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IWR6843ISK: Sensor angled toward ground on a moving base

Bill Li
Prodigy 20 points
Part Number: IWR6843ISK
We are intending to use the radar to create a "safety bubble" in front of a mobile robot. Because of physical constraints, the sensor must be mounted 0.6m above ground level. Due to the +/- 15deg elevation point detection range of the sensor, if the sensor is mounted upright, then there will be a roughly 0.6m x 2m slice of area beneath the sensor that will not register any detections. To try to reduce this blind spot, we are considering angling the sensor towards the ground (about 30 deg below horizontal) which would reduce the blind distances from ~2m away from the base of the robot to less than 1m. Worth noting: The sensor is configured to have the best velocity resolution at 0.06m/s with the tradeoff of range resolution being at 0.214m.
  1. Is this a reasonable use-case for the sensor, or would we expect to see significant noise when moving over the ground?
  2. With the sensor aimed down, objects will no longer be moving directly towards or away from the sensor (there will be a lateral velocity component). Would this significantly impact velocity measurements?
  3. Should the range/velocity resolution be tweaked to better accommodate this use-case?
  • 0
    TI__Mastermind 23177 points

    Hello,

    This is a reasonable one sensor use case, but there are a few things that you will need to think about and tune appropriately via the cfg file. One is that with the sensor tilt, as you said all the velocities will have a lateral component. The velocity of points will all be relative to the sensor, so what this means if you have the sensor at a 30 degree angle, you will have to do one more calculation in order to get the true x, y, or z velocity of the object. The accuracy of this measurement however will be just as accurate as if it was facing the object straight on, it will just need multiplication to get the vector components. Another for example is what is the expected floor surface? The reflectivity will differ from grass to wood to tile to concrete and you will need to do your own data collection to see what fits your use case best as there is no one size fits all tuning. For some pointers, you can adjust the TX backoff power and CFAR thresholds to tune out noise that is seen from being point towards the ground. I am not sure if you have been using it, but feel free to checkout our mmWave Sensing Estimator and going to the Chirp Design and Tuning tab for quick tuning of core parameters.

    https://dev.ti.com/gallery/view/mmwave/mmWaveSensingEstimator/ver/2.0.0/

    Best Regards,

    Pedrhom Nafisi