METHOD OF CONTROL OF BRAKE DEVICES IN A ROBOT SYSTEM AND ROBOT

Abstract

A method for controlling a braking device for a drive unit of a joint between two members of a multi-axis robot arm of an articulated arm robot including a brake activation device and a locking element, wherein the drive unit includes a rotor with at least two radial brake elements, wherein the brake elements are rotated such that the locking element is always exposed. Further described is a method for determining the positions of the radial brake elements.

Claims

1. A method for controlling a braking device for a drive unit of a joint between two members of a multi-axis robot arm of an articulated arm robot comprising a brake activation device and a locking element, wherein the drive unit comprises a rotor with at least two radial brake elements, each enclosing a free circumferential segment (U) therebetween in the circumferential direction, and wherein the brake activation device is adapted to bring the locking element into engagement with at least one brake element when required to stop rotation of the rotor, the method comprising the steps of a) detecting the current positions of said at least two brake elements; b) determining of that circumferential segment (UB) in which the locking element is located; and c) detecting within the determined circumferential segment (UB) the respective distances (S1, S2) of the at least two brake elements from the locking element.

2. The method according to claim 1, further comprising the step: d) depending on the detected distances (S1, S2), rotating the brake elements relative to the locking element by at least such an angle that the locking element is exposed in the determined circumferential segment (UB).

3. The method according to claim 2, in which the angle is selected such that the locking element is arranged at equal distances from the brake elements enclosing it.

4. The method according to claim 2, further comprising the step e) releasing the locking element in this position.

5. The method according to claim 4, in which the steps a) to e) of the method are carried out for a first joint of the multi-axis robot arm, and upon successful release, the steps a) to e) of the method are carried out for a second joint following the first joint.

6. The method according to claim 5, in which the steps a) to e) of the method are carried out consecutively in one of the two sequences of the joints of the multi-axis robot arm separately for each joint.

7. The method according to claim 1, in which the step a) of detecting the current positions of the at least two brake elements comprises: determining the positions from stored absolute positions of the at least two brake elements in relation to an absolute position of the rotor and/or the locking element.

8. The method according to claim 7, before carrying out one of steps a) to c), further comprising the step: detecting the absolute positions of the at least two brake elements in relation to the rotor.

9. The method according to claim 8, in which the step of detecting absolute positions comprises the steps actuating the locking member; and rotating the brake elements until a first brake element comes to rest against the locking element under a defined torque; detecting the position of the blocked first brake element; releasing the locking element; rotating the brake elements until a second brake element comes to rest against the locking element under a defined torque; and detecting of the position of the blocked second brake element.

10. The method according to claim 8, in which the rotor has a plurality of brake elements arranged equidistantly in the circumferential direction, comprising repeating the steps according to the number of brake elements present.

11. The method according to claim 10, in which the steps are carried out in one rotational direction; or successively in both rotational directions.

12. A method for controlling a braking device for a drive unit of a joint between two members of a multi-axis robot arm of an articulated arm robot comprising a brake activation device and a locking element, wherein the drive unit comprises a rotor with at least two radial brake elements, each enclosing a free circumferential segment (U) therebetween in the circumferential direction, and wherein the brake activation device is adapted to bring the locking member into engagement with a brake member when required to stop rotation of the rotor, the method comprising the steps of actuating the locking member; rotating the brake elements until a first brake element comes to rest against the locking element under a defined torque; detecting the position of the blocked first brake element; releasing the locking element; rotating the brake elements until a second brake element comes to rest against the locking element under a defined torque; detecting the position of the blocked second brake element; and defining the detected positions as absolute positions of the brake elements in relation to an absolute position of the rotor.

13. The method according to claim 12, in which the torque is varied when the locking element rests against the brake element.

14. The method according to claim 12, in which the absolute positions are stored in a memory associated with the joint in the drive unit.

15. The method according to claim 12, in which the rotor comprises a plurality of equidistantly arranged brake elements, comprising the step repeating the steps according to the number of brake elements present.

16. The method according to claim 15, in which these steps are carried out in one direction of rotation; or one after the other in both directions of rotation.

17. The method according to claim 12, in which the method is carried out individually for each joint of a multi-axis articulated arm robot.

18. A computer program comprising program instructions which cause a processor to execute and/or control the steps of the method according to claim 1 when the computer program is running on the processor.

19. A data carrier device on which a computer program according to claim 18 is stored.

20. A computer system comprising a data processing apparatus, the data processing apparatus being arranged such that the method according to claim 12 is performed on the data processing apparatus.

21. A robot system with a multi-axis robot arm comprising means for carrying out the process according to claim 1.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0053] Further advantages and features of the present invention result from the description of the embodiment shown in the enclosed drawings.

[0054] FIG. 1 is an example of a perspective view of a braking device according to the invention; and

[0055] FIG. 2 is a schematic representation of the segments of a brake star and the positions of the individual elements in relation to these segments.

DETAILED DESCRIPTION

[0056] The braking device shown schematically in FIG. 1 according to the invention can preferably be attached to the front face of one end of a drive unit of a joint between two members of a robot arm, preferably in a joint unit as described in German patent application No. 10 2016 004 787.9.

[0057] The braking device according to the invention comprises a brake activation device 1, which may be a magnet-activated holding or spring mechanism, for example. The brake activation device 1 is conceived and designed to activate a locking element in the form of a bolt 2 when required, e.g. in the event of an unexpected power failure, whereby the bolt 2 is then driven upwards, e.g. by a spring.

[0058] By means of a bearing disk 3, which is fixed to the housing, i.e. connected to a (not shown) housing of the drive unit, a motor shaft or a rotor 4 of the drive unit can be supported by known bearings (not shown). The brake activation device 1 with the bolt 2 is arranged stationary on the bearing disk 3.

[0059] The rotor 4 carries a brake element in the form of a brake star 5, which is connected, e.g. glued, to the rotor 4 in a rotationally fixed manner via an axially extending sleeve 6.

[0060] The brake star 5 comprises three webs 7 spaced at an equal circumferential angle to each other, which extend radially from an inner ring 8 of the brake star 5.

[0061] By means of the preferably solenoid-operated brake activation device 1, bolt 2 can be moved between a locked position, in which it remains without energy supply, and a release position to be taken up when energy is supplied. FIG. 1 shows bolt 2 in such a release position; this bolt 2 is located underneath the rotating brake star 5, seen in the axial direction, and is therefore out of engagement with one of the webs 7. When the energy is switched off, the bolt is forced towards the brake star 5 by the spring force of a spring, which is then released by a magnet which is no longer activated, and thus passes between two adjacent webs 7 of the rotating brake star 5, whereby an abrupt braking of the drive shaft or the rotor 4 is realized as soon as the next web 7 hits against the bolt 2.

[0062] FIG. 2 schematically shows the segmentation of the brake star 5 with the relative positions of the individual webs 7 and the bolt 2.

[0063] The webs 7 are arranged at an equal distance from each other, i.e. with three webs 7, their central radial axes S are 120 apart. Since the webs 7 themselves have a certain width, as shown in FIG. 1, e.g. a circumferential extension US of 40, the edges 9 of the webs 7, against which the bolt 2 comes to rest, include free circumferential segments U with an angular extension of 80.

[0064] Since the positions of the edges 9 on both sides of each web 7 in relation to the angular position of the rotor 4 and thus the motor position have been determined and stored in advance, if necessary by a separate measuring method, and since the absolute, since stationary position PB of bolt 2 is known, it can then be determined by means of the detection of the angular position of the rotor 4 or of the motor shaft in the control system, where the individual positions of the edges 9 are located, and thus that circumferential segment UB can be determined in which bolt 2 is actually located after braking or locking has been carried out.

[0065] From this, the circumferential distances S1 and S2 of bolt 2 to the edges 9 enclosing the circumferential segment UB can be calculated.

[0066] The control system according to the invention is designed in such a way that, depending on the detected and calculated positions, the brake star 5 is then rotated in such a direction that the bolt 2 is certainly located freely in the circumferential segment UB, i.e. without risk of contact and thus blockage with one of the edges 9 of the adjacent webs 7, preferably in such a way that the distance S1 is equal to the distance S2, i.e. the bolt 2 lies on a central line M of the circumferential segment UB.

[0067] In this position, bolt 2 can then be transferred to its release position, i.e. the braking device can be released. According to the invention, this is preferably then carried out by an active control of the brake activation device 1, which retracts bolt 2 into its release position.

[0068] The steps described above are carried out individually, preferably consecutively from one end to the other end, for each joint of the multi-axis robot arm when a robot is activated.