CA2881882C - Method for controlling a prepare-to-stop panel - Google Patents

Abstract

The method for controlling the Prepare-To-Stop panel can include the steps of: activating the plurality of lamps of the Prepare-To-Stop panel a given period of time prior to a change of the traffic lights from green to yellow; during said activation of the plurality of lamps, monitoring at least a given one of the plurality of lamps to detect malfunction thereof; upon detecting a malfunction of the given one of the lamps, generating a malfunction signal.

Description

METHOD FOR CONTROLLING A PREPARE-TO-STOP PANEL
BACKGROUND
[0001] Prepare-to-stop panels, often referred to as PTS panels in the art, are commonly used throughout North America. Prepare-to-stop panels are typically provided at a given distance ahead of an associated set of traffic lights on roads having a speed limit above 50km/h, and typically include two lamps which are operable in an alternating flashing manner for a given period of time preceding the change from the "green" state to the "yellow"
state, to warn incoming traffic of an imminent change, allowing traffic to prepare to stop at the traffic light. Accordingly, the PTS panel faces a direction of an incoming path of traffic flow, and its distance from the traffic lights which is typically based on the speed limit and the given period of time preceding the change of state of the traffic light.

[0002] Although PTS panel controlling methods were satisfactory to a certain degree, there remained room for improvement.
SUMMARY

[0003] There is provided a method for controlling a PTS panel which can detect a malfunction of one or more of the lamps and generate a malfunction signal accordingly. The malfunction signal can be used to automatically send a call to a control center for maintenance, can be used to trigger a different form of activation of the PTS
panel, such as a simultaneously flashing mode, used to force the traffic lights to change to a red/yellow flashing state, or used to store a measured value into a memory, to name a few examples.

[0004] In accordance with one aspect, there is provided a method for controlling a Prepare-To-Stop panel being associated to a set of traffic lights, the Prepare-To-Stop panel having a plurality of lamps; the method comprising the steps of: activating the plurality of lamps of the Prepare-To-Stop panel; during said activation of the plurality of lamps, monitoring at least a given one of the plurality of lamps to detect malfunction thereof; upon detecting a malfunction of the given one of the lamps, generating a malfunction signal.

[0005] In accordance with another aspect, there is provided a device for analyzing a Prepare-To-Stop (PTS) panel having a plurality of lamps, the system comprising: a processor for receiving an activation signal from a traffic lights module for and activating the plurality of lamps of the PTS panel with an AC current mains upon reception of the activation signal; at least a sensor for measuring a plurality of AC current values associated to a corresponding lamp of the plurality of lamps while activated, the processor comparing each of the plurality of AC current values to a current threshold and identifying which of the plurality of lamps is broken based on said comparison

[0006] Many further features and combinations thereof concerning the present improvements will appear to those skilled in the art following a reading of the instant disclosure.
DESCRIPTION OF THE FIGURES

[0007] In the figures,

[0008] Fig. 1 is a schematic diagram illustrating a first example of a device for analyzing a PTS panel;

[0009] Fig. 2 is a schematic diagram illustrating a second example of a device for analyzing a PTS panel;

[0010] Fig. 3 is a block diagram illustrating steps of a method for analyzing a PTS panel;
and

[0011] Fig. 4 is an example configuration of a PTS panel and a traffic light system.
DETAILED DESCRIPTION

[0012] Fig. 1 is a schematic diagram illustrating a first example of a device 110 for controlling a PTS panel 112. As it can be seen from a broad point of view, the device 110 is provided in the form of a PTS module which receives power by way of an AC
mains 114 providing an AC current and also receives an activation signal 116 associated to the traffic lights . When the device 110 receives the activation signal, the device provides electrical power to the PTS panel 112 having a plurality of lamps 118. The type of electrical power provided to the PTS panel depends on the type of lamps therein. Upon activation of the lamps 118 of the PTS panel 112, the lamps light towards an incoming path of traffic flow in order to advise an incoming driver that he will imminently have to stop.

[0013] More specifically, in this embodiment, the device 110 has a processor 120 directly or indirectly connected to the traffic lights activation signal 116 for receiving the activation signal therefrom. Moreover, the processor 120 can activate the plurality of lamps 118 of the PTS panel 112 with the AC current mains 114 upon reception of the activation signal. The device 110 also includes at least a sensor (two sensors 112' and 112" are illustrated in Fig.1, for instance, to obtain independent indications for each one of the two lamps ¨though alternate embodiments can have a single sensor for all lamps, for instance) for obtaining an indication of power consumption associated to a corresponding lamp (this can be done by measuring current and voltage simultaneously during activation of the lamp, for instance). In this example, the processor compares each of the indications of power consumption to a power consumption threshold. If the comparison yields a result where the power consumption is below the power consumption threshold, the processor can generate a malfunction signal 117, which can be used in various ways

[0014] Still referring to Fig. 1, the processor 120 controls the AC mains 114 to power each one of the plurality of lamps 118 via triacs 124' and 124". Indeed, when the device 110 receives the activation signal, it can provide just enough current to the transistors 124', 124"
switch to conduct the electrical power independently to the lamps 118. For instance, the typical AC current can be 110 VCA at a frequency of 60 Hz. Moreover, the device can be made of an exemplary material such as anodized aluminium or stainless steel.
Also, the circuits and electronic components can be covered by a passivation layer.

[0015] Fig. 2 is a schematic diagram illustrating a second example of a device 210 for analyzing a PTS panel 212. The second example shows the device 210, the PTS
panel 212, a traffic lights module 216, an AC mains 214, and a plurality of light-emitting diodes (LED) lamps 218', 218" of the PTS panel 212 (although more than two LED lamps can be provided). The device 210 includes a switch-mode converter 226 which redresses the AC
current with a rectifier 228 and then filter the resulting signal with an electrical filter 230 to convert the AC current of the AC mains to a DC current, since LED lamps requires DC

current for powering. In this example, the device 210 activates the LED lamps 218', 218"
using triodes switches 224', 224" for alternating current (TRIAC) between the converted AC
mains and the PTS panel 212. Similarly to the first example, a processor 220 can also control the activation of the LED lamps 218', 218" based on an activation signal to be received by the traffic lights module 216. Moreover, a plurality of sensors are incorporated in the processor (not shown).

[0016]
It may be convenient for the PTS panel to sequentially and separately activate each one of the plurality of lamps of the PTS panel in a pattern having a pattern period. In other words, if the PTS panel 212 has two LED lamps, a first LED lamp 218' can be activated for a half of the pattern period (1 s, for instance) while a second LED lamp 218" is not activated. After the first half of the pattern period, the second LED lamp 218" can be activated while the first LED lamp 218' is not. When the pattern is repeated along the duration of the step of activating the plurality of lamps, the LED lamps 218', 218" of the PTS
panel 212 can appear to flash continuously. Since flashing and/or blinking lamps tend to attract the attention of the drivers, it enhances security for the drivers.
Although an example of a PTS panel having two LED lamps has been described, the PTS panel can have more than two lamps, such as three, four, etc. Moreover, in alternate embodiments, the pattern period can differ.

[0017] With such an embodiment, AC current values may not be biased by the switch-mode conversion performed by the switch-mode converter 226. In order to limit the bias introduced in the measurement of the AC current values, the plurality of AC
current values can be converted to a plurality of power consumed values each based on a corresponding voltage value measured at a corresponding one of the plurality of LED lamps.
Afterwards, the processor 220 of the device 210 can compare the plurality of power consumed values to a power threshold. By using the power consumed values instead of the AC
current values, biases can be avoided which can provide more accuracy in determining if a lamp is broken or not.

[0018] In the second example of the device 210, the AC current values can be integrated using a plurality of integrators 232 (represented by the ampli-ops and the resistors therearound) which integrates the AC current values over a fraction of the pattern period to obtain a plurality of integrated AC current values. Each integrated AC current values can then be compared to a fractioned threshold within one pattern period. By doing so, the plurality of lamps can be compared and identified as broke, if it is the case, at each one of the pattern period.

[0019] A typical LED lamp for a PTS panel can normally operate at 8-12 Watts, for instance. The power threshold value can be set to a fixed value corresponding to fraction of this, such as 25 or 30 % for instance. Accordingly, the power threshold value can be set at 3 Watts for instance. Alternately, a learning feature can be incorporated into the processor and the actual operating power can be measured and stored into a memory, say, upon activation of a button and/or periodically during a period of use of the PTS panel. In the latter case, the power threshold value can correspond to a given percentage of depletion from an initially measured state, for instance. It the processor powers the lamps via corresponding triacs, the triacs can be used to determine when a corresponding one of the lamps is actually powered (i.e. in its intermittent powered state). The processor can thus be programmed to obtain the indication of power consumption during that period. Ideally, the indication of power consumption is further taken for a given period, and after a given amount of time has elapsed since the powering, i.e. once the power consumption initial peak has passed and once the power consumption is relatively constant.

[0020] Fig. 3 shows a block diagram illustrating the steps of a method 300 for analyzing a PTS panel. The method can include receiving an activation signal indicative that the traffic light will turn to red in a given period of time and therefore, the activation signal triggering a step 304 of activating the lamps of the PTS panel. During each activation of the lamps of the PTS panel, a step 306 of monitoring at least one of the lamps can be performed. A
malfunction signal is generated if a malfunction is detected. The malfunction signal can be sent to a control center which, when it receives such a system error, can appropriately react and change the damaged lamps, or can be used for any alternate suitable use such as triggering a simultaneous flashing mode of the PTS panel, storing data into a memory, etc.

[0021] As can be understood, the examples described above and illustrated are intended to be exemplary only. For instance, in alternate embodiments, the lamps can be other than LED lamps, can be powered using AC or DC current, and the particulars of the power consumption detection can be adjusted accordingly. The scope is indicated by the appended claims.

Claims (16)

WHAT IS CLAIMED IS:

1. A method for controlling a Prepare-To-Stop panel being associated to a set of traffic lights, the Prepare-To-Stop panel having a plurality of lamps; the method comprising the steps of:
activating the plurality of lamps of the Prepare-To-Stop panel;
during said activation of the plurality of lamps, monitoring at least a given one of the plurality of lamps to detect malfunction thereof, the monitoring comprising;
obtaining an indication of a power consumption of the given one of the lamps during said activation;
comparing the obtained power consumption indication to a power consumption threshold value;
detecting a presence of a malfunction upon determining that the obtained power consumption is below the power consumption threshold value; and upon detecting a malfunction of the given one of the lamps, generating a malfunction signal, wherein said obtaining further comprises measuring an AC current value provided to the given one of the lamps, measuring a voltage value of the given one of the lamps, and converting the AC current value and the voltage value into a power consumption value, and wherein the measuring of the AC current includes integrating a measured current value over a fraction of a pattern period of the AC current.

2. The method of claim 1, wherein said activating further comprises powering the given one of the plurality of lamps with a DC current converted from an AC current mains.
Date Recue/Date Received 2023-03-30

3. The method of claim 1 wherein the activating includes powering the given one of the lamps intermittently, and wherein said indication is obtained at least once when the given one of the lamps is powered.

4. The method of claim 3 wherein said obtaining is performed for a given period of time, once a power consumption of the given one of the lamps has stabilized.

5. The method of claim 1 further comprising storing the indication of a power consumption to a memory.

6. The method of claim 5 wherein the storing is performed upon generation of the malfunction signal.

7. The method of claim 5 wherein the monitoring of the plurality of lamps further comprises determining the power consumption threshold value based on the stored indication of power consumption.

8. The method of any one of claims 1 to 7, wherein said activating further comprises sequentially and separately powering each one of the plurality of lamps in a pattern having a given pattern period.

9. The method of claim 1 wherein the plurality of lamps include at least two lamps which operate alternately during said activation, in associated successive periods of time; further comprising associating given ones of the periods of time to the given one of the 2 lamps and independently determining a state of function or malfunction for each one of the 2 lamps.

10. The method of claim 9 further comprising obtaining an independent indication of a power consumption of each one of the lamps during said activation.

11. The method of claim 10 wherein the monitoring of the plurality of lamps further includes, for each one of the lamps : comparing the associated obtained power consumption indication to an associated power consumption threshold value; and detecting a presence of an associated malfunction upon determining that the Date Recue/Date Received 2023-03-30 associated obtained power consumption is below the associated power consumption threshold value.

12. The method of claim 11 further comprising associating the malfunction signal to the given one of the lamps.

13. The method of any one of claims 1 to 12 wherein the plurality of lamps are a plurality LED lamps.

14. The method of any one of claims 1 to 13 further comprising advising a control center of a malfunction based on the malfunction signal.

15. The method of claim 1 wherein the activating is performed a given period of time prior to a change of the traffic lights from green to yellow.

16. The method of claim 1, wherein the malfunction signal forces the set of traffic lights to change state.
Date Recue/Date Received 2023-03-30