CN115122316A - Calibration method and calibration system for tool center point of robot - Google Patents
Calibration method and calibration system for tool center point of robot Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J11/00—Manipulators not otherwise provided for
- B25J11/005—Manipulators for mechanical processing tasks
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J9/00—Programme-controlled manipulators
- B25J9/16—Programme controls
- B25J9/1612—Programme controls characterised by the hand, wrist, grip control
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J9/00—Programme-controlled manipulators
- B25J9/16—Programme controls
- B25J9/1679—Programme controls characterised by the tasks executed
- B25J9/1692—Calibration of manipulator
Abstract
The application provides a calibration method of a tool center point of a robot, comprising the following steps: determining a robot base coordinate system, a flange plate coordinate system, an adapter coordinate system before deviation occurs, an adapter pin endpoint coordinate system before deviation occurs and a calibration sensor coordinate system; and acquiring a deviation endpoint-flange plate transformation matrix T for transforming the coordinate system of the endpoint of the adapter pin after the deviation to the coordinate system of the flange plate F AE1 (ii) a Wherein, when the tool is a pin type tool, the coordinate value of the central point of the tool is a deviation endpoint-flange transformation matrix T F AE1 The value of (d); and when the tool is a multi-finger tool, the coordinate value of the center point of the tool is a deviation adapter-flange transformation matrix T for transforming the adapter coordinate system after deviation to the flange coordinate system F A1 The numerical value of (c). The application also provides a calibration system for the tool center point of the robot. Calibration method and device of the present applicationThe calibration system can be used to calibrate both pin tools and multi-fingered tools, and can improve accuracy and reduce time.
Description
Technical Field
The present disclosure relates to the field of robot technology, and more particularly, to a method and a system for calibrating a tool center point of a robot.
Background
The robot performs a predetermined task by a tool attached to the end of the multi-joint arm, for example, a welding gun of a welding robot, a milling cutter, a jig of a transfer robot, or the like, according to a pre-programmed program. When programming a robot to complete a given task, it is necessary to set a Tool coordinate system to indicate the position coordinates of a working Point of a Tool, which is generally called a Tool Center Point (TCP). When the robot is in the initial state, the TCP is typically at the origin of the tool coordinate system. When the robot approaches the workpiece under program control, the TCP is actually brought closer to the workpiece. Therefore, TCP determines the actual working point of the tool of the robot. For a pin tool such as a welding gun or milling cutter, TCP is the end point at which the pin tool interacts with the workpiece, while for a multi-fingered tool (e.g., a carrier) having a plurality of fingers (i.e., jaws), TCP is the center point of the plurality of fingers.
In actual production, the TCP of the tool may be displaced due to wear, impact, deformation, or the like of the tool, and thus the actual working point of the tool will deviate from a predetermined position. If the original TCP data used by the control program is not calibrated and updated and the job is continued according to the original TCP data, the actions may not be in place and the product or service quality may be degraded. For this reason, the TCP of the robot usually needs to be calibrated frequently. Existing TCP calibration methods are generally only applicable to pin tools and TCP is determined by a four-point method or the like. This calibration method is time consuming and not very accurate. For multi-fingered (e.g., two-fingered) tools, the existing TCP calibration method is to consider each finger as a pinned tool, and perform separate calculation for each finger, and finally calculate the center point of multiple fingers. Therefore, the existing TCP calibration method cannot directly calculate the TCP of the multi-finger type clamp, and also has the defects of long time consumption and low precision.
Therefore, a calibration method and a calibration system capable of calibrating the TCP of the robot quickly and with high accuracy are required.
Disclosure of Invention
The present application is directed to overcome the disadvantages of the prior art, and provide a calibration method and a calibration system for a tool center point of a robot, which can complete calibration quickly and with high accuracy.
To this end, according to an aspect of the present application, there is provided a method of calibrating a tool center point of a robot including a robot base, a robot arm, a flange, an adapter pin, and a calibration sensor, the robot base, the robot arm, and the flange being sequentially arrangedPivotally coupled and fixedly coupled in sequence to said flange, said adapter and said adapter pin, wherein said calibration method comprises the steps of: determining a robot base coordinate system, a flange plate coordinate system, an adapter coordinate system before deviation occurs, an adapter pin endpoint coordinate system before deviation occurs and a calibration sensor coordinate system; and acquiring a deviation endpoint-flange plate transformation matrix T for transforming the adapter pin endpoint coordinate system after deviation to the flange plate coordinate system F AE1 (ii) a Wherein, when the tool of the robot is a pin-type tool, the adapter and the adapter pin correspond to the pin-type tool, and the coordinate value of the tool center point is the deviation endpoint-flange transformation matrix T F AE1 The value of (d); and when the tool of the robot is a multi-finger tool, the adapter corresponds to the multi-finger tool, and the coordinate value of the tool center point is a deviation adapter-flange transformation matrix T for transforming the adapter coordinate system after deviation to the flange coordinate system F A1 Wherein said offset adapter-flange transformation matrix T F A1 Is by said offset end-flange transformation matrix T F AE1 A deviation end point-adapter transformation matrix T for transforming from the adapter pin end point coordinate system before deviation to the adapter coordinate system A AE0 Is obtained by multiplication of the inverse matrix of (c).
According to another aspect of the application, a calibration system for a tool center point of a robot is provided, wherein the calibration system comprises a control unit configured to perform the above-mentioned calibration method.
The calibration method and the calibration system for the tool center point of the robot can be used for calibrating both a pin type tool and a multi-finger type tool, and can improve calibration precision and reduce calibration time.
Drawings
Exemplary embodiments of the present application will be described in detail below with reference to the attached drawings, it being understood that the following description of the embodiments is intended to be illustrative of the present application and not limiting of the scope of the present application, and in which:
fig. 1 is a schematic side view of a calibration system showing a tool center point of a robot according to an embodiment of the application;
FIG. 2 is a schematic top view showing the sensor shown in FIG. 1;
fig. 3A and 3B are schematic partial side views illustrating a robot before and after tool center points are biased according to an embodiment of the present application;
fig. 4A and 4B are schematic top and perspective views showing two circular motion trajectories of a tool center point of a robot according to an embodiment of the present application;
fig. 5A and 5B are schematic diagrams illustrating X, Y coordinate deviations and Z coordinate deviations of a tool center point of a robot according to an embodiment of the present application;
FIG. 6 is a schematic diagram showing the movement of a tool center point of a robot according to an embodiment of the present application; and
fig. 7 is a flowchart illustrating a method of calibrating a tool center point of a robot according to an embodiment of the present application.
Detailed Description
Preferred embodiments of the present application are described in detail below with reference to examples. However, it should be understood by those skilled in the art that these exemplary embodiments are not meant to limit the present application in any way. Furthermore, the features in the embodiments of the present application may be combined with each other without conflict. In the figures, other components or steps have been omitted for the sake of brevity, but this does not indicate that the method of calibration of the tool centre point of the robot of the present application may not comprise other steps, nor that the system of calibration of the tool centre point of the robot of the present application may comprise other components or modules.
As shown in fig. 1, the robot generally includes a robot base 10, a robot arm 11, a flange plate 20, an adaptor 30, an adaptor pin 40, and a calibration sensor 50, wherein the robot base 10, the robot arm 11, and the flange plate 20 are pivotally coupled in sequence, and the flange plate 20, the adaptor 30, and the adaptor pin 40 are fixedly coupled in sequence. Thus, the robot base coordinate system O can be determined RB And a flange plateCoordinate system O F Adapter coordinate system O before occurrence of deviation A0 (or O) G0 Corresponding to a multi-fingered tool), the adapter pin endpoint coordinate system O before deviation occurs AE0 And calibrating the sensor coordinate system O PS . It should be noted that the robot base coordinate system O RB Flange plate coordinate system O F And calibrating the sensor coordinate system O PS The relationship between them is relatively fixed. For example, the robot base 10 and the flange plate 20 are mechanically coupled by the robot hand 11, and the robot base 10 and the calibration sensor 50 are fixedly installed with respect to the ground. As shown in fig. 2, the calibration sensor 50 includes four sensors 51, e.g., laser sensors, for sensing the position of the adapter pin 40, and the sensors 51 determine a sensing plane 52. Of course, the calibration sensor 50 may also include other numbers of different sensors.
It is noted that for robots comprising pin-type tools, the adapter 30 and the adapter pin 40 together correspond to a pin-type tool, such as a welding gun or a milling cutter, whereas for robots comprising multi-fingered tools, the adapter 30 corresponds to a multi-fingered tool. Therefore, in actual production, the adapter coordinate system and the adapter pin end point coordinate system may deviate due to wear, collision, deformation, or the like of the tool, and the TCP of the tool may be offset. Therefore, the TCP of the robot needs to be calibrated frequently. As shown in fig. 3A and 3B, the robot tool center point is shown before and after deviation. In FIG. 3A, the adapter coordinate system before the deviation occurs is shown as O A0 (or O) G0 ) The coordinate system of the adapter pin end points before the deviation is shown as O AE0 (ii) a In FIG. 3B, the adapter coordinate system after the deviation is shown as O A1 (or O) G1 ) Offset adapter pin endpoint coordinate system O AE Is shown as O AE1 . The following description is mainly given in terms of O A0 And O A1 The adapter coordinate system is indicated as an example marker.
To this end, according to an embodiment, as shown in fig. 7, the calibration method for the tool center point of the robot proposed by the present application includes the following steps:
step S10: determining a robot base coordinate system O RB Flange coordinate system O F Adapter coordinate system O before occurrence of deviation A0 Before deviation occurs, the adapter pin end point coordinate system O AE0 And calibrating the sensor coordinate system O PS (ii) a And
step S20: obtaining the coordinate system O of the terminal point of the adapter pin after deviation AE1 Transformation to flange coordinate system O F Deviation end-flange transformation matrix T F AE1 ；
Wherein, when the tool of the robot is a pin type tool, the adaptor 30 and the adaptor pin 40 correspond to the pin type tool, and the coordinate value of the center point of the tool is a deviation end point-flange transformation matrix T F AE1 The value of (d); when the tool of the robot is a multi-fingered tool, the adapter 30 corresponds to the multi-fingered tool, and the coordinate value of the tool center point is the coordinate value of the adapter coordinate system O after deviation from the generated coordinate value A1 Transformation to flange coordinate system O F Deviation adapter-flange transformation matrix T F A1 Wherein the offset adapter-flange transformation matrix T F A1 By means of a deviation end-flange transformation matrix T F AE1 Coordinate system O of adapter pin end point before deviation AE0 Conversion to adapter coordinate system O before deviation occurs A0 Offset endpoint-adapter transformation matrix T A AE0 Is obtained by multiplication of the inverse matrix of (c).
In this way, the calibration method of the present application may be applied to the calibration of both pin tools and multi-fingered tools without the need to perform calculations for each finger of the multi-fingered tool. In addition, the calibration method of the application acquires the coordinate system O of the endpoint of the adapter pin after deviation occurs AE1 Transformation to flange coordinate system O F Deviation end-flange transformation matrix T F AE1 The TCP is calibrated, so that the precision can be improved, and the time can be shortened.
It should be noted that the transformation matrix between the a coordinate system and the B coordinate system usually employs T B A Are expressed in a form that is well defined in the art and will not be described in detail herein.
In the calibration method of the present application, the robot base coordinate system O RB One point on the base can be taken as an origin, a plane parallel to the ground is taken as an X-Y plane, and an axis vertical to the ground is taken as a Z axis; flange coordinate system O F The central point of the flange plate can be used as the original point, the plane of the flange plate is used as an X-Y plane, and the central axis of the flange plate is used as a Z axis; adapter coordinate system O before deviation A0 May be oriented with the midpoint of adapter 30 used to secure adapter pin 40 as the origin and the longitudinal axis of adapter pin 40 fixedly coupled to adapter 30 as the Y-axis; coordinate system O of adapter pin end point before deviation AE0 May be origin at an end point with the longitudinal axis of the adapter pin 40 being the Y-axis; calibrating the sensor coordinate system O PS May be based on the center point of the sensing plane 52 of the calibration sensor and have X, Y and Z axes, respectively, substantially parallel to the robot base coordinate system O FB X, Y and the Z axis. The above setting of each coordinate system is merely an example, and the present application is not limited thereto. As is known in the art, each coordinate system may be defined in different ways according to different coupling and movement manners, for example, a rectangular coordinate system, a cylindrical coordinate system, a spherical coordinate system, etc., and thus, this will not be described in detail herein.
As described above, the calibration method of the present application needs to obtain the offset endpoint-flange transformation matrix T F AE1 . According to an embodiment of the present application, the offset endpoint-flange transformation matrix T may be obtained by the following steps F AE1 ：
Step S21: obtaining the coordinate system O of the terminal point of the adapter pin before deviation AE0 Transformation to flange coordinate system O F Initial end-flange transformation matrix T F AE0 And from the calibration sensor coordinate system O PS Transforming to the robot base coordinate system O RB Sensor-base transformation matrix T RB PS A reference value of (d);
step S22: obtaining the adapter pin end point before deviation relative to the calibration sensor coordinate system O PS Initial spatial attitude value [ A 0 ,B 0 ,C 0 ]；
Step S23: obtaining deviation end point-flange transformation matrix T F AE1 Deviation of spatial attitude value [ A, B, C ]]；
Step S24: obtaining deviation end point-flange transformation matrix T F AE1 X, Y coordinate offset value of;
step S25: obtaining deviation end point-flange transformation matrix T F AE1 Z coordinate deviation value of (2);
step S26: obtaining deviation end point-flange transformation matrix T F AE1 The numerical value of (c).
However, the present application is not limited to the above-described steps. In the embodiment of the present application, the deviation spatial attitude value [ a, B, C ] represents the spatial attitude of the adapter pin endpoint (which corresponds directly or indirectly to the TCP of the pinned tool), typically represented by three angles of the rotation matrix, e.g., euler angles, however, the present application is not limited thereto, and may also be represented by a quaternion or the like, for example.
According to an embodiment of the present application, in the step S21, the initial end-flange transformation matrix T F AE0 Can be determined by a four-point method or given by the mechanical design of the robot, and the sensor-flange transformation matrix T RB PS The reference value of (c) can be determined by a three-point method. However, the above reference value may also be determined by other methods known in the art. Since the four-point method and the three-point method are widely used in the art as the positioning method, detailed description thereof will be omitted.
According to an embodiment of the present invention, in step S22, the terminal point of the adapter pin before deviation is obtained relative to the calibration sensor coordinate system O PS Initial spatial attitude value of [ A ] 0 ,B 0 ,C 0 ]The method can comprise the following steps:
(i) using a rotation axis
And rotation angle gamma 0 About the axis of rotation
Of the rotation matrix
So that the coordinate system O of the end point of the adapter pin before the deviation occurs AE0 And the calibration sensor coordinate system O PS I.e., the adapter pin 40 is perpendicular to the sensing plane 52 of the calibration sensor 50;
(ii) calculating the coordinate system O of the end point of the adapter pin before deviation AE0 Transformation to calibration sensor coordinate system O PS Initial endpoint-sensor rotation matrix R PS AE0 Wherein, in the step (A),
thus, an initial spatial attitude value [ A ] is obtained 0 ,B 0 ,C 0 ]Wherein R is RB PS Is from the calibration sensor coordinate system O PS Transforming to the robot base coordinate system O RB Of a rotation matrix R RB AE0 From the coordinate system O of the end point of the adapter pin before deviation occurs AE0 Transforming to the robot base coordinate system O RB The rotation matrix of (2).
According to an embodiment of the present application, in step S23, the offset endpoint-flange transformation matrix T F AE1 Deviation space attitude values of [ A, B, C ]]Can be obtained by the following steps:
(a) by making the adapter pin 40 perform two uniform circular movements at different heights, it is obtained that the adapter pin 40 is at different heights with respect to the calibration sensor coordinate system O PS The X, Y coordinate deviation value Δ x, Δ y of (a), comprising:
(i) make the adapter pin 40 at a certain speed V const_circ And radius r in the calibration sensor coordinate system O PS Making a first circular motion. For example, a first circular locus DC as shown in fig. 4A and 4B.
(ii) The adapter pin 40 is lowered a distance az as shown in fig. 4B.
(iii) Make the adapter pin 40 at speed V const_circ And radius r in the calibration sensor coordinate system O PS And the second circular motion is performed. For example, a second circular locus UC as shown in fig. 4A and 4B.
(iv) Respectively calculating the center of the first circular track and the center of the second circular track relative to the coordinate system O of the calibration sensor PS The X, Y coordinate deviation values Δ x, Δ y of the origin.
For example, as shown in FIG. 4A, a point P intersecting the X-axis is selected on the first circular trajectory DC and the second circular trajectory UC respectively d_x1 、P d_x2 、P d_y1 、P d_y2 And a point P intersecting the Y axis u_x1 、P u_x2 、P u_y1 、P u_y2 Then, for each circular trajectory, as shown in fig. 5A, Δ x, Δ y can be calculated by the following formulas:
wherein, theta x And theta y Respectively, the intersection point P of the circular locus and the X, Y axis x1 、P x2 、P y1 、P y2 An angle formed by a connecting line to the center of the circle and X, Y axes of the calibration sensor coordinate system is r, which is the radius of the circular track, so that X, Y coordinate deviation values Δ x and Δ y of the first circular track DC and the second circular track UC relative to X, Y axes of the calibration sensor coordinate system, that is, Δ x and Δ y respectively up 、Δx down 、Δy up 、Δy down 。
(b) Calculating adapter pin 40 relative to calibration sensor coordinate system O PS Angle of Z axis [ alpha, beta ]]And obtaining the adapter coordinate system O after the deviation occurs A1 Transformation to calibration sensor coordinate system O PS Offset adapter-sensor transformation matrix
As shown in FIG. 5B, if (Δ x) up -Δx down )*(Δy up -Δy down )>When equal to 0, then
α＝-atan2(Δy up -Δy down ,Δz)，
β＝atan2(Δx up -Δx down Δ z), otherwise
α＝atan2(Δy up -Δy down ,Δz)，
β＝-atan2(Δx up -Δx down ,Δz)。
Thus, by [ α, β,0 ]]The adapter coordinate system O after the deviation has occurred can be obtained A1 (or O) G1 Corresponding to a multi-fingered tool) to a calibration sensor coordinate system
(for multi-fingered tools, the transformation matrix can also be denoted T PS G1 )。
(c) By making the offset coordinate system O of the adapter pin end point AE1 And the calibration sensor coordinate system O PS Obtaining the coordinate system O of the terminal point of the adapter pin after deviation AE1 Transformation to calibration sensor coordinate system O PS Deviation endpoint-sensor rotation matrix R F AE1 Which comprises the following steps:
(i) using a rotation axis
And a rotation angle gamma acquired with respect to the rotation axis
Of the rotation matrix
(ii) Calculating deviation end-flange rotation matrix R F AE1 Wherein, in the step (A),
from this, the deviation space attitude values [ A, B, C ] are obtained]Wherein R is F A0 Is from the adapter coordinate system O before the deviation occurs A0 Transformation to flange coordinate system O F Of a rotation matrix R RB A0 Is from the adapter coordinate system O before the deviation occurs A0 Transformation to robot base coordinate system O RB Of a rotation matrix R RB A0 Is from the adapter coordinate system O before the deviation occurs A0 Transforming to the robot base coordinate system O RB Of a rotation matrix R A AE0 Is derived from the coordinate system O of the adapter pin end point before deviation occurs AE0 Conversion to adapter coordinate system O before deviation occurs A0 The rotation matrix of (2).
According to an embodiment of the present application, in the step S24, the offset end-flange transformation matrix T F AE1 The X, Y coordinate deviation values Δ X, Δ Y can be obtained by:
(a) updating deviation end-flange transformation matrix T F AE1 Deviation of spatial attitude value [ A, B, C ]]；
(b) The adapter pin 40 is acquired relative to the calibration sensor coordinate system O by making the adapter pin 40 perform a uniform circular motion PS X, Y coordinate deviation values Δ x, Δ y;
(c) obtaining adapter pin endpoint in calibration sensor coordinate system O PS Inner position deviation Δ P PS ＝[Δx,Δy,z F AE0 ,1]Wherein z is F AE0 The Z-axis height of the adapter pin end point relative to the flange before deviation occurs, so as to obtain the coordinate system O of the adapter pin end point on the flange F Inner position deviation Δ P F ＝P F AE0 +T F RB *T RB PS *ΔP PS In which P is F AE0 The end point of the adapter pin before deviation is in the flange coordinate system O F Inner position, T F RB Is from the robot base coordinate system O RB Transforming to flange coordinate system O F The transformation matrix of (2).
In this step, theAdapter pin end point in calibration sensor coordinate system O PS The X, Y coordinate deviation values Δ x, Δ y are calculated by aligning the adapter pins 40 in the calibration sensor coordinate system O in a manner similar to that in step S23 PS The inner part is obtained by moving at a constant speed along a circular track, and the details are not described herein.
According to an embodiment of the present application, in the step S25, the offset end-flange transformation matrix T F AE1 The Z-coordinate deviation value Δ Z of (a) may be obtained by:
(a) moving the adapter pin 40 linearly at a constant speed, Vconst _ dz, includes:
i) from a first set position P above the sensing plane 52 of the calibration sensor 50 1 To a second set position P below the sensing plane 52 of the calibration sensor 50 2 ；
ii) reverse movement to a first set position P 1 ；
iii) moving in reverse again to a second set position P 2 ；
Wherein a time is recorded each time an adapter pin end point passes the sensing plane 52 of the calibration sensor 50 to obtain a first time period t from the adapter pin end point passing the sensing plane 52 of the calibration sensor 50 a first time to a second time 1 And a second time period t from the adapter pin endpoint passing the sensing plane 52 of the calibrated sensor 50 a second time to the third time passing the sensing plane 52 of the calibrated sensor 50 2 。
In this step, the first set position P 1 And a second set position P 2 Can be preset in the robot, for example, in a first set position P 1 And a second set position P 2 Are respectively located on both sides of the sensing plane 52 of the calibration sensor 50 and are at the same distance from the sensing plane 52. For example, the first set position P 1 Preset xp9.z to 20.00 in the robot, the position of the sensing surface 52 is preset to xp10.z to xp9.z-20, and the second set position P 2 It is preset to xp11.z — xp9. z-40. It should be noted that only the Z coordinate value changes in these three positions, and the other positions and attitudes do not change.
(b) Obtaining a Z coordinate deviation value delta Z of the end point of the adapter pin, namely Vconst _ dz (t) 1 -t 2 )。
According to an embodiment of the present application, in step S26, a deviation endpoint-flange transformation matrix T is obtained F AE1 The value of (a) can be achieved by:
(a) updating adapter pin endpoints in calibration sensor coordinate system O PS Inner position shift:
ΔP PS ＝[ΔX,ΔY,ΔZ]；
(b) obtaining the end point of the adapter pin in the flange coordinate system O F Inner position shift:
ΔP F ＝P F AE0 +T F RB *T RB PS *ΔP PS ；
(c) using the position offset Δ P F Numerical update deviation endpoint-flange transformation matrix T in (1) F AE1 The numerical value of (c).
To this end, for a pin tool, the coordinate value of the center point of the tool is the deviation end point-flange transformation matrix T F AE1 Is [ X, Y, Z, A, B, C ]]A value; for a multi-fingered tool, the coordinate value of the center point of the tool is the offset adapter-flange transformation matrix T F A1 Is [ X, Y, Z, A, B, C ]]Value of, wherein T F A1 ＝T F AE1 *(T A AE0 ) -1 。
Thus, after the robot is calibrated to obtain a relevant reference value, if deviation occurs in the production process, the adapter (and the adapter pin) can be made to do uniform circular motion and uniform up-and-down motion by adopting the method of the application, so that the deviation value of the tool center point is determined. Whether a pin tool or a multi-fingered tool, the method of the present application can achieve calibration in a simple manner.
The method of the present application is described below in connection with specific exemplary embodiments.
As shown in fig. 7, the calibration method of the present application includes the following steps.
Step S10: determiningRobot base coordinate system O RB Flange plate coordinate system O F Adapter coordinate system O before occurrence of deviation A0 Coordinate system O of adapter pin end point before occurrence of deviation AE0 And calibrating the sensor coordinate system O PS As previously described.
Step S20: obtaining the coordinate system O of the terminal point of the adapter pin after deviation AE1 Transformation to flange coordinate system O F Deviation end-flange transformation matrix T F AE1 Which comprises the following steps.
Step S21: obtaining the coordinate system O of the end point of the adapter pin before deviation AE0 Transformation to flange coordinate system O F Initial end-flange transformation matrix T of F AE0 And from the calibration sensor coordinate system O PS Transforming to the robot base coordinate system O RB Sensor-base transformation matrix T RB PS The reference value of (1).
E.g. T RB PS The reference value of (A) is as follows:
| 0.99995 | 0.00838332 | -0.00548818 | 0.32729 |
| -0.00834245 | 0.999938 | 0.00742872 | 0.27175 |
| 0.00555012 | -0.00738256 | 0.999957 | 0.39022 |
| 0 | 0 | 0 | 1 |
T F AE0 the reference value of (A) is as follows:
| 0.999999 | 0.00122173 | -1.7058e-06 | -9e-05 |
| 0 | 0.00139622 | 0.999999 | -0.0004 |
| 0.00122173 | -0.999998 | 0.00139622 | 0.21098 |
| 0 | 0 | 0 | 1 |
step S22: obtaining the adapter pin end point before deviation relative to the calibration sensor coordinate system O PS Initial spatial attitude value of [ A ] 0 ,B 0 ,C 0 ]。
For example, the axis of rotation
The normal vector of (c) is:
| 0.233556 |
| -0.972306 |
| 0.00850515 |
rotation angle gamma 0 Comprises the following steps: 2.38325e-06 of the total weight of the product,
about the axis of rotation
Of the rotation matrix
Is given below as the coordinate system O of the adapter pin end point before deviation occurs AE0 Transforming to the robot base coordinate system O RB Is transformed by the transformation matrix T RB AE0 The partial values in (1) are shown in the double-line box in the following table:
then, the coordinate system O of the terminal point of the adapter pin before the deviation occurs is obtained AE0 Conversion to calibrationSensor coordinate system O PS Initial endpoint-sensor rotation matrix R PS AE0 Which is the adapter pin endpoint coordinate system O given below from before the deviation occurs AE0 Transformation to calibration sensor coordinate system O PS Of the transformation matrix T PS AE0 Some of the values in (1) are shown in the double-line box in the table below:
thus, the initial spatial attitude value [ A 0 ,B 0 ,C 0 ]Is given below as the coordinate system O of the adapter pin end point before deviation occurs AE0 Transformation to calibration sensor coordinate system O PS Is transformed by the transformation matrix T PS AE0 The partial values after RPY transformation are shown in the double-line box in the table below:
step S23: obtaining deviation end point-flange transformation matrix T F AE1 Deviation of spatial attitude value [ A, B, C ]]。
For example, after two circular movements, the adapter coordinate system O is obtained after the deviation has occurred A1 Transformation to calibration sensor coordinate system O PS Offset adapter-sensor transformation matrix
Comprises the following steps:
| 1 | -2.18507e-05 | -0.000624616 | 0 |
| 0 | 0.999389 | -0.0349613 | 0 |
| 0.000624998 | 0.0349612 | 0.999388 | 0 |
| 0 | 0 | 0 | 1 |
axis of rotation
The normal vector of (a) is:
| 0.999639 |
| -0.0262689 |
| 0.00567929 |
the rotation angle gamma is: 0.0349746,
about the axis of rotation
Of the rotation matrix
Is given below as the adapter pin endpoint coordinate system O after the deviation has occurred AE1 Transforming to the robot base coordinate system O RB Is transformed by the transformation matrix T RB AE1 The partial values in (1) are shown in the double-line box in the following table:
then, the coordinate system O of the terminal point of the adapter pin after the deviation occurs is obtained AE1 Coordinate system O transformed to flange plate sensor F Deviation end-flange rotation matrix R of F AE1 Which is the adapter pin endpoint coordinate system O given below from the occurrence of the deviation AE1 Transformation to flange coordinate system O F Is transformed by the transformation matrix T F AE1 The partial values in (1) are shown in the double-line box in the following table:
thus, the spatial attitude values [ A, B, C ] are deviated]Is given below as the adapter pin endpoint coordinate system O after the deviation has occurred AE1 Transformation to flange coordinate system O F Is transformed by the transformation matrix T F AE1 The partial values after RPY transformation are shown in the double-line box in the table below:
step S24: obtaining deviation end point-flange transformation matrix T F AE1 And X, Y coordinate deviation values Δ X, Δ Y.
For example, updating the offset endpoint-flange transformation matrix T F AE1 Deviation of spatial attitude value of[A,B,C]And making the adapter pin 40 do uniform circular motion to obtain the adapter pin 40 relative to the calibration sensor coordinate system O PS To obtain the deviation value Δ x, Δ y of the X, Y coordinate, thereby obtaining the terminal point of the adapter pin in the calibration sensor coordinate system O PS Inner position deviation Δ P PS Comprises the following steps:
| -9.67654e-06 |
| 0.00131438 |
| 0 |
thereby, the terminal point of the adapter pin in the flange coordinate system O is obtained F Inner position deviation Δ P F Comprises the following steps:
thus, X, Y coordinate deviations Δ X, Δ Y can be obtained, as shown in the double-line box in the above table.
Step S25: obtaining deviation end point-flange transformation matrix T F AE1 Z coordinate deviation value Δ Z.
For example, a first set position P is inputted 1 And a second set position P 2 The data for (c) are as follows:
| 1420 | 1436 | 1285 |
| 1417 | 1436 | 1283 |
Vconst_dz＝0.035m/s
ΔZ:0.16625mm
step S26: obtaining a deviation endpoint-flange transformation matrix T F AE1 The numerical value of (c).
For example, the adapter pin ends in the calibration sensor coordinate system O PS Inner position deviation Δ P PS Comprises the following steps:
| -9.67654e-06 |
| 0.00131438 |
| 0.00016625 |
thereby, the terminal point of the adapter pin in the flange coordinate system O is obtained F Inner position deviation Δ P F Comprises the following steps:
| 0.00122437 |
| -0.000409627 |
| 0.210982 |
thus, X, Y, Z coordinate deviations Δ X, Δ Y, Δ Z may be obtained, as shown in the above table.
Thus, a deviation endpoint-flange transformation matrix T can be obtained F AE1 The numerical value of (c):
| 78.5008 | -3.64199 | 200.457 | -3.07645 | -0.64228 | -90.1154 |
for pin tools, the coordinate value of the center point of the tool is the deviation end point-flange transformation matrix T F AE1 Is [ X, Y, Z, A, B, C ]]Value, and for a multi-fingered tool, the coordinate value of the tool center point is the offset adapter-flange transformation matrix T F A1 Is [ X, Y, Z, A, B, C ]]The values of, among others,
T F A1 ＝T F AE1 *(T A AE0 ) -1 。
therefore, after the offset of the tool occurs, the center point of the tool can be accurately determined by the calibration method, so that the processing and service quality can be improved.
It should be noted that in the above method examples, matrix and vector forms are used to represent the transformation or corresponding deviation between the respective coordinate systems, but the application is not limited thereto, and the above description is only illustrative. For example, each variable may be calculated and represented using different coordinate systems, transformation matrices, vectors, and the like, depending on the number of joints, motion patterns, constraints, position and attitude requirements, and the like of the robot.
According to another aspect of the present application, there is also provided a calibration system of a tool center point of a robot, the calibration system comprising a control unit 70, wherein the control unit 70 is configured to perform the calibration method described above.
The present application is described in detail above with reference to specific embodiments. However, the embodiments described above and shown in the drawings should be understood as illustrative and not limiting of the present application. It will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit of the application, and these changes and modifications do not depart from the scope of the application.
Claims (10)
1. A method for calibrating a tool center point of a robot, the robot comprising a robot base (10), a robot arm (11), a flange plate (20), an adapter (30), an adapter pin (40) and a calibration sensor (50), the robot base (10), the robot arm (11) and the flange plate (20) being pivotally coupled in sequence, and the flange plate (20), the adapter (30) and the adapter pin (40) being fixedly coupled in sequence, characterized in that the calibration method comprises the steps of:
determining a robot base coordinate system (O) RB ) Flange coordinate system (O) F ) Adapter coordinate system (O) before deviation occurs A0 ) And the coordinate system (O) of the adapter pin end point before the occurrence of the deviation AE0 ) And calibrating the sensor coordinate system (O) PS ) (ii) a And
obtaining the coordinate system (O) of the terminal point of the adapter pin after deviation AE1 ) Is transformed to the flange coordinate system (O) F ) Deviation end-flange transformation matrix T F AE1 ；
Wherein the adapter (30) and the adapter pin (40) correspond to the pin type tool when the tool of the robot is the pin type toolThe coordinate value of the tool center point is the deviation endpoint-flange plate transformation matrix T F AE1 The value of (d); and when the tool of the robot is a multi-fingered tool, the adapter (30) corresponds to the multi-fingered tool, and the coordinate value of the tool center point is an adapter coordinate system (O) deviated from the adapter coordinate system A1 ) Transformation to said flange coordinate system (O) F ) Deviation adapter-flange transformation matrix T F A1 Wherein said offset adapter-flange transformation matrix T F A1 Is obtained by transforming matrix T from said deviation end point to flange F AE1 From the coordinate system (O) of the end point of the adapter pin before said deviation occurs AE0 ) Transforming to said adapter coordinate system (O) before said deviation occurs A0 ) Offset endpoint-adapter transformation matrix T A AE0 Is obtained by multiplication of the inverse matrix of (c).
2. The calibration method according to claim 1, wherein the offset endpoint-flange transformation matrix T F AE1 Is obtained by the following steps:
(1) obtaining the coordinate system (O) of the terminal point of the adapter pin before the deviation occurs AE0 ) Transformation to said flange coordinate system (O) F ) Initial end-flange transformation matrix T F AE0 And from said calibration sensor coordinate system (O) PS ) Transforming to the robot base coordinate system (O) RB ) Sensor-base transformation matrix T RB PS A reference value of (d);
(2) obtaining the adapter pin endpoint before deviation from the calibration sensor coordinate system (O) PS ) Initial spatial attitude value [ A 0 ,B 0 ,C 0 ]；
(3) Obtaining the deviation end point-flange transformation matrix T F AE1 Deviation of spatial attitude value [ A, B, C ]]；
(4) Obtaining the deviation endpoint-flange plate transformation matrix T F AE1 X, Y coordinate deviation value of;
(5) obtaining the deviation end point-flange transformation matrix T F AE1 Z coordinate deviation value of (2);
(6) obtaining the deviation end point-flange transformation matrix T F AE1 The numerical value of (c).
3. The calibration method according to claim 2, wherein the initial endpoint-to-flange transformation matrix T F AE0 Is determined by a four-point method or is given by the mechanical design of the robot; and the sensor-flange transformation matrix T RB PS The reference value of (2) is determined by a three-point method.
4. Calibration method according to claim 2, characterized in that the adapter pin end points before deviation are acquired with respect to the calibration sensor coordinate system (O) PS ) Initial spatial attitude value of [ A ] 0 ,B 0 ,C 0 ]Which comprises the following steps:
(i) using a rotation axis
And the angle of rotation (gamma) 0 ) About said axis of rotation
Of the rotation matrix
So that said adapter pin end point coordinate system (O) before deviation occurs AE0 ) And the calibration sensor coordinate system (O) PS ) Is aligned with the Z axis;
(ii) calculating an adapter pin endpoint coordinate system (O) from said pre-deviation AE0 ) Transforming to the calibration sensor coordinate system (O) PS ) Initial endpoint-sensor rotation matrix R PS AE0 Wherein, in the step (A),
thereby obtaining an initial spatial attitude value [ A 0 ,B 0 ,C 0 ]，
Wherein R is RB PS Is from the calibration sensor coordinate system (O) PS ) Transforming to the robot base coordinate system (O) RB ) Of a rotation matrix R RB AE0 Is derived from the coordinate system (O) of the adapter pin end point before said deviation occurs AE0 ) Transforming to the robot base coordinate system (O) RB ) The rotation matrix of (2).
5. Calibration method according to claim 4, characterized in that the deviation endpoint-flange transformation matrix T F AE1 Deviation of spatial attitude value [ A, B, C ]]Is obtained by the following steps:
(a) acquiring the adapter pin (40) at different heights relative to the calibration sensor coordinate system (O) by making the adapter pin (40) perform two uniform circular motions at different heights PS ) The X, Y coordinate deviation value Δ x, Δ y of (a), comprising:
(i) causing the adapter pin (40) to rotate at a certain speed (V) const_circ ) And radius (r) in the calibration sensor coordinate system (O) PS ) Making a first circular motion;
(ii) -lowering the adapter pin (40) a certain distance (Δ z);
(iii) bringing the adapter pin (40) at the speed (V) const_circ ) And said radius (r) is in said calibration sensor coordinate system (O) PS ) Making a second circular motion;
(iv) calculating the center of the first circular motion track and the center of the second circular motion track respectively relative to the calibration sensor coordinate system (O) PS ) X, Y coordinate deviation values Δ x, Δ y of the origin of (1);
(b) calculating the adapter pin (40) relative to the calibration sensor coordinate system (O) PS ) Angle of Z axis [ alpha, beta ]]Obtaining the adapter coordinate system (O) after the deviation A1 ) Transforming to the calibration sensor coordinate system (O) PS ) Offset adapter-sensor transformation matrix
(c) By making said offset adapter pin end point coordinate system (O) AE1 ) And the calibration sensor coordinate system (O) PS ) Obtaining a coordinate system (O) of the terminal point of the adapter pin from the offset AE1 ) Transforming to the calibration sensor coordinate system (O) PS ) Deviation endpoint-sensor rotation matrix (R) F AE1 ) Which comprises the following steps:
(i) using a rotation axis
And a rotation angle (γ) obtained with respect to said rotation axis
Of the rotation matrix
(ii) Calculating the deviation end point-flange rotation matrix R F AE1 Wherein R is F AE1 ＝
Thereby obtaining said deviation spatial attitude value [ A, B, C]Wherein R is F A0 Is derived from the adapter coordinate system (O) before said deviation occurs A0 ) Transformation to said flange coordinate system (O) F ) Of a rotation matrix R RB A0 Is derived from the adapter coordinate system (O) before said deviation occurs A0 ) Transforming to the robot base coordinate system (O) RB ) Of a rotation matrix R RB A0 Is derived from the adapter coordinate system (O) before said deviation occurs A0 ) Transforming to the robot base coordinate system (O) RB ) Of a rotation matrix R A AE Is derived from the coordinate system (O) of the adapter pin end point before said deviation occurs AE0 ) Conversion to before said deviation occursOrchestrator coordinate system (O) A0 ) The rotation matrix of (2).
6. The calibration method according to claim 5, wherein the offset endpoint-flange transformation matrix T F AE1 The X, Y coordinate deviation value is obtained by the following steps:
(a) updating the offset endpoint-flange transformation matrix T F AE1 Deviation of spatial attitude value [ A, B, C ]]；
(b) Acquiring the adapter pin (40) relative to the calibration sensor coordinate system (O) by making the adapter pin (40) perform a uniform circular motion PS ) X, Y coordinate deviation values Δ x, Δ y;
(c) obtaining the adapter pin endpoint in the calibration sensor coordinate system (O) PS ) Inner position deviation Δ P PS ＝[Δx,Δy,z F AE0 ,1]Wherein z is F AE0 Is the Z-axis height of the adapter pin end point with respect to the flange plate, thereby obtaining the adapter pin end point in the flange plate coordinate system (O) F ) Inner position deviation Δ P F ＝P F AE0 +T F RB *T RB PS *ΔP PS In which P is F AE0 The adapter pin end points before deviation are in the flange coordinate system (O) F ) Inner position, T F RB Is from the robot base coordinate system (O) RB ) Is transformed to the flange coordinate system (O) F ) Thereby obtaining said offset end-flange transform matrix T F AE1 X, Y coordinate offset value.
7. The calibration method according to claim 6, wherein the offset endpoint-flange transformation matrix T F AE1 The Z coordinate deviation value is obtained by the following steps:
(a) linearly moving the adapter pin (40) at a constant speed, Vconst _ dz, comprising:
i) sensing from a sensor located at the calibration sensor (50)A first set position (P) above the plane (52) 1 ) To a second set position (P) below the sensing plane (52) of the calibration sensor (50) 2 )；
ii) moving in reverse to the first set position (P) 1 )；
iii) moving back again to the second set position (P) 2 )；
Wherein a time is recorded each time the adapter pin end point passes the sensing plane (52) of the calibration sensor (50) to obtain a first time period t from the adapter pin end point passing the sensing plane (52) of the calibration sensor (50) a first time to a second time 1 And a second time period t from the adapter pin endpoint passing the sensing plane (52) of the calibration sensor (50) a second time to a third time passing the sensing plane (52) of the calibration sensor (50) 2 ；
(b) Acquiring a Z coordinate deviation value delta Z of the end point of the adapter pin, namely Vconst _ dz (t) 1 -t 2 )。
8. Calibration method according to claim 7, characterized in that the deviation endpoint-flange transformation matrix T is obtained F AE1 The numerical value of (A) is realized by the following steps:
(a) updating the adapter pin endpoint in the calibration sensor coordinate system (O) PS ) Inner position deviation Δ P PS ＝[ΔX,ΔY,ΔZ,1]；
(b) Obtaining the coordinates (O) of the adapter pin end points in the flange plate coordinate system F ) Inner position deviation Δ P F ＝P F AE0 +T F RB *T RB PS *ΔP PS 。
(c) Using the position offset Δ P F Updating the deviation endpoint-flange transformation matrix T by the numerical value in F AE1 The numerical value of (c).
9. The calibration method according to claim 8, wherein for a pin tool, the tool centerThe coordinate value of the point is the deviation endpoint-flange transformation matrix T F AE1 Is [ X, Y, Z, A, B, C ]]A value; for a multi-fingered tool, the coordinate value of the center point of the tool is the offset adapter-flange transformation matrix T F A1 Is [ X, Y, Z, A, B, C ]]The values of, among others,
T F A1 ＝T F AE1 *(T A AE0 ) -1 。
10. calibration system of a tool center point of a robot, characterized in that the calibration system comprises a control unit (70), the control unit (70) being configured to perform a calibration method according to any of claims 1-9.
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