So I've recently used a PID controller to build a bot for a 2d physics based game. I also did a bit of reading on steering behavior but am still confused over one thing: Is a PID controller considered an implementation of steering behavior? Or are they two completely unrelated things?
I've use the term "steering" to describe PID control.
I find that I often have two parts to control a physics object:
First, a higher level function uses strategy/logic to determine where to steer to.
Next, the lower level function of actually steering towards this point, for which I tend to use PID controllers.
Oh, and as last step, you take the PID output of course, and use it as a force to apply to your physics object. Either as a linear force, or a torque. (If you want to cheat, you could use it to set a velocity, but that makes your simulation discontinuous.)
So to conclude, I think you can say that PID control is a form of steering, yes.