Flight Control System

• US 20100145555A1
• Filed: 02/18/2010
• Published: 06/10/2010
• Est. Priority Date: 05/17/2006
• Status: Active Grant

• Current Assignee: Textron Innovations Incorporated (Textron Inc)
• Original Assignee: Cessna Aircraft Company (Textron Inc)
• Inventors: Hagerott, Steven G., Ciholas, Philippe A., Palmer, Mark W., Hammer, James L.
• Granted Patent: US 8,725,321 B2
• Time in Patent Office: Days
• US Class Current: 701/3
• CPC Class Codes: B64C 13/507 with artificial feel
• CPC Class Codes: B64C 9/04 with compound dependent movements
• CPC Class Codes: B64C 9/10 one surface adjusted by movement of another, e.g. servo tabs B64C9/04 takes precedence; adjusting surfaces of different type or function B64C9/12

Abstract

A system and method for a controlling an aircraft with flight control surfaces that are controlled both manually and by a computing device is disclosed. The present invention improves overall flight control operation by reducing the mechanical flight control surface components while providing sufficient back-up control capability in the event of either a mechanical or power-related failure. Through the present invention, natural feedback is provided to the operator from the mechanical flight control surface which operates independent of computer-aided flight control surfaces. Further, through the present invention, force input signals received from the pilot are filtered to improve the operation of the computer-aided flight control surfaces.

Claims

1. A process for filtering a force signal received from the pilot of an aircraft having both powered and unpowered control surfaces comprising the steps of:

converting the force signal into a torque signal;

applying a filter to the torque signal.

2. The process of claim 1 wherein the step of applying a filter to the torque signal further comprises the steps of:

converting the torque signal into an angular acceleration value;

converting the angular acceleration value into an angular velocity value;

calculating a frictional torque value for the angular velocity;

calculating a damping torque value for the angular velocity;

converting the angular velocity value into an angular position value;

calculating a stiffness torque for the angular position value;

providing a control signal for the powered control surfaces calculated from the angular position value to the aircraft;

subtracting the frictional torque value, the damping torque value, and the stiffness torque value from the torque signal.

3. The process of claim 1 wherein the step of applying a filter to the torque signal further comprises the steps of:

calculating a frictional torque value for the torque signal;

converting the torque signal into an angular acceleration value;

converting the angular acceleration value into an angular velocity value;

calculating a damping torque value for the angular velocity;

converting the angular velocity value into an angular position value;

calculating a stiffness torque for the angular position value;

providing a control signal for the powered control surfaces calculated from the angular position value to the aircraft;

subtracting the frictional torque value, the damping torque value, and the stiffness torque value from the torque signal.

4. The process of claim 2 wherein the step of converting the torque signal into an angular acceleration value comprises integrating the torque signal over a period of time and the step of converting the angular acceleration value into an angular velocity value comprises integrating the angular acceleration value over a period of time.

5. The process of claim 4 wherein the step of calculating a frictional torque value for the angular velocity value comprises applying a frictional deadband model to the angular velocity value.

6. The process of claim 5 wherein the step of calculating a damping torque value for the angular velocity value comprises multiplying the angular velocity value by a damping coefficient value selected from a schedule of values measured in wind tunnel and test flights.

7. The process of claim 6 wherein the step of converting the angular velocity value into an angular position value comprises integrating the angular velocity value over a period of time.

8. The process of claim 7 wherein the step of calculating a stiffness torque for the angular position value further comprises selecting a hinge moment as a function of the angular position value from a schedule of values measured in wind tunnel and test flights.

9. The process of claim 8 wherein the step of providing a control signal calculated from the angular position value to the aircraft further comprises the steps of:

applying a gain factor to the angular position value to calculate a powered surface angular position estimated value;

applying a lag compensator to the powered surface angular position estimated value to calculate a control signal.

10. The process of claim 9 wherein the step of calculating a stiffness torque for the angular position value further comprises the step of selecting a hinge moment as a function of the angular position value and of the powered surface angular position estimated value from a schedule of values measured in wind tunnel and test flights.

11. The process of claim 10 further comprising the steps of:

measuring the actual angular position of the unpowered control surfaces;

subtracting the angular position value from the actual angular position to calculate a position difference value;

multiplying the position difference value by a time constant to produce an adjusted position difference value;

adjusting the adjusted torque value by the adjusted position difference value.

12. The process of claim 11 wherein the aircraft has a control means for inputting a force signal, and the step of converting the force signal into a torque value comprises multiplying the force signal by the moment of inertia of the control means.

13. A process for modifying a control signal received from a pilot of an aircraft having unpowered and powered control systems comprising the steps of:

modifying the control signal to compensate for the characteristics of the unpowered control systems; and

providing the control signal to the powered control system.

14. The process of claim 13 wherein the step of modifying the control signal further comprises the steps of:

modifying the control signal to compensate for the inertia of the unpowered control system;

modifying the control signal to compensate for friction of the unpowered control system;

modifying the control signal to compensate for damping of the unpowered control system;

modifying the control signal to compensate for stiffness of the unpowered control system.

15. The process of claim 14 wherein the control signal represents the force applied by the pilot to a control device for the aircraft.

16. The process of claim 15 wherein the characteristics of the unpowered control systems are measured in flight and wind tunnel testing.

17. A process for manipulating a command signal for an aircraft comprising the steps of:

receiving a control signal from a pilot of the aircraft;

modifying the control signal to compensate for the physical characteristics of the aircraft;

providing the control signal to a control system of the aircraft.

18. The process of claim 17 wherein the control system comprises powered control systems and unpowered control systems, and wherein the control signal is provided to the powered control system.

19. The process of claim 18 wherein the physical characteristics comprise inertia, damping, friction and stiffness.

20. The process of claim 19 wherein the step of modifying the control signal further comprises modeling the physical characteristics of the unpowered control system.