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 and the brake activation device is formed, bringing the locking element into engagement with a brake element when required in order to stop rotation of the rotor, wherein a detected position of at least one brake element is compared with a stored absolute position with respect to this brake element.

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 therebetween in the circumferential direction, and wherein the brake activation device is adapted to bring the locking element into engagement with a brake element when required to stop rotation of the rotor, the method comprising the steps of: actuating the locking element; 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; and comparing the detected position with a stored absolute position of the first brake element.

2. The method according to claim 1, comprising the further steps: releasing the locking element; rotating the rotor 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 comparing of the detected position with stored absolute positions of the second brake element.

3. The method according to claim 1, in which the torque is varied when the locking element is applied to the brake element(s).

4. The method according to claim 1, in which the rotor comprises a plurality of equidistantly arranged brake elements, comprising the step of: repeating the steps according to the number of brake elements present.

5. The method according to claim 4, in which these steps are carried out in one direction of rotation; or one after the other in both directions of rotation.

6. The method according to claim 1, in which the method is carried out individually for each joint of a multi-axis articulated arm robot.

7. The method according to claim 1, in which the braking device is blocked and/or the articulated arm robot is stopped if the detected position(s) deviates from the stored position(s) by a defined threshold value (.sub.max).

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

9. A data carrier device on which a computer program according to claim 8 is stored.

10. A computer system comprising a data processing apparatus, the data processing apparatus being arranged such that a method according to claim 1 is carried out on the data processing apparatus.

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

12. The method according to claim 2, in which the torque is varied when the locking element is applied to the brake element(s).

13. The method according to claim 2, in which the rotor comprises a plurality of equidistantly arranged brake elements, comprising the step of: repeating the steps according to the number of brake elements present.

14. The method according to claim 3, in which the rotor comprises a plurality of equidistantly arranged brake elements, comprising the step of: repeating the steps according to the number of brake elements present.

15. The method according to claim 13, in which these steps are carried out in one direction of rotation; or one after the other in both directions of rotation.

16. The method according to claim 14, in which these steps are carried out in one direction of rotation; or one after the other in both directions of rotation.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0050] Further advantages and features of the present invention result from the description of the embodiment shown in the enclosed drawings.

[0051] FIG. 1 is an example of a perspective view of a braking device according to the invention;

[0052] FIG. 2 is a schematic representation of the segments of a brake star and the positions of the individual elements in relation thereto;

[0053] FIG. 3 is a schematic representation of the segments at an angular offset of the brake star; and

[0054] FIG. 4 exemplary illustrates a flow chart of the method according to the invention.

DETAILED DESCRIPTION

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] The brake star 5 has 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.

[0060] By means of the preferably solenoid-operated brake activation device 1, bolt 2 can be moved between a locked position, which it occupies without energy supply, and a release position occupied when energy is supplied. FIG. 1 shows bolt 2 in such a release position; this bolt 2 is located axially below the rotating brake star 5, thus 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.

[0061] FIG. 2 schematically shows the segmentation of the brake star 5 with the relative positions of the individual webs 7 and bolt 2.

[0062] 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 due to their design, 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.

[0063] 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 of the motor position have been determined in advance and stored, and since the absolute, since stationary position PB of bolt 2 is known, it is then possible in the following to determine where the individual positions of the edges 9 are located by detecting the angular position of the rotor 4 or of the motor shaft in the control system, and thus to determine that circumferential segment UB in which bolt 2 is actually located after braking or locking has been carried out.

[0064] FIG. 3 shows schematically how the positions of the edges 9 have changed if the brake star 5 slips unintentionally in relation to the axis of the rotor 4. By moving the brake star 5, i.e. each brake element 7 towards the brake bolt 2, it is possible to detect, via corresponding algorithms implemented in the control system, that the edges 9 of the individual webs 7 have shifted by an angle in one direction of rotation. This angle is compared with a stored threshold value .sub.max for this angle and, if it is exceeded, the controller causes the joint relating to this braking device and therefore the entire robot to stop.

[0065] FIG. 4 schematically shows a flowchart with respect to the method according to the invention.

[0066] In a first step S1, locking bolt 2 is actuated so that in a subsequent step S2, when the brake star 2 is rotated, a first web 7 comes to rest against locking bolt 2 under a defined torque. Since the original position of the edge 9 of this web 7 coming into contact is known, it can be calculated in a further step S3 by means of the degree of rotation whether this original position of the edge 9 is maintained, taking into account certain tolerance ranges which influence the threshold value .sub.max, or whether a deviation can be detected, i.e. a new position of the edge 9 could be recorded.

[0067] In a comparison step S4 this deviation is compared with the threshold value .sub.max. If it still moves in an area that indicates sufficient functionality of the braking device, the robot system is released for further operation in a step S5. However, if this threshold value .sub.max is exceeded, according to the invention the robot is stopped in an alternative step S6.

[0068] Ideally, 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, and then again preferably at fixed intervals over the period of use of the robot.