I realize this question is not directly related to signal processing, however, it's relevant to system analysis which is relevant to most signal processing engineers. There's also no good alternative stack exchange for me to post this question to (please let me know if there is though).
I'm currently struggling to tune an air-bearing actuator. Because this actuator has such low friction, most of the energy put into it will not dampen itself out naturally. Instead, I'm relying on the derivative gain of my PID controller to do that.
However, I'm struggling to achieve a stiff system (high proportional gain) without it going unstable. I'm using a high powered amp with this stage which is plenty capable of creating stiff control, however, when ever I increase the proportional gain the stage goes unstable. My hope was that I could increase the derivative gain in response to this, yet even doing this it doesn't seem to make the system stable.
What I'm running into is a system that is "squishy" controlled that then goes unstable when I try to increase the proportional gain.
What exactly am I doing wrong?