Methods and system for minor loop feedback fallback

Patent metadata

Field	Value
Publication number	US-12265384-B2
Application number	US-201514880806-A
Country	US
Kind code	B2
Filing date	Oct 12, 2015
Priority date	Jun 20, 2012
Publication date	Apr 1, 2025
Grant date	Apr 1, 2025

Abstract

Methods and system for minor loop feedback fallback are disclosed. An example method includes controlling a process control device using first values from a first sensor; comparing the first values to reference values to identify a difference; and in response to the difference being outside of a threshold, controlling the process control device using second values from a second sensor.

First claim

What is claimed is:

1. A non-transitory machine-readable medium comprising instructions which, when executed, cause a processor to at least:
determine a first minor loop feedback value based on a first control mode associated with a first minor loop feedback control path and a first sensor;
control a process control device at least partially based on the first minor loop feedback value;
identify (a) the first minor loop feedback value as outside a predetermined range of the first control mode or (b) a failure of the first control mode; and
in response to identifying that the first minor loop feedback value is outside of the predetermined range or the failure of the first control mode:
determine a second minor loop feedback value based on a second control mode associated with a second minor loop feedback control path and a second sensor; and
control the process control device at least partially based on the second minor loop feedback value, each of the first minor loop feedback value and the second minor loop feedback value to be determined upstream of an actuator of the process control device.

2. The machine-readable medium of claim 1 , wherein the instructions, when executed, further cause the processor to determine a position of a relay upstream of the process control device.

3. The machine-readable medium of claim 1 , wherein the instructions, when executed, further cause the processor to determine an output pressure of a relay upstream of the process control device.

4. The machine-readable medium of claim 3 , wherein the instructions, when executed, further cause the processor to determine a derivative of the output pressure to determine the second minor loop feedback value.

5. The machine-readable medium of claim 1 , wherein the instructions, when executed, further cause the processor to identify a failure of the second control mode and control the process control device at least partially based on a third minor loop feedback value of approximately zero and a reduced forward path value.

6. The machine-readable medium of claim 5 , wherein the reduced forward path value comprises a fixed upper limit or a fixed lower limit.

7. The machine-readable medium of claim 5 , wherein the reduced forward path value is approximately one third of a normal operation path value.

8. The machine-readable medium of claim 1 , wherein the instructions, when executed, further cause the processor to reduce a forward path value when the first minor loop feedback value is identified as being outside of the predetermined range or the failure of the first control mode is identified.

9. The machine-readable medium of claim 2 , wherein the instructions, when executed, cause the processor to determine the first minor loop feedback value based on the position of the relay.

10. The machine-readable medium of claim 3 , wherein the instructions, when executed, cause the processor to determine the first minor loop feedback value based on a derivative of the output pressure.

11. The machine-readable medium of claim 1 , wherein the first sensor is a minor loop feedback sensor and the second sensor is a pressure sensor.

12. The machine-readable medium of claim 11 , wherein the failure of the first control mode includes a failure of the minor loop feedback sensor.

13. The machine-readable medium of claim 11 , wherein the failure of the first control mode includes the first minor loop feedback value being constant.

14. The machine-readable medium of claim 1 , wherein, in response to identifying that the first minor loop feedback value is outside of the predetermined range or the failure of the first control mode, the instructions, when executed, cause a switch to move between the first control mode and the second control mode.

15. A non-transitory machine-readable medium comprising instructions which, when executed, cause a processor to at least:
determine a first minor loop feedback value based on a first sensor and a first control mode;
control a process control device at least partially based on the first minor loop feedback value;
identify (a) the first minor loop feedback value as outside a predetermined range of the first control mode or (b) a failure of the first control mode; and
in response to identifying that the first minor loop feedback value is outside of the predetermined range or the failure of the first control mode:
cause an alert to be output;
determine a second minor loop feedback value based on a second sensor and a second control mode; and
switch from controlling the process control device at least partially based on the first minor loop feedback value to controlling the process control device at least partially based on the second minor loop feedback value, each of the first minor loop feedback value and the second minor loop feedback value to be determined upstream of an actuator of the process control device.

16. An apparatus, comprising:
a housing; and
a processor disposed in the housing, the processor to:
determine a first minor loop feedback value based on a first control mode associated with a first minor loop feedback control path and a first sensor;
control a process control device at least partially based on the first minor loop feedback value;
identify (a) the first minor loop feedback value as outside a predetermined range or (b) a failure of the first control mode; and
in response to identifying that the first minor loop feedback value is outside of the predetermined range or the failure of the first control mode:
cause an alert to be output;
determine a second minor loop feedback value based on a second control mode associated with a second minor loop feedback control path and a second sensor; and
control the process control device at least partially based on the second minor loop feedback value, the first minor loop feedback control path upstream of the process control device and the second minor loop feedback control path upstream of an actuator of the process control device.

17. The apparatus of claim 16 , wherein the processor is to determine a position of a relay upstream of the process control device.

18. The apparatus of claim 16 , wherein the processor is to determine an output pressure of a relay upstream of the process control device.

19. The apparatus of claim 18 , wherein the processor is to determine a derivative of the output pressure to determine the second minor loop feedback value.

20. The apparatus of claim 16 , wherein the processor is to identify a failure of the second control mode and control the process control device at least partially based on a third minor loop feedback value of approximately zero and a reduced forward path value.

21. The apparatus of claim 20 , wherein the reduced forward path value comprises a fixed upper limit or a fixed lower limit.

22. The apparatus of claim 20 , wherein the reduced forward path value is approximately one third of a normal operation path value.

23. The apparatus of claim 16 , wherein the processor is to reduce a forward path value when the first minor loop feedback value is identified as being outside of the predetermined range or the failure of the first control mode is identified.

24. A method, comprising:
controlling a process control device using first values from a first sensor associated with a first minor loop feedback control path, the first values determined upstream of an actuator of the process control device;
comparing the first values

Assignees

• Fisher Controls Int Llc

Inventors

• Junk Kenneth

Classifications

• G05B9/03 Primary

  with multiple-channel loop, i.e. redundant control systems · CPC title