Method for calibrating a robot

Abstract

A method for calibrating a robot is disclosed. A working space of the robot at least partly overlaps with a working space of a machining and/or production tool. The robot is moved such that a reference point of the robot is at a first position within the working space of the machining and/or production tool. A first position value for the robot at the first position is compared with a first position value for the machining and/or production tool at the position. If the first position value for the robot differs from the first position value for the machining and/or production tool, the first position value for the robot is corrected or the first position value for the machining and/or production tool is corrected such that the first position value for the robot and the first position value for the machining and/or production tool are the same.

Claims

1. A method for calibrating a robot, the method comprising: moving a robot such that a reference point of the robot is located at a first position within a working space of the machine tool and/or production machine; comparing a first position value for the robot at the first position with a first position value for the machine tool and/or production machine at the first position; and based on the comparing, when the first position value for the robot differs from the first position value for the machine tool and/or production machine, the first position value for the robot is corrected, or the first position value for the machine tool and/or production machine is corrected, such that the first position value for the robot and the first position value for the machine tool and/or production machine are the same, wherein a working space of the robot at least partially overlaps a working space of the machine tool and/or the production machine.

2. The method of claim 1, wherein the first position values have a first coordinate, a second coordinate, and a third coordinate.

3. The method of claim 1, further comprising: moving the robot such that the reference point of the robot is located at a second position within the working space of the machine tool and/or production machine; comparing a second position value for the robot at the second position with a second position value for the machine tool and/or production machine at the second position; and based on the comparing, when the second position value for the robot differs from the second position value for the machine tool and/or production machine, the second position value for the robot is corrected or the second position value for the machine tool and/or production machine is corrected such that the second position value for the robot and the second position value for the machine tool and/or production machine are the same.

4. The method of claim 3, further comprising ascertaining a third position value by interpolation or extrapolation based on the corrected first position value for the robot or for the machine tool and/or production machine and the corrected second position value for the robot or the machine tool and/or production machine.

5. The method of claim 1, further comprising moving the robot such that the reference point of the robot is located at a plurality of positions within the working space of the machine tool and/or production machine.

6. The method of claim 5, wherein the plurality of positions are arranged in a grid-like manner and/or in an array-like manner or wherein the plurality of positions are arranged such that the positions are located at or close to critical points of a workpiece to be machined.

7. The method of claim 1, wherein the reference point of the robot is arranged at an end effector of the robot.

8. The method of claim 1, further comprising moving the robot such that the reference point of the robot is located at a position on a worktable of the machine tool and/or production machine.

9. The method of claim 8, wherein the position on the worktable is in a corner of the worktable of the machine tool and/or production machine.

10. The method of claim 1, further comprising moving the robot such that the reference point of the robot is located at a spindle of the machine tool and/or production machine.

11. The method of claim 10, further comprising detecting contact with the worktable and/or the spindle is detected by a sensor probe present on and/or in an end effector of the robot.

12. The method of claim 10, further comprising detecting contact with the spindle by a sensor probe present on and/or in the spindle.

13. A system, comprising: a robot; a machine tool and/or production machine arranged such that a working space of the robot at least partially overlaps a working space of the machine tool and/or production machine; and a controller configured to move the robot such that a reference point of the robot is located at a first position within the working space of the machine tool and/or production machine; compare a first position value for the robot at the first position with a first position value for the machine tool and/or production machine at the first position; and based on the comparing, when the first position value for the robot differs from the first position value for the machine tool and/or production machine, correct the first position value for the robot, or correct the first position value for the machine tool and/or production machine, such that the first position value for the robot and the first position value for the machine tool and/or production machine are the same.

14. The system of claim 13, wherein the machine tool and/or production machine has a sensor probe and the machine tool and/or production machine is configured to function as a measuring tool.

15. The system of claim 14, wherein the machine tool and/or production machine has a spindle and the sensor probe is present on and/or in the spindle.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The following describes and explains the invention in more detail with reference to the exemplary embodiments depicted in the figures, in which:

(2) FIG. 1 shows a system having a robot and a machine tool and/or production machine,

(3) FIG. 2 shows a first possible embodiment,

(4) FIG. 3 shows a second possible embodiment,

(5) FIG. 4 shows the method according to the invention,

(6) FIG. 5 shows, by way of example, a working space of the robot and a working space of the machine tool and/or production machine,

(7) FIG. 6 and FIG. 7 show, by way of example, an assignment of numerical controls.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(8) FIG. 1 shows a system 10 having a robot 2 and a machine tool and/or production machine 4.

(9) The robot 2 and the machine tool and/or production machine 4 are arranged such that a working space of the robot AR (see FIG. 5) and a working space of the machine tool and/or production machine AW at least partially overlap (see FIG. 5).

(10) FIG. 1 further shows a workpiece 6, a tool center point (TCP) 12 of the robot.

(11) A tool position of the robot 2 is described via its end effector. This is an imaginary reference point located at a suitable point on the tool. The reference point according to claim 1 is advantageously the TCP 12.

(12) FIG. 1 also shows a display 16 of the machine tool and/or production machine 4. FIG. 1 shows that the workpiece 6 has already been machined in the region 18.

(13) Machining of a workpiece 6 is achieved by cooperation between the machine tool and/or production machine 4 and the robot 2. For example, the machine tool and/or production machine 4 can be used to machine and join a workpiece 6.

(14) The robot 2 can, for example, position the workpiece 6. The robot 2 can also be embodied for cleaning, deburring and/or polishing. The robot 2 can also perform other tasks.

(15) The workpiece 6 can be machined simultaneously by the machine tool and/or production machine 4 and robot 2.

(16) However, so-called joint machining with which the workpiece 6 is machined alternately by the machine tool and/or production machine 4 and the robot 2. However, simultaneous machining is also possible.

(17) The machine tool and/or the production machine 4 is more accurate than the robot 2. A machine tool and/or production machine 4 is often at least one order of magnitude more accurate.

(18) The robot 2 has, for example, an accuracy, in particular static accuracy, of approximately 1 mm, that of the machine tool and/or production machine 4 is approximately 10 m.

(19) The invention offers the advantage that the accuracy of the robot 2 in the region of the working space of the machine tool and/or production machine 4 can be increased, in particular a relative accuracy of the robot 2 in relation to the machine tool and/or production machine 4 can be significantly increased.

(20) In this case, a slight deterioration in the accuracy of the robot 2 that may occur outside the overlapping working space of the machine tool and/or production machine 4 and the robot 2 can be quite acceptable.

(21) Advantageously, the more accurate machine tool and/or production machine 4 serves as a measuring standard for the less accurate robot 2.

(22) The system 10 shown in FIG. 1 shows a possible arrangement of the machine tool and/or production machine 4 and the robot 2. In this case, the robot 2 is arranged with respect to the machine tool and/or production machine 4 such that the two working spaces at least partially overlap.

(23) However, a method outside this common working space is also possible by means of the robot 2 and the machine tool and/or production machine 4.

(24) A plurality of points whose position is precisely known are available within the working space of the machine tool and/or production machine 4. These include, for example, a surface of a worktable and a position of a tool tip 14 and/or a spindle of the machine tool and/or production machine 4.

(25) A tool center point of the machine tool and/or production machine 4 is advantageously arranged at the tool tip 14.

(26) The robot 2 can approach these points. For example, by itself having a sensor probe and/or guiding a distance measuring device. For example, a position value of the tool center point 12 in space can be determined by establishing mechanical contact, for example between the tool center point 12 and the worktable.

(27) The position value advantageously comprises three coordinates. A first coordinate advantageously defines a position value of an x-axis, a second coordinate preferably defines a position on the y-axis and a third coordinate preferably indicates a position on a z-axis.

(28) A difference from the position values that the machine tool and/or production machine 4 measures for this point, for example by means of its own sensor probe, is considered to be an error in the robot mechanics at this point, which needs to be compensated.

(29) The machine tool and/or the production machine 4 can be used as a measuring means for this purpose. In this case, errors that the machine tool and/or production machine 4 itself has compared to an ideal or error-free machine tool and/or production machine 4 do not have any effect because the cooperation of the robot 2 and/or the machine tool and/or production machine 4 only requires a relative accuracy of the two devices in relation to one another.

(30) FIG. 2 shows a first possible embodiment.

(31) FIG. 2 shows the system 10 having a robot 2 and a machine tool and/or production machine 4.

(32) FIG. 2 further shows a worktable 20, a zero point of the robot OR and a zero point of the machine tool and/or production machine OW. The tool center point 12 of the robot 2 and the tool tip 14 of the machine tool and/or production machine 4 are also identified.

(33) In this embodiment, the robot 2 is moved until it advantageously makes mechanical contact with the worktable 20. Here, a surface of the worktable 20 can be used when comparing the two coordinate systems. Advantageously, the robot 2 approaches a plurality of positions on the surface of the worktable 20.

(34) It is possible that a coordinate system of the robot 2 is a different coordinate system than that of the machine tool and/or production machine 4. It is then advantageous to convert position values of one coordinate system into the other.

(35) FIG. 3 shows a second possible embodiment.

(36) FIG. 3 shows that the machine tool and/or production machine 4 has a sensor probe 141. The robot 2 approaches the sensor probe 141 such that contact is made between the tool center point 12 and sensor probe 141.

(37) In this case, a deflection of a dial gauge of the sensor probe 141 is a reference for comparing the two coordinate systems

(38) Advantageously, the tool tip 14 of the machine tool and/or production machine 4 is moved to a different position in order to effect a second comparison.

(39) In this case as well, the robot 2 is moved such that the tool center point 12 and the sensor probe 141 are advantageously in contact. The first contact produces a first position value for the robot 2 at a first position and a first position value for the machine tool and/or production machine 4 at the position.

(40) A comparison of the two values can identify a difference. If the two values differ, advantageously the first position value for the robot 2 is corrected such that the two position values are the same. Alternatively, the position value for the machine tool and/or production machine 4 can also be corrected.

(41) The second position value, in particular a second corrected position value, can be ascertained in the same way. Points lying between or outside these position values can be ascertained by means of interpolation or extrapolation.

(42) Advantageously, the robot 2 has a numerical control 98 (see FIG. 6).

(43) Advantageously, the machine tool and/or production machine 4 also has a numerical control 99 (see FIG. 6).

(44) Alternatively, it is conceivable for a higher-level numerical control 100 (see FIG. 7) with two channels 101 and 102 to be available in the system 10 (see FIG. 7).

(45) In this case, a first channel 101 is advantageously assigned to the robot 2. In this case, a second channel 102 is advantageously assigned to the machine tool and/or production machine 4.

(46) FIG. 4 shows the method according to the invention.

(47) In a method step S1, the robot 2 is moved such that a reference point of the robot is located at a first position within the working space of the machine tool and/or production machine 4.

(48) In a method step S2, a first position value for the robot 2 at the first position is compared with a first production value for the machine tool and/or production machine 4 at the position.

(49) If the first position value for the robot 2 differs from the first position value for the machine tool and/or production machine 4 (identified by decision E2, query identified by E), the first position value for the robot 2 is corrected in method step S4.

(50) If the values do not differ (identified by decision E1), no correction is made in method step S3.

(51) Alternatively, the first position value for the machine tool and/or production machine 4 can also be corrected (see method step S4). However, preferably the first position value for the robot 2 is corrected because the accuracy of the machine tool and/or production machine 4 is higher.

(52) The correction is made in such a way that the first position value for the robot 2 and the first position value for the machine tool and/or production machine 4 are the same.

(53) FIG. 5 shows purely by way of example a working space of the robot AR and a working space AW of the machine tool and/or production machine 4. An overlapping region is identified by AW+R.