MAKOVEC, Boštjan (Dolga Poljana 25a, 5270 Ajdovščina, SI)
TOMAŽIČ, Tine (Goriška cesta 2, 5270 Ajdovščina, SI)
MAKOVEC, Boštjan (Dolga Poljana 25a, 5270 Ajdovščina, SI)
| Patent claims 1. Interface for control of aircraft trim system, which is an electro-mechanical human interface used for intuitive control of secondary aircraft control surfaces i.e. trim surfaces and is directed to the system and method of controlling the electric and/or hydraulic actuation of aircraft trim surfaces by means of operating a single cockpit handle, enabling all possible motion degrees of freedom as well as concequent actions of the aeroplane, characterized in that the interface comprises the dome (1) acting as the housing, the inner spherical element (2) which slides on the inside of the lower dome (1), providing for smooth motion of the hat element (3), which is permanently attached via a stem, whereas the hat element (3) has an ergonomical shape and/or a recess on the top allowing for adequate grip of pilot's hand or finger; below the dome (1) there are four compression springs (4) and one torsion spring (5); the movements of hat element (3) are bounded and guided by grooves (6), which are made into the inner side of the dome (1); adjecent to the groves are the pinheads on the inner spherical element (2) which slide over the groves (6) to guide the motion of the hat element (3); the bottom enclosure (7), houses motion sensing elements (8) of the interface. 2. Interface according to claim 1, characterized in that the bottom enclosure (7) is executed in form of a printed circuit board. 3. Interface according to claim 1, characterized in that there are from one to six sensing elements (8), which can be of switch type where behaviour is required, a potentiometer, where displacement progressive behaviour is required, an optical or magnetic encoder for added environmental resistance or a force transducer where force progressive motion behaviour is preferred. 4. Interface according to claims 1 to 3, characterized in that the integration and usability of the the interface in the aircraft trim system can be realised by direct connect, by connection via logic circuitry or by connection via flight control law computer. |
The present invention relates to a novel user interface for control of aircraft trim system, which is an electro-mechanical human interface used for intuitive control of secondary aircraft control surfaces i.e. trim surfaces. More particulary, the present invention is directed to the system and method of controlling the electric and/or hydraulic actuation of aircraft trim surfaces by means of operating a single cockpit handle.
While there are many solutions for the mechanical actuation of an aircraft trim surface, presented in patents US 7021587 Bl, US 2008237402, CA446707 A, all the mentioned solutions focus purely on the movement of the trim surface itself and completely disregard the prospects of the human interface with which the pilot controls the trim system. Traditionally the human interface for a 3-axis aircraft trim system, i.e. aileron, elevator and rudder trim surfaces, consists of three individual rocker- or toggle-style switches, where each represents a separate human interface for controlling the actuation of a single axis of aircraft trim. Such a human interface consisting of three human interfaces i.e. switches is normally located on the instrument panel of the aircraft.
Alternatively, solutions exist where the elevator- and aileron- or elevator- and rudder- trim human interface is joined in form of a four-way hat switch, however the third axis of the aircraft trim system remains to be controlled separately. Use of a four-way hat switch allows for part of the aircraft trim system to be installed onto the primary control lever of the aircraft, i.e. central control stick, central yoke, side control stick, side control yoke and others, but the third axis still resides outside of pilot's immediate reach.
The ergonomics of all cockpit levers is strictly determined by aircraft certification standards. Focusing on General and Transport Category rules i.e. relevant Aviation Part -23 and -25 certification, also the trim system human interface is to be designed so that it is intuitive and not confusing to the pilot. Whichever the shape and form of the aircraft trim system human interface, it must be executed so that its movement foward yields a nose-down elevator trim effect, its backward movement yields nose-up elevator trim effect, left movement induces left- roll aileron trim effect and right movement induces right-roll aileron trim effect. The movement or rudder trim human interface is to resemble the principle of the aileron one.
The above has led to a new, fully intuitive style of human interface for a full three-axis aircraft trim system. The interface presented on drawing 1 has the capability of controlling/actuating all three axis of the aircraft control system using a single control lever in the cockpit, which can be positioned either on the primary control lever of the aircraft, or elsewhere within reach of the pilot(s); the size of interface can span anywhere from a minitature fingertip operated version to a palm-size unit. The design of the interface allows the pilot to intuitively control a single trim axis, two trim axis or even all three trim axis at the same time.
The features and advantages of the present invention will become more fully apparent from the following detailed description and the accompanying drawings, in which:
Fig. 1 : axonometric view on interface,
Fig. 2: cross-section view on interface,
Fig. 3 : axonometric view on interface with all possible motion degrees of freedom,
Fig. 4 a, b, c: presentation of all possible motion degrees of freedom as well as concequent actions of the aeroplane.
The interface is pictured on Fig 3 from top view and on Figs. 4 a, b, c from side and all possible motion degrees of freedom as well as concequent actions of the aeroplane are shown. Pushing the interface forward or backward triggers the elevator trim with forward i.e. nose- down or backward i.e. nose-up effect. Pushing the interface left or right triggers the aileron trim with left i.e. left roll or right i.e. right roll effect. Twisting the interface left or right triggers the rudder trim with yawing left i.e. nose left or yawing right i.e. nose right effect.
The construction of the interface consists of the following major components: the dome 1 acting as the housing, the inner spherical element 2 which slides on the inside of the lower dome 1, providing for smooth motion of the hat element 3, which is permanently attached via a stem. The hat element 3 has an ergonomical shape and/or a recess on the top allowing for adequate grip of pilot's hand or finger. Below the dome 1 there are four compression springs 4 . and one torsion spring 5. Their role is to neutralise/centralise the position of the hat element when the interface is not being manipulated.
Parts 2 and 3 are permanently bonded via a stem which can be screwed or otherwise attached. Whenever the hat element 3 is displaced into any of the three degrees of freedom, which correspond to forward-aft translation, left-right translation and left-right twist, the inner spherical element follows this movement and transfers them on the sensing elements 8.
Combinations of different type/style sensing elements are possible. The movements are bounded and guided by grooves 6, which are made into the inner side of the dome 1. Adjecent to the groves are the pinheads on the inner spherical element 2 which slide over the groves to guide the motion of the hat element 3.
The bottom enclosure 7, which can also be executed in form of a printed circuit board, houses motion sensing elements 8 of the interface. Depending on the type used, there can be from one to six sensing elements. The sensing element can be of switch type where ON/OFF behaviour is required, a potentiometer, where displacement progressive behaviour is required, an optical or magnetic encoder for added environmental resistance or a force transducer where force progressive motion behaviour is preferred. In cases where a potentiometer, optic or magnetic encoder or a force transducer is used, the displacement and/or force applied in motion of the interface is proportional to the velocity of trim change. All degrees of freedom of the interface movement have a five degrees symmertical hysteresis field to aviod inadvertant operation of the hat element. Further, the interface can be protected against inadvertant trim change by requiring a vertical down-push on the hat before initiating trim. This is achieved with the addition of vertical touch sticks, which make contact with the sensing elements only when the interface is depressed. Other means of inadvertant trim action, being an electrical, mechanical and/or software lock are also possible.
Integration and usability of the the interface in the aircraft trim system:
a) Direct connect
Only ON/OFF behaviour i.e. the version of interface using switches as sensing elements can be implemented,. This implementation does not require any kind of logic circuitry, as the sensing devices act directly as triggers to the power relays of the electric or hydraulic trim system. Such a system is simple and can be incorporated also into existing aircraft trim system with ease, however does not offer advanced functionality. b) Connection via logic circuitry Addition of logic circuitry to the interface allows for a more sophisticated control mode to be used. In addition to ON/OFF behaviour as described in a) the interface can operate in progressive displacement and/or force mode, depending on the choice of sensing elements. In this case, the displacment and/or force applied in motion of the interface is proportional to the velocity of trim change. Logic circuitry translates the displacements and/or forces induced on the interface into control signals for trim servo motors' direction and velocity of rotation. The sensing elements are wired to a AD converter via an amplifier (if required), then the microprocessor translates digital values into analogue or digital control signals for the servo motors of each individual trim axis. For non-complex aircraft with an electric and/or hydraulic means of actuating primary control surfaces, the interface can also be used as a primary flight control for all three axes of motion (roll, pitch, yaw), occupying only one hand of the pilot. The data interface between the interface, logic circuitry and servo motor effectors can be realised using conventional wires, optical fibre and means of magnetic, capacitive or wireless tranmission.
c) Connection via Flight Control Law(s) computer(s)
Having implemented the interface into the aircraft Flight Control Law(s) computer(s) adds the possibility of using the interface interface not only as the human interface for a three-axis trim system, but also as an interface for communicating with the autopilot and/or its use as the alternative primary flight control lever. With progressive displacement and/or force mode, the interface can be used to steer the aircraft along all three axes-of motion i.e. roll, pitch, yaw simultaneously or individually. Doing this only occupies one hand of the pilot.
In all three cases of connectivity the present position of the trim system, i.e. trim indicator, can be displayed on a separate cockpit display, analogue gauge or optical device and/or on the interface itself by using miniature LED indicators in form of an intuitive array of visual emmitors, which can vary in shape and size.
Interface for control of aircraft trim system according to the invention comprises the dome 1 acting as the housing, the inner spherical element 2 which slides on the inside of the lower dome 1, providing for smooth motion of the hat element 3, which is permanently attached via a stem, whereas the hat element 3 has an ergonomical shape and/or a recess on the top allowing for adequate grip of pilot's hand or finger; below the dome 1 there are four compression springs 4 and one torsion spring 5; the movements of hat element 3 are bounded and guided by grooves 6, which are made into the inner side of the dome 1; adjecent to the groves are the pinheads on the inner spherical element 2 which slide over the groves 6 to guide the motion of the hat element 3; the bottom enclosure 7, houses motion sensing elements 8 of the interface.
The interface is executed in form of a printed circuit board. Interface has from one to six sensing elements 8, which can be of switch type where behaviour is required, a potentiometer, where displacement progressive behaviour is required, an optical or magnetic encoder for added environmental resistance or a force transducer where force progressive motion behaviour is preferred. The integration and usability of the the interface in the aircraft trim system can be realised by direct connect, by connection via logic circuitry or by connection via flight control law computer.