rate of change question


    Apr 15 2007 | 7:49 pm
    i am using photocells hooked up to the analogue input of a game controller which is being recognized as an hi device. i am trying to figure out a way to record when the amount of light being picked up is changing faster or slower, as in when the output of hi is changing faster i want i higher value, and a lower value when the output is changing more slowly. Basically i need a good way to track the rate of change of a signal. I have tried using the counter object and reseting at set intervals. I have also tried using the count function of the capture object. Neither of these have worked well enough. Any suggestions?

    • Apr 15 2007 | 8:25 pm
      you could use a way of calculating a mean value over a certain amount
      of time (read number of values) and compare this to the new incoming
      values
      Of course this can only be achieved when doing a little bit slower
      then realtime
      I'm also pretty sure that pmpd would be a great way to look at it,
      reading in basicly acceleration or decelaration.
      If you would share the whole concept of the projec I would be more
      then happy to help you out
      best
      pieter
      On 15 Apr 2007, at 21:49, glong wrote:
      >
      > i am using photocells hooked up to the analogue input of a game
      > controller which is being recognized as an hi device. i am trying
      > to figure out a way to record when the amount of light being picked
      > up is changing faster or slower, as in when the output of hi is
      > changing faster i want i higher value, and a lower value when the
      > output is changing more slowly. Basically i need a good way to
      > track the rate of change of a signal. I have tried using the
      > counter object and reseting at set intervals. I have also tried
      > using the count function of the capture object. Neither of these
      > have worked well enough. Any suggestions?
      >
    • Apr 15 2007 | 9:23 pm
      Do you mean signal, as in msp signal? I'm guessing you don't - if so,
      there's an object called tl.velocity by Trond Lossius that should do
      what you want.
      Alternatively, you could roll your own on the basis that rate of change
      is (change in x) / (change in y) - in this case the difference between
      two successive sensor readings divided by the amount of time between
      them (which you can find out using the timer object).
      --
      Owen
      glong wrote:
      > Basically i need a good way to track the rate
      > of change of a signal. I have tried using the counter object and
      > reseting at set intervals. I have also tried using the count function
      > of the capture object. Neither of these have worked well enough. Any
      > suggestions? _______________________________________________ maxmsp
      >