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LDC1614EVM: Inductance Sensing for 3D Rotation Detection: Seeking Advice and Hardware Solutions

Ata Vafi
Prodigy 10 points
Part Number: LDC1614EVM

I am attempting to detect changes in inductance/resonance frequency shift versus 3D rotations (tilt, yaw, and pitch) at a specific distance from the sensor. To be more specific, I am attempting to detect a metal object positioned 5cm away from the sensor that can be rotated. I have purchased the LDC1614EVM, which supports four channels of inductive sensors. I have several questions on this matter and would greatly appreciate any assistance.

  • I am searching for a device that can mount the sensor and the target and digitally control both the distance between them and their 3D rotation. I watched a video on proximity sensing applications at this link: Click This Link: Getting Started with the LDC1000 EVM. Between 5:15 and 5:50 minutes into the video, I observed a sensor mounted on a stepper motor, and the distance between them can be digitally controlled precisely. I am interested in obtaining the sensor/target mount and target showcased in the video to perform similar measurements for my application. To that end, I am looking for more details regarding the availability and specifications of these accessories. Specifically, I would like to know the part numbers or product names for the sensor/target mount and detailed specifications and features of the sensor/target mount, including their dimensions, materials, and any adjustable parameters that facilitate achieving specific axis and rotation measurements.

  • What is the recommended sensor configuration to accomplish my desired objective? Should the sensors be organized in a circular, rectangular, or any other specific pattern?

Thanks

  • 0
    TI__Mastermind 40400 points

    Hello Ata,

    Can you provide some information on the size/shape and material type of the metal object?

  • 0 in reply to Eddie LaCost
    Prodigy 10 points

    Hi Eddie,

    Thank you for your reply. I have constraints on the size, which should not exceed 10x10mm², and the thickness can be up to approximately 1cm. The shape can be any shape, and the material doesn't matter at this stage.

  • 0 in reply to Ata Vafi
    TI__Mastermind 40400 points

    5cm range will not be possible with a 10x10mm target size.  If you are able to work with a range of ~1cm, it could be possible to explore solutions.  Would a shorter range be acceptable in the application?

  • 0 in reply to Eddie LaCost
    Prodigy 10 points

    A shorter range is not possible, but the target can have any kind of form factor. Is there a tool that I can use to input my design requirements, such as sensing distance and sensor resolution? The tool would then output the sensor specifications and the target requirements, including its size. I would like to know what the typical target size is for sensing from that far away. I have found the LDC tool Excel sheet; however, there was nothing related to target design. I am looking for the tool shown in this link: https://e2e.ti.com/blogs_/b/analogwire/posts/inductive-sensing-five-minute-sensor-coil-design. However, the new version of the tool does not have these features shown in the picture.

  • 0 in reply to Ata Vafi
    TI__Mastermind 40400 points

    Ata,

    Take a look at the app notes below on coil design and target design considerations.  Typically, the range that can be achieved is about half the diameter of the coil.  Also note that the max size coil the LDC devices can properly excite is about 50mm.  Generally, the target should be similar sized to the coil.  Section 2.4 of the sensor design app note discusses this.   

    https://www.ti.com/lit/an/snoa930c/snoa930c.pdf 

    https://www.ti.com/lit/an/snoa957b/snoa957b.pdf 

    5cm range is pretty long range for inductive sensing.  If you could have an optimized coil design about 50mm in diameter and similar sized target of good conductive material(aluminum or copper), you may be able to get close to the 5cm range, but if you are just at the edge of the detectable range, this won't give very good dynamic range.  Keep in mind that you would also need to have a coil for each axis and you could potentially have coupling between the coils.  I think it should be possible using inductive sensors, but very challenging.