Method For Operating A Brake And An Associated Machine, In Particular A Robot

Abstract

The invention relates to a method for operating a brake of a machine that has a machine control unit and at least one moveable link that can be actuated by the machine control unit and that can be adjusted by a drive motor actuated by the machine control unit, which motor drives a shaft and which motor, in an engaged (closed) position of a brake that can be automatically actuated by the machine control unit, can be locked by said brake. The invention also relates to a machine with a machine control unit, in particular a robot with a robot control unit, which is configured and/or equipped for carrying out such a method.

Claims

1-13. (canceled)

14. A method for operating a brake of a machine, the machine having a control unit and at least one moveable link that can be actuated by the machine control unit, wherein the link is adjustable by a drive motor that is actuated by the machine control unit, the drive motor driving a shaft and being lockable by the brake in an engaged position of a brake that can be automatically actuated by the machine control unit, the method comprising: providing at least two braking torque values wherein the brake is engaged and that are determined in different rotation angle positions of the shaft distributed over 360 degrees; analyzing the at least two braking torque values by comparing one braking torque value with the at least one other braking torque value; and actuating at least one of the machine, the drive motor, or the brake based on a result from the comparison of the braking torque values.

15. The method of claim 14, wherein: the machine is a robot, the machine control unit is a robot control unit, and the robot has a robot arm actuated by the robot control unit; the robot arm has at least a first link, a second link, and a joint that connects the first link to the second link and that can be adjusted by the drive motor, which drives the shaft and which, in an engaged position of the brake that can be automatically actuated by the robot control unit, can be locked by the brake; and at least one of the robot, the drive motor, or the brake are actuated on the based on the result of the comparison of the braking torque values.

16. The method of claim 14, wherein providing the at least two braking torque values comprises performing a corresponding number of brake tests in different rotation angle positions of the shaft distributed over 360 degrees.

17. The method of claim 16, wherein the machine control unit automatically provides a brake test result qualifying the brake as functional if at least one of the braking torque values provided by the brake tests is greater than a predetermined minimum braking torque value.

18. The method of claim 16, wherein the machine control unit automatically provides a brake test result qualifying the brake as functional only if all of the braking torque values provided by the brake tests are greater than a predetermined minimum braking torque value.

19. The method of claim 16, wherein the machine control unit automatically provides a brake test result qualifying the brake as nonfunctional if at least one of the braking torque values provided by the brake tests is less than a predetermined minimum braking torque value.

20. The method of claim 19 wherein the machine control unit automatically provides a brake test result qualifying the brake as nonfunctional if all of the braking torque values provided by the brake tests is less than a predetermined minimum braking torque value.

21. The method of claim 14, further comprising: determining a first angle range less than 360 degrees which includes at least the rotation angle position of the shaft in which the brake has at least one braking torque value that is less than a predetermined minimum braking torque value; and actuating at least one of the brake or the drive motor in such a way that, with the brake engaged, the shaft comes to a stop in a second angle range that is different from the first angle range.

22. The method of claim 21, wherein at least one of the brake or the drive motor is actuated by the machine control unit.

23. The method of claim 14, further comprising: determining a first angle range less than 360 degrees which includes at least the rotation angle position of the in which the brake has the smallest braking torque value of all braking torque values provided; and actuating at least one of the brake or the drive motor in such a way that, with the brake engaged, the shaft comes to a stop in a second angle range that is different from the first angle range.

24. The method of claim 14, further comprising: determining one or more first angle ranges less than 360 degrees which includes at least the rotation angle position of the shaft in which the brake has braking torque values that are less than a predetermined minimum braking torque value; determining one or more second angle ranges less than 360 degrees which includes at least the rotation angle position of the shaft in which the brake has braking torque values that are equal to or greater than a predetermined minimum braking torque value; and actuating at least one of the brake or the drive motor in such a way that, with the brake engaged, the shaft comes to a stop in the second angle range or in one of the plurality of second angle ranges.

25. The method of claim 14, further comprising displaying the result of the comparison of the braking torques on a display; and actuating the machine based on the result of the comparison of the braking torque values only if an input means to be actuated is activated.

26. A method for determining a minimum braking torque value of a brake of a machine having a machine control unit and at least one moveable link that can be actuated by the machine control unit in accordance with a machine program and that can be adjusted by a drive motor actuated by the machine control unit, which motor drives a shaft and which motor, in an engaged position of a brake that can be automatically actuated by the machine control unit, can be locked by the brake, the method comprising: actuating the machine by the machine control unit or robot control unit (12) according to the machine program or the robot program, determining driving torques of the drive motor in several positions or poses of the at least one link assumed as a result of execution of the machine program; and selecting the largest determined driving torque as a predetermined minimum braking torque value.

27. The method of claim 26, further comprising: storing the selected driving torque in the machine control unit; predetermining a minimum braking torque value; and allowing at least one of an automatic release of the brake or an automatic movement of the at least one link only if the predetermined minimum braking torque value is greater than the stored selected driving torque.

28. The method of claim 27, wherein predetermining a minimum braking torque value comprises receiving a manually input value into the machine control unit.

29. A machine comprising a machine control unit and at least one moveable link that can be actuated by the machine control unit and that can be adjusted by a drive motor actuated by the machine control unit, which motor drives a shaft and which motor, in an engaged position of a brake that can be automatically actuated by the machine control unit, can be locked by the brake; the machine control unit including program code stored in a non-transitory, computer-readable storage medium that, when executed by the machine control unit, causes the machine control unit to: provide at least two braking torque values wherein the brake is engaged and that are determined in different rotation angle positions of the shaft distributed over 360 degrees; analyze the at least two braking torque values by comparing one braking torque value with the at least one other braking torque value; and actuate at least one of the machine, the drive motor, or the brake based on a result from the comparison of the braking torque values.

30. The machine of claim 29, wherein: the machine is a robot, the machine control unit is a robot control unit, and the robot has a robot arm actuated by the robot control unit; and the robot arm has at least a first link, a second link, and a joint that connects the first link to the second link and that can be adjusted by the drive motor, which drives the shaft and which, in an engaged position of the brake that can be automatically actuated by the robot control unit, can be locked by the brake.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Concrete exemplary embodiments of the invention are explained in greater detail in the following description with reference to the attached figures. Concrete features of these exemplary embodiments may show general features of the invention, regardless in what concrete context they are mentioned, perhaps analyzed individually or in combination.

[0053] Wherein:

[0054] FIG. 1 is a perspective illustration of a robot with a robot control unit and a robot arm, the joints of which can be adjusted by electric drive motors,

[0055] FIG. 2 is a schematic illustration of an arrangement of a drive motor and an allocated brake at one of the joints of the robot arm according to FIG. 1,

[0056] FIG. 3 is a sectional view through an exemplary drive motor in which a brake is integrated, which brake sits on the motor shaft,

[0057] FIG. 4 is a graphic four quadrant representation of braking torques of an exemplary brake measured over 360 degrees of rotation angle positions of a motor shaft of an exemplary drive motor,

[0058] FIG. 5 is the graphic four quadrant representation of the braking torques of the exemplary brake measured over 360 degrees of rotation angle positions of the motor shaft of the exemplary drive motor according to FIG. 4, with a second, shaded angle range in which the motor shaft is inventively supposed to come to a stop,

[0059] FIG. 6 is a graphic four quadrant representation of the measured braking torques of another brake, in particular of a different design with several, i.e., three crosshatched second angle ranges in which the motor shaft is inventively supposed to come to a stop, and

[0060] FIG. 7 is an exemplary flowchart of inventive method steps.

DETAILED DESCRIPTION

[0061] FIG. 1 shows a robot 1, comprising a robot arm 2 and a robot control unit 12. The robot arm 2 comprises, in the case of the present exemplary embodiment, several links 14 arranged behind one another and connected via joints 13. The links 14 are in particular a frame 3 and a carousel 4 mounted rotatably about an axis A1 which extends vertically relative to the frame 3. In the case of the present exemplary embodiment, other links of the robot arm 2 are a link arm 5, a cantilever 6, and a preferably multiaxial robot hand 7 with a fastening device configured as a flange 8 for fastening an end effector not shown in greater detail. The link arm 5 is mounted at the bottom end, e.g., on a link arm bearing head not shown in greater detail, on the carousel 4 so that it can pivot about a preferably horizontal axis of rotation A2. At the upper end of the link arm 5, the cantilever 6 is also mounted so that it can pivot about a likewise preferably horizontal axis A3. At its end, this cantilever carries the robot hand 7 with its preferably three axes of rotation A4, A5, A6.

[0062] In the case of the present exemplary embodiment, the cantilever 6 has an arm housing 9 pivotally mounted on the link arm 5. A basic hand housing 10 of the cantilever 6 is mounted on the arm housing 9 so that it can pivot about the axis of rotation A4.

[0063] The robot arm 2 can be moved by means of three electric drive motors 11 in its three basic axes and by means of three additional electric drive motors 11 in its three hand axes.

[0064] The robot control unit 12 of the robot 1 is designed and/or equipped to execute a robot program, by which the joints 14 of the robot arm 2 can be automated according to the robot program or automatically adjusted and/or rotationally moved in a manual drive operation. For this purpose, the robot control unit 12 is connected to the actuatable electric drive motors 11, which are designed to adjust the joints 14 of the robot arm 2.

[0065] By way of an example, one of the drive motors 11 of the robot 1 according to FIG. 1 is shown schematically and by itself in FIG. 2. The illustrated drive motor 11 has a brake 15 that can be automatically actuated by the robot control unit 12 (FIG. 1) and that, in an engaged position, locks the drive motor 11.

[0066] The brake 15 is configured as a safety brake and has a stationary brake part 16, which is connected to the first link 14.1, and a brake part 17 capable of rotating in a released position of the brake 15, which sits (by means of a spline shaft connection, for example) on a shaft 18 driven by the drive motor 11, wherein the shaft 18 is either directly (as shown) coupled or optionally indirectly coupled to the second link 14.2 via an interposed transmission (not shown). In the exemplary embodiment shown, the brake 15 is configured as an electromagnetic brake 15. The brake 15 is configured to be engaged (closed) in a basic state, wherein it brought with spring tensioning by means of spring coils 19 into a released (open) position, in which the brake 15 is held open by means of electrical energy by an electromagnet 20. When the electrical energy is removed, the brake 15 automatically returns to its engaged position (i.e., the basic position) under the spring tensioning, in particular by means of the mechanical spring coils 19.

[0067] An exemplary embodiment of a brake 15 integrated in the drive motor 11 is shown in a sectional view in FIG. 3. Also in this embodiment, the brake 15 is configured as a safety brake and has a stationary brake part 16 and a brake part 17 capable of rotating in a released position of the brake 15, which sits in a rotationally fixed manner on the motor shaft 18a driven by the drive motor 11. The brake 15 is held open by the electromagnets 20.

[0068] FIG. 4 shows the rotation angle-dependent braking torques 21a, 21b as a function of the motor position, i.e., the rotation angle position of the motor shaft 18a of two independent series of measurements at different drive-side positions of the motor shaft 18a over a full 360 degree rotation.

[0069] An inner circle 22 exemplarily represents the design-induced, predetermined minimum target braking torque (minimum braking torque value) specified for this brake 15. An outer circle 23 exemplarily represents the braking torque at which a brake 15 is deemed sufficiently functional. This can be derived from, for example, the predetermined minimum target braking torque, i.e., from the minimum braking torque values (inner circle 22) with an added safety factor.

[0070] It is evident that there are ranges (specifically from 0 degrees to 270 degrees in the exemplary embodiment illustrated) of the motor positions, i.e., of the rotation angle position of the motor shaft 18a, in which the specified (minimum) braking torque cannot be reached, whereas an at least satisfactory braking torque can be reached in other ranges (specifically from 270 degrees to ca. 350 degrees in the exemplary embodiment illustrated) of the motor position.

[0071] FIG. 5 shows the braking torques of the exemplary brake 15 measured over 360 degrees of rotation angle positions of the motor shaft 18a of the exemplary drive motor 11 according to FIG. 4, with a shaded second angle range 24 in which the motor shaft should inventively come to a stop. Hence in the illustrated exemplary embodiment of the motor position, from 270 degrees to ca. 350 degrees an at least satisfactory braking torque can be reached.

[0072] Hence before the deactivated state of the robot is assumed, if necessary and if possible the motor shaft 18a of the exemplary drive motor 11 will assume a rotation angle position within an identified sector (second angle range 24) and only then will the brake 15 be engaged (closed).

[0073] FIG. 6 shows the measured braking torques (represented by the line 21) of another exemplary brake, in particular of another design with several, i.e., three crosshatched second angle ranges 24.1, 24.2, and 24.3 in which the motor shaft should inventively come to a stop.

[0074] According to this exemplary progression of the line 21 of the actual braking torques measured, three angle ranges arise in which the line 21 reaches and/or exceeds the minimum braking torque value defined by the circle 22. Hence in this exemplary embodiment there is a second angle range 24.1 that includes the angle range from ca. 80 degrees to 185 degrees, another second angle range 24.2 that includes the angle range from ca. 225 degrees to 275 degrees, and still another second angle range 24.3 that includes the angle range from ca. 320 degrees to 350 degrees. An at least satisfactory braking torque can be reached in these three angle ranges 24.1, 24.2, and 24.3.

[0075] Hence before the deactivated state of the robot is assumed, if necessary and if possible the motor shaft 18a of the exemplary drive motor 11 will assume a rotation angle position within one of these three identified sectors (crosshatched second angle ranges 24.1, 24.2, and 24.3) and only then will the brake 15 be engaged (closed).

[0076] According to the exemplary flowchart illustrated in FIG. 7, an inventive method has a first step S1 of providing at least two braking torque values, which are determined in different rotation angle positions of the shaft 18, 18a distributed over 360 degrees, with the brake 15 engaged in each case. In a second method step S2, an analysis of the at least two braking torque values is performed by comparing one of the braking torque values with the at least one other braking torque value. In a third step S3, the robot 1, the drive motor 11, and/or the brake 15 are actuated on the basis of a result from the comparison of the braking torque values.

[0077] For providing the at least two braking torque values in step S1, according to a first alternative a corresponding number of brake tests can be performed in different rotation angle positions of the shaft 18, 18a distributed over 360 degrees in an intermediate step S1.1.

[0078] In the analysis according to step S2, in a substep S2.1 the robot control unit 1 can automatically provide a brake test result qualifying the brake 15 as functional if at least one of the braking torque values provided by the brake tests is greater than a predetermined minimum braking torque value.

[0079] In the analysis according to step S2, in a second substep S2.2 as an alternative to the substep S2.1 provision can be made such that the robot control unit 1 automatically provides a brake test result qualifying the brake 15 as functional only if all of the braking torque values provided by the brake tests are greater than a predetermined minimum braking torque value.

[0080] As an alternative or in addition to the substeps S2.1 and S2.2, in a third substep S2.3 the robot control unit 1 can automatically provide a brake test result qualifying the brake 15 as nonfunctional if at least one, in particular all of the braking torque values provided by the brake tests is/are less than a predetermined minimum braking torque value.

[0081] In another substep S2.4, a first angle range less than 360 degrees can be determined that includes at least the rotation angle position in which the brake 15 has the smallest braking torque value of all braking torque values provided.

[0082] In another substep S3.1, the brake 15 and/or the drive motor 11 can be actuated, in particular by means of the robot control unit 12, in such a way that with the brake 15 engaged, the shaft 18, 18a comes to a stop in a second angle range 24 that is different from a first angle range 25.

[0083] In substep S3.1, the first angle range 25, in particular a first angle range 25 of 270 degrees, can comprise the rotation angle position corresponding to the smallest braking torque value, in particular in the middle of the range.

[0084] In substep S3.1, the second angle range 24, in particular a second angle range 24 of 90 degrees, can comprise the rotation angle position corresponding to the greatest braking torque value, in particular in the middle of the range.

[0085] In a supplemental and/or concluding method step S4, the result of the comparison of the braking torques can be displayed to a person operating the robot 1 on a display means 26, in particular at the robot control unit 12. The robot 1, the drive motor 11, and/or the brake 15 are then actuated on the basis of the result from the comparison of the braking torque values only if an input means 27 to be actuated by the person, in particular an input means 27 connected to the robot control unit 12, is activated.

[0086] While the present invention has been illustrated by a description of various embodiments, and while these embodiments have been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. The various features shown and described herein may be used alone or in any combination. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and method, and illustrative example shown and described. Accordingly, departures may be made from such details without departing from the spirit and scope of the general inventive concept.