Patent Application
20200342188
Prior art methods of locating animals in a cage include implanting an radio frequency identification device (RFID), a transponder, in an animal, then using a transceiver to query the RFID, then receiving back a transponder signal from the transponder to the transceiver. The transponder signal typically comprises a unique device identifier and may include other information such as a temperature of an animal. The RF communication distance between the transponder and the transceiver is typically a short distance, such as a few inches. If an animal is in range of the transceiver, it is “detected.” If an animal is not in range then it is, “not detected.” A weakness of this system is it provides only information when an animal is in RF proximity to the transceiver.
Other prior art uses multiple transceivers, in order to provide information when an animal is in one of the proximal locations to the multiple transceivers. A weakness of this system is that the transceiver signals may interfere with each other, and thus must be spaced widely. This spacing leaves gaps in the coverage area.
Commercial prior art transceivers have integrated transmit and receive logic. They do not communicate with each other and thus cannot transmit simultaneously.
Prior art includes Standards ISO 11785-1996 and ISO 18000. It also includes U.S. Pat. No. 7,049,933 and Chinese Patent No. CN103116734.
Embodiments of this invention overcome the weaknesses of prior art. An array of transceivers is used to detect transponders in animals. To avoid interference between the transceivers, they all transmit simultaneously. These transmissions are known as “queries” to any transponders within radio frequency (RF) range. The transmit power of the transponders is much weaker than the transmit power of the transceivers. Some transponders have no transmit power at all, as they change a “visible” characteristic, such as an RF resonance. However, we still speak of a transponder as “sending” a signal comprising data. Only a transponder that is close to a transceiver will properly receive its signal. The purpose of the map is to identify physical locations of the animals in the cage corresponding to locations of transceivers.
Spacing of the transceivers is important. A planar grid of transceivers may be under or over a cage. In additional transceivers may be placed on the sides of the cage, near to exercise, sleeping, eating or drinking apparatuses. These transceivers will pick up an animal location when the animal is using one of these apparatuses. Such apparatuses may be raised above a cage floor such that they are effectively out of near-field RF range of transceivers located under the cage floor.
It is important that all transceivers transmit signals simultaneously. Such signals may comprise data, such as a “query,” or may comprise a continuous RF carrier. In this way they do not interfere with each other, but rather create a uniform RF query field in the cage. Transponders each respond timely to a query, or reply periodically to an RF carrier. However, they do not respond synchronously; rather each transponder provides its own data timely, but not synchronized. Each transceiver needs separate, independent receive logic.
Scenarios, descriptions, drawings and options are non-limiting embodiments.
As explained above, a nexus of embodiments is having a group of transceivers broadcast synchronously, while each transceiver separately receives data from individual transponders. In one embodiment a “query” signal is broadcast, then transceivers listen. In another embodiment, transceivers phase-synchronously broadcast a continuous carrier signal, while each transceiver listens independently for changes in signal amplitude caused by a nearby transducer.
For some types of standardized RFIDs and embodiments, communication works as follows. A transmitter, called a transceiver, broadcasts an unmodulated RF signal, reasonably called a carrier. The carrier may be broadcast continuously or intermittently. The transceiver contains a circuit resonant at the RF carrier frequency. The circuit typically includes a coil with an inductance and a capacitor. This combination is sometimes called a, “tank.” As the tank resonates at the carrier frequency the coil acts as a broadcast antenna creating a “near-field.”
RFIDs, in this near-field, called transponders, also have a resonant tank circuit at the carrier frequency. Because the distance between the transceiver and transponder is short compared to the wavelength of the carrier, both the transceiver tank and the transponder tank share the same near-field electromagnetic radiation: they resonate together. Typically, the transponders receive the broadcast carrier, rectify it, and use that as an internal power source. The transponder electronics have the ability to short out or otherwise modify the resonance of its tank. When so shorted, the total amplitude of the carrier signal within the near-field weakens. This weakened field strength may be detected at the transceiver, typically as slightly lower voltage amplitude at the tank. In this way, the transponders are able to effectively send data to the transceivers, by alternatively turning on and off its tank shorting circuit, in some time pattern.
For one transceiver and one transponder in the same near-field, this system works well enough. It is a simple matter to detect if a transponder is in proximity, that is, in the same near-field as the transceiver, because the transceiver then detects some data from the transponder. However, receiving signals, or detecting the presence of multiple transponders in the same near-field is challenging because the transponders interfere with each other. Placing multiple transceivers in a physical arrangement, such as a grid, to detect multiple transponders, is challenging because the multiple transceivers also share a near-field and thus also interfere with each other.
A solution of one embodiment is to use an array of multiple transceivers operating synchronously to create a single, shared near-field. The effect of any transponder in the near-field is quite small, and is most detectable close to its nearest transponder.
The spacing of the transceivers is important. If they are too far apart, then special resolution is lost. For example, if there are four transceivers under a cage floor, there is an effective distance resolution to one quarter of the cage. If there are 40 transceivers under a cage floor, there is potentially an effective resolution of forty areas within the cage. However, if the transceivers are too close together, a single transponder will affect the signal strength at the two adjacent transceivers approximately equally, and they will not be able to distinguish one location of the transponder from another. Additionally, the broadcast signal strength at each transceiver will swamp the small change in signal strength at an adjacent transceiver, making neither able to detect a signal strength change caused by a nearby transponder. Therefore, spacing of transceivers must be carefully chosen to balance these factors.
In a simple model, the transceivers should be spaced as close together as possible (to maximize special resolution) while still being able to detect transponders. This distance could be determined experimentally for any particular set of devices, in an appropriate environment. Note that a, “received signal strength” is really a detection of signal amplitude change at a transceiver due to the presence or absence of a non-shorted transponder tank. This might be on the order of a few tens of millivolts on a signal of 100 volts, as measured at the transceiver tank. “Noise,” in this environment, is variation in the signal strength at the transceiver tank from all other sources. The minimum spacing of two transceivers is such that each is able to reliably receive data from a transponder at a selected target distance. “Reliable,” in this context, may be a predetermined signal-to-noise ratio or a percent of validly received transponder messages. For transceivers in a two-dimensional grid, the definitions and requirements are similar. A “target distance” may be a typical distance from a transponder to a transceiver. For example, if an array of transceivers is under a cage floor, and transponders are implanted between the shoulders of rodents in the cage, a target distance may be the typical or average vertical distance normal from the transceiver array plane to the transponders when the rodent is moving about the cage. References to a target distance, in some embodiments, also include any distance less than the target distance. A suitable reliable read rate might be 100 percent, or 100 percent minus specialized exceptions that do not diminish the value or use of the invention as a whole, or greater than 90 percent, or greater than 50 percent, as examples, as a rodent moves typically about its cage. A “read rate” and a “signal-to-noise” have a close relationship, and typically either one may be used to determine acceptable transceiver spacing, for a given environment and circuitry. With respect to claim construction and the rule of equivalents, they may be considered functionally equivalent. A successful read by an array of transceivers is when any transceiver in the array receives a valid transponder message. Note that such testing or measurement is typically done with only a single transponder, such as a single animal in a cage, as two transponders sufficiently close to each other may also cause a non-read. For two or more animals in a cage, typically the total valid read rate will therefore be less than the valid rate if there is only a single animal in the same cage.
A desired transceiver spacing is such that a read rate is at least a predetermined reliability at a selected target distance.
For cages with apparatuses, such as climbing structures, exercise wheels, and the like, design and interpretation is similar, suitably taking into account that spacing may now include also spacing inward, i.e., horizontally, from the sides of a cage.
Reply signals from RFID transponders are in response to the RF transmissions from transceivers.
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It is worth noting three logical levels of, “at the same time.” At the top level is, “logically at the same time,” which means on a human time scale of seconds, devices operate similarly. At the next, second, level, “signaling,” on a time scale of milliseconds, devices may be told to broadcast. For example, a control line to an integrated circuit (IC) may be to, “start transmitting.” Such a signal might be a binary control line or a command over a serial bus such as an ASCII RS-232 serial port, or an SDI or I2C bus. At the lowest, third, level, “RF modulation,” the RF carrier wave and its modulation are synchronous. All transceivers work effectively as a distributed antenna broadcasting the same RF signal. It is in this last mode that the transceivers are driven for broadcasts, that is, queries or requests. Thus, their RF signals do not interfere, but rather blanket a cage with a single RF signal, a “query” or “request,” needed to trigger a response from transponders. The signal 35 in
In the prior art, with integrated IC transceivers, only the top two levels discussed above, are available.
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Each animal 11 and 12 typically has an implanted RFID transponder, not shown. Transponders may alternatively be placed on ear tags or collars. RFID transponders may also be used on (human) ankle bracelets. Each RFID has a unique identifier, which we call a serial number, which in turn allows animals to be uniquely identified.
Associated with the mechanical arrangement of the eight transceivers shown in the cage in
Based on information collected from embodiments, a physical action may be performed, such as removing an animal from a study, removing an animal from a cage, euthanizing an animal, or applying for a drug or treatment approval, such as a new drug application to the U.S. FDA. In addition, husbandry elements, other cage elements, or medical treatments may be changed. For example, different exercise equipment may be placed in a cage, or the type of food altered, or animal treatment protocols, such as drugs, altered.
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If TRANSP #1, 23, is associated with animal 11, and the transponder is 14, in
In some cases, no signal is received from any transponder. This may indicate that the associated animal is out of range of any transceivers. The embodiment may assume that the animal is nearby the last transceiver to detect a valid transponder reply from that animal. In some cases, two transceivers may detect the same reply. For example, transceivers 15 and 16 may detect the same signal from animal 12. In such a case, the animal 12 may be assumed to be located in between the two transceivers. Alternatively, the transceiver with the stronger signal may be the one used for location determination. Embodiments include signal strength detectors in the transceivers. Embodiments also include error detection and/or error correction in transponder signals. If no signal or an invalid signal is received by a transceiver, it may be because two animals are in close proximity to each other. The may be sleeping together, having sex, or fighting.
In some embodiments, data is bidirectional. For example, transceivers may send data to any or all transponders. Data may be directed to a specific transponder by using the transponder's ID in the message. Although we refer to transmissions from transceivers to transponders requests or queries, these signals may in fact include data to transponders. RFID transmissions may be identified by protocol terms of the art, such as half duplex, “HDX,” or full duplex, “FDX.” Embodiments use protocol details as described in ISO Standard ISO 11785-1996.
Note that some embodiments use a different system than shown in
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The signal amplitude at the antenna or resonant circuit 54 is passes first through a detector 56 and then a demodulator 57, and then on to other logic, such as a controller, data acquisition, or remote electronics, not shown. The combination of the detector 56, demodulator 57, and associated circuitry may be called a receiver or receive circuit 55. Other circuits may be used to detect signal amplitude. Signal amplitude between 54 and 55 is shown schematically in
The terms, “RFID” and “transponder,” as used herein and in claims and drawings, are generally interchangeable, unless otherwise stated or clear from context. A “controller” comprises necessary logic, non-transitory data storage, computation, communication and analog circuitry to support or interface other elements or method steps in claims and descriptions. An array or grid of transceivers is construed broadly. Such an arrangement may neither have uniform spacing nor be arranged in a clear pattern. An orientation of coils in antennas in transceivers may produce a strange, non-uniform near-field strength tensor field. In addition, other objects, such as metal, may change the shape of a near-field. Therefore, exact positions of transceivers in a grid or array, planer or not, may vary in order to optimize an embodiment, design, implementation or use.
Ideal, Ideally, Optimum and Preferred—Use of the words, “ideal,” “ideally,” “optimum,” “optimum,” “should” and “preferred,” when used in the context of describing this invention, refer specifically a best mode for one or more embodiments for one or more applications of this invention. Such best modes are non-limiting, and may not be the best mode for all embodiments, applications, or implementation technologies, as one trained in the art will appreciate.
All examples are sample embodiments. In particular, the phrase “invention” should be interpreted under all conditions to mean, “an embodiment of this invention.” Examples, scenarios, and drawings are non-limiting. The only limitations of this invention are in the claims. May, Could, Option, Mode, Alternative and Feature—Use of the words, “may,” “could,” “option,” “optional,” “mode,” “alternative,” “typical,” “ideal,” and “feature,” when used in the context of describing this invention, refer specifically to various embodiments of this invention. Described benefits refer only to those embodiments that provide that benefit. All descriptions herein are non-limiting, as one trained in the art appreciates.
Embodiments of this invention explicitly include all combinations and sub-combinations of all features, elements and limitation of all claims. Embodiments of this invention explicitly include all combinations and sub-combinations of all features, elements, examples, embodiments, tables, values, ranges, and drawings in the specification and drawings. Embodiments of this invention explicitly include devices and systems to implement any combination of all methods described in the claims, specification and drawings. Embodiments of the methods of invention explicitly include all combinations of dependent method claim steps, in any functional order. Embodiments of the methods of invention explicitly include, when referencing any device claim, a substation thereof to any and all other device claims, including all combinations of elements in device claims. Claims for devices and systems may be restricted to perform only the methods of embodiments or claims.
