Control system utilizing fault detection
AssigneeHoneywell Inc.
InventorJohn K. Ho
Life of this patent
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Abstract
A control architecture having improved fault detection and correction capabilities is disclosed. The system comprises primary and monitor control systems, each having an associated control signal. A fault detector generates an alarm signal based upon differences observed between the primary and monitor control signal. The detector comprises an integrator and a memory means, and alarm signals are generated based upon the total amount of difference observed over a predetermined period of time. In one embodiment of the invention, primary and monitor control signals are averaged to provide a signal that is more fault tolerant than the individual control signals.
Claims23
An apparatus for controlling a plant comprising:
- a primary control system having a primary control signal;
- a monitor control system having a monitor control signal;
- a plurality of difference signals, each difference signal corresponding to the difference between said primary control signal and said monitor control signal at a fixed point in time;
- and
- a fault detector comprising:
- a filter transforming each of said difference signals into absolute difference values corresponding to the absolute difference between each of said difference signals and a magnitude threshold;
- a memory storing each of said absolute difference values for at least a pre-determined period of time;
- and
- an integrator in communication with said memory, said integrator maintaining a running accumulation of the absolute difference values observed during only the pre-determined period of time.
A method of detecting faults in a control system, the method comprising the steps of:
- determining differences between a primary control signal and a monitor control signal at regular time intervals;
- determining absolute differences between the differences and a threshold value;
- adding said absolute differences to a total absolute difference signal;
- retaining each of said absolute differences in a memory for at least a pre-determined period of time;
- subtracting each of said absolute differences from said total absolute difference signal after said predetermined period of time has expired;
- and
- providing an alarm signal when said total absolute difference signal exceeds a maximum allowable difference value.
A method of controlling a plant comprising the steps of:
- providing a primary control signal (P) and a monitor control signal (M);
- averaging the primary control signal and the monitor control signal to produce an average control signal that is provided to the plant;
- subtracting said average control signal from said primary control signal to obtain a resultant signal substantially equal to (P-M)/2;
- and
- multiplying said resultant signal by two to obtain an error signal substantially equal to P-M.
An apparatus for controlling a plant comprising:
- a primary control system having a primary control signal;
- a monitor control system having a monitor control signal;
- a plurality of difference signals, each difference signal being related to the difference between the primary control signal and the monitor control signal at a fixed point in time;
- and
- a fault detector having an integrator, the integrator maintaining a representation of the total of the difference signals observed over only a pre-determined interval, the fault detector providing an error signal to the plant when the total of the difference signals exceeds a threshold value.
Dependencies are inferred from the claim text.