So basically I'm trying to figure out the distance that a person's hand is from maybe a point on the center of their chest and their bicep. I'm trying to get the position they are moving in as they attempt an exercise. I've tried using accelerometer and gyros but there error is horrible and adding a magnetic sensor and then using Kalman filtering to predict the positioning is probably out of my skill level. So I'm thinking to place magnets on the bicep, wrist and center of the chest and somehow measuring the distance between them with a magnetometer as the person is moving their arm. Is this possible? If not, are there any other options I can try.

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    \$\begingroup\$ Strength of a magnetic field over distance aside (I'm sure you've held a magnet to a fridge before and see how quickly it becomes ineffective as you move it away) Why do you think trying to figure out position with a magnetic field is any simpler? \$\endgroup\$
    – DKNguyen
    Jan 3, 2020 at 20:49
  • \$\begingroup\$ Even if you use rare earth magnets? I don't need exact positioning, I could even work with displacement from each other. \$\endgroup\$
    – Nik B
    Jan 3, 2020 at 21:00
  • \$\begingroup\$ Hold a rare earth magnet up to a fridge. I mean, we have compasses that work with things as weak as the Earth's magnet field, but I don't think it's going to work the way you want it to work. \$\endgroup\$
    – DKNguyen
    Jan 3, 2020 at 21:02
  • \$\begingroup\$ I see. That's rather unfortunate. Thank you though! \$\endgroup\$
    – Nik B
    Jan 3, 2020 at 21:05
  • \$\begingroup\$ If magnetic field sensing has any hope of working, you'd likely need AC-field generators/sensors. And an environment free of magnetic-sensitive iron-type stuff. \$\endgroup\$
    – glen_geek
    Jan 3, 2020 at 21:06

1 Answer 1


I think capacitive proximity sensors can be made to work here.

Maybe take a look at Theremin operating principle.


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