Abstract:
A visual display is provided through the combined effect of many devices that individually illuminate in response to wind flow. The devices are distributed at different locations within a three-dimensional space, so as to provide an overall illumination effect throughout the space that visually indicates wind (air) or other fluid flowing through the space. Each device can include a housing, at least one light source, a sensor system, and a device controller. The sensor system can include any of various types of sensor subsystems, each having one or more sensors, but includes at least a flow sensor subsystem. The device controller is configured to activate the light source in response to the sensor system detecting a change in an environmentally-related input, such as air flow, sensed by the sensor system.

Description:
BACKGROUND 
     Illuminated large-scale displays that comprise a large number of individual illuminated elements may serve as works of art or to convey information. A stadium display is an example of a large-scale display that can convey both information and artistic visuals. Another type of large-scale display involves a system in which each person in a crowd holds an illumination device that can be wirelessly remotely controlled from a centralized controller. Such a system can be used to provide interesting visual effects using spectators in a darkened stadium or arena as “pixels” of a large-scale display. In another known system, a field of wall-mounted elements can be individually activated by infrared radiation, such as by shining a flashlight on them. In still another known system, a metal sculpture includes individual illumination elements resembling blades of grass that can be activated by air movement, such as a person blowing on them. 
     SUMMARY 
     Embodiments of the present invention relate to a flow sensing system and method for providing a display that individually illuminates a multiplicity of devices in response to environmental flow. In an exemplary embodiment, the flow sensing system includes a multiplicity of devices distributed at different locations within a three-dimensional space, so as to provide an overall illumination effect throughout the space that visually indicates wind (air) or other fluid flowing through the space. Each device can include a housing, at least one light source, a sensor system, and a device controller. The sensor system can include any of various types of sensor subsystems, each having one or more sensors, but includes at least a flow sensor subsystem. The device controller is configured to activate the light source in response to the sensor system detecting a change in an environmentally-related input, such as air flow, sensed by the sensor system. 
     Other systems, methods, features, and advantages of the invention will be or become apparent to one of skill in the art to which the invention relates upon examination of the following figures and detailed description. All such additional systems, methods, features, and advantages are encompassed by this description and the accompanying claims. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The invention can be better understood with reference to the following figures. The elements shown in the figures are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the invention. Also, in the figures like reference numerals designate corresponding elements throughout the different views. 
         FIG. 1  illustrates a system in which a multiplicity of devices that can illuminate in response to sensed environmentally-related inputs are distributed throughout a tree, in accordance with an exemplary embodiment of the invention. 
         FIG. 2A  is a perspective view of one of the devices shown in  FIG. 1 , in accordance with the exemplary embodiment. 
         FIG. 2B  is a bottom view of the device of  FIG. 2A . 
         FIG. 3  is a block diagram of the device of  FIGS. 2A-B , in accordance with the exemplary embodiment. 
         FIG. 4  is a flow diagram illustrating a method of operation of the system of  FIG. 1 , in accordance with the exemplary embodiment. 
         FIG. 5  is similar to  FIG. 5 , illustrating a method in further detail, in accordance with the exemplary embodiment. 
         FIG. 6  illustrates the devices of  FIG. 1  in wireless communication with each other and a central controller, in accordance with the exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     As illustrated in  FIG. 1 , in accordance with an illustrative or exemplary embodiment of the invention, a portion of a system  10  can include a multiplicity of devices  12  distributed at different locations within a three-dimensional space, such as the space occupied by the upper regions of a tree  14 . The term “multiplicity” is used herein to refer to a quantity that is substantially greater than a plurality. As described below, the display of light produced by the multiplicity of devices  12  is somewhat analogous to a display of light produced by a multiplicity of pixels of an electronic display screen. That is, each of the devices  12  produces a pixel-like display of light that, in combination with the displays produced by all other devices  12  of the multiplicity, provides an overall effect to an observer  16  that is somewhat analogous to the effect of an electronic display screen that comprises a multiplicity of pixels. For purposes of clarity in  FIG. 1 , not all devices  12  of the multiplicity are shown. Note that  FIG. 1  is not to scale. 
     Although in the exemplary embodiment the three-dimensional space in which devices  12  are distributed is the space occupied by the upper regions of tree  14 , in other embodiments the three-dimensional space in which such devices are distributed can be any other suitable space or region. For example, in another embodiment the devices (not shown) can be distributed in the space occupied by a mechanical support structure (not shown). In still other embodiments the devices (not shown) can be distributed by attaching them to various different supports or structures within a three-dimensional space or region. 
     As illustrated in  FIGS. 2A-B , in the exemplary embodiment each device  12  can include a housing  18 , a light source  20  (only an exterior portion of which is shown in  FIGS. 2A-B ) coupled to housing  18 , a sensor system  22  (only an exterior portion of which is shown in  FIGS. 2A-B ) coupled to housing  18 , and an attachment member  24  for attaching device  12  to a tree branch  26  or other supporting structure. Device  12  can be of any suitable size. Although in the exemplary embodiment attachment member  24  has a hook-like end that can be placed over a tree branch, in other embodiments the attachment member can have a clamp (not shown) or any other suitable means for attaching the device to a tree branch, support, or other structure. 
     Openings  28 ,  29 ,  31  and  30  in housing  18  define portions of sensor system  22  for allowing air to flow through housing  18  in three mutually orthogonal directions. Although not shown for purposes of clarity, corresponding openings are located opposite openings  28  and  29  so that air can flow horizontally through housing  18 . Likewise, openings  30  and  31  are located at opposite ends of housing  18  so that air can flow vertically through housing  18 . Other portions of sensor system  22 , which are not shown in  FIG. 1  but located inside housing  18 , can monitor for and detect a change in air flow entering housing  18  in horizontal directions  32  and  34  or in a vertical direction  35 . (Although not indicated in  FIGS. 2A-B , air can also flow through housing  18  in directions opposite those indicated by the arrows.) As a typical gust of wind may include components in two or more directions, such components may flow into housing  18  from more than one direction. It should be understood that the shapes, relative dimensions and arrangements of housing  18  and other elements of device  12  described above are intended only to be illustrative or exemplary. 
     As illustrated in  FIG. 3 , internal elements of device  12  can further include a device controller  36 , a power supply  38 , and a wireless communication system  40 . Although not shown for purposes of clarity, power supply  38  can include a battery mounted within housing  18  and a solar panel mounted on housing  18  for recharging the battery during daylight. Also, although for purposes of clarity power supply  38  is shown connected to only device controller  36 , power supply  38  is also coupled to any other element of device  12  that requires power. 
     Sensor system  22  can sense and detect changes in one or more environmental inputs. In the exemplary embodiment, the environmental inputs include wind or air flow directed toward device  12  as well as the orientation of device  12  with respect to the environment in which device  12  is located. Accordingly, in the exemplary embodiment sensor system  22  includes an air flow sensor subsystem  42  and an orientation sensor subsystem  44 . 
     In the exemplary embodiment, air flow sensor subsystem  42  includes the following sensors: an anemometer  46  and a microphone  48 . Nevertheless, in other embodiments such an air flow sensor subsystem can include additional or different types of air flow sensors. Also, note that although in the exemplary embodiment only a single sensor of each of the above-referenced types is described, other embodiments can include more than one sensor of each such type. Although only the sensors of air flow sensor subsystem  42  are individually shown in  FIG. 3 , it should be understood that air flow sensor subsystem  42  can include additional mechanical, electronic or other devices and structures that interface the air flow sensors with device controller  36  or otherwise aid or contribute to the operation of the air flow sensors. As persons of ordinary skill in the art are capable of providing the sensors described herein, mounting the air flow sensors in housing  18  or otherwise coupling the air flow sensors to housing  18  in a suitable manner, interfacing the air flow sensors with device controller  36 , and otherwise configuring device  12  to operate as described herein, such aspects of the exemplary embodiment are not described herein in further detail. Rather, the following can be noted about the air flow sensors of air flow sensor subsystem  42 . 
     Anemometer  46  is mounted in housing  18  or otherwise coupled to housing  18  in a manner that enables anemometer  46  to measure air flow through openings  28 ,  29 ,  30 ,  31  and the openings that oppose openings  28  and  29  ( FIGS. 2A-B ). Anemometer  46  can be, for example, a 3-vane anemometer that measures wind speed as a vector in three dimensions. That is, anemometer  46  measures the mutually orthogonal x, y and z components of the wind flow, where directions  32  and  34  ( FIG. 2A ) are oriented along the x and y axes of a 3-dimensional reference system, respectively, and direction  35  ( FIG. 2B ) is oriented along the z axis of the reference system. 
     Microphone  48  is mounted in housing  18  or otherwise coupled to housing  18  in a manner that enables microphone  48  to sense the sound resulting from air flow (i.e., wind) past or through housing  18 . 
     In the exemplary embodiment, orientation sensor subsystem  44  includes the following sensors: a compass or orientation magnetometer  50 , a gyroscope  52 , an accelerometer  54  and a camera  56 . Nevertheless, in other embodiments such an orientation sensor subsystem can include additional or different types of orientation sensors. Also, note that although in the exemplary embodiment only a single sensor of each of the above-referenced types is described, other embodiments can include more than one sensor of each such type. Although only the sensors of orientation subsystem  44  are individually shown in  FIG. 3 , it should be understood that orientation sensor subsystem  44  can include additional mechanical, electronic or other devices and structures that interface the orientation sensors with device controller  36  or otherwise aid or contribute to the operation of the orientation sensors. As persons of ordinary skill in the art are capable of providing the orientation sensors described herein, mounting the orientation sensors in housing  18  or otherwise coupling the sensors to housing  18  in a suitable manner, interfacing the orientation sensors with device controller  36 , and otherwise configuring device  12  to operate as described herein, such aspects of the exemplary embodiment are not described herein in further detail. Rather, the following can be noted about the orientation sensors of orientation sensor subsystem  44 . 
     Magnetometer  50  is mounted in housing  18  or otherwise coupled to housing  18  in a manner that enables magnetometer  50  to sense the geographic direction in which housing  18  is oriented, in the manner of a compass. However, magnetometer  50  can alternatively be used to measure wind energy and wind velocity. For example, to measure wind energy, magnetometer  50  can be a 3DOF magnetometer that hangs inside housing  18  and thus behaves like a pendulum with respect to the motion of tree branch  26 . The resting position of device  12  can be determined by computing the median value of readings from magnetometer  50  during periods of rest (as determined by low variation in the magnetometer readings). The subsystem oscillates when the wind blows. The upper point of the oscillation is detected as the point at which the magnetometer readings have the greatest difference from the resting position. This greatest difference can provide a measurement of wind energy at that instant. 
     Gyroscope  52  is mounted in housing  18  or otherwise coupled to housing  18  in a manner that enables gyroscope  52  to sense changes in orientation of housing  18 . Gyroscope  52  may be based upon microelectromechanical structures (MEMS) technology or other suitable technology. Gyroscope  52  may of a single-axis type, a two-axis type, or a three-axis type. 
     Accelerometer  54  is mounted in housing  18  or otherwise coupled to housing  18  in a manner that enables accelerometer  54  to sense the quantity that is commonly known as “proper acceleration” or “g-force.” A change in proper acceleration of housing  18  is indicative of a change in orientation of housing  18 . 
     Camera  56  is mounted in housing  18  or otherwise coupled to housing  18  in a manner that enables camera  56  to capture images of the environment so that changes in the images can be sensed. A change in the captured image is indicative of a change in orientation of housing  18 . 
     Piezoelectric sensor  58  is coupled to housing  18  in a manner that enables piezoelectric sensor  58  to sense the flexing of tree branch  26  ( FIGS. 2A-B ) or other support to which it is attached. Flexing of tree branch  26  is indicative of wind acting upon tree branch  26 . Piezoelectric sensor  58  can be, for example, a tape-like membrane that can be attached to the surface of tree branch  26 . 
     Light source  20  can include one or more individual sources of light, such as light-emitting diodes (LEDs), arranged in any suitable manner. In the exemplary embodiment, an external portion of light source  20  is located near the bottom of housing  18  ( FIGS. 2A-B ) so that the emitted light is most visible to observers who are located at or below the level of device  12 . The one or more LEDs (not individually shown) can be mounted within housing  18  in an orientation in which they emit the light through a transparent or translucent window portion of light source  20 . However, in other embodiments a light source can be integrated with a housing in any other suitable manner. 
     Light source  20  has a maximum useful range. That is, light source  20  can emit light that is visible to an average human observer from within a range of distances from light source  20  but not visible at substantially greater distances. In the system shown in  FIG. 1 , all of the multiplicity of devices  12  are located within this range of distances from at least one observation location (represented by observer  16 ). That is, observer  16  or others at such observation locations are generally able to see the light emitted by all of the multiplicity of devices that are distributed in the three-dimensional space, even though there may be additional devices  12  (not shown) that are not included in that multiplicity. Alternatively or in addition, in the system shown in  FIG. 1  the multiplicity of devices  12  are distributed within the three-dimensional space at locations from which all devices  12  of that multiplicity emit light that is perceived by observer  16  or others at such observation locations to have substantially the same brightnesses. In summary, the multiplicity of devices  12  are not distributed so far apart from one another that they are not perceived by an observer as being part of the same overall display. Moreoever, none of the multiplicity of devices  12  is located so far apart from one or more others that it is effectively not visible due to its low perceived brightness relative to the perceived brightnesses of other devices  12  of the multiplicity. 
     In the exemplary embodiment, wireless communication system  40  includes a wireless transmitter  60 , a wireless receiver  62 , and an antenna  64 . As described below, device controller  36  can cause information to be wirelessly communicated to and from (i.e, transmitted to and received from) other devices  12  or other transmitters and receivers. Although in the exemplary embodiment wireless communication system  40  is based upon radio frequency transmissions, in other embodiments such a wireless communication system can be based on any other suitable phenomena, such as infrared transmissions. 
     Device controller  36  can comprise any suitable logic, such as a microcontroller or microprocessor-based system. As persons of ordinary skill in the art are capable of providing and programming or configuring such logic to operate in the manner described herein, details of such aspects are not described herein. For example, persons of ordinary skill in the art are capable of programming or configuring such logic to operate in accordance with the flow diagrams of  FIGS. 4 and 5 . 
     As indicated by block  66  in  FIG. 4 , operation of device  12  and system  10  ( FIG. 1 ) can begin or continue with the reading of one or more sensors of sensor system  22  ( FIG. 3 ). As described above, sensor system  22  provides a sensed environmental input to device controller  36 . As indicated by block  68 , device controller  36  or other element or combination of elements of device  12  can process the sensed environmental input. In the exemplary embodiment, the processing can include sensing whether there has been a change since a previous reading in any of the various environmental inputs sensed by the sensor system, such as air flow as sensed by anemometer  46  or microphone  48 , or orientation as sensed by magnetometer  50 , gyroscope  52 , accelerometer  54 , camera  56  or piezoelectric sensor  58 . Such processing can include performing a logical “OR” of various indications representing potential change in the sensed environmental inputs, such that if it is determined that any of the various sensed environmental inputs has changed, a collective indication of change (i.e., a logic-“1” or affirmative indication) is produced. Other examples of suitable processing are described in further detail below. Still other examples will occur readily to persons of ordinary skill in the art in view of the teachings herein. 
     If, as indicated by block  70 , a change in sensed environmental input is detected, such as indicated by the above-described collective indication of change, then device controller  36  activates light source  20 , as indicated by block  72 . Upon activation, light source  20  emits light. In an instance in which light source  20  is already activated at the time the determination indicated by block  70  is made, light source  20  continues to emit light. As described below, in more specific examples of processing and activation (block  72 ) of light source  20 , light source  20  can be caused to emit light that is perceived as different from the light previously emitted, such as light of a different brightness (luminance) or color (wavelength). Thus, the phrase “to activate light source  20 ” or “activating light source  20 ” includes any action that affects the light emitted by light source  20 . The sensing, processing, and activation steps described above can be performed on a periodic basis, such as, for example, every few milliseconds. 
     As illustrated in  FIG. 5 , in a similar but more detailed example of a method of operation of device  12  and system  10  ( FIG. 1 ), changes in the environmental inputs sensed by different sensors are used to affect different aspects of the light emitted by light source  20 . Many other examples of operation of device  12  and system  10  will occur readily to persons of ordinary skill in the art in view of these teachings, such as embodiments in which the processing includes algorithms that use two or more of the sensed environmental inputs in combination with each other to determine how to change one or more aspects of the emitted light. 
     As indicated by block  74 , device controller  36  ( FIG. 3 ) can read wind speed using anemometer  46 , microphone  42 , or a combination of both. Similarly, as indicated by block  76 , device controller  36  can read wind direction using one or more of magnetometer  50 , gyroscope  52 , accelerometer  54 , camera  56  and piezoelectric sensor  58 . Note that some of the sensors described herein as used for reading wind direction can also be used to determine wind speed by comparing successive readings. That is, the rate at which device  12  changes orientation may be indicative of wind speed. 
     As indicated by block  78 , device  12  can wirelessly communicate information with other devices  12  or other transmitters and receivers. Referring briefly to  FIG. 6 , in the exemplary embodiment the multiplicity of devices  12  that are distributed within the three-dimensional space ( FIG. 1 ) can wirelessly communicate information with each other and with a central controller  79 . Central controller  79  can receive information, such as sensor readings, from one or more devices  12 , process the information, and transmit a result of the processing to the devices  12  from which the sensor readings were received or other devices  12 . In different embodiments, such processing in central controller  79  can range from all of the processing described with regard to  FIG. 5  and other such computational processing, to little more than relaying the information to other devices  12 . The following represent some examples of operation of central controller  79  in different embodiments. 
     In some embodiments, central controller  12  can provide a control signal to be transmitted to a corresponding device  12 . That is, central controller  79  can control devices  12  individually. In such embodiments, each device  12  wirelessly receives a corresponding control signal and activates its light source  20  in response to the received control signal. 
     In other embodiments, central controller  79  acts as a relay or conduit through which each device  12  wirelessly receives the environmental input or other measurement information sensed by the sensor system  22  of at least one other device  12 . In such embodiments, each device  12  provides a control signal (at least in part) in response to the received measurement information and uses that control signal to activate its light source  20 . 
     In still other embodiments, at least one device  12  of a first type produces a control signal in response to the measurement information that it senses. At least one other device  12  of a second type wirelessly receives the control signal from the first device  12  and uses that control signal to activate its light source  20 . For example, a system can comprise many devices  12  of the second type that include light sources and wireless receivers but that economically do not include sensor systems. 
     Returning to  FIG. 5 , as indicated by block  80 , device controller  36  ( FIG. 3 ) can use the sensed wind speed to update a moving average of wind speed. In accordance with the alternative embodiments described above with regard to  FIG. 6 , the computation relating to the moving average can be performed by device controller  36  (i.e., of the same device  12  that sensed the wind speed), by another one of the devices  12 , or by a combination thereof. 
     Similarly, as indicated by block  82 , device controller  36  can use the sensed wind direction to update a moving average of wind direction. In accordance with the alternative embodiments described above with regard to  FIG. 6 , the computation relating to the moving average can be performed by device controller  36  (i.e., of the same device  12  that sensed the wind direction), by another one of the devices  12 , or by a combination thereof. 
     A change in wind speed or wind direction can be determined by comparing the most recent measurement with the moving average. If, as indicated by block  84 , device controller  36  determines that most recently sensed wind direction exceeds the moving average wind direction by more than a threshold amount, then device controller  36  can adjust the color of the light emitted by light source  20 , as indicated by block  86 . For example, each color of a predetermined set of colors can be assigned to indicate a specific geographic or compass direction, such as North, South, Southeast, Southwest, etc. If device controller  36  determines that most recently sensed wind direction is above or below the moving average by more than a threshold amount, then device controller  36  can adjust the color of the light emitted by light source  20  to indicate the most currently sensed direction. 
     Magnetometer  50  and the direction of gravity can be used to correlate wind direction with geographic direction, so that regardless of whether devices  12  are oriented in various geographic or compass directions all devices  12  will respond to the same wind direction by emitting the same color light. The magnetic field of the environment can be assumed to have the same direction across all devices  12 , as a way to define a shared 3D coordinate frame S for the devices  12 . At each device  12 , the direction of the magnetic field, vector m, is computed when that device  12  is in its resting position and defines the x-axis of coordinate frame S. The cross-product of the vector m and the gravity vector g when the device is in its resting position defines the y-axis of S, and the cross-product of the x- and y-vectors determines the z-axis of S. An alternative choice is made in the particular case where vector m is parallel to vector g. All devices  12  now share a common alignment of their x-, y-, and z-axes (because the direction of the magnetic field and the direction of gravity are the same at all devices  12 ). All subsequent measurements of direction at a device  12  can be placed in the shared coordinate frame S. In the case where a device  12  has moved away from its resting position, magnetometer  50  defines the change in orientation relative to the resting position and hence relative to S. 
     The three vanes of anemometer  46  are orthogonal to one another and oriented at known orientations relative to magnetometer  50 . The wind speed can be measured as s 1 , s 2 , s 3  at each anemometer. The wind velocity is specified by the three vectors s 1   d   1 , s 2   d   2 , s 3   d   3 , where d 1 , d 2 , d 3  are the unit vectors for the axes of the three anemometers in the shared coordinate frame S. The three vectors can be combined to determine the 3D vector for the wind velocity in the shared coordinate frame S. In still another alternative embodiment (not shown), a simpler system of two orthogonal vane anemometers can be used to determine wind velocity just in the 2D plane of those anemometers e.g. just in the horizontal plane. 
     If, as indicated by block  88 , device controller  36  determines that the most recently sensed wind speed exceeds the moving average wind speed by more than a threshold amount, then device controller  36  can adjust the brightness of the light emitted by light source  20 , as indicated by block  90 . For example, each brightness level or step in a graduated set of brightness levels can indicate a corresponding wind speed. If device controller  36  determines that the most recently sensed wind speed exceeds the moving average by more than a threshold amount, then device controller  36  can correspondingly increase the brightness of the light emitted by light source  20 . If device controller  36  determines that most recently sensed wind speed is below the moving average by more than a threshold amount, then device controller  36  can correspondingly decrease the brightness of the light emitted by light source  20 . 
     As noted above, computations involving moving averages and adjustments of brightness and color are intended only as examples of processing of sensed environmental inputs and ways in which light sources can be activated. Other embodiments may process sensed environmental inputs in other ways that are in addition to or different from those described above. Various embodiments can include such processing and activation methods in any suitable combination with each other and with other features. For example, some embodiments may sense and process wind direction but not wind speed, while other embodiments may sense and process wind speed but not wind direction. 
     As a result of the system operation described above, an observer  16  ( FIG. 1 ) can perceive an overall effect that is indicative of a three-dimensional wind field through tree  14  or other three-dimensional space in which the multiplicity of devices  12  are distributed. Observer  16  may perceive some areas of tree  14  becoming brighter than others or change colors in response to a gust of wind. The effect may be used to provide entertainment or for other purposes. Furthermore, the sensed environmental information may be collected through central controller  79  or other means and analyzed to help animators and others model the behavior of real trees in response to wind. 
     Also, while one or more embodiments of the invention have been described as illustrative of or examples of the invention, it will be apparent to those of ordinary skill in the art that other embodiments are possible that are within the scope of the invention. Accordingly, the scope of the invention is not to be limited by such embodiments but rather is determined by the appended claims.