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LDC1101: Non-parallelism between PCB inductor coil and target

Alex Moreland
Prodigy 80 points
Part Number: LDC1101


Does anyone have any information regarding the effect of non-parallelism on the inductance measurement of the LDC1101? I have a target that displaces axially in front of the PCB inductor coil. This target is also able to tilt relative to the axis of translation. Is there a way to quantify the effect of this tilt angle on the sensor measurement? I'd appreciate any information.

Best regards

Alex M.

  • 0
    TI__Mastermind 23810 points

    Alex,

    Tilting of the target will impact the measurement. To quantify, you would need to collect test data. Note that a tilt will likely be indistinguishable from a change in distance of the target from the sensor.

    There might be a way to use multiple sensors to help compensate for this problem, but I cannot comment more without understanding what you are trying to do mechanically.

  • 0 in reply to Clancy Soehren
    Prodigy 80 points

    We're using the sensor coil to measure the position of an expanding and retracting bellows with an aluminum cap. Because the bellows is flexible there is a chance that it can tilt.

  • 0 in reply to Alex Moreland
    TI__Mastermind 23810 points

    Thanks for the drawing. You could try using two side-by-side coils to help with this issue. That way, when you see a difference between the coils, you will know that there is a tilt.

    Unfortunately, this has a major drawback. The distance detection and resolution is always improved when a larger coil is used. By cutting the coil area in half, the maximum distance that the coils can detect will also be cut in half.

    Without using a second coil, you will find that a tilt looks identical to a small shift in the x direction. The success of the design will then depend on the tolerances that you are aiming for and the degree of tilt that is possible.

  • 0 in reply to Clancy Soehren
    Prodigy 80 points

    Sounds good. We'll just have to quantify then the effect of tilt on our measurement then and specify a tolerance on the maximum amount of tilt allowed. Thank you for your help. I appreciate it!


    Best regards,

    Alex M.