Autopilot/flight director underspeed protection system
First Claim
1. A method of limiting underspeed in an aircraft having flaps, comprising the steps of:
- selecting a set of flight parameters;
determining a target speed of the aircraft;
determining an actual speed of the aircraft;
comparing the target speed to the actual speed;
producing an electrical first error signal indicative of the difference between the actual speed and the target speed;
monitoring a flap position of the flaps;
adjusting the first error signal in response to the monitored flap position;
receiving the adjusted first error signal with an electronic controller; and
adjusting the selected set of flight parameters with the electronic controller in response to the adjusted first error signal.
1 Assignment
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Accused Products
Abstract
An underspeed protection system for an aircraft under autopilot control selects a target speed based upon the greater of a minimum maneuver speed and a stick shaker speed. The system then compares a monitored speed to the target speed to produce an error signal. The system also monitors vertical speed to determine if the aircraft begins to descend. If the error signal due to the underspeed condition causes the aircraft to descend, the system provides a hold zero vertical speed signal in place of the error signal such that the aircraft seeks to maintain its altitude. The hold zero vertical speed signal overrides the underspeed error signal such that the aircraft does not pitch forward to seek an increased speed.
44 Citations
17 Claims
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1. A method of limiting underspeed in an aircraft having flaps, comprising the steps of:
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selecting a set of flight parameters; determining a target speed of the aircraft; determining an actual speed of the aircraft; comparing the target speed to the actual speed; producing an electrical first error signal indicative of the difference between the actual speed and the target speed; monitoring a flap position of the flaps; adjusting the first error signal in response to the monitored flap position; receiving the adjusted first error signal with an electronic controller; and adjusting the selected set of flight parameters with the electronic controller in response to the adjusted first error signal. - View Dependent Claims (14, 17)
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2. A method for limiting underspeed in an aircraft under autopilot control, the autopilot establishing a set of flight control parameters to seek a selected flight condition of the aircraft, comprising the steps of:
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selecting a nominal minimum maneuver speed for the aircraft; selecting a target speed relative to the minimum maneuver speed; determining an actual speed of the aircraft; comparing the actual speed to the target speed; if the determined actual speed of the aircraft is below the target speed, producing a first underspeed signal; supplying the first underspeed signal to an electronic flight controller; in response to the first underspeed signal, overriding the set of flight control parameters with the flight controller by supplying a revised set of flight control parameters to seek a revised flight condition in which the actual speed of the aircraft approaches the target speed; and after overriding the set of flight control parameters, maintaining the revised set of flight control parameters until either the autopilot is disengaged or a new set of flight control parameters is selected by a pilot. - View Dependent Claims (15, 16)
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3. A method for limiting underspeed in an aircraft under autopilot control, the autopilot establishing a set of flight control parameters to seek a selected flight condition of the aircraft, comprising the steps of:
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selecting a nominal minimum maneuver speed for the aircraft; selecting a target speed relative to the minimum maneuver speed; determining an actual speed of the aircraft; comparing the actual speed to the target speed; if the determined actual speed of the aircraft is below the target speed, producing a first underspeed signal; supplying the first underspeed signal to an electronic flight controller; and in response to the first underspeed signal, overriding the set of flight control parameters with the flight controller by supplying a revised set of flight control parameters to seek a revised flight condition in which the actual speed of the aircraft approaches the target speed; and wherein the step of selecting a minimum maneuver speed includes the steps of; selecting a stick shaker speed for a monitored flight condition; selecting a safety margin; and adding the safety margin to the stick shaker speed to determine a stick shaker-based minimum speed. - View Dependent Claims (4)
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5. A method for limiting underspeed in an aircraft under autopilot control, the autopilot establishing a set of flight control parameters to seek a selected flight condition of the aircraft, comprising the steps of:
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selecting a nominal minimum maneuver speed for the aircraft; selecting a target speed relative to the minimum maneuver speed; determining an actual speed of the aircraft; comparing the actual speed to the target speed; if the determined actual speed of the aircraft is below the target speed, producing a first underspeed signal; supplying the first underspeed signal to an electronic flight controller; and in response to the first underspeed signal, overriding the set of flight control parameters with the flight controller by supplying a revised set of flight control parameters to seek a revised flight condition in which the actual speed of the aircraft approaches the target speed, wherein the step of selecting a target speed relative to the minimum maneuver speed includes the step of adding a speed margin to the minimum maneuver speed, and wherein the step of producing a first underspeed signal includes the step of producing a signal proportional to the difference between the actual speed and the target speed. - View Dependent Claims (6)
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7. A method for controlling descent in an aircraft under autopilot control, the autopilot establishing a set of flight control parameters to seek a selected flight condition of the aircraft, comprising the steps of:
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selecting a nominal minimum maneuver speed for the aircraft; selecting a target speed relative to the minimum maneuver speed; monitoring an actual speed of the aircraft; establishing a hold zero vertical speed set of flight parameters; comparing the actual speed to the target speed; if the actual speed of the aircraft is below the target speed, producing a first underspeed signal; supplying the first underspeed signal to an electronic flight controller; in response to the first underspeed signal, determining a revised set of flight control parameters; determining a response of the aircraft to the revised set of flight control parameters; if the revised set of flight control parameters causes the aircraft to descend, overriding the set of flight control parameters with the flight controller by supplying to the hold zero vertical speed set of flight control parameters to the autopilot; and if the revised set of flight control parameters does not cause the aircraft to descend, overriding the set of flight control parameters with the flight controller by supplying to the revised set of flight control parameters to the autopilot. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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Specification