FR2499721A1 - METHOD AND DEVICE FOR DETECTING HAZARDOUS OBSTACLES FOR AN AIRCRAFT - Google Patents

Abstract

METHOD AND DEVICE FOR DETECTION OF OBSTACLES DANGEROUS FOR AN AIRCRAFT AND, IF ANY, DELIVERY OF AN ALARM SIGNAL IN THE PRESENCE OF OBSTACLES, AND IN PARTICULAR TOWERS, PYLONES, ELECTRIC LINES, ETC., DANGEROUS FOR A HELICOPTER FLYING AT LOW ALTITUDE. THE PROPAGATION TIMES OF AN ACOUSTIC SIGNAL EMITTED BY TRANSMITTERS 1, 2 AND OF AN ACOUSTIC SIGNAL REFLECTED BY THE OBSTACLE ON RECEIVERS ARE MEASURED BETWEEN THE AIRCRAFT AND THE OBSTACLE. HIGH FREQUENCY ACOUSTIC SIGNALS IN THE ULTRASONIC RANGE ARE USED. THE MEASURED PROPAGATION TIMES ARE TAKEN BY A COMPUTER 14, THEN CONVERTED INTO DISTANCES BETWEEN THE AIRCRAFT AND THE OBSTACLE.

Description

The present invention relates to a method for the detection

  dangerous obstacles for an aircraft and, where appropriate, the deli-

  warning signal in the presence of obstacles, and in particular

  towers, pylons, power lines, etc. dangerous for a helicopter

  low-flying flying crab, as well as a process for

said process.

  The patent of the Federal Republic of Germany No. 26 43 526

  describes an optoelectronic alarm device for aviation pilots.

  naves and in particular helicopters flying at low altitude, with an on-board laser rangefinder. The laser beam of the rangefinder explores the interesting terrain in circles, spirals or lines. An indicator is provided, observed by a pilot and providing an image of the scene explored. In order to provide a clear indication of obstacles, especially those in front of a structured background, the echoes of the laser beam produced by obstacles are transmitted to the indicator only when the distance between an indicated obstacle and the aircraft has a value discontinuity

  predetermined minimum relative to a previous echo.

  The subject of the invention is a method and a device for signaling

  barriers for aircraft and in particular helicopters

  can be used regardless of the weather over distances

  averages from 80 to 400 m for example.

  According to an essential characteristic of the invention, the propagation times of an emitted acoustic signal and of a reflected acoustic signal are measured between the aircraft and an obstacle; high frequency acoustic signals in the ultrasonic range are used; and the measured propagation times are stripped by a

  calculator, then converted into distances between the aircraft and the obstacle.

  According to another characteristic of the invention, signals

  Frequency modulated signals are used for the rejection of para-

  sites. According to another characteristic of the invention, movable acoustic transmitters and receivers in elevation and / or azimuth are used. The invention has the following advantages: independence of bad weather and possibility of realization of a device relatively

economical, compact and lightweight.

  Other features and advantages of the invention will be better

  understood using the detailed description below of an example

  of achievement; whose single figure represents the diagram of the device

mounted on an aircraft.

  The device comprises two acoustic transmitters 1 and 2, each of which is assigned a not shown acoustic receiver. The acoustic emitters, which in the example shown form a constructive unit with the corresponding acoustic receivers, are each controlled in rotation by a mechanical drive 3 or 4 about any axis, preferably perpendicular to the direction of transmission and reception. Transmitters 1 and 2 deliver acoustic signals of high frequency, in the ultrasound range, that obstacles located in the aircraft's path reflect on the

  corresponding acoustic receivers.

  A transmitter stage 5 or 6 is arranged upstream of each acoustic transmitter 1 and 2, and a receiver circuit is arranged upstream of each acoustic receiver. An oscillator 10 controlled by a clock 9 delivers high frequency oscillations to the emitter stages 5 and 6, whose output power can be controlled as a function of frequency. The clock 9 also controls a control device 11, acting in connection with the receiver fixtures, and two counters

  arrhythmic devices 12 and 13. The device 11 can control

  the inputs of the start-stop counters 12 and 13 are each connected to an output of a transmitter stage 5, 6 or of a receiver circuit 7, 8, while the outputs of the start-stop counters 12 and 13 are each connected to an input of a computer 14. Two other inputs of the computer 14 are

  connected to unrepresented angle sensors, assigned to

  3 and 4, and measuring the angular position of

  acoustic transmitters 1, 2 and corresponding acoustic receivers.

  dent. The computer 14 calculates the distance between the aircraft and the obstacle from the measured propagation times of the signals

  Acoustic information, as well as information on the shape of the obstruction

  tackle, from the angular position of the acoustic transmitters 1, 2 and the corresponding acoustic receivers. The results of the calculator 14 may be transmitted to a processing circuit for representation on an indicator 16. The representation may be an alphanumeric indication of the distance or azimuth angle or elevation of the detected obstacle, or a surface representation, in the form of a favorable ergonomic configuration on

the indicator 16.

  In the example shown, the clock 9 provides the time control

  the device for the signaling of obstacles. The oscillator delivers high frequency oscillations to the emitter stages 5 and 6, so that they produce an output power that is a function of

  frequency. This output power is radiated by the transmitters

  combined acoustic receivers 1 and 2. When the ultrasonic signal

  reached an obstacle, the reflected signal is received by the transmitters-

  combined acoustic receivers 1 and 2 and then converted by montages

  receivers 7 and 8 has a compressor filter driven in a pulse of

  retaining the start-stop counters 12 and 13. The latter receive a start signal of the emitter stages 5 and 6 at the time of emission of the ultrasonic signal, so that they memorize the reception of the stop pulse the time of forward and backward propagation of the ultrasonic signal to the obstacle. Data on propagation times and angular positions of acoustic transceivers 1 and 2, provided by mechanical drives 3, 4

  and the angle sensors, are translated by the computer 14.

  The use of acoustic transducers allows a strong focus of the acoustic signals, while the use of frequency modulated signals ensures the rejection of spurious signals. He is in

  Moreover, it is possible to provide a large number of transmitters and receivers

  ticks arranged along lines and columns, in order to produce

  information of direction and distance, as well as information

  relating to the shape of one or more obstacles.

  Of course, various modifications may be made by those skilled in the art to the principle and to the devices which have just been described solely by way of nonlimiting examples, without

depart from the scope of the invention.

Claims (12)

claims   1. Method for detecting dangerous obstacles for an aircraft and, if necessary, issuing an alarm signal in the presence of obstacles, and in particular towers, pylons, power lines, etc. dangerous for a helicopter flying at low altitude, said method being characterized by measuring the propagation time of an acoustic signal emitted and an acoustic signal reflected between the aircraft and an obstacle; the use of high frequency acoustic signals in the ultrasound range; and the counting of the times   spreads measured by a calculator and their conversion into   between the aircraft and the obstacle.   2. Method according to claim 1, characterized by the use of acoustic transducers providing a focused focus of acoustic signals.   3. Method according to one of claims 1 and 2, characterized by   the use of frequency modulated signals for the rejection of spurious signals.   4. Process according to any one of claims 1 to 3, characterized   a plurality of acoustic transmitters and receivers, arranged in rows and columns, for producing direction and distance information, as well as information relating to the shape of a several obstacles.   5. Method according to any one of claims 1 to 4, characterized   through the use of mobile transmitters and receivers in elevation and / or azimuth.   6. Device for implementing the method according to any one   Claims 1 to 5, characterized in that two acoustic emitters   ticks (1, 2) are provided, each with an acoustic receiver cor-   respondant, a transmitter stage (5, 6) being arranged upstream of each transmitter and a receiver circuit (7, 8) upstream of each receiver;   an oscillator (10) controlled by a clock (9) delivers oscillations   high frequency transmitting stages (5, 6); the clock <9) drives a control device (11), acting in connection with the receiver assemblies (7, 8), and two start-stop counters (12, 13), whose inputs are each connected to an output of a transmitter stage (5, 6) or receiver circuit (7, 8); and meter outputs   arrhythmic signals (12, 13) are each connected to an input of a calcula-   (14), which calculates the distance between the aircraft and the obstacle to   from the measured propagation times of the acoustic signals.   7. Device according to claim 6, characterized in that the power   the output stage of the transmitter stages (5, 6) is controlled according to frequency.   8. Device according to claim 6, characterized in that the control device (11) controls compressor filters located   in receiver assemblies (7, 8).   9. Device according to claim 6, characterized in that the   acoustic transmitters (1, 2) and the corresponding acoustic receivers.   people turn from any angle.   Device according to claim 9, characterized in that the mechanical drives (3, 4) are equipped with angle sensors for the angular positioning of the acoustic emitters (1, 2) and   corresponding acoustic receivers.   11. Device according to any one of claims 6, 9 and 10,   characterized in that the outputs of the angle sensors of the drive   mechanical elements (3, 4) are each connected to an input of   latour (14) which, from the differences in propagation time of the acoustic signals and the angular position of the emitters   acoustics (1, 2) and corresponding acoustic receivers,   provide information on the shape of the obstacle.   Device according to one of claims 6 and 11, characterized   by mounting downstream of the computer (14) of a processing circuit (15) and an indicator (16).