Dual channel signal selection and fault detection system
First Claim
1. An aircraft signal selection and fault detection system, comprising:
- a midvalue selector having an output and first, second, and third inputs, said first and second inputs being connected to receive first and second redundant localizer signals that are representative of the deviation of an aircraft from a runway centerline, said third input being connected to receive a third input signal that is representative of said deviation, said midvalue selector producing at its output the input signal corresponding to the midvalue of said input signals;
means for producing a synthesized rate signal that is representative of the rate of deviation of the aircraft from said runway centerline;
a normal mode complementary filter connected to receive said synthesized rate signal and the output of said midvalue selector, said filter being responsive to said signals to produce a normal mode complementary filter output signal that is representative of said deviation; and
means for coupling said normal mode complementary filter output signal as the third input signal to said midvalue selector.
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Accused Products
Abstract
A signal selection and fault detection system that provides triple functional redundancy using the outputs (YA, YB) of two unmonitored primary channels and the output of one or the other of two complementary filters (22, 34) that each receive and process a signal (Y dot IRU) that is derived from a third, independent primary signal source (18) and that is representative of the rate or first derivative of the primary signals (YA, YB). During non-failure conditions, the system output (YCF1) is generated by a normal mode complementary filter 22 from the synthesized rate signal (Y dot IRU) and the selected (10) midvalue one of this output signal (YCF1) and the primary signals (YA, YB). In the event of a suspected failure in one of the primary signals, the output (YIRU) of a failure mode complementary filter is substituted (16) for the system output signal (YCF1) as the third input (C) to the midvalue selector (10). The system includes a fault monitor (24) and a fault detector (26) to monitor the selected signal and generate switching signals (LOC FAIL, IC FILT, SELCHA, SELCHB) that control the switching between the normal mode and failure mode complementary filters and the isolation of the failed channels. Provisions (30, 32) are made for initializing integrators (52, 54) in the failure mode complementary filter and for varying the band width (C1, C2, A1, A2) of both the failure mode and the normal mode complementary filters as a function of a parameter that influences the primary signals.
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Citations
13 Claims
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1. An aircraft signal selection and fault detection system, comprising:
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a midvalue selector having an output and first, second, and third inputs, said first and second inputs being connected to receive first and second redundant localizer signals that are representative of the deviation of an aircraft from a runway centerline, said third input being connected to receive a third input signal that is representative of said deviation, said midvalue selector producing at its output the input signal corresponding to the midvalue of said input signals; means for producing a synthesized rate signal that is representative of the rate of deviation of the aircraft from said runway centerline; a normal mode complementary filter connected to receive said synthesized rate signal and the output of said midvalue selector, said filter being responsive to said signals to produce a normal mode complementary filter output signal that is representative of said deviation; and means for coupling said normal mode complementary filter output signal as the third input signal to said midvalue selector. - View Dependent Claims (2, 3)
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4. A signal and fault detection system, comprising:
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a midvalue sector having an output and first, second, and third inputs, said first and second inputs being connected to receive first and second redundant input signals, respectively, that correspond to a condition, said condition varying in accordance with a parameter, said third input being connected to receive a third input signal that is representative of said condition, said midvalue selector producing at its output the input signal corresponding to the midvalue of said input signals; means for producing a condition rate signal that is representative of the rate of change of said condition; a normal mode complementary filter connected to receive said condition rate signal and the output of said midvalue selector, said filter being responsive to said signals to produce a normal mode complementary filter output signal that is representative of said condition, said filter having a bandpass that varies in a predetermined manner as a function of said parameter; and means for coupling said normal mode complementary filter output signal as the third input signal to said midvalue selector.
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5. A signal selection and fault detection system, comprising:
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a midvalue selector having an output and first, second, and third inputs, said first and second inputs being connected to receive first and second redundant input signals, respectively, that correspond to a condition, said third input being connected to receive a third input signal that is representative of said condition, said midvalue selector producing at its output the input signal corresponding to the midvalue of said input signals; means for producing a condition rate signal that is representative of the rate of change of said condition; a normal mode complementary filter connected to receive said condition rate signal and the output of said midvalue selector, said filter being responsive to said signals to produce a normal mode complementary filter output signal that is representative of said condition; failure detection means for monitoring said redundant input signals and for providing a suspected failure signal when the difference between said redundant input signals exceeds a first predetermined threshold; a failure mode complementary filter connected to receive said condition rate signal, said filter producing a failure mode complementary filter output signal that is representative of said condition; and means for coupling said normal mode complementary filter output signal as the third input signal to said midvalue selector, said means for coupling including means responsive to said suspected failure signal for substituting said failure mode complementary filter output signal for said normal mode complementary filter output signal as the third input signal to said midvalue selector. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13)
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Specification