I am wondering if there is a way to measure distance between two movable points (e.g., the first point is on the hand and the second point is on the back of the human body).

I was looking at different types of technologies. I found ultrasonic sensors but those need a reflective object and this does not work with my idea. I thought about separating the transmitter and the receiver but there is the human body (hip) between those points and it can not be face to face. I considered technology based on magnetic fields so it can be measured regardless of obstacles or motion but I did not find anything close to what I want. And for infrared it needs to detect some object.

Is there any technology that can help me achieve this type of requirement?

  • 2
    \$\begingroup\$ Tape measures still work but although you haven't mentioned it I suspect you want it automated and regular without a 3rd party being involved. It's all about clearly defining what you want!! \$\endgroup\$
    – Andy aka
    Commented Jul 30, 2013 at 9:28
  • 2
    \$\begingroup\$ What came to my mind were 1. calipers. 2. motion capture suit. :-) \$\endgroup\$ Commented Jul 30, 2013 at 9:37
  • \$\begingroup\$ @RedGrittyBrick: Motion capture suits are neat. Wonder why they aren't part of the video-gaming scene yet. A bit bulky but surely it can be made more elegant with some R&D. \$\endgroup\$
    – boardbite
    Commented Jul 30, 2013 at 10:50
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    \$\begingroup\$ Linearly "sloped" magnetic field with coil pickups. Up to 3 coils at 90 degrees if rotation involved. This method is used in body motion telemetering systems for movies et al. Less secrecy of application will help answer quality. \$\endgroup\$
    – Russell McMahon
    Commented Jul 30, 2013 at 11:07
  • \$\begingroup\$ @boardbite - The thing is, motion capture suits aren't just a suit, it's a suit, a BUNCH of cameras shooting from every angle, a backdrop that makes using CV techniques to extract the position of the nodes on the suit easier, and a whole bunch of software to glue it all together. It's not really something you could package up easily. \$\endgroup\$ Commented Jul 30, 2013 at 11:09

1 Answer 1


You haven't suggested that the sensor should not physically interact with the body being measured, so given that I'm going to suggest a spool of line (automatically retracting) and a rotary encoder. You might need two spools to allow trigonometry to calculate the actual distance to the hand.


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