How to adjust the position of the manipulator

Abstract

This invention provides a manipulator position adjustment method that measures the position and orientation of a workpiece near the loading point when the workpiece gripped by the manipulator is loaded into the machine tool using a contact-type sensor attached to the tool spindle of the machine tool, and adjusts the position and orientation of the manipulator's end effector based on the measurement results. [Solution] The manipulator 10's end effector 11 grips a reference workpiece 13, and the touch probe 8 mounted on the tool base 2A is moved to the tool base 2A or the end effector 11, causing the touch probe 8 to come into contact with the reference workpiece at multiple points. The position of the joint drive axis of the manipulator 10 at the time of contact detection is obtained to calculate the contact point position (S4). An error in the position or orientation of the reference workpiece 13 is calculated from the multiple contact point positions (S5), and the position or orientation of the manipulator 10 is corrected to cancel out the calculated error (S7).

Description

Technical Field

[0001] The present disclosure relates to a method for adjusting the position of a manipulator that adjusts the loading position when loading and unloading a workpiece to and from a machine tool using an industrial robot by means of the manipulator.

Background Art

[0002] In an automatic production system composed of equipment such as an industrial robot equipped with a manipulator and a machine tool, a workpiece material is picked up from a workstock, which is a placement location for workpieces, and loaded into the machine tool. After the machine tool processes the workpiece, the industrial robot automatically performs a series of operations of unloading the processed workpiece and returning it to the workstock using the manipulator. The operation of the manipulator of this industrial robot is taught by the teaching operation of the position and posture of the end effector at each position on the operation locus. In the teaching operation, the manipulator is positioned at a desired position using an operation pendant, and the current position of each axis of the manipulator at that time is recorded.

[0003] In the teaching of the position for loading a workpiece into a machine tool and causing the grasping part of the machine tool to grasp the workpiece, when it is necessary to keep the grasping position within a predetermined tolerance, for example, at the grasping position and a nearby preparation position, the position and posture of the workpiece are finely adjusted. As one method of performing this fine adjustment, fine adjustment of the position and posture of the manipulator can be mentioned. However, this fine adjustment is often performed visually, which is a very time-consuming and laborious task. In addition, the relative position between the machine tool and the industrial robot changes slightly due to the change over time of the surrounding environment such as the floor foundation, and the loading position is displaced. Therefore, periodic re-teaching is required, which is time-consuming and laborious each time. Therefore, in order to perform teaching efficiently, means for measuring the position and posture between the workpiece and the machine tool is important.

[0004] Patent Document 1 discloses a method for measuring the position and orientation of a workpiece by using two sensor units installed around a chuck that grips a workpiece inside a machine tool. This measurement is performed by rotating the sensor units around the chuck and performing the same measurement, and the position and orientation of the workpiece can be adjusted based on the measurement results.

[0005] Patent Document 2 discloses a method in which, while the manipulator is inside the machine tool, a camera mounted on the robot photographs a marker installed inside the machine tool and stores it as a reference image. When the manipulator enters the machine tool again, the marker is photographed again, and the amount of attitude error of the manipulator is estimated from the difference between the photographed image and the reference image. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Special Publication No. 2022-522131 [Patent Document 2] Patent No. 6785931 [Overview of the project] [Problems that the invention aims to solve]

[0007] The method described in Patent Document 1 has the drawback of requiring a special sensor unit to be installed around the chuck. Furthermore, the sensor unit needs to be attached and detached before and after teaching, and since this basically requires human intervention, it cannot be automated. On the other hand, the method described in Patent Document 2 has the drawback of requiring a relatively expensive camera. Furthermore, marker photography using a camera cannot measure position with high precision, making it unsuitable when the positional tolerance required for workpiece gripping in a machine tool is small. In addition, there is the problem that the workpiece gripping position cannot be accurately measured because the marker photography position and the workpiece gripping position are different.

[0008] Therefore, the present disclosure aims to provide a manipulator position adjustment method that measures the position and orientation of a workpiece near the loading position when the workpiece gripped by the manipulator of an industrial robot is loaded into a machine tool, using a contact-type sensor attached to the tool spindle of the machine tool, and adjusts the position and orientation of the manipulator's end effector based on the measurement results. [Means for solving the problem]

[0009] To solve the above problems, the first configuration of this disclosure is a machine tool comprising a chuck capable of gripping a workpiece, a tool rest on which a tool can be mounted, and three or more translational drive shafts that enable translational motion of the tool rest, In a machining system comprising a manipulator having an end effector capable of gripping a workpiece and multiple joint drive axes, A method for adjusting the position of a manipulator, which adjusts the position or orientation of the end effector at the workpiece gripping position where the end effector grips the workpiece and allows the chuck to grip the workpiece, A first reference object positioning step involves positioning the manipulator so that a reference object having a specific shape, which is gripped or fixed to the end effector, is located at a workpiece gripping preparation position near the workpiece gripping position. A first reference object position measurement step involves mounting a contact sensor on a tool stand, moving the tool stand so that the contact sensor makes contact with the reference object positioned in the first reference object positioning step, obtaining the position of the translational drive axis at the moment the contact sensor detects contact, and calculating the contact point position from the obtained translational drive axis position. A first reference object position error calculation step calculates the error in the position or orientation of a reference object gripped or fixed to an end effector from multiple contact point positions obtained by performing a first reference object position measurement step on multiple locations of the reference object, and the command values ​​for the position and orientation of the end effector in the first reference object positioning step. The method is characterized by performing a first manipulator position correction step, which corrects the position or orientation of the end effector so as to cancel out the position or orientation error of the reference object calculated in the first reference object position error calculation step. Another aspect of the first configuration is a second reference object positioning step in which the manipulator positions the reference object, which is gripped or fixed to the end effector, to a position or orientation different from that of the first reference object positioning step, The second reference object position measurement step involves moving the tool rest so that a contact sensor mounted on the tool rest makes contact with the reference object gripped or fixed to the end effector positioned in the second reference object positioning step, acquiring the position of the translational drive axis at the moment the contact sensor detects contact, and calculating the contact point position from the acquired position of the translational drive axis. A first reference object dimension measurement step calculates the dimensions of a reference object from multiple contact point positions obtained by performing a second reference object position measurement step on multiple locations of the reference object, Further execution, The first step of calculating the position error of a reference object is characterized by further using the dimensions of the reference object calculated in the first step of measuring the dimensions of the reference object to calculate the error in the position or orientation of the reference object held or fixed to the end effector. Another aspect of the present disclosure is characterized in that, in the above configuration, if the error in the position or orientation of the reference object calculated in the first reference object position error calculation step is greater than or equal to a predetermined threshold, the steps from the first reference object positioning step to the first manipulator position correction step are repeated. To solve the above problems, the second configuration of the present disclosure is a machine tool comprising a chuck capable of gripping a workpiece, a tool rest on which a tool can be mounted, and three or more translational drive shafts that enable translational motion of the tool rest, In a machining system comprising a manipulator having an end effector capable of gripping a workpiece and multiple joint drive axes, A method for adjusting the position of a manipulator, which adjusts the position or orientation of the end effector at the workpiece gripping position where the end effector grips the workpiece and allows the chuck to grip the workpiece, A first confirmation and positioning step involves positioning the manipulator so that a reference object having a specific shape, which is gripped or fixed to the end effector, is located at a preset workpiece confirmation position. A first verification measurement step involves mounting a contact sensor on a tool stand, moving the tool stand so that the contact sensor makes contact with a reference object positioned in the first verification positioning step, obtaining the position of the translational drive shaft at the moment the contact sensor detects contact, and calculating the contact point position from the obtained translational drive shaft position. A first verification position calculation step calculates the position or orientation of a reference object gripped or fixed to an end effector from multiple contact point positions obtained by performing a first verification measurement step on multiple locations of the reference object, A first position change amount calculation step calculates the amount of change in the position or orientation of a reference object from the calculated value of the position or orientation of the reference object calculated in the first confirmation position calculation step and the stored value of the position or orientation of the reference object that has been measured and stored in advance. A first confirmation position correction step corrects the position or orientation of the end effector so as to cancel out the amount of change calculated in the first position change calculation step, It is characterized by performing the following. Another aspect of the second configuration is a configuration in which the manipulator is positioned such that a reference object gripped or fixed to the end effector is in a different position or orientation than that in the first confirmation positioning step, The second confirmation position measurement step involves moving the tool rest so that a contact sensor mounted on the tool rest makes contact with a reference object gripped or fixed to the end effector positioned in the second confirmation position step, acquiring the position of the translational drive axis at the moment the contact sensor detects contact, and calculating the contact point position from the acquired position of the translational drive axis. A second reference object dimension measurement step is performed, which involves calculating the dimensions of the reference object from multiple contact point positions obtained by performing a second confirmation position measurement step on multiple locations of the reference object. The first confirmation position calculation step is characterized by further using the dimensions of the reference object measured in the second reference object dimension measurement step to calculate the position or orientation of the reference object held or fixed to the end effector. Another aspect of the second configuration is characterized in that, in the above configuration, if the amount of change calculated in the first position change amount calculation step is greater than or equal to a predetermined threshold, the steps from the first confirmation position step to the first confirmation position correction step are repeated. To solve the above problems, the third configuration of this disclosure is a machine tool comprising a chuck capable of gripping a workpiece, a tool rest on which a tool can be mounted, and a translational drive shaft for translating the tool rest, wherein the degree of freedom of the translational motion of the tool rest is 2 or less. In a machining system comprising a manipulator having an end effector capable of gripping a workpiece and multiple joint drive axes, A method for adjusting the position of a manipulator, which adjusts the position or orientation of the end effector at the workpiece gripping position where the end effector grips the workpiece and allows the chuck to grip the workpiece, A third reference object positioning step involves positioning the manipulator so that a reference object having a specific shape, which is gripped or fixed to the end effector, is located at a workpiece gripping preparation position near the workpiece gripping position. A first machine tool position measurement step involves moving the tool rest so that a contact sensor mounted on the tool rest makes contact with a reference object positioned in the third reference object positioning step, acquiring the position of the translational drive axis at the moment the contact sensor detects contact, and calculating the machine tool contact point position from the acquired translational drive axis position. A first sensor positioning step involves positioning the tool rest so that a contact sensor mounted on the tool rest is in a position ready to grip the workpiece, A first manipulator position measurement step involves moving the end effector so that a reference object gripped or fixed to the end effector contacts a contact sensor positioned in the first sensor positioning step, acquiring the position of the joint drive axis at the time the contact sensor detects contact, and calculating the manipulator contact point position from the acquired joint drive axis position. A second reference object position error calculation step calculates the error in the position or orientation of the reference object gripped or fixed to the end effector at the workpiece gripping preparation position, based on the command values ​​of the position and orientation of the end effector in the third reference object positioning step, the multiple machine tool contact point positions obtained by performing the first machine tool position measurement step on multiple locations of the reference object, the command values ​​of the positions of multiple tool rests when the first sensor positioning step is performed at multiple positions of the workpiece gripping preparation position, and the multiple manipulator contact point positions obtained by performing the first manipulator position measurement step at multiple positions of the workpiece gripping preparation position. The method is characterized by performing a second manipulator position correction step, which corrects the position or orientation of the end effector so as to cancel out the position or orientation error of the reference object calculated in the second reference object position error calculation step. Another aspect of the third configuration is a fourth reference object positioning step in which the manipulator positions the reference object, which is gripped or fixed to the end effector, to a position or orientation different from that of the third reference object positioning step, In the fourth reference object positioning step, the tool rest is moved so that a contact sensor mounted on the tool rest makes contact with the reference object that was positioned in the fourth reference object positioning step, the position of the translational drive shaft is obtained at the moment the contact sensor detects contact, and the position of the machine tool contact point is calculated from the obtained position of the translational drive shaft. A third reference object dimension measurement step is performed, which calculates the dimensions of the reference object from the multiple machine tool contact point positions obtained by performing a second machine tool position measurement step on multiple locations of the reference object. In the second step of calculating the reference object position error, the error in the position or orientation of the reference object held or fixed to the end effector is calculated by further using the reference object dimensions obtained in the third step of measuring the reference object dimensions. Another aspect of the third configuration is characterized in that, in the above configuration, when the error in the position or orientation of the reference object calculated in the second reference object position error calculation step is greater than or equal to a predetermined threshold value, the steps from the third reference object positioning step to the second manipulator position correction step are repeated. In order to solve the above problems, a fourth configuration of the present disclosure includes a chuck capable of grasping a workpiece, a tool post capable of mounting a tool, a translational drive shaft for causing the tool post to perform a translational movement, and a machine tool in which the degree of freedom of the translational movement of the tool post is two or less degrees of freedom, a manipulator having an end effector capable of gripping a workpiece and a plurality of joint drive shafts, in a machining system. A method for adjusting the position or orientation of a manipulator at a workpiece grasping position for causing the workpiece grasped by an end effector to be grasped by a chuck, a third confirmation positioning step of positioning the manipulator so that a reference object having a specific shape held or fixed by the end effector is located at a workpiece confirmation position different from the workpiece grasping position, a third machine tool position measurement step of moving the tool post so that a contact type sensor mounted on the tool post contacts the reference object positioned in the third confirmation positioning step, acquiring the position of the translational drive shaft when the contact type sensor detects contact, and calculating the machine tool contact point position from the acquired position of the translational drive shaft, a second sensor positioning step of positioning the tool post so that the contact type sensor mounted on the tool post is located at the workpiece confirmation position, a second manipulator position measurement step of moving the end effector so that the reference object held or fixed by the end effector contacts the contact type sensor positioned in the second sensor positioning step, acquiring the position of the joint drive shaft when the contact type sensor detects contact, and calculating the manipulator contact point position from the acquired position of the joint drive shaft, The command values of the position and orientation of the end effector in the third confirmation positioning step, the plurality of machine tool contact point positions obtained by executing the third machine tool position measurement step for a plurality of locations of the reference object, the command values of the positions of the plurality of tool carriers when executing the second sensor positioning step at the plurality of positions of the workpiece confirmation position, and the plurality of manipulator contact point positions obtained by executing the second manipulator position measurement step at the plurality of positions of the workpiece confirmation position, a second confirmation position calculation step for calculating the position or orientation of the reference object held or fixed by the end effector at the workpiece confirmation position, A second position change amount calculation step for calculating the change amount of the position or orientation of the reference object from the calculated value of the position or orientation of the reference object calculated in the second confirmation position calculation step and the stored value of the position or orientation of the reference object measured and stored in advance, A second confirmation position correction step for correcting the position or orientation of the end effector so as to cancel the change amount calculated in the second position change amount calculation step, and characterized by executing the above. Another aspect of the fourth configuration is that, in the above configuration, when the change amount of the position or orientation of the reference object calculated in the second position change amount calculation step is greater than or equal to a predetermined threshold value, the steps from the third confirmation positioning step to the second confirmation position correction step are repeated. To solve the above problems, a fifth configuration of the present disclosure is a machine tool including a chuck capable of gripping a workpiece, a tool carrier capable of mounting a tool, and a translational drive shaft for translating the tool carrier, In a machining system including a manipulator having an end effector capable of gripping a workpiece and a plurality of joint drive shafts, A method for adjusting the position or orientation of a manipulator for adjusting the position or orientation of an end effector at a workpiece gripping position where the end effector grips a workpiece and the chuck grips the workpiece, A third sensor positioning step for positioning the tool carrier so that a contact sensor mounted on the tool carrier is located at a workpiece gripping preparation position near the workpiece gripping position, A third manipulator position measurement step involves moving the end effector so that a reference object gripped or fixed to the end effector contacts a contact sensor positioned in the third sensor positioning step, obtaining the position of the joint drive axis at the time the contact sensor detects contact, and calculating the contact point position from the obtained position of the joint drive axis. A third reference object position error calculation step calculates the error in the position or orientation of a reference object gripped or fixed to the end effector at a workpiece gripping preparation position from command values ​​of the positions of multiple tool rests when the third sensor positioning step is performed at multiple positions of the workpiece gripping preparation position and multiple contact point positions obtained by performing the third manipulator position measurement step at multiple positions of the workpiece gripping preparation position. The method is characterized by performing a third manipulator position correction step, which corrects the position or orientation of the end effector so as to cancel out the position or orientation error of the reference object calculated in the third reference object position error calculation step. Another aspect of the fifth configuration is a fourth sensor positioning step in which the tool rest is positioned such that a contact sensor mounted on the tool rest is located at a dimensional measurement position different from the workpiece gripping preparation position, A fourth manipulator position measurement step involves moving the end effector so that a reference object gripped or fixed to the end effector comes into contact with a contact sensor positioned in the fourth sensor positioning step, acquiring the position of the joint drive axis at the moment the contact sensor detects contact, and calculating the contact point position from the acquired position of the joint drive axis. A fifth reference object dimension measurement step is performed, which calculates the dimensions of the reference object from the multiple contact point positions obtained by performing the fourth manipulator position measurement step on multiple locations of the reference object. In the third step of calculating the reference object position error, the error in the position or orientation of the reference object held or fixed to the end effector is calculated by further using the reference object dimensions obtained in the fifth step of measuring the reference dimensions. Another aspect of the fifth configuration is characterized in that, in the above configuration, if the error in the position or orientation of the reference object calculated in the third reference object position error calculation step is greater than or equal to a predetermined threshold, the steps from the third sensor positioning step to the third manipulator position correction step are repeated. Another aspect of the fifth configuration is characterized in that, in the above configuration, the degree of freedom of the translational motion of the tool stand is 2 degrees of freedom or less. To solve the above problems, the sixth configuration of this disclosure is a machine tool comprising a chuck capable of gripping a workpiece, a tool rest on which a tool can be mounted, and a translation drive shaft for translating the tool rest, In a machining system comprising a manipulator having an end effector capable of gripping a workpiece and multiple joint drive axes, A method for adjusting the position of a manipulator, which adjusts the position or orientation of the end effector at the workpiece gripping position where the end effector grips the workpiece and allows the chuck to grip the workpiece, A fifth sensor positioning step involves positioning the tool rest so that a contact sensor mounted on the tool rest is located at a workpiece confirmation position different from the workpiece gripping position, A fifth manipulator position measurement step involves moving the end effector so that a reference object gripped or fixed to the end effector contacts a contact sensor positioned in the fifth sensor positioning step, obtaining the position of the joint drive axis at the time the contact sensor detects contact, and calculating the contact point position from the obtained position of the joint drive axis. A third confirmation position calculation step calculates the position or orientation of a reference object held by the end effector from command values ​​of the positions of multiple tool rests when the fifth sensor positioning step is performed at multiple positions of the workpiece confirmation position, and multiple contact point positions obtained by performing the fifth manipulator position measurement step at multiple positions of the workpiece confirmation position. A third position change calculation step calculates the amount of change in the position or orientation of a reference object from the calculated value of the position or orientation of the reference object calculated in the third confirmation position calculation step and the stored value of the position or orientation of the reference object that has been measured and stored in advance. The method is characterized by performing a third confirmation position correction step, which corrects the position or orientation of the end effector so as to cancel out the amount of change calculated in the third position change calculation step. Another aspect of the sixth configuration is characterized in that, in the above configuration, if the amount of change in the position or orientation of the reference object calculated in the third position change amount calculation step is greater than or equal to a predetermined threshold, the steps from the fifth sensor positioning step to the third confirmation position correction step are repeated. Another aspect of the sixth configuration is characterized in that, in the above configuration, the degree of freedom of the translational motion of the tool stand is 2 degrees of freedom or less. [Effects of the Invention]

[0010] According to this disclosure, a contact sensor is used to measure the position or orientation of a reference object brought in by the manipulator, and the position or orientation of the manipulator is adjusted based on the measurement results. Therefore, there is no need to use special equipment such as special sensor units or cameras. Accordingly, the position adjustment of the manipulator can be performed using a relatively inexpensive contact sensor, such as a touch probe, which is an accessory of a machine tool. Furthermore, by calculating the position and orientation of a reference object based on the position of a contact-type sensor positioned with the high positioning accuracy of the machine tool, the position and orientation of the workpiece can be adjusted with high precision. Furthermore, since measurements using contact sensors can be performed automatically, it becomes possible to automatically adjust the position of the workpiece. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram of the machine tool related to this disclosure. [Figure 2] This is a schematic diagram of the processing cell related to this disclosure. [Figure 3] This is a schematic diagram showing the positional relationship of the reference workpiece at the workpiece gripping preparation position. [Figure 4] This is a flowchart of the first method of disclosure. [Figure 5] This is a schematic diagram of the positional and orientation errors of the reference workpiece at the workpiece gripping preparation position. [Figure 6] This is a schematic diagram of the measurement of a cylindrical reference workpiece at the workpiece gripping preparation position. [Figure 7] This is a schematic diagram of the measurement of a prism-shaped reference workpiece at the workpiece gripping preparation position. [Figure 8] This is a flowchart showing the second method of disclosure. [Figure 9] This is a schematic diagram showing the positional relationship of the reference workpiece at the dimension measurement location. [Figure 10] This is a schematic diagram of the measurement of a cylindrical reference workpiece at the measurement position. [Figure 11] This is a schematic diagram of the measurement position of a rectangular prism-shaped reference workpiece at the dimension measurement location. [Figure 12] This is a flowchart of the third method of disclosure. [Figure 13] This is a schematic diagram showing the positional relationship of the reference workpiece at the verification measurement location. [Figure 14] This is a flowchart of the fourth method of disclosure. [Figure 15] This is a schematic diagram of a two-axis horizontal lathe related to this disclosure. [Figure 16] This is a schematic diagram of the processing cell related to this disclosure. [Figure 17] This is a flowchart of the fifth method of disclosure. [Figure 18] This is a schematic diagram showing the positional relationship of the workpiece gripping preparation positions. [Figure 19] This is a schematic diagram of the measurement of a cylindrical reference workpiece at the workpiece gripping preparation position. [Figure 20] This is a schematic diagram of the measurement of a cylindrical reference workpiece at the workpiece gripping preparation position. [Figure 21] This is a schematic diagram of the measurement of a cylindrical reference workpiece at the workpiece gripping preparation position. [Figure 22] This is a schematic diagram of the measurement position of a prism-shaped reference workpiece at the workpiece gripping preparation position. [Figure 23] This is a flowchart of the sixth method of disclosure. [Figure 24] This is a schematic diagram showing the positional relationship of the dimensional measurement locations. [Figure 25] This is a schematic diagram of the measurement of a reference workpiece at the dimensional measurement position. [Figure 26] This is a flowchart of the seventh method of disclosure. [Figure 27] This is a schematic diagram showing the positional relationship of the workpiece inspection locations. [Figure 28] This is a flowchart of the eighth method of disclosure. [Figure 29] This is a schematic diagram of the measurement position of a cylindrical reference workpiece at the workpiece gripping preparation position. [Figure 30] This is a schematic diagram of the measurement position of a cylindrical reference workpiece at the workpiece gripping preparation position. [Figure 31] This is a schematic diagram of the measurement of a reference workpiece at the dimensional measurement position. [Figure 32] This is a flowchart of the ninth disclosure method. [Figure 33] This is a flowchart of the tenth method of disclosure. [Modes for carrying out the invention]

[0012] Hereinafter, embodiments of this disclosure will be described in detail with reference to the drawings. Figure 1 is an explanatory diagram of the manipulator position adjustment method according to this disclosure, and shows an example of a machine tool. In machine tool 1, the tool rest 2A incorporates a rotatable tool spindle and can be fitted with tools 7 such as an end mill (a rotary tool) and a cutting tool (a non-rotatable tool). The tool rest 2A is capable of rotational motion with one degree of freedom on the B axis. In addition, the tool rest 2A is capable of translational motion with three degrees of freedom on the mutually orthogonal X, Y, and Z axes. Chuck 4 has multiple jaws that can be opened and closed, and is capable of gripping a workpiece. Chuck 4 is also rotatable by the turning spindle 3. Chuck 6, positioned opposite chuck 4, has multiple jaws that can be opened and closed, and is rotatable by the second turning spindle 5. Chuck 6 is also capable of one degree of freedom of translational motion via the W-axis (shown in Figure 3). The drive mechanisms such as feed axes and motors related to the operation of each part of the machine tool 1 are controlled by a numerical control device NC1 (not shown in the figure). The numerical control device NC1 includes a CPU and memory connected to the CPU, and various processes are realized by utilizing them.

[0013] Figure 2 is a schematic diagram showing an example of a machining cell. The machining cell 30 as a machining system in this disclosure includes a machine tool 1, a manipulator 10, and a workpiece stocker 20, as shown in Figure 2. The workpiece stocker 20 can store multiple workpieces 12. The manipulator 10 is equipped with six joints and actuators. Therefore, the manipulator 10 is capable of six degrees of freedom of movement of the position and orientation of the end effector 11 attached to its end face. The end effector 11 is equipped with an openable and closable hand and is capable of gripping the workpiece 12. The drive mechanism for the operation of each part of the manipulator 10 is controlled by a numerical control device NC2, which is not shown in the figure. The numerical control device NC2 includes a CPU and memory connected to the CPU, and various processes are realized by utilizing them.

[0014] The manipulator 10 grasps the workpiece 12 stored in the workstocker 20 with the hand of the end effector 11 and removes it. Subsequently, the manipulator 10 carries the workpiece 12 into the machine tool 1 and positions the workpiece 12 in a workpiece gripping position where the chuck 4 grips the workpiece 12. Then, as the chuck 4 grips the workpiece 12, the manipulator 10 opens the hand of the end effector 11 and retracts from the machine tool 1. Subsequently, machine tool 1 processes the workpiece 12. Once machine tool 1 has finished processing the workpiece 12, manipulator 10 removes the workpiece 12 held in chuck 4 and returns it to workpiece stocker 20. By performing this series of operations for multiple workpieces 12, machining of all workpieces 12 can be performed automatically.

[0015] The machining operations of machine tool 1 are performed according to a pre-created program. On the other hand, the operation of manipulator 10 is performed according to teaching data, which is pre-programmed to store the angles of each joint of manipulator 10 positioned in a desired position and orientation. Examples of teaching positions include the gripping and approach positions of each workpiece 12 in the workstocker 20, intermediate passing points, the workpiece loading position within machine tool 1, and the workpiece gripping and approach positions for the chuck 4 to grip the workpiece 12. The absolute positioning accuracy of the manipulator 10 is not high, and is generally 0.1 mm or more. Therefore, if the fit tolerance of the chuck 4 is on the order of 0.01 mm, the workpiece gripping position and the approach position to the workpiece gripping position must be adjusted with high precision.

[0016] Figure 3 is a schematic diagram of the positional relationship of the reference workpiece at the workpiece gripping preparation position 14, which will be described later. In this embodiment, a touch probe 8, as shown in Figure 3, is used to adjust the position of the manipulator 10. The touch probe 8 is a contact-type sensor. The touch probe 8 has a stylus with a spherical tip, and outputs a signal when it detects that the stylus has come into contact with the object to be measured. Generally, when using a touch probe 8 with a machine tool 1, the touch probe 8 is mounted on a tool rest 2A. In this case, the tool rest 2A is moved so that the touch probe 8 contacts the object to be measured, and the numerical control device NC1 of the machine tool 1 receives the output signal when the touch probe 8 and the object to be measured come into contact. Subsequently, the numerical control device NC1 acquires the position of each translational drive axis at the time the signal is received or at a time that takes delay into account. Based on the acquired positions of each translational drive axis, the numerical control device NC1 performs calculations considering a preset correction value to measure the axial contact point position of the translational drive axis. In this way, since the position of the contact point is measured by the movement of the tool rest 2A, the motion accuracy of the machine tool 1 becomes the measurement accuracy. If there are three or more translational drive axes, the three-dimensional position can be measured by contact from three directions.

[0017] On the other hand, the manipulator 10 may also be used with a touch probe 8 attached. In this case, the touch probe 8 is attached to the end effector 11. The end effector 11 is then moved so that the touch probe 8 makes contact with the object to be measured, and the numerical control device NC2 of the manipulator 10 receives the output signal when the touch probe 8 and the object to be measured make contact. Subsequently, the numerical control device NC2 acquires the position of each joint drive axis at the time the signal is received or at a time that takes delay into account. Based on the acquired joint drive axis positions, the numerical control device NC2 performs calculations that take into account forward kinematics calculations, deformation errors due to gravity, and preset correction values ​​to determine the position and orientation of the manipulator 10 at the point of contact. However, as mentioned above, the motion accuracy of the manipulator 10 is lower than that of the machine tool 1. Therefore, when using the touch probe 8 with the manipulator 10, the measurement accuracy will be lower compared to when using the touch probe 8 with the machine tool 1. Therefore, in this disclosure, as described later, the touch probes 8 attached to the tool bases 2A and 2B of the machine tool 1 are shared and used by the machine tool 1 and the manipulator 10. That is, by making it possible for both the numerical control device NC1 of the machine tool 1 and the numerical control device NC2 of the manipulator 10 to receive the output signal emitted by one touch probe 8, it is possible to arbitrarily select which of the numerical control devices NC1 or NC2 calculates the contact position.

[0018] The method for adjusting the position of the manipulator 10 with respect to the machine tool 1 configured as described above will be explained below. The method for adjusting the position of the first manipulator will be explained using the flowchart in Figure 4. In step S1, the touch probe 8 is attached to the tool base 2A. In step S2, the end effector 11 of the manipulator 10 grips the reference workpiece 13. Here, the reference workpiece 13 may be fixed to the end effector 11. Alternatively, an end effector 11 having a portion equivalent to the reference workpiece 13 may be used.

[0019] The reference workpiece 13 is a measurement reference object having a specific shape. The reference workpiece 13 may have a rectangular prism shape or a cylindrical shape, for example, as will be described later.

[0020] In step S3, the manipulator 10 is positioned so that the reference workpiece 13, gripped by the end effector 11, is positioned at the workpiece gripping preparation position 14 inside the machine tool 1 as shown in Figure 3 (first reference workpiece positioning step). The workpiece gripping preparation position 14 is the position where the workpiece 12, gripped by the end effector 11 of the manipulator 10, is prepared to be gripped by the chuck 4. The preparation position is also called the approach position. The workpiece gripping preparation position 14 is, for example, a position on the rotation axis S of the turning spindle 3 that is close to the workpiece gripping position.

[0021] As shown in Figure 3, when the reference workpiece 13 is cylindrical, the central axis W of the reference workpiece 13 at the workpiece gripping preparation position 14 is parallel to the rotation axis S of the turning spindle 3. Also, the X,Y coordinates of the center of the reference workpiece 13 coincide with the X,Y coordinates of the rotation center of the turning spindle 3, i.e., the gripping center of the chuck 4. However, if the positional relationship between the manipulator 10 and the machine tool 1 is not sufficiently adjusted, or if the positional relationship changes over time, the central axis W of the reference workpiece 13 will be tilted or offset with respect to the rotation axis S of the turning spindle 3, as shown in Figure 5. Figure 5 shows a schematic diagram of the positional and orientation errors of the reference workpiece 13 at the workpiece gripping preparation position 14.

[0022] In step S4, the positions of multiple points on the reference workpiece 13, which is positioned at the workpiece gripping preparation position 14, are measured. Specifically, the touch probe 8 is brought into contact with multiple points on the reference workpiece 13, and the contact point positions are measured from the translational drive position of the tool rest 2A (first reference workpiece position measurement step). The case where the reference workpiece 13 is cylindrical will be explained. Figure 6 shows a schematic diagram of the measurement position of the cylindrical reference workpiece at the workpiece gripping preparation position 14. When the reference workpiece 13 is cylindrical, as shown in Figure 6, the touch probe 8 is brought into contact with a total of 6 contact points P1 to P6, and the contact point position in each contact direction is measured. However, for the two directions other than the contact direction, the same values ​​as the command position are obtained. Here, if the diameter of the reference workpiece 13 is known precisely, the contact point P6 does not need to be measured.

[0023] The case where the reference workpiece 13 is a square prism shape will be explained. Figure 7 shows a schematic diagram of the measurement position of the prism-shaped reference workpiece at the workpiece gripping preparation position 14. When the reference workpiece 13 is a square prism shape, as shown in Figure 7, the touch probe 8 is brought into contact with a total of 7 contact points P1 to P7, and the position of each contact point is measured. In this case, if the width D' of the reference workpiece 13 is precisely known, the contact point P6 does not need to be measured.

[0024] In step S5, the position and orientation errors of the reference workpiece 13 are calculated from the contact point positions measured in step S4 (first reference object position error calculation step). Let's explain the case where the reference workpiece 13 is cylindrical. If the position measurements of the contact point Pi (i=1~6) are (pxi, pyi, pzi), the tilt error dAw of the reference workpiece 13 around the X axis can be calculated using the following equation (1). The tilt error dBw around the Y axis can be calculated using equation (2). dAw = (py3 - py2) / (pz3 - pz2) (1) dBw = (px5 - px4) / (pz5 - pz4) (2)

[0025] Furthermore, the X-direction error dXw of the center of the bottom surface of the reference workpiece 13 can be calculated using the following equation (3). Also, the Y-direction error dYw of the center of the bottom surface of the reference workpiece 13 can be calculated using the following equation (4). Here, the center positions X and Y of the turning spindle 3 are assumed to be x0 and y0, respectively. dXw = px4 - (py2 - py6) / 2 - x0 (3) dYw = (py2 + py6) / 2 - y0 (4)

[0026] As mentioned above, if the diameter D of the reference workpiece 13 is known precisely, measurement of the contact point P6 is unnecessary. In this case, the X-direction error dXw of the center of the bottom surface of the reference workpiece 13 can be calculated using the following equation (5). Also, the Y-direction error dYw of the center of the bottom surface of the reference workpiece 13 can be calculated using the following equation (6). dXw = px4 - D / 2 - x0 (5) dYw = py2 + D / 2 - y0 (6)

[0027] The Z-direction error dZw of the end face of the reference workpiece 13 is calculated using the following equation (7). Here, z0 is defined as the distance from the Z-direction position of the end face of the chuck 4 to the assumed Z-direction position of the workpiece gripping preparation position 14. dZw = pz1 - z0 (7)

[0028] Next, we will explain the case where the reference workpiece 13 is a regular rectangular prism. Basically, dXw, dYw, dZw, dAw, and dBw can be calculated in the same way as in the case of a cylindrical shape. On the other hand, the tilt error dCw around the Z axis can be calculated using the following equation (8). dCw = (py2 - py7) ​​ / (px2 - px7) (8)

[0029] The shape of the reference workpiece 13 is not limited to a cylindrical or square prism shape; it may also be a polyhedron or a shape with multiple spheres. In the measurement of a spherical shape, the center position of the sphere can be measured by contact at four or more points, and the error in the position and orientation of the reference workpiece 13 can be determined from the center positions of three or more spheres.

[0030] In step S6, it is determined whether the position and orientation errors of the reference workpiece 13, which were determined in step S5, are below a predetermined threshold. If the position and orientation errors of the reference workpiece 13 are below the threshold, the error is considered small, and the position adjustment of the manipulator 10 is completed. On the other hand, if the error in the position and orientation of the reference workpiece 13 is greater than the threshold, correction is performed in step S7 (first manipulator position correction step). In this case, steps S3 to S7 are repeatedly executed until the error in the position and orientation of the reference workpiece 13 falls below the threshold. Note that the position adjustment of the manipulator 10 may be terminated after a certain number of repetitions.

[0031] In step S7, the position and orientation commands for the end effector 11 are corrected to cancel out the position and orientation errors of the reference workpiece 13 obtained in step S5. One method of correction is to set a local coordinate system when teaching the workpiece gripping preparation position 14 of the manipulator 10 and then correct that local coordinate system. Another method is to correct the teaching data when teaching the workpiece gripping preparation position 14.

[0032] Thus, in the first manipulator position adjustment method, the position or orientation of the reference workpiece 13 brought in by the manipulator 10 is measured using the touch probe 8, and the position or orientation of the manipulator 10 is adjusted based on the measurement result. Therefore, no special equipment such as special sensor units or cameras is used. For this reason, the position adjustment of the manipulator 10 can be performed using the relatively inexpensive touch probe 8, which is an accessory of the machine tool 1. Furthermore, in the first manipulator position adjustment method, the position and orientation of the workpiece can be adjusted with high precision by calculating the position and orientation of the reference workpiece 13 based on the position of the touch probe 8, which is positioned with high positioning accuracy in the machine tool 1. Furthermore, in the first manipulator position adjustment method, measurements using the touch probe 8 can be performed automatically, making it possible to automatically adjust the position of the workpiece.

[0033] Next, the second manipulator position adjustment method will be explained using the flowchart in Figure 8. This method is used when the dimensions of the reference workpiece 13 are not precisely known, and when the contact point P6 cannot be measured due to interference between the touch probe 8 or tool base 2A and the structure or end effector 11, or limitations in the operating range of the feed axis. Steps that overlap with the first manipulator position adjustment method shown in Figure 4 will not be explained in detail.

[0034] Figure 9 shows a schematic diagram in which the reference workpiece 13 is placed at the dimensional measurement position. After steps S1 and S2 are performed, in step S11, the manipulator 10 is positioned so that the reference workpiece 13, which is gripped by the end effector 11, is placed at a preset position (referred to as the "dimension measurement position 16") that is different from the workpiece gripping preparation position 14, as shown in Figure 9 (second reference workpiece positioning step).

[0035] In step S12, the touch probe 8 is used to measure the positions of multiple points on the reference workpiece 13 positioned at the dimensional measurement position 16 (second reference object position measurement step). The case where the reference workpiece 13 is cylindrical will be explained. Figure 10 shows a schematic diagram of the measurement position of the cylindrical reference workpiece at the dimension measurement position 16. When the reference workpiece 13 is cylindrical, as shown in Figure 10, the touch probe 8 is brought into contact with contact points P11 and P12, and the position of each contact point is measured.

[0036] The case where the reference workpiece 13 is a square prism shape will be explained. Figure 11 is a schematic diagram of the measurement position of the square prism-shaped reference workpiece at the dimension measurement position 16. When the reference workpiece 13 is a square prism shape, as shown in Figure 11, the touch probe 8 is brought into contact with contact points P11 and P12, and the position of each contact point is measured.

[0037] In step S13, the dimensions of the reference workpiece 13 are calculated from the contact point position measured in step S12 (first reference object dimension measurement step). If the reference workpiece 13 is cylindrical, and the positional measurements of the contact point Pi (i=11,12) are (pxi,pyi,pzi), then the diameter D of the reference workpiece 13 can be calculated using the following equation (9). D = pz12 - pz11 (9)

[0038] Similarly, if the reference workpiece 13 is a rectangular prism shape, the width D' of the reference workpiece 13 can be calculated using the above formula (9). Steps S3 to S7 are then performed in the same manner as in the first manipulator position adjustment method. In the second manipulator position adjustment method, if the error in the position and orientation of the reference workpiece 13 is greater than the threshold in step S6, steps S3 to S7 are repeatedly performed in the same manner as in the first manipulator position adjustment method until the error in the position and orientation of the reference workpiece 13 falls below the threshold. Steps S11 to S13 may be optionally included in this process.

[0039] Next, the third manipulator position adjustment method will be explained using the flowchart in Figure 12. The third manipulator position adjustment method is used when the reference workpiece 13 cannot be positioned at the workpiece gripping preparation position 14 due to interference between at least one of the touch probe 8 and the tool base 2A, for example, with another structure such as the end effector 11, and therefore position measurement at the workpiece gripping preparation position 14 is not possible. Furthermore, the third manipulator position adjustment method assumes that the workpiece gripping preparation position 14 has been adjusted at least once.

[0040] In step S21, the touch probe 8 is attached to the tool base 2A. In step S22, the reference workpiece 13 is gripped by the end effector 11 of the manipulator 10. The reference workpiece 13 may be fixed to the end effector 11. Alternatively, an end effector 11 having a portion equivalent to the reference workpiece 13 may be used.

[0041] Figure 13 shows a schematic diagram of the positional relationship of the reference workpiece at the confirmation measurement position. In step S23, the manipulator 10 is positioned so that the reference workpiece 13 is positioned at a predetermined position (referred to as "workpiece confirmation position 15") which is different from the workpiece gripping preparation position 14 shown in Figure 13 (first confirmation positioning step). In step S24, the touch probe 8 is used to measure the positions of multiple locations on the reference workpiece 13 positioned at the workpiece confirmation position 15 (first confirmation measurement step). The locations to be measured are the same as in step S4. In step S25, the position and orientation of the reference workpiece 13 are calculated from the contact point position measured in step S24 (first confirmation position calculation step). The calculation method is the same as in step S5, but x0, y0, and z0 in equations (3) to (7) above are set to 0. Alternatively, an error value may be calculated as in step S5.

[0042] In step S26, it is determined whether the position and orientation of the reference workpiece 13, which were determined in step S25, have been stored. If steps S23 to S25 are performed for the first time immediately after adjusting the workpiece gripping preparation position 14, the position and orientation of the reference workpiece 13 have not been stored. In that case, in step S30, the position and orientation of the reference workpiece 13, which were determined in step S25, are stored, and the position adjustment of the manipulator 10 is completed.

[0043] On the other hand, if it is determined that the position and orientation of the reference workpiece 13 are stored, in step S27, the difference between the calculated position and orientation of the reference workpiece 13 in S25 and the stored value is calculated as the amount of change in the position and orientation of the reference workpiece 13 (first position change amount calculation step). In step S28, it is determined whether the amount of change calculated in step S27 is below a predetermined threshold. If the amount of change calculated in step S27 is less than or equal to the threshold, the position adjustment of the manipulator 10 is terminated, as the amount of change is considered small. At this point, the stored values ​​may be updated using the calculated position and orientation values ​​of the reference workpiece 13. On the other hand, if the amount of change calculated in step S27 is greater than the threshold, position correction is performed in step S29 (first confirmation position correction step). In this case, steps S23 to S28 are repeatedly executed until the amount of change calculated in step S27 is less than or equal to the threshold. Alternatively, the position adjustment of the manipulator 10 may be terminated after a certain number of repetitions.

[0044] In step S29, the position and orientation commands of the end effector 11 are corrected to cancel out the changes in position and orientation of the reference workpiece 13 determined in step S27. One method of correction is to set a local coordinate system when teaching the workpiece gripping preparation position 14 of the manipulator 10 and then correct that local coordinate system. Another method is to correct the teaching data when teaching the workpiece gripping preparation position 14.

[0045] Next, the fourth manipulator position adjustment method will be explained using the flowchart in Figure 14. The fourth manipulator position adjustment method is used when the dimensions of the reference workpiece 13 are not precisely known, and the contact point P6 cannot be measured due to interference between at least one of the touch probe 8 and the tool base 2A, for example, with another structure such as the end effector 11. Steps that overlap with the third manipulator position adjustment method shown in Figure 12 will not be explained in detail.

[0046] After steps S21 and S22 are performed, in step S31, the manipulator 10 is positioned so that the reference workpiece 13 held by the end effector 11 is in a different position and orientation from the workpiece confirmation position 15, for example, a position and orientation such as the dimension measurement position 16 shown in Figure 9 (second confirmation positioning step). In step S32, similar to step S12, the positions of multiple points on the reference workpiece 13 positioned at the dimensional measurement position 16 are measured using the touch probe 8 (second confirmation position measurement step). In step S33, similar to step S13, the dimensions of the reference workpiece 13 are calculated from the contact point position measured in step S32 (second reference object dimension measurement step). Using the dimensions of the reference workpiece 13 measured in this way, the position and orientation of the reference workpiece 13 held by the end effector 11 are calculated through a first confirmation positioning step (S23), a first confirmation measurement step (S24), and a first confirmation position calculation step (S25). Subsequently, steps S23 to S29 are executed as appropriate to adjust the position of the manipulator 10.

[0047] The first to fourth manipulator position adjustment methods described above were explained using machine tool 1, which is capable of 3 degrees of freedom in translational motion, as an example. However, the following explanation will use machine tools with 2 or fewer degrees of freedom in translational motion as examples. Figure 15 shows a schematic diagram of a two-axis horizontal lathe 1a, which is a machine tool with two or fewer degrees of freedom in translational motion. As shown in Figure 15, the tool post 2B can be fitted with tools 7 such as end mills (rotary tools) and cutting tools (non-rotary tools). It is also capable of two degrees of freedom in translational motion along the mutually orthogonal X and Z axes. The chuck 4 has multiple jaws that can be opened and closed, is capable of gripping a workpiece, and is rotatable by the turning spindle 3. The drive mechanisms such as feed axes and motors related to the operation of each part of the two-axis horizontal lathe 1a are controlled by a numerical control device NC1, which is not shown in the figure. Note that the machine tool with two or fewer degrees of freedom in translational motion of the tool post according to this disclosure is not limited to the two-axis horizontal lathe 1a, but may also be, for example, a machining center with two or fewer degrees of freedom in translational motion of the tool post.

[0048] Figure 16 is a schematic diagram of a machining cell, showing an example of a machining cell related to a two-spindle horizontal lathe 1a. As shown in Figure 16, the machining cell 30a includes the two-spindle horizontal lathe 1a, a manipulator 10, and a workpiece stocker 20. The manipulator 10 and the workpiece stocker 20 are the same as those shown in Figure 1, as described above. Using the flowchart in Figure 17 and the schematic diagram of the positional relationship of the workpiece gripping preparation position 14 in Figure 18, the method for adjusting the position of the manipulator 10 in a two-axis horizontal lathe 1a as the fifth method for adjusting the position of the manipulator will be explained below.

[0049] In step S51, the touch probe 8 is attached to the tool rest 2B as shown in Figure 18. Since the two-axis horizontal lathe 1a has two translational drive axes, the X axis and the Z axis, it is possible to measure the two-dimensional position in the XZ plane. In step S52, the manipulator 10 is made to grip the reference workpiece 13 with its end effector 11. Here, the reference workpiece 13 may be fixed to the end effector 11. Alternatively, an end effector 11 having a portion equivalent to the reference workpiece 13 may be used.

[0050] In step S53, as shown in Figure 18, the manipulator 10 is positioned so that the reference workpiece 13 held by the end effector 11 is located in the workpiece gripping preparation position 14 inside the two-axis horizontal lathe 1a (third reference workpiece positioning step).

[0051] In step S54, the tool rest 2B is moved so that the touch probe 8 mounted on the tool rest 2B makes contact with the reference workpiece 13, and the numerical control device NC1 of the two-axis horizontal lathe 1a receives the output signal when the touch probe 8 makes contact with the object to be measured. Subsequently, the numerical control device NC1 acquires the position of each translational drive axis at the time the signal is received or at a time that takes delay into account. Based on the acquired positions of each translational drive axis, the numerical control device NC1 performs calculations that take into account a preset correction value and measures the axial contact point position of the translational drive axis (first machine tool position measurement step). Step S54, the first machine tool position measurement step, is repeatedly performed until it is confirmed that the measurement has been completed at a predetermined location.

[0052] The case where the reference workpiece 13 is cylindrical will be explained. Figure 19 is a schematic diagram of the measurement of a cylindrical reference workpiece at the workpiece gripping preparation position 14, and is an explanatory diagram of the movement of the touch probe 8. If the reference workpiece 13 is cylindrical, as shown in Figure 19, the touch probe 8 is moved in the Z-plus direction to make contact with a point on the cylindrical bottom surface of the reference workpiece 13, and the contact point P1(Xp1,zp1) is acquired. Furthermore, the touch probe 8 is moved in the X-minus direction to make contact with a point on the side surface of the reference workpiece 13, and contact points P2(xp2, Zp2) and P3(xp3, Zp3) are acquired. Here, Xp1, Zp2, and Zp3 are command values.

[0053] Figure 20 is a schematic diagram of the measurement of a cylindrical reference workpiece at the workpiece gripping preparation position 14, and is an explanatory diagram that includes the tool rest 2B. In step S55, the tool rest 2B is positioned so that the touch probe 8 is located near the workpiece gripping preparation position 14, as shown in Figure 20 (first sensor positioning step).

[0054] In step S56, the manipulator 10 is moved so that the reference workpiece 13, held by the end effector 11, makes contact with the touch probe 8 positioned near the workpiece gripping preparation position 14. The signal output by the touch probe 8 upon detecting contact is received not by the machine tool 1, but by the numerical control device NC2 of the manipulator 10. Subsequently, the numerical control device NC2 acquires the position of each joint drive axis at the time the signal is received or at a time considering the delay. Based on the acquired joint drive axis positions, the numerical control device NC2 performs calculations that take into account forward kinematics calculations, deformation errors due to gravity, and preset correction values ​​to determine the position and orientation of the manipulator 10 at the contact point. (First manipulator position measurement step). Step S56, the first manipulator position measurement step, is repeatedly performed until the completion of measurement at a predetermined location is confirmed.

[0055] Figure 21 is a schematic diagram illustrating the measurement of a cylindrical reference workpiece 13 at the workpiece gripping preparation position 14, and is an explanatory diagram for moving the reference workpiece 13. When the reference workpiece 13 is cylindrical, the measurement of the reference workpiece 13 begins with the touch probe 8 being positioned at Q4 (Xq4, Yq4, Zq4) on the cylindrical central axis w of the workpiece gripping preparation position 14, as shown in Figure 21. Then, as shown in Figure 21, the reference workpiece 13 is moved in the Y-minus and Y-plus directions respectively, and the touch probe 8 is brought into contact with the side surface of the reference workpiece 13, thereby obtaining the position and orientation Q4r (xr4, yr4, zr4, ar4, br4, cr4) of the contact point in the Y-plus direction relative to Q4, and the position and orientation Q6r (xr6, yr6, zr6, ar6, br6, cr6) of the contact point in the Y-minus direction.

[0056] Next, the touch probe 8 is positioned at Q5 (Xq5, Yq5, Zq5) on the central axis w of the cylinder at the workpiece gripping preparation position 14. Then, as shown in Figure 21, the reference workpiece 13 is moved in the Y-minus direction and the touch probe 8 is brought into contact with the side surface of the reference workpiece 13, and the position and orientation Q5r (xr5, yr5, zr5, ar5, br5, cr5) of the contact point relative to Q5 is obtained. Note that if the diameter D of the reference workpiece 13 is known precisely, measurement at Q6r may not be performed.

[0057] Next, we will explain the case where the reference workpiece 13 is a square prism shape. Figure 22 shows a schematic diagram of the measurement position of the prism-shaped reference workpiece at the workpiece gripping preparation position 14. If the reference workpiece 13 is a regular rectangular prism shape, as shown in Figure 22, a total of three locations Q4 on the Z-minus plane of the reference workpiece 13, and Q2 and Q3 on the X-plus plane are measured in steps S53 and S54. Then, a total of four locations Q4, Q5, and Q7 on the Y-minus plane of the reference workpiece 13, and Q6 on the Y-plus plane are measured in steps S55 and S56. Here, Q4 is a position offset in the X-positive direction from the central axis W' of the square prism-shaped reference workpiece 13. Q7 is a position offset in the X-negative direction from the central axis W' of the square prism-shaped reference workpiece 13. Measurement at Q7 obtains the position and orientation Q7r (xr7,yr7,zr7,ar7,br7,cr7) of the contact point. If the width D' in the Y direction of the reference workpiece 13 is known precisely, measurement at Q6r does not need to be performed.

[0058] Next, in step S57, the positional and orientation errors of the reference workpiece 13 are calculated (second reference object position error calculation step). First, let's explain the case where the reference workpiece 13 is cylindrical. The tilt error dAw of the reference workpiece 13 around the X axis can be calculated using the following equation (10). Also, the tilt error dBw of the reference workpiece 13 around the Y axis can be calculated using the following equation (11). dAw = (yr4 - yr5) / (Zq5 - Zq4) (10) dBw = (xp3 - xp2) / (Zp3 - Zp2) (11)

[0059] The X-direction error dXw of the center of the bottom surface of the reference workpiece 13 is calculated using the following equation (12). Similarly, the Y-direction error dYw of the center of the bottom surface of the reference workpiece 13 is calculated using the following equation (13). Here, ycn is the correction value in the negative Y direction, and ycp is the correction value in the positive Y direction, and are used to correct errors such as the radius and misalignment of the stylus sphere of the touch probe 8. Also, d is the assumed diameter value of the reference workpiece 13 for calculating the contact point on the manipulator 10. Furthermore, the center positions X and Y of the turning spindle 3 are assumed to be x0 and y0, respectively. dXw = xp2 - (yr4 + ycp - yr6 - ycn + d) / 2 - x0 (12) dYw = - (yr6 + ycn + yr4 + ycp) / 2 - y0 (13)

[0060] As described above, if the diameter D of the reference workpiece 13 is known precisely, measurement of the contact point P6 is unnecessary, and the X-direction error dXw of the center of the bottom surface of the reference workpiece 13 can be calculated using the following equation (14). Also, the X-direction error dYw of the center of the bottom surface of the reference workpiece 13 can be calculated using the following equation (15). dXw = px4 - D / 2 - x0 (14) dYw = - (yr4 - Yq4 + ycp) + D / 2 - y0 (15)

[0061] The Z-direction error dZw of the end face of the reference workpiece 13 is calculated using the following equation (16). Here, z0 is defined as the distance from the Z-direction position of the end face of the chuck 4 to the assumed Z-direction position of the workpiece gripping preparation position 14. dZw = pz1 - z0 (16)

[0062] Next, we will explain the case where the reference workpiece 13 is a square prism. When the reference workpiece 13 is a square prism, the calculations are basically performed in the same way as in the case of a cylindrical shape, and the X-direction error dXw of the center of the base of the reference workpiece 13, the Y-direction error dYw of the center of the base, the Z-direction error dZw of the end face, the tilt error around the X axis dAw, and the tilt error around the Y axis dBw are obtained using the above equations (10) to (16). However, the diameter D and assumed diameter value d in the above equations (10) to (16) are replaced with the width D' and assumed width dimension d', respectively. Furthermore, the tilt error dCw around the Z axis can be calculated using the following equation (17). dCw = (yr7 - yr2) / (Xq2 - Xq7) (17)

[0063] In step S58, it is determined whether the errors in the position and orientation of the reference workpiece 13, which were determined in step S57, are below a predetermined threshold. If the errors in the position and orientation of the reference workpiece 13 are below the threshold, the errors are considered small, and the position adjustment of the manipulator 10 is completed. On the other hand, if the error in the position and orientation of the reference workpiece 13 is greater than the threshold, correction is performed in step S59. In this case, steps S53 to S59 are repeatedly executed until the error in the position and orientation of the reference workpiece 13 falls below the threshold. Note that the position adjustment of the manipulator 10 may be terminated after a certain number of repetitions.

[0064] In step S59, the position and orientation commands of the end effector 11 are corrected to cancel out the changes in position and orientation of the reference workpiece 13 obtained in step S57 (second manipulator position correction step). One correction method is to set a local coordinate system when teaching the workpiece gripping preparation position 14 of the manipulator 10 and correct that local coordinate system. Another method is to correct the teaching data when teaching the workpiece gripping preparation position 14.

[0065] Next, the sixth manipulator position adjustment method will be explained using the flowchart in Figure 23. The sixth manipulator position adjustment method is used when the dimensions of the reference workpiece 13 are not precisely known, and the contact point Q6 cannot be measured due to reasons such as interference between at least one of the touch probe 8 and the tool base 2B with other structures, such as the end effector 11, or limitations on the operating range of the feed axis. Steps that overlap with the fifth manipulator position adjustment method shown in Figure 17 will not be explained in detail.

[0066] Figure 24 shows a schematic diagram of the positional relationship of the dimensional measurement position 16. After steps S51 and S52 are performed, in step S61, the manipulator 10 is positioned such that the reference workpiece 13 held by the end effector 11 is in a position and orientation different from the workpiece gripping preparation position 14 shown in Figure 24, for example, a position and orientation such as the dimension measurement position 16 shown in Figure 9 (fourth reference workpiece positioning step). In step S62, the tool rest 2B is moved so that the touch probe 8 contacts the reference workpiece 13 positioned at the dimensional measurement position 16, and the positions of multiple contact points on the reference workpiece 13 are measured, similar to step S54.

[0067] Figure 25 shows a schematic diagram of the measurement of the reference workpiece 13 at the dimensional measurement position 16. As shown in Figure 25, the touch probe 8 is moved in the Z-plus direction to make contact with a point on the side surface of the reference workpiece 13, and the contact point P11 (Xp11, zp11) is acquired (second machine tool position measurement step). Furthermore, the touch probe 8 is moved in the Z-minus direction to make contact, and the contact point P12 (Xp12, zp12) is acquired. Here, Xp11 and Xp12 are command values. In step S63, the dimensions of the reference workpiece 13 are calculated from the contact point positions obtained in step S62 (third reference object dimension measurement step). If the reference workpiece 13 is cylindrical, the diameter D can be calculated using the following equation (18). If the reference workpiece 13 is a square prism, the diameter D in equation (18) below can be replaced with the width D'. D = pz12 - pz11 (18)

[0068] Steps S53 to S59 are then performed in the same manner as the fifth manipulator position adjustment method. In the second manipulator position adjustment method, if the error in the position and orientation of the reference workpiece 13 is greater than the threshold in step S58, steps S53 to S59 are repeatedly executed until the error in the position and orientation of the reference workpiece 13 falls below the threshold, similar to the fifth manipulator position adjustment method. Steps S61 to S63 may be optionally included in this execution.

[0069] Next, the seventh manipulator position adjustment method will be explained using the flowchart in Figure 26. The seventh manipulator position adjustment method assumes that the workpiece gripping preparation position 14 has been adjusted at least once. Steps that overlap with the fifth manipulator position adjustment method shown in Figure 17 will not be explained in detail.

[0070] Figure 27 shows a schematic diagram of the positional relationship of the workpiece inspection position 15. After steps S51 and S52 are performed, in step S73, the manipulator 10 is positioned so that the reference workpiece 13, which is gripped by the end effector 11, is at the workpiece confirmation position 15, as shown in Figure 27 (third confirmation positioning step). Alternatively, the manipulator 10 may be positioned so that the reference workpiece 13 is at the workpiece gripping preparation position 14.

[0071] In step S74, similar to step S54, the tool rest 2B is moved so that the touch probe 8 contacts the reference workpiece 13, and the position of the contact point is determined (third machine tool position measurement step). Similar to step S54, step S74 is performed at predetermined locations. Step S74, the third machine tool position measurement step, is repeated until the completion of measurement at the predetermined locations is confirmed.

[0072] In step S75, the tool rest 2B is positioned so that the touch probe 8 is located near the workpiece confirmation position 15, similar to step S55 (second sensor positioning step). Alternatively, the tool rest 2B may be positioned near the workpiece gripping preparation position 14.

[0073] In step S76, similar to step S56, the manipulator 10 is moved to make contact with the touch probe 8 so that the reference workpiece 13 makes contact, and the position and orientation of the contact point are determined (second manipulator position measurement step). Step S76, the second manipulator position measurement step, is repeated until it is confirmed that the measurement has been completed at a predetermined location set in advance.

[0074] In step S77, the position and orientation of the reference workpiece 13 are calculated from the acquired contact point positions (second confirmation position calculation step). Note that, as in step S57, an error value may also be calculated in step S77. If the reference workpiece 13 is cylindrical, the inclination pAw about the X axis, the inclination pBw about the Y axis, the X position pXw of the base center, the Y position pYw of the base center, and the Z position pZw of the end face of the reference workpiece 13 can be calculated using the following equations (19) to (23). pAw = (yr4 - yr5) / (Zq5 - Zq4) (19) pBw = (xp3 - xp2) / (Zp3 - Zp2) (20) pZw = zr1 (21) pXw = xp2 - (yr4 + ycp - yr6 - ycn + d) / 2 (22) pYw = - (yr6 + ycn + yr4 + ycp) / 2 (23)

[0075] If the diameter of the reference workpiece 13 is precisely known as D, then, as described above, measurement of the contact point P6 is unnecessary, and the X position pXw of the center of the base can be determined by the following equation (24). Also, the Y position pYw of the center of the base can be determined by the following equation (25). pXw = xp2 - D / 2 (24) pYw = - (yr4 + ycp) + D / 2 (25)

[0076] If the reference workpiece 13 is a rectangular prism, the inclination pAw around the X axis, the inclination pBw around the Y axis, the X position pXw of the base center, the Y position pYw of the base center, and the Z position pZw of the end face can be calculated using the above equations (19) to (25), similar to the case of a cylindrical shape. However, the diameter D and assumed diameter value d in the above equations (19) to (25) are replaced with the width D' and assumed width dimension d', respectively. Furthermore, the inclination pCw around the Z-axis can be calculated using the following equation (26). pCw = (yr7 - yr2) / (Xq2 - Xq7) (26)

[0077] In step S78, it is determined whether the position and orientation of the reference workpiece 13, which were determined in step 77, are stored in memory. If steps S73 to S77 are performed for the first time immediately after adjusting the workpiece gripping preparation position 14, the position and orientation of the reference workpiece 13 are not stored. Therefore, in step S79, the position and orientation of the reference workpiece 13 are stored, and the position adjustment of the manipulator 10 is completed. If the position and orientation of the reference workpiece 13 are stored, in step S80, the difference between the calculated and stored values ​​of the position and orientation of the reference workpiece 13 is calculated as the amount of change in the position and orientation of the reference workpiece 13 (second position change amount calculation step).

[0078] In step S81, it is determined whether the amount of change calculated in step S80 is below a predetermined threshold. If the amount of change calculated in step S80 is below the threshold, the change is considered small, and the position adjustment of the manipulator 10 is terminated. At this point, the stored values ​​may be updated using the calculated position and orientation values ​​of the reference workpiece 13. On the other hand, if the amount of change calculated in step S80 is greater than the threshold, the position is corrected in step S59 (second confirmation position correction step). In this case, steps S59, S73-S78, and S80-S81 are repeatedly executed until the amount of change calculated in step S80 is below the threshold. The position adjustment of the manipulator 10 may be terminated after a certain number of repetitions.

[0079] Next, the method for adjusting the position of the eighth manipulator will be explained using the flowchart in Figure 28. In step S91, the touch probe 8 is attached to the tool bench 2B. In step S92, the manipulator 10 is made to grip the reference workpiece 13 with its end effector 11. Here, the reference workpiece 13 may be fixed to the end effector 11. Alternatively, an end effector 11 having a portion equivalent to the reference workpiece 13 may be used. In step S93, as shown in Figure 20, the tool rest 2B is positioned so that the touch probe 8 is located at the workpiece gripping preparation position 14 (third sensor positioning step).

[0080] In step S94, the manipulator 10 is moved so that the reference workpiece 13, held by the end effector 11, contacts the touch probe 8 positioned at the workpiece gripping preparation position 14. The signal output by the touch probe 8 detecting contact is received not by the machine tool 1, but by the numerical control device NC2. Subsequently, the numerical control device NC2 of the manipulator 10 acquires the position of each joint drive axis at the time the signal is received or at a time considering the delay. Based on the acquired joint drive axis positions, the numerical control device NC2 performs calculations that take into account forward kinematics calculations, deformation errors due to gravity, and preset correction values ​​to determine the position and orientation of the manipulator 10 at the contact point (third manipulator position measurement step). Step S94, the third manipulator position measurement step, is repeatedly executed until the completion of measurement at a predetermined location is confirmed.

[0081] Regarding steps S93 and S94, the case where the reference workpiece 13 is cylindrical will be explained. Figure 29 is a schematic diagram of the measurement position of the cylindrical reference workpiece 13 at the workpiece gripping preparation position 14, and is an explanatory diagram of moving the reference workpiece 13 in the Z-axis direction. If the reference workpiece 13 is cylindrical, as shown in Figure 29, in step S93, the touch probe 8 is positioned at Q1 (Xq1, Zq1) on the cylindrical bottom surface of the workpiece gripping preparation position 14. Then, in step S94, the reference workpiece 13 is moved in the Z-minus direction to make contact with the touch probe 8, and the three positional components and three orientation components of the contact point at Q1, Q1r (xr1, yr1, zr1, ar1, br1, cr1), are determined from the joint drive axis positions of the manipulator 10.

[0082] Furthermore, steps S93 and S94 are performed at a total of six locations: two in the X-positive direction, two in the Y-negative direction, and one in the Y-positive direction, as shown below. Figure 30 is a schematic diagram of the measurement position of a cylindrical reference workpiece at the workpiece gripping preparation position 14, and is an explanatory diagram of moving the reference workpiece 13 in the X-axis direction. As shown in Figure 30, in step S93, the touch probe 8 is positioned at Q2 (Xq2, Zq2) and Q3 (Xq3, Zq3) in the X-plus direction on the cylindrical side surface of the workpiece gripping preparation position 14. Subsequently, in S94, when the touch probe 8 is positioned at positions Q2 and Q3, the reference workpiece 13 is moved in the X-plus direction to bring the touch probe 8 into contact with the side surface of the reference workpiece 13, and the position and orientation of the contact point Q2r (xr2, yr2, zr2, ar2, br2, cr2) for Q2 and Q3r (xr3, yr3, zr3, ar3, br3, cr3) for Q3 are obtained.

[0083] Furthermore, as shown in Figure 21, in step S93, the touch probe 8 is positioned at Q4 (Xq4, Zq4) on the central axis w of the cylinder at the workpiece gripping preparation position 14. Subsequently, in step S94, the reference workpiece 13 is moved in the Y-minus and Y-plus directions respectively, and the touch probe 8 is brought into contact with the side surface of the reference workpiece 13, thereby obtaining the position and orientation Q4r (xr4, yr4, zr4, ar4, br4, cr4) of the contact point in the Y-plus direction and the position and orientation Q6r (xr6, yr6, zr6, ar6, br6, cr6) of the contact point in the Y-minus direction. Furthermore, in step S93, the touch probe 8 is positioned at Q5 (Xq5, Zq5) on the central axis w of the cylinder at the workpiece gripping preparation position 14. Subsequently, in step S94, the reference workpiece 13 is moved in the Y-minus direction and the touch probe 8 is brought into contact with the side surface of the reference workpiece 13, and the position and orientation Q5r (xr5, yr5, zr5, ar5, br5, cr5) of the contact point relative to Q5 is obtained. Here, if the diameter D of the reference workpiece 13 is known precisely, the measurement of Q6r does not need to be performed.

[0084] Furthermore, if the reference workpiece 13 is a square prism shape, measurements are taken at a total of seven locations, as shown in Figure 22: one location on the Z-minus direction plane, two locations on the X-plus direction plane, three locations on the Y-minus direction plane, and one location on the Y-plus direction plane. However, Q4 is a position offset in the X-plus direction from the central axis W' of the square prism, and Q7 is a position offset in the X-minus direction. The measurement at Q7 obtains the position and orientation Q7r(xr7,yr7,zr7,ar7,br7,cr7) of the contact point. Similar to the case of a cylindrical shape, if the width D' of the reference workpiece 13 is known precisely, measurement of Q6r does not need to be performed.

[0085] Next, in step S95, the positional and orientation errors of the reference workpiece 13 are calculated (third reference object position error calculation step). If the reference workpiece 13 is cylindrical, the tilt error dAw of the reference workpiece 13 around the X axis can be calculated using the following formula (27). Also, the tilt error dBw around the Y axis can be calculated using the following formula (28). dAw = (yr4 - yr5) / (Zq5 - Zq4) (27) dBw = (xr2 - xr3) / (Zq3 - Zq2) (28)

[0086] Furthermore, the X-direction error dXw at the center of the bottom surface of the reference workpiece 13 is calculated using the following equation (29). Also, the Y-direction error dYw at the center of the bottom surface of the reference workpiece 13 is calculated using the following equation (30). Here, xcn is the correction value in the negative X direction, ycp is the correction value in the positive Y direction, and ycn is the correction value in the negative Y direction. xcn, ycp, and ycn are used to correct errors such as the radius and misalignment of the stylus sphere of the touch probe 8. Also, d is the assumed diameter value of the reference workpiece 13 for calculating the contact point in the manipulator 10. dXw = - (xr2 - Xq2 + xcn) - (yr4 + ycp - yr6 - ycn + d) / 2 (29) dYw = - (yr6 + ycn + yr4 + ycp) / 2 (30)

[0087] If the diameter D of the reference workpiece 13 is known precisely, measurement of the orientation Q6r is unnecessary, and the X-direction error dXw of the center of the bottom surface of the reference workpiece 13 can be calculated using the following equation (31). Also, the Y-direction error dYw of the center of the bottom surface of the reference workpiece 13 can be calculated using the following equation (32). dXw = - (xr2 - Xq2 + xcn) - D / 2 (31) dYw = - (yr4 - Yq4 + ycp) + D / 2 (32)

[0088] Furthermore, the Z-direction error dZw of the end face of the reference workpiece 13 can be calculated using the following equation (33). Here, zcp is a correction value in the Z-positive direction, and is used, for example, to correct the Z-positive error of the touch probe 8. dZw = zr1 - Zq1 + zcp (33)

[0089] If the reference workpiece 13 is a square prism shape, then, in the same way as in the case of a cylindrical shape, the X-direction error dXw of the center of the base of the reference workpiece 13, the Y-direction error dYw of the center of the base of the reference workpiece 13, the Z-direction error dZw of the end face, the tilt error dAw around the X axis, and the tilt error dBw around the Y axis can be calculated using the above equations (27) to (33). However, the diameter D and assumed diameter value d in the above equations (27) to (33) are replaced with the width D' and assumed width dimension d', respectively. Furthermore, the tilt error dCw around the Z axis can be calculated using the following equation (34). dCw = (yr7 - yr4) / (Xq4 - Xq7) (34)

[0090] In step S96, it is determined whether the errors in the position and orientation of the reference workpiece 13, which were determined in step S95, are below a predetermined threshold. If they are below the threshold, the errors are considered small, and the position adjustment of the manipulator 10 is completed. On the other hand, if the error in the position and orientation of the reference workpiece 13 is greater than the threshold, correction is performed in step S97. In this case, steps S93 to S97 are repeatedly executed until the error in the position and orientation of the reference workpiece 13 falls below the threshold. Note that the position adjustment of the manipulator 10 may be terminated after a certain number of repetitions.

[0091] In step S97, the position and orientation commands of the end effector 11 are corrected to cancel out the position and orientation errors of the reference workpiece 13 obtained in step S95 (third manipulator position correction step). One correction method is to set a local coordinate system when teaching the workpiece gripping preparation position 14 of the manipulator 10 and correct that local coordinate system. Another method is to correct the teaching data when teaching the workpiece gripping preparation position 14.

[0092] Next, the ninth manipulator position adjustment method will be explained using the flowchart in Figure 32. The ninth manipulator position adjustment method is used when the dimensions of the reference workpiece 13 are not precisely known, and the contact point P6 cannot be measured due to limitations in the operating range of the feed axis, such as interference between at least one of the touch probe 8 and the tool base 2B with other structures, such as the end effector 11. In the ninth manipulator position adjustment method, the tool base 2B is positioned so that the touch probe 8 is located in the position shown in Figure 24. However, detailed explanations of steps that overlap with the eighth manipulator position adjustment method shown in Figure 28 will be omitted.

[0093] After steps S91 and S92 are performed, in step S101, the tool rest 2B is positioned so that the touch probe 8 is located at a touch probe dimension measurement position, which is a different position and orientation from the workpiece gripping preparation position 14, as shown in Figure 24 (fourth sensor positioning step). In step S102, the manipulator 10 is moved so that the reference workpiece 13 held by the end effector 11 makes contact with the touch probe 8 positioned at the touch probe dimension measurement position, and the position and orientation of the contact point are determined in the same way as in step S94 (fourth manipulator position measurement step). Step S102, the fourth manipulator position measurement step, is repeatedly performed until it is confirmed that the measurement has been completed at a predetermined location.

[0094] As shown in Figure 31, the touch probe 8 is positioned at the touch probe dimension measurement position Q11 (Xq11, Zq11). Subsequently, the reference workpiece 13 is moved in the Z-plus and Z-minus directions respectively, and the touch probe 8 is brought into contact with the side surface of the reference workpiece 13, thereby obtaining the position and orientation Q11r (xr11, yr11, zr11, ar11, br11, cr11) of the Z-plus contact point relative to Q11 and the position and orientation Q12r (xr12, yr12, zr12, ar12, br12, cr12) of the Z-minus contact point. Subsequently, in step S103, the dimensions of the reference workpiece 13 are calculated from the contact point position and orientation obtained in step S102 (fifth reference object dimension measurement step).

[0095] If the reference workpiece 13 is cylindrical, the diameter D is calculated using the following equation (35). If the reference workpiece 13 is a square prism, D in equation (35) is replaced with the width D' of the reference workpiece 13. Here, zcn is a correction value in the Z-minus direction, and is used, for example, to correct the error of the touch probe 8 in the Z-minus direction. D = zr11 + zcp - zr12 - zcn + d (35)

[0096] Steps S93 to S97 are repeatedly executed until the threshold is met in step S96, but steps S101 to S103 may be optionally included in this execution.

[0097] Next, the method for adjusting the position of the tenth manipulator will be explained using the flowchart in Figure 33. The method for adjusting the position of the tenth manipulator assumes that the workpiece gripping preparation position 14 has been adjusted at least once. However, detailed explanations of the same steps as those for adjusting the position of the eighth manipulator shown in Figure 28 will be omitted.

[0098] After steps S91 and S92 are performed, in step S113, the tool rest 2 is positioned so that the touch probe 8 is located at the workpiece confirmation position 15, which is near the workpiece gripping preparation position 14, similar to step S93 (fifth sensor positioning step).

[0099] In step S114, the manipulator 10 is moved to make contact with the touch probe 8 positioned at the workpiece confirmation position 15, so that the reference workpiece 13 held by the end effector 11 makes contact, similar to step S94, and the position and orientation of the contact point are determined (fifth manipulator position measurement step). Step S114, which is the fifth manipulator position measurement step, is repeatedly performed until it is confirmed that the measurement has been completed at a predetermined location set in advance.

[0100] In step S115, the position and orientation of the reference workpiece 13 are calculated from multiple contact point positions obtained by performing steps S113 and S114 at predetermined locations (third confirmation position calculation step). Note that, similar to step S95, an error value may also be calculated in step S115. If the reference workpiece 13 is cylindrical, the inclination pAw about the X axis, the inclination pBw about the Y axis, the X position pXw of the base center, the Y position pYw of the base center, and the Z position pZw of the end face of the reference workpiece 13 can be calculated using the following equations (36) to (39). pAw = (yr4 - yr5) / (Zq5 - Zq4) (36) pBw = (xr2 - xr3) / (Zq3 - Zq2) (37) pZw = zr² + zcp (38) pXw = - (xr2 + xcn) - (yr4 + ycp - yr6 - ycn + d) / 2 (39) pYw = - (yr6 + ycn + yr4 + ycp) / 2 (40)

[0101] If the diameter D of the reference workpiece 13 is known precisely, measurement of the contact point P6 is unnecessary, and the X position pXw of the center of the base can be determined by the following equation (41). Also, the Y position pYw of the center of the base can be determined by the following equation (42). pXw = - (xr2 + xcn) - D / 2 (41) pYw = - (yr4 + ycp) + D / 2 (42)

[0102] If the reference workpiece 13 is a regular square prism, the inclination pAw about the X axis, the inclination pBw about the Y axis, the X position pXw of the base center, the Y position pYw of the base center, and the Z position pZw of the end face can be calculated using the above equations (36) to (40), similar to the case of a cylindrical shape. However, the diameter D and assumed diameter value d in the above equations (36) to (40) are replaced with the width D' and assumed width dimension d', respectively. Furthermore, the inclination pCw around the Z-axis can be calculated using the following equation (43). pCw = (yr7 - yr4) / (Xq4 - Xq7) (43)

[0103] In step S116, it is determined whether the position and orientation of the reference workpiece 13, which were determined in step S115, are stored in memory. If steps S113 to S115 are performed for the first time immediately after adjusting the workpiece gripping preparation position 14, the position and orientation of the reference workpiece 13 are not stored. Therefore, in step S119, the position and orientation of the reference workpiece 13 are stored, and the position adjustment of the manipulator 10 is completed. If the position and orientation of the reference workpiece 13 are stored, in step S117, the difference between the calculated and stored values ​​of the position and orientation of the reference workpiece 13 is calculated as the amount of change in the position and orientation of the reference workpiece 13 (third position change amount calculation step).

[0104] In step S118, it is determined whether the amount of change calculated in step S117 is below a predetermined threshold. If the amount of change calculated in step S117 is below the threshold, the change is considered small, and the position adjustment of the manipulator 10 is terminated. The stored values ​​may be updated using the calculated position and orientation values ​​of the reference workpiece 13. On the other hand, if the amount of change calculated in step S117 is greater than the threshold, the position is corrected in step S97 (third confirmation position correction step). In this case, steps S97, S113 to S117 are repeatedly executed until the amount of change calculated in step S117 is below the threshold. The position adjustment of the manipulator 10 may be terminated after a certain number of repetitions.

[0105] In the above embodiment, the position of the manipulator 10 was described as being corrected by measuring the position or orientation of the reference workpiece 13, but the present disclosure may also be implemented using a workpiece 12 instead of the reference workpiece 13. Furthermore, the threshold values ​​for the error in the position and orientation of the reference workpiece, as well as the threshold values ​​for the amount of change, are set in advance from various information acquired beforehand and stored in the numerical control device. The numerical control device may control both the machine tool and the manipulator in a single unit. [Explanation of symbols]

[0106] 1. Machine tool, 1a. Two-axis horizontal lathe (machine tool), 2A, 2B. Tool stand, 3. Turning spindle, 4. Chuck, 5. Second turning spindle, 6. Chuck, 7. Tool, 8. Touch probe (contact sensor), 10. Manipulator, 11. End effector, 12. Workpiece, 13. Reference workpiece (reference object), 14. Workpiece gripping preparation position, 15. Workpiece confirmation position, 20. Workpiece stocker, 30. Machining cell.

Claims

1. A machine tool comprising a chuck capable of gripping a workpiece, a tool rest on which a tool can be mounted, and three or more translational drive shafts that enable translational motion of the tool rest, In a machining system comprising a manipulator having an end effector capable of gripping the workpiece and a plurality of joint drive axes, A method for adjusting the position of a manipulator, which adjusts the position or orientation of the end effector at a workpiece gripping position where the workpiece gripped by the end effector is held by the chuck, A first reference object positioning step involves positioning the manipulator such that a reference object having a specific shape, which is gripped or fixed to the end effector, is located at a workpiece gripping preparation position near the workpiece gripping position. A first reference object position measurement step involves mounting a contact-type sensor on the tool stand, moving the tool stand so that the contact-type sensor makes contact with the reference object positioned in the first reference object positioning step, obtaining the position of the translational drive shaft at the time the contact-type sensor detects contact, and calculating the contact point position from the obtained translational drive shaft position. A first reference object position error calculation step calculates an error in the position or orientation of the reference object gripped or fixed to the end effector from a plurality of contact point positions obtained by performing the first reference object position measurement step on a plurality of locations of the reference object, and command values ​​for the position and orientation of the end effector in the first reference object positioning step, A first manipulator position correction step, which corrects the position or orientation of the end effector so as to cancel out the position or orientation error of the reference object calculated in the first reference object position error calculation step, A method for adjusting the position of a manipulator, characterized by performing the following.

2. A second reference object positioning step involves positioning the manipulator so that the reference object, which is gripped or fixed to the end effector, is in a different position or orientation than that of the first reference object positioning step. A second reference object position measurement step involves moving the tool rest so that the contact sensor mounted on the tool rest makes contact with the reference object gripped or fixed to the end effector that was positioned in the second reference object positioning step, obtaining the position of the translational drive shaft at the time the contact sensor detects contact, and calculating the contact point position from the obtained position of the translational drive shaft. A first reference object dimension measurement step calculates the dimensions of the reference object from a plurality of contact point positions obtained by performing the second reference object position measurement step on a plurality of locations of the reference object, Further execution, In the first reference object position error calculation step, the reference object dimensions calculated in the first reference object dimension measurement step are used to calculate the error in the position or orientation of the reference object gripped or fixed to the end effector. The method for adjusting the position of a manipulator according to feature 1.

3. The manipulator position adjustment method according to claim 1 or 2, characterized in that if the error in the position or orientation of the reference object calculated in the first reference object position error calculation step is greater than or equal to a predetermined threshold, the steps from the first reference object positioning step to the first manipulator position correction step are repeated.

4. A machine tool comprising a chuck capable of gripping a workpiece, a tool rest on which a tool can be mounted, and three or more translational drive shafts that enable translational motion of the tool rest, In a machining system comprising a manipulator having an end effector capable of gripping the workpiece and a plurality of joint drive axes, A method for adjusting the position of a manipulator, which adjusts the position or orientation of the end effector at a workpiece gripping position where the workpiece gripped by the end effector is held by the chuck, A first confirmation and positioning step involves positioning the manipulator so that a reference object having a specific shape, which is gripped or fixed to the end effector, is located at a preset workpiece confirmation position. A first confirmation measurement step involves mounting a contact-type sensor on the tool stand, moving the tool stand so that the contact-type sensor makes contact with the reference object positioned in the first confirmation positioning step, obtaining the position of the translational drive shaft at the time the contact-type sensor detects contact, and calculating the contact point position from the obtained position of the translational drive shaft. A first confirmation position calculation step calculates the position or orientation of the reference object gripped or fixed to the end effector from a plurality of contact point positions obtained by performing the first confirmation measurement step on a plurality of locations of the reference object, A first position change amount calculation step calculates the amount of change in the position or orientation of the reference object from the calculated value of the position or orientation of the reference object calculated in the first confirmation position calculation step and the stored value of the position or orientation of the reference object that has been measured and stored in advance. A first confirmation position correction step is performed to correct the position or orientation of the end effector so as to cancel out the amount of change calculated in the first position change calculation step, A method for adjusting the position of a manipulator, characterized by performing the following.

5. A second confirmation positioning step involves positioning the manipulator so that the reference object, which is gripped or fixed to the end effector, is in a different position or orientation than that of the first confirmation positioning step. A second confirmation position measurement step involves moving the tool rest so that the contact sensor mounted on the tool rest makes contact with the reference object gripped or fixed to the end effector positioned in the second confirmation position step, obtaining the position of the translational drive shaft at the time the contact sensor detects contact, and calculating the contact point position from the obtained position of the translational drive shaft. A second reference object dimension measurement step is performed, which involves calculating the dimensions of the reference object from a plurality of contact point positions obtained by performing the second confirmation position measurement step on a plurality of locations of the reference object. The manipulator position adjustment method according to claim 4, characterized in that, in the first confirmation position calculation step, the position or orientation of the reference object gripped or fixed to the end effector is calculated using the dimensions of the reference object measured in the second reference object dimension measurement step.

6. The manipulator position adjustment method according to claim 4 or 5, characterized in that if the amount of change calculated in the first position change amount calculation step is greater than or equal to a predetermined threshold, the steps from the first confirmation position step to the first confirmation position correction step are repeated.

7. A machine tool comprising a chuck capable of gripping a workpiece, a tool rest on which a tool can be mounted, and a translational drive shaft for translating the tool rest, wherein the translational motion of the tool rest has two or fewer degrees of freedom, In a machining system comprising a manipulator having an end effector capable of gripping the workpiece and a plurality of joint drive axes, A method for adjusting the position of a manipulator, which adjusts the position or orientation of the end effector at a workpiece gripping position where the workpiece gripped by the end effector is held by the chuck, A third reference object positioning step involves positioning the manipulator such that a reference object having a specific shape, which is gripped or fixed to the end effector, is located at a workpiece gripping preparation position near the workpiece gripping position. A first machine tool position measurement step involves moving the tool rest so that a contact sensor mounted on the tool rest contacts the reference object positioned in the third reference object positioning step, acquiring the position of the translational drive shaft at the time the contact sensor detects contact, and calculating the machine tool contact point position from the acquired position of the translational drive shaft. A first sensor positioning step involves positioning the tool rest so that a contact-type sensor mounted on the tool rest is positioned in the workpiece gripping preparation position, A first manipulator position measurement step involves moving the end effector so that the reference object gripped or fixed to the end effector contacts the contact sensor positioned in the first sensor positioning step, obtaining the position of the joint drive axis at the time the contact sensor detects contact, and calculating the manipulator contact point position from the obtained position of the joint drive axis. A second reference object position error calculation step calculates an error in the position or orientation of the reference object gripped or fixed to the end effector at the workpiece gripping preparation position, based on the command values ​​of the position and orientation of the end effector in the third reference object positioning step, the multiple machine tool contact point positions obtained by performing the first machine tool position measurement step on multiple locations of the reference object, the command values ​​of the positions of multiple tool rests when the first sensor positioning step is performed at multiple positions of the workpiece gripping preparation position, and the multiple manipulator contact point positions obtained by performing the first manipulator position measurement step at multiple positions of the workpiece gripping preparation position. A second manipulator position correction step, which corrects the position or orientation of the end effector so as to cancel out the position or orientation error of the reference object calculated in the second reference object position error calculation step, A method for adjusting the position of a manipulator, characterized by performing the following.

8. A fourth reference object positioning step involves positioning the manipulator so that the reference object, which is gripped or fixed to the end effector, is in a different position or orientation than that of the third reference object positioning step. A second machine tool position measurement step involves moving the tool rest so that the contact sensor mounted on the tool rest makes contact with the reference object positioned in the fourth reference object positioning step, obtaining the position of the translational drive shaft at the time the contact sensor detects contact, and calculating the machine tool contact point position from the obtained position of the translational drive shaft. A third reference object dimension measurement step is performed, which calculates the dimensions of the reference object from the multiple machine tool contact point positions obtained by performing the second machine tool position measurement step on multiple locations of the reference object. In the second reference object position error calculation step, the reference object dimensions obtained in the third reference object dimension measurement step are used to calculate the error in the position or orientation of the reference object gripped or fixed to the end effector. The method for adjusting the position of a manipulator according to feature 7.

9. The manipulator position adjustment method according to claim 7 or 8, characterized in that if the error in the position or orientation of the reference object calculated in the second reference object position error calculation step is greater than or equal to a predetermined threshold, the steps from the third reference object positioning step to the second manipulator position correction step are repeated.

10. A machine tool comprising a chuck capable of gripping a workpiece, a tool rest on which a tool can be mounted, and a translational drive shaft for translating the tool rest, wherein the translational motion of the tool rest has two or fewer degrees of freedom, In a machining system comprising a manipulator having an end effector capable of gripping the workpiece and a plurality of joint drive axes, A method for adjusting the position of a manipulator, which adjusts the position or orientation of the end effector at a workpiece gripping position where the workpiece gripped by the end effector is held by the chuck, A third confirmation and positioning step involves positioning the manipulator so that a reference object having a specific shape, which is gripped or fixed to the end effector, is located at a workpiece confirmation position different from the workpiece gripping position. A third machine tool position measurement step involves moving the tool stand so that a contact sensor mounted on the tool stand makes contact with the reference object positioned in the third confirmation positioning step, acquiring the position of the translational drive shaft at the time the contact sensor detects contact, and calculating the machine tool contact point position from the acquired position of the translational drive shaft. A second sensor positioning step involves positioning the tool rest so that a contact-type sensor mounted on the tool rest is positioned at the workpiece confirmation position, A second manipulator position measurement step involves moving the end effector so that the reference object gripped or fixed to the end effector contacts the contact sensor positioned in the second sensor positioning step, obtaining the position of the joint drive axis at the time the contact sensor detects contact, and calculating the manipulator contact point position from the obtained position of the joint drive axis. A second confirmation position calculation step calculates the position or orientation of the reference object gripped or fixed to the end effector at the workpiece confirmation position from the command values ​​of the position and orientation of the end effector in the third confirmation position step, the multiple machine tool contact point positions obtained by performing the third machine tool position measurement step on multiple locations of the reference object, the command values ​​of the positions of multiple tool rests when the second sensor positioning step is performed at multiple locations of the workpiece confirmation position, and the multiple manipulator contact point positions obtained by performing the second manipulator position measurement step at multiple locations of the workpiece confirmation position, A second position change amount calculation step calculates the amount of change in the position or orientation of the reference object from the calculated value of the position or orientation of the reference object calculated in the second confirmation position calculation step and the stored value of the position or orientation of the reference object that has been measured and stored in advance. A second confirmation position correction step is performed to correct the position or orientation of the end effector so as to cancel out the amount of change calculated in the second position change calculation step, A method for adjusting the position of a manipulator, characterized by performing the following.

11. The manipulator position adjustment method according to claim 10, characterized in that if the amount of change in the position or orientation of the reference object calculated in the second position change amount calculation step is greater than or equal to a predetermined threshold, the steps from the third confirmation positioning step to the second confirmation position correction step are repeated.

12. A machine tool comprising a chuck capable of gripping a workpiece, a tool rest on which a tool can be mounted, and a translational drive shaft for translating the tool rest, In a machining system comprising a manipulator having an end effector capable of gripping the workpiece and a plurality of joint drive axes, A method for adjusting the position of a manipulator, which adjusts the position or orientation of the end effector at a workpiece gripping position where the workpiece gripped by the end effector is held by the chuck, A third sensor positioning step involves positioning the tool rest so that a contact-type sensor mounted on the tool rest is located at a workpiece gripping preparation position near the workpiece gripping position, A third manipulator position measurement step involves moving the end effector so that a reference object gripped or fixed to the end effector contacts the contact sensor positioned in the third sensor positioning step, obtaining the position of the joint drive axis at the time the contact sensor detects contact, and calculating the contact point position from the obtained position of the joint drive axis. A third reference object position error calculation step calculates an error in the position or orientation of the reference object gripped or fixed to the end effector at the workpiece gripping preparation position, based on command values ​​of the positions of multiple tool rests when the third sensor positioning step is performed at multiple positions of the workpiece gripping preparation position, and multiple contact point positions obtained by performing the third manipulator position measurement step at multiple positions of the workpiece gripping preparation position. A third manipulator position correction step, which corrects the position or orientation of the end effector so as to cancel out the position or orientation error of the reference object calculated in the third reference object position error calculation step, A method for adjusting the position of a manipulator, characterized by performing the following.

13. A fourth sensor positioning step involves positioning the tool rest so that the contact sensor mounted on the tool rest is located at a dimensional measurement position different from the workpiece gripping preparation position, A fourth manipulator position measurement step involves moving the end effector so that the reference object gripped or fixed to the end effector comes into contact with the contact sensor positioned in the fourth sensor positioning step, obtaining the position of the joint drive axis at the time the contact sensor detects contact, and calculating the contact point position from the obtained position of the joint drive axis. A fifth reference object dimension measurement step is performed, which calculates the dimensions of the reference object from the multiple contact point positions obtained by performing the fourth manipulator position measurement step on multiple locations of the reference object. In the third reference object position error calculation step, the error in the position or orientation of the reference object held or fixed to the end effector is calculated using the reference object dimensions obtained in the fifth reference object dimension measurement step. The method for adjusting the position of a manipulator according to feature 12.

14. The manipulator position adjustment method according to claim 12 or 13, characterized in that if the error in the position or orientation of the reference object calculated in the third reference object position error calculation step is greater than or equal to a predetermined threshold, the steps from the third sensor positioning step to the third manipulator position correction step are repeated.

15. The method for adjusting the position of a manipulator according to claim 12 or 13, characterized in that the degree of freedom of the translational motion of the tool stand is two or less.

16. A machine tool comprising a chuck capable of gripping a workpiece, a tool rest on which a tool can be mounted, and a translational drive shaft for translating the tool rest, In a machining system comprising a manipulator having an end effector capable of gripping the workpiece and a plurality of joint drive axes, A method for adjusting the position of a manipulator, which adjusts the position or orientation of the end effector at a workpiece gripping position where the workpiece gripped by the end effector is held by the chuck, A fifth sensor positioning step involves positioning the tool rest so that a contact-type sensor mounted on the tool rest is located at a workpiece confirmation position different from the workpiece gripping position. A fifth manipulator position measurement step involves moving the end effector so that a reference object gripped or fixed to the end effector contacts the contact sensor positioned in the fifth sensor positioning step, obtaining the position of the joint drive axis at the time the contact sensor detects contact, and calculating the contact point position from the obtained position of the joint drive axis. A third confirmation position calculation step calculates the position or orientation of the reference object held by the end effector from the command values ​​of the positions of the multiple tool rests when the fifth sensor positioning step is performed at multiple positions of the workpiece confirmation position, and the multiple contact point positions obtained by performing the fifth manipulator position measurement step at multiple positions of the workpiece confirmation position, A third position change amount calculation step calculates the amount of change in the position or orientation of the reference object from the calculated value of the position or orientation of the reference object calculated in the third confirmation position calculation step and the stored value of the position or orientation of the reference object that has been measured and stored in advance. A third confirmation position correction step is performed to correct the position or orientation of the end effector so as to cancel out the amount of change calculated in the third position change calculation step, A method for adjusting the position of a manipulator, characterized by performing the following.

17. The manipulator position adjustment method according to 16, characterized in that if the amount of change in the position or orientation of the reference object calculated in the third position change amount calculation step is greater than or equal to a predetermined threshold, the steps from the fifth sensor positioning step to the third confirmation position correction step are repeated.

18. The method for adjusting the position of a manipulator according to claim 16 or 17, characterized in that the degree of freedom of the translational motion of the tool stand is two or less.

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