MONITORING METHOD AND MONITORING SYSTEM

Abstract

A monitoring method for a robot. The actual internal loads are measured with a sensor at a reference point of the robot and are compared with the expected internal loads. The expected internal loads are calculated using the movement of the robot and a dynamic model. It is possible to estimate which external forces act on the robot by comparing the actual and expected internal loads. The signal characteristics of different signal components in the signal of the estimated external forces are used to differentiate between said signal components.

Claims

1-19. (canceled)

20. A method of monitoring a robot, comprising: detecting actual internal loads at a reference point of the robot with a sensor at the reference point; obtaining a measured or estimated robot state, wherein the robot state comprises at least one of a position, speed, or acceleration of moving parts of the robot; calculating expected internal loads at the reference point from a mathematical dynamic model of the robot and the obtained robot state; estimating external forces on the robot based on a comparison of the expected internal loads and the actual internal loads; distinguishing different signal components of the estimated external forces on the basis of a signal characteristic; wherein distinguishing the different signal components comprises detecting certain external stresses on the basis of defined decision rules; and qualifying the distinction result with respect to the probable loading cause of the signal components.

21. The method of claim 20, wherein at least one of: the reference point is a point between a foot and a frame of the robot; the reference point is at a joint of the robot; the sensor is a force-torque sensor; or different signal components are distinguished on the basis of a frequency characteristic of the signal.

22. The method of claim 20, wherein detecting certain external stresses comprises detecting conscious human interactions or unexpected collisions of the robot with objects or humans.

23. The method of claim 20, further comprising: generating a control signal for the robot or triggering a certain operating mode of the robot in in response to detecting a certain external load in the distinction result.

24. The method of claim 20, further comprising: filtering the signal of the estimated external forces with one or more signal filters in order to distinguish the various signal components.

25. The method of claim 20, further comprising evaluating the distinction result by a threshold value comparison.

26. The method of claim 20, wherein obtaining the measured or estimated robot state comprises obtaining the robot state for a tool or another attachment of the robot.

27. A monitoring system for a robot, comprising a computer including computer code stored in a non-transient computer-readable storage medium, the computer code configured, when executed by the computer, to cause the computer to: detect actual internal loads at a reference point of a robot with a sensor at the reference point; obtain a measured or estimated robot state, wherein the robot state comprises at least one of a position, speed, or acceleration of moving parts of the robot; calculate expected internal loads at the reference point from a mathematical dynamic model of the robot and the obtained robot state; estimate external forces on the robot based on a comparison of the expected internal loads and the actual internal loads; and distinguish different signal components of the estimated external forces on the basis of a signal characteristic.

28. The monitoring system of claim 27, wherein the monitoring system is configured for human-robot collaboration and adapted to detect unexpected collisions of the robot to be monitored and to distinguish the unexpected collisions from conscious interaction of a human with the robot.

29. The monitoring system of claim 27, wherein the monitoring system is configured as a separate control unit or implemented in a robot controller of the robot.

30. The monitoring system of claim 27, further comprising a sensor interface for exchanging signals with a sensor.

31. The monitoring system of claim 30, wherein the sensor is a force-torque sensor.

32. The monitoring system of claim 27, further comprising a robot interface configured to exchange signals with the robot or its robot controller.

33. The monitoring system of claim 27, further comprising a dynamic unit adapted to obtain the robot state and to calculate the expected internal loads at the reference point using a mathematical dynamic model of the robot.

34. The monitoring system of claim 27, further comprising a distinction unit adapted to distinguish or separate signal components in the signal of the estimated external forces on the basis of the signal characteristic.

35. The monitoring system of claim 34, wherein the distinction unit comprises signal filters.

36. The monitoring system of claim 27, further comprising an evaluation unit adapted to detect certain external loads on the robot based on the distinction result.

37. The monitoring system of claim 27, wherein the monitoring system is configured to at least one of: generate a control signal in response to a certain external load; or trigger a certain operating mode of the robot [in response to the distinction].

38. An industrial robot, comprising: a movable robot arm supported on a robot foot for movement about at least one linear or rotating movement axis, and a robot controller controlling movement of the robot arm; the robot foot configured to be fastened on a frame; a sensor configured to calculate at least one of the internal forces or torques at a reference point between the frame and a part of the robot arm; and a monitoring system configured to: detect actual internal loads at a reference point of a robot with a sensor at the reference point, obtain a measured or estimated robot state, wherein the robot state comprises at least one of a position, speed, or acceleration of moving parts of the robot, calculate expected internal loads at the reference point from a mathematical dynamic model of the robot and the obtained robot state, estimate external forces on the robot based on a comparison of the expected internal loads and the actual internal loads, and distinguish different signal components of the estimated external forces on the basis of a signal characteristic.

39. The robot of claim 38, wherein the robot is configured to operate in at least one of an automatic mode, an interaction mode, or a collision mode.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the principles of the invention.

[0029] FIG. 1 is a schematic representation of the monitoring method with a monitoring system.

DETAILED DESCRIPTION

[0030] FIG. 1 shows a schematic representation of a monitoring system (30) for monitoring a robot (1) with a force-torque sensor (20) between the robot foot (12) and a frame (5) of the robot. A schematic signal flow of a possible embodiment is shown. The monitoring system (30) receives a signal of the measured, actual internal loads (40) at the reference point (13) via a sensor interface (31). The actual internal loads are compared with the expected internal loads (41). The external forces are estimated and a signal of the estimated external forces (42) is generated. The expected internal forces (41) are calculated by a dynamic unit (33) with a mathematical dynamic model of the robot.

[0031] In this preferred embodiment, the distinctive unit (34) comprises two linear signal filters. A high-pass filter (35) suppresses low-frequency signal components. A notch filter (36) suppresses known, especially learned, interference frequencies. The distinction result (43) does not include any low-frequency signal components due to human interactions as a result of filtering.

[0032] By means of a threshold value comparison, an evaluation unit (37) recognizes in the distinction result (43), in this case the filtered signals of the estimated external forces, whether there is an unexpected collision of the robot (1). If a specific threshold value in the level of the distinction result is exceeded, a control signal (47) can be generated. The control signal can be transmitted via a robot interface (32), in particular to a robot controller (17).

[0033] A robot (1) can have any number and combination of rotatory- and/or translationally-driven robot axes. The robot (1) comprises a movable robot arm (11), a robot foot (12), at least one linear or rotating motion axis (15) and a robot controller (17). An industrial robot (1) can stand on a frame (5) or directly on a foundation with a robot foot (12). Alternatively, the robot (1) can also be suspended from a frame (5). The robot (1) is supported against its surroundings by a robot foot (12) on a frame (5). The robot foot (12) has suitable fastening means to be fastened directly to a frame (5) or to a sensor (20). The sensor (20) can also be retrofitted as a force-torque sensor on robots which were previously mounted directly on a frame (5). The sensor (20) is arranged with suitable interfaces between robot foot (12) and a frame (5) or foundation.

[0034] The reference point (13) for measuring the internal loads with a local sensor (20) can be located at different points on the robot. Preferably, the reference point is between the robot foot (12) and a frame (5). In this preferred embodiment, all loads on the robot can be detected in the internal loads. Alternatively, the reference point can also be located between two moving parts of the robot arm (11) or between the robot arm (11) and the robot foot (12).

[0035] The robot (1) comprises a monitoring system (30). The monitoring system may be part of the robot controller (17).

[0036] According to a first embodiment, the monitoring method is carried out by a monitoring system (30), which communicates with a robot controller via a robot interface (32).

[0037] According to an alternative version, the monitoring system can be implemented in the controller of the robot controller and exchange signals with other parts of the robot controller via internal interfaces.

[0038] A particularly interesting application of the invention lies in the production of different variants, whereby one variant is produced much less frequently than the other. Here it can be economically advantageous to operate the robot only for the frequent variants in a preprogrammed manufacturing process in automatic mode. For the production of the rare variants, the robot can be guided by an operator. The robot switches to an interaction mode. This reduces the effort for programming the robot. The profitability of the robot system is thus improved.

[0039] Modifications of the invention are possible in different ways. In particular, the features shown, described or claimed for the respective embodiments can be combined with each other in any way, replaced against each other, supplemented or omitted.

[0040] 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.

LIST OF REFERENCE SIGNS

[0041] 1 Robot [0042] 5 Frame [0043] 11 Robot arm [0044] 12 Robot foot [0045] 13 Reference point [0046] 14 Joint [0047] 15 Motion axis [0048] 17 Robot controller [0049] 18 Robot state (signal) [0050] 20 Sensor; force-torque sensor [0051] 30 Monitoring system [0052] 31 Sensor interface [0053] 32 Robot interface [0054] 33 Dynamic unit [0055] 34 Distinction unit [0056] 35 Signal filter; high-pass filter [0057] 36 Signal filter; notch filter [0058] 37 Evaluation unit [0059] 40 Actual internal loads (signal) [0060] 41 Expected internal loads (signal) [0061] 42 Estimated external forces (signal) [0062] 43 Distinction result [0063] 47 Control signal