GB2589984A - Radar apparatus - Google Patents

Radar apparatus Download PDF

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Publication number
GB2589984A
GB2589984A GB2018131.9A GB202018131A GB2589984A GB 2589984 A GB2589984 A GB 2589984A GB 202018131 A GB202018131 A GB 202018131A GB 2589984 A GB2589984 A GB 2589984A
Authority
GB
United Kingdom
Prior art keywords
crossing
target
processing circuit
above ground
detection system
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
GB2018131.9A
Other versions
GB202018131D0 (en
Inventor
Amsdon Lyndon
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
AGD Systems Ltd
Original Assignee
AGD Systems Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by AGD Systems Ltd filed Critical AGD Systems Ltd
Publication of GB202018131D0 publication Critical patent/GB202018131D0/en
Publication of GB2589984A publication Critical patent/GB2589984A/en
Pending legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/06—Systems determining position data of a target
    • G01S13/42—Simultaneous measurement of distance and other co-ordinates
    • G01S13/44—Monopulse radar, i.e. simultaneous lobing
    • G01S13/4454—Monopulse radar, i.e. simultaneous lobing phase comparisons monopulse, i.e. comparing the echo signals received by an interferometric antenna arrangement
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/06—Systems determining position data of a target
    • G01S13/08—Systems for measuring distance only
    • G01S13/32—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
    • G01S13/34—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/50—Systems of measurement based on relative movement of target
    • G01S13/52—Discriminating between fixed and moving objects or between objects moving at different speeds
    • G01S13/56—Discriminating between fixed and moving objects or between objects moving at different speeds for presence detection
    • G—PHYSICS
    • G08—SIGNALLING
    • G08G—TRAFFIC CONTROL SYSTEMS
    • G08G1/00—Traffic control systems for road vehicles
    • G08G1/005—Traffic control systems for road vehicles including pedestrian guidance indicator
    • G—PHYSICS
    • G08—SIGNALLING
    • G08G—TRAFFIC CONTROL SYSTEMS
    • G08G1/00—Traffic control systems for road vehicles
    • G08G1/01—Detecting movement of traffic to be counted or controlled
    • G08G1/0104—Measuring and analyzing of parameters relative to traffic conditions
    • G08G1/0108—Measuring and analyzing of parameters relative to traffic conditions based on the source of data
    • G08G1/0116—Measuring and analyzing of parameters relative to traffic conditions based on the source of data from roadside infrastructure, e.g. beacons
    • G—PHYSICS
    • G08—SIGNALLING
    • G08G—TRAFFIC CONTROL SYSTEMS
    • G08G1/00—Traffic control systems for road vehicles
    • G08G1/01—Detecting movement of traffic to be counted or controlled
    • G08G1/0104—Measuring and analyzing of parameters relative to traffic conditions
    • G08G1/0125—Traffic data processing
    • G08G1/0133—Traffic data processing for classifying traffic situation
    • G—PHYSICS
    • G08—SIGNALLING
    • G08G—TRAFFIC CONTROL SYSTEMS
    • G08G1/00—Traffic control systems for road vehicles
    • G08G1/01—Detecting movement of traffic to be counted or controlled
    • G08G1/0104—Measuring and analyzing of parameters relative to traffic conditions
    • G08G1/0137—Measuring and analyzing of parameters relative to traffic conditions for specific applications
    • G08G1/0145—Measuring and analyzing of parameters relative to traffic conditions for specific applications for active traffic flow control
    • G—PHYSICS
    • G08—SIGNALLING
    • G08G—TRAFFIC CONTROL SYSTEMS
    • G08G1/00—Traffic control systems for road vehicles
    • G08G1/07—Controlling traffic signals
    • G—PHYSICS
    • G08—SIGNALLING
    • G08G—TRAFFIC CONTROL SYSTEMS
    • G08G1/00—Traffic control systems for road vehicles
    • G08G1/16—Anti-collision systems
    • G08G1/164—Centralised systems, e.g. external to vehicles

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  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Radar Systems Or Details Thereof (AREA)

Abstract

An above ground on crossing pedestrian detection system 100 comprising: a mono-pulse radar module having at least one transmitter 130 and two receive antennas140, 150, the receive antennas being arranged at spaced locations, in which the radar module is oriented such that a main lobe of a radar signal emitted from the transmitter covers an area which encloses substantially the whole of a must detect zone 170 of a pedestrian crossing, and in which the two receive antennas are oriented such that they receive a portion of the transmitted radar signal that has been reflected from a pedestrian target within the must detect zone, the module further comprising a processing circuit which receives signals output from the two receive antennas, determines the phase difference of the received signals and from the phase difference determines the location of the pedestrian target 190 within the must detect zone. The processing circuitry preferably are configured to reject targets determined to be outside of the must detect zone.

Description

RADAR APPARATUS
This invention relates to radar apparatus and in particular to an above ground on crossing pedestrian detection apparatus.
Pedestrian crossings are well known. A basic crossing comprises a red and green light to control the flow of vehicles through the crossing and another red and green light to tell pedestrians when it is safe for them to cross the crossing. A controller controls the timing of the lights, and a button can be provided which allows a pedestrian to demand that the vehicles are stopped allowing them to cross the crossing.
In many countries there is requirement to detect pedestrians waiting to cross the crossing to improve the flow of vehicles through the crossing. If a lot of pedestrians are detected the traffic may be stopped for longer to allow them to pass. If none are detected the traffic can be allowed to continue and any request to cross can he ignored.
To further enhance the safety of pedestrian when they are on the crossings, it is also known to provide an on crossing pedestrian detection apparatus for detecting pedestrians that are on the crossing. The on-crossing function is used to maintain the all-red period of the lights that stop vehicles passing the crossing whilst pedestrians are on the crossing.
At the time of writing, the requirements for pedestrian crossing are defined in the document TR2506 and for on crossing pedestrian detection apparatus are defined in the document TR2507 published by the Highways Agency, UK. In summary, the apparatus must respond to a minimum size pedestrian in the "must detect" zone including detection of a person in a wheelchair. In addition, it must not respond to a maximum sized pedestrian in the "must not detect" zone.
Various proposals for on crossing pedestrian detection apparatus have been made based on the use of one or more video cameras. Whilst good results have bene obtained in daylight, the requirement to detect in all lighting conditions is particularly challenging for image-based detection.
It has been proposed to use radar to detect pedestrians crossing in the "must detect zone", but designs to date have been difficult to set up because of the mismatch between the shape of the lobes of the transmitter and the must detect zone, making the devices sensitive to accidental misalignment following commissioning.
An object of the present invention is to provide an improved above ground on crossing detection apparatus that ameliorates problems with prior art apparatus.
According to a first aspect the invention provides an above ground on crossing pedestrian detection system comprising: a monopulse radar module having at least one transmitter and two receive antennas, the receive antennas being arranged at spaced locations, in which the radar module is oriented such that a main lobe of a radar signal emitted from the transmitter covers an area which encloses substantially the whole of a must detect zone of a pedestrian crossing, and in which the two receive antennas are oriented such that they receive a portion of the transmitted radar signal that has been reflected from a target within the must detect zone, the module further comprising a processing circuit which receives signals output from the two receive antennas, determines the phase difference of the received signals and from the phase difference determines the location of the target within the must detect zone.
The processing circuit may be arranged to reject targets that are determined to be outside of the must detect zone.
The processing circuit may determine the location as an XY polar coordinate or point for the target and compare with the polar co-ordinates of a boundary of the must detect zone that is stored in a memory accessible to the processing circuit to determine if the target is in the must detect zone.
The processing circuit may be arranged to track the speed of the target from information contained within the two signals output from the two receive antennas, and optionally to track the direction of movement of the target.
The processing circuit may detect the speed and direction of movement of the target using Doppler processing on one or both of the signals output from the two receive antennas. The return signals reflected from a pedestrian in the must detect zone will be frequency shifted in proportion to their speed and the direction of travel can be determined by the frequency shift In one preferred arrangement, the antenna may transmit a signal that ramps in frequency, and the processing circuit may mix this signal with the signal output from each receive antenna to produce a pair of difference signals. Each difference signal may be processed using FFT routines to determine both the frequency and the phase of each of the two signals. The processing circuit may determine the angle of arrival using a known spacing between the two receive antennas and may then apply trigonometry to determine the polar coordinates of the target.
The processing apparatus may track each detected target using a predictive tracking algorithm, and may validate each track against one or more stored parameters. The processing apparatus may validate each track by determining if the target associated with the track is large enough to be above the noise floor of the signals that are being processed, if the target is inside the detection zone, if the target has moved a set distance from the first point at which it was detected and if the target has been seen a minimum number of times. If the target does not meet these tests it will he marked as an invalid track or rejected or disregarded.
Validating the track allows the apparatus to determine if the target is large enough to he a pedestrian or other relevant target such as a cyclist or a horse rider, and ensures that fall tracks from noise in the signal are not acted upon.
The rnonopulse radar module may transmit an FMCW radar signal which is used by the processing apparatus to determine the range of the target, the range being combined with angle information obtained from the reflected signals to determine the coordinates of the position of the target in an XY space that contains the detection zone.
Where there is more than one pedestrian in the must detect zone the processing circuit may be configured to detect the position of each pedestrian that reflects a radar signal back to the two receivers.
The on crossing detection apparatus may include a pair of output ports and the processing circuit may vary the impedance of an electrical path when at least one pedestrian is detected on the crossing. For example, the impedance may he high when a pedestrian is detected and low or zero when no pedestrian is detected.
The apparatus may include a relay that connects the two output ports, the processing circuit opening the relay to generate the high impedance and closing it to generate the low or zero impedance.
The apparatus may include a user operable input.
The apparatus may include a screen and the input may comprise a graphical user input, GUI. The GUI may display a representation of the crossing enabling the user to set the length and width of the must detect zone.
The apparatus may include a housing with a fixing bracket that will permit the radar transmitter to be aligned relative to the must detect zone such that the whole zone falls within the main lobe of the radar.
The housing may house one of the receiver antennas, the processing circuit and the transmitter. It may also house a power supply for the processing circuit and transmitter.
The other receiver may also be located in the housing. Preferably the antennas are spaced apart by around one half of the wavelength of the transmitted signal. In practice this will set the spacing at around 5-6mm for a commonly licenced radar band for pedestrian crossings.
There will now be described by way of example only one embodiment of the present invention with reference to and as illustrated in the accompanying drawings of which: Figure 1 shows an embodiment of an above ground on crossing pedestrian detection apparatus in accordance with an aspect of the invention; Figure 2 shows a regulation layout for a crossing showing both a must detect zone and a must not detect zone; Figure 3 is a schematic system diagram showing the key components of the apparatus of Figure 1; Figure 4 is a bode plot showing the output of the radar antenna; Figure 5 is an illustration showing the trigonometry that enables the polar coordinates to be calculated; and Figure 6 shows in more detail a suitable implementation of the microwave frequency circuit that forms the radar module of Figure 1 and Figure 3.
An above ground on crossing pedestrian detection apparatus in accordance with an aspect of the invention is shown in Figure I and Figure 3. The apparatus 100 comprises a housing 110 and a fixing bracket 111 that enables the housing to be secured to a pole 115 adjacent a crossing at a height above ground of approximately 3m.
The housing 110 houses a power supply 210 that receives an input voltage fed to the pole 115 from a power source (not shown) and, if required steps this down as appropriate to a voltage that is suitable for driving a processing circuit 200. The processing circuit 200 controls the operation of a radar module 120 located in the housing 110 and also processes signals output from the radar module 120.
The radar module 120 is shown in Figure 6 and comprises a local oscillator acting as a source of a microwave frequency signal. This signal is fed into a microwave frequency transmitter 130 secured to the housing 110 and oriented so that radiation emitted from the transmitter is directed towards the crossing. The radar module 120 also comprises two microwave frequency receive antennas 140,150 each offset spatially from the other. These are secured to the housing 110 so they each face the crossing and will receive any reflected radar from a target 190 located on the crossing. Each receive antenna outputs a respective microwave signal.
The transmitter and receiver antennas of the radar module 120 are configured as an Frequency modulated continuous wave (FMCW) Monopulse radar and emit two substantially overlapping main lobes, one vertically polarized and the other horizontally polarized. This is shown in Figure 3. The transmitter 130 is oriented so that the lobes enclose an area including the whole of the must detect zone 170 of the crossing, with the receive antennas 140, 150 oriented so that the will receive reflections from targets 190 that may he anywhere in the must detect zone. As the lobes are not the same shape as the must detect zone, reflections from objects in the must not detect zone may also be received.
The processing circuit 200 receives the two signals output from the receive antennas 140,150 and determines the phase difference of the received signals and from the phase difference determines the polar co-ordinates of a pedestrian target 190 within the must detect zone 170 that produced the reflection. Figure 6 shows the radar module circuit 120 in more detail.
The determination of the polar coordinates is possible because the two receive antennas 140, 150 are offset from each other. Referring to Figure 5 and assuming that the two receivers are separated by a distance d, with a wavefront incident at an angle 0, then the extra path the signal must travel between Antenna 1 and Antenna results in a phase difference between the two antennas that is a function of these variables and the constant known distance d.
Associated with the processing circuit 200 is a memory 240 which stores a user defined set of co-ordinates defining the boundary or the must detect zone 170. The processing circuit 200 determines if the co-ordinates of the target are within the boundary and if they are a signal is output indicating that there is a pedestrian on the crossing. If they fall outside the must detect zone 170 no such signal is output. This is repeated continuously for all targets that are generating reflections.
The apparatus also comprises a relay 220 located within the housing. When the signal is output indicting that a pedestrian is on the crossing the relay 220 is closed to generate a low impedance between two output ports 23,232 that can be accessed from outside of the housing. When no such signal is generated the relay 220 is held open to create a high impedance.

Claims (10)

  1. CLAIMS1. An above ground on crossing pedestrian detection system comprising: a monopulse radar module having at least one transmitter and two receive antennas, the receive antennas being arranged at spaced locations, in which the radar module is oriented such that a main lobe of a radar signal emitted from the transmitter covers an area which encloses substantially the whole of a must detect zone of a pedestrian crossing, and in which the two receive antennas are oriented such that they receive a portion of the transmitted radar signal that has been reflected from a pedestrian target within the must detect zone, the module further comprising a processing circuit which receives signals output from the two receive antennas, determines the phase difference of the received signals and from the phase difference determines the location of the pedestrian target within the must detect zone.
  2. 2. An above ground on crossing pedestrian detection system according to claim 1 in which the processing circuit is arranged to reject targets that are determined to he outside of the must detect zone.
  3. 3. An above ground on crossing pedestrian detection system according to claim 1 or claim 2 in which the processing circuit determines the location point of a target as an XY polar coordinate and compares the point with the polar co-ordinates of a boundary of the must detect zone that is stored in a memory accessible to the processing circuit to determine if the target is in the must detect zone.
  4. 4. An above ground on crossing pedestrian detection system according to any preceding claim in which the processing circuit is arranged to track the speed of the target from information contained within the two signals output from the two receive antennas, and optionally to track the direction of movement of the pedestrian target.
  5. 5. An above ground on crossing pedestrian detection system according to claim 4 in which the processing circuit detects the speed and direction of movement of the pedestrian using Doppler processing on one or both of the signals output from the two receive antennas.
  6. 6. An above ground on crossing pedestrian detection system according to any preceding claim in which the antenna transmits a signal that ramps in frequency, and the processing circuit mixes this signal with the signal output from each receive antenna to produce a pair of difference signals, each difference signal being processed using FFT routines to determine both the frequency and the phase of each of the two signals.
  7. 7. An above ground on crossing pedestrian detection system according to any preceding claim in which the processing apparatus tracks each detected target using a predictive tracking algorithm, and validates each track against one or more stored parameters.
  8. 8. An above ground on crossing pedestrian detection system according to any preceding claim in which the monopulse radar module transmits an FMCW radar signal which is used by the processing apparatus to determine the range of the target, the range being combined with angle information obtained from the reflected signals to determine the coordinates of the position of the target in an XY space that contains the detection zone.
  9. 9. An above ground on crossing pedestrian detection system according to any preceding claim which includes a pair of output ports and the processing circuit varies the impedance of an electrical path when at least one pedestrian target is detected on the crossing.
  10. 10. An above ground on crossing pedestrian detection system according to claim 9 which includes a relay that connects the two output ports, the processing circuit opening the relay to generate a high impedance between the ports and closing it to generate a low or zero impedance between the ports
GB2018131.9A 2019-11-21 2020-11-18 Radar apparatus Pending GB2589984A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GBGB1916994.5A GB201916994D0 (en) 2019-11-21 2019-11-21 Radar apparatus

Publications (2)

Publication Number Publication Date
GB202018131D0 GB202018131D0 (en) 2020-12-30
GB2589984A true GB2589984A (en) 2021-06-16

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GBGB1916994.5A Ceased GB201916994D0 (en) 2019-11-21 2019-11-21 Radar apparatus
GB2018131.9A Pending GB2589984A (en) 2019-11-21 2020-11-18 Radar apparatus

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Application Number Title Priority Date Filing Date
GBGB1916994.5A Ceased GB201916994D0 (en) 2019-11-21 2019-11-21 Radar apparatus

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5815112A (en) * 1995-12-05 1998-09-29 Denso Corporation Planar array antenna and phase-comparison monopulse radar system
US20090267822A1 (en) * 2008-04-28 2009-10-29 Hitachi, Ltd. Mobile radar and planar antenna
US20100201518A1 (en) * 2009-02-12 2010-08-12 Honeywell International Inc Microwave curtain sensor
EP2284568A2 (en) * 2009-08-13 2011-02-16 TK Holdings Inc. Object sensing system

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5815112A (en) * 1995-12-05 1998-09-29 Denso Corporation Planar array antenna and phase-comparison monopulse radar system
US20090267822A1 (en) * 2008-04-28 2009-10-29 Hitachi, Ltd. Mobile radar and planar antenna
US20100201518A1 (en) * 2009-02-12 2010-08-12 Honeywell International Inc Microwave curtain sensor
EP2284568A2 (en) * 2009-08-13 2011-02-16 TK Holdings Inc. Object sensing system

Also Published As

Publication number Publication date
GB201916994D0 (en) 2020-01-08
GB202018131D0 (en) 2020-12-30

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