Device for controlling the operation of driving apparatus

• US 6,563,281 B1
• Filed: 07/16/2001
• Issued: 05/13/2003
• Est. Priority Date: 01/19/1999
• Status: Expired due to Fees

• Current Assignee: ABB AB (ABB Limited)
• Original Assignee: ABB AB (ABB Limited)
• Inventors: Ramström, Karl-Gustav, Brogårdh, Torgny
• Primary Examiner(s): Ro, Bentsu
• Application Number:
  US09/889,285
• Time in Patent Office: 666 Days
• Field of Search: 318/564, 318/565, 318/434, 388/903, 388/909
• US Class Current: 318/564
• CPC Class Codes: B25J 19/066 Redundant equipment
• CPC Class Codes: Y10S 388/903 Protective, e.g. voltage or current limit
• CPC Class Codes: Y10S 388/909 Monitoring means

Abstract

A device for monitoring operation of a driving arrangement including at least a servo-mechanism, which includes a regulator, a driving motor controlled by the regulator, and an element which can be set in motion by the driving motor. A detection arrangement detects deviations between intended and actual movement positions of the element and an operation inhibiting and/or alarming arrangement inhibits operation of the driving arrangement and/or starts an alarm when impermissible deviations are detected. The monitoring device includes a redundant driving arrangement, which include at least one auxiliary servomechanism including a redundant regulator, a redundant driving motor controlled by the redundant regulator, and a redundant element which can be set in motion by the redundant driving motor. The regulator and the redundant regulator are connected to an arrangement delivering control information or imparting to the element and the redundant element the same movements or movements having a predetermined relation to each other. The detection arrangement is arranged to detect the deviations concerning the relative position or movements of the element or an object connected thereto, and the redundant element.

Claims

1. A device for monitoring an operation of a driving arrangement comprising at least one servo mechanism, which includes a regulator, a driving motor controlled by this regulator and an element which can be set in motion by the driving motor, a detection arrangement for detecting deviations between intended and actual movement positions of the element and an operation inhibiting and/or alarming arrangement for inhibiting the operation of the driving arrangement and/or starting an alarm when impermissible deviations have been established by the detection arrangement, the device comprising a redundant driving arrangement, which comprises at least one redundant servomechanism, including a redundant regulator, a redundant driving motor controlled by this redundant regulator and a redundant element which can be set in motion by this redundant driving motor, wherein the regulator and the redundant regulator are connected to an arrangement delivering control information for imparting to the element and the redundant element same movements or movements having a predetermined relation to each other, and that the detection arrangement is arranged to detect deviations concerning the relative position or movements of the element, or an object connected thereto, and the redundant element.

2. A device according to claim 1, wherein the detection arrangement comprises contact members in contact with each other in a contact point, which contact members detect deviations between the element which can be set in motion by the driving motor and the redundant element.

3. A device according to claim 2, wherein the detection arrangement comprises electronic circuits or a computer for obtaining a contact point by comparison between an output signal from an angle or position sensor, connected to the element to be monitored, and an output signal from members, comprised in the detection arrangement, being arranged to emit an output signal corresponding to a position of the redundant element.

4. A device according to claim 3, wherein the output signal from the detection arrangement represents a simulation of the redundant driving motor and the redundant element driven by said motor, which simulation has been obtained by electronic circuits or one or several computers.

5. A device according to claim 3, wherein the simulation of the redundant driving motor is dimensioned for obtaining same dynamic characteristics as the driving motor with associated elements which can be set in motion by said motor.

6. A device according to claim 3, wherein the detection arrangement comprises detection members in a form of angle or position sensors associated with the element and the redundant element, respectively, and a difference former connected to these sensors, and an output signal from this difference former is supplied to a comparator, a comparating signal of which simulates a half of a permitted relative movement or position differential between the element and the redundant element or objects connected to these.

7. A device according to claim 6, further comprising a signal generator configured to generate a monitor signal to the regulator in the servomechanism for the element and to supply a monitor signal offset in phase to the regulator in the servomechanism for the simulated redundant element, and the detection arrangement is arranged to use this monitor signal for securing that no errors will ensue simultaneously as concerns driving of the element as well as the simulated redundant element and that no errors will ensue in the electronic circuits included in the difference former, the comparator, and the detection arrangement.

8. A device according to claim 2, wherein the members being in contact with each other in the contact point comprise electrically conducting members, one member of which, directly or via transmissions, follows movements of the element, and a second member of which, directly or via transmissions, follows movements of the redundant element.

9. A device according to claim 8, wherein at least one of said electrically conducting members is surrounded by a medium, being insulating to electric current, in such a way that a deviation in movements between the element and the redundant element results in that that electrical contact in the contact point is interrupted and that the driving motor is disengaged and/or is braked by the operation inhibiting arrangement.

10. A device according to claim 8, wherein one of the electrically conducting members comprises a conducting surface surrounded by an insulating surface, and two other conducting members, connected in series, are pressed against the conducting surface so as to close an electric circuit, in which circuit a breaker for the driving motor is included.

11. A device according to claim 8, wherein electrically conducting members in to or more contact points are connected in series.

12. A device according to claim 2, wherein plural contact points are provided and an arrangement is such that a successive change of contact points takes place during relative movements of the element and the redundant element.

13. A device according to claim 2, wherein at least one contact point is located on a linkage system between the element and the redundant element.

14. A device according to claim 2, wherein the contact point is mechanically connected to an electric contact.

15. A device according to claim 2, wherein the contact point is mechanically connected to a holding mechanism for a brake or an electric breaker included in the operation inhibiting arrangement.

16. A device according to claim 2, wherein said contact point is formed of a pneumatic coupling.

17. A device according to claim 16, further comprising plural measuring points and moirè

-technique for measuring deviations between the movements of the element and the redundant element.

18. A device according to claim 2, wherein said contact point is formed between a sensor and a sensor target and the detection arrangement comprises a non-contact measuring system.

19. A device according to claim 18, wherein the measuring system utilizes inductive, capacitive, optical, or ultrasonically based sensors.

20. A device according to claim 18, wherein the redundant driving arrangement is arranged to make the redundant element oscillate or a sensor for the redundant element is arranged to be electrically modulated at least one frequency, and the detection arrangement is arranged to use the signal/signals, thus obtained, as monitor signal/signals for testing the monitoring device.

21. A device according to claim 18, wherein the contact point is moveable and is defined by a pattern arranged to move connected to the movements of either the element or the redundant element.

22. A device according to claim 21, wherein a sensor in the redundant element is arranged to be moved in a path corresponding to said pattern when the movements of the element and the redundant element are synchronized.

23. A device according to claim 2, further comprising a signal generator configured to generate a monitor signal to the regulator in the servomechanism for the element and to the regulator of the redundant servomechanism for the redundant element, and that the monitor signal, transmitted in two ways, is used for monitoring if errors ensue simultaneously as concerns driving of the element and the redundant element.

24. A device according to claim 2, wherein the contact point is electromagnetically connected to driving circuits for the driving motor of the element and/or a brake for said motor.

25. A device according to claim 1, wherein the driving arrangement forms part of a manipulator of an industrial robot, and that the element which can be set in motion by the motor comprises an arm of the manipulator.