

The invention relates to the technical field of robots, in particular to calibration equipment and a calibration method for work task points of an industrial robot, and the calibration equipment comprises the industrial robot, a laser tracker, a target ball, a joint type coordinate measuring machine seat and a joint type coordinate measuring machine, a laser tracker is used for determining the position relation between a plurality of measuring bases and the base coordinates of the robot during primary calibration, the joint type coordinate measuring machine is moved to different positions to reach the positions of all work task calibration points and calibrated through the laser tracker, and then the tail end of the industrial robot is moved to the position of a preset calibration point; and at the moment, deviation exists between the tail end position and the preset calibration point, the tail end coordinates of the industrial robot are measured through the joint type coordinate measuring machine, and therefore the tail end position error amount is obtained. The problems that numerous calibration pieces need to be installed for calibration of the calibration block and extra errors are introduced by human factors are solved, and the calibration cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of robots, and particularly relates to a calibration device and a calibration method for industrial robot work task points. Background Art

[0002] Currently, for the calibration of the pose of the end effector of an industrial robot, mainly methods such as external measurement systems (such as laser trackers, etc.), calibration blocks, and articulated coordinate measuring machines are used. After long-term production work, the calibrated industrial robot will have certain pose errors, resulting in problems such as being unable to continue to complete the preset work tasks, and it is necessary to recalibrate it.

[0003] When recalibrating, due to limited processing space and complex actual working conditions, such as machining inside complex cavities, assembling large-sized workpieces, etc., using a laser tracker requires additional measurement equipment to receive the laser beam emitted to hidden positions, increasing the calibration cost; using calibration blocks for calibration, the measured relative distance is limited, and for the case of too many work task calibration points, installing calibration parts is time-consuming and laborious and is prone to additional errors caused by human factors; the articulated coordinate measuring machine can bend in multiple directions, but the determination of its measurement coordinate system and measurement range limit that some work task calibration points where errors are likely to occur cannot be accurately measured.

[0004] Therefore, the present invention proposes a calibration device and method for industrial robot work task points to solve the above problems. Summary of the Invention

[0005] In order to solve the technical problems existing in the above-mentioned prior art, the present invention provides a calibration device and a calibration method for industrial robot work task points.

[0006] To solve the above technical problems, the present invention provides the following technical solution: A calibration device for industrial robot work task points, including an industrial robot, a laser tracker, a target ball, an articulated coordinate measuring machine base, and an articulated coordinate measuring machine;

[0007] The industrial robot is fixedly installed at a specified position on the production line, and the target ball is configured at the end of the movable end of the industrial robot. The target ball is used to reflect the laser signal emitted by the laser tracker to obtain the position information of the end of the industrial robot in real time;

[0008] The laser tracker is arranged along the outer edge of the working area of the industrial robot, and the laser emission direction of the laser tracker covers all work task calibration points within the moving radius of the industrial robot;

[0009] At least three groups of the articulated coordinate measuring machine bases are evenly distributed along the working area of the industrial robot and are on the same horizontal reference plane as the industrial robot. Each group of bases is provided with a detachable mounting interface;

[0010] The articulated coordinate measuring machine is connected to one group of the articulated coordinate measuring machine bases through the mounting interface, and a high-precision probe is configured at its end for contact measurement of the spatial coordinates of the calibration points of the work task;

[0011] The laser tracker and the articulated coordinate measuring machine are connected to the same control terminal through a data bus to realize real-time synchronization and comparative analysis of the measurement data.

[0012] Preferably, the control terminal is built-in with an error compensation algorithm, and the algorithm includes: a noise suppression module based on Kalman filtering for eliminating the instantaneous measurement error of the laser tracker, and an adaptive learning module based on neural network for predicting the long-term pose deviation caused by the joint wear of the industrial robot.

[0013] A calibration method for a calibration measurement device for the work task points of an industrial robot includes the following steps:

[0014] Step S1, perform initial calibration on the positions of the articulated coordinate measuring machine bases and the articulated coordinate measuring machine;

[0015] Step S2, install the articulated coordinate measuring machine, calibrate the work task calibration points through the articulated coordinate measuring machine, and control the industrial robot to carry the target ball to run to the work task calibration points;

[0016] Step S3, compensate for the running error of the controlled industrial robot until the error approaches zero.

[0017] Preferably, the S1 includes:

[0018] Step S11, install the industrial robot at a specified position, disperse no less than three groups of articulated coordinate measuring machine bases within the moving radius of the industrial machine, the articulated coordinate measuring machine bases and the industrial machine are on the same horizontal ground, and set the laser tracker on the same horizontal ground. The laser tracker is at least 1 m away from the three groups of articulated coordinate measuring machine bases;

[0019] Step S12, establish a first measurement coordinate system {x1, y1, z1} with the position of the laser tracker as the origin;

[0020] Step S13, measure through the laser tracker and obtain the coordinates {x A , y A , z A} of the base coordinate of the industrial robot in the first measurement coordinate system {x1, y1, z1} and record it as and record it as the reference point;

[0021] Step S14, measure by a laser tracker and obtain the coordinate positions {x B1 , y B1 , z B1}, {x B2 , y B2 , z B2} and {x B3 , y B3 , z B3} of each articulated coordinate measuring machine base in the first measurement coordinate system {x1, y1, z1}, and record them as to form a base position database;

[0022] Step S15, record the position matrix of the base coordinate and the second measurement coordinate system as

[0023] The position transformation matrix of the base coordinate and the second measurement coordinate system is

[0024] Step S16, record {x1, y1, z1}, {x A , y A , z A} and {x B , y B , z B} respectively.

[0025] Preferably, step S1 further includes:

[0026] Step S17, fit the reference point and the base position data by the least square method to verify the consistency of the global coordinate system. If the deviation exceeds the threshold, re-calibrate.

[0027] Preferably, step S2 includes:

[0028] Step S21, establish a second measurement coordinate system {x 12 , y 12 , z 12} with the first set position of the articulated coordinate measuring machine as the origin. Operate the articulated coordinate measuring machine to adjust the end of the articulated coordinate measuring machine to multiple preset calibration points of the work tasks in sequence, and obtain the task coordinate group T 12 , y 12 , z 12} in the second measurement coordinate system {x i = {T1, T2,..., T n} of each preset calibration point of the work task through the articulated coordinate measuring machine;

[0029] Step S22, through the task coordinate group Ti And the position transformation matrix between the base coordinate system and the second measurement coordinate system Get the joint angle θ that the industrial robot needs to rotate Bi ;

[0030]

[0031] Step S23, controlling the industrial robot to drive the target ball at the end of the movable end to move to each preset calibration point of each work task in sequence according to the joint angle, and pausing at each preset calibration point of the work task;

[0032] Step S24, using an articulated coordinate measuring machine to measure and obtain the actual coordinate set N of the target ball at each preset calibration point of the work task i ={N1, N1, ..., N n};

[0033] Step S25: group the task coordinates into i With the actual coordinate group N i Compare, if the comparison result satisfies |T i -N i |≤∈, ∈ is the preset tolerance, then the calibration point is recorded as a valid calibration point; otherwise, step S3 is triggered to perform error compensation.

[0034] Preferably, step S3 comprises:

[0035] Step S31, according to the task coordinate group T of the articulated coordinate measuring machine in the second measurement coordinate system i and the actual coordinate set N of the end position of the industrial robot 1 in the second coordinate system i Obtain the relative offset Δ;

[0036] Δ=T i -N i

[0037] Step S32, inputting the relative offset Δ obtained in step S31 into the control system of the industrial robot, generating an inverse kinematics compensation instruction, and adjusting the robot end trajectory;

[0038] Step S33, repeating steps S24-S26 until the offset Δ of all calibration points satisfies |Δ|≤∈;

[0039] Preferably, the step S3 further comprises:

[0040] Step S34: if there are still out-of-tolerance points after compensation, they are marked as abnormal points, and the theoretical coordinates of the points are remeasured by an articulated coordinate measuring machine to eliminate mechanical structure deformation or environmental interference factors.

[0041] Preferably, the step S3 further comprises:

[0042] In step S35, move the articulated coordinate measuring machine to the second set of articulated coordinate measuring machine bases and repeat steps S2 - S3 until the calibration and error compensation within the new measurement area are completed.

[0043] Preferably, the measurement accuracy of the laser tracker is not lower than ±0.01 mm, and the laser tracker supports the multi - target ball synchronous tracking function; the probe of the articulated coordinate measuring machine has six - degree - of - freedom adjustment ability, and the measurement repeatability error is less than ±0.005 mm.

[0044] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0045] 1. The present invention is provided with multiple measurement bases. When initially calibrating, the laser tracker is used to determine the positional relationship between the multiple measurement bases and the robot base coordinate. Move the articulated coordinate measuring machine to different positions to reach the positions of all work task calibration points and calibrate through the laser tracker. Then move the end of the industrial robot to the preset calibration point position. At this time, there is a deviation between the end position and the preset calibration point. Measure the coordinate of the end of the industrial robot through the articulated coordinate measuring machine, and thus obtain the end position error amount. The present invention solves the problem of limited measurement space of the articulated coordinate measuring machine, avoids the problem of installing numerous calibration parts required for calibration block calibration and the problem of additional errors introduced by human factors, reduces the calibration cost, improves the automation degree of the industrial robot operation, ensures the operation accuracy of the industrial robot during long - term processing, and the rapidity of re - calibration compensation after errors occur. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 is the layout orientation schematic diagram of the present invention;

[0047] Figure 2 is the schematic diagram of coordinate system establishment of the present invention.

[0048] The numbers in the figure represent:

[0049] 1. Industrial robot; 2. Laser tracker; 3. Target ball; 4. Articulated coordinate measuring machine base; 5. Articulated coordinate measuring machine. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0050] The following further elaborates the present invention in combination with the drawings and embodiments for the above - mentioned and other technical features and advantages of the present invention. However, the following embodiments are only the preferred embodiments of the present invention, not all of them.

[0051] Embodiment:

[0052] As Figure 1As shown in the figure, the present invention provides a calibration device for the working task points of an industrial robot, including an industrial robot 1, a laser tracker 2, a target ball 3, an articulated coordinate measuring machine base 4, and an articulated coordinate measuring machine 5;

[0053] The industrial robot 1 is fixedly installed at a designated position on the production line. A target ball 3 is configured at the end of the movable end of the industrial robot 1. The target ball 3 is used to reflect the laser signal emitted by the laser tracker 2 to obtain the position information of the end of the industrial robot 1 in real time;

[0054] The laser tracker 2 is arranged on the outer edge of the working area of the industrial robot 1, and the laser emission direction of the laser tracker 2 covers all the working task calibration points within the moving radius of the industrial robot 1;

[0055] At least three groups of articulated coordinate measuring machine bases 4 are evenly distributed along the inner edge of the working area of the industrial robot 1 and are on the same horizontal reference plane as the industrial robot 1. Each group of bases 4 is provided with a detachable mounting interface;

[0056] The articulated coordinate measuring machine 5 is connected to one group of articulated coordinate measuring machine bases 4 through the mounting interface, and a high-precision probe is configured at its end for contact measurement of the spatial coordinates of the working task calibration points;

[0057] The laser tracker 2 and the articulated coordinate measuring machine 5 are connected to the same control terminal through a data bus to achieve real-time synchronization and comparative analysis of the measurement data.

[0058] The control terminal is built-in with an error compensation algorithm, and the algorithm includes: a noise suppression module based on Kalman filtering for eliminating the instantaneous measurement error of the laser tracker 2, and an adaptive learning module based on neural network for predicting the long-term pose deviation caused by the joint wear of the industrial robot 1.

[0059] The measurement accuracy of the laser tracker 2 is not less than ±0.01 mm, and the laser tracker 2 supports the multi-target ball synchronous tracking function. The probe of the articulated coordinate measuring machine 5 has six-degree-of-freedom adjustment ability, and the measurement repeatability error is less than ±0.005 mm.

[0060] A calibration method for the calibration measurement device of the industrial robot working task points includes the following steps:

[0061] Step S1, initially calibrate the positions of the articulated coordinate measuring machine base 4 and the articulated coordinate measuring machine 5;

[0062] Step S11: Install the industrial robot 1 at the designated position, disperse no less than three articulated coordinate measuring machine bases 4 within the moving radius of the industrial robot 1. The articulated coordinate measuring machine bases 4 and the industrial robot 1 are on the same horizontal ground. Place the laser tracker 2 on the same horizontal ground, and keep a distance of at least 1 m between the laser tracker 2 and the three articulated coordinate measuring machine bases 4.

[0063] Step S12: Establish the first measurement coordinate system {x1, y1, z1} with the position of the laser tracker 2 as the origin.

[0064] Step S13: Measure through the laser tracker 2 and obtain the coordinates {x A , y A , z A} of the base coordinate of the industrial robot 1 in the first measurement coordinate system {x1, y1, z1}, and record it as and record it as the reference point.

[0065] Step S14: Measure through the laser tracker 2 and obtain the coordinate positions {x B1 , y B1 , z B1}, {x B2 , y B2 , z B2}, and {x B3 , y B3 , z B3} of each articulated coordinate measuring machine base 4 in the first measurement coordinate system {x1, y1, z1}, and record them as to form the base position database.

[0066] Step S15: Denote the position matrix of the base coordinate and the second measurement coordinate system as

[0067] The position transformation matrix of the base coordinate and the second measurement coordinate system is

[0068] Step S16: Record {x1, y1, z1}, {x A , y A , z A}, and {x B , y B , z B} respectively.

[0069] Step S17: Verify the consistency of the global coordinate system by fitting the reference point and the base position data through the least squares method. If the deviation exceeds the threshold, recalibrate.

[0070] In Step S1, the coordinates {xA , y A , z A} The position matrix of is denoted as

[0071] The coordinate position {x of each articulated coordinate measuring machine base 4 in the first measurement coordinate system {x1, y1, z1} B1 , y B1 , z B1}, x B2 , y B2 , z B2}, or {x B3 , y B3 , z B3} The position matrix of is denoted as

[0072] The position matrix of the base coordinate and the second measurement coordinate system is denoted as

[0073] The position transformation matrix of the base coordinate and the second measurement coordinate system is

[0074] Step S2, install the articulated coordinate measuring machine 5, calibrate the working task calibration points through the articulated coordinate measuring machine 5, and control the industrial robot 1 to carry the target ball 3 to run to the working task calibration points;

[0075] Step S21, establish the second measurement coordinate system {x 12 , y 12 , z 12} with the first set position of the articulated coordinate measuring machine as the origin, operate the articulated coordinate measuring machine 5 to sequentially adjust the end of the articulated coordinate measuring machine 5 to multiple working task preset calibration points, and obtain the task coordinate group T of each working task preset calibration point in the second measurement coordinate system {x 12 , y 12 , z 12} through the articulated coordinate measuring machine 5 i = {T1, T2,..., T n};

[0076] Step S22, obtain the joint angle θ that the industrial robot needs to rotate through the task coordinate group T i and the position transformation matrix of the base coordinate system and the second measurement coordinate system ; Bi ;

[0077]

[0078] Step S23, controlling the industrial robot 1 to drive the target ball 3 at the end of the movable end to move to each preset calibration point of the work task in sequence according to the joint angle, and pausing at each preset calibration point of the work task;

[0079] Step S24, the actual coordinate group N of the target sphere 3 at each preset calibration point of the work task is measured and obtained by the articulated coordinate measuring machine 5. i ={N1, N1, ..., N n};

[0080] Step S25: group the task coordinates into i With the actual coordinate group N i Compare, if the comparison result satisfies |T i -N i |≤∈, ∈ is the preset tolerance, then the calibration point is recorded as a valid calibration point; otherwise, step S3 is triggered to perform error compensation.

[0081] Step S3, compensating for the operation error of controlling the industrial robot 1 until the error approaches zero.

[0082] Step S31, according to the task coordinate group T of the articulated coordinate measuring machine 5 in the second measurement coordinate system i and the actual coordinate set N of the end position of the industrial robot 1 in the second coordinate system i Obtain the relative offset Δ;

[0083] Δ=T i -N i

[0084] Step S32, inputting the relative offset Δ obtained in step S31 into the control system of the industrial robot 1, generating an inverse kinematics compensation instruction, and adjusting the robot end trajectory;

[0085] Step S33, repeating steps S24-S26 until the offset Δ of all calibration points satisfies |Δ|≤∈;

[0086] Step S34, if there are still out-of-tolerance points after compensation, they are marked as abnormal points, and the theoretical coordinates of the points are remeasured by the articulated coordinate measuring machine 5 to eliminate mechanical structure deformation or environmental interference factors;

[0087] Step S35, moving the articulated coordinate measuring machine 5 to the second set of articulated coordinate measuring machine bases 4 and repeating steps S2-S3 until the calibration and error compensation in the new measurement area are completed.

[0088] The above are only the preferred embodiments of the present invention, which are illustrative rather than restrictive to the present invention. Those skilled in the art understand that many changes, modifications or even equivalents can be made within the spirit and scope defined by the claims of the present invention, but all of them will fall within the protection scope of the present invention.

Claims

1. A calibration device for the working task points of an industrial robot, characterized in that, It includes an industrial robot (1), a laser tracker (2), a target ball (3), an articulated coordinate measuring machine base (4) and an articulated coordinate measuring machine (5); The industrial robot (1) is fixedly installed at a designated position on the production line. The end of the movable end of the industrial robot (1) is equipped with the target ball (3), and the target ball (3) is used to reflect the laser signal emitted by the laser tracker (2) to obtain the position information of the end of the industrial robot (1) in real time; The laser tracker (2) is arranged on the outer edge of the operation area of the industrial robot (1), and the laser emission direction of the laser tracker (2) covers all the working task calibration points within the movement radius of the industrial robot (1); At least three groups of the articulated coordinate measuring machine bases (4) are evenly distributed along the inner edge of the operation area of the industrial robot (1) and are on the same horizontal reference plane as the industrial robot (1). Each group of bases (4) is provided with a detachable mounting interface; The articulated coordinate measuring machine (5) is connected to one group of the articulated coordinate measuring machine bases (4) through the mounting interface, and its end is equipped with a high-precision probe for contact measurement of the spatial coordinates of the working task calibration points; The laser tracker (2) and the articulated coordinate measuring machine (5) are connected to the same control terminal through a data bus to achieve real-time synchronization and comparative analysis of the measurement data.

2. The calibration device for the working task points of an industrial robot according to claim 1, characterized in that, The control terminal is built-in with an error compensation algorithm, and the algorithm includes: a noise suppression module based on Kalman filtering, which is used to eliminate the instantaneous measurement error of the laser tracker (2), and an adaptive learning module based on neural network, which is used to predict the long-term pose deviation caused by the joint wear of the industrial robot (1).

3. A calibration method for a calibration measurement device for the working task points of an industrial robot as described in claim 1, characterized in that, It includes the following steps: Step S1, initially calibrate the positions of the articulated coordinate measuring machine base (4) and the articulated coordinate measuring machine (5); Step S2, install the articulated coordinate measuring machine (5), calibrate the working task calibration points through the articulated coordinate measuring machine (5), and control the industrial robot (1) to carry the target ball (3) to run to the working task calibration points; Step S3, compensate for the running error of the controlled industrial robot (1) until the error approaches zero.

4. The calibration method of the calibration measurement device for the working task points of an industrial robot according to claim 3, characterized in that, The S1 includes: Step S11, install the industrial robot (1) at the designated position, disperse at least three groups of the articulated coordinate measuring machine bases (4) within the movement radius of the industrial machine (1), the articulated coordinate measuring machine bases (4) and the industrial machine (1) are on the same horizontal ground, set the laser tracker (2) on the same horizontal ground, and the laser tracker (2) and the three groups of the articulated coordinate measuring machine bases (4) are at least kept at a distance of more than 1m; Step S12, establish a first measurement coordinate system {x1, y1, z1} with the set point of the laser tracker (2) as the origin; Step S13, measure with a laser tracker (2) and obtain the coordinates {x A , y A , z A} of the base coordinate of the industrial robot (1) in the first measurement coordinate system {x1, y1, z1}, denoted as and record it as the reference reference point; Step S14, measure with a laser tracker (2) and obtain the coordinate positions {x B1 , y B1 , z B1} of each articulated coordinate measuring machine base (4) in the first measurement coordinate system {x1, y1, z1}, {x B2 , y B2 , z B2} and {x B3 , y B3 , z B3}, and record them as to form a base position database; Step S15, the position matrix of the base coordinate system and the second measurement coordinate system is denoted as The position transformation matrix between the base coordinate system and the second measurement coordinate system is Step S16, record {x1, y1, z1} and {x A , y A , z A} and {x B , y B , z B} respectively.

5. The calibration method of the calibration measurement device for the working task points of an industrial robot according to claim 4, characterized in that, The step S1 further includes: Step S17, fit the reference reference points and the base position data by the least squares method to verify the consistency of the global coordinate system. If the deviation exceeds the threshold, re-calibrate.

6. The calibration method of the calibration measurement device for the working task points of an industrial robot according to claim 3, characterized in that, The step S2 includes: Step S21: Establish a second measurement coordinate system {x 12 , y 12 , z 12} with the first set position of the articulated coordinate measuring machine as the origin. Operate the articulated coordinate measuring machine (5) to sequentially adjust the end of the articulated coordinate measuring machine (5) to multiple preset calibration points of the work tasks, and obtain the task coordinate group T 12 , y 12 , z 12} in the second measurement coordinate system for each preset calibration point of the work tasks. The task coordinate group T i = {T1, T2,..., T n}; Step S22, through the task coordinate group T i and the position transformation matrix of the base coordinate system and the second measurement coordinate system obtain the joint angle θ that the industrial robot needs to rotate Bi ; Step S23, controlling the industrial robot (1) to drive the target ball (3) at the end of the movable end to move to each preset calibration point of the work task in sequence according to the joint angle, and pausing at each preset calibration point of the work task; Step S24, measure and obtain the actual coordinate group N of the target ball (3) at the preset calibration points for each work task by means of an articulated coordinate measuring machine (5) i ={N1, N1,..., N n}; Step S25, compare the task coordinate group T i with the actual coordinate group N i and if the comparison result satisfies |T i - N i | ≤ ∈, where ∈ is a preset tolerance, record this calibration point as a valid calibration point; otherwise, trigger Step S3 for error compensation.

7. The calibration method of the calibration measurement device for the working task points of an industrial robot according to claim 3, characterized in that, The step S3 comprises: Step S31: Obtain the relative offset Δ based on the task coordinate group T of the articulated coordinate measuring machine (5) in the second measurement coordinate system i and the actual coordinate group N of the end position of the industrial robot 1 in the second coordinate system i ; Δ=T i -N i Step S32, inputting the relative offset Δ obtained in step S31 into the control system of the industrial robot (1), generating an inverse kinematics compensation instruction, and adjusting the robot end trajectory; Step S33, repeat steps S24-S26 until the offset Δ of all calibration points satisfies |Δ|≤∈.

8. The calibration method of the calibration measurement device for the working task points of an industrial robot as described in claim 7, characterized in that The step S3 further comprises: Step S34: if there are still out-of-tolerance points after compensation, they are marked as abnormal points, and the theoretical coordinates of the points are remeasured by an articulated coordinate measuring machine (5) to eliminate mechanical structure deformation or environmental interference factors.

9. The calibration method of the calibration measurement device for the working task points of an industrial robot according to claim 8, characterized in that The step S3 further comprises: Step S35, moving the articulated coordinate measuring machine (5) to the second set of articulated coordinate measuring machine bases (4) and repeating steps S2-S3 until the calibration and error compensation in the new measurement area are completed.

10. The calibration method of the calibration measurement device for the working task points of an industrial robot according to claim 1, characterized in that, The measurement accuracy of the laser tracker (2) is not less than ±0.01 mm, and the laser tracker (2) supports a multi-target ball synchronous tracking function; the probe of the articulated coordinate measuring machine (5) has a six-degree-of-freedom adjustment capability, and the measurement repeatability error is less than ±0.005 mm.

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