Arrangement and method for regulating the steering force in a mechanical steering system for an aircraft

• US 6,386,485 B1
• Filed: 05/22/2000
• Issued: 05/14/2002
• Est. Priority Date: 12/30/1997
• Status: Expired due to Fees

• Current Assignee: Saab AB
• Original Assignee: Saab AB
• Inventors: Sjöquist, Anders
• Primary Examiner(s): Barefoot, Galen L.
• Application Number:
  US09/554,886
• Time in Patent Office: 722 Days
• Field of Search: 244/76.R, 244/194, 244/195, 244/177, 244/178, 244/179, 701/4-9
• US Class Current: 244/194
• CPC Class Codes: B64C 13/50 using electrical energy

Abstract

The present invention relates to an arrangement and a method in a mechanical control system of an aircraft. From the cockpit of the aircraft control surfaces (1) of the aircraft can be acted upon via the control system by means of at least one control element (3), for example a wheel, a control column or a pair of pedals operatively connected to the control system. A servomotor (5) together with sensors is also connected to the control system. The sensors are designed, when acted upon by the control element (3), to detect the torque exerted on the control element (3) by a force applied thereto, the trim angle of the control element and the angular velocity with which the action occurs. The arrangement comprises a control device (9) which, on the basis of the conditions detected by the sensors, is designed to control the servomotor (5) so that a ratio between the force applied to the control element (3) and the trim angle of the control element assumes a desired, essentially constant value.

Claims

1. A system for mechanical control of an aircraft, the system comprising:

control surfaces operable to steer the aircraft;

at least one control element operable to act upon the control surfaces from a cockpit of the aircraft;

a servomotor operably connected to the at least one control element and first sensors, the servomotor and first sensors operable when acted upon by the at least one control element to detect a torque exerted on the at least one control element, a trim angle of the at least one control element, and an instantaneous angular velocity of the at least one control element; and

a control device operable to control the servomotor such that a ratio between a force applied to the at least one control element and the trim angle of the at least one control element is substantially constant.

2. The system according to claim 1, wherein the control surfaces comprise ailerons.

3. The system according to claim 1, wherein the at least one control element comprises a wheel, a control column, or a pair of pedals.

4. The system according to claim 1, further comprising:

an autopilot operably connected to and interacting with the servomotor.

5. The system according to claim 1, wherein the control surfaces comprise trimming tabs operable to trim roll and trimming jacks operable to act on the trimming tabs, the system further comprising:

second sensors operable to detect a position of the trimming jacks, wherein the at least one control device based upon positions detected by the second sensors is operable to define a trim position that the at least one control element has been made to assume as a median position for the at least one control element in an unaffected position where no gain is received from the servomotor.

6. The system according to claim 1, further comprising:

a filter operable to filter out local resonances on a basis of conditions detected by the first sensors.

7. The system according to claim 1, further comprising:

speed sensors for detecting a speed of the aircraft, wherein based upon the detected speed the system increases the ratio between the force applied to the control element and the trim angle of the control element as the speed of the aircraft increases and decreases the ratio between the force applied to the control element and the trim angle of the control element as the speed of the aircraft decreases.

8. A system for mechanically controlling an aircraft in which the aircraft comprises control surfaces operable to steer the aircraft and at least one control element operable to act upon the control surfaces from a cockpit of the aircraft, the system comprising:

a servomotor and sensors operably connected to the at least one control element and operable when acted upon by the at least one control element to detect a torque exerted on the at least one control element, to detect a trim angle of the at least one control element, and to detect an instantaneous angular velocity of the at least one control element; and

a control device operable to control the servomotor such that a ratio between a force applied to the at least one control element and the trim angle of the at least one control element is substantially constant.

9. A method for regulating a force applied to a control element of a mechanical system for controlling control surfaces of an aircraft to produce a desired trim angle, the method comprising:

detecting a force applied to a control element;

detecting a trim angle of the control element; and

based upon the detected conditions controlling a servomotor operably connected to the control element to achieve a desired substantially constant ratio between force applied to the control element and a trim angle of the control element.

10. The method according to claim 9, further comprising:

detecting an instantaneous velocity of the control element.

11. The method according to claim 9, wherein the force is applied to the control element through a torque applied to the control element.

12. The method according to claim 9, wherein the control element is operably connected to a mechanical control system and comprises a wheel, a control column, or a pair of petals.

13. The method according to claim 9, wherein the servomotor is operably connected to an autopilot system.

14. The method according to claim 9, wherein the control surfaces comprise trimming tabs operable to trim roll and trimming jacks operable to act on the trimming tabs, the method further comprising:

detecting a position of the trimming jacks; and

defining a median trim position for the control element in an unaffected state, wherein the median trim position is defined based upon a trim position that the control element is made to assume due to roll trimming, and wherein in the median trim position the servomotor does not amplify an input signal to the control system.

15. The method according to claim 9, further comprising:

filtering out local resonances in the mechanical control system.

16. The method according to claim 15, wherein the local resonances are filtered based upon the detected force and the detected trim angle.

17. The method according to claim 9, further comprising:

detecting a speed of the aircraft;

increasing the ratio between the force applied to the control element and the trim angle of the control element as the speed of the aircraft increases; and

decreasing the ratio between the force applied to the control element and the trim angle of the control element as the speed of the aircraft decreases.

18. The method according to claim 9, wherein the control surfaces comprise ailerons.