JP3610907B2 - Object detection system and method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an object detection system and method for detecting the position of an object moving on the ground, and more particularly to an object detection system and method for detecting the position of an object at a low cost with a small number of installations.
[0002]
[Prior art]
A conventional object position detection device is described as an example in International Publication No. W097 / 04337. In this prior art, a plurality of moving body detectors arranged in a grid are provided in a path along which the moving body travels, and based on the arrangement of the moving body detector that detects the moving body, the position, moving direction, The detection of the shape is described.
[0003]
[Problems to be solved by the invention]
However, in the above prior art, when an object enters the effective range of the antenna, a detection signal that “the object is within the effective range of the antenna” is output by one antenna, so the effective range is set wide. Then, the reliability as an object position locating with respect to a detection signal becomes low. For this reason, in the prior art, it is necessary to use only satellites with a high elevation angle from the ground surface to narrow the effective range of artificial satellites used for object detection. As a result, for example, an object in a large space such as an airport apron. It is necessary to install a large number of moving body detectors on the moving road surface, and there is a problem that costs increase. Further, since the number of detectors is large, the processing information increases accordingly, so that the cost for securing the information transmission path and the information transmission apparatus also rises and becomes a problem.
[0004]
An object of the present invention is to provide an object detection system and method capable of detecting the position range of an object with a small number of installations.
[0005]
[Means for Solving the Problems]
In the prior art, in order to determine that an object exists within the effective range centered on the antenna based on information obtained from one antenna, satellite information with a low elevation angle is used by using the elevation angle information obtained from the ground surface of the satellite obtained from a GPS satellite. The method of not using the information of was used.
[0006]
The feature of the present invention is that it has a calculation means as an object detection that specifies the position range of an object based on coordinates from a plurality of antennas and information from all satellites received by each antenna. is there.
[0007]
For objects moving between antennas, the distance between antennas is increased by using a satellite with a low elevation angle by introducing a system that integrates and processes satellite information with a low elevation angle, which was not used in the prior art. The number of installations can be greatly reduced, and the cost can be reduced.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0009]
FIG. 1 shows an example of the configuration of the device of the present invention. Signals from navigation satellites such as GPS are received by a plurality of receiving antennas 1, transmitted by an information transmission device 3 through a signal processing device 2 for the antennas, and aggregated by an information integration unit 5 through a transmission path 4, and as a result. Is output to the result display unit 6. The processing of GPS navigation data in the signal processing apparatus 2, because it is known in general, detailed description is omitted. Further, the processing in the signal processing device 2 and the processing method of transmitting from the information transmission device 3 to the information integration unit 5 via the transmission path 4 are also disclosed in International Publication W097 / 04337.
Detailed description will be omitted.
[0010]
FIG. 2 shows a reception state from receivable GPS satellites. Object detection is basically performed by blocking or attenuating one of the signals Ea to Ef from the satellite. Here, when a plurality of antennas are installed, it can be approximated that the incident angles of the satellite signals to the antennas are all equal as long as the antennas are installed within an arbitrary limited range.
Information such as the individual identification number of the satellite, the elevation angle from the position where the antenna is installed, the azimuth angle, the reception intensity of the radio wave, and the like are obtained from the GPS satellite. And the individual identification number of the antenna are output, the object position range can be calculated by the information integration unit.
[0011]
FIG. 3 is a diagram illustrating a flow of detecting a vertical plane with respect to the ground and a method of detecting that there is an object between two antennas by using two antennas, in an embodiment in which an aircraft is a detection target. There is an aircraft Air that moves in the direction X1 from the antenna A1 to the antenna A2. At this time, since the signal Ea from the satellite being received by the antenna A1 and the signal Ef from the satellite being received by the antenna A2 are blocked, it can be calculated that the aircraft Air is moving between A1 and A2. The setting of the size of the aircraft Air and the distance between the antennas is obtained by actual measurement. Next, differences from the prior art will be described. Previously, satellites with low elevation angles were ignored. This is because the object detection signal is determined by the antenna alone and the object detection signal is output, so that the satellite with a low elevation angle is not suitable as information for detecting the movement of the object moving immediately above. However, in the present invention, the object detection is not performed with one antenna, the unique identification number of the antenna and the satellite number in which the signal has changed in the antenna are output from the single antenna, and the information integration unit receives information from the plurality of antennas. Since the object is detected by performing the discrimination together, it is possible to use the information of the satellite having a low elevation angle, which has been ignored in the prior art. Next, the flow of detecting the presence of an object between two antennas using two antennas will be described. In the aircraft Air in the figure, the satellite Ea being detected by the antenna A1 and the satellite Ef being detected by the antenna A2 are blocked. The information integration unit 5 detects the presence of an object between the two antennas based on the direction of the blocked satellite transmitted from each antenna and the position of the antenna.
[0012]
FIG. 4 is a diagram illustrating a flow of detection of a horizontal plane with respect to the ground in an embodiment in which an aircraft is a detection target. As the aircraft Air moves in the direction X1, the reception intensity of the signals Ea to Ef from the GPS satellites being received by the antennas A1 to A4 is changed. The received signal Ef of the antenna A1, then the signal Ee of the antenna A3, then the signals Eb and Ec of the antenna A4, and then the signal Ea of the antenna A2 are affected, and the information is received from the antennas A1 to A4. It is sent to the integration unit 5. The flow for detecting the presence of the aircraft Air at the position in the figure will be described with reference to FIGS.
[0013]
FIG. 5 shows a time chart in which signals from the satellites received by the antennas A1 to A4 in FIG. 4 change as the aircraft Air passes. Here, (1) represents the reception state of the satellite Ef of the antenna A1, and indicates that the intensity has decreased from H to L at time t1. (2) shows the reception state of the satellite Ee of the antenna A2, (3) shows the Eb of A4, (4) shows the Ec of A4, and (5) shows the reception state of Ea of A2. Here, when the reception intensity of the three antennas A1, A3, A4 changes during the time interval T obtained by experiment, the position of A1, A3, A4 and the elevation angle and direction with respect to the satellite are used to determine the aircraft Air shown in FIG. The range in which is present is calculated.
[0014]
FIG. 6 shows a procedure for calculating the position range of the aircraft Air based on the information (1), (2), and (3) shown in FIG. When the satellites of the antennas (1), (2), and (3) in FIG. 5 fluctuate during time T, antenna numbers are transmitted from the antennas A1, A3, and A4 in FIG. 6 to the information integration unit. The information integration unit calculates that the aircraft Air has passed through the area inside the triangle surrounded by the antennas A1, A3, A4 from the coordinates of the known antennas A1, A3, A4. In this case, since only the number of the antenna whose signal has changed needs to be transmitted to the information integration unit 7 from the antenna side, the amount of information transmission is the smallest. As an example of the antenna information sent from the antenna, not the antenna number but the antenna coordinate position information or the like may be sent.
[0015]
FIG. 7 shows the processing procedure in the zone orientation information integration unit 7 shown in FIG. From the information sent from the antennas A1 to An, it is detected that there are three antennas whose reception intensity has changed within the time T. It is determined that an object exists in the triangle surrounded by the three antennas. The object position range is calculated from the three antenna coordinates and output.
[0016]
FIG. 8 shows a procedure for calculating the position range of the aircraft Air based on the information of (1), (2), and (3) shown in FIG. 5 by a method different from FIG. When the satellites of the antennas (1), (2), and (3) in FIG. 5 fluctuate during the time T, the antenna numbers and signals change from the antennas A1, A3, and A4 in FIG. Send the number of the satellite that was. In the information integration unit, from the coordinates of the known antennas A1, A3, and A4 and the GPS satellite orbit information of each number held in the information integration unit itself, the aircraft Air orbits the signal Ef with respect to the antenna A1, the Ee orbit with respect to A3, It is calculated that a region inside the triangle surrounded by the Eb trajectory with respect to A4 is passed. In this case, it is necessary to transmit the antenna number and satellite number whose signal has changed from the antenna side to the information integration unit 8 and the amount of information transmission is larger than the method of FIG. Since it can be limited to a narrower range than the method of FIG. 6, the accuracy is high.
[0017]
FIG. 9 shows a processing procedure in the information integration unit 8 of zone orientation shown in FIG. From the information sent from the antennas A1 to An, it is detected that there are three antennas whose reception intensity has changed within the time T. It is determined that an object exists in the vicinity of a triangle formed by the direction of each blocked satellite of the three antennas. The position range of the object is calculated from the coordinates of the three antennas and the direction of the satellite, and is output to the display device.
[0018]
FIG. 10 shows the effective detection range of one object antenna. The prior art only describes that satellites with a low elevation angle are ignored, and no specific numerical values are given. Here, if the lower limit value of the elevation angle of the satellite is α, the effective radius r at which an object having a height h in FIG. 10 can be detected when the object comes in the direction X1 with respect to the antenna A1 is r = h ÷ tan α Become. Here, if the height of the object is 5 m and the minimum elevation angle of the satellite is 45 °, then r = 5 m and the diameter is 10 m. Since the conventional method is a method that detects only the presence of an object with one antenna, the accuracy with respect to the position decreases as the effective radius is increased, and it can be seen that the accuracy is considerably lowered even when 45 ° is the minimum elevation angle.
[0019]
FIG. 11 shows the distance Ta between the antennas required when a plurality of antennas (A1 to A4) are installed in order to continuously detect the movement of the object in the conventional object detection when the object detection effective radius is r. FIG. Here, only the height h of the object is considered, and the length of the component parallel to the ground surface of the object is ignored. When the effective detection radius per antenna is r, the distance between the antennas is Ta = 2r × cos 45 °. If the conventional technique is α = 60 ° and the height of the object is 5 m, the conventional technique has an effective detection radius r = 2.9 m and an antenna distance Ta = 4.1 m.
[0020]
FIG. 12 is a diagram showing the distance between antennas for object detection using two or more antennas as an example of the embodiment of the present invention when the object detection effective radius is r. In this case, the object detection between the antennas is detected by two or more antennas by setting the distance between adjacent antennas to the effective detection range. Here, if the height of the detection object is 5 m and the elevation angle is α = 20 °, the present embodiment has an effective detection radius r = 13.7 m and an antenna distance Ta = 13.7 m. According to this calculation, it can be detected that four antennas can be detected in the present embodiment compared to a space that conventionally requires 16 antennas, and the number of installed antennas can be greatly reduced. Here, the effective detection radius r in the object detection method using two antennas of this embodiment is based on the premise that a plurality of antennas are arranged as shown in FIG. 12, and the number of satellites that can be supplemented is limited. Therefore, it is necessary to set the effective detection radius smaller than the above theoretical value, and details are obtained by experiment.
[0021]
FIG. 13 is a diagram showing the distance between antennas for object detection using three antennas as an example of the embodiment of the present invention. In the detection by one antenna, the detection position accuracy deteriorates when the detection effective radius is increased. However, in the present invention, since detection is performed using three antennas, the object detection position accuracy is not affected even if the distance between the antennas is increased. By detecting with three antennas, an artificial satellite with a low elevation angle can be used, so that the effective detection radius can be increased. Theoretically, the distance between antennas is infinite, but in practice, it is necessary to set it in consideration of the number of satellites that can be captured.
[0022]
In the above embodiment, only the position range of the aircraft movement has been specified. However, the information integration unit holds the shape and characteristics of the aircraft in advance, and collates with the result of integrating the orbits of multiple satellites detected through the object. This makes it possible to determine the type of aircraft. Examples of the artificial satellite include GPS (Global Positioning System), NNSS (Navy Navigation Satellite System), and the like.
[0023]
【The invention's effect】
As described above, according to the present invention, it is possible to increase the installation interval of the GPS receiving antennas, and the number of installations can be reduced, so that the position of the object can be specified at low cost.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an object detection system as an example of an embodiment of the present invention.
FIG. 2 is a diagram schematically showing a relationship between a GPS satellite and a receiver.
FIG. 3 is a configuration diagram of a plane perpendicular to the ground surface for object detection of an aircraft as an example of an embodiment of the present invention.
FIG. 4 is a configuration diagram of a horizontal plane with respect to the ground surface for object detection of an aircraft as an example of an embodiment of the present invention.
FIG. 5 shows a time chart in FIG. 4;
FIG. 6 is a diagram showing a method for specifying a position range in zone determination of an aircraft as an example of an embodiment of the present invention.
7 is a diagram showing a flow of processing in the information integration unit when the position range specifying method of FIG. 6 is used. FIG.
FIG. 8 is a diagram showing a method for specifying a position range by a method different from that in FIG. 6 in aircraft zone location according to an embodiment of the present invention.
FIG. 9 is a diagram showing a flow of processing in the information integration unit when the position range specifying method of FIG. 8 is used.
FIG. 10 is a diagram showing an object detection effective radius per antenna according to the related art and the embodiment of the present invention.
FIG. 11 is a diagram showing a distance between antennas for object detection using a conventional antenna.
FIG. 12 is a diagram illustrating an inter-antenna distance for object detection using two or more antennas.
FIG. 13 is a diagram illustrating an inter-antenna distance for object detection using three or more antennas.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Reception antenna, 2 ... Signal processing apparatus, 3 ... Information transmission apparatus, 4 ... Transmission path, 5, 7, 8 ... Information integration part, 6 ... Result display part.

Claims (2)

Information for detecting a plurality of antenna for receiving a radio wave transmitted from a satellite, a signal processing apparatus for processing a signal received by the antenna, the position range of the object based on the signal output from said signal processing device An object detection system including an integration unit, wherein the plurality of antennas include a first antenna and a second antenna, and the information integration unit is an artificial satellite whose reception intensity has changed with the first antenna. And the first azimuth information is obtained as the azimuth of the artificial satellite, the artificial satellite whose reception intensity is changed by the second antenna is identified, and the second azimuth information is obtained as the azimuth of the artificial satellite. An object detection system configured to detect a position range of an object based on both the first azimuth information and the second azimuth information . In an object detection method for receiving a radio wave transmitted from an artificial satellite and detecting a position range of the object based on the received signal, an artificial satellite whose reception intensity has changed with a first antenna is identified, and the artificial satellite The first direction information is obtained as the azimuth, the artificial satellite whose reception intensity has changed by the second antenna is specified, the second azimuth information is obtained as the direction of the artificial satellite, the first azimuth information and An object detection method for detecting a position range of an object based on both pieces of information of the second orientation information .

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