US-20260124755-A1 - POSITION ADJUSTMENT METHOD OF MANIPULATOR

Abstract

A position adjustment method of a manipulator in a machining system includes: positioning the manipulator such that a reference object having a specific shape gripped by or secured to an end effector is positioned at a workpiece grasping preparation position; mounting a contact-type sensor on a tool rest, moving the tool rest such that the contact-type sensor is brought into contact with the reference object, obtaining positions of translational drive axes at time points, and calculating contact point positions from the obtained translational drive axis positions; calculating an error of a position and/or a posture of the reference object gripped by or secured to the end effector from a plurality of the contact point positions and a command value; and compensating the position and/or the posture of the end effector so as to cancel the error of the position and/or the posture of the reference object.

Inventors

• Tetsuya Matsushita
• Ryo Nakanishi

Assignees

• OKUMA CORPORATION

Dates

Publication Date

20260507

Application Date

20250909

Priority Date

20240920

Claims (18)

1. 1 . A position adjustment method of a manipulator in a machining system, wherein the machining system includes: a machine tool including a chuck configured to grasp a workpiece, a tool rest on which a tool is mountable, and three or more translational drive axes that enable a translational motion of the tool rest; and a manipulator having an end effector configured to grip the workpiece and a plurality of joint driving axes, wherein the position adjustment method of the manipulator adjusts a position and/or a posture of the end effector at a workpiece grasping position at which the workpiece gripped by the end effector is grasped by the chuck, and the position adjustment method comprises: a first reference object positioning step of positioning the manipulator such that a reference object having a specific shape gripped by or secured to the end effector is positioned at a workpiece grasping preparation position near the workpiece grasping position; a first reference object position measuring step of (i) mounting a contact-type sensor on the tool rest, (ii) moving the tool rest such that the contact-type sensor is brought into contact with the reference object positioned at the first reference object positioning step, (iii) obtaining positions of the translational drive axes when the contact-type sensor detects contacts, and (iv) calculating contact point positions from the obtained translational drive axis positions; a first reference object position error calculating step of calculating an error of a position and/or a posture of the reference object gripped by or secured to the end effector from a plurality of the contact point positions obtained by executing the first reference object position measuring step for a plurality of positions of the reference object and a command value of the position and posture of the end effector at the first reference object positioning step; a first manipulator position compensating step of compensating the position and/or the posture of the end effector so as to cancel the error of the position and/or the posture of the reference object calculated at the first reference object position error calculating step.
2. 2 . The position adjustment method of the manipulator according to claim 1 , further comprising: a second reference object positioning step of positioning the manipulator such that the reference object gripped by or secured to the end effector has a position and/or a posture different from that at the first reference object positioning step; a second reference object position measuring step of (i) moving the tool rest such that the contact-type sensor mounted on the tool rest is brought into contact with the reference object gripped by or secured to the end effector positioned at the second reference object positioning step, (ii) obtaining positions of the translational drive axes when the contact-type sensor detects contacts, and (iii) calculating contact point positions from the obtained positions of the translational drive axes; and a first reference object dimension measuring step of calculating dimensions of the reference object from a plurality of the contact point positions obtained by executing the second reference object position measuring step for a plurality of positions of the reference object, wherein in the first reference object position error calculating step, the error of the position and/or the posture of the reference object gripped by or secured to the end effector is calculated further using the reference object dimensions calculated at the first reference object dimension measuring step.
3. 3 . The position adjustment method of the manipulator according to claim 1 , wherein when the error of the position and/or the posture of the reference object calculated at the first reference object position error calculating step is equal to or more than a predetermined threshold, the first reference object positioning step to the first manipulator position compensating step are repeated.
4. 4 . A position adjustment method of a manipulator in a machining system, wherein the machining system includes: a machine tool including a chuck configured to grasp a workpiece, a tool rest on which a tool is mountable, and three or more translational drive axes that enable a translational motion of the tool rest; and a manipulator having an end effector configured to grip the workpiece and a plurality of joint driving axes, wherein the position adjustment method of the manipulator adjusts a position and/or a posture of the end effector at a workpiece grasping position at which the workpiece gripped by the end effector is grasped by the chuck, and the position adjustment method comprises: a first confirmation positioning step of positioning the manipulator such that a reference object having a specific shape gripped by or secured to the end effector is positioned at a preset workpiece confirmation position; a first confirmation measurement step of (i) mounting a contact-type sensor on the tool rest, (ii) moving the tool rest such that the contact-type sensor is brought into contact with the reference object positioned at the first confirmation positioning step, (iii) obtaining positions of the translational drive axes when the contact-type sensor detects contacts, and (iv) calculating contact point positions from the obtained positions of the translational drive axes; a first confirmation position calculating step of calculating a position and/or a posture of the reference object gripped by or secured to the end effector from a plurality of the contact point positions obtained by executing the first confirmation measurement step for a plurality of positions of the reference object; a first position change amount calculating step of calculating an amount of change of the position and/or the posture of the reference object from a calculated value of the position and/or the posture of the reference object calculated at the first confirmation position calculating step and a recorded value of the position and/or the posture of the reference object measured in advance and recorded; and a first confirmation position compensating step of compensating the position and/or the posture of the end effector so as to cancel the amount of change calculated at the first position change amount calculating step.
5. 5 . The position adjustment method of the manipulator according to claim 4 , further comprising: a second confirmation positioning step of positioning the manipulator such that the reference object gripped by or secured to the end effector has a position and/or a posture different from that at the first confirmation positioning step; a second confirmation position measuring step of (i) moving the tool rest such that the contact-type sensor mounted on the tool rest is brought into contact with the reference object gripped by or secured to the end effector positioned at the second confirmation positioning step, (ii) obtaining positions of the translational drive axes when the contact-type sensor detects contacts, and (iii) calculating contact point positions from the obtained positions of the translational drive axes; and a second reference object dimension measuring step of calculating dimensions of the reference object from a plurality of the contact point positions obtained by executing the second confirmation position measuring step for a plurality of positions of the reference object, wherein in the first confirmation position calculating step, the position and/or the posture of the reference object gripped by or secured to the end effector is calculated further using the reference object dimensions measured at the second reference object dimension measuring step.
6. 6 . The position adjustment method according to claim 4 , wherein when the amount of change calculated at the first position change amount calculating step is equal to or more than a predetermined threshold, the first confirmation positioning step to the first confirmation position compensating step are repeated.
7. 7 . A position adjustment method of a manipulator in a machining system, wherein the machining system includes: a machine tool including a chuck configured to grasp a workpiece, a tool rest on which a tool is mountable, and a translational drive axis for enabling the tool rest to perform a translational motion, the tool rest having two or less degree of freedom of the translational motion; and a manipulator having an end effector configured to grip the workpiece and a plurality of joint driving axes, wherein the position adjustment method of the manipulator adjusts a position and/or a posture of the end effector at a workpiece grasping position at which the workpiece gripped by the end effector is grasped by the chuck, and the position adjustment method comprises: a third reference object positioning step of positioning the manipulator such that the reference object having a specific shape gripped by or secured to the end effector is positioned at a workpiece grasping preparation position near the workpiece grasping position; a first machine tool position measuring step of (i) moving the tool rest such that a contact-type sensor mounted on the tool rest is brought into contact with the reference object positioned at the third reference object positioning step, (ii) obtaining a position of the translational drive axis when the contact-type sensor detects a contact, and (iii) calculating a machine tool contact point position from the obtained position of the translational drive axis; a first sensor positioning step of positioning the tool rest such that the contact-type sensor mounted on the tool rest is positioned at the workpiece grasping preparation position; a first manipulator position measuring step of (i) moving the end effector such that the reference object gripped by or secured to the end effector is brought into contact with the contact-type sensor positioned at the first sensor positioning step, (ii) obtaining positions of the joint driving axes when the contact-type sensor detects contacts, and (iii) calculating manipulator contact point positions from the obtained positions of the joint driving axes; a second reference object position error calculating step of calculating an error of a position and/or a posture of the reference object gripped by or secured to the end effector at the workpiece grasping preparation position from a command value of the position and posture of the end effector at the third reference object positioning step, a plurality of the machine tool contact point positions obtained by executing the first machine tool position measuring step for a plurality of positions of the reference object, a command value of a plurality of positions of the tool rest when the first sensor positioning step is executed at a plurality of positions of the workpiece grasping preparation position, and a plurality of the manipulator contact point positions obtained by executing the first manipulator position measuring step at the plurality of positions of the workpiece grasping preparation positions; and a second manipulator position compensating step of compensating the position and/or the posture of the end effector so as to cancel the error of the position and/or the posture of the reference object calculated at the second reference object position error calculating step.
8. 8 . The position adjustment method of the manipulator according to claim 7 , further comprising: a fourth reference object positioning step of positioning the manipulator such that the reference object gripped by or secured to the end effector has a position and/or a posture different from that at the third reference object positioning step; a second machine tool position measuring step of (i) moving the tool rest such that the contact-type sensor mounted on the tool rest is brought into contact with the reference object positioned at the fourth reference object positioning step, (ii) obtaining a position of the translational drive axis when the contact-type sensor detects a contact, and (iii) calculating machine tool contact point positions from the obtained position of the translational drive axis; and a third reference object dimension measuring step of calculating dimensions of the reference object from a plurality of the machine tool contact point positions obtained by executing the second machine tool position measuring step for a plurality of positions of the reference object, wherein in the second reference object position error calculating step, the error of the position and/or the posture of the reference object gripped by or secured to the end effector is calculated further using the reference object dimensions obtained at the third reference object dimension measuring step.
9. 9 . The position adjustment method of the manipulator according to claim 7 , wherein when the error of the position and/or the posture of the reference object calculated at the second reference object position error calculating step is equal to or more than a predetermined threshold, the third reference object positioning step to the second manipulator position compensating step are repeated.
10. 10 . A position adjustment method of a manipulator in a machining system, wherein the machining system comprising: a machine tool including a chuck configured to grasp a workpiece, a tool rest on which a tool is mountable, and a translational drive axis for enabling the tool rest to perform a translational motion, the tool rest having two or less degree of freedom of the translational motion; and a manipulator having an end effector configured to grip the workpiece and a plurality of joint driving axes, wherein the position adjustment method of the manipulator adjusts a position and/or a posture of the end effector at a workpiece grasping position at which the workpiece gripped by the end effector is grasped by the chuck, and the position adjustment method comprises: a third confirmation positioning step of positioning the manipulator such that the reference object having a specific shape gripped by or secured to the end effector is positioned at a workpiece confirmation position different from the workpiece grasping position; a third machine tool position measuring step of (i) moving the tool rest such that a contact-type sensor mounted on the tool rest is brought into contact with the reference object positioned at the third confirmation positioning step, (ii) obtaining a position of the translational drive axis when the contact-type sensor detects a contact, and (iii) calculating a machine tool contact point position from the obtained position of the translational drive axis; a second sensor positioning step of positioning the tool rest such that the contact-type sensor mounted on the tool rest is positioned at the workpiece confirmation position; a second manipulator position measuring step of (i) moving the end effector such that the reference object gripped by or secured to the end effector is brought into contact with the contact-type sensor positioned at the second sensor positioning step, (ii) obtaining positions of the joint driving axes when the contact-type sensor detects contacts, and (iii) calculating manipulator contact point positions from the obtained positions of the joint driving axes; a second confirmation position calculating step of calculating a position and/or a posture of the reference object gripped by or secured to the end effector at the workpiece confirmation position from a command value of the position and posture of the end effector at the third confirmation positioning step, a plurality of the machine tool contact point positions obtained by executing the third machine tool position measuring step for a plurality of positions of the reference object, a command value of a plurality of positions of the tool rest when the second sensor positioning step is executed at a plurality of positions of the workpiece confirmation position, and a plurality of the manipulator contact point positions obtained by executing the second manipulator position measuring step at a plurality of positions of the workpiece confirmation positions; a second position change amount calculating step of calculating an amount of change in the position and/or the posture of the reference object from a calculated value of the position and/or the posture of the reference object calculated at the second confirmation position calculating step and a recorded value of the position and/or the posture of the reference object measured in advance and recorded; and a second confirmation position compensating step of compensating the position and/or the posture of the end effector so as to cancel the amount of change calculated at the second position change amount calculating step.
11. 11 . The position adjustment method of the manipulator according to claim 10 , wherein when the amount of change in the position and/or the posture of the reference object calculated at the second position change amount calculating step is equal to or more than a predetermined threshold, the third confirmation positioning step to the second confirmation position compensating step are repeated.
12. 12 . A position adjustment method of a manipulator in a machining system, wherein the machining system includes: a machine tool including a chuck configured to grasp a workpiece, a tool rest on which a tool is mountable, and a translational drive axis for enabling the tool rest to perform a translational motion; and a manipulator having an end effector configured to grip the workpiece and a plurality of joint driving axes, wherein the position adjustment method of the manipulator adjusts a position and/or a posture of the end effector at a workpiece grasping position at which the workpiece gripped by the end effector is grasped by the chuck, and the position adjustment method comprises: a third sensor positioning step of positioning the tool rest such that a contact-type sensor mounted on the tool rest is positioned at a workpiece grasping preparation position near the workpiece grasping position; a third manipulator position measuring step of (i) moving the end effector such that the reference object gripped by or secured to the end effector is brought into contact with the contact-type sensor positioned at the third sensor positioning step, (ii) obtaining a position of the joint driving axis when the contact-type sensor detects a contact, and (iii) calculating a contact point position from the obtained position of the joint driving axis; a third reference object position error calculating step of calculating an error of a position and/or a posture of the reference object gripped by or secured to the end effector at the workpiece grasping preparation position from command values of a plurality of positions of the tool rest when the third sensor positioning step is executed for a plurality of positions of the workpiece grasping preparation position and a plurality of the contact point positions obtained by executing the third manipulator position measuring step at a plurality of positions of the workpiece grasping preparation position; a third manipulator position compensating step of compensating the position and/or the posture of the end effector so as to cancel the error of the position and/or the posture of the reference object calculated at the third reference object position error calculating step.
13. 13 . The position adjustment method of the manipulator according to claim 12 , further comprising: a fourth sensor positioning step of positioning the tool rest such that the contact-type sensor mounted on the tool rest is positioned at a dimension measurement position different from the workpiece grasping preparation position; a fourth manipulator position measuring step of (i) moving the end effector such that the reference object gripped by or secured to the end effector is brought into contact with the contact-type sensor positioned at the fourth sensor positioning step, (ii) obtaining a position of the joint driving axis when the contact-type sensor detects a contact, and (iii) calculating a contact point position from the obtained position of the joint driving axis; and a fifth reference object dimension measuring step of calculating dimensions of the reference object from a plurality of the contact point positions obtained by executing the fourth manipulator position measuring step for a plurality of positions of the reference object, wherein in the third reference object position error calculating step, the error of the position and/or the posture of the reference object gripped by or secured to the end effector is calculated further using the reference object dimensions obtained at the fifth reference object dimension measuring step.
14. 14 . The position adjustment method of the manipulator according to claim 12 , wherein when the error of the position and/or the posture of the reference object calculated at the third reference object position error calculating step is equal to or more than a predetermined threshold, the third sensor positioning step to the third manipulator position compensating step are repeated.
15. 15 . The position adjustment method of the manipulator according to claim 12 , wherein the tool rest has two or less degree of freedom of the translational motion.
16. 16 . A position adjustment method of a manipulator in a machining system, wherein the machining system includes: a machine tool including a chuck configured to grasp a workpiece, a tool rest on which a tool is mountable, and a translational drive axis for enabling the tool rest to perform a translational motion; and a manipulator having an end effector configured to grip the workpiece and a plurality of joint driving axes, wherein the position adjustment method of the manipulator adjusts a position and/or a posture of the end effector at a workpiece grasping position at which the workpiece gripped by the end effector is grasped by the chuck, and the position adjustment method comprises: a fifth sensor positioning step of positioning the tool rest such that a contact-type sensor mounted on the tool rest is positioned at a workpiece confirmation position different from the workpiece grasping position; a fifth manipulator position measuring step of (i) moving the end effector such that the reference object gripped by or secured to the end effector is brought into contact with the contact-type sensor positioned at the fifth sensor positioning step, (ii) obtaining a position of the joint driving axis when the contact-type sensor detects a contact, and (iii) calculating a contact point position from the obtained position of the joint driving axis; a third confirmation position calculating step of calculating a position and/or a posture of the reference object gripped by the end effector from command values of a plurality of positions of the tool rest when the fifth sensor positioning step is executed for a plurality of positions of the workpiece confirmation position and a plurality of the contact point positions obtained by executing the fifth manipulator position measuring step at a plurality of positions of the workpiece confirmation position; a third position change amount calculating step of calculating an amount of change in the position and/or the posture of the reference object from a calculated value of the position and/or the posture of the reference object calculated at the third confirmation position calculating step and a recorded value of the position and/or the posture of the reference object measured in advance and recorded; and a third confirmation position compensating step of compensating the position and/or the posture of the end effector so as to cancel the amount of change calculated at the third position change amount calculating step.
17. 17 . The position adjustment method of the manipulator according to claim 16 , wherein when the amount of change in the position and/or the posture of the reference object calculated at the third position change amount calculating step is equal to or more than a predetermined threshold, the fifth sensor positioning step to the third confirmation position compensating step are repeated.
18. 18 . The position adjustment method of the manipulator according to claim 16 , wherein the tool rest has two or less degree of freedom of the translational motion.

Description

CROSS REFERENCE TO RELATED APPLICATION This application claims the benefit of Japanese Patent Application Number 2024-164168 filed on Sep. 20, 2024, the entirety of which is incorporated by reference. FIELD OF THE INVENTION The disclosure relates to a position adjustment method of a manipulator for adjusting a carry-in position when a workpiece is carried into and out of a machine tool by a manipulator using an industrial robot. BACKGROUND OF THE INVENTION In an automated manufacturing system constituted of a facility, such as an industrial robot and a machine tool including a manipulator, the industrial robot uses the manipulator to automatically perform a sequence of operations. The sequence of operations is of picking up a material of a workpiece from a workpiece stocker that is a storage area of the workpiece and carrying the material into the machine tool, and, after the machine tool machines the workpiece, carrying the machined workpiece out and returning the workpiece to the workpiece stocker. The operation by the manipulator of the industrial robot is instructed by a teaching work of a position and posture of an end effector at each position on a motion trajectory. The teaching work is performed by positioning the manipulator at a desired position using an operation pendant, and recording a current position of each axis of the manipulator then. In position teaching in which a workpiece is carried into a machine tool and a grasping portion of the machine tool is caused to grasp the workpiece, when it is necessary to keep the grasping position in a predetermined tolerance, for example, at the grasping position and a preparation position in its vicinity, the position and posture of the workpiece are finely adjusted. One method for executing the fine adjustment is a fine adjustment of a position and posture of the manipulator. However, the fine adjustment is often executed with a visual observation, which is an operation that requires significant time and effort. In addition, a relative position between the machine tool and the industrial robot slightly changes due to secular change of a surrounding environment, such as a floor base, which shifts a carry-in position. Accordingly, re-teaching is periodically required, and time and effort are required each time. Therefore, in order to efficiently execute teaching, a unit to measure a position and posture between the workpiece and the machine tool is important. JP 2022-522131 A discloses a method that enables a measurement of a position and posture of a workpiece by measuring a workpiece gripped by a manipulator using two sensor units disposed in a peripheral area of a chuck that grasps the workpiece in a machine tool, and measuring the workpiece by rotating the sensor units about the chuck, and adjusts the position and posture of the workpiece based on a measurement result. JP 6785931 B discloses a method that preliminarily records a reference image by photographing a marker disposed in a machine tool using a camera attached on a robot while a manipulator is in the machine tool, photographs the marker again when the manipulator enters the machine tool again, and estimates an attitude error amount of the manipulator from a difference between the photographed image and the reference image. The method in JP 2022-522131 A has an issue that a special sensor unit disposed in the peripheral area of the chuck is necessary. Removal/mounting of the sensor unit is necessary before and after teaching, which basically requires a human intervention, and therefore, there also is an issue that an automatic measurement is not possible. On the other hand, the method in JP 6785931 B has an issue that a relatively expensive camera is necessary. Furthermore, photographing the marker using the camera does not allow a position measurement with high accuracy, which is not applicable when a position tolerance necessary for grasping the workpiece in the machine tool is small. There also is an issue that a workpiece grasping position fails to be precisely measured because a marker photographing position and the workpiece grasping position are different. Therefore, it is an object of the disclosure to provide a position adjustment method of a manipulator that measures a position and posture of a workpiece near a carry-in position when the workpiece gripped by the manipulator of an industrial robot is carried into a machine tool using a contact-type sensor mounted on a tool main spindle of the machine tool, and adjusts a position and posture of an end effector of the manipulator based on a measurement result. SUMMARY OF THE INVENTION In order to solve the above-described issues, a first configuration of the present disclosure is a position adjustment method of a manipulator in a machining system. The machining system includes: a machine tool including a chuck configured to grasp a workpiece, a tool rest on which a tool is mountable, and three or more translational drive axes that ena