Abstract:
A method of providing wireless animal confinement includes the steps of selecting a location of a transmitter assembly; attaching a receiver assembly to the animal, the receiver assembly being adapted to selectively provide a corrective stimulation to the animal; selecting a first distance between the transmitter assembly and the receiver assembly to define a first zone within which no corrective stimulation is provided to the animal by the receiver assembly; selecting a second distance between the transmitter assembly and the receiver assembly to define a second zone beyond the first zone within which the corrective stimulation is provided to the animal by the receiver assembly; and selecting a third distance between the transmitter assembly and the receiver assembly to define a third zone beyond the second zone within which the animal will receive no further corrective stimulation from the receiver assembly.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an animal confinement system, and, more particularly, to a wireless confinement system for an animal. 
     2. Description of the Related Art 
     Pet confinement systems often include a radio frequency transmitter having a wire loop for transmitting the radio frequency signal. The wire loop antenna roughly defines the boundary in which the animal is to be confined. The animal wears a receiving unit that is attached to its collar. If the animal gets within a predetermined distance of the wire loop antenna, the receiver unit detects the radio frequency signal transmitted from the loop antenna, whereupon a correcting stimulus such as an electrical shock is applied to the animal. A problem is that it is difficult and time consuming to lay the ground loop antenna. If a discontinuity in the wire loop antenna occurs, it is then necessary to locate and repair the discontinuity. Furthermore, once the wire loop antenna is laid into the ground, the boundaries of the animal&#39;s confinement area are fixed, and cannot be easily modified. 
     It is also known to use a wireless system to track a target, e.g., an article, animal or person. One such wireless system transmits an ultrasound signal to a receiver unit carried by the animal. In response to receiving the ultrasound signal, the receiver unit transmits a radio frequency signal back to the transmitter of the ultrasound signal. Since the speed of sound is known, and radio frequency signals travel practically instantaneously at the speed of light, the transmitting unit can calculate how far away from the transmitter the receiving unit is located based upon the time interval between transmitting the ultrasound signal and receiving the radio frequency signal. If that time interval exceeds a predetermined threshold, indicating that the receiving unit is further than a threshold distance away from the transmitting unit, a second radio frequency signal is transmitted from the transmitting unit to the receiving unit. Upon receiving the second radio frequency signal, the receiving unit applies a correcting stimulus to the animal. 
     In another such system, the transmitter modulates transmitted electromagnetic signals to produce and transmit non-random patterns of electromagnetic energy. The receiver receives the electromagnetic signals and compares the signal level of the received electromagnetic signals from the transmitter with a predetermined level. If the signal level of the received electromagnetic signals from the transmitter is less than the predetermined level, then an electronic indication of a loss of signal is produced. In addition, the phase of the modulation of the received electromagnetic signals from the transmitter is compared with a reference phase. If the phase of the received electromagnetic signals from the transmitter is not substantially in phase with the reference phase, then the electronic indication of a loss of phase is produced. The receiver also is capable of producing a warning stimulus to the pet and a control stimulus to the pet. When there is no electronic indication of a loss of signal and there is no electronic indication of a loss of phase, then the pet is considered to be in the containment area and there is no warning stimulus and there is no control stimulus to the pet. When there is an electronic indication of a loss of signal and there is no electronic indication of a loss of phase, then there is a warning stimulus to the pet. When there is an electronic indication of a loss of signal and there is an electronic indication of a loss of phase, then there is a control stimulus to the pet. 
     There are many problems with a wireless containment system as described above. One problem is that if the pet proceeds through the active range of the receiver/transmitter pair, the pet will continuously receive correction so long as the pet is outside the containment area or until the receiver battery has run down. Such prolonged correction of the pet without trainer intervention is ineffective, and subjects the pet to unnecessary discomfort. 
     In addition, using a phase detection circuit requires a large amount of output power from the transmitting unit to achieve a usable containment radius. Transmitting such a high signal level creates a potential radiation hazard for anyone in close, constant proximity to the transmitter. In order to obtain the required power, the transmitter must be supplied AC power from a household outlet. This limits the utility of the system in many ways: 1) the system is not portable, and 2) since the system is plugged into a wall outlet, much of the usable containment area is consumed by the house itself. In addition, the system is not weather resistant. Furthermore, at the receiver end of the system, using a phase detection scheme requires continuous operation, thus consuming the receiver battery more rapidly. Since such a system uses the absence of a signal to determine position relative to the containment zone, a failure within the transmitting or receiving circuit could potentially result in the animal receiving a corrective stimulus while inside the containment zone. Finally, such a prior system provides no means for applying corrective training stimulation from a separate handheld transmitter. 
     Therefore, what is needed in the art is a wireless animal confinement system, which: 1) efficiently uses both transmitter and receiver power to promote long battery life and low maintenance, 2) is portable and weather resistant to allow placement of the containment field in the exact area desired by the user, 3) contains built-in-test (BIT) circuitry to monitor the health of both the transmitter and receiver to prevent stimulation in the event of a failure in either unit, 4) has the capability to use a second handheld transmitter to support an independent training function and 5) does not subject the monitored animal to unnecessary discomfort due to unproductive corrective stimulation. 
     SUMMARY OF THE INVENTION 
     The present invention provides a wireless animal confinement method and system which solves one or more the listed shortcomings of the prior methods and systems. 
     In one form of the present invention, a location of a containment transmitter assembly is selected, and a receiver assembly is attached to the animal. The receiver assembly is adapted to selectively provide a corrective stimulation to the animal. The method of the invention includes the steps of selecting a first distance between the containment transmitter assembly and the receiver assembly to define a first zone within which no corrective stimulation is provided to the animal by the receiver assembly; selecting a second distance between the containment transmitter assembly and the receiver assembly to define a second zone beyond the first zone within which corrective stimulation is provided to the animal by the receiver assembly; and selecting a third distance between the containment transmitter assembly and the receiver assembly to define a third zone beyond the second zone within which the animal will receive no further corrective stimulation from the receiver assembly. 
     In another form of the invention, a location of a self contained, portable containment transmitter assembly is selected, and a receiver assembly is attached to the animal. The receiver assembly is adapted to selectively provide a corrective stimulation to the animal. The invention selects a distance between the containment transmitter assembly and the receiver assembly to define a zone within which no corrective stimulation is provided to the animal by the receiver assembly. A second zone within which the animal will receive no further corrective stimulation from the receiver assembly is defined automatically within the system. 
     In both forms of the invention described above, the receiver unit is further responsive to a training transmitter to deliver corrective stimulation when activated. This response is independent from any signal received from the containment transmitter. 
     One advantage of the invention is that it requires much less power than other types of wireless containment system allowing for longer periods between maintenance. Another advantage is that since the system can be portable and weather resistant, the containment field can be established in a more exact and useful area. 
     Another advantage of this system is the capability to independently train the animal using the same collar used by the containment system. An additional advantage of the invention is that the animal ceases receiving correction stimuli once the animal exceeds a predetermined distance from the transmitter assembly or a predetermined amount of consecutive stimulations have been applied, to thereby spare the animal from unnecessary discomfort due to unproductive corrective stimulation. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is a perspective view of one embodiment of the wireless animal confinement system of the present invention; 
     FIG. 2 is a top view of the containment transmitter assembly of FIG. 1; 
     FIGS. 3A and 3B are top views illustrating the various zones associated with the invention; 
     FIG. 4 is a schematic diagram of the containment transmitter assembly of FIG. 1; and 
     FIG. 5 is a schematic diagram of the receiver assembly of FIG.  1 . 
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrates two variants of the preferred embodiment of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings and particularly to FIG. 1, a wireless animal confinement system  10  of the present invention includes a containment transmitter assembly  12 , a training transmitter  13 , and a receiver assembly  14  shown attached to the collar of an animal  15 . The combination containment and training system is useful, for example, to curb unwanted behavior (digging, barking etc.) while the animal is within a containment zone. 
     Referring to FIGS. 1 and 2, containment transmitter assembly  12  includes a transmitter device  16  having a solar unit  18  and being mounted on a substantially vertical post  20 . Solar unit  18  includes a solar cell  28  connected to a storage battery  30 . The solar cell  28  has sufficient output capability to power containment transmitter device  16  and charge the storage battery  30  simultaneously. The storage battery  30  is capable of sourcing enough power for containment transmitter assembly  12  to permit reliable operation for extended periods when light is not available. Preferably, the storage battery  30  is a 4.5 ampere-hour battery. Transmitter device  16  transmits signals  22 , which may be reflected off of ground surface  24 . Signals  22  include both radio frequency (RF) reference signals (also referred to as synchronization signals) and lower frequency electromagnetic ranging signals. Containment transmitter assembly  12  includes a audio/video display  26  for displaying information, such as a built in test status and battery charge level. 
     As illustrated in FIG. 3A, containment transmitter assembly  12  and receiver assembly  14  cooperate to effectively divide the area surrounding containment transmitter assembly  12  into four zones: a confinement zone  100 , a low correction zone  102 , a high correction zone  104  and an outer, or OFF, zone  106 . In the illustration of FIG. 3A, zones  100 ,  102  and  104  are shown to be substantially circular, however, those skilled in the art will recognize that the actual shape of the perimeter of each of zones  100 ,  102  and  104  will depend upon several factors, such as for example the amount and type of interference which may be experienced in the various zones, e.g., ground clutter. 
     The four zones  100 ,  102 ,  104  and  106  are defined in relation to the length of three radii, or distances, as measured from the location of containment transmitter assembly  12 : distance D 1 , distance D 2 , and distance D 3 . Distance D 1  defines the perimeter of confinement zone  100 . Low correction zone  102  is defined by the difference between perimeter distances D 1  and D 2 . High correction zone  104  is defined by the difference between perimeter distances D 2  and D 3 . Outer zone  106  is defined as any location beyond containment transmitter assembly  12  at a distance greater than distance D 3 . In preferred embodiments of the invention, each of the distances D 1 , D 2  and D 3  are defined based upon an associated signal strength of the received electromagnetic ranging signal. 
     While animal  15  is within confinement zone  100 , no stimulation is provided to animal  15  by receiver assembly  14 . If animal  15  leaves confinement zone  100  and enters low correction zone  102 , then receiver assembly  14  emits an audio stimulation, without being accompanied by a tactile stimulation (e.g., electrical shock or vibration), for a predetermined period of time. If, after the predetermined period of time animal  15  has not returned to confinement zone  100 , then animal  15  will receive from receiver assembly  14  the audio stimulation accompanied by a low level tactile stimulation. If animal  15  continues to wander away from confinement zone  100  and enters high correction zone  104 , a high level tactile stimulation will be applied to animal  15  by receiver assembly  14 . If, however, animal  15  continues to wander away from confinement zone  100  and enters outer zone  106 , animal  15  will receive no further stimulation from receiver assembly  14 . Thus, animal  15  ceases receiving correction stimuli once animal  15  exceeds the distance D 3  from the transmitter, to thereby spare animal  15  from unnecessary discomfort due to unproductive corrective stimulation. If, after the stimulation timeout has occurred, the animal re-enters the containment zone, no corrective stimulation is applied. This allows the animal to re-enter the desired confinement zone  100  area without being punished. Once within the confinement zone for a predetermined time, the system re-enables. Once the system re-enables, any attempt to exit the confinement zone  100  will result in stimulation as described previously in this paragraph. 
     Both the transmitter  12  and receiver  14  have built-in-test circuitry to check for internal hardware failures. If either containment transmitter assembly  12  or receiver assembly  14  suffer a hardware failure, receiver assembly  14  is structured such that animal  15  will not receive a stimulation. 
     FIG. 3B illustrates a second boundary configuration that uses three zones: a confinement zone  200 , a correction zone  202  and an outer, or OFF, zone  204 . In the illustration of FIG. 3B, zones  200  and  202  are shown to be substantially circular, however, those skilled in the art will recognize that the actual shape of the perimeter of each of zones  200  and  202  will depend upon several factors, such as for example the amount and type of interference which may be experienced in the various zones, e.g., ground clutter. 
     The three zones  200 ,  202  and  204  are defined in relation to the length of two radii, or distances, as measured from the location of containment transmitter assembly  12 : distance D 4  and distance D 5 . Distance D 4  defines the perimeter of confinement zone  200 . Correction zone  202  is defined by the difference between perimeter distances D 4  and D 5 . Outer zone  204  is defined as any location beyond containment transmitter assembly  12  at a distance greater than distance D 5 . In preferred embodiments of the invention, each of the distances D 4  and D 5  are defined based upon an associated signal strength of the received electromagnetic ranging signal. 
     While animal  15  is within confinement zone  200 , no stimulation is provided to animal  15  by receiver assembly  14 . If animal  15  leaves confinement zone  200  and enters correction zone  202 , then receiver assembly  14  emits an audio stimulation accompanied by a progressively increasing tactile stimulation (e.g., electrical shock or vibration), for a predetermined period of time. If, after the predetermined period of time animal  15  has not returned to confinement zone  200 , the tactile stimulation is ceased in order to prevent over exposure of animal to stimulation. If, animal  15  continues to wander away from confinement zone  200  and enters outer zone  204 , animal  15  will receive no further stimulation from receiver assembly  14 . Thus, animal  15  ceases receiving correction stimuli once animal  15  exceeds the distance D 5  from the transmitter, to thereby spare animal  15  from unnecessary discomfort due to unproductive corrective stimulation. If, after the stimulation timeout has occurred, the animal re-enters the confinement zone  200 , no corrective stimulation is applied. This allows the animal to re-enter the desired confinement zone  200  without being punished. Once within confinement zone  200  for a predetermined time, the system re-enables. Once the system re-enables any attempt to exit the confinement zone  200  will result in stimulation as described previously in this paragraph. 
     Again, both the containment transmitter assembly  12  and receiver assembly  14  have built-in-test circuitry to check for internal hardware failures. If either containment transmitter assembly  12  or receiver assembly  14  suffer a hardware failure, receiver assembly  14  is structured such that animal  15  will not receive a stimulation. 
     Containment transmitter assembly  12  and receiver assembly  14  will now be described with reference to FIGS. 4 and 5. 
     Referring to FIG. 4, transmitter device  16  includes a microcontroller  32  which controls audio/video display  26  through an encoder  34 . Microcontroller  32  also controls a transmitter  36  which transmits radio frequency (RF) synchronization signals via an antenna  38 . Also, microcontroller  32  controls electromagnetic ranging signal transmitter  40  in order to cause an omnidirectional electromagnetic signal to be transmitted from an antenna  42 . The microcontroller  32  controls a Built-In-Test (BIT) circuit  43  that monitors and reports the health of the unit via an antenna  45 . 
     In order to efficiently use time and keep system latency to a minimum, the RF synchronizing signal and the electromagnetic ranging signal are sequenced to a specific timetable to allow power consuming hardware to be enabled for the minimum amount of time required. An example of this time sequencing is described herein. A 114 milliscecond (ms) 16.529 kilohertz (kHz) electromagnetic ranging signal pulse is sent, followed by a 20 ms wide FM coded 27 megahertz (MHz) synchronization signal pulse sent 32 ms after the start of the ranging signal. These signals are sent in bursts at a rate of approximately 4 bursts per second (every 0.25 seconds), which is the response latency of the system. Both signals are approximately omnidirectional. Transmitter  36  transmits the 27 MHz synchronization signal to qualify/correlate the 16.529 kHz electromagnetic ranging signal pulse. 
     Since the 27 MHz synchronization signal is capable of reaching beyond the sensing range of the 16.529 kHz ranging signal, the synchronization signal is uniquely coded with the Electronic ID of the system so that adjacent systems will not false alarm or interfere. The BIT circuitry  43  monitors the output of the 16.529 kHz signal to verify that it is transmitted. If the BIT circuitry  43  does not receive a valid indication that the 16.529 kHz ranging signal is being sent, containment transmitter assembly  12  suspends transmission of the 27 MHz synchronization reference signal. The absence of the 27 MHz synchronization signal at the receiver prohibits activation of the stimulation circuitry. Also, for each system, the approximately 4 burst per second transmit rate could be staggered slightly for differently coded reference signals to help eliminate transmission collisions for co-located systems. The 27 MHz synchronization signal uses about 26 milliamps of current peak with the resulting average transmit current being approximately 2.1 milliamps. The 16.529 kHz electromagnetic ranging signal uses a peak current of approximately 9.2 milliamps with an average transmit current being approximately 4.3 milliaiips. With the remaining circuitry using an additional 500 microamps the total average current drain of the containment transmitter assembly  12  is 7.0 milliamps. Thus, using a solar array with 50 milliamp output capability along with a storage battery  30  of sufficient capacity will permit containment transmitter assembly  12  to run continuously without interruption with a minimum of available sun light. 
     As shown in FIG. 5, receiver assembly  14  includes an antenna  44 , a radio frequency receiver  46 , a microcontroller  48 , an antenna  52 , a superheterodyne narrow band receiver  54 , an audio driver  58 , a high voltage generator  60 , a BIT Circuit  61  and a battery  66 . The RF synchronization signal emitted by antenna  38  of containment transmitter assembly  12  is received by antenna  44  of receiver assembly  14 . Receiver  46  processes the RF synchronization signals received by antenna  44  that are on the frequency of the radio frequency signals produced by transmitter  36 , which is preferably 27 MHz. Receiver  46  then sends the received data stream to microcontroller  48  on a data line  50 . The microcontroller  48  then does the final processing on the signal to determine that a RF synchronization signal of the frequency of interest has been received. Antenna  52  of receiver assembly  14  receives the electromagnetic ranging signal emitted by transmitter  40 . Then, superheterodyne narrow band receiver  54  sends a signal on data line  56  indicating to microcontroller  48  that an electromagnetic ranging signal within the narrow band of receiver  54  has been received. This narrow band includes the frequency of 16.529 kHz. Preferably, each of antenna  44  and antenna  52  is an omnidirectional antenna, and can be for example, a ferrite core or triplexer antenna. 
     Microcontroller  48  selectively turns on an audio driver  58  and/or a high voltage generator  60  dependent upon the detected signal strength of the received electromagnetic ranging signals, as described in more detail below. Audio driver  58  drives a speaker  62  which emits an audible warning signal to the animal. Based on the control signals supplied by microcontroller  48  via conductor  63 , high voltage generator  60  selectively produces a voltage difference between probes  64  in order to apply an electrical stimulus to the animal when probes  64  are in contact with the body of animal  15 . As is well known, receiver assembly  14  can be attached to the dog&#39;s collar such that probes  64  are pressed or biased against the dogs fur and/or skin. Microcontroller  48 , audio driver  58  and high voltage generator  60  are all powered by battery  66 , which may be a replaceable lithium battery with a capacity of 1400 milliamp hours. 
     Referring again to FIG. 3A and 3B, prior to use with an animal, containment transmitter assembly  12  is initialized to establish the desired containment radius D 1 /D 4 , which in turn is used to define the size of confinement zone  100 / 200 . To initialize containment transmitter assembly  12 , the output power of the 16.529 kHz electromagnetic ranging signal is adjusted to provide the desired containment radius. In an alternate embodiment of the invention, the containment radius D 1 /D 4  could be set at the receiver. This would be accomplished by having the transmitter output the ranging signal at a constant level which would yield the maximum containment radius for the system. The receiver would then be taken to a distance (D 1 /D 4 ) where the desired containment radius is to be set. The receiver would then be put in a calibration mode and would sample the signal to noise ratio (SNR) at that point and store this value in memory. The receiver would then compare all future received ranging signals to this SNR value. If the SNR is greater than the stored value the receiver would assume it is inside the containment radius. If the SNR is below the stored value, the receiver would assume it is outside of the containment radius and tone/stimulate accordingly. 
     Receiver assembly  14  can use a 1400 milliamp-hour replaceable lithium battery  66  as its power source. Receiver  54  can use a micropower 16 kHz current starved CMOS inverter amplifier, with a micropower MOSFET mixer to provide a 150 hertz center intermediate frequency (IF). The IF uses a micropower active filter op amp to provide the 10 hertz final bandwidth for optimum sensitivity and interference rejection. Total quiescent current for receiver  54  is approximately 100 microamps. The 27 MHz reference receiver  46  is time synchronized to the 27 MHz transmitter  36  and only powers up when a transmission is anticipated. This architecture minimizes the “on time” for 27 MHz receiver  46  and greatly reduces power consumption for the unit. When receiver  46  is initially synchronized to transmitter  36 , receiver  46  is powered continuously until the 27 MHz synchronization signal is acquired. Once acquired, receiver  46  is powered up only once every 250 milliseconds to re-synchronize the anticipated reference radio signal. If the synchronization signal is lost for any reason, receiver  46  stays on to re-acquire it. With a peak current draw of 4 milliamps, the average reference receiver current is 450 microamps. Since microcontroller  48  uses a 32 kHz local oscillator clock, microcontroller current drain is only 10 microamps, with total quiescent current being 560 microamps. This yields approximately 90 days of continuous operation for receiver assembly  14 . 
     After the FM coded 27 MHz synchronization signal is received by receiver assembly  14 , receiver assembly  14  then determines if the 16.529 kHz electromagnetic ranging pulse is present. If not present, the microcontroller determines that the receiver assembly  14 , and thus animal  15 , is out of the confinement zone and initiates a warning tone along with the lowest level tactile stimulation. This process is repeated with the tactile stimulation level increasing up to the maximum level unless the unit detects the presence of the 16.529 kHz ranging signal at the appropriate time in 4 successive windows. Once four successive decodes of the 16.529 kHz ranging signal are detected stimulation is stopped. Once twenty successive decodes of the 16.529 kHz ranging signal are detected the tactile stimulation level is reset to the lowest level. This sequencing allows the animal to re-enter the containment zone without receiving a correction. 
     The confinement system  10  operates in a manner to ensure that unproductive and/or unwarranted corrective signals are not applied to the animal. System  10  is designed so that if a hardware failure occurs at either the transmitter or receiver, no false shock signal can be discerned with an uncorrelated 16.529 kHz electromagnetic signal reception. Such uncorrelated electromagnetic pulse reception may be from any of several high amplitude broad noise sources, e.g., car ignitions, televisions, appliances, etc. A time based filtering algorithm allows very tight windowing for anticipated electromagnetic ranging pulses, and ensures that the uncorrelated electromagnetic pulse reception is not regarded as an electromagnetic ranging signal emitted by containment transmitter assembly  12 . 
     Additionally, the receiver assembly  14  is designed to accept signals from the separate and portable training transmitter  13 . Training transmitter  13  can be a handheld transmitter operating at 27 MHz and capable of transmitting different data packets corresponding to different commands, such as those available from Innotek, Inc. The receiver assembly  14  processes these commands received from training transmitter  13  and performs the desired action. These actions consist of applying different levels of tactile stimulation with or without an accompanying tone. Also, the unit may emit a tone without tactile stimulation. Receiver assembly  14  is designed to work with the containment transmitter assembly  12  enabled alone, the training transmitter  13  enabled alone or both transmitters  12 ,  13  enabled at the same time. When both transmitters  12 ,  13  are enabled, an additional command sent from training transmitter  13  is a containment field disable command which can temporarily or permanently disable processing of the containment transmitter  12  signals within receiver assembly  14 . 
     In the embodiment shown and described above, containment transmitter assembly  12  has been described as transmitting a radio frequency synchronization (reference) signal and an electromagnetic ranging signal. However, it is to be understood that the method and system of the present invention can be carried out with other types of signals which propagate through air, so long as the synchronization signal and the ranging signal are distinguishable and have signal strengths which permit different signal propagation distances. Also, in the embodiment shown and described above, the radio frequency synchronization signal is transmitted during the electromagnetic ranging signal. However, it is to be understood that the electromagnetic ranging signal can also be transmitted before or after the radio frequency synchronization signal. 
     The preferred tactile stimulus applied to the animal has been described herein as an electrical shock. However, it is to be understood that the stimulus can also be any other type of unpleasant sensation or irritant, such as an audible tone, a smell, a spray, or a sensation caused by a mechanical device. 
     While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.