Abstract:
A sensor network for managing the location of materials on a construction site includes RF sensors having unique identifiers attached to selected items. A radio frequency sensor reader network with two or more RF sensor readers sense the unique identifier of each of the radio frequency sensors and their distance from each radio frequency sensor. A processor connected to the radio frequency sensor reader network determines the location of the radio frequency sensors based on the unique identifier and distance sensed by each radio frequency sensor reader. A selection device for selects a RF sensor based on a user input, and an image capture device moves in response to the user input to display the selected radio frequency sensor on a display device.

Description:
FIELD 
       [0001]    Sensor networks for managing the location of materials on a construction site. 
       BACKGROUND 
       [0002]    Construction and project sites are continually evolving in terms of buildings being constructed, material areas moving, project offices expanding and so on. With these constant changes, project sites typically don&#39;t have permanent power networks, but rely on gas-powered generators or other temporary means of supplying power to areas that require it. 
         [0003]    In today&#39;s world of construction, material handling is becoming a more automated process in terms of receiving material, finding the location of material and creating progress reports based on the flow of materials. This automated process involves attaching RF sensors to each piece of material so that all the critical material is assigned a unique ID number allowing for automated location finding. In order to read the sensor tags, a local network of RF sensor readers must be installed on the construction site. As material is delivered to the construction site and then laid down in storage areas, the sensor networks must be in range of the sensor tags to locate the position of the material. These laydown areas typically do not have easy access to power to run the optical robotics and RF sensor readers. The other issue is that as the construction site evolves, laydown areas move, requiring the sensor networks to move with the laydown areas, or expand in size as they do. 
       SUMMARY 
       [0004]    According to an aspect, there is provided a sensor network for managing the location of materials on a construction site. There are a plurality of radio frequency sensors having unique identifiers and attachments for attaching the radio frequency sensors to selected items. There is a radio frequency sensor reader network comprising two or more radio frequency sensor readers. At least two radio frequency sensor readers sensing the unique identifier of each of the radio frequency sensors and the distance from the radio frequency sensor reader to each radio frequency sensor. A processor is connected to the radio frequency sensor reader network for determining the location of at least one radio frequency sensor based on the unique identifier and distance sensed by each radio frequency sensor reader. A selection device selects a radio frequency sensor based on a user input. There is at least one image capture device that has a movable field of view. The field of view moves in response to the user input into the selection device and the corresponding location calculated by the processor to include the selected radio frequency sensor. A display device is connected to the image capture device for displaying the field of view of the image capture device. 
         [0005]    According to an aspect, there is provided a method of managing the location of materials on a construction site. The method comprises the steps of: providing a radio frequency network comprising two or more radio frequency sensors; attaching a radio frequency tag having a unique identifier to each item on the construction site to be managed; sensing the unique identifier of at least one radio frequency tag by at least two radio frequency sensors and the distance of the at least one radio frequency tag to each of the at least two radio frequency sensors; calculating a location for each sensed radio frequency tag based on the unique identifier and distance information sensed by the radio frequency sensors; selecting a unique identifier processed by the processor; moving the field of view of an image capture device having a movable field of view to the selected radio frequency tag; and displaying the field of view of the image capture device on a display device. 
         [0006]    According to an aspect, when project materials and equipment need to be tracked to a precise location on the project site, radio frequency (RF) sensor networks are provided in areas of the site where materials are stored. The RF sensor network determines the precise location of construction material by using triangularization algorithms. The robotic optical sensors automatically pan and zoom to the location of the materials (as determined by the RF sensors), to help material coordinators and construction managers quickly identify what the material is and where it is located. The sensor networks incorporate the use of an automated robotic camera that can pan, tilt and zoom directly into the material of interest. To power the network of RF and optical sensors, solar power is used within the design of the sensor network. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    These and other features will become more apparent from the following description in which reference is made to the appended drawings, the drawings are for the purpose of illustration only and are not intended to be in any way limiting, wherein: 
           [0008]      FIG. 1  is a schematic view of a sensor network on a construction site. 
       
    
    
     DETAILED DESCRIPTION 
       [0009]    A sensor network generally identified by reference numeral  10 , will now be described with reference to  FIG. 1 . 
       Structure and Relationship of Parts: 
       [0010]    Sensor network  10  is comprised of individual stations  12  that relay data between them by use of a wireless mesh network. Sensor network  10  is made up of two or more of the individual stations  12 , and preferably three or more stations  12 , depending on the algorithms used, communicating with each other to locate an item  14 . In order to do this, each station  12  has a radio frequency (RF) sensor reader  15  and each item  14  to be tracked or located has a RF sensor  18  attached, which contains a unique identification number. RF sensors  18  may be attached using any practical means, such as adhesive, tie strap, pin connection, etc. 
         [0011]    In the depicted embodiment, items  14  are metal beams in the middle of a laydown area  16  being monitored by stations  12 . The laydown area  16  may be defined by one or more geofences to mark off the area and specific zones within the area for computing and sensing purposes. Each metal beam  14  has a RF sensor  18  attached, which contains a unique identification number. RF sensor readers  15  are used to detect the unique identification number of each RF sensor  18  within the geofence, or laydown area  16 . RF sensor readers  15  are also used to determine the distance between each item  14  and the respective RF sensor reader  15 . For example, this may be done by analyzing the received signal strength, TDOA (time difference of arrival), angle of arrival, or other techniques. Using these distances, it then becomes possible to determine the position of each metal beam  14 . Clearly, if triangulation techniques are used, three or more sensor readers  15  will be required, as in the preferred embodiment. 
         [0012]    An image capture device  30  is provided that has a movable field of view. In one embodiment, this is a digital camera mounted on a position-controllable mounting such that camera  30  can be remotely controlled to adjust its pan, tilt and zoom to view an object or area of interest. Camera  30  may display a real-time image, or it may take pictures at specified intervals. There may be a camera  30  on each station  14 , or there may be one camera  30  for the entire network  12 . Preferably there are multiple cameras  30  to improve the viewing options. As depicted, camera  30  and RF sensor reader  15  are housed in the same component. 
         [0013]    The calculations used to calculate the location of each item  14  are done by a processor, such as a processor in a computer  20 . Computer  20  is connected into the wireless mesh network, either by a direct connection to one of the stations  14 , or by a wireless link. Computer  20  also has an input device  22 , such as a keyboard, mouse, touch screen, etc., and a display device  24 , such as a monitor. In one embodiment, the processor is a component in a CPU  26 , which also contains a database in a memory unit for storing the information measured by RF sensor readers  15  and calculated by the processor. When input device  24  receives an input, CPU  26  directs camera  30  to find the selected item  14  within its field of view based on the coordinates calculated by the processor. This allows for visual identification of construction materials and equipment, including its accessibility, position, and asset type. 
         [0014]    In addition to being directed toward items  14 , camera  30  may also perform other functions. For example, camera  30  be manually controlled, or it may be directed toward specific areas. For example, within laydown zone  16 , a user may configure additional geofences, such that camera  30  may be directed to pan and zoom to one of the zones defined by the geofences. Computer  20  may also be programmed to direct camera  30  toward a specific RF sensor  18  when a predefined geospatial event occurs, such as crossing a geofence or changing position. 
         [0015]    It will be understood that many difference computer architectures may be used to accomplish the same goals, including integration into existing networks and systems. For example, computer  20  may be a server used for processing and routing of information on an Ethernet network. 
         [0016]    In order to solve the issues of building a sensor network without access to permanent power, the sensor network needs alternative power systems. As depicted each station  12  includes a solar panel  32 . 
         [0017]    In addition to solving the needs for a portable system, the individual stations of the network are built so that forklifts can easily move them around or they move themselves via tracks, electric motors and wheels (not shown). As stations  12  and thus network  10  is intended to be mobile, network  10  is preferably configured to self-calibrate when base stations  12  are placed in new locations by using software to determine the current position of base stations  12  and a map of the area being monitoring. Network  12  may also be configured to communicate the position of items  14  being tracked within the radio frequency communication range of the reader network, such that the information may be read by a portable electronic device. 
       Operation: 
       [0018]    Sensor network  10  is arranged by positioning base stations  12 , which are configured with cameras  30 , RF sensor readers  15 , solar panels  32 , and are configured for wireless communication. A laydown site  16  is defined, and radio frequency sensors  18  are attached to items  14  to be tracked. In a preferred embodiment, sensor network  10  is allowed to self-configure to detect the position of each RF sensor reader  15  and possibly the environment. RF sensor readers  15  are then used to detect the unique identifier of each RF sensor  18 , as well as the distance, such that the position of each item  14  can be determined. This is calculated by a processor in a computer  20 , which may also be used to received commands from users via input device  22  to redirect the field of view of camera  30  to display certain items  14  on monitor  24 . Preferably, the various components on base stations  14  are powered by solar panels  32 . 
         [0019]    The computer  20  or another computer, may be programmed to track the movement of items  14  as the status or location of RF sensor  18  changes. For example, the computer may be programmed to cause an alert to be activated if an item  14  is moved, or moved over a geofence. This may include causing one of the cameras  30  to track item  14  as it moves. 
       Advantages: 
       [0020]    An individual solar powered sensor station is designed to fulfill a number or requirements including:
       Mobile—the units can move themselves via tracks, electric motors and wheels or can easily be moved with construction machinery.   Continuous operation year round without using line voltage   Use of sophisticated software that provides a geospatial understanding of its environment.       
 
         [0024]    The individual solar powered stations  12  are also able to complete a number of functions to help automate material handling, including:
       RF sensor equipment to locate the position of an RF sensor attached to construction material or equipment   Robotic optical camera to zoom or pan directly into the position of the material for visual inspection remotely   Wireless Ethernet communications to send optical and sensor data back to a central server  20  for processing and routing.       
 
         [0028]    In this patent document, the word “comprising” is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements. 
         [0029]    The following claims are to be understood to include what is specifically illustrated and described above, what is conceptually equivalent, and what can be obviously substituted. Those skilled in the art will appreciate that various adaptations and modifications of the described embodiments can be configured without departing from the scope of the claims. The illustrated embodiments have been set forth only as examples and should not be taken as limiting the invention. It is to be understood that, within the scope of the following claims, the invention may be practiced other than as specifically illustrated and described.