I initialize my PID controller with specific max and min values:
common::PID posPID;
posPID.Init(0.01, 0.1, 1.0, 1.0, 0.0, 200.0, 0.0);
and when I do
posPID.Update(desiredVel - _spindle.angVel, _stepTime);
the value it returns can be negative or bigger than 200
Any hints what might be the problem?
I ripped this right from the source...
// Check the command limits
if (!ignition::math::equal(this->cmdMax, 0.0) && this->cmd > this->cmdMax)
this->cmd = this->cmdMax;
if (!ignition::math::equal(this->cmdMin, 0.0) && this->cmd < this->cmdMin)
this->cmd = this->cmdMin;
return this->cmd;
Looks to me like you can't have a min of zero. It has to be something other than zero to be a min. This is definitely a bug, and should be addressed. For now, you could just set it to a small number like 0.001 and see if that works.
I can't immediately see why it's not respecting the 200 limit however. How much greater are we talking about? Can you add a smallest-possible-reproducible example?
You should consider making a pull request to allow a minimum of 0! It would a simple first-time contribution. We could require -inf/inf as the values if you want no min or max, and then remove that check for zero.
Asked: 2016-04-23 16:41:53 -0500
Seen: 277 times
Last updated: Apr 26 '16
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