Control loop

Abstract

The invention relates to a control loop comprising a measured-value sensor (200), a control device (300) and an actuator (400), the actuator being connected to the measured-value sensor (200) via the industrial process (100). To detect faults in the control loop, it is proposed to impress on the wanted signal an interference signal having definable signal parameters, which is injected into the control loop by an interference-signal source (51 to 53). The interference-signal source has means for detecting and evaluating the interference signal fed back via the control loop in the direction of control action.

Description

The invention is described in greater detail below with reference to an exemplary embodiment and the necessary drawings which show:

The single FIGURE shows a block diagram of a control loop having a plurality of control-loop elements 10 to 43, which are grouped into physical units and assigned to an industrial process. The control-loop elements 21 to 23 are parts of a measured-value sensor 200. The control-loop elements 31 to 33 form a control device 300, and the control-loop elements 41 to 43 constitute an actuator 400. The industrial process 100 is represented as a single control-loop element 10 regardless of its complexity.

Claims

1. A control loop comprising in the direction of control action a measured-value sensor, a control device, an actuator and a control process, with the wanted signal circulating in the control loop in the direction of control action, wherein an interference signal having definable signal parameters is impressed on the wanted signal, said interference signal being injected into the control loop by an interference-signal source, andthe interference-signal source has means for detecting and evaluating the interference signal fed back via the control loop in the direction of control action.

2. The control loop as claimed in claim 1, wherein the interference-signal source is part of the measured-value sensor.

3. The control loop as claimed in claim 1, wherein the interference-signal source is part of the actuator.

4. The control loop as claimed in claim 1, wherein the interference-signal source is part of the control device.

5. The control loop as claimed in claim 1, wherein each interference signal is assigned an expected value of the change in wanted signal, where on the basis of the change in wanted signal that is actually detected compared with the expected value of the change in wanted signal, the difference can be signaled as an alert to a higher-level device.

6. The control loop as claimed in claim 5, wherein the interference signal is superimposed periodically on the wanted signal.

7. The control loop as claimed in claim 5, wherein the interference signal is superimposed on the wanted signal on the basis of a given event occurring.

8. The control loop as claimed in claim 2, wherein each interference signal is assigned an expected value of the change in wanted signal, where on the basis of the change in wanted signal that is actually detected compared with the expected value of the change in wanted signal, the difference can be signaled as an alert to a higher-level device.

9. The control loop as claimed in claim 3, wherein each interference signal is assigned an expected value of the change in wanted signal, where on the basis of the change in wanted signal that is actually detected compared with the expected value of the change in wanted signal, the difference can be signaled as an alert to a higher-level device.

10. The control loop as claimed in claim 4, wherein each interference signal is assigned an expected value of the change in wanted signal, where on the basis of the change in wanted signal that is actually detected compared with the expected value of the change in wanted signal, the difference can be signaled as an alert to a higher-level device.