Method and system for operating a multi-axis machine, in particular a robot

Abstract

A method for operating a multiple axis machine includes controlling drives of the machine with a machine control system and monitoring the machine with a fail-safe control system having first and second redundant channels. Each of the first and second channels receives first input target values and first input actual values from the machine control system, and compares first reference target values (based on the first input target values) with first reference actual values (based on the first input actual values). A fault reaction is triggered if there is a deviation between the compared values that exceeds a specified tolerance. The first input values comprise reference position values of a machine-fixed reference or time derivatives thereof, and the machine control system determines target and/or actual reference position values based on a transformation between reference position values of the machine-fixed reference and axial position values of the machine.

Claims

1. A method for operating a multiple axis machine, wherein the machine includes a machine control system that controls drives of the machine, and a fail-safe control system that includes a first channel and a redundant, second channel which monitor the machine, the method comprising: in the first channel: receiving first input target values and first input actual values from the machine control system, comparing first reference target values, which depend on the first input target values, with first reference actual values, which depend on the first input actual values, with each other, and triggering a fault reaction when a deviation between the first reference target values and the first reference actual values exceeds a specified tolerance; and in the second channel: receiving first input target values and first input actual values from the machine control system, comparing first reference target values, which depend on the first input target values, with first reference actual values, which depend on the first input actual values, and triggering a fault reaction when a deviation between the first reference target values and the first reference actual values exceeds a specified tolerance; wherein the first input target values and the first input actual values comprise at least one of reference position values of a machine-fixed reference of the machine, or time derivatives of the reference position values; and wherein the machine control system determines at least one of these target reference position values or actual reference position values based on a transformation between reference position values of the machine-fixed reference and axial position values of the machine.

2. The method of claim 1, wherein the multiple axis machine is a robotic manipulator.

3. The method of claim 1, wherein the second channel of the fail-safe control system is dissimilar from the first channel.

4. The method of claim 1, further comprising: in the first channel: receiving second input target values and second input actual values, comparing second target values, which depend on the second input target values, with second reference actual values, which depend on the second input actual values, and triggering a fault reaction when a deviation between the second reference target values and the second reference actual values exceeds a specified tolerance; and in the second channel: receiving second input target values and second input actual values, comparing second reference target values, which depend on the second input target values, with second reference actual values, which depend on the second input actual values, and triggering a fault reaction when a deviation between the second reference target values and second reference actual values exceeds a specified tolerance; wherein the second input target values and the second input actual values comprise at least one of the axial position values of the machine or time derivatives of the axial position values.

5. The method of claim 4, wherein the machine control system determines the target axial position values which the first and second channels receive from the machine control system, on the basis of a transformation between the reference position values of the machine-fixed reference and the axial position values of the machine.

6. The method of claim 1, wherein at least one of the input target values, the reference target values, or the reference actual values are determined on the basis of lag errors, wherein the lag errors are determined in the drive control units and/or by time differentiation.

7. The method of claim 1, wherein the first and second channels receive from the machine control system at least one of: the same first input target values; the same second input target values; or the same first input actual values.

8. The method of claim 1, wherein the first and second channels receive redundantly determined second input actual values from an acquisition means.

9. The method of claim 1, wherein the first and second channels compare the respective reference target values and/or reference actual values with preset threshold values and trigger a fault reaction in the event that a deviation exceeds a specified tolerance.

10. The method of claim 9, wherein the preset threshold values are variable.

11. The method of claim 1, further comprising: carrying out a self-test with the fail-safe control system; and triggering a fault reaction in the event that the self-test indicates a malfunction.

12. The method of claim 11, wherein the self-test is carried out cyclically.

13. The method of claim 1, further comprising triggering a fault reaction in the event that the fail-safe control system receives an external error signal.

14. A system for operating a multiple axis machine, said system comprising: a machine control system for controlling the drives of the machine; a fail-safe control system configured for monitoring the machine and that comprises a first channel and a redundant, second channel; a storage medium including program code that, when executed by the fail-safe control system, causes the fail-safe control system to: in the first channel: receive first input target values and first input actual values from the machine control system, compare first reference target values, which depend on the first input target values, with first reference actual values, which depend on the first input actual values, with each other, and trigger a fault reaction when a deviation between the first reference target values and the first reference actual values exceeds a specified tolerance; and in the second channel: receive first input target values and first input actual values from the machine control system, compare first reference target values, which depend on the first input target values, with first reference actual values, which depend on the first input actual values, and trigger a fault reaction when a deviation between the first reference target values and the first reference actual values exceeds a specified tolerance; wherein the first input target values and the first input actual values comprise at least one of reference position values of a machine-fixed reference of the machine or, time derivatives of the reference position values; and wherein the machine control system determines at least one of target reference position values or actual reference position values based on a transformation between the reference position values of the machine-fixed reference and axial position values of the machine.

15. The system of claim 14, wherein the multiple axis machine is a robotic manipulator.

16. The system of claim 14, wherein the second channel of the fail-safe control system is dissimilar from the first channel.

17. An arrangement comprising a robotic manipulator and the system of claim 14.

18. A computer program product for use with a multiple axis machine, wherein the machine includes a machine control system that controls drives of the machine, and a fail-safe control system that includes a first channel and a redundant, second channel which monitor the machine, the computer program product having programming code stored on a non-transitory machine readable data medium, the programming code configured to, when executed by the fail-safe control system, cause the fail-safe control system to: in the first channel: receive first input target values and first input actual values from the machine control system, compare first reference target values, which depend on the first input target values, with first reference actual values, which depend on the first input actual values, with each other, and trigger a fault reaction when a deviation between the first reference target values and the first reference actual values exceeds a specified tolerance; and in the second channel: receive first input target values and first input actual values from the machine control system, compare first reference target values, which depend on the first input target values, with first reference actual values, which depend on the first input actual values, and trigger a fault reaction when a deviation between the first reference target values and the first reference actual values exceeds a specified tolerance; wherein the first input target values and the first input actual values comprise at least one of reference position values of a machine-fixed reference of the machine, or time derivatives of the reference position values; and wherein the machine control system determines at least one of target reference position values or actual reference position values on the basis of a transformation between the reference position values of the machine-fixed reference and axial position values of the machine.

Description

(1) Other advantages and features will become apparent from the dependent claims and the embodiments that are shown merely for illustrative purposes. For this purpose the drawings show to some extent in schematic form in:

(2) FIG. 1: a system of an arrangement according to one embodiment of the present invention; and

(3) FIG. 2: a method according to one embodiment of the present invention.

DETAILED DESCRIPTION

(4) FIG. 1 shows an arrangement of a robot, of which FIG. 1 shows only two drives 23, 33 as representative examples thereof, and a system for operating this robot, according to one embodiment of the present invention. FIG. 2 shows a method for operating this robot according to one embodiment of the present invention, where in this case the method is carried out by means of the system that is configured in software and hardware for this purpose.

(5) The system comprises a machine control system 10 with drive control units 13A, 13B, which control the drives 23, 33.

(6) Furthermore, the system comprises a fail-safe control system with a first channel 100 and a redundant, in particular, dissimilar, second channel 200, which monitors the robot.

(7) In a first step S10 (see FIG. 2) a means 11 of the machine control system 10 determines, on the basis of a specified control program, in particular, by means of path planning and/or interpolation, target reference position values x for the TCP of the robot.

(8) From these target reference position values x for the TCP a means 12 of the machine control system 10 determines, on the basis of a reverse transformation between the reference position values of the TCP and the axial position values, the target axial position values q, as indicated by means of the data flow 11x.fwdarw.12 in FIG. 1.

(9) As an alternative, in step S10 the means 11 can also determine the target reference position values x for the TCP on the basis of a forward transformation between the reference position values of the TCP and the preset target axial position values q, which are specified, for example, by means of manually moving an axis of the robot, as indicated by means of the data flow 12q.fwdarw.11 in FIG. 1.

(10) The first and second channels 100, 200 receive the target reference position values x for the TCP as the first input target values x.sub.s and the target axial position values q as the second input target values q.sub.s. In one embodiment the first input target values x.sub.s may also comprise, in addition or as an alternative, first and/or higher time derivatives of the target reference position values x. In addition or as an alternative, the second input target values q.sub.s may also comprise, in addition or as an alternative, first and/or higher time derivatives of the target axial position values q.

(11) In addition, the drive control units 13A, 13B receive from the means 12 the corresponding components of the target axial position values q.

(12) In one exemplary embodiment an acquisition means comprises by way of an example two resolvers each 21, 22 or 31, 32 per drive 23, 33.

(13) The first resolver 21 determines the actual axial position values q21 for the actual axial position of the drive 23. The second resolver 22 determines in a redundant manner the actual axial position values q22 for the actual axial position of the drive 23. The third resolver 31 determines the actual axial position values q31 for the actual axial position of the drive 33. The fourth resolver 32 determines in a redundant manner the actual axial position values q32 for the actual axial position of the drive 33.

(14) The first channel 100 receives the actual axial position values q21, q31; and the second channel 200 receives the redundantly determined actual axial position values q22, q32 as the second input actual values. In one embodiment these second input actual values may also comprise, in addition or as an alternative, first and/or higher time derivatives of the actual axial position values.

(15) The drive control units 13A, 13B also receive one each of these actual axial position values q21 or q22 and/or q31 or q32 respectively and determine from them the lag errors A between the target axial position values and the actual axial position values. On the basis of these lag errors said drive control units control the drives 23, 33.

(16) The first and second channels 100, 200 receive these lag errors A that have been determined by the drive control units 13A, 13B.

(17) The means 11 receives one each of the actual axial position values q21, q31 and the lag error .

(18) On the basis of the forward transformation between the reference position values of the machine-fixed reference and the axial position values, the means 11 determines the first input actual value x.sub.i. At the same time said means determines these input actual values x.sub.i on the basis of the lag error by not forward transforming the determined actual axial position values q21, q31, but rather by first adding to them the corresponding component of the lag error and then forward transforming this sum (x.sub.i=T.Math.{[q21, q31, . . . ]+} with the forward transformation matrix T).

(19) The first and second channels 100, 200 receive these respective first input actual values x.sub.i. In one embodiment the first input actual values x.sub.i may also comprise, in addition or as an alternative, first and/or higher time derivatives of the actual reference position values x.

(20) Thus, in step S10 the first and second channels 100, 200 receive the respective

(21) first input target values x.sub.s;

(22) second input target values q.sub.s;

(23) first input actual values x.sub.i and

(24) second input actual values q21, q31 and/or q22, q32 as well as lag error .

(25) In a step S20 a means 111 of the first channel 100 compares the first reference target values, which depend on the first input target values, and the first reference actual values, which depend on the first input actual values, with each other. In the exemplary embodiment the first reference target values correspond to the first input target values x.sub.s; and the first reference actual values correspond to the first input actual values x.sub.i. In a modification the means 111 may determine, in addition or as an alternative, the first reference target values and the first reference actual values by means of a time differentiation, especially if the first input target values or the first input actual values, which are received from the means 11 of the machine control system 10, do not include any corresponding time derivatives.

(26) In the event that a deviation between the first reference target values and the first reference actual values exceeds a specified tolerance (S20: Y), the means 111 of the first channel 100 of the fail-safe control system triggers a fault reaction, which is indicated by an interruption in the power supply, shown in bold type, of the drives 23, 33 in FIG. 1.

(27) A means 211 of the second channel 200 compares in a redundant manner the first reference target values, which depend on the same first input target values in the same way as in the first channel, and the first reference actual values, which depend on the same first input actual values in the same way as in the first channel, with each other. As a result, in the exemplary embodiment these first reference target values of the second channel also correspond to the first input target values x.sub.s; and these first reference actual values of the second channel correspond to the first input actual values x.sub.i. Correspondingly, in one modification the means 211 may also determine, in addition or as an alternative, the first reference target values and the first reference actual values by means of a time differentiation, especially if the first input target values and/or the first input actual values, which are received from the means 11 of the machine control system 10, do not include any corresponding time derivatives.

(28) In the event that a deviation between these first reference target values and first reference actual values of the second channel 200 exceeds the same specified tolerance (S20: Y), the means 211 of the second channel 200 of the fail-safe control system triggers the same fault reaction, which is indicated in an analogous manner by means an interruption in the power supply of the drives 23, 33 in FIG. 1.

(29) In a step S30 a means 112 of the first channel 100 compares the second reference target values, which depend on the second input target values q.sub.s; and the second reference actual values, which depend on the second input actual values q21, q31, with each other. In the exemplary embodiment the second reference target values correspond to the second input target values q.sub.s, whereas the second reference actual values are determined, on the basis of the second input actual values q21, q31 and the lag error by adding them together. In one modification the means 112 may determine, in addition or as an alternative, the second reference target values and the second reference actual values by means of a time differentiation, especially if the second input target values and/or the second input actual values, which are received from the means 12 of the machine control system 10, do not include any corresponding time derivatives.

(30) In the event that a deviation between the second reference target values and the second reference actual values exceeds a specified tolerance (S30: Y), the means 112 of the first channel 100 of the fail-safe control system triggers the same fault reaction, which is indicated in an analogous manner by means of an interruption in the power supply in FIG. 1.

(31) A means 212 of the second channel 200 compares in a redundant manner the second reference target values, which depend on the same second input target values q.sub.s in the same way as in the first channel, and the second reference actual values, which depend on the second input actual values q22, q32, which are determined in a redundant manner, in the same way as in the first channel, with each other. As a result, in the exemplary embodiment these second reference target values of the second channel also correspond to the second input target values q.sub.s, whereas these second reference actual values of the second channel are determined on the basis of the second input actual values q22, q32 and the lag error by adding them together. In one modification the means 212 may determine, in addition or as an alternative, the second reference target values and the second reference actual values by means of a time differentiation, especially if the second input target values and/or the second input actual values, which are received from the means 12 of the machine control system 10, do not include any corresponding time derivatives.

(32) In the event that a deviation between these second reference target values and second reference actual values exceeds a specified tolerance (S30: Y), the means 212 of the second channel 200 of the fail-safe control system triggers the same fault reaction, which is indicated in an analogous manner by means an interruption in the power supply in FIG. 1.

(33) In a step S40 the first and second channels 100, 200 compare in each case the reference target values and/or the reference actual values with, in particular, the variable, preset threshold values X.sub.0 and trigger the same or a different fault reaction, in the event that a deviation between the reference values and the threshold values exceeds a specified tolerance (S40: Y).

(34) FIG. 1 shows as an example of the aforesaid that the means 111, 211 of the first and second channels 100, 200 are specified, for example, an allowable Cartesian working space X.sub.0 and compare the reference actual values, which correspond to the actual reference position values x.sub.i, received from the means 11, with said working space. As a result, when the TCP leaves this specified working space, said means trigger a fault reaction, for example move the robot into a safer pose (FIG. 2: SAFE).

(35) Even though exemplary embodiments are explained in the description above, it should be pointed out that a plurality of modifications are possible. Moreover, it should be pointed out that the exemplary embodiments are merely examples that do not restrict the scope of protection, the applications and configuration in any way. Instead, the description above gives the person skilled in the art a guideline for implementing at least one exemplary embodiment. At the same time it is possible to make diverse modifications, in particular, with respect to the function and the arrangement of the components described without departing from the scope of protection that will become apparent from the claims and the combination of features equivalent thereto.

LIST OF REFERENCE NUMERALS

(36) 10 machine control system 11, 12 means of the machine control system 13A, 13B drive control unit 21, 22 resolver 23 drive 31, 32 resolver 33 drive 100 first channel 111, 112 means of the first channel 200 second channel 211, 212 means of the second channel