Autopilot hardover failure protection system
First Claim
1. An autopilot failure protection system for an aircraft, comprising:
- first signal processing means responsive to a signal indicative of the actual pitch attitude of the aircraft and for producing thereform a pitch rate signal and a warning signal;
nuisance disconnect inhibiting means for receiving the pitch rate signal and an aircraft elevator signal and for producing an inhibit signal; and
first summing means for receiving the warning signal and the inhibit signal, for producing a disengagement signal which represents the combination of the warning signal and of the inhibit signal, and for providing the disengagement signal to an aircraft autopilot.
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Accused Products
Abstract
A system for rapidly disengaging, with minimum nuisance disengagements, a nventional autopilot system upon detecting hardover failure, which is defined as any autopilot failure which results in rapid and sustained displacement of an aircraft aerodynamic control surface. The aircraft pitch rate is measured and compared with established limits. If these limits are exceeded, the system causes automatic disengagement. Disengagement is inhibited for gust disturbances by deriving a nose up or down signal from the pitch rate signal which is then compared with a signal indicating the direction of elevator hinge moment; if the two directions are opposing, disengagement is inhibited. Disengagement is also inhibited in the event of pilot action. Also, the autopilot pitch axis command line is monitored and a disengagement overriding any inhibits is generated when the signal on that line exceeds certain limits for the altitude hold mode and for the attitude hold mode of the autopilot.
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Citations
48 Claims
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1. An autopilot failure protection system for an aircraft, comprising:
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first signal processing means responsive to a signal indicative of the actual pitch attitude of the aircraft and for producing thereform a pitch rate signal and a warning signal; nuisance disconnect inhibiting means for receiving the pitch rate signal and an aircraft elevator signal and for producing an inhibit signal; and first summing means for receiving the warning signal and the inhibit signal, for producing a disengagement signal which represents the combination of the warning signal and of the inhibit signal, and for providing the disengagement signal to an aircraft autopilot. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. An autopilot failure protection system for an aircraft, comprising:
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signal processing means for receiving an aircraft pitch attitude signal and for producing a pitch rate signal; and a first window compartor for receiving the pitch rate signal, for comparing the pitch rate signal with a predetermined reference value, for producing a disengagement signal whose value indicates whether the pitch rate signal exceeds the predetermined reference value, and for providing the disengagement signal to an aircraft autopilot.
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23. An autopilot failure protection system for an aircraft, comprising:
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signal processing means for receiving an aircraft pitch attitude signal and for producing a pitch rate signal; first comparing means for receiving the pitch rate signal, for comparing the pitch rate signal with a predetermined reference value, for producing a disengagement signal whose value indicates whether the pitch rate signal exceeds the predetermined reference value, and for providing the disengagement signal to an aircraft autopilot; and time delay means receiving the disengagement signal for applying a predetermined time delay thereto.
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24. An autopilot failure protection system for an aircraft, comprising:
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first demodulating means for receiving an aircraft pitch attitude signal and for producing a demodulated pitch attitude signal; second demodulating means for receiving and demodulating an aircraft pitch wheel signal and for producing a demodulated pitch wheel signal; compensating filter means for receiving the demodulated pitch wheel signal and producing a filtered demodulated pitch wheel signal whose phase corresponds to the phase of the pitch attitude signal; first summing means operatively interposed between said first demodulating means and said signal processing means for receiving the demodulated pitch attitude signal and the filtered demodulated pitch wheel signal, and for producing a corrected pitch attitude signal which represents the difference between demodulated pitch attitude signal and the filtered demodulated pitch wheel signal; signal processing means for receiving said corrected pitch attitude signal and for producing a pitch rate signal; and first comparing means for receiving the pitch rate signal, for comparing the pitch rate signal with a predetermined reference value, for producing a disengagement signal whose value indicates whether the pitch rate signal exceeds the predetermined reference value, and for providing the disengagement signal to an aircraft autopilot. - View Dependent Claims (25)
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26. An autopilot failure protection system for an aircraft, comprising:
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compensating filter means for receiving an aircraft pitch wheel signal and producing a filtered pitch wheel signal whose phase corresponds to the phase of an aircraft pitch attitude signal; first summing means receiving the pitch attitude signal and the filtered pitch wheel signal, for producing a corrected pitch attitude signal which represents the difference between the pitch attitude signal and the filtered pitch wheel signal; signal processing means for receivng the corrected pitch attitude signal and for producing a pitch rate signal; and first comparing means for receivng the pitch rate signal, for comparing the pitch rate signal with a predetermined reference value, for producing a disengagement signal whose value indicates whether the pitch rate signal exceeds the predetermined reference value, and for providing the disengagement signal to an aircraft autopilot. - View Dependent Claims (27)
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28. An autopilot failure protection system for an aircraft comprising:
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signal processing means for receiving an aircraft pitch attitude signal and for producing a pitch rate signal; first comparing means for receiving the pitch rate signal, for comparing the pitch rate signal with a predetermined reference value, and for producing a disengagement signal whose value indicates whether the pitch rate signal exceeds the predetermined reference value; second comprising means for receiving an aircraft pitch axis command signal, for comparing the command signal with an externally determined referenced value, and for producing an override signal whose value indicates whether the command signal exceeds the externally determined reference value; switching means for receiving an autopilot altitude hold signal for providing one of two predetermined reference signals selected according to the state of the hold signal, as the externally determined reference value, to said second comprising means; and second summing means for receiving the disengagement signal and the override signal, for producing a disconnect signal representing the combination of the disengagement signal and the override signal, and for providing the disconnect signal to the autopilot. - View Dependent Claims (29, 30, 31)
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32. An autopilot nuisance disconnect inhibit system comprising:
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first signal processing means for receiving an aircraft pitch rate signal and for producing a bipoloar signal indicating the direction of any aircraft pitch attitude excursion; second signal processing means for receiving an aircraft elevator signal for producing a direction signal whose polarity indicates the direction of elevator loading; first summing means for receiving the bipolar signal and the direction signal and for producing a combination signal which represents the combination of the bipolar signal and of the direction signal; and absolute value generating means for receiving the combination signal, for producing an inhibit signal which is the absolute value of the combination signal and for providing the inhibit signal to the autopilot. - View Dependent Claims (33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44)
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45. An autopilot failure protection system for an aircraft, comprising:
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comparing means for receiving an aircraft pitch axis command signal, for comparing the command signal with an externally determined reference value, for producing an override signal whose value indicates whether the command signal exceeds the externally determined reference value, and for providing said override signal to the autopilot; and switching means for receiving an autopilot altitude hold signal for providing one of two predetermined reference signals, selected according to the state of the hold signal, and the externally determined reference value to said comparing means. - View Dependent Claims (46, 48)
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47. An autopilot failure protection system as defined in claim 49 further comprising:
amplifier means for amplifying the override signal.
Specification