Method and apparatus for stabilizing the steering force in an aircraft, especially a helicopter

• US 4,664,346 A
• Filed: 05/06/1985
• Issued: 05/12/1987
• Est. Priority Date: 05/08/1984
• Status: Expired due to Fees

• Current Assignee: Eurocopter Deutschland Gesellschaft Mit Beschrã¤Nkter Haftung (European Aeronautic Defence and Space Company EADS NV)
• Original Assignee: Messerschmitt-Boelkow-Blohm GmbH (Mercedes-Benz Group AG)
• Inventors: Koenig, Herbert
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Fiorito, Lynn M.
• Application Number:
  US06/730,546
• Time in Patent Office: 736 Days
• Field of Search: 244/223, 244/17.13, 244/178, 244/221, 318/628
• US Class Current: 244/223
• CPC Class Codes: B64C 13/46 with artificial feel
• CPC Class Codes: G05D 1/0061 for transition from automatic pilot to manual pilot and vice versa
• CPC Class Codes: G05D 1/0858 specially adapted for vertical take-off of aircraft

Abstract

The steering or control force for operating a steering column in an aircraft, especially in a rotary wing aircraft, is stabilized. The steering column influences through an articulated steering or control linkage the elevator assembly or the rotor blade adjustment, whereby a signal is employed which is dependent on the measured flight speed. It is necessary to signal to the pilot at all times how the steering column must be moved. Such signalling must be definite and free of any disturbing influences and the pilot must receive such signalling through the steering column manual force which is a force reacting to the operation of the steering column. For this purpose a speed dependent signal is supplied to a servomotor. This signal rises with the flight speed at least above a preselectable threshold value. The servomotor in turn controls the tensioning state of a spring which is pivoted at one end to the steering column and at the other end to the displacement member of the servomotor. Preferably, the point of articulation between the spring and the steering column is located approximately opposite the point of articulation between the steering column and the steering or control linkage. Additionally, a feedback signal derived from sensing the displacement caused by the servomotor is added to the speed dependent signal. The feedback signal varies in the same sense as the displacement caused by the servomotor and serves to achieve proportionality between the signal S and said displacement.

Claims

1. A method for stabilizing the steering force in an aircraft, wherein a steering column is connected in an articulated manner through a steering linkage to controlled means, comprising the following steps:

(a) measuring the flight speed and producing a flight speed signal which is speed dependent at least above a certain speed threshold value,

(b) measuring a displacement caused by a servomotor pivoted through a spring to said steering column at a point located approximately opposite a point at which said steering linkage is articulated or pivoted to said steering column, and producing a displacement responsive feedback signal, and

(c) supplying said speed dependent signal and said feedback signal through signal combining means to said servomotor for controlling the tension state of said spring by any displacement caused by said servomotor in response to said speed dependent signal as modified by said feedback signal for imparting to said steering column through the instantaneous tension state of said spring a reaction force which signals to the pilot the correct movement direction to be imparted to the steering column.

2. The method of claim 1, wherein said feedback signal varies in the same sense as the displacement caused by said servomotor.

3. An apparatus for stabilizing the steering force in an aircraft, comprising a steering column, and controlled means for said stabilizing, pivoting means and steering linkage means for connecting said steering column to said controlled means in an articulated manner, flight speed sensing means for measuring the flight speed, circuit means connected to said flight speed sensing means for producing a speed dependent signal, servomotor means, spring means and pivot connecting means for operatively connecting said servomotor means to said steering column for imparting a reaction force to said steering column in accordance with the tension state of said spring means, said pivot connecting means securing one end of said spring to said steering column at a point located approximately opposite a point at which said steering linkage means is articulated or pivoted to said steering column, pick-up means connected to said servomotor means for producing a displacement dependent feedback signal, signal combining means connected for receiving said speed dependent signal and said feedback signal to produce a control signal, means connecting an output of said signal combining means to a control input of said servomotor means for modifying said reaction force by the instantaneous spring tension state which signals to the pilot the correct movement direction to be imparted to the steering column.

4. The apparatus of claim 3, wherein said signal combining means comprise a signal adding circuit.

5. The apparatus of claim 3, further comprising a power amplifier opertively connected between said signal combining means and said control input of said servomotor means.

6. The apparatus of claim 3, further comprising a signal limiter opertively connected between said signal combining means and said flight speed sensing means.

7. The apparatus of claim 3, further comprising proportional amplifier means operatively connected between said signal combining means and said flight speed sensing means.

8. The apparatus of claim 7, further comprising vibration damping circuit means including a series connection of a differentiating circuit means and an amplifier, said series connection being connected in parallel to said proportional amplifier.

9. The apparatus of claim 3, wherein said flight speed sensing means comprise a Pitot tube.

10. The apparatus of claim 3, wherein said servomotor means comprise a trim-motor, said apparatus further comprising single pole double throw trimming switch means operable by a pilot, a double pole trimming voltage source, and circuit means connected to said trimming switch means for operatively connecting one or the other pole of said trimming voltage source to an input of said signal combining means.

11. The apparatus of claim 10, further comprising a switch-over switch arranged for directly connecting said trimming switch means to an input of said servomotor means.

12. The apparatus of claim 12, wherein said circuit means for operatively connecting one or the other pole of said trimming voltage source to an input of said signal combining means comprise a proportional amplifier and an integrating circuit connected in series with said proportional amplifier.

13. The apparatus of claim 12, further comprising a switch-over switch arranged for directly connecting said trimming switch means to an input of said servomotor means.