Apparatus and method for recording positions

Abstract

An apparatus for recording positions in a control program of a manipulator, which includes a manipulator, a controller having a control program, and a manual control device, wherein the controller can actuate the manipulator 10 in a compliance control, in which the manipulator is allowed to occupy an actual position different to the nominal position, wherein the controller, when recording the current position of the manipulator in the control program, carries over into the control program in a situation-based manner the nominal position, the actual position or a hybrid position comprising nominal and actual components of the current position. In addition, a corresponding method is also disclosed.

Claims

1. An apparatus for recording positions in a control program of a manipulator, which includes: the manipulator; a controller having the control program; and an input device; wherein the controller is configured to actuate the manipulator in a compliance control, in which the manipulator is allowed to occupy an actual position different from a nominal position; wherein the controller is configured when recording a current position of the manipulator in the control program to select components of one or more of the nominal position or the actual position of the manipulator to be carried over into the control program, the components selected as a function of a mode by which the manipulator is moved to the current position, and wherein the controller is configured, when the mode by which the manipulator is moved is a hybrid mode in which the manipulator is manually moved into the current position and movement is limited by the controller, to select and carry over into the control program the nominal components of the current position defined by the limitation together with actual components of the current position generated by the manual movement of the manipulator.

2. The apparatus according to claim 1, wherein the controller is configured to define a nominal force (F.sub.nominal) at an end effector of the manipulator and to move the manipulator by means of the controller in such a way that this nominal force (F.sub.nominal) is obtained in the actual position.

3. The apparatus according to claim 1, wherein the manipulator is configured to measure a force (F) of an end effector of the manipulator when it is moved onto a workpiece.

4. The apparatus according to claim 2, wherein the controller is configured to record in the control program the nominal force (F.sub.nominal) for the corresponding actual position.

5. The apparatus according to claim 1, wherein, in the compliance control, a force (F) applied by the manipulator is proportional to a difference between the nominal position and the actual position.

6. The apparatus according to claim 5, wherein the force (F) is determined as a function of the difference between the nominal position and the actual position and a proportionality factor (c) is variably adjustable by the controller wherein the force (F) is determined as a function of the difference between the nominal position and the actual position and a proportionality factor (c) that is variably adjustable by the controller.

7. The apparatus according to claim 1, wherein the controller is configured to record and to store directions in which forces (F, F.sub.nominal) are to act.

8. The apparatus according to claim 1, wherein the controller is configured to record and to store force vectors.

9. A method for recording positions of a manipulator in a control program of a controller of the manipulator, comprising the steps of: controlling a manipulator in a compliance control, in which the manipulator is allowed to occupy an actual position different from a nominal position in current position; selecting components of one or more of the nominal position or the actual position of the manipulator to be carried over in the control program as a function of a mode by which the manipulator is moved to the current position; and recording the selected position in the control program, wherein the mode is a hybrid mode in which the manipulator is manually moved into the current position and movement is limited by the controller, and the controller selects nominal components of the current position defined by the limitation together with actual components of the current position generated by the manual movement of the manipulator.

10. The method according to claim 9, additionally comprising: defining a nominal force (F.sub.nominal) at an end effector of the manipulator; and moving the manipulator in such a way that this nominal force (F.sub.nominal) is obtained in the actual position.

11. The method according to claim 9, additionally comprising: measuring a three (F.sub.nominal) of an end effector of the manipulator when it is moved onto a workpiece.

12. The method according to claim 9, additionally comprising: recording a nominal force (F) at the actual position in the control program by the controller.

13. The method according to claim 9, wherein, in the compliance control, a force (F) applied by the manipulator is proportional to a difference between the nominal position and the actual position.

14. The method according to claim 13, wherein the force (F) is determined as a function of the difference between the nominal position and the actual position and a proportionality factor (c) that is variably adjustable by the controller.

15. The apparatus according to claim 1, wherein the controller is configured, when the mode by which the manipulator is moved is moving the manipulator by means of the input device into the current position, to select and carry over the nominal position of the manipulator into the control program.

16. The apparatus according to claim 1, wherein the controller is configured, when mode by which the manipulator is moved is manually moving the manipulator into the current position, to select and carry over components of the actual position of the manipulator into the control program.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Preferred embodiments of the invention are explained in detail below with reference to the drawings, in which:

(2) FIG. 1 shows a schematic representation of an exemplary apparatus for recording positions in a control program of a manipulator and a workpiece; and

(3) FIG. 2 shows a sequence diagram of an exemplary method for recording positions in a control program of a manipulator.

DESCRIPTION OF PREFERRED EMBODIMENTS

(4) FIG. 1 shows an apparatus 1 for recording positions 12, 14 in a control program 22 of a manipulator 10 upon contact with a workpiece 40. The apparatus 1 comprises a manipulator 10, which is actuated by a controller 20, which can be activated or programmed by a user (not shown) by means of an input device 30, for example a manual control device.

(5) The manipulator 10 additionally comprises several moveable and motor-actuatable axes and an end effector 16. The end effector 16 can be, for example, a gripper, a suction device or another tool, with which the manipulator 10 moves or machines objects, for example. In particular, the end effector 16 can be a tool, for example, a grinding machine, with which the workpiece 40 can be machined.

(6) The input device 30 can include a space mouse 34 and/or keys 32, by means of which the manipulator 10 can be moved to a desired position and programmed by the user.

(7) The manipulator 10 can be a so-called lightweight robot (LWR), which is particularly suitable for assembly operations and lighter machining operations. Internal force sensors in the lightweight robot allow a safe human-robot cooperation thanks to monitoring of the forces occurring.

(8) In particular, the controller 20 can actuate the manipulator 10 in the compliance control, in particular in a Cartesian compliance control, with the manipulator in being allowed to occupy an actual position 14 in the static state, which differs significantly from the nominal position 12. FIG. 1 shows, by way of an example, that the TCP of the end effector 16 is situated at the upper surface 42 of the workpiece 40 at the actual position 14, while the nominal position 12, moved downwards by the amount of the distance ΔX, is situated inside the workpiece 40. For the sake of clarity, the end effector 16 situated in the nominal position 12 is indicated with a broken line. If the workpiece 40 was not present, the manipulator 10 would occupy the nominal position 14.

(9) In the situation depicted in FIG. 1, the manipulator 10 applies a force F to the upper surface 42 of the workpiece 40 with the end effector 16. The manipulator 10 outwardly behaves as if it contains a spring, which draws the manipulator 10 from the actual position 14 to the nominal position 12. The force F is calculated in accordance with the spring principle:
F=c*(X.sub.Soll−X.sub.ISt)=c*ΔX
[Translation of formula text: Soil=nominal, Ist=actual]

(10) In the stiffness control, the spring constant c can be additionally adjusted by the controller 20. The manipulator 10 is thus able to apply in the stiffness or compliance control precisely defined contact or process forces F to its end effector 16, for example, a tool, and accordingly, to the workpiece 40.

(11) In the teaching or touch-up, current positions of the manipulator 10 are carried over into a control program 22 of the manipulator 10. The manipulator 10 can either be moved in a conventional manner by means of the input device 30 into the desired position or can be manually moved by the user into the desired position.

(12) The information about the movement type is registered by the controller 20.

(13) If the manipulator 10 is moved to a desired position with the input device 30 by means of a space mouse 34 or by means of keys 32, and a teaching or touch-up is to then occur, the controller 20 carries over the current nominal position 12 into the control program 22. It is thus also possible to set the force F, by means of a keypress or a mouse movement, with which the manipulator 10 is to act on the surrounding environment, in this case, the workpiece 40.

(14) In the example depicted in FIG. 1, the manipulator 10 is initially moved to the position 14, at which the end effector 16 is just touching the upper surface 42 of the workpiece 40. In this position, the manipulator 10 is not yet applying any force F to the workpiece 40. The user can now, for example, by means of the space mouse 34 or an axis movement key, in this case preferably the Z movement key on the input device 30, virtually move the manipulator 10 in the Z direction to the nominal position 12, wherein the end effector 16 does not, however, penetrate the workpiece 40, but instead remains in the actual position 14. Thanks to the virtual movement the manipulator is now “pre-loaded” and applies a precisely defined force F, which can be calculated in accordance with the spring principle, to the workpiece 40. With the teaching or touch-up of the nominal position 12, at a defined spring constant c, the force F is thus implicitly also recorded in the control program 22.

(15) As an alternative to the virtual movement of the manipulator 10 to apply a force F, the manipulator can also be moved to the actual position 14 or manually moved thereto, and then a nominal force F.sub.nominal desired there can be defined via the input device 30. The manipulator 10 is then virtually moved onto the workpiece or pre-loaded according to this nominal force F.sub.nominal, so that the desired nominal force F.sub.nominal is obtained. The movement path is, in turn, defined according to the spring principle. In this case too, in the teaching or touch-up, the nominal position 12 resulting from the nominal force F.sub.nominal is recorded in the control program 22 and thus, at a defined spring constant c, the force F is implicitly also stored. The user can preferably also define a direction or direction curve for the force F or nominal force F.sub.nominal, in which said force is to act.

(16) Alternatively, in the case of the force definition, the actual position 14 and the desired force F.sub.nominal can also be stored and the controller 20 can then calculate from this information, in the subsequent independent execution of the control program 22, the required nominal position 12 based on the spring principle.

(17) If the manipulator 10 is manually moved by a user to a desired position, and a teaching or touch-up is to then occur, the controller 20 carries over the current actual position 12 into the control program 22. The controller assumes that the user normally does not want to apply any force to the surrounding environment with the manipulator 10. However, if the manipulator 10 is configured to measure a force F of the end effector 16 when it is moved onto a workpiece 40, in the teaching or touch-up for the current actual position 14, the measured force F can also be recorded as nominal force F.sub.nominal in the control program 22.

(18) It is additionally possible that, in the teaching or touch-up, the manual movement option of the TCP was limited for the end effector 16 by a subspace of the movement. For example, the TCP could be moved in the Z direction by means of the input device 30 in such a way that it applies a defined force F to the workpiece 40. This Z component should subsequently be maintained exactly the same, even in the case of a manual movement. The orientation of the TCP or tool could also be precisely defined. Then the movement of the manipulator in the X-Y plane of the upper surface 42 could be enabled and the manipulator could be manually moved by the user in this X-Y plane. In a subsequent teaching or touch-up, a hybrid position is now recorded in the control program 22, which position is made up of the precisely defined Z component, the precisely defined solid angles A, B and C, i.e. the nominal components, and the measured values for the X and Y components, i.e. the actual components.

(19) FIG. 2 illustrates an exemplary method for recording positions 12, 14 in a control program 22 of a manipulator 10 by means of a sequence diagram.

(20) In a step 50, the manipulator 10 is controlled in the compliance control, in which the manipulator 10 is allowed to occupy an actual position 14 different to a nominal position 12. The manipulator 10 can either be moved by means of an input device 30 into the current position in sub-step 52, or can be moved manually by the user into the current position in sub-step 54.

(21) In the teaching or touch-up, the current position is recorded in the control program 22 in a step 60, while in sub-step 62 the nominal position 12 is recorded if the manipulator 10 was moved by means of the input device 30 into the current position. In an alternative sub-step 62, the current actual position 14 is recorded in the control program 22 if the manipulator 10 was manually moved by a user into the current position. As another alternative, in a sub-step 66, a hybrid position composed of nominal and actual components can be recorded in the control program 22 if the manipulator 10 was manually moved by a user into the current position and the movement was limited by the controller 20.

(22) It should be noted that the invention claimed herein is not limited to the described embodiments, but may be otherwise variously embodied within the scope of the claims listed infra.

REFERENCE NUMERAL LIST

(23) 1 Apparatus 10 Manipulator 12 Nominal position 14 Actual position 16 End effector 20 Controller 22 Control program 30 Input device 32 Keys 34 Space mouse 40 Workpiece 42 Upper surface 50 Control step in compliance control 52 Movement by means of manual control device 54 Manual movement 60 Recording of the position 62 Recording of the nominal position 64 Recording of the actual position 66 Recording of a hybrid position