Patent Publication Number: US-2007115119-A1

Title: A&amp;m for electrodynamic intrusion

Description:
This application is based on and claims priority of U.S. Provisional Ser. No. 60/168,782 filed Dec. 2, 1999. 
    
    
     SUMMARY OF THE INVENTION  
      The present invention serves to produce/generate and monitor electrodynamic interactions between earthed (i.e., electrically grounded) metallic/conductive structures and their ambient electromagnetic (EM) surroundings. The present invention utilizes a novel adaptive resonance-based electromagnetic signal generation and analysis technique, that can be practically utilized as a theft deterrent system for heavy equipment, or for intrusion detection in structures and on long baseline barrier (i.e., fence) applications. The novel and key component in all of these applications is the ability of the system to function with earthed structures (i.e., metal buildings or structures containing large conductive members, fences and tracked or bladed heavy equipment) and in a changing EM ambient  
      Unlike other tamper/intrusion detection methods (i.e., ultrasound, vibration, microwave, infrared, laser etc.), the present invention uses the entire structure that is to be monitored as the active sensing element, thereby eliminating zone coverage limitations/problems/ issues.  
      In a typical practical application such as for a “Heavy Equipment Theft Deterrent/Loss Prevention System”, the present invention is capable of detecting unwanted intrusion or tampering on heavy equipment. It remotely alerts (via paging network or cellular link) the equipment owner or equipment supervisor when intrusion is detected. Optional practical features include engine fire detection (thermal sensing) and low vehicle battery alerts.  
     BACKGROUND OF THE INVENTION  
      The present invention utilizes a novel adaptive “EM Resonance” is technique to provide for intrusion detection. This technique provides a far greater degree of performance and lower production costs, in comparison to prior art intrusion detection methods and apparatus.  
      With a view towards a practical application such as the protection of heavy equipment (i.e., bulldozer or excavator), a brief overview of the adaptive resonance technique will now be given. The metal frame and chassis of a piece of heavy equipment can be considered as a single electrically conductive (and usually magnetically permeable) maw having certain electromagnetic characteristics. These characteristics would normally be fairly easily definable and hence usable for intrusion detection via various electromagnetic means (i.e., if the equipment structure was electrically isolated from its surroundings). However, most such pieces of heavy equipment, including rubber-tired ones, usually have an implement or blade etc. In contact with the earth or ground when parked and at rest  
      As a result, the equipment mass/structure is effectively electrically short-circuited to the earth and although the earth is not considered a very good conductor of electricity, it can range from fairly good (when very wet/or high ion content) to fairly poor (when very dry). This range of electrical conductivity is quite broad and presents a major stumbling block to using electromagnetic means for intrusion detection in such applications.  
      The reason for this is that the equipment mass essentially couples to, and becomes part and parcel of, what is called the radio frequency ground plane. This coupling can vary dramatically, not just due to is equipment mass, size, or topology, but mainly due to ground conductivity and further, according to the frequency of any applied or incident electromagnetic energy.  
      In the novel method according to one embodiment of the present invention, a small amount of electromagnetic energy (RF) is emitted (radiated) into the so-called near-field space surrounding the equipment. Due to the nature of the coupling to the ground plane, this radiation pattern is essentially omni-directional and roughly in the shape of the horizontal outline of the equipment. The energy absorbed/reflected within this field space/zone is a function of the frequency of the EM radiation, its power and the EM susceptibility of the ground plane, as well as the presence of any nearby obstructions. Accordingly, this can vary greatly.  
      The amount of EM energy that is absorbed by everything (EM ambient) surrounding the emitter (antenna) is measured and continually monitored by the system. This will be at a minimum when everything is at EM resonance (we can do this because only at resonance, will half the power radiate into free space, and the other half be reflected).  
      Any changes in the near field conditions will affect the reflected energy, but these changes are usually only slowly time-variant or small in effect. Further, the intrusion of a fairly conductive body (such as a human) into the near-field (at ground level) will not in itself perceptibly affect reflected energy (i.e., due to varying absorption), however, contact with the equipment (or even EM coupling as through gloves) will dramatically affect reflected energy and hence, the systems resonance point.  
      The apparatus according to the present invention, continually adapts itself to the normal slowly time-varying EM resonance point (even due to rainfall etc.) and it does this many times per second. It is immune to false triggering caused by ambient changes and even to animals brushing against the equipment However, tampering attempts involving the use of tools (i.e., hydraulic cylinder or implement detachment) will cause a sufficiently rapid and gross enough EM resonance shift to trigger the system.  
      Although generically speaking, the method and apparatus according to the present invention falls under the heading of RF proximity sensing or detection, there appears to be no prior art anticipating the use of adaptive resonance means.  
      Further, according to another embodiment d the present invention, s there is shown the use of a two-way paging network (or cellular network) for the wireless notification of disturbances/intrusions/tampering, power line carrier based communications with fire/temperature sensors, a starter disabling attachment, and a visible dye/radioactive marker attachment.  
      Aside from the application towards heavy equipment, the present invention has application and promise for the following—boats (with large metallic sub-structures), grounded metal fencing, grounded metal buildings/structures, and even in ground insulated domestic wood-structured housing, as an alarm therefore (i.e., if the overall structure employs metal forced-air heat ducting or metal hot water piping).  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  shows schematically, a preferred embodiment of the method and apparatus according to the present invention, wherein the radiated EM energy is of fixed frequency and only changes in the ambient absorption of the EM radiation are monitored;  
       FIG. 2  shows schematically, a more preferred embodiment of the method and apparatus according to the present invention, wherein the radiated EM energy is of variable frequency and can thereby be continually tuned to track the resonant frequency of the overall system, which occurs at the point of maximum ambient absorption of the EM radiation;  
       FIG. 3  shows partially pictorially and partially schematically, the method and apparatus according to the present invention when applied to a metal-tracked heavy equipment structure;  
       FIG. 4  shows graphically, the change in the resonant frequency versus time, of the overall system shown in  FIG. 3 , due to both natural ambient variations and an actual intrusion/tampering event.  
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS  
      With reference now to  FIG. 1 , there is shown a preferred embodiment of the method and apparatus according to the present invention, s wherein the radiated EM energy is of fixed frequency and only changes in the ambient absorption of the EM radiation are monitored. As shown in  FIG. 1 , the system is depicted as being contained within the dashed lines  1 . External connections comprise two electrical connections, a chassis ground  3  and positive electrical supply  2 . Electrical power is  1 o therefore supplied to the present invention from an external battery supply such as may be found on a host vehicle such as an earth moving apparatus or the like. Said chassis ground  3  therefore serves as the return path for said electrical power flow. A further external connection of an electromagnetic nature is also provided as indicated is by electromagnetic wave propagation  51  and will be described in detail later. Said positive electrical supply  2  typically has potential of 12 or 24 volts and may deviate considerably below and above this value depending on various factors. Transient suppressor  4  is provided to quench or bypass high voltage transients that may appear due to inductive load dumping or battery boosting of said host vehicle.  
      Further, diode  5  is provided for reverse polarity protection. Line  14  therefore always lies at a positive potential that is somewhat representative of the host vehicle battery voltage.  
      There is also shown a microcontroller or microprocessor  6 , such as is well known in the art, and it has various digital and analog input and output capabilities, which are utilized by the present invention and will now be described. Said internal supply line  14  also provides a host battery potential signal to an analog input (ADO) of said microcontroller (uC)  6  via line  15 . This all uC  6  to perform an analog to digital conversion of said host battery signal at chosen intervals and thereby track and determine the condition of said host battery, or even the physical disconnection thereof (i.e., cutting of said power supply line  2  or battery terminal disconnection.) Said internal supply line  14  provides a positive electrical input to a power switch  13 , which can be of a bipolar or field effect transistor type, such as are well known in the art. Said power switch  13  is controlled via line  12  from a pulse-width modulated output (PWMI) from said uC  6 . The output line  8  from said power switch  13  is connected to an internal backup battery  9  (nominally 12V @3000 mA/hr capacity), with line  10  therefrom providing the system internal ground. The positive terminal of said internal backup battery  9  is also connected via said power switch output line  8  and line  16 , to a further analog input (ADI) of said uC B. This allows uC  8  to perform an analog to digital conversion of said backup battery potential at chosen intervals and thereby track and determine the condition of said backup battery.  
      Accordingly, uC  6  can control said power switch  13  with a pulse-width modulated signal via line  12 , in order to maintain a set level of potential (and charge) of said backup battery  9  and also to supply the requisite power (nominally 12V) for the rest of the system. Also shown, is voltage regulator  7 , which serves to regulate the supply potential and distribute said supply potential to various components and sub-blocks of the system via line  11 . uC  6  is also powered from said line  11  and is grounded via  55 .  
      Shown further, is a high voltage inverter and drive circuit  18 , which serves to raise the nominal unregulated 12V system voltage to around 1000V, provide capacitive storage (not shown), and a high voltage trigger pulse (not shown) in order to produce a periodic gas discharge within flash lamp i  9 , which is of the common xenon type. Said inverter and drive circuit  18  is under the control of a digital output (P 1 ) from said uC  6  via line  17 . In this manner, under firmware control, uC  6  can cause a high intensity luminous discharge from said lamp  19  (i.e., strobe) for the purpose of visibly attracting attention when necessary, or for producing visible feedback prompts.  
      Also shown, is a power switch  30 , which serves to drive an acoustic transducer  31 . Said power switch  30  is under the control of a pulse-width modulated output (PWM 2 ) from said uC  6  via line  29 . In this manner, uC  6  can produce a high intensity audible acoustic emission for the purpose of audibly attracting attention when necessary, or for producing audible feedback prompts. Further, the frequency, duration and intensity of the generated audible acoustic emission is under the control of uC  6  by virtue of b generated pulse-width modulated output, which is under firmware control.  
      The above described two subsystems serve to produce locally visible and audible emissions for warning and other purposes. The system further includes a radio-frequency transmitter and modem  35  (e.g., paging transmitter, cellular, VHF or UHF etc.), which the system can use for one-way transmittal of data to a remote location. The RF output of said RF transmitter and modem  35  is fed by line  34  through bandpass filter components  33  and  32  to the system antenna  48  (said antenna is shared by a number of system sub-blocks.) uC  6  controls said RF transmitter and modem  35  via line  36  from a digital output (P 2 ). Further, uC  6  can present formatted data from its serial output (S 1 ) to said RF transmitter and modem  35  via line  37 .  
      Accordingly, the system can thereby remotely (via RF) report intrusions (will be described in detail later), host battery disconnection, battery status (both host and internal backup), system status and malfunctions and various other optional parameters.  
      As an example thereof, one may have thermalfire sensors deployed on said host vehicle (i.e., near the engine) and these can be of the type that utilize relatively low frequency RF carriers over the existing host vehicle power wiring. Although not shown such a sensor is powered from the host vehicle power wiring and when triggered (i.e., high temperature) such said sensor will superimpose said RF carrier at a certain frequency onto said power wiring (this approach greatly minimizes sensor installation requirements.)  
      In accordance with such, there is shown a method for receiving such an RF carrier from said sensor. Line  20  is seen to be connected to the host vehicle positive electrical supply  2 . Bandpass filter components  21  and  22  serve to localize spectral sensitivity to the RF frequency region of interest (not shown are possible requisite amplifier stages.) The output thereof is fed via line  23  to a frequency detector input (F 1 ) on uC  6 . The appearance on said host vehicle&#39;s power wiring of an appropriate frequency for a sufficient duration of time (i.e., from a temperature sensor) can thereby be detected by said uC  6  and classified via firmware in order to produce an appropriate response or action by the system.  
      Further shown in  FIG. 1 , is a remote control radio-frequency receiver  24  (e.g., 300 or 308 MHz), which the system can use for the reception of RF signals from a remote control transmitter (the remote control transmitter is not shown.) This is utilized for short range (i.e., local area to the host vehicle, &lt;200 m) for arming and disarming the system etc. Said RF receiver  24  is fed via line  26  from bandpass filter components  27  and  28  from shared system antenna  48 . The demodulated output from RF receiver  24  is presented to a frequency detector input (F 2 ) on uC  6  via line  25 .  
      Finally, for the fundamental purpose of detecting intrusions and disturbances electromagnetically, there is shown an RF transmitter  38 , whose output  47  is coupled via a transmission line or coax cable comprised of conductor  50  and shield/ground plane segment  49 , to said shared system antenna  48  and to a chassis ground point local thereto. Said RF transmitter  38  is of a fixed frequency type in this preferred embodiment, said frequency chosen to fit within the spectral resonance range for a given size/surface area of possible host vehicles. Said RF transmitter  38  is under the control of uC  6  from digital output (P 3 ) via line  39  and typically said RF transmitter  38  is turned on at regular intervals and for a specific duration (i.e., pulsed), but it may also be energized at pseudo-random intervals.  
      When so energized, said RF transmitter  38  radiates an electromagnetic (RF) field from shared system antenna  48  and the near field (primarily near field and not the far field) absorption and reflection of electromagnetic energy by ambient surroundings and objects will determine the net effective radiated electromagnetic energy, and consequently, the amount of power drawn from the system power supply by said RF transmitter  38 . Further, there are shown external coupling components  52  (resistive) and  53  (capacitive), which serve to represent the electromagnetic coupling parameters associated with a portion or portions of said host vehicle being in contact with the earth  54 . There will be continuous variability in said external coupling parameters (due to changes in the earth&#39;s conductivity etc.), and these changes must be tracked and gross disturbances and intrusions in the near field must be isolated.  
      To accomplish this, uC  6  monitors the power consumption of RF transmitter  38 , which will directly vary according to the previously described variations in the near field absorption and reflection characteristics (both continuous and transient.) Accordingly, an analog input (AD 2 ) on uC  6  is provided with a signal on line  43  from resistor  45 , which is in series with a direct connection to the unregulated positive power supply bus of the system. Capacitor  44  serves to provide a small degree of filtering or smoothing. Said RF transmitter  38  is provided its main RF transmit power from the unregulated positive power supply bus through series resistor  46 . Line  42  connects is power input to series resistor  41 , which via line  40 , presents a signal to an analog input (AD 3 ) on uC  6 . Capacitor  56  serves to provide filtering. This last signal will vary in direct proportion to the power consumption of said RF transmitter  38 . Via the monitoring of the differences between the two separate analog signals so acquired (i.e., when RF transmitter  38  is energized), uC  6  and its resident firmware can determine and track changes in the near field electromagnetic interactions, thereby detecting sudden gross disturbances and shift such as are indicative of an intrusion and not of any natural drift.  
      With specific reference now to  FIG. 2 , there is shown a more preferred embodiment of the method and apparatus according to the present invention, wherein the radiated EM energy is of variable frequency. This serves to maximize near field EM interaction through tuning said EM frequency to the resonance frequency of the overall system. Hence, changes in the ambient absorption of the EM radiation are then monitored by tracking said variable frequency (i.e., resonance frequency.)  
      As shown in  FIG. 2 , the system is depicted as being contained within the dashed lines  100 . External connections comprise two electrical connections, a chassis ground  102  and positive electrical supply  101 . Electrical power is therefore supplied to the present invention from an external battery supply such as may be found on a host vehicle such as an earth moving apparatus or the like. Said chassis ground  102  therefore serves as the return path for said electrical power flow. A further external connection of an electromagnetic nature is also provided as indicated by electromagnetic wave propagation  151  and will be described in detail later. Said positive electrical supply  101  typically has potential of 12 or 24 volts and may deviate considerably below and above this value depending on various factors. Transient suppressor  104  is provided to quench or bypass high voltage transient that may appear due to inductive load dumping or battery boosting of said host vehicle. Further, diode  105  is provided for reverse polarity protection. Line  114  therefore always lies at a positive potential that is somewhat representative of the host vehicle battery voltage.  
      There is also shown a microcontroller or microprocessor  106 , such as is well known in the art, and it has various digital and analog input and output capabilities, which are utilized by the present invention and will now be described. Said internal supply line  114  also provides a host battery potential signal to an analog input (AD 0 ) of said microcontroller (uC)  106  via line  115 . This allows uC  106  to perform an analog to digital conversion of said host battery signal at chosen intervals and thereby track and determine the condition of said host battery, or even the physical disconnection thereof (i.e., cutting of said power supply line  101  or battery terminal disconnection.) Said internal supply line  114  provides a positive electrical input to a power switch  113 , which can be of a bipolar or field-effect transistor type, such as are well known in the art. Said power switch  113  is controlled via line  116  from a pulse-width modulated output (PWMI) from said uC  106 . The output line  108  from said power switch  113  is connected to an internal backup battery  109  (nominally 12V @3000 mA/hr capacity), with line  110  therefrom providing the system internal ground. The positive terminal of said internal backup battery  109  is also connected via said power switch output line  108  and line  112 , to a further analog input (AD 1 ) of said uC  106 . This allows uC  106  to perform an analog to digital conversion of said backup battery potential at chosen intervals and thereby track and determine the condition of said backup battery.  
      Accordingly, uC  106  can control said power switch  113  with a pulse-width modulated signal via line  116 , in order to maintain a set level of potential (and charge) of said backup battery  109  and also to supply the requisite power (nominally 12V) for the rest of the system. Also s shown, is voltage regulator  107 , which serves to regulate the supply potential and distribute said supply potential to various components and sub-blocks of the system via line  111 . uC  106  is also powered from said line  111  and is grounded via  155 .  
      Shown further, is a high voltage inverter and drive circuit  118 , which serves to raise the nominal unregulated 12V system voltage to around 1000V, provide capacitive storage (not shown), and a high voltage trigger pulse (not shown) in order to produce a periodic gas discharge within flash lamp  119 , which is of the common xenon type. Said inverter and drive circuit  118  is under the control of a digital output (P 1 ) from said uC  106  via line  117 . In this manner, under firmware control, uC  108  can cause a high intensity luminous discharge from said lamp  119  (i.e., strobe) for the purpose of visibly attracting attention when necessary, or for producing visible feedback prompts.  
      Also shown, is a power switch  130 , which serves to drive an acoustic transducer  131 . Said power switch  130  is under the control of a pulse-width modulated output (PWM 2 ) from said uC  106  via line  129 . In this manner, uC  106  can produce a high intensity audible acoustic emission for the purpose of audibly attracting attention when necessary, or for producing audible feedback prompts. Further, the frequency, duration and intensity of the generated audible acoustic emission is under the control of uC  106  by virtue of its generated pulse-width modulated output, which is under firmware control.  
      The above described two subsystems serve to produce locally visible and audible emissions for warning and other purposes. The system further includes a radio-frequency transmitter and modem  135  (e.g., paging transmitter, cellular, VHF or UHF etc.), which the system can use for one-way transmittal of data to a remote location. The RF output of said RF transmitter and modem  135  is fed by line  134  through bandpass filter components  133  and  132  to the system antenna  148  (said antenna is shared by a number of system sub-blocks.) uC  106  controls said RF transmitter and modem  135  via line  136  from a digital output (P 2 ). Further, uC  106  can present formatted data from its serial output (S 1 ) to said RF transmitter and modem  135  is via line  137 .  
      Accordingly, the system can thereby remotely (via RF) report intrusions (will be described in detail later), host battery disconnection, battery status (both host and internal backup), system status and malfunctions and various other optional parameters.  
      As an example thereof, one may have thermal/fire sensors deployed on said host vehicle (i.e., near the engine) and these can be of the type that utilize relatively low frequency RF carriers over the existing host vehicle power wiring. Although not shown such a sensor is powered from the host vehicle power wiring and when triggered (i.e., high temperature) such said sensor will superimpose said RF carrier at a certain frequency onto said power wiring (this approach greatly minimizes sensor installation requirements.)  
      In accordance with such, there is shown a method for receiving such an RF carrier from said sensor. Line  120  is seen to be connected to the host vehicle positive electrical supply  101 . Bandpass filter components  121  and  122  serve to localize spectral sensitivity to the RF frequency region of interest (not shown are possible requisite amplifier stages.) The output thereof is fed via line  123  to a frequency detector input (F 1 ) on uC  106 . The appearance on said host vehicle&#39;s power wiring of an appropriate frequency for a sufficient duration of time (i.e., from a temperature sensor) can thereby be detected by said uC  108  and classified via firmware in order to produce an appropriate response or action by the system.  
      Further shown in  FIG. 2 , is a remote control radio-frequency receiver  124  (e.g., 300 or 308 MHz), which the system can use for the reception of RF signals from a remote control transmitter (the remote control transmitter is not shown.) This is utilized for short range (i.e., local area to the host vehicle, &lt;200 m) for arming and disarming the system etc. Said RF receiver  124  is fed via line  126  from bandpass filter components  127  and  128  from shared system antenna  148 . The demodulated output from RF receiver  124  is presented to a frequency detector input (F 2 ) on uC  106  via line  125 .  
      Finally, for the fundamental purpose of detecting intrusions and disturbances electromagnetically, there is shown an RF transmitter  138 , whose output  147  is coupled via a transmission line or coax cable comprised of conductor  150  and shield/ground plans segment  149 , to said shared system antenna  148  and to a chassis ground point local thereto. Said RF transmitter  138  is of a variable frequency type in this more preferred embodiment and its transmission frequency is controlled by uC  106  via serial data output (SI) over line  156 . Said RF transmitter  138  is under the control of uC  106  from digital output (P 3 ) via line  139  and typically said RF transmitter  138  is turned on at regular intervals and for a specific duration (i.e., pulsed), but it may also be energized at pseudo-random intervals.  
      When so energized, said RF transmitter  138  radiates an electromagnetic (RF) field from shared system antenna  148  and the near field (primarily near field and not the far field) absorption and reflection of electromagnetic energy by ambient surroundings and is objects will determine the net effective radiated electromagnetic energy, and consequently, the amount of power drawn from the system power supply by said RF transmitter  138 . Further, there are. shown external coupling components  152  (resistive) and  153  (capacitive), which serve to represent the electromagnetic coupling parameters associated with a portion or portions of said host vehicle being in contact with the earth  154 . There will be continuous variability in said external coupling parameters (due to changes in the earth&#39;s conductivity etc.), and these changes must be tracked and gross disturbances and intrusions in the near field must be isolated.  
      To accomplish this, uC  106  monitors the power consumption of RF transmitter  138 , which will directly vary according to the previously described variations in the near field absorption and reflection characteristics (both continuous and transient.) Accordingly, an analog Input (AD 2 ) on uC  106  is provided with a signal on line  143  from resistor  145 , which is in series with a direct connection to the unregulated positive power supply bus of the system. Capacitor  144  serves to provide a small degree of filtering or smoothing. Said RF transmitter  138  is provided its main RF transmit power from the unregulated positive power supply bus through series resistor  146 . Line  142  also connects this power input to series resistor  141 , which via line  140 , presents a signal to an analog input (AD 3 ) on uC  106 . Capacitor  157  serves to provide filtering. This last signal will vary in direct proportion to the power consumption of said RF transmitter  138 . Via the monitoring of the differences between the two separate analog signals so acquired (i.e., when RF transmitter  138  is energized), uC  106  and its resident firmware can determine and track changes in the near field electromagnetic interactions, continuously adjust the frequency of RF transmitter  138  to that of maximum near field absorption (occurs at resonance) and thereby more effectively detect sudden gross disturbances and shift such as are indicative of an intrusion and not of any natural drift.  
      With reference now to  FIG. 3 , there is shown a host vehicle  200 , such as of the tracked earth moving type. The system antenna is depicted as  201  and its chassis ground plane connection is shown as  207 . The electromagnetic emission portion of the present invention (i.e., intrusion detection RF transmitter) is shown as  202 . Normally (if the host vehicle was isolated from the earth), the near field electromagnetic interactions would be stable and interaction with the earth  203  would include only the effects of capacitive coupling  205  and inductive coupling  206 . However, because a portion of said host vehicle may actually be in electrical contact with said earth  203 , as depicted by resistive coupling  204 , said three coupling parameters become extremely complex and for a given frequency, will exhibit long term electromagnetic variations and changes.  
      With reference to  FIG. 4 , there is shown a graph depicting typical long term electromagnetic variations and changes as experienced by the system according to the present invention. Said graph of  FIG. 4  shows the time (t) along its abscissa and the system resonant frequency (f) along its ordinate. The resonant frequency can be considered to be a function of the lumped coupling parameters as previously described (hence the title delta t-lumped parameter) and their changes over time. The resonant frequency  208  can be seen to vary and change more or is le smoothly over time, whereas  209  shows a gross and marked (and sudden) disturbance indicative of an intrusion into the near field.