JPH0259692A - Laser radar - Google Patents

Abstract

PURPOSE:To allow an area to be monitored to correspond with an area in which the flight of an aircraft can be executed by controlling the maximum distance detection and the monitoring visual field angle corresponding to the area to be monitored, namely, a beam divergence angle in accordance with an aircraft body speed. CONSTITUTION:A laser light is offered to a beam expander 3 through a half mirror 7 from a laser transmitting part 1, a prescribed beam divergence angle is given and the light is received by a scanning optical system 4. The scanning optical system 4 scans this received light at a monitoring visual field angle of a solid angle psi, and an input received light advances in the direction opposite to a feeding light, offered to a received light processing part 2 through the half mirror 7 and a mirror 6 and brought to signal processing. An optical system control part 5 receives aircraft body speed data from a speed indicator 8, calculates the maximum detection distance to be monitored, and thereafter, calculates a necessary beam divergence angle and the monitorvisual field angle, and brings the beam expander 3 and the scanning optical system 4 to setting control to this calculated value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a laser radar, and more particularly to a laser radar mounted on an aircraft and used for detecting obstacles on the aircraft's path that may impede flight operations.

[Conventional technology]

Conventionally, in this type of laser radar, the maximum detection distance and monitoring viewing angle of the area to be monitored have been set independently, regardless of the speed of the aircraft.

[Problem to be solved by the invention]

In the above-mentioned conventional laser radar of this type, when attempting to change the course of an aircraft, the larger the speed V of the aircraft due to inertia, the smaller the maximum angle ψ at which the course can be changed after a certain period of time Δ.

FIG. 3 is an explanatory diagram showing the relationship between the aircraft speed and the maximum angle at which the course can be changed, and FIG. 4 is an explanatory diagram showing the relationship between the aircraft speed and the possible flight range.

In FIG. 3, Δt is the time from when the pilot visually recognizes an obstacle to when the pilot takes a maneuvering action to safely evacuate the aircraft.

The range in which the aircraft can fly within a certain period of time Δ depends on the speed of the aircraft, as shown in FIG. Therefore, the fourth
The conventional method has a drawback in that it cannot detect an obstacle 104 indicated by an X mark outside the monitoring area 103 indicated by a dotted line in the figure.

In addition, in order to detect these obstacles 104, it is necessary to monitor the area indicated by the dotted line in FIG. 3, which requires a higher output laser transmitter, making the laser radar larger. There was a drawback.

Furthermore, even if an obstacle 104a is detected within the monitoring area 103 by the conventional method shown by the dotted line, depending on the speed of the aircraft shown in FIG. The disadvantage is that these obstacles do not obstruct the aircraft and result in unnecessary monitoring.

All of these drawbacks are due to the fact that the area to be monitored is determined regardless of the flight range of the aircraft, that is, the speed of the aircraft.

The object of the present invention is to eliminate the above-mentioned drawbacks and to provide a laser radar which "coincides the area to be monitored with the flight range of the aircraft."

[Means to solve the problem]

The laser radar of the present invention is a laser radar mounted on an aircraft to detect obstacles on the path, and the spread angle of the laser beam and the monitoring viewing angle are controlled in inverse proportion to the speed of the aircraft, so that the monitoring viewing angle is adjusted to the speed of the aircraft. It is constructed with means for inversely proportional control to match the monitoring area with the flightable area of the aircraft.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a configuration diagram of an embodiment of the present invention, and the laser radar of this embodiment includes a laser transmitter 1, a received light signal processor 2,
It is comprised of a beam expander 3, a scanning optical section 4, an optical system control section 5, a mirror 6, and a half mirror 7, and a speedometer 8 is also shown.

Laser light is provided from the laser transmitter 1 to the beam expander 3 via the half mirror 7, is given a predetermined beam spread angle, and is received by the scanning optical system 4. The scanning optical system 4 scans this received light at a monitoring viewing angle of a solid angle φ, and the input received light travels in the opposite direction to the transmitted light and is provided to the light reception processing section 2 via the half mirror 7 and the mirror 6, where it is sent as a signal. It is processed.

The optical system control unit 5 receives aircraft speed data from the speedometer,
After calculating the maximum detection distance to be monitored, the necessary beam spread angle and monitoring viewing angle are calculated, and the beam expander 3 and scanning optical system are set and controlled to these calculated values.

Next, a method of setting the beam divergence angle θ and the monitoring viewing angle Φ of the optical system control section 5 in this embodiment will be explained using an example.

First, as explained in FIG. 4, the range in which the aircraft can fly varies depending on the speed of the aircraft. Now, match the area to be monitored with this flightable area, and from this the beam divergence angle θ
Let's find the monitoring viewing angle Φ.

FIG. 2 is an explanatory diagram showing the relationship between the monitoring viewing angle and the beam divergence angle in the embodiment of FIG. 1.

First, since the maximum angle ψ at which the aircraft's course can be changed is inversely proportional to the speed V, the monitoring viewing angle Φ is determined by the following equation (1).

Φ=2ψoc"l/v-(1) On the other hand, since the maximum detection distance ρ is proportional to the aircraft speed V,
The area S1 to be monitored remains constant regardless of the speed V of the aircraft, as shown in (2) below.

S, cx=(,2・Φ) 2ζ:x:
(v ・ 1 / ■) 2 - constant... (2
) If the beam divergence angle is θ, the laser beam cross-sectional area S2 at the maximum detection pressure i4ρ can be calculated using the following equation (3).

S2 − yr (ffz θ/2)” ・ (
3) The repetition frequency f of the laser transmitter 1 is calculated by converting equation (3) into (
2), it is determined as in equation (4).

f”=S+, /S2=St/π(ρθ/2)
2...(4) Here, since the repetition frequency f of the laser transmitter 1 is constant, and from equation (3), 81 is also constant, from equation (4), i
θ becomes constant.

Therefore, the beam divergence angle θ is determined as shown in the following equation 5: θα1/fl doctor 1/v (5) Therefore, the monitoring viewing angle Φ and the beam divergence angle θ are determined by the following equations (1) and (5). The optical system control unit 5 executes such optical system control by making it inversely proportional to the speed of the aircraft as shown in FIG.

〔Effect of the invention〕

As explained above, the present invention controls the area to be monitored according to the speed of the aircraft, that is, the maximum distance detection and monitoring viewing angle corresponding to the beam divergence angle. As a result, when the speed of the aircraft is high, it is possible to monitor further distances, and when the speed of the aircraft is slow, it is possible to monitor a wider field of view.

Further, according to the present invention, since the laser radar can be configured with a laser transmitter having a smaller average output, there is an effect that the laser radar can be made lighter and simpler.

FIG.

DESCRIPTION OF SYMBOLS 1... Laser transmitting section, 2... Light receiving signal processing section, 3.
... Beam expander, 4... Scanning optical system, 5...
・Optical system control part 1, 6... speedometer.

Claims (1)

[Claims] In a laser radar mounted on an aircraft to detect obstacles on the path, the spread angle of the laser beam and the monitoring viewing angle are controlled in inverse proportion to the speed of the aircraft, and the monitoring viewing angle is inversely proportional to the speed of the aircraft. What is claimed is: 1. A laser radar comprising means for controlling and matching a monitoring area with a flight area of an aircraft.