Connect with us

Sensor ideas

Discussion in 'Sensors and Actuators' started by MartinV279, Oct 28, 2014.

Scroll to continue with content
  1. MartinV279

    MartinV279

    14
    1
    Aug 19, 2014
    I'm making a sensor glove and need sensors to measure finger flexing. Tried to make some sensors with piezoresistiive materials such as Velostat and ESD bags, but the output is too unstable. Any witty ideas for an alternative sensor that can measure that?
     
  2. Arouse1973

    Arouse1973 Adam

    5,164
    1,080
    Dec 18, 2013
    What about sensing the tendons in the wrist with a Bimorph sensor or piezo disc?
    Thanks
    Adam
     
  3. Arouse1973

    Arouse1973 Adam

    5,164
    1,080
    Dec 18, 2013
    hevans1944 likes this.
  4. MartinV279

    MartinV279

    14
    1
    Aug 19, 2014
    This tendon sensing idea sounds really cool. I just can't wrap my mind around sensing the tendon contractions by a bimorph piezoelectric sensor.

    Using accelerometer as sensor for each joint is actually not a bad idea at all. They sometimes do make even a better gyro than a gyro.
     
  5. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    Difficult to accurately detect without some additional math though if the object they are mounted to is in angular motion or accelerating in any given direction. You are also limited to relying on gravity to determine the current angle making horizontal gestures difficult to detect and track.
     
  6. MartinV279

    MartinV279

    14
    1
    Aug 19, 2014
    Absolutely true. But not too long ago I got a MPU6050 aliexpress clone and needed to rely on the acc more than the gyro, because the later was very much not-in-good-health. If the motions are predetermined, and no further global movement on the referent frame is applied, I think that can be done. For example, in this case of finger sensing, if the hand is flat parallel to the ground there won't be any problem. After all, a MEMS gyro won't hurt anyone.
     
  7. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    Good call. You can also use flex, strain, or stretch sensors.
    http://www.adafruit.com/product/519
    This is a bad example... as I think it's overpriced, but the technology is there.
     
    hevans1944 likes this.
  8. MartinV279

    MartinV279

    14
    1
    Aug 19, 2014
    I understand what you mean. I tried making flex sensors, but didn't end very well (as I mentioned in the opening comment). Don't know about strain gauge/sensor, but stretch looks so helpful at this point. Too bad I live in Macedonia and ordering something like this (if it's even possible to be shipped) will become 40% more expensive at least.
     
  9. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    Ahh. I get why you tried to make your own now ;)
    Keep your eyes open.

    What kind of gestures do you want to detect?
    You could detect a finger open or closed, or you could detect any number of increments as the finger moves.
    The type of accuracy you want will help narrow down your options.
     
  10. hevans1944

    hevans1944 Hop - AC8NS

    4,455
    2,073
    Jun 21, 2012
    I think a sensor-glove woven with stretch-fibers that change resistance or perhaps optical characteristics (think fiber optics) could be made inexpensively. But a team of Ukranian students has built something that isn't too shabby... check it out.
     
  11. MartinV279

    MartinV279

    14
    1
    Aug 19, 2014
    I need about 4 solid regions. Fully closed, fully open, below half and above half. So from the entire range of the closing/opening of the finger I need to get these 4 regions. So the accuracy doesn't need to be that good to detect presence in a particular region. I'm actually trying to make something like those Ukranian students did, but with some extra additions. They used those flex sensors that can be bought on Sparkfun. Stretch and strain sensors are a good option but kind of expensive for a project like this (I think). I should look into these fiber optic based sensors hevans1944 mentioned.
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-