Abstract:
Methods and apparatus are disclosed to activate a traffic control system by enhancing a presence of a vehicle. An example traffic control activator includes a housing formed from an electrically insulating material. An example traffic control activator also includes an annular sensor interface formed from an electrically conducting material disposed within a cavity formed within the housing, the annular sensor interface to produce a first electromagnetic field when exposed to a second electromagnetic field of an inductive traffic sensor.

Description:
RELATED APPLICATIONS 
       [0001]    This patent claims the benefit of U.S. Provisional Patent Application Ser. No. 61/928,683, filed Jan. 17, 2014, which is herein incorporated by reference in its entirety. 
     
    
     FIELD OF THE DISCLOSURE 
       [0002]    This disclosure relates generally to the field of traffic signal activation, and, more particularly, to activating traffic control systems by enhancing a presence of a vehicle. 
       BACKGROUND 
       [0003]    A large number of traffic control systems use wire coils embedded in roadways to control traffic signals that manage left-turn lanes, through lanes, and side streets. These traffic control systems detect vehicles above the wire loop. The sensitivity of the traffic control system is set so that larger vehicles, such as a car (e.g., a sedan, a minivan, a sport utility vehicle (SUV), etc.), will trigger the traffic control system. However, as a result, some smaller vehicles (e.g., small cars, motorcycles, bicycles, mopeds, motorized scooters, etc.) do not trigger these traffic control systems. Recognizing this problem, many states legally allow trapped drivers to ignore red lights after a certain period of non-detection and dangerously drive through the intersection. Safety is compromised in situations where drivers must disobey traffic signals to proceed through the intersection. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]      FIG. 1  illustrates an example intersection with an example traffic control system and an example traffic signal activator mounted to an example vehicle. 
           [0005]      FIG. 2  illustrates an example primary alternating magnetic field radiating from an example inductive loop of the example traffic control system. 
           [0006]      FIG. 3  illustrates an example traffic signal activator mounted to an example vehicle. 
           [0007]      FIG. 4  illustrates a secondary alternating magnetic field radiating from an annular sensor interface of the traffic signal activator mutually coupled with the primary alternating magnetic field radiating from the inductive loop of the traffic control system. 
           [0008]      FIG. 5  illustrates an example oscillating signal driving the inductive loop of the traffic control system before and after the inductive loop is damped. 
           [0009]      FIG. 6  illustrates the example traffic signal activator mounted to an underside portion of the example vehicle. 
           [0010]      FIG. 7  illustrates the example traffic signal activator mounted to an example fork of the example vehicle. 
           [0011]      FIGS. 8A and 8B  illustrate an example of the example traffic signal activator being deployably mounted to the example vehicle. 
           [0012]      FIG. 9  illustrates an example of the example traffic signal activator mounted on a frame of the example vehicle. 
           [0013]      FIG. 10  illustrates an example hand deployable example traffic signal activator. 
           [0014]      FIG. 11  is a flow diagram that illustrates an example interaction between an example traffic control system and an example traffic signal activator. 
       
    
    
       [0015]    The figures are not to scale. Instead, to clarify multiple layers and regions, the thickness of the layers may be enlarged in the drawings. Wherever possible, the same reference numbers will be used throughout the drawing(s) and accompanying written description to refer to the same or like parts. As used in this patent, stating that any part (e.g., a layer, film, area, or plate) is in any way positioned on (e.g., positioned on, located on, disposed on, or formed on, etc.) another part, indicates that the referenced part is either in contact with the other part, or that the referenced part is above the other part with one or more intermediate part(s) located therebetween. Stating that any part is in contact with another part indicates that there is no intermediate part between the two parts. Additionally, times indicated on the figures are not to scale. Instead, to clarify interactions, times between events may be increased or decreased. 
       DETAILED DESCRIPTION 
       [0016]    Examples disclosed herein may be used to activate traffic control systems by passively simulating the presence of a larger vehicle. For example, traffic control systems may incorporate inductive loops embedded beneath a lane (e.g. a turn-dedicated lane, a straight through lane, etc.) in a roadway. The traffic control system controls traffic signals at an intersection. For example, during off-hours (e.g., night times, early morning, etc.), full time, and/or during rush hour, infrequently used roads (e.g., rural roads, left-turn lanes, etc.) and/or side-streets that intersect major roads may be controlled so that the cross-traffic is not stopped except when a vehicle is present in or near the inductive loop. 
         [0017]    To detect vehicles, the example traffic control system drives an oscillating signal onto the inductive loop to produce an alternating magnetic field. The traffic control system detects metallic objects with a sufficient conductance profile (e.g., large vehicles, etc.) that come within or near the inductive loop. The traffic control system detects changes in the oscillating signal. Upon detecting a vehicle, the traffic control system triggers a traffic signal that, in turn, signals (e.g. activates a green light while activating a red light for cross-traffic, etc.) the vehicle to proceed through the intersection. Some vehicles, however, fail to trigger traffic control systems with inductive loops. For example, smaller vehicles (e.g., mopeds, motorcycles, bicycles, small cars, motorized scooters, etc.) may not have a sufficient conductance profile to trigger the traffic control system. Additionally, vehicles that have composite bodies and/or vehicles with frames far above the roadway may also not trigger the traffic control system. 
         [0018]    In the examples disclosed and described herein, a traffic signal activator is mounted and/or deployed near the surface of the roadway within the inductive loop of the traffic control system. The alternating magnetic field of the inductive loop of traffic control system may induce eddy currents in an annular sensor interface of the traffic signal activator. As the eddy currents are induced, the traffic signal activator produces a magnetic field with an opposite polarity to the magnetic field of the inductive loop. The alternating magnetic field of the traffic signal activator may induce eddy currents into the inductive loop and may damp the alternating magnetic field of the inductive loop. The induced eddy currents in the inductive loop may reduce the inductance of the inductive loop, which may reduce the impedance of the inductive loop. As a result, the oscillating signal may change. The traffic control system may detect the change in the oscillating signal and may trigger the traffic signal. 
         [0019]      FIG. 1  illustrates an example traffic signal control system  100  with an example control cabinet  102  connected to an example inductive loop  104 . In the illustrated example, control cabinet  102  is connected to a traffic signal  106 . In some examples, the control cabinet  102  is connected to multiple traffic signals  106  (e.g., opposing traffic signals, cross-traffic traffic signals, etc.) and/or multiple inductive loops  104 . In the illustrated example, the inductive loop  104  is embedded below a road surface  108  between lane boundaries  110  (e.g. lane dividing lines, curbs, traffic barriers, etc.). In some examples, the inductive loop  104  is embedded one to two inches below the road surface  108  and/or is made of multiple windings of conductive wire. 
         [0020]    The example traffic control system  100  detects when an example vehicle  112  (e.g., a moped, a motorcycle, a bicycle, a truck, a motorized scooter, etc.) equipped with an example traffic signal activator  114  is located within the inductive loop  104 . In some examples, upon detecting the example vehicle  112 , the example traffic control system  100  controls the traffic signals  106  to signal the vehicle  112  to turn and/or cross an intersection. In some examples, when the example vehicle  112  is detected, the example traffic control system starts a countdown timer and causes the traffic signal  106  to signal the example vehicle  112  to turn and/or cross the intersection (e.g. provide a turn signal, a green light, etc.) when the countdown timer reaches zero. 
         [0021]    In the illustrated example, the example inductive loop  104  has an inductance value and an impedance value. The inductance value of the inductive loop  104  is related to the impedance value of the example inductive loop  104 . Raising and lowering the inductance value raises and lowers the impedance value of the inductive loop  104 . However, the relationship between the inductance value and the impedance value may not be linear. 
         [0022]    In the illustrated example of  FIG. 1 , the example control cabinet  102  has an example driving system  116  and an example detecting system  118 . The example driving system  116  has an oscillator (e.g., a Colpitts-type oscillator) that drives an oscillating signal into the inductive loop  104  at a frequency. In some examples, the frequency of the oscillating signal is between 20 kHz to 200 kHz. The frequency of the oscillating signal is inversely related to the impedance value of the inductive loop  104  (e.g., the higher the impedance value, the lower the frequency). As  FIG. 2  illustratively shows, in some examples, the oscillating signal causes a primary alternating magnetic field  120  to radiate from the inductive loop  104 . While the example primary alternating magnetic field  120  illustrated in  FIG. 2  shows the magnetic field in one direction, the primary alternating magnetic field  120  alternated directions at the frequency of the oscillating signal. 
         [0023]    The example detecting system  118  of  FIG. 1  measures the frequency of the oscillating signal. In the illustrated example, the example detecting system  118  measures the frequency of the oscillating signal when a vehicle (e.g., vehicle  112 ) is not within the inductive loop  104  to establish a baseline frequency measurement. In some examples, the example detecting system  118 , from time to time, measures the frequency of the oscillating signal when a vehicle (e.g., the vehicle  112  of  FIG. 1 ) is not within the inductive loop  104  to update the baseline frequency measurement to compensate for changes in environmental factors, such as, a change temperature, rain, snow, etc. In the illustrated example, the detecting system  118  detects a vehicle (e.g., the vehicle  112  of  FIG. 1 ) when the frequency of the oscillating signal deviates beyond a tolerance from the baseline frequency measurement. 
         [0024]      FIG. 3  illustrates the example traffic signal activator  114  of  FIG. 1 . In the illustrated example, the example traffic signal activator  114  has an example annular sensor interface  122  and an example housing  124 . In the illustrated example, the annular sensor interface  122  is elliptical. However, the annular sensor interface  122  may be any shape. In some examples, the annular sensor interface  122  is a convex shape (e.g., circular, rectangular, hexagonal, etc.). In the illustrated example, the annular sensor interface  122  has a length and a width proportioned to allow the annular sensor interface  122  to be mounted on a vehicle (e.g., the example vehicle  112  of  FIG. 1 ) and/or to maximize the size of the annular sensor interface  122 . As disclosed in more detail below in connection with  FIG. 7 , in some examples, the annular sensor interface  122  is sized to fit around a wheel of the vehicle  112 . In some examples, the annular sensor interface  122  is  16  inches by  10  inches. The annular sensor interface  122  of the illustrated example is be made of an electrically conductive material (e.g., silver, copper, aluminum, zinc, nickel, iron, carbon (graphene)). In some examples, the electrically conductive material of the example annular sensor interface  122  is at least partially a diamagnetic material (e.g., copper, silver, gold, etc.). 
         [0025]    In some examples, at least a portion of the housing  124  is made of an electrically insulating martial (e.g., rubber, Teflon, plastic (e.g., polyethylene), ceramic, etc.) to electrically isolate the annular sensor interface  122  from any electrically conductive portion of the vehicle  112 . In the illustrated example, the housing  124  also protects the annular sensor interface  122  from external conditions, such as rain, rocks, snow, etc. In some examples, the annular sensor interface  122  is encased in the housing  124 . In other examples, the annular sensor interface  122  is attached to the housing  124  via non-conductive fasteners (e.g., screws, bolts, etc.). 
         [0026]    In the illustrated example of  FIG. 4 , when the example traffic signal activator  114  ( FIG. 1 ) enters the inductive loop  104  ( FIG. 1 ) of the traffic signal control system  100  of  FIG. 1 , the primary alternating magnetic field  120  induces eddy currents in the annular sensor interface  122 . The eddy currents in the annular sensor interface  122  produce an opposing secondary alternating magnetic field  126  with a polarity opposite the primary alternating magnetic field  120 . In the illustrated example, the secondary alternating magnetic field  126  suppresses the primary alternating magnetic field  120  emanating from the inductive loop  104  through mutual inductance. The mutual inductance between the inductive loop  104  and the annular sensor interface  122  is given by Equation 1 below. 
         [0000]    
       
         
           
             
               
                 
                   
                     M 
                     = 
                     
                       Φ 
                       I 
                     
                   
                   , 
                   . 
                 
               
               
                 
                   ( 
                   
                     Equation 
                      
                     
                         
                     
                      
                     1 
                   
                   ) 
                 
               
             
           
         
       
     
         [0000]    In Equation 1 above, M is the mutual inductance between the inductive loop  104  and the annular sensor interface  122 , Φ is a magnetic flux of the annular sensor interface  122 , and I is a current flowing through the inductive loop  104  from the oscillating signal. The higher the mutual inductance, the greater effect the traffic signal activator  114  has on the frequency of the oscillating signal. 
         [0027]    In the illustrated example, the eddy current induced in the inductive loop  104  by the secondary alternating magnetic field  126  reduces the inductance value of the inductive loop  104  and, as a result, reduces the impedance value of the inductive loop  104 . Reducing the impedance of the example inductive loop  104  increases the frequency of the example oscillating signal produced by the example oscillator of the driving system  116 . In the illustrated example of  FIG. 5 , the example oscillator of the example driving system  116  of  FIG. 1  initially drives the oscillating signal at a frequency F 1 . When the impedance value of the inductive loops  104  is reduced, the example oscillator drives the oscillating signal at a frequency F 2 . In the illustrated example, the frequency F 2  is greater than the frequency F 1 . The example detecting system  118  of  FIG. 1  detects the change in frequency from frequency F 1  to frequency F 2 . When the oscillating signal frequency crosses a detection threshold frequency, the example detecting system  118  detects the change in the frequency, and the example traffic control system  100  of  FIG. 1  changes the example traffic signal  106  ( FIG. 1 ) to indicate that a vehicle (e.g., the vehicle  112  of  FIG. 1 ) may turn/proceed through the intersection. 
         [0028]    In the examples illustrated in  FIGS. 6-8 , the traffic signal activator  114  is mounted to the vehicle  112 . In the illustrated examples, the traffic signal activator  114  is suspended (e.g., by the housing  124 ) a distance above the roadway surface  108  ( FIG. 1 ). In some examples, the distance is between six inches and ten inches. The example traffic signal activator  114  is electrically isolated from the vehicle  112 . 
         [0029]    In the illustrated example of  FIG. 6 , the example traffic signal activator  114  is mounted to an underside portion  128  of the vehicle  112 . In some examples, the traffic signal activator  114  is mounted to the vehicle  112  via an aperture  127  defined by the housing  124  and a fastener (e.g., a screw, a bolt, etc.). In some such examples, the underside portion  128  of the vehicle  112  has a threaded opening  129  to accept the fastener. In the illustrated example, the housing  124  of the traffic signal activator  114  is mounted so that the annular sensor interface  122  is parallel to the road surface  108  (e.g., the annular sensor interface  122  is normal to the primary alternating magnetic field of  FIGS. 2 and 4  when the traffic control system  122  is within the inductive loop  104 ). In some examples, the example annular sensor interface  122  deviates from being parallel with the road surface  108 . In the illustrated example, the annular sensor interface  122  is disposed within a cavity formed by the housing  124 . In some such examples, the annular sensor interface  122  is between an interior portion of the housing  124  defining the cavity and the exterior portion of the housing  124 . Additionally, in the illustrated example, the example housing  124  electrically isolates the example annular sensor interface  122  from the underside portion  128  of the example vehicle  112 . 
         [0030]    In the illustrated example of  FIG. 7 , the example traffic signal activator  114  is coupled to a fork  130  of the vehicle  112  via a fork cap  131 . The traffic signal activator  114  of the illustrated example extends around an example wheel  132  of the example vehicle  112 . In the illustrated example of  FIG. 7 , the traffic signal activator  114  extends around the example wheel  132  that is at the front of the example vehicle  112 . In some examples, the example traffic signal activator  114  extends round a back wheel of the example vehicle  112 . 
         [0031]    The example housing  124  and the fork cap  131  electrically isolate the example annular sensor interface  122  from the example fork  130  of the example vehicle  112 . In the illustrated example, the housing  124  substantially conforms to the shape of the annular sensor interface  122 . In some examples, the housing  124  and the annular sensor interface  122  pass through apertures defined by the fork cap  131 . Fasteners  133  engage the housing  124  and the fork cap  131  to secure the substantially parallel to the road surface  108  (e.g., the annular sensor interface  122  is normal to the primary alternating magnetic field of  FIGS. 2 and 4  when the traffic control system  122  is within the inductive loop  104 ). In some examples, the example annular sensor interface  122  deviates from being parallel with the road surface  108 . In some example, the fasteners  133  are non-conductive. In the illustrated example, the fork caps  131  are configured to slide onto the bottom of the fork  130  without interfering with the front shocks of the vehicle  112 . The example fork caps  131  are attached to the fork  130  via fasteners  135 . In some examples, the fasteners  135  also couple the fork  130  to the wheel hub  137  of the wheels  132  of the vehicle  112 . 
         [0032]    In the illustrated example of  FIGS. 8A and 8B , the example traffic signal activator  114  is mounted to the example vehicle  112  via a hinge connection  134 . In some examples, the traffic signal activator  114  is fixed to the fork  130  of the vehicle  112  via a mount 139  and one or more mounting brackets  141 . In the illustrated example of  FIG. 8A , the example traffic signal activator  114  is locked into a vertical position substantially perpendicular to the surface of the roadway (e.g., the roadway  108  of  FIG. 1 ) while, for example, the vehicle  112  is being driven by a driver. The driver of the example vehicle  112  deploys the example traffic signal activator  114  from the vertical position illustrated in  FIG. 8A  to a horizontal position illustrated in  FIG. 8B  when the example vehicle is within the inductive loop  104  of the traffic signal control system  100 . In some examples, the active signal activator  114  is connected to a base  136  via a fastener  143  that engages the housing  124  though a hollow portion of the housing  124 . In some examples, a cap  145  fixes the housing  124  relative to the fastener  143  so the housing  124  does not rotate around an axis of the fastener  143 . The example based is connected to the mount  139  via the hinge connection  134 . In such examples, the position of the base  136 is controlled by pedal(s) and/or lever(s) (not shown) through a transfer mechanism  138  (e.g., a Bowden cable, rod(s), hydraulics, etc.). In the illustrated example of  FIG. 8B , when the traffic signal activator  114  is in the horizontal position, the annular sensor interface  122  is substantially parallel to the road surface  108  (e.g., the annular sensor interface  122  is normal to the primary alternating magnetic field of  FIGS. 2 and 4  when the traffic control system  122  is within the inductive loop  104 ). In some examples, upon the activation of the traffic control system  100 , the traffic signal activator  114  is returned to the vertical position. 
         [0033]    In the illustrated example of  FIG. 9 , the traffic signal activator  114  is attached to a frame  140  of the vehicle  112  (e.g., a bicycle, etc.) via one or more straps  142 . In the illustrated example, the straps  142  wrap around the frame  140  and one or more loops  144  protruding from the housing  124  of the active signal activator  114 . In some examples, the straps  142  may be fastened with a fastening device  146  (e.g., a slide release buckle, a ladder lock buckle, Velcro™, etc.). In the illustrated example, when the straps  142  are engaged with the housing  124  and the body of the vehicle  112 , the housing is situated in a plane formed by a top tube  151 , a seat tube  152 , and a down tube  154  of the vehicle  112 . In the illustrate example, the driver of the vehicle  112  deploys the traffic signal activator  114  by pivoting the vehicle  112  so that the traffic signal activator  114  is substantially parallel (e.g., the annular sensor interface  122  is normal to the primary alternating magnetic field of  FIGS. 2 and 4 ) with the road surface  108  ( FIG. 1 ) within the inductive loop  104  ( FIG. 1 ) of the traffic control system  110  ( FIG. 1 ) 
         [0034]    In the illustrated example of  FIG. 10 , the traffic signal activator  112  is attached to a tether  148 . The tether  148  of the illustrated example has a hand loop  150 . The example tether  148  engages a ring  156  (e.g., a D-ring, etc.) via a ring loop  158  formed by the tether  148 . In some examples, the ring  158  is coupled to the housing  124  via a plate  160  fixed to the housing  124 . In some examples, the driver of the vehicle  112  deploys the example traffic signal activator  114  by placing the example traffic signal activator  114  of  FIG. 9  on the road surface  118  when within the inductive loop  104  of the traffic signal control system  100 . Upon the activation of the example traffic control system  100 , the driver uses the example tether  148  to retrieve the example traffic signal activator  114 . 
         [0035]      FIG. 11  depicts a flow datagram illustrating an example interaction between the example traffic control system  100  of  FIG. 1  and the example traffic signal activator  114  of  FIGS. 1 and 3 . Initially, at time T 0 , the driving system  116  ( FIG. 1 ) of the control cabinet  102  ( FIG. 1 ) drives an oscillating signal onto the induction loop  104  at a frequency F 1 . At a time T 1 , the detection system  118  ( FIG. 1 ) of the example control cabinet  102  measures the frequency of the oscillating signal to establish a baseline frequency. As shown at an example time T 2 , from time to time, the detection system  118  measures the frequency of the oscillating signal. In the illustrated example, at T 2 , the frequency of the oscillating signal is frequency F 1 . At a time T 3 , the example traffic signal activator  114  enters the example inductive loop  104  ( FIG. 1 ). The example primary alternating magnetic field  120  ( FIG. 2 ) induces eddy currents in the example annular sensor interface  122  ( FIG. 3 ) of the example traffic signal activator  114 . At a time T 4 , the example secondary alternating magnetic field  126  ( FIG. 4 ) suppresses the primary alternating magnetic field  120 . As a result, the oscillating signal begins to oscillate at a frequency F 2 . At a time T 5 , the detection system  118  measures the frequency of the oscillating signal and detects that the frequency has changed. At a time T 6 , the control cabinet  102  changes the traffic signal  106  to indicate that a vehicle (e.g., the vehicle  112  of  FIG. 1 ) may turn/proceed through the intersection. Finally, at a time T 7 , after the traffic signal activator  114  leaves the inductive loop  104 , the frequency of the oscillating signal is the frequency F 1  and the detection system  118  monitors oscillating signal to detect another vehicle. 
         [0036]    For example, when a motorcycle (e.g., a vehicle  112 ) equipped with a traffic signal activator  114  enters perimeter of the inductive loop  104  at a traffic signal  106  that is red, the primary alternating magnetic field  120  of the inductive loop  104  induces a current in the annular sensor interface  122  of the traffic signal activator  114 . As a result, an opposing secondary alternating magnetic field  126  is generated by the annular sensor interface  114 , which suppresses the primary alternating magnetic field  120 . The suppression of the primary alternating magnetic field  120  increases the frequency of the oscillating signal of the inductive loop  104 . When the detection system  118  detects the change in frequency of the oscillating signal, the control cabinet  102  signals for the traffic control signal  106  to change to green. In such an example, the motorcycle may proceed through the intersection causing the traffic signal activator  114  to exit the inductive loop  104 . The frequency of the oscillating signal of the inductive loop  104  returns to its baseline frequency. 
         [0037]    From the foregoing, it will be appreciated that the above disclosed methods and apparatus do not require extra electronics to be installed on a vehicle. Additionally, the above disclosed methods and apparatus provide for multiple configurations to be mounted on the vehicle. 
         [0038]    Although certain example methods, apparatus and articles of manufacture have been disclosed herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus and articles of manufacture fairly falling within the scope of the claims of this patent.