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BOOSTXL-PGA460: Ultrasonic beam manipulation for blind zones

Glenn Dukel
Prodigy 30 points
Part Number: BOOSTXL-PGA460
Other Parts Discussed in Thread: PGA460

Dear TI,

For my ultrasonic application it is required that I filter out all readings that are 5 cm from the ground. this is in order to make AGV drive without stopping for small objects, for which another mechanism is used. how do i create a blind zone in which no objects are seen. in the past we used a pepperl fuchs sensor which was able to manipulate the beam characteristics. is it possible to do this with the PGA460 or do I need a special transducer.

I've done some testing with EVM and i cannot differentiate between the objects when they have the same amplitude. also my sensor height is fixed so I cannot simply place it higher.

Kind regards,

Glenn

  • 0
    TI__Mastermind 27940 points
    Hi Glenn,

    Companies such as Pepperl+Fuchs have the advantage of offering Sound Beam Modification since they can optimize the driver/receiver circuitry for their proprietary transducers. Because TI is a semiconductor company only offering the driver/receiver circuitry, we don't have details on how an externally supplied transducer's beam pattern changes across frequency or other driver parameters.

    A modification that is universally applicable to all transducer is a mechanical modification called a horn or wave-guide. By effectively increasing the diameter of the transducer, the beam is focused in the forward facing direction. This modification is described in more detail on FAQ #4.4.9 at: www.ti.com/.../slaa733.pdf

    I do know that the driver frequency can impact the beam pattern, but most transducer manufacturer's only provide the beam pattern details for a single/center-frequency. You would need to characterize the behavior of the transducer across frequency using an external free field microphone to determine how the beam profile's side-lobe dB strength changes. I also recommend that you reach out to the transducer manufacturer to find out if they already have this information available.
  • 0
    TI__Genius 17440 points

    Hi Glenn,

    It is not possible to electronically manipulate beam characteristics with the PGA460. However, there are multiple ways to physically manipulate the beam characteristics that should work for your solution. We've seen success in similar applications using transducers with a narrow vertical field-of-view (FOV) and a wide horizontal FOV. This will also help mitigate any ground-bounce effects. What is your maximum range? This will affect how narrow your vertical FOV should be. A list of transducers with FOV information can be found here.

    If choosing a transducer with a narrow vertical FOV doesn't eliminate the detection of objects 5cm from the ground, you could also try using a horn to direct the beam. 

    Regards,