GB2262626A

GB2262626A - Automatic vtol control system

Info

Publication number: GB2262626A
Application number: GB9224374A
Authority: GB
Inventors: Wolfgang Alles; Hans-Peter Engelbert; Herbert Friedl
Original assignee: Dornier GmbH
Current assignee: Dornier GmbH
Priority date: 1991-12-19
Filing date: 1992-11-20
Publication date: 1993-06-23
Also published as: FR2686311A1; DE4142037A1; ITTO921021A0; GB9224374D0; CA2085566A1; ITTO921021A1

Description

2262626 1 A TAKE-OFF AND/OR LANDING SYSTEM This invention relates to a

take-off and/or landing system for vertical take-off and landing (VTOL) aircraft.

It is an object of the invention to provide a system which enables a VTOL aircraft to take off from and/or land on a stationary or moving surface, e.g. a ship or a vehicle.

According to the invention a take-off and/or landing system for a vertical take-off and landing aircraft has a take-off/landing site sensor system, a signal processing system, a data link to the aircraft, an aircraft sensor system, an aircraft signal processing system and an aircraft adjusting system, with a device for securing the aircraft on the take-off/landing site, whereby the system permits automatic position holding, automatic take-off from and/or automatic landing on a stationary or moving take-off/landing site. A sensor system at the take/off landing site may incorporate a laser sensor for measuring deviation from an intended landing path and position, and inertial sensors on board the aircraft and/or the ship may be used for monitoring movements of each. Preferably, the system includes an electromagnetic securing device for applying a downward force on the aircraft on landing and for releasing it on take-off, and movement of the aircraft is also controlled by adjusting aircraft lift thrust.

A preferred control system in accordance with the invention, allows an aircraft to take off from and land on a stationary and moving carrier independently even when the latter is travelling at a very high velocity and/or is rolling. This can be performed using a sequence of automatic operations, rendering skilled pilot intervention unnecessary in most circumstances. The aircraft can take off, land, maintain position and fly programmed paths 2 independently but it can also be controlled remotely by a pilot. Both manned and unmanned versions are possible.

In one embodiment of the invention, the take-off/landing site sensor system measures the relative position of the aircraft from the designated landing point. This measurement may be performed by means of laser technology using a laser tracker at the landing site and a mirror system on the aircraft, which together determine the distance and angle of the aircraft with respect to the landing surface.

If the take-off/landing surface is susceptible to movement, the takeoff/landing site sensor system can contain inertial sensor means for determining such movement. In the case of a ship the sensor system can be an inertial sensor system of the ship which operates in conjunction with a ship's computer.

In one embodiment, the data link between the ground or surface and the aircraft transmits the relative position of the aircraft and the movements of the take-off and landing surface to the aircraft.

The aircraft may be arranged to have an inertial sensor system as part of the take-off/landing system for determining its own movements. Using this information and the transmitted movement data concerning the landing site and the relative position data, take-off and landing paths may be automatically controlled.

The aircraft is preferably secured to the landing site by means of electromagnets. If such retaining magnets are provided, the take-off can occur automatically if one or more conditions are fulfilled. Advantageously the automatic take-off only occurs if there is sufficient vertical thrust (produced, for example, by a high angle of 3 incidence of the rotor blades in the case of a rotary wing aircraft) and in a required position of the platform (e.g. 0' angle of roll) as a result of the magnets being automatically switched off.

In the case of an automatic landing, the magnets are switched on when the aircraft first comes into contact with the landing platform. For this purpose landing switches which record contact can be attached to the aircraft. When the retaining magnets are switched on, the lift is automatically reduced (e.g. as a result of collective blade adjustment and/or a reduction in engine speed).

The invention will now be described by way of example with reference to drawings in which:- Figure 1 is a block diagram illustrating elements for the control of take- off of a rotary wing aircraft from the deck of a ship; and Figure 2 is a block diagram illustrating elements for the control of automatic landing of the aircraft on the deck.

Referring to Figure 1, a take-off and landing system in accordance with the invention has, associated with a ship, a landing sensor 10, a ship's computer 12, a first inertial sensing system 14 and a telecommand or remote control transmitter 16 for data transfer with a pilot guidance device 18. Components of the system associated with an aircraft 20 are a telecommand or remote control receiver 22, an INS support filter 24. an internal sensing system INS 26 for the aircraft, a position controller 28, a basic controller 30, a path guidance system 32 and a magnetic securing device 34.

4 The basic controller 30 is used to stabilise the aircraft artificially, and calculates desired values for servo systems from the difference between desired and actual values of a respective flight condition via suitable proportional and integral lock-on systems. The flight condition is characterised by rotational speeds, accelerations, velocities, geodetical position and Euler angle. In the longitudinal movement direction the pitch position and pitch rotational velocity are required, for example. In the side movement direction similar conditions can apply depending on the actual dynamics of the aircraft, the rotational speed of roll and rotational speed of yaw being attributed thereto. The vertical velocity is necessary for the vertical axis.

Depending on the phase lag of the selected signals as a result of measurement and further processing, it may be appropriate to perform compensation using phase correction filters. Notch filters can also be incorporated in order to eliminate the influence of undesirable structure couplings or frequencies.

In the case of automatic take-off, the aircraft lifts off automatically from a stationary or moving landing platform. The aircraft 20 is secured to the ship's deck by means of magnetic securing devices 34. In order to initiate the automatic take-off process, the pilot activates a switch (take-off command). Since the aircraft is to leave the landing platform as quickly as possible, the collective angle is brought practically to its maximum value whilst the aircraft continues to be secured magnetically. This measure causes the aircraft to takeoff from the moving ship's platform with a jump when the magnetic securing device is switched off.

It is advantageous if the aircraft rotor velocity assumes its nominal value as rapidly as possible again when the t h collective angle is raised, before the aircraft lifts off. This prevents the aircraft leaving the vicinity of the platform insufficiently rapidly as a result of losses in performance owing to the rotor velocity being too low.

The aircraft position should be retained stably above the centre point of the take-off/landing platform during and after the automatic take-off process (automatic position holding). If it is indicated that automatic take-off is to be initiated in the zero roll position, one obtains the maximum rotational speed of roll at take-off, on the assumption that the take-off platform is moving sinusoidally (rolling). The control system suppresses this initial value interference as well as external interference in the form of gusts and wind. Therefore the base and position controllers are acted upon by the indications of the path guidance system for height, position, course and vertical velocity.

Referring now to Figure 2, the automatic landing procedure is also initiated by the pilot pressing a key. Landing approach begins with automatic transition to a position above the set-down point.

In this connection the aircraft 20 is to be set down from this state at a predetermined height at a specific relative velocity on the landing site precisely when the roll position of the landing site passes through zero. For this purpose height guidance is converted smoothly into a relative movement with respect to the deck when the aircraft 20 is lowered onto the deck. In the preferred embodiment this occurs by means of a high-precision laser tracker 10.

Using a prediction process, the point at which the roll position of the landing platform passes through zero is calculated in advance. The vertical guidance of the 6 aircraft is arranged such that the landing procedure lasts for a precisely determined amount of time independently of the movement of the landing platform. The landing procedure is thus initiated precisely when the predicted time for the zero roll position coincides with the period defined for the duration of the landing procedure.

The controlled relative lowering velocity is set by analytically calculated indications together with processed telemetric measurement data of the landing platform. In addition, height, course and position are used as command values for the path guidance system.

When the aircraft has made contact with the landing site with the first of four landing switches, for example, which are secured to its underside, the magnetic securing device 34 switches on automatically without external intervention. At the same time, the aircraft lift is reduced as a result of blade adjustment and/or reduction of the engine speed.

A position-holding mode can be selected when the aircraft is in the air. This mode is likewise activated using a switch on the pilot guidance device 18 being activated.

It is to be understood here that position-holding means retaining the geodetical position of the aircraft. The actual position existing when this automatic function is selected is the reference or desired position. It is thus the position-holding command.

In accordance with application and the necessary degree of accuracy of height maintenance, the height measuring signal can be used mixed with the vertical velocity signal by means of complementary filtering.

7

Claims

A take-off and/or landing system for a vertical takeoff and landing aircraft, having a take-off/landing site sensor system, a signal processing system, a data link to the aircraft, an aircraft sensor system, an aircraft signal processing system and an aircraft adjusting system, with a device for securing the aircraft on the take-off/landing surface, whereby the system permits automatic position holding, automatic take-off from and/or automatic landing on a stationary or moving take-off/landing surface.

2. A system according to claim 1, wherein the takeoff/landing site sensor system is arranged to measure the relative position of the aircraft from the intended landing point by means of laser technology.

3. A system according to claim 1 or claim 2, wherein the take-off/landing site sensor system comprises an inertial sensor system for determining the movement of the take-off/landing surface.

4. A system according to any preceding claim, wherein the data link is arranged to transmit the relative position of the aircraft and the movements of the take-off/landing surface to the aircraft.

5. A system according to any preceding claim, wherein the aircraft has an inertial sensor system for determining aircraft movement.

6. A system according to any preceding claim, operable to process the movement data of the take-off/landing surface, the relative position data and the movement data of the aircraft for automatic path guidance on takeoff and landing.

8 8.

7. A system according to any preceding claim, including a magnetic securing device.

A system according to claim 7, operable to cause automatic take-off when there is sufficient vertical thrust and the take-off site is in a required position (0' angle of roll) as a result of a magnet of the securing device being automatically deactivated.

9. A system according to claim 7 or claim 8, operable to cause automatic landing when one or more landing switches attached to on the aircraft makes contact, as a result of magnets of the securing device being automatically switched on and the aircraft lift being reduced.

10. A take-off and/or landing system constructed and arranged substantially as herein described and shown in the drawings.