Target detection apparatus and system

• US 20080024352A1
• Filed: 01/26/2007
• Published: 01/31/2008
• Est. Priority Date: 01/30/2006
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Shirakawa, Kazuo
• Granted Patent: US 7,679,562 B2
• Time in Patent Office: Days
• US Class Current: 342/28
• CPC Class Codes: G01S 13/003 Bistatic radar systems; Multistatic radar systems
• CPC Class Codes: G01S 13/48 using multiple beams at emission or reception
• CPC Class Codes: G01S 13/878 Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector G01S13/874 takes precedence
• CPC Class Codes: G01S 13/886 for alarm systems alarms with electrical actuation G08B13/22
• CPC Class Codes: G01S 17/04 Systems determining the presence of a target
• CPC Class Codes: G01S 17/87 Combinations of systems using electromagnetic waves other than radio waves

Abstract

A wide monitor area can be covered by switching the connection between a plurality of sensors and a transmission/reception device using a switch device of a target detection apparatus in a time division manner. When only two target detection apparatuses are used in positioning a target, the position of a target can be identified according to the information about an area common to both angle ranges covered by the two apparatuses or the total propagation distance information from one apparatus to the other apparatus through each target.

Claims

1. A target detection apparatus, comprising:

a transmission/reception device for generating a transmission signal for detection of a target, and extracting distance information about the target from a received signal;

a plurality of sensor devices for transmitting the transmission signal to respective different angle ranges, receiving a signal reflected by the target, and transferring the received signal to the transmission/reception device; and

a switch device for switching in a time division manner a connection between the transmission/reception device and the plurality of sensors.

2. The apparatus according to claim 1, further comprising

an optical system sensor, wherein

the plurality of sensors normally perform a wide angle monitoring process, and when it is anticipated that the target intrudes to an emergency area, the optical system sensor detects the target.

3. A target detection system, comprising:

a first target detection apparatus having a plurality of sensors for transmitting a first transmission signal to respective different angle ranges and receiving a signal reflected by a target, and extracting first distance information about the target from a received signal;

a second target detection apparatus having a plurality of sensors for transmitting a second transmission signal to respective different angle ranges and receiving a signal reflected by the target, and extracting second distance information about the target from a received signal; and

a processing device for calculating a position of the target according to the first and second distance information using a condition that the position of the target is included in an area common to both a first angle range when the first target detection apparatus extracts the first distance information and a second angle range when the second target detection apparatus extracts the second distance information.

4. The system according to claim 3, wherein

the first and second target detection apparatuses are mounted in different positions around a monitor area, the plurality of sensors of the first target detection apparatus scan the respective angle ranges for each time slot assigned in a time division manner, the first target detection apparatus extracts the first distance information from a received signal in a time slot in which the common area is scanned, the plurality of sensors of the second target detection apparatus scan the respective angle ranges for each time slot assigned in a time division manner, and the second target detection apparatus extracts the second distance information from a received signal in a time slot in which the common area is scanned.

5. The system according to claim 3, wherein

the first and second target detection apparatuses are mounted at different positions around a monitor area, the monitor area is divided into a plurality of exclusive areas by the angle ranges of the plurality of sensors of the first target detection apparatus and the angle ranges of the plurality of sensors of the second target detection apparatus, the processing device compares a code of each exclusive area included in the first angle range with a code of each exclusive area included in the second angle range, and identifies the common area from a common code in both angle ranges.

6. The system according to claim 3, wherein

the first target detection apparatus further comprises:

a first transmission/reception device for generating the first transmission signal and extracting the first distance information from a received signal; and

a first switch device for switching a connection between the first transmission/reception device and the plurality of sensors in a time division manner, and the second target detection apparatus further comprises;

a second transmission/reception device for generating the second transmission signal and extracting the second distance information from a received signal; and

a second switch device for switching a connection between the second transmission/reception device and the plurality of sensors in a time division manner.

7. The system according to claim 3, further comprising

an optical system sensor, wherein

the first and second target detection apparatuses normally perform a wide angle monitoring process, and when it is anticipated that the target intrudes to an emergency area, the optical system sensor detects the target.

8. The system according to claim 3, further comprising

a laser light source for generating an optical signal by modulating laser light, and distributing the optical signal to the first and second target detection apparatuses, wherein the first and second target detection apparatuses transform using a photo-detector the optical signal to the first transmission signal and the second transmission signal respectively.

9. A target detection system, comprising:

a first target detection apparatus for transmitting a first transmission signal, receiving a signal reflected by a target, and extracting first distance information about the target from a received signal;

a second target detection apparatus for transmitting a second transmission signal, receiving a signal reflected by the target, and extracting second distance information about the target from a received signal;

a processing device for enabling the first and second target detection apparatuses to operate for a plurality of targets in a monostatic mode, acquiring first distance information from the first target detection apparatus to each target, and the second distance information from the second target detection apparatus to each target, enabling the first and second target detection apparatuses to operate in a bistatic mode in which the first target detection apparatus is a transmitter and the second target detection apparatus is a receiver, acquiring, for each target, total propagation distance information from the transmitter to the receiver through each target, and identifying positions of the plurality of targets by comparing a sum of the first distance information and the second distance information with the total propagation distance information about each target.

10. The system according to claim 9, further comprising

an optical system sensor, wherein

the first and second target detection apparatuses normally perform a wide angle monitoring process, and when it is anticipated that the target intrudes to an emergency area, the optical system sensor detects the target.

11. The system according to claim 9, further comprising

a laser light source for generating an optical signal by modulating laser light, and distributing the optical signal to the first and second target detection apparatuses, wherein the first and second target detection apparatuses transform using a photo-detector the optical signal to the first transmission signal and the second transmission signal respectively.

12. A target detection system, comprising:

a first target detection apparatus for transmitting a first transmission signal, receiving a signal reflected by a target, and extracting first distance information about the target from a received signal;

a second target detection apparatus for transmitting a second transmission signal, receiving a signal reflected by the target, and extracting second distance information about the target from a received signal; and

a processing device for enabling the first and second target detection apparatuses to operate for a plurality of targets, acquiring first distance information from the first target detection apparatus to each target, and the second distance information from the second target detection apparatus to each target, obtaining coordinates of intersections from equations of four circles having, as radii, a minimum value and a maximum value of the first distance information for the targets and a minimum value and a maximum value of the second distance information for the targets, and identifying a location range of the plurality of targets using the coordinates of the intersections.

13. The system according to claim 12, wherein

when a part of the equations of the four circles have no solutions, the processing device changes a combination of radii that specifies the equations of the part, recalculates the coordinates of the intersections, and identifies the location range of the plurality of targets using the obtained coordinates of the intersections.