WO2008116456A1

WO2008116456A1 - All-around collision warning method for helicopters

Info

Publication number: WO2008116456A1
Application number: PCT/DE2008/000505
Authority: WO
Inventors: Daniel Dreyer; Thilo Lees; Volker Gollnick; Gerald Sobotta
Original assignee: Eads Deutschland Gmbh
Priority date: 2007-03-26
Filing date: 2008-03-25
Publication date: 2008-10-02
Also published as: DE102007014878A1

Abstract

The invention relates to a method for the all-around identification of obstacles within the movement area of a helicopter using radar, laser and/or ultrasonic sensors. The ranges of the sensors that are used are selected in accordance with the movement area and the installation locations of the sensors on the helicopter, predetermined scanning movements related to the scanning area are communicated to the sensors and all measuring signals of the sensors received by means of reflection and their individual positions are fed to a common database after an individual signal evaluation that is ordered according to the scanning area, said signals being respectively referenced in terms of distance and direction with the position of the helicopter and being fed in the form of a received reflective field in order to combine all reflective fields and compare them with patterns stored in the database. The complete layout of the movement area that is to be monitored is determined using a subsequent algorithmic evaluation and is displayed as a complete image in the cockpit of the helicopter.

Description

Method for all-around collision warning for helicopters

The invention relates to a method for all-round

Detecting obstacles within the scope of a helicopter using helicopter-associated active radar and / or laser sensors and / or infrared or ultrasonic sensors.

It is known to detect obstacles with a scanning radar or laser beam from a helicopter and to determine distances to the ground with a radar altimeter. Obstacle detection systems based on laser technology are satisfactory with respect to the detection of small objects, but in particular are strongly weather-dependent with respect to their detection steps. Radar systems, on the other hand, are characterized by great weather robustness but low resolution.

Helicopters are regularly exposed to the risk of collision with objects on the ground, especially during takeoff, landing and hovering. This danger is exacerbated in desert areas by dust / sand turbulence = "Brown Out" or in snowy - -

Regions caused by snow turbulence = "White Out", if the turbulence limits the external view very much.

The known laser and radar-based obstacle warning sensors, which detect objects along the trajectory in a forward-looking manner within a limited field of view of typically approximately 30 ° * 40 °, have a sensor range of approximately 1000 m in good visibility. Since they are based on a sensor principle, they either have limitations on the all-weather capability or the detection capability of small objects, eg. B. thin wires of 5 - 10 mm.

According to a proposal which does not belong to the prior art, individual radar sensors operating at different wavelengths for different distances (short-range and long-range) are assigned to predetermined scanning sectors of the sphere surrounding the helicopter and incorporated into an overall system for detecting obstacles provides complete coverage of the relevant helicopter environment, which is not possible with a single scanning radar beam. This increases the safety during takeoff and landing in difficult terrain under adverse visibility, the operational spectrum by warning against collisions during the landing approach of the helicopter in poor visibility and the situational awareness of the pilots in complicated maneuvers. These radar sensors operate as transmitting and receiving units and deliver their signals, which are provided with an identifier, to an identification and evaluation unit, which displays the display units installed in the cockpit Cockpit displays supplied. This can be done either directly or via an intermediate symbol generator.

Using such a radar-based all-round

Although warning system is also a singular obstacle detection of overhead lines and mountain edges possible, but requires the detection of small objects, in particular about existing overland power lines, a vertical incidence of the radar beams on them. This also applies to the lateral distance detection of larger stones, rocks, mountain edges and the like.

The invention has for its object to provide a new method for all-around collision warning using an active system for helicopters, which is all-weather and better than hitherto obstacles and terrain formations, in particular also detect overhead lines and other obstacles and mountain edges and the pilot can.

This object is solved by the features of patent claim 1.

Further features of the invention will become apparent from the dependent claims.

The invention is based on the principle that the defined range of motion of a helicopter must be free from reflections of the sensor signals of potential objects in order to ensure collision freedom, ie, as long as sensor signals emitted in a defined movement space are not reflected by objects the movement within this space of movement is collision free. The range of motion of the helicopter is defined by the rotor diameter, the maximum length of the helicopter - blade leading edge main rotor to blade edge tail rotor - and a safety corridor beyond.

The necessary sensor range is determined by the low translatory speed of the helicopter of approx. 10 - 20 kts during takeoff / landing /

Hover and the necessary reaction times of Pilot (typically: 3 sec.) Helicopter (typically: 4 sec.) And evaluation unit (2 sec. Until the next detection) for safe detection (typically about 8 seconds for these components). By way of example, the detection range is determined for a horizontal speed of 10 kts.

Xπetection = 5.14 m / s * (3 + 4 + 2) sec. = 46.26 m

This results in a rotor radius of z. B. 11 m and a selected safety distance of 10 m, a maximum required sensor range of:

Äsmax = R-Rotor + ^ Safety + ^ Detection = H M + 1 0 JTl + 4 6, 2 6 m = 67.26 m

In order to reliably detect such obstacles, two different types of sensors adapted to the movement space are used simultaneously according to the invention, namely radar and laser or radar and ultrasound sensors or other combinations of ultra-high resolution and weather-independent sensors. -

ren caused by reflections on obstacles measurement signals individually ordered by scanning rooms in terms of distance and direction together on the position of the helicopter combined to reflection fields and fused after determining the reflection density in the space of the helicopter in a database and after comparison with stored in the database patterns using algorithmic Evaluation as the overall situation of the monitored space for movement of the helicopter performing consolidated overall picture in the cockpit of the helicopter are displayed. Thereby, e.g. An approach warning or collision warning is timely.

The radar, laser and ultrasound sensors used are small, reliably operating components - as known, for example, from the distance warning system of vehicle technology - and allow a simple and flexible attachment to the helicopter structure.

If the sensors for carrying out the method according to the invention are constructed, for example, from a radar sensor and a laser sensor, these sensors detect objects of varying degrees due to their physical properties. Laser sensors are able to detect small and thin objects such as B. wires easier to detect than radar sensors. On the other hand, a radar has a large range capability even under different atmospheric conditions, such as dust, rain, snow and fog. Both sensors send their signals according to the given measuring points, so that over the term of the distance and the orientation of the sensor, the direction of the received reflection in each sensor is determined. For each sensor type, an individual signal evaluation of the received reflection field takes place in accordance with its physical characteristics. Likewise, a pattern recognition takes place in each case for each sensor type, so that conclusions can be drawn from the arrangement of the reflections and their distance to defined objects. The objects thus detected by the sensor pairs are stored in a database with their absolute positions. This results in a first overall picture of the situation in which both sensor types can have recognized the same or different objects.

Another algorithmic evaluation checks in the next step on the basis of the sensor-specific positioning accuracy and the type of object, whether it is one and the same or different, possibly closely spaced objects.

Because of the sensor characteristics described above, such a radar and a laser sensor can detect the same high-voltage mast, which is identified by the algorithm as a mast. However, the laser sensor is also able to detect the associated lines, which detects a radar sensor insufficiently reliable. As long as there are no reflection patterns that indicate potentially hazardous objects, the room is considered safe. This will be metallic objects, larger - -

Stones and woods considered as endangered objects. If identical or similar reflections are detected by both sensors at one position range, then the algorithm evaluates this as an obstacle. Are the reflections unstructured and in very low

Density, which can be set as a threshold, distributed in the observation room, is considered as a collision-free space. The evaluation algorithm stores a uniform "overall picture" of the object situation in the database and can then be displayed in different form in the cockpit.

A second form of collision warning is based on the approach that identified and identified in the sensor data fusion objects are positively identified as obstacles and displayed as forbidden waypoints of the crew to display.

The sensor data fusion according to the invention gives for the first time a clear and clear situation presentation. Previous approaches know only the superimposed optical, visual representation of z. For example, video and infrared imagery that are not capable of abstract fusion, which also allows the use of non-image sensors.

The invention is described below in conjunction with the drawing. In detail show:

1a, the scanning sectors of the method for an all-round warning system according to the invention, which are provided with respect to a helicopter of FIG. 2 shows the safe movement space of an example helicopter according to FIG. 1, FIG.

Fig. 3a, the display of a cockpit display for the 3b method according to the invention in strong abstract for "acute collision danger forward", and

Fig. 4 is a functional diagram of the all-around warning system according to the invention.

Since the components and groups required for carrying out the method according to the invention are known per se, their representation has been dispensed with. The paired sensors can be pivoted or, if sufficiently large antennae devices are present, also be fixed to the helicopter. They are - as the figures Ia and Ib show - arranged front, back and sides of the helicopter and the scanning A, B, C, D, and E assigned. Each installation point so two different sensor types, namely radar and laser sensors or radar and ultrasonic sensors are assigned. Below the helicopter such sensor pairs are also arranged in a pivotable or fixed form. The cover area of the sensors below the helicopter covers the front edge of his fuselage and the outer tip of his tail boom; see. Fig. Ia.

The measurement signals of the various sensors are related in terms of distance and direction together on the position of the helicopter by means of the evaluation of the database, not shown. Due to the common reference to a coordinate system, objects can be detected with the different sensors and the detected detections can be verified. If both sensor types detect different objects, these objects are also recorded as potential hazards. If the system is made up of a radar sensor and a laser sensor, these sensors detect objects differently due to their physical properties. The laser sensor is capable of small and thin objects, such. As wires, easier to detect than the radar sensor. By contrast, the radar sensor has a longer range, even under dust, rain and fog. The ranges are, as shown in FIG. 2, chosen around the helicopter and amount to a maximum of 67.26 meters in the present embodiment, of which 10 meters embody the required safety distance.

Both sensor types of each pair transmit their measuring pulses, so that over the runtime the distance as well as the orientation of the sensor, the direction of the received reflections in the respective sensor is determined by means of evaluation electronics. From this, in each case a reflection field and the reflection density in the range of motion of the aircraft Lfz are derived and these data are fed to a database.

For each type of sensor, an individual signal evaluation of the received reflection field takes place in accordance with its physical characteristics. Likewise, a pattern recognition takes place in each case for each sensor type, so that conclusions can be drawn from the arrangement of the reflections and their distance to defined objects. - -

The objects thus detected by a sensor are stored in the database with their absolute positions. This gives a first overall picture of the situation in which both sensor types can have recognized the same or different objects. Another algorithmic evaluation checks in the next step on the basis of the sensor-specific positioning accuracy and the type of object, whether it is one and the same or different, possibly closely spaced objects. Due to the described sensor properties, such a radar and a laser sensor can detect the same high-voltage mast, which is also identified as a mast with the aid of the algorithm. However, the laser sensor is also able to detect the lines that a radar detects only insufficiently reliably.

With the evaluation algorithm, a uniform "overall picture" of the object situation is stored in a database and can then be displayed in different form in the cockpit.

The representation of the collision warning or approach warning in the cockpit is shown in FIGS. 3a and b. The representation of the measurement results of the sensors takes place after preparation of the measurement signals supplied by them with a hazard rating of the determined distances, preferably here with differently colored, hatched here areas designated 10, 11 and 12 and a colorless circular arc 13 of the display in the form of the helicopter HS surrounding circular arcs, for whose center approximately the geometric center of the - -

Helicopter is selected, within a common display, each comprising Figures 3a and 3b. In this way, the entire spatial hazard image of the helicopter is displayed clearly and immediately recognizable to the pilot. For example, an acute danger of collision at the front can be recognized by a red (right, thick hatched), a yellow (left, thick hatched) and a green (left, thin hatched) arc, a slight danger of collision is recognizable on the right by a colorless, ie not hatched, and each a yellow and a red arc, missing collision danger left recognizable by colorless arcs and low risk of collision with respect to the ground recognizable by two colorless and a green circular arc.

- -

C o m p a n c e m e n t i o n s

10 "Yellow" (thick hatched right) circular arc

11 "Red" (thick left hatched) arc

12 "Green" (thin hatched) arc

13 Colorless arc A Sample area B Sample area

C scanning range

D scanning range

E scanning range

HS helicopter

Claims

P a n t a n s p r e c h e

Method for detecting all obstacles within the range of motion of a helicopter using helicopter-associated radar and laser and / or ultrasound sensors, comprising the following steps:

The ranges of the sensors used are selected as a function of the movement space to be monitored and the installation locations of the sensors on the helicopter,

the sensors are given predetermined scanning movements related to the scanning space,

- All received by reflections measuring signals of the sensors with their absolute positions are based on individual, arranged by scanning signal evaluation in terms of distance and direction together on the position of the helicopter and fed after determining the reflection density in the space of movement of the helicopter as a received reflection field of a common database for the purpose of fusion of all reflection fields and - -

same with stored in the database patterns, which determined by means of subsequent algorithmic evaluation of the overall situation of the movement space to be monitored and in the cockpit of the helicopter as a whole

Display is brought.

2. The method according to claim 1, characterized in that for the measurement signals of each sensor type corresponding to the physical properties and the associated reflection field, an individual signal evaluation of each object recognition is performed before it is stored in the database.

3. The method according to claim 1, characterized in that it is checked in the occurrence of reflection patterns in one of the movement spaces, whether in a Po- stierungsbereich determined by distance and direction, both types of sensors have the same or similar reflections recorded over the

Algorithm can be determined as an obstacle, while in unstructured reflections this is considered as a collision-free space.

4. The method according to claim 1, characterized in that is checked after filing a reflection field in the database by further algorithmic evaluation, whether the detected object is one and the same or whether it is different Liehe or closely related objects , A method according to claim 1, characterized in that the determined overall situation as in the direction and relative distance of the reflecting objects in the range of motion of the helicopter as color-coded circular arc sections whose center is the center of gravity of the helicopter is shown in the cockpit.