Abstract:
A system for monitoring activities relating to movable and removable items within a vehicle is described. The system includes an electrical energy storage device, an energy harvesting device operable to store harvested energy in the electrical energy storage device, a sensor element configured to output signals corresponding to one or more of removal, installation, and a shift in position of a corresponding item within the vehicle, and a transmitter configured to receive the signals from the sensor element. The transmitter is also configured to transmit unique identification information and data corresponding to the signals received from the sensor element, where the unique identification information corresponds with a location of the item on the vehicle. The sensor element and the transmitter are configured to use energy from one or both of the energy harvesting device and the electrical energy storage device.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The field of the invention relates generally to maintaining search and inspection requirements for operation of individual aircraft, and more specifically, to methods and systems for sensing activity using energy harvesting devices. 
         [0002]    Many airline procedures are in place to ensure the safety of passengers, crew and equipment. In one instance, a visual inspection process of an airline interior, for example, may include visually looking for opened doors, visually looking for broken tamper evident tapes, and/or manually opening the various doors, panels, and covers generally found within a passenger airliner cabin. The process is conducted to visually inspect the spaces, or volumes, behind these devices, whether or not the doors, panels, and covers have been accessed. 
         [0003]    Visually inspecting these spaces and volumes is labor intensive and the process results in an incurred expense for the airline operator. The process may also result in an extended airport gate turn around time. The reality, however, is the vast majority of these spaces have not been accessed or otherwise tampered with. Therefore, the vast majority of visual inspections are not value added. 
         [0004]    Airplanes undergo a fairly rigorous inspection in the morning hours preceding the first flight of the day and further inspections are performed while cleaning the airplane between flights resulting in several man-hours per airplane per day. If any areas appear to be tampered with, a more thorough inspection will then be performed. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0005]    In one aspect, a system for monitoring activities relating to movable and removable items within a vehicle is provided. The system includes an electrical energy storage device, an energy harvesting device operable to store harvested energy in the electrical energy storage device, a sensor element configured to output signals corresponding to one or more of removal, installation, and a shift in position of a corresponding item within the vehicle, and a transmitter configured to receive the signals from the sensor element. The transmitter is also configured to transmit unique identification information and data corresponding to the signals received from the sensor element, where the unique identification information corresponds with a location of the item on the vehicle. The sensor element and the transmitter are configured to use energy from one or both of the energy harvesting device and the electrical energy storage device. 
         [0006]    In another aspect, a method for monitoring activities related to one or more items within an aircraft is provided. The method includes configuring the items such that at least one activity associated with the item is operable as a triggering event to a sensor, transmitting a unique identification code associated with the sensor to a monitoring device upon determining that a triggering event has occurred, and correlating the unique identification code with a physical location within an aircraft for purposes of physical inspection. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a flowchart illustrating a method for monitoring activities related to one or more items within an aircraft. 
           [0008]      FIG. 2  is a schematic view of a light assembly. 
           [0009]      FIG. 3  is a schematic view of a door sensor assembly. 
           [0010]      FIG. 4  is a schematic view of a sensor and transmitter combination mounted at an access door. 
           [0011]      FIG. 5  is a schematic view of an alternative sensor/transmitter configuration. 
           [0012]      FIG. 6  is a schematic view of a mechanically powered seat sensor assembly. 
           [0013]      FIG. 7  is a schematic view of a vibration powered seat sensor assembly. 
           [0014]      FIG. 8  is a schematic view of a return air grill sensor assembly. 
       
    
    
       [0015]    The features, functions, and advantages can be achieved independently in various embodiments of the present disclosure or may be combined in yet other embodiments in which further details can be seen with reference to the following description and drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    The methods and systems described herein are helpful in reducing costs and airport gate turnaround time associated with inspections of the various volumes, spaces, and doors associated with an aircraft. More specifically, the methods and systems relate to several specific devices, and associated methods, for wirelessly sensing modification, activity, and/or access events related to volumes, spaces or doors using various energy harvesting or “self-powered” sensors. These sensors are configured to detect and report such modification, activity and access events using wireless communications and the above mentioned battery-free sensors. 
         [0017]      FIG. 1  is flowchart  10  illustrating a method for monitoring activities related to one or more items within an aircraft. The method illustrated by flowchart  10  includes configuring  12  the items such that at least one activity associated with the item is operable as a triggering event to a sensor, transmitting  14  a unique identification code associated with the sensor to a monitoring device upon determining that a triggering event has occurred, and correlating  16  the unique identification code with a physical location within an aircraft for purposes of physical inspection. In one embodiment, a date and time of the triggering event is recorded in the monitoring device. 
         [0018]      FIG. 2  is a schematic view of a light assembly  100 . Light assembly  100  includes a wireless sensor/transmitter  102  that is powered by a photovoltaic cell  104 . The wireless sensor/transmitter  102  is installed in a light housing  110  in which one or more lamps  112  are installed, and to which a hinged light bezel  114  is attached. One or more sensors  120 , for example, a magnetic reed switch or a mechanical micro-switch, is utilized to sense when the light bezel  114  is in its normally installed position, or if it is fully or partially un-installed. 
         [0019]    In operation, sensor  120  is operable to alert the low power, wireless sensor/transmitter  102  of the installation state of the bezel  114  (e.g., if the bezel  114  is in a closed or open position). In one embodiment, the sensor/transmitter  102  is programmed to transmit a unique identification code and a state (open/closed) of the sensor/transmitter  102  whenever the sensed condition changes. The sensor/transmitter  102  may also be programmed to wirelessly transmit it&#39;s unique identification code on a periodic basis, whether the state of the sensor  120  has changed or not, to provide a “sign of life” signal. In one embodiment, the low power, wireless sensor/transmitter  102  is installed in the housing  110 , behind the light bezel  114 . 
         [0020]    The wireless sensor/transmitter  102  is powered by the lamps  112  behind the bezel  114 . A photovoltaic cell  104 , such as an amorphous silicon photovoltaic cell, is exposed to this light source. The cell  104  is utilized to maintain a charge on a battery and/or a capacitor (not shown in the Figure) which may or may not be located within the housing  110  or within the wireless sensor/transmitter  102 . The battery and/or super-capacitor provide the energy needed to power the wireless sensor/transmitter  102 . 
         [0021]    In the figure, a magnetic material  122  is bonded to the hinged light bezel  114  such that it is adjacent to sensor  120  when the bezel  120  is in the closed position. When the bezel  114  is opened (swung downward), the magnetic material  122  moves away from the sensor  120  and the sensor/transmitter  102 . In one embodiment, sensor  120  is a magnetic reed switch within the sensor transmitter  102  that senses that the magnetic material  122  is not nearby. When the magnetic material  112  is no longer proximate sensor  120 , the reed switch therein changes state, causing the sensor/transmitter  102  to transmit its identification number, and other data indicating that the sensor  120  does not sense the magnetic material  122 . Likewise, when the bezel  114  is closed, the sensor  120  senses the presence of the magnetic material (the reed switch again changes state) and the sensor/transmitter  102  transmits its identification number, and other data indicating that the switch is again closed. In one embodiment, a record of each bezel opening and closing occurrence is retained in a monitoring device so appropriate actions can be performed. 
         [0022]      FIG. 3  is a schematic view of a door sensor assembly  200 . Door sensor assembly  200  is a mechanically-powered wireless door sensor and transmitter. Specifically, a mechanically-powered wireless sensor/transmitter  202  is installed in a door  204  (as shown) or in door jamb such that the mechanical work in opening and/or closing of the door  204  may be converted into electrical power using a mechanical energy harvester  206  as it compresses and decompresses against a door stop  208 . This electrical power is used to transmit, over a wireless channel, an “opened” or “closed” signal, along with a unique identification number associated with the individual sensor/transmitter  202 . 
         [0023]    In one embodiment, the mechanical energy harvester of door assembly  200  may include a piezoelectric device that is caused to deflect or vibrate by the mechanical work, thus producing an electrical charge in the piezoelectric materials. In another embodiment, a piezoelectric material is bonded to an aircraft structure and is operable to undergo a strain based on a strain experienced by the aircraft structure under varying aircraft operational forces to produce the electrical charge; 
         [0024]    In another embodiment, the mechanical energy harvester includes an electro-dynamic device including a coil of wire. A magnetic field is caused to move relative to the coil of wire to produce an electric current in the coil of wire. In one specific embodiment, the polarity of the generated electric charge (or polarity of first half-cycle of AC generated power) may be sensed by the sensor/transmitter  202  to detect whether the door  204  is going through an opening” or “closing” event. 
         [0025]    Each wireless sensor/transmitter  202  generally includes one or more sensor(s), a microprocessor, and a radio transmitter. Additionally, each sensor/transmitter  202  includes a small energy storage device, such as a battery and/or a capacitor, in addition to an energy harvesting device. In various embodiments, the energy harvesting device converts ambient energy of one form (force, vibration, heat, flow, light) into electricity to power the sensor/transmitter  202  and/or charge an energy storage device. As a result, the sensor/transmitter  202  is completely wireless and powered either by a small energy storage device and/or by converting ambient energy in its surrounding environment. These energy generation and storage capabilities make the door assembly  200  very easy to install, particularly in a retrofit or after-market scenario, since no power or data wires need to be routed to the door assembly  200 . 
         [0026]    The sensor/transmitters  202  are, in one embodiment, configured to sample the sensor portion on a schedule (e.g. sample state of door every second). The sensor/transmitter  202  may also be triggered by an external event, related to where it is installed, to sense, for example, the act of physically opening a door. In another example, the sensor/transmitter  202  is configured to conform to a periodic schedule whereby it samples the state of the door every second and wirelessly reports whenever that state has changed, but at least every hour to provide a “sign of life” signal. As another example, the sensor portion of sensor/transmitter  202  is a switch that only awakens the microprocessor when it changes from an open to closed circuit, or visa versa. It is well known in the art of microprocessors to support such a polling or wake-on-demand function. As yet another example, the sensor/transmitter  202  includes a spring-loaded lever that is released when a hatch door is opened. This mechanical spring release action is converted to electricity and activates the sensor/transmitter  202  to transmit a corresponding message that indicates “hatch opened”. In this last example, the sensor transmitter  202  is powered by the change of state in the object it is intended to sense. 
         [0027]    As illustrated in  FIG. 4 , a mechanical energy harvester  230  and sensor/transmitter  232  combination may be mounted at an access door  234  such that when the access door  234  is opened or closed, a simple triggering device  236  on the door  234  triggers a spring device  238  such that mechanical energy harvester  230  commences to harvest the mechanical energy caused by the movement of the spring device  238 . This operation provides power to the sensor/transmitter  232  which sends a message indicating that the access door  234  has been moved from one position to another. In one embodiment, the mechanical energy harvester  230  includes an electro-dynamic harvesting device. The sensor/transmitter  232  may observe the electrical polarity generated by the mechanical energy harvester  230  (or polarity of first half-cycle of AC generated power) to determine the direction of motion of the triggering device  236 . 
         [0028]    Another packaging concept includes alternative energy harvesting devices connected to a sensor and transmitter combination, which may consist of, for example, a photovoltaic device exposed to a light source, such as sunlight or cabin lighting, a vibration harvesting device, such as a cantilevered piezoelectric beam, exposed to airplane or operational vibration, or a thermoelectric device exposed to a thermal gradient, such as a hot hydraulic line or the thermal gradient across the airplane insulation blanket as well as a thermoelectric device exposed to a thermal gradient between any two aircraft structures. 
         [0029]    Another sensor/transmitter configuration  300  is illustrated in  FIG. 5 . In this configuration, when the door  301  is opened or closed, the state of the micro-switch  302  changes as the land  303  is separated from the micro-switch  302 . With the micro-switch  302  connected to input pins of the sensor/transmitter  304 , a switching of the micro-switch  302  causes the sensor/transmitter  304  to transmit a data packet consistent with the new state of the micro-switch  302 . Alternately, the micro-switch  302  may be connected to the sensor input pins of the sensor/transmitter  304  that are sampled, for example, once per second. In this configuration, the sensor/transmitter  304  transmits the relevant message whenever the state of these input pins is changed. The sensor/transmitter  304  is powered by an energy harvesting device, for example, a solar cell  306  as described above. One sensor/transmitter  304  embodiment is capable of storing over 100 hours of operation time in its on-board capacitors. In another configuration, rather than a micro-switch  302 , the sensor/transmitter  304  is configured with a magnetic reed relay, and the land  303  of the door includes a small magnet bonded thereto such that movement of the door  301  in opening and closing causes a change in the electrical state of the magnetic reed relay. 
         [0030]    With respect to  FIGS. 3 ,  4 , and  5 , those skilled in the art will understand that embodiments exist where a photovoltaic cell and an ambient light source are incorporated, rather than the described “mechanical” triggering devices. In such an embodiment, the photovoltaic cell might be mounted so that the light impinges it when a door is opened. One example is a small cutout area and a door jamb. No matter what physical configuration is incorporated, each of the above described sensor/transmitters, when deployed as part of a system is configured with a unique identification number that is included in its transmitted data packet to allow the system to distinguish between sensor/transmitters and associated sensor locations. Through the use of energy harvesting, sensor/transmitters do not require any airplane wiring thereby making them light weight and easy to install. Further, no airplane power or data wiring is required for their normal operation and such devices are virtually maintenance free. 
         [0031]      FIG. 6  is a schematic view of a mechanically powered seat sensor assembly  400 . Seat sensor assembly  400  is a mechanically-powered wireless seat sensor and transmitter. Generally, the principles of the various mechanically powered wireless door sensor/transmitters described above are also applied to the sensing of full removal, partial removal, movement, and installation of seat cushions  402  from aircraft seat frames  404 . In this embodiment, the mechanical energy harvester  410  is “triggered” by the work of installing or removing the seat cushion  402  from the aircraft seat frame  404 , thus causing a signal to be transmitted every time the seat cushion  402  is installed and/or removed. 
         [0032]    In the illustrated embodiment of the mechanical energy harvester  410 , a flexible lever  412  is attached to the seat pan  414  typically under the seat cushion  402 . Installation of the cushion  402  presses the lever  412  down, causing land number one  416  of lever  412  to engage a spring loaded lever  418  and activate a mechanical energy harvesting device within a wireless sensor/transmitter  420  causing it to transmit. Land number two  422  of lever  412  is configured to rest on the top  424  of the sensor/transmitter  420  to carry vertical loads through to the seat pan  414 . 
         [0033]    Upon removal of the seat cushion  402 , flexible lever  412  will rebound, thus releasing the spring loaded lever  418 . Release of the spring loaded lever  418  activates a mechanical energy harvesting device within wireless sensor/transmitter  420  causing it to transmit. 
         [0034]      FIG. 7  is a schematic view of a vibration powered seat sensor assembly  450 . Seat sensor assembly  450  is a vibration powered seat cushion wireless sensor and transmitter. The principles of the photovoltaic powered light bezel wireless sensor/transmitter described above with respect to light assembly  100  are applied to sensing full removal, partial removal, and installation of seat cushions  402  from aircraft seats  404 , except that in this embodiment, the photovoltaic cell is replaced by one or more vibration harvesters  452  installed in the passenger seat pan  454 . In various embodiments, the vibration harvester  452  may include a cantilevered piezoelectric beam or electro-dynamic harvester, such that seat vibration is converted to electrical power, which is used to charge a battery or capacitor. A voltage rectification circuit may be incorporated to convert alternating current generated from such devices into direct current that is then utilized to maintain a charge on a battery or capacitor. A low-power wireless sensor, described further in the following paragraph, is utilized to transmit an identification number whenever a state of the sensor changes (e.g. closed circuit changes to open circuit, and visa versa). The illustrated embodiment illustrates two separate vibration harvesting units  452  that include the described sensors and transmitters. In one embodiment, vibration harvesting units  452  located at each corner of the seat pan  454  provides an indication that the cushion  402  has been partially or fully removed. 
         [0035]    One sensor configuration is illustrated in  FIG. 7 . In the illustrated embodiment, a membrane switch  460  is attached to the seat pan  454 . The membrane switch  460  includes a pliable plunger  462 , which, when pressure is applied, closes a micro-switch  464 , thus indicating that pressure (typically from the seat cushion  402 ) is applied at that location. A housing  466  holds the micro-switch  464  and is attached to the seat pan  454  utilizing fasteners  468  that also pass through the plunger  462  as shown. Such a configuration allows relatively small forces from the seat cushion  402  to be detected while maintaining a low profile above the seat pan  454 , thus avoiding hard-points from being transmitted through the cushion  402  to the passenger. Additional seat cushion sensor configurations are contemplated. In one embodiment, the sensor/transmitter and energy storage device are all within the micro-switch unit  464 . In alternative embodiments, the energy storage device and sensor/transmitter can be located anywhere on the seat, though locating the devices on or near the seat pan are considered to be advantageous. In one specific embodiment, all four corner sensors (e.g., membrane switches  460 ) within a seat configuration are connected to a single sensor/transmitter unit and/or a single energy storage unit. 
         [0036]      FIG. 8  is a schematic view of a return air grill sensor assembly  500 . In the illustrated embodiment, return air grill sensor assembly  500  is a thermoelectric powered return air grill wireless sensor and transmitter. 
         [0037]    The principles of the photovoltaic powered light bezel wireless sensor/transmitter described above with respect to light assembly  100  are applied to sensing full removal, partial removal, and installation of cabin return air grills  502  from aircraft cabin side walls  504 , except that in this embodiment, the photovoltaic cell is replaced by a thermoelectric generator  506  to provide electrical energy. In the illustrated embodiment, the thermoelectric generator  506  is located within an airplane structure behind or nearby the return air grill  502 . The return air is utilized by the thermoelectric generator  506  to charge a battery or capacitor that is located within a transmitter/storage device  508 . Transmissions from transmitter/storage device  508  include, for example, a unique identification number for the transmitter and an indication of whether the return air grill  502  is “installed” or “removed” from the cabin side wall  504 . 
         [0038]    One or more sensors  510  are used to detect when the return air grill  502  is installed, removed or partially removed and such an event results in a transmission being sent by the transmitter/storage device  508 . In one embodiment, a magnetic reed switch may be used with, for example, a magnet bonded to the return air grill  502  and a magnetic reed switch mounted on an exterior  512  of the cabin side wall  504  such that the magnet causes the reed switch to close while the return air grill  502  is installed at that location. In the illustrated embodiment, the transmitter/storage device  508  is also mounted to the exterior  512  of the cabin side wall  504 . A micro-switch may also be used as a sensor. 
         [0039]    As illustrated, the thermoelectric generator  506  and a related heat sink  520  are mounted to a crease beam  530  that lies between two sections of insulation  532 ,  534  and that is mounted to an interior  540  of the aircraft outer layer  542 . Thus, the thermoelectric generator  506  is able to generate electrical power for charging transmitter/storage device  508  from the thermal gradient between the generally warmer return air and the crease beam  506 , which is generally colder during flight. Return air grill sensor assembly  500  is operable to allow a wireless transmission to be sent whenever a return air grill  502  is installed, removed or partially removed from the cabin side wall. Though the return air grill is located near the cabin floor  544 , it is understood that such grills may be located in other places within an aircraft cabin. 
         [0040]    With respect to all of the above described embodiments, a unique transmitter identification number is included in each wireless transmission. The unique transmitter identification number is correlated to the sensor&#39;s physical location. Therefore, transmissions from these sensors may be correlated to the associated physical locations. In one embodiment, a report may be generated that provides a listing of all physical locations where a transmission originated due to, for example, movement of a light bezel, or operation of an access door. In addition, the transmissions may be date/time stamped at the receiver with this information included with the report. As a result of such a report, only inspection in the specific physical locations listed in the report may be required, while other locations might not require such an inspection. To provide such a report, a database of sensor identification numbers and corresponding physical location is constructed and maintained, for example, at an airplane level. In addition, it should be noted that all of the above described sensor/transmitter embodiments may be incorporated in configurations where multiple sensors are interfaced to a single transmitter and/or a single energy storage device. 
         [0041]    In addition, the above described transmitter devices, which generally are powered by photovoltaic cells, thermoelectric, and/or vibration are also programmed, in certain embodiments, to occasionally transmit a “sign of life” indication, which is useful in maintaining an accurate database of sensors and transmitters and ensuring that the many transmitters that may be implemented on an aircraft are all operational. The transmitters above may also transmit other prognostic information for diagnostic purposes, including, but not limited to, an energy state of on-board energy storage devices (e.g. min/max/average/current battery capacity or capacitor voltage), a state of photovoltaic cells (min/max/average/current voltage), checksum, and a wireless signal strength. 
         [0042]    The energy harvesting features and low power configurations described herein provide installation capabilities where no data wiring, power wiring and primary batteries are required. Such configurations result in light weight installations that are relatively easy to install, simple to retrofit, and easily maintained. Another important point about the wireless, energy harvesting designs described herein is that such systems do not need to be wired into airplane power. The installation of the above described solutions enable an airline to install the sensing and monitoring devices in locations that may not have a readily available power source. Finally, methods of sensing that do not employ energy harvesting may be considered too costly or time consuming for airlines to implement. 
         [0043]    It should also be noted that the above examples only, and that any of the described sensing mechanisms could be incorporated in any of the monitoring locations. For example, while the light bezel monitoring device is described as using a photovoltaic device, it is also possible to monitor the open/closed status of the bezel utilizing the above described piezoelectric device that is caused to deflect or vibrate by mechanical work, in this case the movement of the lighting bezel, thus producing an electrical charge in piezoelectric materials. 
         [0044]    The embodiments are further intended to increase the efficiency of the above described inspection processes. In one example, those locations that have transmitted information indicated that some type of tampering has occurred, such as the opening of a light bezel or the removal of a return air grill, are the only locations subject to an extensive physical inspection before continued operation of the aircraft. Other locations may only need a periodic, cursory or visual inspection, thereby reducing the number of man-hours needed to fulfill search and inspection requirements. 
         [0045]    While the above described embodiments are generally described in the context of employing energy harvesting devices for electrical power, it is also contemplated that embodiments of the described sensor/transmitter devices may utilize one or more primary batteries instead of, or in addition to, the energy harvesting capabilities. 
         [0046]    Finally, while the described embodiments relate specifically to the energy harvesting techniques and the sensing of conditions, and the transmission of those conditions, it follows that certain embodiments include one or more receiving systems operable to receive the transmission from the sensor/transmitter, and that such a system is operable to record, store, and compile the data received from the transmitters. In one embodiment, the receiving system is operable to track the transmitters to ensure that they are active, and generate an indication if a transmitter is determined to be inactive. In such embodiments, a date and time stamp is generated by the receiving system. In conjunction with the receiving system, a user interface is contemplated from which a user can read, print, send, and/or relay the relevant sensor transmitter information as well as capture the resolution of the event(s) for a robust and traceable history. 
         [0047]    While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.