Patent Application
20050116821
The invention relates generally to asset tracking. More particularly, the invention relates to a system and method for tracking assets based on an optical communications imager and optical tags attached to each asset to be tracked.
The location and status of assets can be determined using different means of asset tracking. For example, equipment, inventory and personnel can be tracked so that their position and status can be determined at different times. One common type of asset tracking is based on barcodes attached to the assets. The barcodes are examined with a barcode reader or scanner. Another type of asset tracking is based on passive radio frequency identification (RFID) tags attached to the assets. The RFID tags are read using a radio frequency (RF) interrogation device. According to either type of asset tracking, assets are tracked as they pass by checkpoints equipped with the appropriate readers. Checkpoints are frequently installed at shipping and receiving locations, and at entry and exit locations such as doorways. Such passive systems can determine where an asset is at discrete times but not where the asset is at any moment.
More recently, real-time locating systems (RTLSs) have been developed that use a network of sensors to determine the location and status of an asset in real-time. An RTLS has many advantages, including reducing inventory and improving employee productivity because items and personnel can be located quickly. Other benefits include a reduction in the time spent locating equipment for maintenance, upgrade or inventory review; a reduction or elimination of items that are lost, stolen or hoarded; and a security benefit realized by allowing or prohibiting tagged items or personnel entry into or exit from controlled areas. Current RF based RTLSs require that an RF transmitter be attached to each asset to be tracked. Multiple receivers are used to listen for any transmitters that are within reception range and record the transmitted data. Using this information, the identity of an asset is determined and the position of the asset is established by triangulation. A software based system can be used to track the asset as it changes location.
RF based RTLSs have inherent disadvantages. Electromagnetic interference (EMI) generated by equipment such as welders, electric motors and other machinery can hinder tracking capability. Conversely, EMI generated by RF communications of an RTLS can interfere with sensitive equipment such as computer controlled machinery and health care equipment. In addition, because RTLSs typically operate in unlicensed frequency bands, various wireless communications that increasingly clutter these frequency bands can interfere with RTLS operations. Furthermore, RTLS communications generate RF signals which can penetrate unshielded buildings and enclosures. Thus security is at risk because valuable information such as inventory levels can be ascertained by outside observers monitoring the RF signals.
What is needed is an asset tracking system that can monitor the location of an asset any time. The asset tracking system should be immune to EMI generated in electrically noisy environments. In addition, the asset tracking system should not be susceptible to eavesdropping. The present invention satisfies these needs and provides additional advantages.
In one aspect the invention features an optical asset tracking system including a sensor having a plurality of pixels and a sensor processor in communication with the sensor. Each pixel is configured to generate an electrical signal in response to an optical data signal emitted by an optical tag and incident on the pixel. The sensor processor is configured to generate an electrical data signal representative of the optical data signal incident on each pixel. The sensor processor generates asset data responsive to the electrical data signal for each pixel.
In one embodiment each pixel is configured to provide a communications data signal in response to the optical data signal emitted by the optical tag and incident on the pixel. In another embodiment the sensor and the sensor processor includes an optical communication imager. In another embodiment the sensor includes an analog video camera in communication with a frame grabber. In still another embodiment the sensor includes a digital video camera. In yet another embodiment the optical asset tracking system also includes an optical tag database in communication with the sensor processor. The optical tag database stores asset data for each of a plurality of optical tags. In another embodiment the optical asset tracking system also includes a tracking processor in communication with the sensor processor.
In another aspect the invention features a method for real-time location of an asset having an optical tag. The method includes emitting an optical data signal from the optical tag and detecting, at a sensor having a plurality of pixels, the optical data signal at one or more of the pixels. The optical data signal includes asset data. The method also includes determining the asset data in response to the detected optical signal. In one embodiment the method also includes determining the location of the asset in response to a determination of which one or more pixels detected the optical data signal. In another embodiment the method also includes detecting an interrogation signal at the optical tag and performing the step of emitting the optical data signal in response to the detection of the interrogation signal.
In another aspect the invention features an optical asset tracking system including a plurality of sensor processors each in communication with a respective one of a plurality of sensors. Each of the sensors has a plurality of pixels with each pixel configured to generate an electrical signal in response to an optical data signal emitted by an optical tag and incident on the pixel. Each sensor processor is configured to provide asset data in response to the communications data from the respective sensor. In one embodiment the optical asset tracking system also includes a tracking processor in communication with the sensor processor through a communications network. In a further embodiment the optical asset tracking system also includes an optical tag database in communication with the tracking processor. The optical tag database stores asset data for each of a plurality of optical tags. In another embodiment the optical asset tracking system also includes a plurality of tracking processors each in communication with a respective one of the sensor processors.
In another aspect the invention features an optical tag for generating an optical data signal including asset data. The optical tag includes an optical modulator, a memory module for storing asset data, and a tag processor in electrical communication with the optical modulator and the memory module. The tag processor generates a data signal in response to the asset data and the optical modulator generates an optical data signal in response to the data signal. In one embodiment the optical tag also includes an environmental sensor in electrical communication with the tag processor. In another embodiment the optical tag also includes a control circuit in electrical communication with the tag processor and the optical modulator. The control circuit provides a control signal in response to the data signal. In a further embodiment the optical tag also includes a trigger sensor to detect an interrogation signal. The trigger sensor is in communication with the tag processor and the control signal is responsive to the detection of the interrogation signal at the trigger sensor.
The above and further advantages of this invention may be better understood by referring to the following description in conjunction with the accompanying drawings, in which like numerals indicate like structural elements and features in the various figures. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.
A tracking processor 42 embedded in a host computer 46 communicates with the sensor processor 38 to receive the pixel data. The host computer 46 can be local to the optical communications imager 22 or it can be at a remote location, such as a different room or building. The tracking processor 42 determines the asset data and asset location information for each asset 14 in the field of view of the optical communications imager 22, and generates asset tracking information. The sensor processor 38 and the tracking processor 42 can be implemented in any device or circuitry used to process data to achieve the desired functionality. In one embodiment the sensor processor 38 and the tracking processor 42 are integrated as a single processor providing both sensor and tracking functionality. In other embodiments the sensor processor 38 and the tracking processor 42 are implemented as dedicated electronic circuits.
A tag tracking database 48 keeps track of the current location and status of each tag used in the optical asset tracking system 10. Asset locations recorded in the tracking database 48 can be retrieved to determine where the asset 14 was located at various times. Environmental conditions and aging information can be recorded so that any assets 14 having limited usefulness based on environmental exposure or age can be located and used before similar assets 14 having a longer lifetime. The tracking database 48 can be queried to quickly determine the location of an asset 14 having infrequent utilization. In one embodiment asset data stored in the tag tracking database 48 is referenced to corresponding video data generated by the optical communication imager. For example, an individual tampering with an asset 14 can be viewed on video with corresponding asset data overlaid on the video display.
In other embodiments of the optical asset tracking system 10, the tracking functionality is integrated with the optical communications imager 22. For example, asset identification can be performed by a processor co-located with the optical communications imager 22. Additionally, an integrated alarm can be activated in response to assets 14 being moved within or removed from the monitored area 30.
An important difference between the sensor 34 for the optical communications imager 22 and the sensor 34′ fabricated from commercially-available components is that the communications data rate of the latter is limited to the frame rate of the camera 36. More specifically, the camera 36 does not provide communications data in the conventional sense; however, a single pixel can support communications for data rates that do not exceed the frame rate. Thus the communications data rate is less by orders of magnitude. In applications where data transfer between assets 14 and the sensor 34 are low, the asset tracking system 10′ constructed from commercial components is preferred based on its substantially lower cost.
Advantageously, the optical asset tracking system 10 of the invention is not affected by electromagnetic interference (EMI) sources, such as electric motors and machinery, because optical signals are utilized. Furthermore, the data transmitted from the optical tags 18 is not vulnerable to eavesdropping by parties outside the room or building in which the assets 14 are located.
The asset data and tracking information generated by the optical asset tracking system 10 can be shared with other resources such as enterprise management tools and planning systems, and the asset tracking data can be used for a wide range of purposes. By way of example, assets 14 that can be tracked include factory equipment, vehicles, valuable items, employees, hospital patients and the like. Employees can be tracked by attaching an optical tag to a badge worn on the employee's clothing. Room lights, electrical power, automatic doors, safety equipment, security equipment and utilities can be activated or deactivated according to the location of the employee. Similarly, optical tags can be attached to hospital patients using wrist bands, badges and the like. Alternatively, an optical tag can be integrated into a bandage that can be affixed directly to the skin. The optical tag can record the health status, health history and medical treatment history of the patients. Items having critical time and environmental sensitivity, such as human organs and blood, can be tracked. For example, a human organ can be tracked from its point of harvest to its point of insertion. Environmental sensors can be attached to the organ carrier to record environmental parameters during transport. The recorded data can be broadcast during transport to confirm that the organ is not exposed to unsatisfactory conditions.
Optical broadcast of the recorded information may be continuous or can be initiated in response to an interrogation signal received by the optical tag. Alternatively, periodic or continuous broadcast of general patient information can occur with detailed patient information being broadcast in response to the interrogation signal. In one example, the optical tag includes one or more sensors to monitor a physical parameter associated with the health of the patient. If it is determined that a physical parameter crosses an associated threshold value, the optical tag automatically initiates a broadcast of patient information to the optical communications imager 22. In another example, devices having critical maintenance schedules or usage limitations can be tracked. For example, a blood distribution unit can be interrogated to determine its use history and current delivery rate.
Each optical communications imager 22 observes a monitored area 30 (see
Optical tags 18 can take on a variety of forms. For example, an optical tag 18 can include an optical source that includes an LED or a laser that emits an optical signal at regular intervals. If it is important to constantly monitor the location of the assets 14, the optical source continuously emits the optical signal. In one embodiment the optical tag 18 includes a tag processor, a memory module and one or more sensors to monitor environmental parameters (e.g., temperature and g-forces). The memory module stores the data generated by the sensor. Broadcasts of optical data can include raw sensor data and processed sensor data, such as the minimum, maximum and average of one or more of the parameter values determined after the previous broadcast. In another embodiment the memory is provided by the asset 14. The data stored in the asset memory is provided to the optical tag 18 through an interface module (e.g., RS/232, I2C, USB, Ethernet or Firewire) on the asset 14. Thus the optical tag 18 serves as a communication relay between the asset 14 and the host system 46 and database 48.
Broadcasts of asset data can be periodic or continuous, as described above, or broadcasts can be initiated on-demand. Periodic and on-demand broadcasting are preferred over continuous broadcasting in many applications to improve battery life. In an example of on-demand broadcasting, asset data is transmitted by manually activating a switch or button on the optical tag 18. Alternatively, the optical tag 18 includes an RF sensor, optical detector or acoustic sensor to receive an RF interrogation signal, optical interrogation signal or acoustical interrogation signal, respectively. In one embodiment the interrogation signal includes security data which is examined by the optical tag 18 to ensure the validity of the interrogation request. The optical tag 18 initiates a broadcast upon detection of the interrogation signal. In another embodiment broadcasting is triggered when an environmental condition is changed or crosses a predetermined threshold value. For example, broadcasting can be initiated when movement of the asset is detected, when the ambient temperature increases (or decreases) to a predetermined temperature or when acoustic noise exceeds a predetermined level.
Asset data broadcasts can be automatically initiated. For example, if a tag processor determines that one of the monitored environmental parameters exceeds a threshold value, an immediate broadcast of the asset data is initiated. In another example, a motion detector integrated with the optical tag 18 initiates broadcasting if the asset 14 moves.
The information content broadcast by the optical tag 18 can vary. For example, an optical tag 18 can broadcast a limited data set at one broadcast interval and a larger data set at a longer broadcast interval. In another example, the optical tag 18 broadcasts limited data at regular intervals and detailed data for on-demand broadcasts or when a monitored parameter crosses a threshold.
In an alternative embodiment the LED 126, resistive component 130 and FET 134 shown in
While the invention has been shown and described with reference to specific preferred embodiments, it should be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the following claims.
