GB2537132A

GB2537132A - Pedestrian crossing control method and apparatus

Info

Publication number: GB2537132A
Application number: GB1505917.3A
Authority: GB
Inventors: Hoslett David; Manston Keith; Geoffrey Rhodes Antonio
Original assignee: Siemens PLC
Current assignee: Siemens PLC
Priority date: 2015-04-08
Filing date: 2015-04-08
Publication date: 2016-10-12
Also published as: GB2539077A; GB201505917D0; GB2539077B

Abstract

A means for controlling a pedestrian crossing comprising a kerbside radar detector arranged to detect the presence of one or more pedestrians in a waiting area. A crossing controller is connected to receive signals from the kerbside radar detector and to control generation of safe-to-cross signals. The crossing controller is operable, in dependence on the volume of pedestrians detected in the waiting area by the kerbside radar, to provide a crossing priority balance between vehicle traffic and pedestrian traffic. The crossing priority balance may be adjusted through alterations to pedestrian inter-green periods or to the duration of safe-to-cross signals.

Description

PEDESTRIAN CROSSING CONTROL METHOD AND APPARATUS

The present invention is directed to methods and apparatus for controlling pedestrian crossings at traffic lights.

Typically, a stand-alone pedestrian crossing, or a pedestrian crossing built into a traffic light controlled junction includes a pedestrian-operated signalling unit such as a pushbutton which signals to a control system that a pedestrian is waiting to cross. The control system takes this into account and provides a light, and also optionally a sound and/or tactile, signal indicating to the pedestrian that it is safe to cross, when other signals to operators of vehicles indicate that they should not proceed along the stretch of road used as teh pedestrian crossing.

Preoblems with such a simple arrangement include that acertain fixed period may be provides for pedestrians to cross. This may bot be enough time if a large group of pedestrians has gathered to cross. On the other hand, if only a single pedestrian is waiting, the fixed period may be excessively long, leading to driver frustration. This is particularly the case when a pedestrian presses the push button but does not wait for the signal before crossing, forcing drivers to wait while the pedestrian crossing displays a "safe-to-cross" signal to no pedestrians.

There have been provided sensors which detect whether at least one pedestrian is present in a waiting area for the crossing. An example of this is the HEIMDALL detector by Siemens. This is a RADAR detector which senses whether there is a pedestrian in a designated waiting area, defined by the sensor. Where no pedestrian is detected, the "safe-to-cross" signal may be reduced in duration, delayed, or omitted entirely.

On the other hand, a large group of pedestrians may be wait-ing to cross. In this case, it may be best to extend, and/or bring forward the "safe-to-cross" signal, to improve the rate of crossing of pedestrians, and reduce the temptation on pedestrians to cross when the signal is not in their favour.

Some attempts at such controls have been made in the past. For example, pneumatic pads have been placed in pavements to give an indication of the presence of at least one pedestrian, but these pneumatic pads have been found to require a significant amount of maintenance and replacement. Alterna-tively, cameras have been used to capture an image of waiting pedestrian(s), to detect their number, and to adjust the priority of the "safe-to-cross" signal accordingly. However, it has been found that such cameras are expensive to install and maintain, and the capture of visible images may be resented by the public. The visible image capture may also be hampered by adverse weather conditions, such as fog, snow, heavy rain. Also, changing lighting levels may mean unreliable detection at certain times of night or day.

The present invention seeks to provide methods an apparatus for distinguishing the presence of one pedestrian, multiple pedestrians or an absence of pedestrians, to provide a corresponding signal to a controller of a pedestrian crossing such that the priority of a "safe-to-cross" signal may be ad-justed, for example by extending or reducing its duration, by delaying or advancing it or by reducing the pedestrian "inter-green" period, such that the "safe-to-cross" signal may be given more times in a determined length of time.

The present invention accordingly provides methods and apparatus as defined in the appended claims.

The above, and further, objects, characteristics and advan5 tages of the present invention will become more apparent from the following description of certain embodiments thereof.

In particular, the present invention provides a method to increase priority of pedestrians relative to traffic at pedestrian crossings as waiting area pedestrian volume increases, as detected by pedestrian kerbside RADAR detectors.

Preferably, conventional RADAR sensors are used, such as those employed in existing Siemens HEIMDALL detectors for pe-destrian crossings. Such RADAR detectors have advantages over the alternatives discussed above at least in that they do not require as regular maintenance, having no moving parts; they are relatively immune to adverse weather; and they do not capture visible images which could be used to identify a pedestrian.

The apparatus of the present invention uses a volumetric pedestrian detection using RADAR. A certain steady-state RADAR signal will be detected representing a waiting area in "view" of the RADAR detector. When this steady-state signal is disturbed, the conventional system interprets the disturbance as indicating the presence of one or more pedestrians waiting for the "safe-to-cross" signal.

In an improvement to this conventional technique, the inventors have developed a method to assess the volume of tar-get(s) in the waiting area. This may be achieved using a range of mathematical techniques such as FFT, integration, binning and threshold hysteresis. The inventors have found that application of such techniques to a conventional FMCW RADAR device/detector, can assess a volume of multiple targets, assumed to be pedestrians, in the waiting area.

The assessed volume is then communicated to a traffic controller. The traffic controller is then pre-programmed with one of a range of strategies that makes use of the volume information provide. A large measured volume will be taken to represent a large number of pedestrians waiting to cross. For example, a higher priority may be given to a large volume of pedestrians, for example by extending the duration of the "safe-to-cross" signal, or reducing the pedestrian inter-green period between "safe-to-cross" signals, so giving less time to vehicle traffic. Pedestrian crossings may have a flashing-green phase, indicating to pedestrians that they should not begin to cross, but may continue to cross if they have started. This phase may be extended to allow a rela-tively large number of pedestrians to cross during a single cycle of the pedestrian crossing yet introducing a clear interruption to a flow of pedestrians such that vehicle traffic may take its turn to proceed.

A rage of different pedestrian volumes may be defined to provide a corresponding range of strategies: typically reducing the pedestrian inter-green period and/or increasing the duration of the "safe-to-cross" signal for larger detected vol-umes of pedestrians.

The reaction of the crossing control system may be tailored according to a customer's needs, the present invention providing a RADAR sensor for detecting a volume of pedestrians in a waiting area and providing a corresponding signal to the crossing control system.

Thresholds for adjustment to inter-green times of duration of 5 "safe-to-cross" signals may be determined, or these paramaters may be adjusted proportionately to the detected volume.

The inventors have provided algorithms for use on a RADAR detection platform to determine the likely volume of pedestri-ans waiting to cross a pedestrian crossing and communicating this to the controller. The controller then adjusts operation of the crossing according to the determined volume.

In an example embodiment, a RADAR-based kerbside detector is used to indicate to a traffic controller operating a vehicle actuated mode an estimate of the volume of pedestrians in the pedestrian waiting area. The controller then uses this information such that the controller can curtail vehicle phase extensions and/or extend vehicle inter-green times to give pedestrians increased priority over traffic, relative to the estimated volume.

The RADAR kerbside detector may provide signals according to two defined thresholds, to indicate a determined volume of pedestrians.

For example, where no pedestrians are detected, both signals output 1 and output 2 may be LOW. Where a pedestrian volume is detected sufficient to indicate at least one but no more than three pedestrians, output 1 may return a HIGH value while output 2 returns a LOW value. Where a pedestrian vol- ume is detected sufficient to indicate at least four but no more than seven pedestrians, output 1 may return a LOW value while output 2 returns a HIGH value. Where a pedestrian vol-ume is detected sufficient to indicate more than seven pedestrians, both output 1 and output 2 may return HIGH values. Of course, other thresholds and encoding schemes may be provided within the scope of the present invention.

Prefereably, the detector also returns a conventional detect/no detect signal indicating whether at least one pedestrian is detected, maintaining backwards compatibility with existing systems. Such output may be a voltage Level or an impedance output as is conventional.

In an example system, the occupancy of the detection zone, being the pedestrian waiting area, is determined by the density of pedestrians as indicated by the number of Fast Fourier Transform bins that are currently in detect, in conjunction with the relative amplitude of said bins as compared to the overall threshold -the Bin Density. A bin Density Weighting may be determined dynamically by the detector and applied to each bin to normalise the signal levels and thresholds across the near and far zones. Hysteresis and sample-and-hold periods are used to smooth transactions be-tween the occupancy levels. The crossing controller takes the occupancy level as indicted by the two detector signals (output 1 and output 2) and curtails vehicle phase extensions or extends vehicle inter-green times to give pedestrians increased priority over vehicle traffic, as required.

The present invention is believed to be the first to offer kerbside RADAR detection of pedestrian volume to enable a controller to provide the appropriate crossing priority balance between vehicle traffic and pedestrian traffic.

The combination of Zone Saturation and Bin Density provides a 30 measure of zone occupancy from the kerbside radar detector. The two signals described may be used to operate relays or other appropriate devices to provide indication of NONE/LOW/MEDIUM/HIGH occupancy. The summation of the nor-mally-closed and common lines of the relays may be used to provide a conventional detect/no detect function.

Claims

CLAIMS: 1. Apparatus for controlling a pedestrian crossing comprising: -a kerbside RADAR detector arranged to detect the presence of one or more pedestrians in a waiting area; -a crossing controller connected to receive signals from the kerbside RADAR detector and to control generation of a safeto-cross signal accordingly, wherein the kerbside RADAR detector generates signals indicating a volume of pedestrians located in the waiting area, and the crossing controller provides an appropriate crossing priority balance between vehicle traffic and pedestrian traffic, dependent on the indicated volume of pedestrians wait-ing.
2. Apparatus according to claim 1 wherein the crossing con-troller adjusts the pedestrian inter-green period according to the indicated volume of pedestrians waiting.
3. Apparatus according to any preceding claim wherein the crossing controller adjusts the duration of the safe-to-cross signal according to the indicated volume of pedestrians waiting.
4. Apparatus according to any preceding claim wherein the kerbside RADAR detector provides signals to the crossing con-25 troller according to comparison between a detected volume of pedestrians and one or more thresholds.
5. Apparatus according to claim 4 wherein two thresholds are used, and the signals are defined to indicate pedestrian volumes NONE/LOW/MEDIUM/HIGH.
6. A method for controlling a pedestrian crossing comprising: -detecting the presence of one or more pedestrians in a waiting area using a kerbside RADAR detector; -receiving signals from the kerbside RADAR detector in a crossing controller, and controlling generation of a safe-tocross signal accordingly, wherein the kerbside RADAR detector generates signals indicating a volume of pedestrians located in the waiting area, and the crossing controller provides an appropriate crossing priority balance between vehicle traffic and pedestrian traffic, dependent on the indicated volume of pedestrians waiting.
7. A method according to claim 6 wherein the crossing con-troller adjusts the pedestrian inter-green period according to the indicated volume of pedestrians waiting.
8. A method according to claim 6 or claim 7 wherein the crossing controller adjusts the duration of the safe-to-cross signal according to the indicated volume of pedestrians wait-20 ing.
9. A method according to any of claims 6-8 wherein the kerbside RADAR detector provides signals to the crossing controller according to comparison between a detected volume of pedestrians and one or more thresholds.
10. Apparatus according to claim 9 wherein two thresholds are used, and the signals are defined to indicate pedestrian volumes NONE/LOW/MEDIUM/HIGH.AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS CLAIMS: 1. Apparatus for controlling a pedestrian crossing comprising: -a kerbside RADAR detector arranged to detect the presence of one or more pedestrians in a waiting area; -a crossing controller connected to receive signals from the kerbside RADAR detector and to control generation of a safeto-cross signal accordingly, wherein the kerbside RADAR detector generates signals indicating a volume of pedestrians located in the waiting area, and the crossing controller provides a crossing priority bal-co ance between vehicle traffic and pedestrian traffic, dependent on the indicated volume of pedestrians waiting, CD 15 characterised in that the occupancy of the waiting area is determined by the density of pedestrians as indicated by aCDnumber of Fast Fourier Transform bins in detect, in conjunc-tion with the relative amplitude of said bins as compared to an overall threshold.2. Apparatus according to claim 1 wherein a Bin Density Weighting is determined dynamically by the detector and applied to each bin to normalise the signal levels and thresholds across near and far zones.3. Apparatus according to claim 1 or claim 2 wherein hys-teresis and sample-and-hold periods are used to smooth transactions between the occupancy levels.4. Apparatus according to any preceding claim wherein the crossing controller adjusts the pedestrian inter-green period according to the indicated volume of pedestrians waiting.S. Apparatus according to any preceding claim wherein the crossing controller adjusts the duration of the safe-to-cross signal according to the indicated volume of pedestrians waiting.6. Apparatus according to any preceding claim wherein the kerbside RADAR detector provides signals to the crossing controller according to comparison between a detected volume of pedestrians and one or more thresholds.7. Apparatus according to claim 6 wherein two thresholds 10 are used, and the signals are defined to indicate pedestrian volumes NONE/LOW/MEDIUM/HIGH.8. A method for controlling a pedestrian crossing compris-cr) ing: -detecting the presence of one or more pedestrians in a 0.1 15 waiting area using a kerbside RADAR detector; -receiving signals from the kerbside RADAR detector in a crossing controller, and controlling generation of a safe-tocross signal accordingly, wherein the kerbside RADAR detector generates signals indi-cating a volume of pedestrians located in the waiting area, and the crossing controller provides an appropriate crossing priority balance between vehicle traffic and pedestrian traffic, dependent on the indicated volume of pedestrians waiting, characterised in that the occupancy of the waiting area is determined by the density of pedestrians as indicated by a number of Fast Fourier Transform bins in detect, in conjunction with the relative amplitude of said bins as compared to an overall threshold.9. A method according to claim 8 wherein a Bin Density Weighting is determined dynamically by the detector and applied to each bin to normalise the signal levels and thresholds across near and far zones.10. A method according to claim 8 or claim 9 wherein hysteresis and sample-and-hold periods are used to smooth transactions between the occupancy levels.
11. A method according to any of claims 8-10 wherein the crossing controller adjusts the pedestrian inter-green period 10 according to the indicated volume of pedestrians waiting.
12. A method according to any of claims 8-11 wherein the crossing controller adjusts the duration of the safe-to-cross signal according to the indicated volume of pedestrians waiting.CNJ 15
13. A method according to any of claims 8-12 wherein the CD kerbside RADAR detector provides signals to the crossing con-troller according to comparison between a detected volume of O pedestrians and one or more thresholds.
14. A method according to claim 13 wherein two thresholds 20 are used, and the signals are defined to indicate pedestrian volumes NONE/LOW/MEDIUM/HIGH.