PITCH AND THRUST CONTROL FOR TILT-ROTOR AIRCRAFT

• US 20190332125A1
• Filed: 05/22/2018
• Published: 10/31/2019
• Est. Priority Date: 04/25/2018
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Irwin, III, Joseph G., Miller, David G., Morgan, Nathaniel T.
• Granted Patent: US 10,935,985 B2
• Time in Patent Office: Days
• CPC Class Codes: B64C 13/506 overriding of personal controls; with automatic return to inoperative position
• CPC Class Codes: B64C 19/00 Aircraft control not otherwise provided for
• CPC Class Codes: B64C 2027/8227 comprising more than one rotor
• CPC Class Codes: B64C 2027/8236 including pusher propellers
• CPC Class Codes: B64C 27/10 arranged coaxially
• CPC Class Codes: B64C 27/22 Compound rotorcraft, i.e. aircraft using in flight the features of both aeroplane and rotorcraft
• CPC Class Codes: B64C 27/52 Tilting of rotor bodily relative to fuselage of see-saw type construction B64C27/43
• CPC Class Codes: B64C 27/56 characterised by the control initiating means, e.g. manually actuated
• CPC Class Codes: B64C 27/57 automatic or condition responsive, e.g. responsive to rotor speed, torque or thrust
• CPC Class Codes: B64C 29/0033 the propellers being tiltable relative to the fuselage
• CPC Class Codes: G05B 13/048 using a predictor
• CPC Class Codes: G05D 1/042 specially adapted for aircraft
• CPC Class Codes: G05D 1/0808 specially adapted for aircraft
• CPC Class Codes: G05D 1/0816 to ensure stability
• CPC Class Codes: G05D 1/085 to ensure coordination between different movements
• CPC Class Codes: G05D 1/0858 specially adapted for vertical take-off of aircraft

Abstract

A control circuitry includes a propulsor trim prediction circuitry and an output circuitry. The propulsor trim prediction circuitry is configured to generate a predicted proprotor nacelle trim value based on an aircraft velocity and a pitch attitude deviation from a reference. The output circuitry is configured to output a proprotor nacelle command based on the predicted proprotor nacelle trim value. The proprotor nacelle command is configured to cause an adjustment in a nacelle angle of a proprotor of an aircraft.

Claims

1. A control circuitry comprising:

a propulsor trim prediction circuitry configured to generate a predicted proprotor nacelle trim value for a target state of an aircraft based on an aircraft velocity and a pitch attitude deviation from a reference; and

an output circuitry configured to output a proprotor nacelle command based on the predicted proprotor nacelle trim value, the proprotor nacelle command configured to cause an adjustment in a nacelle angle of a proprotor of the aircraft.

2. The control circuitry of claim 1, wherein the predicted proprotor nacelle trim value indicates an estimated value of a pitch angle of a nacelle of the proprotor that produces a magnitude of thrust for an airspeed hold state or an acceleration hold state of the aircraft.

3. The control circuitry of claim 1, wherein the proprotor nacelle command is output to an actuator and is configured to cause the actuator to adjust a magnitude of proprotor thrust generated by adjusting a direction of the thrust in a pitch axis, and wherein the proprotor nacelle command is configured to cause the aircraft to operate in an airspeed hold state or an acceleration hold state of the aircraft.

4. The control circuitry of claim 1, wherein the propulsor trim prediction circuitry is configured to generate the predicted proprotor nacelle trim value further based on one or more pilot inputs.

5. The control circuitry of claim 1, further comprising a pitch attitude trim prediction circuitry configured to generate a predicted pitch attitude trim value for a target vertical state based on the aircraft velocity and a pitch attitude of the aircraft, wherein the pitch attitude deviation from the reference is generated based on the predicted pitch attitude trim value.

6. The control circuitry of claim 5, further comprising a regime recognition circuitry configured to:

generate a regime signal based on comparing the aircraft velocity to one or more thresholds; and

output the regime signal to one or more switches, wherein the regime signal indicates a mode of the aircraft, and wherein the proprotor nacelle command is generated based on the mode of the aircraft.

7. The control circuitry of claim 5, further comprising:

a pitch control inceptor configured to generate a pitch attitude input signal based on a pilot input; and

a pitch command model configured to generate an aircraft pitch attitude command based on the pitch attitude input signal and the predicted pitch attitude trim value, the aircraft pitch attitude command configured to cause the aircraft to operate in the target vertical state.

8. The control circuitry of claim 7, further comprising:

a pitch trim inceptor configured to generate a commanded pitch attitude trim value based on a second pilot input; and

a switch configured to output a predicted pitch attitude trim value or the commanded pitch attitude trim value as a selected pitch attitude trim value based on a regime signal, wherein the pitch attitude deviation from the reference is generated based on the selected pitch attitude trim value.

9. The control circuitry of claim 1, further comprising:

a thrust inceptor configured to generate a v-dot command signal;

a pitch control inceptor configured to generate a pitch attitude input signal;

a speed select mode circuitry configured to generate a speed select mode acceleration command based on the v-dot command signal;

an acceleration command mode circuitry configured to generate an acceleration command mode acceleration command based on the v-dot command signal and the pitch attitude input signal; and

a switch configured to output the speed select mode acceleration command or the acceleration command mode acceleration command as a selected acceleration command based on a regime signal, the proprotor nacelle command generated based on the selected acceleration command.

10. The control circuitry of claim 9, further comprising:

an acceleration controller configured to generate a delta proprotor nacelle value based on the selected acceleration command and the aircraft velocity; and

a combiner configured to generate a combined proprotor nacelle command based on the delta proprotor nacelle value and the predicted proprotor nacelle trim value, wherein the output circuitry comprises a propulsor limiting circuitry configured to limit the combined proprotor nacelle command to generate the proprotor nacelle command.

11. The control circuitry of claim 7, wherein the aircraft is a tilt-rotor aircraft, a high speed vertical takeoff and landing (VTOL) aircraft, or a combination thereof.

12. A method for controlling a tilt-rotor aircraft, the method comprising:

generating a predicted proprotor nacelle trim value for a target state of an aircraft based on an aircraft velocity and a pitch attitude deviation from a reference; and

adjusting a nacelle angle of a proprotor of the aircraft based on the predicted proprotor nacelle trim value.

13. The method of claim 12, further comprising generating the pitch attitude deviation from the reference based on an input pitch command and a selected pitch trim value.

14. The method of claim 12, further comprising:

generating a predicted pitch attitude trim value based on an aircraft velocity and a pitch attitude of the aircraft; and

adjusting an aircraft pitch attitude command based on a pitch attitude input signal and based on the predicted pitch attitude trim value or a commanded pitch attitude trim value.

15. The method of claim 14, further comprising, while operating in a high speed mode:

generating the aircraft pitch attitude command based on the predicted pitch attitude trim value; and

generating the predicted proprotor nacelle trim value based on the pitch attitude trim value.

16. The method of claim 15, further comprising, while operating in the high speed mode, generating a proprotor nacelle command based on a speed select mode acceleration command and the predicted proprotor nacelle trim value.

17. The method of claim 16, further comprising generating the speed select mode acceleration command, wherein generating the speed select mode acceleration command includes:

generating a pitch independent speed command based on a pitch independent acceleration command, wherein the pitch independent acceleration command is generated based on one or more pilot inputs;

generating a speed error signal based on subtracting the aircraft velocity from the pitch independent speed command; and

applying a gain to the speed error signal to generate the speed select mode acceleration command.

18. The method of claim 14, further comprising, while operating in a low speed mode:

generating the aircraft pitch attitude command based on the commanded pitch attitude trim value; and

generating the predicted proprotor nacelle trim value based on the commanded pitch attitude trim value.

19. The method of claim 18, further comprising, while operating in the low speed mode:

generating an acceleration command mode acceleration command based on the commanded pitch attitude trim value; and

generating a proprotor nacelle command based on the acceleration command mode acceleration command and the predicted proprotor nacelle trim value.

20. The method of claim 19, wherein generating the acceleration command mode acceleration command includes:

generating a pitch independent acceleration command by performing a table lookup based on a pilot input;

generating a gravity amplified longitudinal acceleration command by performing a table lookup based on a gravity compensated longitudinal acceleration; and

generating the acceleration command mode acceleration command based on the pitch independent acceleration command and the gravity amplified longitudinal acceleration command.