Method for verifying the assignment of a drive to a control device

Abstract

A method for verifying the assignment of a drive to a control device of an industrial robot. A drive, comprising at least one actuator and a motion sensor, is assigned to one of the axles of the robot. The assignment is verified by outputting a suitable test signal from the control device to the drive, and comparing the output test signal with motion signals generated by the motion sensor.

Claims

1. A method for verifying an assignment of a plurality of drives of a machine having a plurality of axles to a control device, wherein each of the plurality of drives is assigned to a corresponding one of the axles and comprises a triggering device, an actuator and a motion sensor, wherein the control device is coupled to each of the triggering devices and the motion sensors via associated signal lines, and wherein the control device is configured to control the machine by means of a control program, the method comprising: a) the control device outputting a test signal to the triggering device of one of the drives; b) in response to the test signal, the triggering device actuating the actuator of the one drive to move a corresponding axle to which the one drive is assigned, wherein the test signal comprises a periodic signal decreasing and increasing in amplitude to cause the corresponding axle to move in respective directions alternatingly aligned with an additional applied external force and against the additional applied external force, and wherein a slope of an amplitude of the test signal indicates whether the additional applied external force is aligned with or against a direction of movement of the corresponding axle; c) the motion sensor of the one drive detecting movements of the axle both in directions with or against the additional applied external force, and sending a corresponding motion signal to the control device, and d) the control device comparing the test signal with the corresponding motion signal to detect at least one of a cross of the signal lines coupling the control device to the triggering device or a cross of the signal lines coupling the control device to the motion sensor, wherein in comparing the test signal with the corresponding motion signal to detect the at least one cross, the comparison includes at least one of a step of detecting an inversion of the corresponding motion signal relative to the test signal or a step of detecting an alternate indicator of a direction of the additional applied external force with or against the movement of the axle that is opposite to the direction indicated by the slope of the amplitude of the test signal.

2. The method according to claim 1, wherein the test signal includes at least one of different accelerations, different speeds, or different paths to be traversed in the respective directions alternatingly aligned with the additional applied external force and against the additional applied external force.

3. The method according to claim 1, wherein the control device repeats the steps a) to d) for each of the plurality of drives.

4. The method according to claim 1, wherein the test signal has a period that is at least twice as longer as a period associated with a maximum phase shift value.

5. The method according to claim 1, further comprising the step of the control device generating a message that at least one of a cross of the signal lines coupling the control device to the triggering device or a cross of the signal lines coupling the control device to the motion sensor has been detected.

6. The method according to claim 1, wherein: the additional applied external force is a gravitational force, and the step of detecting an alternate indicator comprises the step of detecting an indicator of a level on energy consumption for the actuator of the at least one drive.

7. The method according to claim 1, wherein the test signal triggers a movement amplitude of a link of the machine, which is less than 1 cm or triggers a rotational movement of the link which is less than 1 degree.

8. The method according to claim 1, further comprising the step of the control device comparing the test signal with the corresponding motion signal in order to measure at least one of a phase shift or a change in amplitude, wherein target values of the phase shift or the change in amplitude are known for each drive, and wherein the control device compares the measured phase shift or the change in amplitude with the target values of for the drive.

9. The method according to claim 1, wherein the machine comprises a robot.

10. The method according to claim 7, wherein the movement amplitude is less than 0.5 cm.

11. The method according to claim 7, wherein the movement amplitude is less than 1 mm.

12. The method according to claim 7, wherein the rotational movement is less than 0.5 degrees.

13. The method according to claim 7, wherein the rotational movement is less than 0.1 degrees.

14. The method according to claim 9, wherein the machine comprises an articulated-arm robot.

15. A machine having a plurality of driven axles and a control device configured to control the machine by means of a control program, wherein the control device is configured to verify an assignment of a plurality of drives to the plurality of axles, wherein each of the plurality of drives is assigned to one of the axles and comprises a triggering device, an actuator and a motion sensor, each drive being further assigned to the control device, wherein: the control device is configured to output a test signal to the triggering device of one of the drives, the triggering device is configured, in response to the test signal, to actuate the actuator of the one drive to move a corresponding axle to which the one drive is assigned, wherein the test signal comprises a periodic signal decreasing and increasing in amplitude to cause the corresponding axle to move in respective directions alternatingly aligned with an additional applied external force and in a direction against the additional applied external force, and wherein a slope of an amplitude of the test signal indicates whether the additional applied external force is aligned with or against the direction of movement of the axle, the motion sensor of the one drive is configured to detect movements of the axle both in directions with or against the additional applied external force, and send a corresponding motion signal to the control device; and the control device is further configured to compare the test signal with the corresponding motion signal to detect at least one of a cross of the signal lines coupling the control device to the triggering device or a cross of the signal lines coupling the control device to the motion sensor, wherein in comparing the test signal with the corresponding motion signal to detect at least one cross, the comparison includes at least one of a step of detecting an inversion of the motion signal relative to the test signal or a step of detecting an alternate indicator of a direction of the additional applied external force with or against the movement of the axle that is opposite to the direction indicated by the slope of the amplitude of the test signal.

16. The machine according to claim 15, further comprising the step of the control device generating a message that at least one of a cross of the signal lines coupling the control device to the triggering device or a cross of the signal lines coupling the control device to the motion sensor has been detected.

17. A non-transitory computer-readable storage medium on which instructions are stored, which, when loaded to a control device and executed, perform a method for verifying an assignment of a plurality of drives of a machine having a plurality of axles, wherein each of the plurality of drives is assigned to one of the axles and comprises a triggering device, an actuator and a motion sensor, wherein the control device is coupled to each of the triggering device and the motion sensor via associated signal lines, and wherein the control device is configured to control the machine by means of a control program, the method comprising: a) the control device outputting a test signal to the triggering device of one of the drives; b) in response to the test signal, the triggering device actuating the actuator of the one drive to move a corresponding axle to which the one drive is assigned, wherein the test signal comprises a periodic signal decreasing and increasing in amplitude to cause the corresponding axle respectively to move in respective directions alternatingly aligned with an additional applied external force and in a direction against the additional applied external force, and wherein a slope of an amplitude of the test signal indicates the respective direction of the additional applied external force as being with or against a direction of movement of the axle; c) the motion sensor of the one drive detecting the movements of the axle in both directions with or against the additional applied external force, and sending a corresponding motion signal to the control device; and d) the control device comparing the test signal with the corresponding motion signal to detect at least one of a cross of the signal lines coupling the control device to the triggering device or a cross of the signal lines coupling the control device to the motion sensor, wherein in comparing the test signal with the corresponding motion signal to detect at least one cross, the comparison includes at least one of a step of detecting an inversion of the motion signal relative to the test signal or a step of detecting an alternate indicator of a direction of the additional applied external force with or against the movement of the axle that is opposite to the direction indicated by the slope of the amplitude of the test signal.

Description

4. DESCRIPTION OF PREFERRED EMBODIMENTS

(1) In the following, preferred embodiments will be explained in more detail with reference to the accompanying figures. In the figures,

(2) FIG. 1 shows an industrial robot as a preferred embodiment of a machine having a control device;

(3) FIG. 2 shows a schematic representation of a closed control loop of a drive;

(4) FIG. 3 shows an exemplary assignment of a plurality of drives to a control device;

(5) FIG. 4 shows a periodic test signal and a motion signal having a phase shift and a change in amplitude;

(6) FIG. 5 shows a periodic sawtooth-like test signal and a motion signal having an inversion;

(7) FIGS. 6A-6E show the periodic sawtooth-like test signal of FIG. 5 and corresponding motion signals and signals indicative of the energy consumption of the actuator; and

(8) FIG. 7 shows a periodic test signal and a motion signal having a phase shift, a change in amplitude as well as a change of the slopes slope.

(9) FIG. 1 shows an industrial robot 1 with an associated control device 100. Via the control signals P.sub.o, the drives of the industrial robot assigned to the axles A1-A6 can be controlled. In response to the controlling control signal, the actuator of the respective drive causes corresponding movements of the links 2 of the industrial robot 1. These movements are detected by the motion sensors and a motion signal P.sub.i is returned to the control device.

(10) FIG. 2 shows a schematic closed control loop of a drive. The control program P here provides the actual values of the movement to be executed by the industrial robot 1 and causes the control device 100 to send control signals P.sub.o to the drive 10. The drive preferably comprises at least one control device 200, at least one actuator 300, and at least one motion sensor 400. The triggering device may also be integrated in the control device. However, the risk of an incorrect assignment of the actuators remains due to the integration of the control device and, as a result, the method is applicable analogously.

(11) The triggering device 200 controls the actuator 300 based on the control signals P.sub.o. If electric motors are used, the triggering device 200 provides the motor current, for example. For hydraulic or pneumatic actuators, the volume flow or the pressure is controlled accordingly. The movements of the links of the industrial robot 1 initiated by the actuator 300 are detected by the motion sensors 400 and corresponding motion signals P.sub.i are sent to the control device 100, thus closing the control loop. Preferably, the amplitude of the test signal is selected such that the amplitude of movement of the moving link in the event of translational movement is less than 1 cm, preferably less than 0.5 cm, and more preferably less than 1 mm, and, in the case of a rotational movement of the link, is less than 1 degree, preferably less than 0.5 degrees, and more preferably less than 0.1 degrees.

(12) FIG. 3 shows an exemplary assignment of a plurality of drives (here: four drives) to a control device 100. The control device 100 here comprises, for example, at least four signal outputs o.sub.1-o.sub.4 and four signal inputs i.sub.1-i.sub.4. Via signal outputs o.sub.1-o.sub.4, the control signals or the test signals are sent to the four triggering devices 201-204 of the four drives and the four actuators 301-304 are controlled accordingly. The motion sensors 401-404 detect the movement and send the motion signals to the control device 100 via the signal inputs i.sub.1-i.sub.4. The individual drives in the illustrated embodiment are each comprised of one control device 20x, one actuator 30x, and one sensor 40x. The variable x can accordingly have the values 1-4 and thus defines the individual drives x=1-4. A correct assignment of the drives to the control device 100 is given if the drive x=1 is assigned to the I/O pair (i.sub.1, o.sub.1) and the drives x=2-4 are assigned accordingly. Furthermore, for a correct assignment, the signal lines 3 must not cross. This representation corresponds to an inversion. The exemplary assignment of FIG. 3 shows inversions of the signal lines 3, which occur between the signal outputs o.sub.1-o.sub.4 and the drives (actuator-side) and between the motion sensors and the signal inputs i.sub.1-i.sub.4 (sensor-side). A double inversion occurring on only one drive (see x=3) is also possible. In addition, the drives (x=1-4) may be assigned to the incorrect I/O pairs (interchanged), as shown for the drives x=1, 2.

(13) FIG. 4 shows a periodic test signal P.sub.1,o and a motion signal P.sub.1,i. Test signal P.sub.1,o is shown as a solid line while the motion signal P.sub.1,i is shown as a broken line. As this shows, the drive, which comprises at least one actuator and one motion sensor, represents a system-theoretically sufficient linear transmission link. The motion signal P.sub.1,i which is dependent on the test signal P.sub.1,o, appears at the signal input of the control device with a changed amplitude k and a phase shift . The test signal as well as the motion signal have the period T. The periodic test signal P.sub.1,o shown has similar rising and falling slopes. In order to distinguish between a phase shift and an inversion of the motion signal, the period T in this case is chosen to be longer than twice the maximum occurring phase shift (T>2).

(14) FIG. 5 shows a particularly preferred sawtooth-like, periodic test signal P.sub.2,o and a corresponding (i.e., resulting) motion signal P.sub.2,i, wherein the motion signal P.sub.2,i here has an inversion. The test signal P.sub.2,o is shown as a solid line while the motion signal P.sub.2,i is shown as a broken line. The use of a sawtooth-like periodic test signal, such as a sawtooth signal, allows for the detection of a signal inversion regardless of the phase shift, making sawtooth-like periodic test signals particularly advantageous. The sawtooth-like periodic test signals are favorable in that the rising and falling slopes are formed differently. In particular, they have different slopes.

(15) The test signals of FIGS. 4 and 5 are particularly helpful for the case regularly occurring in practice in which an incorrect assignment of the motion sensors is excluded for other reasons and only the correct assignment of the actuators is to be verified. The person skilled in the art will appreciate that, in such cases, the signal does not necessarily have to be periodic, but that a single test signal with a rising and a falling slopes may be sufficient.

(16) FIGS. 6A-6E show the periodic sawtooth-like test signal of FIG. 5 and corresponding motion signals as well as signals S.sub.E,i indicative of the energy consumption of the actuator. The signals S.sub.E,i, indicative of the energy, may be representative, for example, of the motor current of an actuator. Preferably, these signals S.sub.E,i, indicative of the energy consumption of the actuator 300, are additionally provided to the control device 100. The control device 100 compares these signals S.sub.E,i with the motion signals P.sub.2,i and the test signal P.sub.2,o in order to detect the directions of movement of the actuator 100 independently of the motion signals P.sub.2,i in axles under the effect of gravity. Thus, an inversion of the signal lines can be detected both on the sensor-side, as well as on the actuator-side.

(17) If an inversion of the signal line is detected, it is important in some cases to determine whether the inversion occurs on the sensor-side or on the actuator-side. While actuator-inversions may cause an incorrect direction of movement, sensor-side inversions result in incorrect direction of movement information. For a correct assignment of the drive, both cases of inversions must be distinguishable. Furthermore, it is advantageous to be able to also detect double inversions, i.e., an inversion occurring simultaneously on the actuator-side and the sensor-side on only one drive, namely in the cases where a sensor-side inversion cannot be excluded in other ways. In the case of a double inversion, a seemingly correct motion signal is returned to the control device 100. Such a case is shown on drive x=3 in FIG. 3. The distinction between the individual inversion cases is shown in FIGS. 6B-6E and explained below:

(18) FIG. 6A shows a sawtooth-like test signal P.sub.2,o, wherein the test signal is the basis for the motion signals P.sub.2,i shown in FIGS. 6B-6E. The test signal P.sub.2,o can specify the motor speed, for example. The shown signal S.sub.E is a signal indicative of the energy consumption of the actuator, which would occur in the form shown if the drive drove an axle not subjected to gravity. It is therefore a fictitious signal. This fictitious signal S.sub.E is shown as a dotted line as a reference value in the FIGS. 6B-6E. The required energy of the actuator for a rising slopes of the test signal is lower than for a falling slopes since the rising slopes is flatter. This represents, for example, a lower speed of movement (or lower speed of the motor). For the explanation of FIGS. 6B-6E, it is assumed that the actuator moves the axle against the force of gravity with the rising slopes 4 (see FIG. 5) of the test signal P.sub.2,o. Consequently, the axle moves with gravity with the falling slopes 5.

(19) FIGS. 6B-6E show the motion signals P.sub.2,i and the signals S.sub.E,i of the drive, which are indicative of energy, for an axle subjected to gravity. Herein, FIG. 6B shows an assignment of the drive without inversion, FIG. 6C shows an assignment of the drive with sensor-side inversion, FIG. 6D shows an assignment of the drive with actuator-side inversion, and FIG. 6E shows an assignment of the drive with a double inversion. It turns out that all the cases are distinguishable based on the signals P.sub.2,i and S.sub.E,i. For the purpose of simplification, the representation of a phase shift and a change in amplitude has been omitted. However, these may occur regardless of the described method.

(20) As shown in FIG. 6B, a correct assignment results in a motion signal P.sub.2,i corresponding the test signal P.sub.2,o. The signal S.sub.E,i, indicative of energy, however, differs from the fictitious signal S.sub.E. This is because the actuator uses more energy when the axle is moved against gravity than if the axle is not subject to gravity. While the actuator is moving the axle against gravity, which corresponds to the rising slopes of the test signal P.sub.2,o, the actuator is thus provided with more energy. The level of the signal S.sub.E,i is consequently higher than the fictitious signal S.sub.E. Accordingly, the level of the signal S.sub.E,i for the falling slopes of the test signal P.sub.2,o is below the fictitious signal S.sub.E, which corresponds to a movement of the axle with the force of gravity. Gravity therefore supports the movement of the actuator so that less energy is consumed.

(21) The sensor-side inversion shown in FIG. 6C results in a signal S.sub.E,i, indicative of energy, that is identical to that shown in FIG. 6B since the drive actually performs the same movement due to the test signal P.sub.2,o. The energy requirement is therefore equal. However, due to the inversion of the signal line of the motion signal P.sub.2,i, an inverted motion signal P.sub.2,i results.

(22) The actuator-side inversion shown in FIG. 6D results in an inverted motion signal P.sub.2,i. However, the inversion can be distinguished from the sensor-side inversion due to the different form of the signal S.sub.E,i, indicative of energy. This is reflected in the comparison of the signal S.sub.E,i, indicative of energy, and the fictitious signal S.sub.E. The actual energy consumption of the actuator for the commanded direction of movement against gravity (rising slopes) is lower than that assumed by the fictive signal. I.e., even though the test signal P.sub.2,o requests a movement against gravity, less energy is required by the actuator. A comparison between S.sub.E,i and S.sub.E shows that the actuator must be connected incorrectly, regardless of the signal the motion sensor outputs.

(23) FIG. 6E shows the case of double inversion. Here the motion signal P.sub.2,i corresponds to the test signal P.sub.2,o. However, the signal S.sub.E,i, indicative of energy, is formed as shown in FIG. 6D. The direction of movement against gravity according to the signal S.sub.E,i, indicative of energy, would require less energy than the reference signal S.sub.E, presenting a contradiction. This can be detected by the control device and indicates that the actuator is connected incorrectly.

(24) With the cases shown in FIGS. 6A-6E, not only is it possible to detect an occurring inversion. Rather, it is also possible to distinguish between actuator-side and sensor-side inversions. Thus, the point where the inversion is occurring can be determined.

(25) FIG. 7 shows a periodic test signal P.sub.3,o and a motion signal P.sub.3,i, having a phase shift, a change in amplitude, as well as a change of the slope incline. The evaluation of the slopes slope can be used to detect the directions of movement of the actuator 100 independently of a signal, indicative of energy, in spite of occurring inversions.

(26) According to this embodiment, at least one axle A1-A6 of the industrial robot 1 is an axle subjected to gravity or is subject to a force for the purpose of verifying the correct assignment. The control device 100 compares the slope of the corresponding slopes of the test signal P.sub.3,o and the motion signal P.sub.3,i.

(27) The test signal P.sub.3,o is shown as a solid line in FIG. 7 while the motion signal P.sub.3,i is shown as a broken line. The test signal P.sub.3,o can specify an actuator moment, for example. The motion signal P.sub.3,i preferably reflects a speed. A change of the slope incline in the motion signal indicates a force acting alongside the actuator moment because the moving link is accelerated in the direction of the force or is decelerated by the force. The actuator moment is the moment generated by the actuator. The additional acting force is gravity, for example, or a force applied to the drive. The control device 100 compares the slope of the corresponding slopes of the test signal P.sub.3,o and the motion signal P.sub.3,i. If a deviation of the slopes slope is detected, it can be inferred that the drive subjected to an additional force. In the case of a steeper slope of the motion signal P.sub.3,i the drive is substantially moved with the additional force and, in the case of a flatter slopes, it is substantially moved against the acting additional force. Analogously to the explanations for FIG. 6A-6E, it is thus possible to detect the location of the inversion within the assignment of a drive as well as detect double inversions (see drive x=3, FIG. 3).

(28) In an advantageous development, the control device 100 transfers the determined assignment of drives x=1-4 and of the motion sensors 401-404 to the control program P. In the control program P, the saved assignment is changed accordingly so that the correct assignment is not made by changing the connection of the drives or motion sensors on the control device. This can compensate for an interchange and an inversion of the signal lines. The machine or the robot is not limited to a certain number of drives and motion sensors, but rather adapts to any number of drives, the assignment of which to a control device can be determined by the method.

(29) It should be noted that the invention claimed herein is not limited to the described embodiments, but may be otherwise variously embodied within the scope of the claims listed infra.

5. REFERENCE NUMBER LIST

(30) 1: industrial robot 2: link 3: signal line 4: rising slopes 5: falling slopes 10: drive 100: control device 200: triggering device 201-204: triggering devices 300: actuator 301-304: actuators 400: motion sensor 401-404: motion sensors A1-A6: axles i.sub.1-i.sub.4: signal inputs of the control device o.sub.1-o.sub.4: signal outputs of the control device P.sub.o: control signal P.sub.1,o; P.sub.2,o: periodic test signal P.sub.3,o: periodic, sawtooth-like test signal P.sub.i: motion signal P.sub.1,i-P.sub.3,i: motion signals S.sub.E: signal-energy consumption of the actuator S.sub.E,i: signal-energy consumption of the actuator when subjected to gravity k: change in amplitude T: period phase shift