Motion Tracking Using Piezos

    Mar 28 2006 | 10:26 am
    I'm hoping to track where a ping pong ball hits the table during a live game of table tennis.
    I'm intending to use an array of Piezo transducers and calculate the position of impact by calculating the time the signal takes to travel to each mic ie triangulation.
    Does anyone have any experience relating to this. Do you think it would work? Would I need to do some kind of analysis rather than just timing?
    To make matters worse I am totally inexperienced with maxmsp! I have however used pd before as well as several other node based software environments.
    Any links, tutorials, help, anything would be greatly appreciated!

    • Mar 28 2006 | 12:30 pm
      Hi, Gavin.
      It is possible as this project does precisely the tracking you're suggesting:
      best, matthew
    • Mar 28 2006 | 12:59 pm
      Thanks for that.
      That's pretty much exactly the same thing that I wanted to do though. Which begs the question should I bother?
      Always a source of debate in my own head - is it worth creating something that's been done before.
      On the one hand I've never made it before so I'm sure I'd still get alot out of it. Similarly assuming I delivered the project, people would enjoy it.
      On the other maybe I should spend my time creating something which has never been seen before!
      Augmented Air Hockey perhaps!
    • Mar 28 2006 | 2:14 pm
      On 28-Mar-2006, at 14:59, gavin wrote:
      > On the one hand I've never made it before so I'm sure I'd still get > alot out of it.
      At college level (which, IMS, is the context here), doing stuff yourself and getting a lot out of it is (almost always) the most important point.
      When you're writing your PhD or in industry or working as a freelance artist, then originality and uniqueness become increasingly an issue.
      There are exceptions and not-alwayses. Copland wrote a nice article once about Ravel & Debussy *not* being the first orchestral impressionists: there was an obscure composer a generation earlier using very similar techniques. But Ravel & Debussy did it more compellingly.
      Good luck Peter
      -------------- ------------- Peter Castine +--> Litter Power & Litter Bundle for Jitter
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    • Mar 28 2006 | 2:30 pm
      No I'm not a student.
      I have a travelling interactive entertainments show which i take to events.
      If you're interested see
      Originality is kind of important to me but not as important as creating work which enables people to have an experience.
      I have made things in the past which were completely unoriginal (though I only found out afterwards.)
      Saying that I was a student then.
      I still like to learn stuff though!
      I guess really it depends if you add anything of yourself to the concept/project.
      Anyway I've mailed the people who made the original and asked them what they thought!
    • Mar 28 2006 | 2:31 pm
      If you watch the videos, its technically interesting, and fun to watch, but has a lack of artistic content. There is your chance to make it better. There must be more than proof of concept, this stuff could need an artistic expression which stands out as a work of art on its own.
      Go for it, as long it makes sense for you...
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    • Mar 28 2006 | 3:21 pm
      Thanks for the feedback.
      Seeing as I am an MSP newbie I'm gonna go with it for a while and see what happens.
      I have set up this initial test:
      Two microphones. If the volume on either rises above a certain amount, I trigger a bang and start the timer object.
      When the other mic rises above the threshold I trigger the other side of the timer.
      Thing is the timer always reads 0. Well sometimes it reads 100.
      So I guess I need to learn some basic theory about sound.
      The frequency is 44100 times a second. Does the computer receive 44,100 messages every second?
      It doesn't does it. Presumably there is some kind of resolution.
      And how is this related to the setting of audio buffers?
    • Mar 29 2006 | 10:56 am
      Thanks Vincent.
      I feel slightly embarassed about posting my patch which is really only an example patch changed a tiny bit but here goes.....
      As far as I can tell a knock which reaches one microphone first should trigger the time difference when it reaches the other mic.
      The signals appear to be occurring at the same time and I seem to be getting data into max only 10 times a second.
      I know I am missing some simple piece of knowledge!
    • Mar 29 2006 | 11:26 am
      > The signals appear to be occurring at the same time and I seem to be > getting data into max only 10 times a second.
      Have a look in meter~ inspector : by default, interval is set to 100 ms. Maybe you should use peakamp~ instead of meter~ to be sure to miss nothing...
      MathieU Chamagne
    • Mar 29 2006 | 12:41 pm
      Thanks for your help. I never knew about the inspector. You're right anyway using the meter is kind of pointless. I'll have a look at peak meter
    • Nov 22 2012 | 11:57 pm
      How did that went? any news how to get good coordinates in the table?