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Description  |
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FIELD OF THE INVENTION
This invention relates generally to the field of location-position systems, methods and apparatuses and, in particular embodiments, to relay assisted location-position systems, methods and apparatuses which employ the use of Radio Frequency (RF)
tags and data relays.
DESCRIPTION OF THE RELATED ART
Location position (LP) systems ascertain positions of particular objects and/or track the locations of objects. Historically, location position systems have been quite diverse. Some location position (LP) systems and processes have typically
employed sensor devices, such as motion sensors, heat sensors, or the like, for detecting the presence of an object or personnel to be located or tracked. Other LP systems have employed labels or tag elements, such as, for example, bar codes, RF labels,
short-range RF tags, long-range RF tags, and the Global Positioning System (GPS) which provide a signal that has location information or is indicative of location by virtue of its transmission.
A simplistic example of a military application utilizing a rudimentary position system is the proximity sensor used in anti-personnel landmines. An anti-personnel mine is basically a proximity sensor coupled to an explosive charge. An
anti-personnel landmine is one that detects the presence of a target, for example an enemy soldier, and in response, initiates an explosive charge within the proximity of the detected enemy. Such anti-personnel landmines typically detect whether a
target is present or absent from a designated area (i.e. in a local position), but do not track or ascertain actual locations.
Anti-personnel land mines have several disadvantages as a military position detection system. A first disadvantage is that the activation of one anti-personnel landmine provides a warning to any enemy of the possible presence of other landmines. A first anti-personnel landmine detonation may provide an element of surprise, but once a first anti-personnel landmine has detonated, any other enemy target within the area will be alerted to the possible presence of other anti-personnel landmines.
A second drawback of typical anti-personnel landmines is that it does not discriminate between friend and foe. Friendly forces wandering into an anti-personnel landmine area may be destroyed by such mines. Such anti-personnel landmines are also
a threat to friendly forces, during deployment. For example, a mine may be accidentally activated or may be activated by the initiation of hostilities before the placement of the mine can be complete. Typical anti-personnel landmines also are
nondiscriminatory. That is, they may be detonated by nonmilitary personnel in the area, or remain deployed and active well after hostilities cease.
In some commercial applications, a LP system comprises machine readable labels or tags have been placed on products or items for inventory control and tracking. In other commercial applications, RF transmitting tags have been affixed to, for
example, personnel, vehicles, or other objects to monitor or track the position of such vehicles.
A variety of commercial type location-position systems are available from various manufacturers. One example of commercial (LP) systems is the Tiris.TM. system from Texas Instruments. A typical Tiris.TM. system could illustratively comprise a
Tiris.TM. transponder and a RFID (radio frequency identification tag) that can be attached or embedded within objects. A Tiris.TM. unit sends a radio frequency signal to the tag and the tag broadcasts its stored data back to the Tiris.TM. unit. The
data broadcast back to the Tiris.TM. unit includes a unique 20-digit code that identifies the RFID tag to the Tiris.TM. unit. Such a system provides an identification of an RF tag in close proximity to a Tiris.TM. reader. It, however, provides no
location information. Although the Tiris.TM. system can identify an RF tag, it cannot track it.
Other commercial systems provide tracking capability. One such commercial system that provides tracking capability is provided by PinPoint Corporation of Billerica, Mass. PinPoint provides a product called a 3D-iD.TM. location position system. The PinPoint system comprises three basic building blocks: RF tags, cell controllers and software. The 3D-iD.TM. tags can be attached the item desired to be tracked. The tag receives 2.4 ghz spreads spectrum signals from the 3D-iD.TM. system antennas
and responds with a 5.8 ghz signal which includes data uniquely identifying the tag. Tags can be read at ranges up to 200 feet and hundreds of tags can be read by a single cell controller.
The 3D-iD.TM. cell controllers coordinate exchange of data between antennas and the tags. The cell controllers communicate with the tags via a 2.4 GHz radio signal. The controllers then receive a re-transmitted signal and calculate the time
delay between the originally transmitted 2.5 GHz signal and the return 5.8 GHz signal. By receiving the return signal from the tags with several antennas and noting the difference in the time delay the exact identity and location of the tags can be
determined.
The PinPoint system also comprises viewpoint software which allows a user to display the information gathered by the PinPoint system. The PinPoint system can offer both identity and location information in range.
While various military and commercial location or tracking systems have been developed, many systems tend to require relatively large and/or expensive tags disposed on the objects or personnel to be located or tracked. Other systems employ
relatively unsophisticated detecting or sensing devices such as proximity sensors that do not sufficiently discriminate between intended targets and non-target objects or personnel. Proximity sensors can detect only presence but cannot tell if friend or
foe has been detected. As such, the practical application of such systems has been limited.
Military systems have also employed methods such as automatic target recognition (ATR). Automatic target recognition employs signal processing methods which attempt to recognize sound signatures of targets. By processing the sound emitted by
various targets, frequency and amplitude relationships can be identified that can be used to distinguish various targets. In addition, by applying multiple sensors and directional principals a target can be located.
While automatic target recognition can be effective, environmental factors such as wind, rain, and noise can interfere with ATR and render it inaccurate.
SUMMARY OF DISCLOSURE
To address limitations in the prior art described above, and to address other limitations that will become apparent upon reading and understanding the present specification, an RF tag and tracking system, comprises a plurality of tags
(preferably, low-power, radio frequency (RF) identification tags), and a base station and intermediate tracking relays is disclosed. In certain embodiments of the present invention, intermediate relays provide single or multi level links between
low-powered RF tags and the tracking base station.
According to one embodiment of the invention, each tag is provided with processing circuitry for determining the location position of the tag. According to another exemplary embodiment, position determining computations or functions are instead
performed in intermediate relay nodes, which serve as intermediate units between the tags and the positioning base station. In yet a further exemplary embodiment, position determination functions are centralized in a base station, thereby relieving the
tags and the intermediate relays of the burden of location position determination.
According to further embodiments of the present invention, tags are automatically activated by a trigger mechanism, for example, upon deployment of the tags. Such a trigger mechanism may also load information corresponding to an initial position
into tags, for example, from a GPS signal produced within a deploying mechanism. The tag position can then be tracked by an internal navigation system within the tag.
Further embodiments of a system in accordance with the principles of the invention may include additional aspects and alternate implementations. One such aspect relates to the employment of various networking technologies to extend the tracking
range of the tags, as well as providing for robust communications. For example, to address a situation in which a number of relays are destroyed or otherwise not functioning. Relays provide multiple paths for conveying information from the tags to a
base station.
Embodiments of the present invention include features that simplify the transmit control. Because the tags transmit asynchronously they do not need a receive function to coordinate transmission between tags. Without a receive function, RF
transmissions from the tags cannot be disrupted by an interruption of synchronizing information, because the tags do not accept synchronizing information. In addition, dispensing with the need to synchronize transmissions simplifies control within the
tags. The tags transmit at pseudo-random periods instead of continuously. Pseudo-random transmit periods may be determined by pseudo-random number generators within each tag. The pseudo-random number generators may have a built-in seed number, for
example, implanted during manufacture, to generate pseudo-random numbers or may generate pseudo-random numbers using pre-assigned tag identification numbers, serial numbers, or the like. In addition to providing communications with low probability of
exploitation (LPE) by transmitting at pseudo-random times thereby making it more difficult for an enemy to lock on to transmissions, the tags are able to conserve energy by not transmitting in a continuous mode. Because the tags transmit sporadically,
power can be conserved by power cycling parts of the circuitry within the tag when they are not being used. Additionally, the sporadic transmission allows more tag transmissions with reduced transmission collision at the relays or base stations.
Additional tag transmissions can be accommodated by increasing the mean time between transmissions from the tags. The mean time between transmissions can be increased by changing the software which generates the pseudo random transmit periods.
Tags can also be tailored for specific applications, for example, tag transmissions can incorporate information in addition to an identifier. For example, in warehousing applications the tag may incorporate a list of items stored within a
container. A tag then would not only give the position of the container, but also a list of its contents.
These and other advantages and features of embodiments of the invention will be apparent to those skilled in the art from the following detailed description of preferred embodiments, when read with the drawings and appended claims.
BRIEF
DESCRIPTIONS OF THE DRAWINGS
Referring to the accompanying drawings in which like reference numbers represent corresponding parts in all the drawings.
FIG. 1 is a generalized graphical representation of a location position (LP) system according to an embodiment of the present invention.
FIG. 1A is a generalized graphical representation of an alternate location position system according to a further embodiment of the present invention.
FIG. 2A is a generalized graphical representation of a location position (LP) system with distributed Time Delay Of Arrival (TDOA), according to an embodiment of the present invention.
FIG. 2B is a block diagram of an example Radio Frequency (RF) tag as may be used with the embodiment illustrated in FIG. 2A.
FIG. 2C is a generalized cross-sectional representation of an example tag dispenser as may be used with the embodiment illustrated in FIG. 2A.
FIG. 2D is a generalized block diagram of an example relay as may be used with the embodiment illustrated in FIG. 2A.
FIG. 2E is a generalized block diagram of an example base station as may be used with the embodiment illustrated in FIG. 2A.
FIG. 3A is a generalized graphical representation of a location position (LP) system with centralized Time Delay Of Arrival (TDOA), according to an embodiment of the present invention.
FIG. 3B is a generalized block diagram of an example relay, as may be used with the embodiment illustrated in FIG. 3A.
FIG. 4A is a generalized graphical representation of a direct Inertial Navigation System (INS), according to an embodiment of the present invention.
FIG. 4B is a generalized schematic illustration of the components of an exemplary Inertial Navigation System (INS).
FIG. 4C is a generalized block diagram of an example tag as may be used with the embodiment of the invention illustrated in FIG. 4A.
FIG. 4D is a generalized graphical illustration of an example dispenser as may be used with the embodiment of the invention illustrated in FIG. 4A.
FIG. 4E is a generalized block diagram of an example relay as may be used with the embodiment of the invention illustrated in FIG. 4A.
FIG. 5A is a generalized graphical illustration of a networked Inertial Navigation System (INS) embodiment of the invention.
FIG. 5B is a generalized block diagram of a relay as may be used with the embodiment of the invention illustrated in FIG. 5A.
FIG. 6 is a generalized block diagram of an alternate embodiment of a tag, as may be used with an embodiment of the invention wherein the tag determines its own position.
FIG. 7 is a generalized graphical illustration of a multipath problem addressed by embodiments of the present invention.
FIG. 8A is a generalized block diagram of a digital binary phase shift keying transmitter with digital in phase and quadrature spreading codes, as may be used within an RF tag according to embodiments of the invention.
FIG. 8B is a generalized block diagram of a digital direct transmitter with a digital spreading code as may be used in RF tags according to further embodiments of the invention.
FIG. 9 is a generalized schematic diagram of a relay receiver, according to a further embodiment of the invention.
FIG. 10 is a generalized block diagram of multi-user discriminator as may be used with embodiments of the invention.
FIG. 11A is a graphic diagram of a composite signal made up of a desired signal and an interfering signal.
FIG. 11B is a graphic diagram of a composite signal made up of a desired signal and an interfering signal where an interfering signal is present before the arrival of a desired signal.
FIG. 12A is a generalized schematic diagram of a power system as may be used within RF tags in embodiments of the present invention.
FIG. 12B is a generalized schematic diagram of a rechargeable power system for an RF tag as may be used with embodiments of the invention.
FIG. 13 is a generalized graphical illustration of a system embodiment showing the use of relays with varying range capabilities.
FIG. 14 illustrates the bootstrapping method.
FIG. 15 illustrates relay position determination using three other relays.
DETAILED DESCRIPTION OF THE INVENTION
In the following description of preferred embodiments, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration a specific embodiment in which the invention may be practiced. It is to
be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the preferred embodiments of the present invention.
Overview
The present invention relates, generally, to location position systems, methods and apparatuses, for locating and/or tracking objects or entities. As will become apparent from the description herein, embodiments of the invention may be employed
in a variety of different applications, including various military, industrial and commercial applications. For example, location position systems and methods according to embodiments of the present invention may be used in applications relating to
locating and/or tracking inventory, including, but not limited to, inventories of goods, supplies, components used in manufacturing, or manufactured products. Such systems and methods may be employed to locate or track luggage, for example, in an
airport or bus or train station, or to locate or track postal or courier packages, or the like.
Location position systems and methods according to further embodiments of the present invention may be used in applications relating to locating and/or tracking personnel, including, but not limited to hospital or business staff, patients,
security personnel, children, prison inmates, unauthorized boarder crossers or other individuals or groups. Such systems and methods may also be used for tracking destructive animal pests, animals in zoos, game reserves, parks, or the like.
Location position systems and methods according to embodiments of the present invention have a variety of military applications as well, including, but not limited to, locating or tracking friendly or enemy troops or equipment. In applications
related to locating and tracking enemy troops or equipment, such systems and methods may employ location or tracking information to control or direct smart weapons, such as mortars, missiles, bombs or other projectile, or even stationary weapons such as
mines, to target the enemy troops or equipment. Representative examples of military and commercial applications are described below to assist in the disclosure of various aspects of the invention. However, it will be understood that aspects of the
invention are not limited to the specific representative example embodiments and applications described herein, as many additional applications and subsystems may be devised utilizing the teachings of this disclosure.
Location position systems and methods according to preferred embodiments of the present invention employ RF tags that are associated with objects or entities to be located and/or tracked, for example, by being affixed to each object or entity to
be located and/or tracked. Alternately, tags can be programmed with information as or before they are attached to objects. As described in more detail below, each tag is preferably provided with a transmitter for transmitting a location identification
signal. In certain embodiments, a relay device is located within the transmission range of each tag, for receiving tag transmissions and relaying signals to a base station for further processing.
In preferred embodiments, the tags are designed to be relatively small and inexpensive, for example, so as to be inconspicuous and disposable. In such embodiments, the electronics associated with such tags are configured to be relatively simple
and require minimal power.
The tags may be associated with the objects or entities to be located in a variety of manners, including manual or automated placement of a respective tag on each object or entity to be located or tracked. For example, each tag may be affixed to
a respective object or its container, imbedded in the object, placed next to the object, or otherwise associated with the location of the object. In the context of personnel location or tracking, the tags may be, for example, affixed to badges,
identification cards, or articles of clothing or other items worn or carried by the personnel to be located or tracked. In some embodiments, tags may be surgically implanted on personnel.
According to other embodiments, the tags are deployed in an area in which an object or entity to be tracked or located may or will be passing. In the context of an manufacturing or inventory application, the tags may be manually or automatically
dispensed and associated with objects, such as products, supplies, components or the like, as the objects (or containers containing the objects) are conveyed past a pre-designated location, such as a tagging station along a conveyor path of a production
line. If only the general area in which objects or entities may or will pass is known, then tags designed to affix (or otherwise associate) themselves with passing objects or entities may be dispersed throughout the general area. Such a tag may then be
affixed (or otherwise associated) with an object or entity that happen to pass through the general area and which comes within sufficiently close proximity to the tag to allow the tag to affix (or otherwise associate) itself with the passing object or
entity.
As noted above, tags may simply be manually deployed and associated with each object or entity to be located or tracked. However, in preferred embodiments, tags are dispensed by an automated or manually controlled dispensing apparatus. In the
production line embodiment, an automatic dispensing apparatus may comprise a device located along the conveyor path of the production line, for dispensing and affixing (or otherwise associating) a tag with each product or component passing the dispensing
apparatus on the conveyor path. In embodiments in which tags are to be dispersed within a given general area (for example, a general area in which one or more objects or entities may or will pass), a dispensing apparatus may comprise a device for
distributing tags randomly, partially randomly, or even at specific locations within the general area.
For purposes of simplifying the present disclosure, representative example embodiments of the present invention are described, with reference to a military context, in which objects or entities to be located and/or tracked are enemy troops or
vehicles which are expected to pass through a general area. However, as noted above, it will be understood that various aspects of the invention are not limited to such military embodiments and may, for example, be employed in various commercial or
industrial contexts, such as described above.
A position location system according to an embodiment of the present invention, as shown in FIG. 1, includes a plurality of tags 201, a tag dispenser device 203, one or more relays 205 and at least one base station 207. The base station 207 is a
device for accepting information from relays. A base station need not be a stationary device and may comprise a variety of configurations such as, for instance, laptop computers or PDA's. The tags 201 include transmitting devices which transmit
signals, for example, upon the tag being dispensed by the dispenser 203. In one preferred embodiment, each tag 201 includes a radio frequency (RF) transmitter which transmits signals containing identification information, such as an unique
identification code.
The relays 205 include receivers located within the transmission range of tags in the area 204. Each given relay 205 need not be positioned within the transmission range of all of the tags in the area 204. However, it may be preferred that the
group of relays 205, as a whole, are positioned to receive transmissions from all tags within the area 204 so as to provide the maximum number of paths for transmissions from any tag to a base station. Another reason it may be preferred that the group
of relays 205 be positioned within the transmission range of all the tags in the area is that in the case where the relays perform positioning functions, such as time delay measurements or triangulation measurements on the relays, a greater number of
measurements can yield a greater number of data points and thereby enhance accuracy.
The tags 201 are shown in FIG. 1 as having been dispensed by the dispenser 203 and are distributed within a general area 204. The dispenser 203 may comprise an active dispensing device which actively places or propels tags throughout the general
area 204. In one example, the dispensing device dispenses tags by activating an explosive charge, pneumatic impulse or other propelling means, which propels tags throughout the area 204. The explosive charge (or other propelling means) may be
activated, for example, by a proximity sensor designed to detect an enemy soldier, vehicle or the like within a certain proximity of the sensor. The proximity sensor may be located within the tag dispenser 203 or, alternatively, at other locations
remote from the dispenser, such as at an entry path leading to the general area 204. Such a proximity sensor may include, but is not limited to, a vibration sensor, contact sensor, heat sensor, metal detector, combinations thereof or other suitable
sensing or detecting means. In further embodiments, the explosive charge (or other propelling means) may be activated by a signal transmitted from a remote location, a timing signal provided at a preset time, or the like. Alternatively, the dispenser
device 203 may comprise a passive dispenser designed to dispense tags passively, for example, by adhering the tag to an enemy soldier or vehicle as the enemy soldier or vehicle brushes against or passes adjacent the dispenser.
In the above embodiments, tags 201 may include (or be dispensed with) an adhesive material, attaching hooks, magnetized material or other suitable means for attaching the tags to passing soldiers or vehicles. In one preferred embodiment, tags
201 distributed within the area 204 by a propellant, as described above, attach to soldiers or vehicles which are present in the area 204 at the time of disbursement or, alternatively, adhere to soldiers or vehicl | | |
