JP3204313B2 - Aircraft tracking measurement method and system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aircraft tracking system, for example, when an aircraft, such as a helicopter, enters a landing site in a fixed attitude and path, and when a specific surface of the aircraft is visible from the landing site, the position of the aircraft is determined. Measure
The present invention relates to an aircraft tracking measurement method and a system suitable for performing automatic landing support.

[0002]

2. Description of the Related Art A tracking measurement system for measuring a position of a helicopter three-dimensionally for the purpose of, for example, supporting automatic landing of a helicopter is known.

FIG. 11 is a diagram showing an outline of such a tracking measurement system. The measurement-side device mounts an infrared camera or a visible camera and a laser range finder on a gimbal device, and mounts a target light source and a corner cube on a helicopter and tracks the helicopter to perform three-dimensional measurement.

[0004] The gimbal device is automatically tracked by capturing the target light source of the helicopter by an infrared camera or the like mounted on the gimbal to obtain gimbal angle information, and mounted on the helicopter by a laser distance measuring device also mounted on the gimbal device. The distance to the corner cube is measured, and the position of the helicopter is measured three-dimensionally.

[0005]

In the conventional tracking measurement system, it is necessary to install a corner cube and a target light source of a camera very near the corner cube in the aircraft. The target light source of this camera may be a large hot plate or a lamp, but it will cause projections on the aircraft, increasing aerodynamic resistance, deteriorating the flight characteristics of the aircraft, and requiring power supply from the aircraft. There was a problem that there is.

For this reason, it is conceivable to use a high-temperature portion such as an engine to capture the target light source section of the camera with an infrared camera without newly installing the light source section. As shown in the figure, the engine part has unevenness in temperature distribution, etc., and when the detected luminance information is binarized, the area centroid position of the binary image differs according to the binarization threshold, and as the specific position of the aircraft There was a problem that it could not be recognized with high accuracy.

(Object of the Invention) An object of the present invention is to provide an aircraft capable of measuring the position of an aircraft with high accuracy without setting projections or the like which adversely affect the flight characteristics of the aircraft as tracking targets. A tracking measurement method and system are provided.

It is another object of the present invention to provide an aircraft tracking measurement method and system that uses a high-temperature portion such as an engine as a tracking target and does not require power supply for heat generation.

It is another object of the present invention to provide an aircraft tracking measurement method and system capable of tracking an aircraft by using a corner cube and an infrared reflecting plate of an outer plate such as an engine.

[0010]

SUMMARY OF THE INVENTION An aircraft tracking measurement method according to the present invention is characterized in that an infrared reflector that suppresses infrared radiation is attached to an outer plate of a heating portion of an aircraft and a corner cube is attached to the same side surface of the outer plate. Obtain the position information of the infrared reflecting plate by an infrared camera juxtaposed with a laser range finder on a gimbal device, calculate the position of the corner cube based on the position information, and calculate a laser beam from the laser range finder to the corner cube. And measuring the position of the aircraft.

The position information of the infrared reflecting plate is measured as a low luminance area in the luminance of the engine outer panel, and a laser beam output from the laser distance measuring device based on the position information is output from the corner. The gimbal device is controlled so as to irradiate the cube, and the position of the aircraft is three-dimensionally measured from the angle information of the axis of the gimbal device and the distance information from the laser range finder.

Further, the heat generating portion is an engine portion of an aircraft, and the infrared reflecting plate is an infrared reflecting plate having an outer surface mirror-polished.

[0013] The aircraft tracking measurement system of the present invention, heat
Suppress the infrared radiation which is placed on the outer plate of the engine is place
Aircraft having a controlled infrared reflector and a corner cube installed near the engine skin, a gimbal device, a laser rangefinder and an infrared camera juxtaposed on the gimbal device, and the infrared camera obtained by the infrared camera. the position information of the infrared reflecting plate based-out of the corner cube
Position is calculated and composed of a tracking measuring device a laser beam from the laser range finder controls the gimbal device so as to irradiate the corner cube measuring the position of the aircraft. Further, the position information of the infrared reflecting plate obtained by the infrared camera is measured by a low luminance area in the luminance of the engine outer panel, and the position of the aircraft is further determined by the angle information of the axis of the gimbal device and the laser measurement. It is characterized in that it is three-dimensionally measured from distance information from a distance device.

(Operation) An infrared reflector obtained by attaching a corner cube and an infrared reflecting plate whose mirror surface is polished to an engine outer plate to an aircraft such as a helicopter, and obtained by an infrared camera juxtaposed with a laser range finder on the same gimbal. A laser beam is irradiated from the laser distance finder to the corner cube on the basis of the imaging data of (1), and the position of the recopter is measured.
The temperature of the infrared reflector is almost the same as that of the engine skin,
Since the amount of infrared radiation is smaller than that of the engine skin, when the aircraft is imaged with an infrared camera, the brightness of the infrared reflector is observed to be lower than the brightness of the engine skin. The position information can be measured, the position of the corner cube is calculated by the tracking measurement device from the position information, and the gimbal device is controlled so that the laser beam emitted from the laser range finder is applied to the corner cube. The position of the aircraft is measured three-dimensionally from the axis angle of the gimbal device and the distance measured by the laser range finder.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Explanation of Configuration) Next, as an embodiment of the aircraft tracking measurement method and system of the present invention,
The helicopter tracking method and system will be described in detail with reference to FIGS.

FIG. 1 is a diagram showing a configuration example of a helicopter tracking measurement system according to this embodiment. Infrared reflector 1 and corner cube 2 provided on the body of the helicopter, infrared camera 3 for acquiring an infrared image of the helicopter, laser range finder 4 for measuring the distance to corner cube 2, infrared camera 3, laser range finder 4 And controlling the gimbal device 5 based on information from the gimbal device 5, the infrared camera 3 and the laser range finder 4 for simultaneously pointing them in a predetermined direction, and based on information from the laser range finder 4 and the gimbal device 5. It comprises a tracking measurement device 6 that measures the three-dimensional position of the helicopter.

FIG. 2 is a block diagram showing an example of the configuration of the tracking measurement device 6. As shown in FIG. The tracking measurement device 6 includes the infrared camera 3
A target extraction unit 7 that receives the infrared image signal from the infrared extraction unit, extracts the infrared reflection plate 1, and calculates the position and size in the infrared image.
A gimbal control signal calculator 8, which receives target position information in the infrared image and distance measurement distance information from the laser distance measuring device 4, calculates a corner cube position in the image, calculates and outputs a control signal to the gimbal device 5, From the distance measurement information from the laser distance measuring device 4 and the gimbal angle information from the gimbal device 5,
Target position calculator 9 for calculating the three-dimensional position of the helicopter
It is composed of

FIG. 3 is a block diagram showing an example of the configuration of the target extracting section 7. The target extraction unit 7 includes a binarization unit 10, a labeling processing unit 11, an inversion unit 12, and a labeling processing unit 1.
3, a target selection unit 14, a maximum luminance detection unit 15, and a background luminance detection unit 16. The binarization unit 10 extracts an infrared image that exceeds a predetermined binarization threshold from the input infrared images and outputs the extracted infrared image as a binary image. The labeling processing unit 11 processes the binary image and recognizes it as an object, and coordinates the area centroid, the circumscribed rectangle, the luminance, the area, and the horizontal of the object.
Calculate the vertical dimension. The output of the binarization unit 10 is the inversion unit 12
, And inverts the polarity, that is, converts an image that does not exceed a predetermined threshold into an extracted binary image, and outputs it to the labeling processing unit 13. The labeling processing unit 13 performs the same processing as the labeling processing unit 11, and calculates the area centroid coordinates, the circumscribed rectangle coordinates, the luminance, the area horizontal, and the vertical dimension of the object. Using the outputs of the labeling processing unit 11 and the labeling processing unit 13, the target selection unit 14 recognizes the position of the infrared reflection plate and calculates a binarization threshold value used in the processing of the next frame. Also, the maximum luminance detecting unit 15
The background luminance detecting unit 16 calculates the maximum luminance, the maximum luminance point coordinate, and the background luminance of the input infrared image in order to determine the binarization threshold value at the time of starting the tracking.
4 is output.

(Explanation of Operation) Next, the operation of the embodiment of the present invention will be described with reference to the drawings.

FIG. 4 is a diagram showing a time chart of the embodiment of the present invention. An infrared image of the helicopter is captured by the infrared camera 3 at a constant rate, for example, a repetition rate of 60 Hz. The captured infrared image is output to the target extraction unit 7 of the tracking measurement device 6, and is input to the binarization unit 10 of the target extraction unit 7. The binarizing unit 10 extracts a portion of the input infrared image exceeding a predetermined threshold as a binary image.

FIG. 5 is a diagram showing a binary image, in which an engine outer panel portion having a large amount of infrared radiation is extracted as a binary image 1. The output of the binarization unit 10 is further input to an inversion unit 12, and a portion that does not exceed a predetermined binarization threshold is extracted as an inverted image.

FIG. 6 is a view showing an inverted image image, in which the background such as the infrared reflecting plate, the portion of the helicopter body other than the engine outer plate and the sky, which is a portion having a small amount of infrared radiation, is extracted as the binary image 2. . While infrared reflectors emit less infrared radiation from themselves, they reflect background infrared radiation such as the sky and clouds. Therefore, the infrared reflecting plate is extracted by the reversing unit 12.

The binary image 1 output from the binarizing unit 10 and the binary image 2 output from the inverting unit 12 are input to a labeling processing unit 11 and a labeling processing unit 13, respectively. , Circumscribed rectangle coordinates, area, luminance, horizontal dimension, and vertical dimension are calculated. The labeling process starts in response to the input of the binary image, and after the input of the binary image is completed (one frame time), the secondary process is performed and the process is completed. Not explained). The results calculated by the labeling processing unit 11 and the labeling processing unit 13 are input to the target selection unit 14, which recognizes the infrared reflection plate, calculates the area centroid coordinates, and uses the area centroid coordinates in the next frame in the binarization unit 10. A binarization threshold is calculated.

A method of recognizing an infrared reflector performed by the target selection section 14 will be described with reference to the binary image images shown in FIGS. From the binary image 2, as shown in FIG.
It is extracted as two objects, that is, a helicopter body part and a background part other than the infrared reflector and the engine skin, which have a small amount of infrared radiation. The labeling processing unit 13 calculates the coordinates of the center of gravity of each area, and selects an infrared reflecting plate from the coordinates.

From the binary image 1, an engine part having a large amount of infrared radiation is detected as shown in FIG. Since the area of the engine portion is known from the circumscribed rectangle coordinates, and the infrared reflection plate is attached to the engine outer plate, the circumscribed rectangle calculated by the labeling processing unit 11 out of the area barycenter coordinates calculated by the labeling processing unit 13 It is determined that the one inside is an infrared reflector.

Next, a method of calculating the binarization threshold value in the target selection section 14 will be described. FIG. 7 is a diagram showing a luminance distribution and a luminance level in a line passing through the engine portion and the infrared reflection plate. The binarization threshold value is an intermediate value between the luminance level of the engine portion calculated by the labeling processing unit 11 and the luminance level of the infrared reflector calculated by the labeling processing unit 13 and recognized by the target selection unit 14. Set to be. Thereby, the engine part and the infrared reflecting plate can be separated by the binarization processing.

Next, the operation of the gimbal control signal calculator 8 of the tracking measurement device 6 will be described. First, the target extraction unit 7
A method of calculating the coordinates of the corner cube 2 from the coordinates of the area centroid of the infrared reflecting plate calculated in the above will be described. FIG.
FIG. 2 is a view showing a positional relationship among an infrared reflecting plate 1, a corner cube 2, an infrared camera 3, and a laser distance measuring device 4 shown in FIG. 1. For simplicity, the infrared reflecting plate 1 and the corner cube 2 are mounted on the same plane. And the positional relationship between the devices is defined as follows.

Xh: Actual distance between the infrared reflector and the corner cube (horizontal direction) [m] Yh: Actual distance between the infrared reflector and the corner cube (vertical direction) [m] Xs: Infrared camera axis and laser range finder axis Actual distance (horizontal direction) [m] Ys: Actual distance (vertical direction) between the infrared camera axis and the laser range finder axis [m] R: Distance measurement distance by the laser range finder [m] ΔX: With infrared reflector Actual distance of tracking target point (horizontal direction)
[M] ΔY: Actual distance between infrared reflector and tracking target point (vertical direction)
[M] Xt: Actual size of infrared reflector (horizontal direction) [pixels] Yt: Actual size of infrared reflector (vertical direction) [pixels] IFOV: Instantaneous viewing angle of infrared camera (viewing angle of one pixel) [rad] FIG. 9 is a diagram showing the positional relationship between the area center of gravity of the infrared reflector, the tracking target point, and the tracking pull-in point on the infrared camera imaging screen. The positional relationship on the infrared camera imaging screen is defined as follows.

Δx: distance (horizontal direction) of the infrared reflector and the tracking target point on the imaging screen (pixels) Δy: distance (vertical direction) of the infrared reflector and the tracking target point on the imaging screen (pixels) xg : Area barycenter coordinate of infrared reflector (horizontal direction) [pixel] yg: Area barycenter coordinate of infrared reflector (vertical direction) [pixel] xc: Tracking target point coordinate (horizontal) [pixel] yc: Tracking target point coordinate (Vertical direction) [pixels] xt: horizontal dimension of infrared reflector [pixel] yt: vertical dimension of infrared reflector [pixel] Further, the attitude angle of the helicopter is as follows. However, when the plane on which the infrared reflecting plate 1 and the corner cube 2 are attached faces the infrared camera 3, 0 is set.
rad (the state of FIG. 8).

Roll angle: Φ [rad] Yaw angle: Ψ [rad] With the above definitions, the actual distances ΔX, ΔY between the infrared reflector and the tracking target point are calculated from FIG.

ΔX = XhcosΨ−Xs, ΔY = Yhc
osΦ−Ys [m] Here, the attitude angle of the helicopter is calculated using the size of the infrared reflector calculated by the target extracting unit 7. Φ = Ψ =
The imaging size xt0 of the infrared reflector when assuming 0,
yt0 is calculated as follows.

Xt0 = Xt / R / IFOV, yt0 = Y
The attitude angle of the t / R / IFOV helicopter is calculated by the following equation.

CosΨ = xt / xt0, cosΦ = yt / yt0 The distance Δx between the infrared reflector and the tracking target point on the imaging screen,
Δy is calculated by the following equation using the distance R and the instantaneous viewing angle IFOV.

Δx = ΔX / R / IFOV, Δx = ΔX /
R / IFOV [pixel] The coordinates of the tracking target point (xc, yc) on the imaging screen are calculated by the area barycentric coordinates (x
g, yg), the position is (Δx, Δy) apart, and is calculated by the following equation.

Xc = xg + Δx, yc = yg + Δy The positional error between the coordinates of the tracking target point (xc, yc) and the tracking pull-in point (x0, y0), which is the axis of the infrared camera, is the tracking error, and is proportional to the tracking error angle. This signal becomes a command signal for the gimbal device. Since the relationship between the error angle and the command signal is a known technique, it will not be described here.

The target position calculator 9 expresses the position of the helicopter in a polar coordinate format based on the distance R measured from the laser range finder 4 and the gimbal axis angles θ and φ from the gimbal device 5, and outputs the result to an external device. I do.

The foregoing has described a method of tracking a helicopter in a steady state. When tracking and measurement are started, since there is no information on the target level of the previous frame, the threshold value for binarization needs to be determined by a method different from that described above. Further, since the distance to the helicopter is unknown, the position of the corner cube needs to be calculated by a method different from that described above. Hereinafter, a method of calculating the initial binarization threshold value of tracking and measurement and a method of calculating the position of the tracking target point will be described.

Maximum luminance calculating section 15 in target extracting section 7
In the infrared image output from the infrared camera 2,
The maximum luminance is calculated and output to the target selection unit 14. here,
The maximum brightness is the brightness of the engine part. The background luminance calculation section 16 calculates the average luminance of the background and calculates the target selection section 14.
Output to Since the position of the infrared reflector is still unknown, the background brightness is the brightness of the sky or the like, and it is difficult to calculate the brightness of the infrared reflector 1. Accordingly, the target selection unit 14 calculates the binarization threshold value of the next frame by predicting the luminance level of the infrared reflector using the following equation. FIG. 10 shows the luminance distribution on a line passing through the infrared reflection plate of the outer plate of the engine part and each luminance level.

Th = (Imax−Ir) × α + Ir Ir = (Imax−Ib) × ε + Ib Th: binarization threshold value Imax: maximum luminance I
b: Background luminance Ir: Predicted luminance of infrared reflective plate ε: Average emissivity of infrared reflective plate α: Value taking 0 <α <1 (for example, 0.5) According to the time chart shown in FIG. The result of the binarization threshold set as described above is reflected. When the results of the labeling processing unit 11 and the labeling processing unit 13 become valid in the target selection unit 14,
If it is determined that the infrared reflecting plate has been detected, the method is switched to the above-described steady state method.

After the infrared reflector is detected, the position of the co-cube is calculated by the following method. As described above, the actual dimension of the infrared reflector 1 and the dimension on the infrared image have the following relationship.

Xt0 = Xt / R / IFOV, yt0 = Y
t / R / IFOV That is, since the actual dimensions of the infrared reflector 1 and the dimensions on the infrared image are measured, the distance R can be estimated by the following equation.

R = Xt / xt / IFOV or R =
Yt / yt / IFOV Considering the change in the attitude angle of the helicopter, it is desirable to use the shorter one of the two distances calculated above (when the attitude angle is not 0, xt or yt is observed to be small). Therefore, the above calculation distance becomes longer). Since the distance R has been estimated, the position of the tracking target point can be calculated as in the steady state method.

Δx = ΔX / R / IFOV, Δx = ΔX /
R / IFOV [pixel] xc = xg + Δx, yc = yg + Δy After that, the output of the target position detector 9 becomes valid.

In the above-described embodiment, under the assumption that the amount of infrared radiation from the engine portion of the helicopter is the maximum, the maximum luminance detecting section 15 sets the engine portion to the maximum luminance in the infrared image. In order to reduce the influence of clouds and the like, the maximum value can be detected by using a contrast box method or the like to improve the accuracy of extracting a target helicopter.

Further, in the above-described embodiment, the description has been made on the case where the image of the entire screen is processed. However, it is configured such that the processing area is limited by applying a gate as generally used. You may. The mounting position of the infrared reflection plate has been described using the example of the engine outer plate portion.
In the present invention, the present invention is not limited to the engine portion, but generally may be any portion having a high temperature, and can be applied to the outer plate portion.

[0046]

According to the present invention, the targets of an infrared camera are a high temperature portion such as an engine and an infrared reflector,
Since it is not necessary to newly install a large target light source on the aircraft, it is possible to measure the position of the aircraft without installing projections or the like that adversely affect the flight characteristics of the aircraft.

The aircraft is equipped with only the infrared reflector and the corner cube, and it is not necessary to supply electric power for heat generation. Therefore, it is possible to reduce the power consumption of the limited power supply of the aircraft. .

Further, by using an infrared reflector installed on an aircraft as a reference, a laser beam can be accurately applied to a corner cube which is a laser target, so that distance measurement and position measurement can be performed with high accuracy. Is possible.

Further, since the change in the attitude angle of the aircraft can be estimated from the shape of the infrared reflecting plate imaged by the infrared camera, even when the attitude of the aircraft changes, the laser beam is emitted to the corner cube which is the laser target. It is possible to hit exactly.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an overall configuration of a helicopter tracking measurement system according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration example of a tracking measurement device according to the present embodiment.

FIG. 3 is a block diagram illustrating a configuration example of a target extraction unit according to the present embodiment.

FIG. 4 is a time chart showing the operation of the present embodiment.

FIG. 5 is a diagram showing a binary image image.

FIG. 6 is a diagram showing an inverted binary image image.

FIG. 7 is a diagram showing a luminance distribution and a luminance level in a line passing through an engine portion and an infrared reflecting plate.

FIG. 8 is a diagram showing a positional relationship between an infrared reflecting plate, a corner cube, an outside line camera, a laser distance measuring device, and the like.

FIG. 9 is a view showing a positional relationship between an area center of gravity of an infrared reflecting plate, a tracking target point, and the like on an infrared camera imaging screen.

FIG. 10 is a diagram showing a luminance distribution and the like on a line passing through an infrared reflecting plate of an outer plate of an engine portion.

FIG. 11 illustrates a prior art helicopter tracking system.

FIG. 12 is a diagram showing a temperature distribution of a high temperature portion such as an engine and a binary image thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Infrared reflecting plate 2 Corner cube 3 Infrared camera 4 Laser distance measuring device 5 Gimbal device 6 Tracking measuring device 7 Target extraction unit 8 Gimbal control signal calculation unit 9 Target position calculation unit 10 Binarization unit 11, 13 Labeling processing unit 12 Inversion Unit 14 Target selection unit 15 Maximum luminance detection unit 16 Background level detection unit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01S ⁷ /48-7/51 G01S 17/00-17/95 G01S 3/78-3/789

Claims (8)

(57) [Claims] 1. An infrared camera in which an infrared reflector for suppressing infrared radiation is attached to an outer plate of a heat generating portion of an aircraft and a corner cube on the same side surface of the outer plate, and a laser distance measuring device is juxtaposed on the same gimbal device. Acquiring the position information of the infrared reflecting plate, calculating the position of the corner cube based on the position information, and irradiating the corner cube with a laser beam from the laser range finder to measure the position of the aircraft. Aircraft tracking measurement method. 2. The aircraft tracking measurement method according to claim 1, wherein the position information of the infrared reflecting plate is measured as a low luminance area in the luminance of the engine outer panel. 3. The gimbal device is controlled so that a laser beam output from the laser range finder is radiated to the corner cube based on the position information. 3. The aircraft tracking measurement method according to claim 1, wherein the position of the aircraft is three-dimensionally measured from the distance information from the vessel. 4. The aircraft tracking measurement method according to claim 1, wherein the heat generating portion is an engine portion of the aircraft. 5. The infrared reflecting plate according to claim 1, wherein the infrared reflecting plate is an infrared reflecting plate whose outer surface is mirror-polished.
4. The aircraft tracking measurement method according to 2 or 3. 6. An aircraft having an infrared reflecting plate for suppressing radiation of infrared rays installed on an outer panel of an engine, which is a heat generating portion, and a corner cube installed near the engine outer panel, a gimbal apparatus, and the gimbal apparatus. a laser range finder and an infrared camera collocated above, based-out the on position information of the infrared reflecting plate obtained by the infrared camera
An aircraft tracking measurement system configured to calculate a position of a corner cube, control the gimbal device so that a laser beam is emitted from the laser range finder to the corner cube, and measure a position of the aircraft. 7. The aircraft tracking measurement system according to claim 6, wherein the position information of the infrared reflecting plate acquired by the infrared camera is measured by a low luminance area in the luminance of the engine outer panel. 8. The aircraft tracking measurement system according to claim 7, wherein the position of the aircraft is measured three-dimensionally from angle information of the axis of the gimbal device and distance information from a laser range finder.