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Global Var

javi pks

HI!!

I declared 3 global var, i call it inside diferent task and every execution this var should be updates but not to do it.
I have a 8051 under evaluation board.
Maybe can be a problem of my small micro?
What do u think about this?

Thanks

Parents
  • 0 in reply to javi pks

    I see some serious problems with your implementation.
    I think your integrator is totally wrong - you do not even accumulate the error!
    it should be something like this:

    double UpdatePID(SPid * pid, double error, double position)
{
  double pTerm, dTerm, iTerm;

  pTerm = pid->pGain * error;

  // calculate the proportional term
  // calculate the integral state with limiting

  pid->iState += error;
  if (pid->iState > pid->iMax) pid->iState = pid->iMax;
  else if (pid->iState < pid->iMin)
  {
     pid->iState = pid->iMin;
     iTerm = pid->iGain * iState;
  }

  dTerm = pid->dGain * (position - pid->dState);
  pid->dState = position;

  return pTerm + iTerm - dTerm;
}

Reply
  • 0 in reply to javi pks

    I see some serious problems with your implementation.
    I think your integrator is totally wrong - you do not even accumulate the error!
    it should be something like this:

    double UpdatePID(SPid * pid, double error, double position)
{
  double pTerm, dTerm, iTerm;

  pTerm = pid->pGain * error;

  // calculate the proportional term
  // calculate the integral state with limiting

  pid->iState += error;
  if (pid->iState > pid->iMax) pid->iState = pid->iMax;
  else if (pid->iState < pid->iMin)
  {
     pid->iState = pid->iMin;
     iTerm = pid->iGain * iState;
  }

  dTerm = pid->dGain * (position - pid->dState);
  pid->dState = position;

  return pTerm + iTerm - dTerm;
}

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