Distributed control modules with built-in tests and control-preserving fault responses

1. A method of responding to faults in a control loop having a distributed control module, the method comprising:

determining a fault state associated with the control loop via a test module built into the distributed control module, the fault state comprising no faults, a communication fault, a sensor operation fault, or a critical fault; and

transmitting a control command from the distributed control module based on the fault state,

wherein when the fault state indicates no faults, the transmitting comprises transmitting a closed loop control command from the distributed control module to a controllable component,

wherein when the fault state indicates a communication fault or a sensor operation fault, the transmitting comprises transmitting an augmented control command from the distributed control module to the controllable component,

wherein when the fault state indicates a critical fault, the transmitting comprises transmitting a disconnect control command from the distributed control module to the controllable component.

2. The method of claim 1 , wherein the augmented control command comprises a closed-loop control command when the fault state comprises a communication fault.

3. The method of claim 1 , wherein the augmented control command comprises an open-loop control command when the fault state comprises a sensor operation fault.

4. The method of claim 1 , wherein the communication fault comprises a temporary communication fault, a local sensor fault, and or a main processing unit communication fault.

5. The method of claim 1 , wherein the critical fault comprises a processor fault, a memory fault, and/or a controllable component fault.

6. The method of claim 1 , comprising:

using a previous control command and/or a previous command reference in an augmented closed-loop control regime when the built-in test module determines a fault state comprising a temporary communication fault, the augmented closed-loop control regime including a control command module configured to transmit the augmented control command.

7. The method of claim 1 , comprising:

using a backup sensor channel in an augmented closed-loop control regime when the built-in test module determines a fault state comprising a local sensor fault, the augmented closed-loop control regime including a control command module configured to transmit the augmented control command.

8. The method of claim 1 , comprising:

using a pre-set command reference and/or a previous control command in an augmented closed-loop control regime when the built-in test module determines a fault state comprising a main processing unit communication fault, the augmented closed-loop control regime including a control command module configured to transmit the augmented control command.

9. The method of claim 1 , comprising:

using an open-loop control command in an open-loop control regime when the built-in test module determines a fault state comprising a sensor operation fault, the open-loop control regime including a control command module configured to transmit the open-loop control command, the augmented control command comprising the open-loop control command.

10. The method of claim 1 , comprising:

receiving sensor feedback from a sensor configured to measure a system variable of the controllable component.

11. The method of claim 1 , wherein the controllable component comprises an actuator or a servo-actuator.

12. The method of claim 11 , wherein the sensor comprises a position sensor configured to measure a position of the actuator or servo-actuator.

13. A distributed control system comprising:

a main processing unit, a distributed control module, and a controllable component, the distributed control module configured to:

determine a fault state associated with a control loop via a test module built into the distributed control module, the fault state comprising no faults, a communication fault, a sensor operation fault, or a critical fault; and

transmit a control command from the distributed control module based on the fault state,

wherein when the fault state indicates no faults, the control command comprises a closed-loop control command,

wherein when the fault state indicates a communication fault or a sensor operation fault, the control command comprises an augmented control command

wherein when the fault state indicates a critical fault, the control command comprises a disconnect control command.

14. The distributed control system of claim 13 , wherein the distributed control module comprises:

a built-in test module, the built-in test module configured to determine the fault state.

15. The distributed control system of claim 13 , wherein the controllable component comprises an actuator or servo-actuator coupled to a variable-geometry component.

16. The distributed control system of claim 15 , wherein the sensor comprises a position sensor configured to measure a position of the actuator or servo- actuator.

17. The distributed control system of claim 15 , wherein the variable-geometry component comprises a fuel valve, a variable-position fan blade, a variable-position guide vane, a variable-position compressor blade, or a variable-position turbine blade.

18. A non-transitory computer readable medium comprising computer-executable instructions, which, when executed by one or more processors of distributed control module, cause the distributed control module to:

determine a fault state associated with the control loop via a test module built into the distributed control module, the fault state comprising no faults, a communication fault, a sensor operation fault or a critical fault; and

transmit a control command from the distributed control module the fault state,

wherein when the fault state indicates no faults, the control command comprises a closed- loop control command,

wherein when the fault state indicates a communication fault or a sensor operation fault, the control command comprises an augmented control command

wherein when the fault state indicates a critical fault, the control command comprises a disconnect control command.

19. The non-transitory computer readable medium of claim 18 , wherein the computer readable medium is incorporated into or utilized with a full authority direct engine control (FADEC) system or an engine control unit (ECU) for a turbomachine and/or an aircraft.

20. A distributed control system comprising:

a distributed control module; and

a test module built into the distributed control module for enabling reconfiguration of only the control module,

wherein the distributed control module is configured to:

determine a fault state associated with a control loop via the test module, the fault state comprising no faults, a communication fault, a sensor operation fault, or a critical fault; and

transmit a control command from the distributed control module based on the fault state,

wherein when the fault state indicates no faults, the control command comprises a closed- loop control command,

wherein when the fault state indicates a communication fault or a sensor operation fault, the control command comprises an augmented control command,

wherein when the fault state indicates a critical fault, the control command comprises a disconnect control command.