LECOS- Research Proposal for a Light Electronic Control System

1.BACKGROUND OF THE PROPOSAL

The invention relates to a control signal transmitting apparatus especially for aircraft. Such control signals are to be transmitted to the control surfaces, for example, the flaps of the elevator assembly, the rudder assembly, and so forth. The transmission is to be accomplished by a passive conductor system.

It is generally known that control signals in an aircraft are transmitted in response to control movements made by the pilot, for example to control the rudder, by mechanical means such as cable pulls, linking rods, rotational shafts, or combinations of such mechanical means. Depending on the type of application, these devices are supplemented by hydraulic or electrical drive means. It is further known in connection with large volume aircraft to employ servo-control systems. Due to the mechanical coupling means interposed between certain rudders in such control systems the operational patterns are positively or rigidly determined. For example, the following operational patterns are so determined: operation of the elevator assembly takes place always symmetrically, operation of the ailerons takes place always in a non-sysmmetrical manner, operation of the landing flaps or air brake flaps always takes place symmetrically.

These fixed operational patterns have the disadvantage that, for example, upon failure of a certain rudder, the remaining still operational rudder might possibly not be available for use in re-establishing the maneuverability. If more specific considerations are taken into account the above mentioned mechanical control systems have a further disadvantage resulting from their vulnerability. Thus, for these purposes electrical servo-control systems have been used in which the transmission of control signals takes place through passive conductors such as coaxial cables. In such a system it is possible to provide the individual operational circuits including the cables leading to the individual adjustment members in a redundant manner, for example in quadruplicate. Thus, such an operational circuit remains, for example, still operational even if three of the respective cables have failed, for example, as a result of combat action. However, the provision of redundant signal transmitting circuit means has, among others, the following weak points. Such systems are sensitive to electro-magnetic disturbing fields such as lightning impact, short circuits and the like. An intermeshed cable network cannot be realized without active elements at the nodal points of the network due to transit time effects and reflection effects. Further, due to the just mentioned effects, the wiring may be carried out in practice only in the form of function related wiring strands. This means that, for example, in a quadruplicate redundancy systemn four cables are required for each adjustment member to be controlled. Additionally, this type of wiring results in a substantial cable weight if cables with a low damping coefficient are used.

According to the magazine "Electronik Praxis" (Electronic Practice), Vol. 11, pg. 34, 1979, it is known to use light conductors for the assembly of data bus systems, for example, on board ships or aircraft or for controlling industrial processes. In a narrower sense the term "data bus" means a conductor for transmitting or relaying of information to which all subscribers are connected. According to the above article, such systems may be constructed as so-called radial or star-bus or as a T-bus. In a radial or star-bus system all connecting conductors converge in a so-called star-coupling member. In a T-bus system each subscriber is connected to the data-bus by a T-coupling member. The light conductor technique has substantial advantages with regard to its use in the control systems of an aircraft, for example, with regard to the weight and reliability. Nevertheless, the radial or star-bus concept as well as the T-bus concept have the disadvantage that each subscriber or rather, each controlled member is connected to the remainder of the system through but one conductor. It follows, that upon failure of such single conductor the functions of the respective subscriber or controlled member must also fail. In connection with the control of an aircraft this would mean that upon failure of a corresponding conductor, for example, due to a localized damage as a result of the failure of other components, possibly a vital control function could be eliminated.

2.OBJECTS OF THE PROPOSAL

In view of the above it is the aim of the invention to achieve the following objects singly or in combination:

to provide an arrangement, especially suitable for the control of aircraft, for transmitting of control signals without any malfunctions due to transit time effects, reflections, and electro-magnetic disturbing fields;

to provide a control signal transmission system which operates passively as an intermeshed conductor network which makes it possible to perform new, preprogrammed control steps or control functions in response to the failure of control elements;

to provide a power supply system the reliability of which is compatible with the reliability of the other elements in the control system to be powered by the power supply system;

to provide a light conductor system for the control of an aircraft which has a high degree of freedom against interference from any possible extraneous light influences; and

to provide a control system especially suitable for the control of aircrafts which has a high reliability factor.

3.SUMMARY OF THE PROPOSAL

According to the invention there is provided a system for the transmission of control signals especially to the control surfaces in an aircraft by a passive conductor system which is characterized by a conductor system comprising a network including repeatedly intermeshed light conductors. The system further includes control members for producing of control instructions in the form of digital light signals. The control members are connected to the light conductor network for transmitting the control instruction signals through signal processors including signal mixers and information systems. Servo-mechanisms are connected to the outputs of the light conductor intermeshed network, whereby the servo-mechanisms are addressable and controllable for effecting the respective control function.

By means of the system according to the invention a substantially increased safety factor has been realized as compared to mechanical, hydraulical, or electrical systems or any combination of such prior art systems. Another advantage of the invention is seen in that it is now possible for the controlled surfaces to perform new types of combinations of excursions or deflections in certain dangerous situations. Thus, even if a rudder should fail, the maneuverability of the aircraft is retained.

According to the invention the present control system is provided with its own energy supply or power supply which comprises a measuring and switching unit which in turn is connected through three transmission units arranged in parallel to the intermeshed network and through the network with a testing unit. This feature of the invention has the advantage that the power supply to the control system has been greatlyimproved as far as the degree of reliability is concerned. Thus, the degree of reliability of the power supply system corresponds to the degree of reliability of the remainder of the system which is powered by the power supply according to the invention.