Automatic conversion system for tiltrotor aircraft

• US 20090114764A1
• Filed: 09/22/2006
• Published: 05/07/2009
• Est. Priority Date: 09/22/2006
• Status: Active Grant

• Current Assignee: Bell Helicopter Textron Incorporated (Textron Inc)
• Original Assignee: Bell Helicopter Textron Incorporated (Textron Inc)
• Inventors: Gore, Billy K., Schulte, Kynn J., Builta, Kenneth E., Harris, James E.
• Granted Patent: US 7,571,879 B2
• Time in Patent Office: Days
• US Class Current: 244/17.130
• CPC Class Codes: B64C 29/0033 the propellers being tiltable relative to the fuselage
• CPC Class Codes: G05D 1/0858 specially adapted for vertical take-off of aircraft

Abstract

One embodiment of the present invention is a method for automatically controlling the conversion of a tiltrotor aircraft. An airspeed command for the tiltrotor aircraft is received. The airspeed command is converted to a pylon position. A difference between the airspeed command and a measured airspeed is calculated. The difference between the airspeed command and a measured airspeed is converted to a dynamic pylon position. A total pylon position is calculated from the pylon position and the dynamic pylon position. A pylon of the tiltrotor aircraft is moved to the total pylon position. Another embodiment of the present invention is a system for calculating a position of a pylon of a tiltrotor aircraft based on an airspeed command. The system includes an airspeed command module, a pylon trim position module, a dynamic pylon position module, and a pylon position module.

Claims

1. A method for automatically controlling the conversion of a tiltrotor aircraft, comprising:

receiving an airspeed command for the tiltrotor aircraft;

converting the airspeed command to a pylon position;

calculating a difference between the airspeed command and a measured airspeed;

converting the difference to a dynamic pylon position;

calculating a total pylon position from the pylon position and the dynamic pylon position; and

moving a pylon of the tiltrotor aircraft to the total pylon position.

2. The method of claim 1, wherein the receiving the airspeed command step comprises receiving control stick input from a pilot and converting it to the airspeed command.

3. The method of claim 1, wherein the receiving the airspeed command step comprises one of receiving control stick input from an operator of a flight control box and converting it to the airspeed command, receiving the airspeed command step comprises one of receiving a command from an operator of a ground control station and converting it to the airspeed command, and receiving a command from a pre-programmed automated maneuver.

4. The method of claim 3, wherein the automated maneuver comprises an algorithm stored on a flight control computer, wherein the algorithm comprises one of a circle mode, a return mode, a stall recovery, and a navigational mode.

5. The method of claim 1, wherein the converting the airspeed command to the pylon position step comprises searching a lookup table for the pylon position corresponding to the airspeed command.

6. The method of claim 5, wherein if the tiltrotor aircraft is decelerating, the converting the airspeed command to the pylon position step comprises searching a deceleration lookup table for a deceleration pylon position corresponding to the airspeed command and calculating a difference between the pylon position and the deceleration pylon position to produce the pylon position.

7. The method of claim 1, further comprising controlling a flap position of the tiltrotor aircraft as a function of the total pylon position and the airspeed command.

8. The method of claim 7, wherein the controlling the flap position step comprises

searching a flap lookup table as a function of total pylon for a pylon flap position corresponding to the total pylon position,

searching an flap lookup table that is a function of airspeed command for an airspeed flap position corresponding to the airspeed command, and

adding the pylon flap position and the airspeed flap position to produce the flap position.

9. A method for calculating a position of a pylon of a tiltrotor aircraft based on an airspeed command, comprising:

receiving an airspeed command signal for the tiltrotor aircraft;

converting the airspeed command signal to the airspeed command;

converting the airspeed command to a pylon trim position;

calculating an airspeed error from a difference between the airspeed command and a measured airspeed;

converting the airspeed error to a dynamic pylon position; and

calculating the position of the pylon from the pylon trim position and the dynamic pylon position.

10. The method of claim 9, wherein the airspeed command signal is one of a control stick input from a pilot, a control stick input from an operator of a flight control box, a command from an operator of a ground control station, and a command from a pre-programmed automated maneuver.

11. The method of claim 9, wherein the converting the airspeed command signal to the airspeed command step comprises:

if the airspeed command signal comprises a control stick input, selecting a signal level and integrating the signal level to produce the airspeed command,

if the airspeed command signal comprises a command, calculating a difference between the command and a previous airspeed command, limiting the amplitude of the difference and integrating the difference to produce the airspeed command, and

if the airspeed command signal comprises a pre-programmed maneuver, executing an algorithm describing the pre-programmed maneuver on a flight control computer to produce the airspeed command.

12. The method of claim 9, wherein the converting the airspeed command to the pylon trim position step comprises:

if the tiltrotor is accelerating, searching a lookup table for a lookup table pylon trim position corresponding to the airspeed command and rate limiting the lookup table pylon trim position to produce the pylon trim position, and

if the tiltrotor is decelerating, searching a lookup table for a lookup table pylon trim position corresponding to the airspeed command, searching a deceleration lookup table for a deceleration lookup table pylon trim position corresponding to the airspeed command, calculating a difference between the lookup table pylon trim position and the deceleration lookup table pylon trim position, and rate limiting the difference to produce the pylon trim position.

13. The method of claim 9, wherein the converting the airspeed error to the dynamic pylon position step comprises:

computing the airspeed error by taking a difference between the airspeed command and the airspeed feedback,

adjusting the airspeed error to create a proportional command,

adjusting the airspeed error and integrating the airspeed error to create an integral command, and

summing the proportional command and the integral command to produce the dynamic pylon position.

14. The method of claim 9, wherein the calculating the position of the pylon from the pylon trim position and the dynamic pylon position step comprises:

calculating the position of the pylon from a difference between the pylon trim position and the dynamic pylon position.

15. A system for calculating a position of a pylon of a tiltrotor aircraft based on an airspeed command, comprising:

an airspeed command module that receives an airspeed command signal for the tiltrotor aircraft and converts the airspeed command signal to the airspeed command;

a pylon trim position module that receives the airspeed command from the airspeed command module and converts the airspeed command to a pylon trim position;

a dynamic pylon position module that receives the airspeed command from the airspeed command, calculates an airspeed error from a difference between the airspeed command and a measured airspeed, and converts the airspeed error to a dynamic pylon position; and

a pylon position module that receives pylon trim position from the pylon trim position module and the dynamic pylon position from the dynamic pylon position module and calculates the position of the pylon from the pylon trim position and the dynamic pylon position.

16. The system of claim 15, wherein the airspeed command signal is one of a control stick input from a pilot, a control stick input from an operator of a flight control box, a command from an operator of a ground control station, and a command from a pre-programmed automated maneuver.

17. The system of claim 15, wherein

if the airspeed command signal comprises a control stick input, the airspeed command module converts the control stick input to the airspeed command by adjusting the level of the control stick input to produce an adjusted signal and integrating the adjusted signal to produce the airspeed command,

if the airspeed command signal comprises a command, the airspeed command module converts the command to the airspeed command by calculating a difference between the command and a previous airspeed command, limiting the amplitude of the difference, and integrating the difference to produce the airspeed command, and

if the airspeed command signal comprises a pre-programmed maneuver, the airspeed command module converts the command to the airspeed command by executing an algorithm describing the pre-programmed maneuver on a flight control computer to produce the airspeed command.

18. The system of claim 15, wherein

if the tiltrotor is accelerating, the pylon trim position module converts the airspeed command to the pylon trim position by searching a lookup table for a lookup table pylon trim position corresponding to the airspeed command and rate limiting the lookup table pylon trim position to produce the pylon trim position, and

if the tiltrotor is decelerating, the pylon trim position module converts the airspeed command to the pylon trim position by searching a lookup table for a lookup table pylon trim position corresponding to the airspeed command, searching a deceleration lookup table for a deceleration lookup table pylon trim position corresponding to the airspeed command, calculating a difference between the lookup table pylon trim position and the deceleration lookup table pylon trim position, and rate limiting the difference to produce the pylon trim position.

19. The system of claim 15, wherein the dynamic pylon position module converts the airspeed error to the dynamic pylon position by

computing the airspeed error by taking a difference between the airspeed command and the airspeed feedback,

adjusting the airspeed error to create a proportional command,

adjusting the airspeed error and integrating the airspeed error to create an integral command, and

summing the proportional command and the integral command to produce the dynamic pylon position.

20. The system of claim 15, wherein the pylon position module calculates the position of the pylon from the pylon trim position and the dynamic pylon position by calculating the position of the pylon from a difference between the pylon trim position and the dynamic pylon position.