Note: Descriptions are shown in the official language in which they were submitted.
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ACCESSIBLE PEDESTRIAN SIGNAL SYSTEM
Technical Field
[0001] This invention relates to systems and methods for accessible pedestrian
signal
(APS) systems which provide non-visual pedestrian signal indications.
Back rgound
[0002] APS systems provide pedestrian signal indications in a non-visual
format such as:
audible (e.g. sounds, tones, verbal messages, etc.) or vibrotactile (e.g.
vibrating raised
pushbutton surface) formats. APS systems may generate different types of
signal
indications for different applications. For example, APS systems typically
have different
audible "walk" indications for east-west and north-south crossings, in
addition to pole
locator tones, wait tones, and the like. It is important that APS systems
provide correct
pedestrian signal indications to protect the safety of visually impaired or
visually and
hearing impaired pedestrians.
[0003] A traffic light control system typically incorporates a malfunction
management
unit (MMU) which monitors traffic signal channels for conflicting inputs and
invalid
signal voltage levels and the like, and responds to a detected failure or
abnormal
condition. As conventional MMUs are designed for traffic control systems which
provide
basic visual traffic signal information, such MMUs may generally lack the
control to
reliably recognize and respond to conflict or error in non-visual pedestrian
signal
indications as generated by APS systems, and particularly, with respect to
multiple types
of audible indications for different applications.
[0004] There is a general desire to provide conflict monitoring and error
detection for
APS systems. There is a general desire to provide APS systems incorporating
conflict
monitoring and error detection which may be retrofit into existing traffic
control systems.
Brief Description of Drawings
[0005] Exemplary embodiments are illustrated in referenced figures of the
drawings. It is
intended that the embodiments and figures disclosed herein are to be
considered
illustrative rather than restrictive.
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[0006] Figure 1 schematically depicts a conflict monitoring and error
detection system
according to a particular embodiment which may be implemented for an APS
button
station.
[0007] Figure 2 schematically depicts a primary conflict monitor and error
detector
according to one embodiment that may be used in the conflict monitoring and
error
detection system of Figure 1.
[0008] Figure 3 depicts the contents of a sound file that may be used in the
conflict
monitoring and error detection system of Figure 1.
[0009] Figure 4 schematically depicts a specific implementation of the Figure
2 primary
conflict monitor and error detector according to one embodiment.
[0010] Figure 5 schematically depicts a specific implementation of a secondary
conflict
monitor and error detector according to one embodiment that may be used in the
conflict
monitoring and error detection system of Figure 1.
[0011] Figure 6 is a flowchart illustrating a method of conflict monitoring
and error
detection according to one embodiment that may be performed by the primary
conflict
monitor and error detector of Figure 2.
[0012] Figure 7 is a flowchart illustrating another method of conflict
monitoring and error
detection according to one embodiment that may be performed by the primary
conflict
monitor and error detector of Figure 2.
[0013] Figure 8 is a flowchart illustrating a method of conflict monitoring
and error
detection according to one embodiment that may be performed by the secondary
conflict
monitor and error detector of Figure 5.
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Description
[0014] Throughout the following description, specific details are set forth in
order to
provide a more thorough understanding to persons skilled in the art. However,
well
known elements may not have been shown or described in detail to avoid
unnecessarily
obscuring the disclosure. Accordingly, the description and drawings are to be
regarded in
an illustrative, rather than a restrictive, sense. As used herein, "actual"
signals,
indications, parameters, modes and the like refer to signals, indications,
parameters,
modes and the like actually generated, provided and/or output by an APS
system,
regardless of whether the APS system is functioning correctly. "Expected"
signals,
indications, parameters, modes and the like refer to signals, indications,
parameters,
modes and the like which are expected to be, or ought to be, generated,
provided and/or
output by an APS system which is functioning correctly.
[0015] According to particular embodiments, an APS system is integrated into a
pedestrian button station provided at a pedestrian crosswalk. Each button
station has a
pushbutton which may be pushed by the pedestrian to request service from a
traffic signal
controller at the crosswalk (i.e. to request the go-ahead signal to cross the
street). The
pushbutton may be a vibrotactile raised pushbutton capable of providing
vibrotactile
pedestrian signal indications. The button station may include a "button"
speaker (so-
named as it is located at the button station). The APS system may optionally
include an
overhead speaker, typically mounted in or to a pedestrian signal head which
provides
visual pedestrian signal indications. The button and overhead speakers may
play audible
pedestrian signal indications such as sounds, tones, verbal messages and the
like.
[0016] The button station incorporates a primary conflict monitor and error
detector
which controls the outputs to the button speaker (and the overhead speaker, if
provided)
and the vibration actuator for the pushbutton. In particular embodiments, the
speakers and
vibration actuator may be in a disabled state by default, and may be enabled
only when
the primary conflict monitor and error detector has verified that conditions
are such that
the speakers and vibration actuator may be enabled. For example, one condition
that may
be verified is whether the actual signals sent to the speakers or vibration
actuator match
the expected signals for the speakers or vibration actuator based on the
current traffic
state as determined from pedestrian signals (e.g. WALK, FLASHING DON'T WALK,
or
SOLID DON'T WALK) and user settings (which for an audio signal may define
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parameters such as the sound type for a particular traffic state, frequency of
sound output,
etc., and for a vibrotactile signal may define parameters such as the mode of
vibratory
feedback for a particular traffic state).
[0017] According to particular embodiments, sound files representing audible
pedestrian
signal indications are encoded with a digital code representing information
about (i.e.
meta data) or identifying parameters of the signal indication such as:
pedestrian signal
type, sound type, message, and length of the message. The primary conflict
monitor and
error detector detects and receives signals to be sent to the speakers,
decodes the portions
of the signals containing the digital code of a sound file, and based on such
decoded
information, verifies that the sounds to be played by the speakers conform
with the
current traffic state and user settings. In certain embodiments, the primary
conflict
monitor and error detector also detects and receives signals to be sent to the
vibration
actuator, and verifies that the signals conform with the current traffic state
and user
settings.
[0018] In some embodiments, secondary conflict monitoring and error detection
may be
implemented by an APS malfunction management subsystem. The button station may
transmit information about its actual non-visual pedestrian signal indications
to the APS
malfunction management subsystem, which verifies such information against the
current
traffic state and user settings (to determine whether the actual signals match
the expected
signals), detects conflict or error, and responds to any detected conflict or
error. Such
response may include inhibiting audible and/or vibrotactile output at the
button station
where the conflict or error is detected. In particular embodiments,
information about a
button station's actual non-visual pedestrian signal indications is sent to
the APS
malfunction management subsystem over a powerline communications network.
[0019] Figure 1 illustrates a conflict monitoring and error detection system
100 according
to a particular embodiment for an APS button station 80 which includes a
pushbutton 82
and a button speaker 84. An optional overhead speaker 86 is mounted in a
pedestrian
signal head 88. Speakers 84, 86 are operable to play audible pedestrian signal
indications
(e.g. sounds, tones, verbal messages and the like). Pushbutton 82 may comprise
a
vibrotactile raised pushbutton which may be driven by an actuator 109 to
provide
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vibrotactile pedestrian signal indications (e.g. vibrations which may be
detected by a
pedestrian touching pushbutton 82).
[00201 Pedestrians wishing to cross the street may request service from
traffic signal
controller 90 by pushing pushbutton 82. Pedestrian input to pushbutton 82 is
provided by
wire 83 to traffic signal controller 90. Traffic signal controller 90
generates traffic control
signals including pedestrian signals, and communicates the pedestrian signals
to
pedestrian signal head 88.The pedestrian signals are carried over two wires or
lines:
line 92A which may assert the WALK signals and line 92B which may assert the
DON'T
WALK (and flashing DON'T WALK) signals. Signals asserted on lines 92A, 92B
determine the current traffic state for pedestrians at button station 80 (i.e.
WALK,
FLASHING DON'T WALK, or SOLID DON'T WALK).
[00211 Button station 80 receives pedestrian signals through a power interface
module 78
connected between pedestrian signal head 88 and button station 80 (see Figure
1). Power
interface module 78 may incorporate a rectifier circuit (not shown) to convert
the AC
voltage of lines 92A, 92B to a DC voltage at a voltage level suitable for use
in button
station 80 (for example, from 120V AC at lines 92A, 92B to 12V DC at lines
92A', 92B').
In the illustrated embodiment, pedestrian signals provided to button station
80 are carried
over a 12V DC line 92A' providing the WALK signals and a 12V DC line 92B'
providing
the DON'T WALK (and flashing DON'T WALK) signals.
[00221 As shown in Figure 1, an earth ground line 94 and an AC neutral line 96
are
connected to traffic signal controller 90 and to pedestrian signal head 88.
Earth ground
line 94 may be connected to DC common lines, in some embodiments. Information
from
button station 80 may be transmitted via a combination of lines 85 and 94 at
the DC side
of the power interface module 78 and lines 92A, 92B and/or 96 (collectively, a
"powerline
communications line 95") at the AC side of the power interface module 78. Line
85 may
be a communications wire between button station 80 and power interface module
78.
Information from button station 80 may be communicated over the powerline
communications line 95 to other button stations connected to traffic signal
controller 90.
Information from button station 80 may be transmitted over powerline
communications
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line 95 to a secondary conflict monitor and error detector 103 through
communications
interface unit 120.
[00231 An APS generator 98 in button station 80 generates control signals for
providing
non-visual (e.g. audible and vibrotactile) pedestrian signal indications,
based on the
pedestrian signals carried over lines 92A', 92B' to button station 80. APS
generator 98
transmits the control signals to the appropriate outputs (e.g. speakers 84, 86
and vibration
actuator 109). Before such control signals reach their intended outputs, they
are processed
and verified by a primary conflict monitor and error detector 102 of system
100. Primary
conflict monitor and error detector 102 may be contained within button station
80's
housing.
[00241 As shown in Figure 2, primary conflict monitor and error detector 102
controls the
state of a relay or switch 106 connected between APS generator 98 and speakers
84, 86.
Relay 106 may be positioned prior to audio amplifier 108 in the path between
APS
generator 98 and speakers 84, 86. Primary conflict monitor and error detector
102
controls the state of a relay or switch 107 connected to vibration actuator
109. In particular
embodiments, relays 106 and 107 are by default in their open (disabled) state.
It is only
after primary conflict monitor and error detector 102 determines that certain
conditions are
satisfied (or that no conflicts or errors are detected) that relays 106 and
107 are switched
temporarily to their closed (enabled) states thereby enabling audible output
from speakers
84, 86 and vibrotactile output from pushbutton 82.
[00251 In the illustrated embodiment, APS generator 98 controls the state of a
relay or
switch 106A connected to speaker 84 and a relay or switch 106B connected to
speaker 86.
APS generator 98 may control the state of relays 106A, 106B based at least in
part on
configurable user settings 91 for button station 80 stored in a memory 111 at
button
station 80. User settings 91 are explained in further detail below.
[00261 According to certain embodiments, audio control signals sent to
speakers 84, 86
are encoded with digital codes or signatures which, when decoded by primary
conflict
monitor and error detector 102, identify parameters of the audible pedestrian
signal
indications that are to be played by speakers 84, 86. Each sound available for
output by
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speakers 84, 86 may be stored in audio format as a sound file 89 including a
header 87
containing a digital code (see Figure 3). The audio control signals that are
generated by
APS generator 98 include the digital code for each sound file 89. The digital
code
provides information about the sound in each sound file 89, such as:
= Signal type (e.g. WALK, FLASHING DON'T WALK, SOLID DON'T WALK and/or
other signal types).
= Sound code or number identifying the type of sound (e.g. chirp; cuckoo;
click; beep; a
particular tune; a verbal message such as "walk sign is on", "wait",
"emergency
vehicle approaching," or "train approaching"; etc.).
= Sound description (text field identifying the sound type in a written
description - e.g.
"chirp", "cuckoo").
= Length of the message (e.g. this may typically range from approximately 0.1
second to
approximately 3 seconds).
= Message (e.g. walk - east-west crossing; walk - north-south crossing; wait
or clear the
crosswalk; don't walk; pole locator; button press acknowledged; pedestrian
call
acknowledged; train crossing; error alert, etc.).
In certain embodiments, a portion of each header 87 may be represented as a
sound
reference number (see Figure 3). The sound reference number may identify
information
for certain fields such as signal type, sound type and/or message. The sound
reference
number may be used as an index to a look-up table that identifies signal type,
sound type,
and/or message.
[00271 A plurality of sound files 89, each sound file 89 representing a sound
available for
output to speakers 84, 86, may be stored in memory 111 at button station 80
(Figure 2). In
the Figure 2 embodiment, memory 111 also stores configurable user settings 91
for button
station 80. User settings 91 may define settings for button station 80 such as
the sound
type for a message and signal type; the order in which messages are to be
played; the
frequency at which a message is to be repeated; the maximum duration over
which a
particular message is to be repeated; the speakers from which the sounds are
to be played
(e.g. button speaker, overhead speaker, or both); the volume of sounds,
including
maximum and minimum volume levels, gain above ambient volume levels, time-
specific
maximum volume levels (e.g. maximum volume levels applied during evenings or
at
night); order in which messages are to be played; and the like. Different user
settings 91
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may apply depending on the operating conditions, such as whether the
pedestrian's button
push is long or short in duration.
[0028] Memory 111 may be accessible to processor 99 of APS generator 98 and
processor 110 of primary conflict monitor and error detector 102. Processor 99
receives
pedestrian signals asserted on lines 92A', 92B', and executes instructions
provided by
software stored in program memory 93 to retrieve user settings 91 from memory
111,
select one or more sound files 89 from memory 111 (based on the input
pedestrian signals
and user settings 91), and generate audio signals 105 (control signals which
are sent to
audio amplifier 108). Audio signals 105 may be pulse-width modulated signals,
in
particular embodiments. In other embodiments, processor 99 generates digital
audio
signals. Digital audio signals may be converted to analog pulse-width
modulated signals
by a signal converter for playback by speakers 84, 86. In some embodiments,
processor 99
may synthesize digital audio signals based on data (e.g. textual data) stored
in memory
111.
[0029] In certain embodiments, processor 99 sends signals to selectively open
or close
relays 106A, 106B based on relevant user settings 91. Relevant user settings
91 may
identify, for example, one or more of. the speaker(s) from which each message
is to be
played (e.g. button speaker, overhead speaker, or both), the frequency at
which an audible
message is to be repeated; the duration of the audible message, and/or the
like.
[0030] Audio amplifier 108 amplifies audio signals 105 to provide suitable
audio
signals 97 to drive speakers 84, 86 to play audible pedestrian signal
indications. Primary
conflict monitor and error detector 102 detects and receives the audio signals
prior to their
output to speakers 84, 86. In particular embodiments, conflict monitor and
error
detector 102 detects and receives audio signals 97 prior to their
amplification by audio
amplifier 108 and before their output to speakers 84, 86.
[0031] Primary conflict monitor and error detector 102 decodes each detected
signal 97.
In particular embodiments (such as those described with reference to Figure
3), each
sound file 89 may contain a digital code in a header 87, represented by the
first n bits of
each sound file 89. Primary conflict monitor and error detector 102 may decode
the
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beginning portion of each detected signal 97 corresponding to header 87 of a
sound file
89. Primary conflict monitor and error detector 102 compares the decoded
information
with the current traffic state and user settings 91 (as accessed from memory
111). Primary
conflict monitor and error detector 102 may determine the current traffic
state (e.g.
WALK, FLASHING DON'T WALK, or SOLID DON'T WALK) by monitoring
pedestrian signals carried over lines 92A', 92B'.
[00321 If certain conditions are satisfied (as described in further detail
below), primary
conflict monitor and error detector 102 moves relay 106 to a closed position,
enabling
signal 97 to be played by one or both of speakers 84, 86 (depending on the
state of relays
106A, 106B which are controlled by APS generator 98). According to particular
embodiments described herein, the portion of signal 97 that is output to and
played by
speakers 84, 86 includes the audible pedestrian signal indication, but
excludes sound
header information. Header 87 of sound file 89 is not output to speakers 84,
86 because
relay 106 is maintained in its default open position while primary conflict
monitor and
error detector 102 is processing and decoding header 87. Therefore, the
portion of signal
97 that represents header 87 of sound file 89 is prevented from reaching
speakers 84, 86.
[00331 In particular embodiments, for each signal 97 detected by primary
conflict monitor
and error detector 102, primary conflict monitor and error detector 102 may
evaluate
whether the following conditions are satisfied:
= A valid header 87 is decoded from signal 97. A missing, invalid or
unrecognizable
header is indicative of a conflict or error.
= A valid traffic state (i.e. WALK, FLASHING DON'T WALK, or SOLID DON'T
WALK) is determinable from signals on lines 92A', 92B'. Signals should be
asserted
on only one of lines 92A', 92B' at any one time. A simultaneous assertion of
signals
(or no assertion of signals) on lines 92A', 92B' is indicative of a conflict
or error. For
example, a short circuit (such as may be caused by water leaking into button
station
80's housing) may result in simultaneous assertion of signals on lines 92A',
92B'.
= The signal type of signal 97 (as determined by the signal type decoded from
header 87)
matches the current traffic state (e.g. as determined by the signals on lines
92A',
92B'). A mismatch in the signal type is indicative of a conflict or error.
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The The sound type of signal 97 (as determined by the sound type decoded from
header 87)
matches the sound type set in user settings 91 for the current traffic state.
For example,
for a current traffic state of WALK, user settings 91 may specify that the
sound type is
a cuckoo sound. A mismatch in the sound type is indicative of a conflict or
error.
[0034] In other embodiments, other conditions may be evaluated by primary
conflict
monitor and error detector 102 to determine whether the actual signals match
the expected
signals for speakers 84, 86 and vibration actuator 109. For example, audio
signals 97 may
be evaluated to determine if the sounds to be played conform with other
parameters
defined in user settings 91 (e.g. the order in which messages are to be
played, the
frequency at which a message is to be repeated, the maximum duration over
which a
particular message is to be repeated, etc.).
[0035] If the foregoing conditions are satisfied (i.e. no conflict or error is
detected),
primary conflict monitor and error detector 102 closes relay 106 for a
duration based on
the message length, as specified in header 87. Once relay 106 has closed for
the
determined duration, it returns to its default open position.
[0036] If one of the foregoing conditions is not satisfied (i.e. a conflict or
error is
detected), relay 106 is maintained in its default open position. Primary
conflict monitor
and error detector 102 may transmit an error message, providing information
about the
detected conflict or error, via powerline communications line 95 to an APS
malfunction
management subsystem 104 (described in further detail below). Audible output
may
remain disabled until button station 80's operation is reset by service
personnel.
[0037] In addition to verifying audio signals to speakers 84, 86, vibrotactile
control
signals generated by APS generator 98 may be verified by primary conflict
monitor and
error detector 102 prior to being received at vibration actuator 109. In the
illustrated
embodiment of Figure 2, primary conflict monitor and error detector 102
detects and
receives control signals 112 for driving vibration actuator 109. Control
signals 112 are
generated by APS generator 98 based on user settings 91 and the pedestrian
signals carried
over lines 92A', 92B' and received at button station 80. In certain
embodiments, user
settings 91 define characteristics for different modes of vibratory feedback.
Traffic states
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such as WALK or FLASHING/SOLID DON'T WALK may be associated with a
particular mode of vibratory feedback. Control signals 112 drive vibration
actuator 109 to
provide one mode of vibratory feedback (e.g. constant vibration) during a WALK
interval
(i.e. while a signal on line 92A' is being asserted), and another mode of
vibratory feedback
(e.g. 0.15 second of vibration every 1 second, or some other periodic
vibration) during a
FLASHING DON'T WALK or SOLID DON'T WALK interval (i.e. while a signal on line
92B' is being asserted).
[0038] To determine whether to enable output of control signal 112 to
vibration actuator
109, primary conflict monitor and error detector 102 may compare the actual
and expected
modes of vibratory feedback. This comparison may be performed each time the
current
traffic state changes. The actual mode of vibratory feedback may be determined
from
control signal 112. The expected mode of vibratory feedback may be determined
from
user settings 91 and the current traffic state (as ascertained from pedestrian
signals on
lines 92A', 92B'). If the actual and expected modes of vibratory feedback
match, primary
conflict monitor and error detector 102 causes relay 107 to be closed in
accordance with
control signal 112, enabling vibrotactile pedestrian signal output according
to the actual
and expected mode of vibratory feedback. In some embodiments primary conflict
and
error detector 102 causes relay 107 to be closed after a predetermined delay
time and may
maintain relay 107 in its closed position for a defined period. For example,
for the
FLASHING DON'T WALK or SOLID DON'T WALK mode, relay 107 may be closed
for a period equal to the DON'T WALK message duration plus a relay advance
time, and
is thereafter opened; this is repeated so long as the WALK traffic state is
not active and a
walk play_order state (a state set based on the order in which messages are to
be played,
as determined by user settings 91) is not active. For the WALK mode, relay 107
is closed
as long as certain conditions are true-e.g. the WALK traffic state is asserted
and
walk play_order state is active. In particular embodiments, such as the one
illustrated in
Figure 2, signals 112 are amplified by an amplifier 113 to provide suitable
signals to drive
vibration actuator 109.
[0039] A mismatch or difference between the actual and expected modes of
vibratory
feedback is indicative of a conflict or error. If there is a mismatch, relay
107 is maintained
in its default open position. Primary conflict monitor and error detector 102
may transmit
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an error message, providing information about the detected conflict or error,
via powerline
communications line 95 to an APS malfunction management subsystem 104
(described in
further detail below). Vibrotactile output may remain disabled until button
station 80's
operation is reset by service personnel.
[00401 APS generator 98 and primary conflict monitor and error detector 102
may be
implemented as software, hardware and/or a combination thereof. As illustrated
in Figure
2, APS generator 98 may comprise a processor 99 which executes instructions
provided
by software stored in a program memory 93 accessible by processor 99. As
illustrated in
Figures 2 and 4, primary conflict monitor and error detector 102 may comprise
a processor
110 which executes instructions provided by software stored in a program
memory 101
accessible by processor 110. Processors 99, 110 may comprise central
processing units
(CPUs), microprocessors, field programmable gate arrays (FPGAs), or any
combination
thereof, or any other suitable processing unit(s) comprising hardware and/or
software
capable of functioning as described herein.
[00411 As seen in Figure 4, software stored in program memory 101 may include
functions 115 to perform the conflict monitoring and error detection steps
described
above, such as:
= Function 115A for decoding an audio signal generated by APS generator 98
(e.g. to
extract sound header information).
= Function 115B for detecting a conflict or error with respect to an audio
signal (e.g. by
verifying the decoded sound header information for a sound file against the
current
traffic state and user settings, and identifying any mismatch in signal type
or sound
type).
= Function 115C for processing a vibrotactile control signal generated by APS
generator 98 (e.g. to determine the actual mode of vibratory feedback).
= Function 115D for detecting a conflict or error with respect to a
vibrotactile control
signal (e.g. by verifying the actual mode of vibratory feedback against the
expected
mode of vibratory feedback based on the current traffic state and user
settings, and
identifying any mismatch between the actual and expected modes of vibratory
feedback).
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= Function 115E for closing one or both of relays 106A, 106B if no conflict or
error is
detected by function 115B. Function 115E may determine which relays to close
and
the duration that the relays are to remain closed, based on decoded header
information
for a sound file 89.
= Function 115F for closing relay 107 if no conflict or error is detected by
function
115D.
= Function 115G for generating and transmitting an error message for each
conflict or
error detected by functions 115B or 115D.
[0042] Figures 6 and 7 illustrate methods 200 and 230, respectively, of
conflict monitoring
and error detection that may be performed by primary conflict monitor and
error detector
102. Method 200 verifies that pedestrian signals and audio control signals
satisfy certain
conditions prior to enabling output of the audio control signals to speakers
84, 86. Method
230 verifies that vibrotactile control signals satisfy certain conditions
prior to enabling
output of the vibrotactile control signals to vibration actuator 109.
[0043] Method 200 of Figure 6 begins at block 202 by receiving pedestrian
signals 201
and determining a current traffic state on the basis of pedestrian signals
201. If a valid
traffic state cannot be determined at block 202 from pedestrian signals 201,
method 200
proceeds to block 216. At block 216 output of audio control signals to
speakers 84, 86 is
disabled (and also output of vibrotactile control signals to vibration
actuator 109 may be
disabled), and an error message is optionally transmitted at block 218 to an
APS
malfunction management subsystem 104. However, if a valid traffic state can be
determined at block 202, method 200 proceeds to block 204 at which an audio
control
signal 203 is received and decoded.
[0044] At block 206, it is determined whether the decoding of audio control
signal 203
provides valid sound header information (e.g. identifying parameters of the
audible
pedestrian signal indication to be output at speakers 84, 86, such as an
actual signal type
and an actual sound type). If invalid sound header information is provided at
block 206,
output of audio control signals is disabled at block 216, and an error message
is optionally
transmitted at block 218 to APS malfunction management subsystem 104.
Otherwise,
method 200 proceeds to block 208 by retrieving sound user settings 205 from
memory.
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Sound user settings 205 may identify an expected signal type and sound type
associated
with the current traffic state determined at block 202.
[0045] At block 210, the expected signal type (as identified by sound user
settings 205 at
block 208) is compared with the actual signal type (as provided by the sound
header
information at block 206). If the expected and actual signal types differ,
output of audio
control signals is disabled at block 216, and an error message is optionally
transmitted at
block 218 to APS malfunction management subsystem 104. Otherwise, method 200
proceeds to block 212.
[0046] At block 212, the expected sound type (as identified by sound user
settings 205 at
block 208) is compared with the actual sound type (as provided by the sound
header
information at block 206). If the expected and actual sound types differ,
output of audio
control signals is disabled at block 216, and an error message is optionally
transmitted at
block 218 to APS malfunction management subsystem 104. Otherwise, method 200
proceeds by enabling output of audio control signal 203 to speakers 84, 86 at
block 214.
Output may be enabled for a period of time defined by the sound header
information
provided at block 206. Method 200 may repeat (commencing at block 202) for the
next
audio control signal 203 detected and received by primary conflict monitor and
error
detector 102.
[0047] In addition to performing method 200, primary conflict monitor and
error
detector 102 may perform method 230 of Figure 7. Method 230 begins at block
220 by
receiving pedestrian signals 201 and determining a current traffic state on
the basis of
pedestrian signals 201 (this step may use the current traffic state already
determined at
block 202 of method 200). At block 222, a vibrotactile control signal 207 is
received and
evaluated to determine an actual mode of vibratory feedback for the
vibrotactile pedestrian
signal indications to be provided by output of vibrotactile control signal 207
to vibration
actuator 109. At block 224, vibrotactile user settings 209 are retrieved from
memory.
Vibrotactile user settings 209 may identify an expected mode of vibratory
feedback
associated with the current traffic state determined at block 220.
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[0048] At block 226, the expected mode of vibratory feedback (as identified by
vibrotactile user settings 209 at block 224) is compared with the actual mode
of vibratory
feedback (as determined from the vibrotactile control signal 207 at block
222). If the
expected and actual modes of vibratory feedback differ, output of vibrotactile
control
signals is disabled at block 230, and an error message is optionally
transmitted at
block 232 to an APS malfunction management subsystem 104. Otherwise, method
230
proceeds by enabling output of vibrotactile control signal 207 to vibration
actuator 109 at
block 228. Method 230 may repeat (commencing at block 220) for the next
vibrotactile
control signal 207 detected and received by primary conflict monitor and error
detector 102. In particular embodiments, method 230 may repeat (commencing at
block 220) for the next vibrotactile control signal 207 which is detected and
received by
primary conflict monitor and error detector 102 after the current traffic
state has changed
(as it may suffice to verify only the first vibrotactile control signal 207
received during a
particular traffic interval, and not every vibrotactile control signal 207
generated for the
traffic interval).
[0049] System 100 may provide secondary conflict monitoring and error
detection. As
seen in Figure 1, a secondary conflict monitor and error detector 103 may be
implemented
by an APS malfunction management subsystem 104. Subsystem 104 may be housed
within a cabinet which houses traffic signal controller 90. Subsystem 104 may
handle
secondary conflict monitoring and error detection for all button stations 80
that are in
communication with traffic signal controller 90 (i.e. which is generally all
button
stations 80 located at a traffic intersection). Subsystem 104 may communicate
with traffic
signal controller 90 via a communications interface unit 120. Communications
interface
unit 120 processes and decodes information received by traffic signal
controller 90 over
powerline communications line 95. Communications interface unit 120 may
communicate
with traffic signal controller 90 by way of discrete digital inputs/outputs,
Ethernet, USB
(universal serial bus) connection, SDLC (synchronous data link communications)
interface, and the like. Communications interface unit 120 is not necessary
for all
communications. In some embodiments, subsystem 104 receives at least some
inputs
directly from traffic signal controller 90 (e.g. pedestrian signals carried
over lines 92A,
92B).
CA 02708109 2010-06-22
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[0050] Subsystem 104 receives input from a plurality of sources, and monitors
the
information received for conflict or error. If a conflict or error is detected
at an APS button
station 80, subsystem 104 responds accordingly. For example, for particular
conflicts or
errors, subsystem 104 inhibits output of audible and/or vibrotactile
pedestrian signal
indications at the APS button station 80 at which the conflict or error is
detected. In certain
embodiments, for some conflicts or errors, subsystem 104 may transmit inhibit
commands
via powerline communications line 95 to inhibit output of audible and/or
vibrotactile
pedestrian signal indications at the APS button station 80 at which the
conflict or error is
detected. For particular conflicts or errors, subsystem 104 may transmit
inhibit commands
via powerline communications line 95 to each APS button station 80 connected
to a traffic
signal controller 90, to inhibit output of audible and/or vibrotactile
pedestrian signal
indications at the button stations.
[0051] In particular embodiments, subsystem 104 receives and monitors the
following
inputs:
= Pedestrian signals carried over lines 92A, 92B, received via communications
interface
unit 120 (see Figures 1 and 5) (or directly from traffic signal controller 90
signal
outputs). Subsystem 104 may monitor current traffic state (e.g. WALK, FLASHING
DON'T WALK, or SOLID DON'T WALK) based on such pedestrian signals.
= Information from button station 80 carried over powerline communications
line 95,
received via communications interface unit 120 (see Figures 1 and 5). For
example,
primary conflict monitor and error detector 102 of button station 80 may
transmit the
following information about control signals 105 over powerline communications
line
95: button station 80's identification number (unique to each button station);
and
sound header information, such as for example, sound reference number, or
sound
code (sound type) and signal type. To avoid or reduce congestion on the
powerline
communications network, primary conflict monitor and error detector 102 may be
configured to transmit only the header information for each new sound file
(i.e. to
transmit only "new" sounds on the network). In certain embodiments, primary
conflict
monitor and error detector 102 may also periodically transmit information
about
vibrotactile control signals 112 over powerline communications line 95. For
example,
an identification of the actual mode of vibratory feedback to be provided by
output of
CA 02708109 2010-06-22
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vibrotactile control signal 112 may be transmitted each time the pedestrian
signal
status changes.
[0052] As seen in Figure 5, subsystem 104 may store a local copy of user
settings 91 for
each button station 80 in memory 116. This local copy may be updated each time
the user
settings 91 at a button station 80 are reconfigured or changed by service
personnel.
[0053] In certain embodiments, output of audible and/or vibrotactile
pedestrian signal
indications may be inhibited if subsystem 104 detects one or more of the
following
conflicts or errors:
= The signal type received over the powerline communications line 95 does not
match
the current traffic state.
= The sound type received over powerline communications line 95 does not match
the
sound type specified in user settings 91 for the current traffic state.
= The mode of vibratory feedback received over powerline communications line
95 does
not match the mode of vibratory feedback specified in user settings 91 for the
current
traffic state.
[0054] If one of the foregoing conflicts or errors is detected, subsystem 104
may inhibit
audible and vibrotactile output at the button station 80 where the conflict or
error is
detected. In some embodiments, depending on the severity and/or number of
occurrences
of the conflict or error detected, one or both of audible and vibrotactile
output at button
station 80 may be inhibited, or audible and/or vibrotactile output at button
stations 80
connected to a traffic signal controller 90 may be inhibited. The steps to be
taken may
allow for graceful degradation so that functional components may continue
operating-for
example, in particular embodiments, if the error or conflict occurs only once,
then only the
affected audible or vibrotactile output at the button station is inhibited;
however, if the
error or conflict is a repeat occurrence, then all audible or vibrotactile
output is inhibited at
the button station. The audible and/or vibrotactile outputs may remain
inhibited until
button station 80's operation is reset by service personnel.
[0055] In some embodiments, if a conflict or error is detected, subsystem 104
communicates an alarm or error message to a central traffic control
communications unit
CA 02708109 2010-06-22
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(not shown) via an Ethernet, hardware (e.g. digital output), or other
connection. In some
embodiments, subsystem 104 may cause other error-free button stations 80
within the
traffic intersection to play a "maintenance call" sound until button stations
80 are reset by
service personnel.
[00561 Subsystem 104 may be configured to maintain an event log. The event log
may
include normal events and errors. An error report may be generated and stored
in an event
log repository 121 each time subsystem 104 receives an error message from a
primary
conflict monitor and error detector 102 (as transmitted at block 218 of method
200 of
Figure 6 or block 232 of method 230 of Figure 7, for example) or each time
subsystem 104
has detected a conflict or error as described above. An error report may
include: time and
date of error; phase information for the button and intersection at the time
the error
occurred (e.g. WALK or DON'T WALK, or north-south or east-west crossing);
sound type
expected; sound type detected; button station identification number; and
button station
location.
[00571 Subsystem 104 may include a real-time clock 119 (see Figure 5) which
may be
used to provide a synchronization signal to the button stations 80 to
synchronize output of
audible pedestrian signal indications. Clock 119 may be used by button
stations 80 to
adjust the volume settings for the audible pedestrian signal indications
and/or inhibit
audible pedestrian signal indications at one or more speakers according to the
time of day.
Clock 119 may be used by button stations 80 to determine when to play special
alert
messages (e.g. alerts regarding construction or traffic patterns, AMBER alert
or emergency
alert messages, etc.) according to the time of day. Clock 119 may also provide
time-stamps
for event logging purposes.
[00581 Subsystem 104 may be implemented as software, hardware and/or a
combination
thereof. As illustrated in Figure 5, subsystem 104 may comprise a processor
118 which
executes instructions provided by software stored in a program memory 114
accessible by
processor 118. Processor 118 may comprise a central processing unit (CPUs),
one or more
microprocessors, one or more field programmable gate arrays (FPGAs), or any
combination thereof, or any other suitable processing unit(s) comprising
hardware and/or
software capable of functioning as described herein.
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[00591 Software stored in program memory 114 may include functions 117 to
perform the
conflict monitoring and error detection steps described above, such as:
= Function 117A for detecting a conflict or error with respect to a button
station 80's
audio or vibrotactile control signals.
= Function 117B for generating and recording an error report with respect to a
conflict or
error detected by function 117A.
= Function 117C for transmitting an alarm or error message to a central
traffic control
communications unit regarding a conflict or error detected by function 117A.
= Function 117D for inhibiting output of audible and/or vibrotactile
pedestrian signal
indications at the button station 80 where a conflict or error is detected by
function
117A.
[00601 Figure 8 illustrates a method 300 of conflict monitoring and error
detection that
may be performed by secondary conflict monitor and error detector 103, as
implemented
by APS malfunction management subsystem 104 of system 100. Method 300 may
provide
redundant conflict monitoring and error detection for system 100 for a button
station 80, in
conjunction with primary conflict monitor and error detector 102 implementing
methods
200 and 230 (Figures 6 and 7).
[00611 Method 300 begins at block 302 by determining a current traffic state
on the basis
of pedestrian signals 301 (either received as direct inputs from lines 92A,
92B or through a
communications interface unit). If no valid traffic state is determinable from
pedestrian
signals 301, method 300 proceeds to block 320 by inhibiting output of all
audible and
vibrotactile pedestrian signal indications at button stations 80 that are
affected, and
generating an error report at block 322 (and optionally transmitting the error
report to a
central traffic control communications unit).
[00621 If a valid current traffic state is determinable at block 302, method
300 proceeds by
receiving button station information at block 304. Button station information
may
comprise a button station identification number 303 identifying the button
station 80
which is transmitting the information to APS malfunction management subsystem
104. At
block 306, audio signal information (such as sound header information 305) is
received for
CA 02708109 2010-06-22
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an audio control signal generated for output to button station 80's speakers
84, 86. At
block 308, vibrotactile signal information (such as a mode of vibratory
feedback 307) may
be received for a vibrotactile control signal generated for output to button
station 80's
vibration actuator 109. Button station information, audio signal information,
and
vibrotactile signal information may be conveyed over powerline communications
line 95
to communications interface unit 120, which relays such information to APS
malfunction
management subsystem 104.
[0063] At block 310, method 300 proceeds by retrieving user settings 309
(including
audio and vibrotactile user settings) associated with the current traffic
state determined at
block 302. User settings 309 may be retrieved from memory accessible to APS
malfunction management subsystem 104 (such as memory 116 shown in Figure 5).
Method 300 then evaluates the actual parameters of the audible and
vibrotactile pedestrian
signal indications (as may be determined from the block 306 audio signal
information and
the block 308 vibrotactile signal information) against the expected parameters
of the
audible and vibrotactile pedestrian signal indications as identified by user
settings 309
associated with the current traffic state. For example, at block 312, method
300 compares
the actual and expected signal types for the audible pedestrian signal
indications. At
block 314, method 300 compares the actual and expected sound types for the
audible
pedestrian signal indications. At block 316, method 300 compares the actual
and expected
modes of vibratory feedback for the vibrotactile pedestrian signal
indications. If the actual
and expected parameters match, method 300 proceeds to block 318, at which APS
malfunction management subsystem 304 may wait for the next audio or
vibrotactile signal
information to be received (e.g. by way of communications interface unit 120).
[0064] If there is a difference between the actual and expected parameters at
any of blocks
312, 314, or 316, method 300 proceeds to block 320. At block 320, output of
all of the
affected audible and vibrotactile pedestrian signal indications may be
inhibited, regardless
of the conflict or error which led to block 320. In other embodiments, output
of one or
both of the audible and vibrotactile pedestrian signal indications may be
inhibited,
depending on the conflict or error which led to block 320 (e.g. an invalid
traffic state at
block 302 may result in inhibition of all affected audible and vibrotactile
pedestrian signal
indications, whereas an error in audible pedestrian signal indications at
blocks 312 or 314
CA 02708109 2010-06-22
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may result in inhibition of affected audible pedestrian signal indications
only). An error
report is generated at block 322 (and optionally transmitted to a central
traffic control
communications unit).
[00651 Method 300 may repeat (commencing at block 302) each time new
information is
received through communications interface unit 120.
[00661 In other embodiments, method 300 may be implemented as part of a
conflict
monitoring and error detection system 100 which does not include a primary
conflict
monitor and error detector 102 performing the methods of 200 and 230 at button
station 80. For example, APS generator 98 (or another suitable component at
button
station 80) may be adapted to provide information about audio and vibrotactile
control
signals over powerline communications line 95 for verification by APS
malfunction
management subsystem 104 using method 300.
[00671 Where a component (e.g. module, processor, controller, server, circuit,
interface,
device, amplifier, etc.) is referred to above, unless otherwise indicated,
reference to that
component (including a reference to a "means" should be interpreted as
including as
equivalents of that component any component which perform the function of the
described
component (i.e., that is functionally equivalent), including components which
are not
structurally equivalent to the disclosed structure which perform the function
in the
illustrated exemplary embodiments of the invention.
[00681 Conflict monitoring and error detection system 100 and components
thereof may
be configured to perform a method according to the embodiments described
herein. For
example, primary conflict monitor and error detector 102 (Figure 4) may
implement
methods 200 and 230 (Figures 6 and 7) by executing software instructions
provided by
functions 115. Secondary conflict monitor and error detector 103 (Figure 5)
may
implement method 300 (Figure 8) by executing software instructions provided by
functions 117. Particular embodiments may also be provided in the form of a
program
product. The program product may comprise any medium which carries a set of
computer-readable signals comprising instructions which, when executed by a
data
processor, cause the data processor to execute a method of the invention.
Program
CA 02708109 2010-06-22
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products according to the invention may be in any of a wide variety of forms.
The program
product may comprise, for example, physical media such as magnetic data
storage media
including floppy diskettes, hard disk drives, optical data storage media
including CD
ROMs, DVDs, electronic data storage media including ROMs, flash RAM, or the
like.
The computer-readable signals on the program product may optionally be
compressed or
encrypted.
[0069] While a number of exemplary aspects and embodiments have been discussed
above, those of skill in the art will recognize certain modifications,
permutations,
additions and sub-combinations thereof. For example:
= In some embodiments, conflict monitoring and error detection system 100 may
comprise only a primary conflict monitor and error detector 102 (provided
within each
button station 80), without a secondary conflict monitor and error detector
103.
= In other embodiments, conflict monitoring and error detection system 100 may
comprise a conflict monitor and error detector 103 implemented by an APS
malfunction management subsystem 104, without a primary conflict monitor and
error
detector 102 as described herein. A processor may be provided at each button
station 80 to receive control signals generated by APS generator 98 for
driving
speakers 84, 86 and vibration actuator 109. Such processor may decode or
process the
control signals (e.g. so as to extract the sound header information for an
audible
control signal and to determine the mode of vibratory feedback for a
vibrotactile
control signal) and transmit the decoded information to APS malfunction
management
subsystem 104 for verification against the current traffic state and user
settings.
= The APS systems described herein include a button speaker 84 and an overhead
speaker 86. In other embodiments, different combinations of speakers may be
provided. Conflict monitoring and error detection system 100 may be adapted to
control output for different combinations of speakers.
= Processors 99, 110 may be substituted with a single processor or control and
processing unit capable of providing the signal generation, conflict and error
detection,
and output control functions described herein.
= Communications interface unit 120 may receive signals from traffic signal
controller 90 indicating special events, such as, for example: train
approaching,
emergency vehicle approaching, new construction or traffic patterns, AMBER
alert or
CA 02708109 2010-06-22
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emergency alerts, etc. Upon receiving such signals, communications interface
unit 120
may send a request to button station 80 to generate audible alert messages.
The alert
messages may be preloaded in button station 80 or may be downloaded (from
communications interface unit 120, for example) to button station 80 over
powerline
communications line 95.
= Prior to deployment and from time to time, secondary conflict monitor and
error
detector 103 may be run through a series of tests to verify that the unit is
operating
normally. To run such tests, verification software may be provided on a
computer or
hardware device which is connected to secondary conflict monitor and error
detector
103; the software may send test signals to secondary conflict monitor and
error
detector 103 and record and verify the response.
= In some embodiments, one or more of the relays used to control audible or
vibrotactile
output (e.g. relays 106, 106A, 106B and/or 107) may be placed in a closed
(operative)
position as the default position. When one or more errors or conflicts are
detected, the
relay may be switched to an open (inoperative) position until the error or
conflict is
resolved.
It is therefore intended that the following appended claims and claims
hereafter introduced
are interpreted to include all such modifications, permutations, additions and
sub-combinations as are within their true spirit and scope.
