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IWR6843ISK: Ghost object in Long Range People Detection demo

JINHYEONG LEE
Intellectual 740 points
Part Number: IWR6843ISK


Hi, 

I tested Long Range People Detection demo in Industrial Toolbox 4.6.0 with IWR6843ISK.

 

In an open field(without obstacles), IWR6843ISK was installed at a height of 1.5m to face the front, and the detection performance was checked by moving it in various directions.

(In the physical setup of the user guide, it says to tilt it down 2~3 degrees, but to check the maximum distance sensing performance, it was installed in the front.)

So, I changed sensorPosition Config params to "sensorPosition 1.5 0 0".

Below is chirp config I run. (It is modify only "sensorPosition" from "people_detection_and_tracking_50m_2D.cfg" file)

sensorStop
flushCfg
dfeDataOutputMode 1
channelCfg 15 7 0
adcCfg 2 1
adcbufCfg -1 0 1 1 1
profileCfg 0 60 35 6 43.0 0 0 8.241 1 125 3433 0 0 48
chirpCfg 0 0 0 0 0 0 0 1
chirpCfg 1 1 0 0 0 0 0 4
frameCfg 0 1 128 0 100 1 0
lowPower 0 0
guiMonitor -1 1 0 0 0 0 0
cfarCfg -1 0 2 8 4 3 0 10 0
cfarCfg -1 1 0 4 2 3 1 10 0
multiObjBeamForming -1 1 0.5
clutterRemoval -1 1
calibDcRangeSig -1 0 -5 8 256
extendedMaxVelocity -1 0
bpmCfg -1 0 0 1
lvdsStreamCfg -1 0 0 0
compRangeBiasAndRxChanPhase 0.0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0
measureRangeBiasAndRxChanPhase 0 1.5 0.2
CQRxSatMonitor 0 3 4 63 0
CQSigImgMonitor 0 127 4
analogMonitor 0 0
aoaFovCfg -1 -90 90 -90 90
cfarFovCfg -1 0 0 59.99
cfarFovCfg -1 1 -30 30.00
%SceneryParam -50 50 0.5 60 -6 6
staticBoundaryBox -9.5 9.5 0.6 50 0 2
boundaryBox -50 50 0.5 60 -6 6
gatingParam 4 6 6 6 10
stateParam 4 10 60 100 20 600
allocationParam 30 30 0.5 3 2 2
maxAcceleration 0.1 0.1 0.1
trackingCfg 1 2 250 20 78 121 99
sensorPosition 1.5 0 0
presenceBoundaryBox -3 3 2 6 0.5 2.5
sensorStart

 

As a result of the test, several types of ghost objects were observed.

Case1. Observed from the left side of the real object.

 

Case2. Observe from the opposite angle at the maximum detectable azimuth

 

Can I get some advice on what causes ghost objects and how to remove them?

Thanks.

  • 0
    TI__Mastermind 37805 points

    Hi,

    When you say "ghost" objects, I understand this to mean multi-path reflections. Just to make sure we're talking about the same thing here, can you confirm that when your actual target moves, the ghost target moves too, like a mirror image? 

    If that is the case, then I would suggest capturing data using the GUI, and examining the points you receive. I would expect the ghost points to be of reduced SNR because they have to travel further and reflect off multiple surfaces, so increasing the CFAR thresholds should help reduce the number of ghost points that appear. This parameter is the second to last number in the following lines (10 for each). Perhaps try increasing their value.

    cfarCfg -1 0 2 8 4 3 0 10 0
    cfarCfg -1 1 0 4 2 3 1 10 0

    Additionally, you could increase the thresholds required to turn a cluster of points into a track. These parameters (as well as many others) are defined in the 3D people counting tracker layer guide. AllocationParams are a good place to start.

    https://dev.ti.com/tirex/explore/node?node=AHZY4H1u04B21l9zTRElvQ__VLyFKFf__LATEST

    Best,

    Nate

  • 0 in reply to Nathan Block
    Intellectual 740 points

    Thank you for reply,

    I'll try adjust the CFAR threshold and AllocationParams.

     

    By the way, I tested it in an open area to reduce multipath reflections (Ghosts).

    Below is my test environment

    (The distance between the IWR6843ISK and the metal pole was about 1 m)

    Could multipath reflections are caused by a horizontally positioned metal pole or ground?

  • +1 in reply to JINHYEONG LEE
    TI__Mastermind 37805 points

    It's certainly possible, but I cannot really confirm or deny it. If you could test in an environment without the poles present that would likely be able to confirm/deny it.