Flight control system

• US 8,725,321 B2
• Filed: 02/18/2010
• Issued: 05/13/2014
• Est. Priority Date: 05/17/2006
• Status: Active Grant

• Current Assignee: Textron Innovations Incorporated (Textron Inc)
• Original Assignee: Textron Innovations Incorporated (Textron Inc)
• Inventors: Hagerott, Steven G., Hammer, James L., Ciholas, Philippe A., Palmer, Mark W.
• Primary Examiner(s): Tran, Khoi
• Assistant Examiner(s): Nguyen, Bao Long T
• Application Number:
  US12/708,244
• Publication Number:
  US 20100145555A1
• Time in Patent Office: 1,545 Days
• Field of Search: None
• US Class Current: 701/10
• 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 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 positioning the powered control surfaces of an aircraft having both powered and unpowered control surfaces comprising the steps of:

measuring a force signal received from the pilot of the aircraft in response to the aerodynamic forces on the unpowered control surfaces;

converting the force signal into a torque signal;

applying a filter to the torque signal to calculate a control signal;

providing the control signal to the aircraft for positioning the powered control surfaces of the aircraft;

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;

calculating a control signal for the powered control surfaces from the angular position value;

subtracting the frictional torque value, the damping torque value, and the stiffness torque value from 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:

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;

calculating a control signal for the powered control surfaces from the angular position value;

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 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.

4. The process of claim 3 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.

5. The process of claim 3 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.

6. The process of claim 3 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.

7. The process of claim 3 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.

8. The process of claim 1 wherein the step of providing the control signal 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.

9. The process of claim 8 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.

10. The process of claim 8 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;

subtracting the adjusted position difference value from the torque signal.

11. The process of claim 1 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.