Method for monitoring a drive device for a standstill condition, monitoring system therefore, and drive system therefore

• US 7,482,771 B2
• Filed: 10/10/2005
• Issued: 01/27/2009
• Est. Priority Date: 10/18/2004
• Status: Active Grant

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Hahn, Ulrich, Schwesig, Günter
• Primary Examiner(s): Leykin; Rita
• Application Number:
  US11/577,425
• Publication Number:
  US 20080088267A1
• Time in Patent Office: 1,205 Days
• Field of Search: 318/272, 318/599, 318/612, 187/247, 187/248, 187/224, 187/276, 187/209
• US Class Current: 318/272
• CPC Class Codes: B66B 5/0031 for safety reasons
• CPC Class Codes: G05B 19/19 characterised by positioning or contouring control systems, e.g. to control position from one programmed point to another or to control movement along a programmed continuous path
• CPC Class Codes: G05B 19/4062 Monitoring servoloop, e.g. overload of servomotor, loss of feedback or reference

Abstract

In a method for monitoring a stationary condition of a drive device, a monitoring device provides the drive device with a temporally varying monitoring signal which, when a sensor device connected to the drive device functions properly, modulates a sensor output signal of the sensor device in accordance with the monitoring input signal. The monitoring device receives the sensor signal and monitors it for the presence of a corresponding signal component. In the absence of such a signal component, the monitoring device controls a safety device which converts the drive device into a safe state. When the drive device is controlled by means of at least two phase-shifted current regulators, it is possible for the monitoring device to monitor an output signal of at least one of the current regulators for constancy and to control the safety device when the output signal of the at least one current regulator changes.

Claims

1. A method for monitoring a drive device, comprising the steps of:

providing a monitoring device to apply a monitoring input signal, which changes over time, to a drive device at a standstill;

modulating commensurate with the monitoring input signal a sensor output signal of a sensor device, which is connected to the drive device, in response to the monitoring input signal, when the sensor device functions properly;

wherein the monitoring device receives the sensor output signal;

wherein the monitoring device monitors the sensor output signal for the presence of a signal component which corresponds to the monitoring input signal; and

wherein the monitoring device activates a safety device to transfer the drive device into a safe state, when the monitoring device ascertains the absence of the signal component corresponding to the monitoring input signal.

2. The monitoring method of claim 1, wherein the monitoring device executes the monitoring method only when the drive device is not in motion, with the exception of a movement caused by the monitoring input signal.

3. The monitoring method of claim 1, wherein the monitoring device executes the monitoring method only when the drive device has not been moved over a time span which is greater than a wait time.

4. The monitoring method of claim 1, wherein the drive device is controlled by means of a controller.

5. The monitoring method of claim 4, wherein the monitoring device impresses the monitoring input signal onto an input signal of the controller.

6. The monitoring method of claim 4, wherein the monitoring device impresses the monitoring input signal onto an output signal of the controller.

7. The monitoring method of claim 6, wherein the monitoring input signal is determined without influencing the output signal outputted by the controller, even though the monitoring input signal has triggered a movement of the drive device.

8. The monitoring method of claim 4, wherein the controller controls a position of the drive device.

9. The monitoring method of claim 4, wherein the controller controls a speed or rotation speed of the drive device.

10. The monitoring method of claim 4, wherein the drive device is constructed in the form of an electrical drive device, with the controller controlling a current flowing through the drive device.

12. The monitoring method of claim 1, wherein the monitoring device executes the monitoring method only when the drive device is not in motion.

13. The monitoring method of claim 1, wherein the monitoring device executes the monitoring method only when the drive device has not been moved over a time span which is greater than a wait time.

11. A method for monitoring an electrical drive device, which is activated by at least two current controllers operating phase-shifted with respect to one another, comprising the steps of:

providing a monitoring device to monitor at a standstill of the drive device an output signal of at least one of the current controllers for constancy; and

activating a safety device in the event of a change in the output signal of the at least one current controller, to transfer the drive device into a safe state.

14. A monitoring system for monitoring a drive device, comprising:

a monitoring device applying a monitoring input signal, which changes over time, to a drive device at a standstill; and

a sensor device operatively connected to the drive device and producing a sensor output signal which is modulated commensurate with the monitoring input signal in response to the monitoring input signal, when the sensor device functions properly,

wherein the monitoring device receives the sensor output signal,

wherein the monitoring device monitors the sensor output signal for the presence of a signal component which corresponds to the monitoring input signal, and

wherein the monitoring device activates a safety device to transfer the drive device into a safe state, when the monitoring device ascertains the absence of the signal component corresponding to the monitoring input signal.

15. A monitoring system for monitoring an electrical drive device, which is activated by at least two current controllers operating phase-shifted with respect to one another, comprising a monitoring device monitoring an output signal of at least one of the current controllers for constancy, when the drive device is at a standstill, wherein the monitoring device activates a safety device in the event of a change in the output signal of the at least one current controller, to transfer the drive device into a safe state.

16. A drive system for a movable element, comprising:

a drive device for moving the movable element;

a single sensor device for detecting one parameter of the drive device selected from the group consisting of actual position of the drive device, actual rotation speed of the drive device, and actual speed of the drive device;

a safety device for transferring the drive device into a safe state; and

a monitoring device applying a monitoring input signal, which changes over time, to the drive device at a standstill,

wherein the monitoring device receives a sensor output signal form the sensor device which is modulated commensurate with the monitoring input signal in response to the monitoring input signal, when the sensor device functions properly,

wherein the monitoring device monitors the sensor output signal for the presence of a signal component which corresponds to the monitoring input signal, and

wherein the monitoring device activates the safety device to transfer the drive device into the safe state, when the monitoring device ascertains the absence of the signal component corresponding to the monitoring input signal.

17. A drive system for a movable element, comprising:

an electrical drive device for moving the movable element, said drive device being activated by at least two current controllers operating phase-shifted with respect to one another;

a single sensor device for detecting one parameter of the drive device selected from the group consisting of actual position of the drive device, actual rotation speed of the drive device, and actual speed of the drive device;

a safety device for transferring the drive device into a safe state; and

a monitoring device monitoring an output signal of at least one of the current controllers for constancy, when the drive device is at a standstill, wherein the monitoring device activates the safety device in the event of a change in the output signal of the at least one current controller, to transfer the drive device into the safe state.