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AWR1642BOOST: How to trans the Doppler result to the absolute velocity?

Silkworm
Intellectual 815 points
Part Number: AWR1642BOOST

Hi sir,

I know the way to  calculate the result of Doppler in USRR function (we use the TI DEP-0092 package) is " Doppler = (Vx*x + Vy*y) / R ".

But it means the change of range not the absolute velocity of target.

if the target not only moving on the y-axis.

How should I trans the Doppler result to the absolute velocity? (Even though I rotate the placement of RADAR.)

How to get the Vx,Vy from USRR function? or how to get the absolute velocity of target car?

Is any equation to follow?

BR

Thanks

  • 0
    TI__Guru*** 148514 points
    Hi,

    How do you define absolute velocity?

    Thank you
    cesar
  • 0
    TI__Mastermind 21295 points
    Hi Silkworm,

    1. Could you clarify which doc the equation you listed is from?

    2. When you mention "y-axis", is that the axis going straight away from the antenna (same as range when the object is directly in front of the antenna)?

    3. When you say "absolute velocity", are you talking about the velocity in the X-Y plane (i.e. velocity in the direction that the object is moving)?

    Regards,
    John
  • 0 in reply to JohnH
    Intellectual 815 points

    Hi John,

    1. Could you clarify which doc the equation you listed is from?

    In the file "Extended_Kalman_Filter_xyz.c"  >>>  rrd[iRANGE_RATE]


    2. When you mention "y-axis", is that the axis going straight away from the antenna (same as range when the object is directly in front of the antenna)?

    In the practical use is not, I think the target car is not only move on the y-axis straightly.

    Show as the figure the RADAR has an installation angle and the target car is move on the lane.



    3. When you say "absolute velocity", are you talking about the velocity in the X-Y plane (i.e. velocity in the direction that the object is moving)?

    Yes I want to know the velocity in the direction that the object is moving. How to calculate it?

    BR

    Thanks

  • 0
    TI__Expert 4720 points

    Hi

    The velocity information that we can get from a radar signal is the radial velocity of the target.

    To get the Vx, Vy (which includes the tangential component of velocity), you need to track the target  using an appropriate tracker (say, a kalman filter, with an appropriate target model). Over the course of a few iterations, the kalman filter will generate an estimate of the Vx, and Vy. In the SRR demo, it was decided that only the long range targets (i.e. those corresponding to the 'SRR 80m chirp configuration') needed to be tracked. Hence we only track these long range targets, and consequently only generate Vx and Vy for the SRR targets.

    In summary, there is no easy equation to generate Vx, Vy from a radial velocity. You need to track the USRR targets to estimate their Vx and Vy, which is not something we've tested.

    Regards

    Anil

  • 0 in reply to Anil Mani
    Intellectual 815 points

    I got it.

    Thanks for your great support.

    BR