I am working on a PID Control software simulator for teaching PID Control concepts interactively.
I am working on an example for a Velocity controller. I have the example working, but I really want the input to my process to be in percentage instead of the output I am getting which is a fixed value that the process should increase by.
Right now I have to interpolate the output increase by the max acceleration for a sample step and then scale the output to a percentage. The problem is that the rate of acceleration is non-linear depending on the speed and current gearing of the drive train.
This works but isn't very flexible or adaptable, for instance, it makes everything accelerate at maximum until it gets near the setpoint velocity and then either overshoots and oscillates a few periods or takes an equally long time to get that last little bit without over shooting.
Sometimes you will want this maximum acceleration behavior, sometimes you will want to manage the battery/fuel source and accelerate at maximum efficiency; sometimes you want a bit of both.
Scaling the output like I am doing now is brute force and not very subtle. I would rather inject a output modifier into the calculation of the output by dynamically tuning the P, I and D gains, but I am not sure which ones to focus on and in what order?
When I tune them manually one at a time I can get really good results, but when I try and start automatically tuning them everything goes crazy.
I have spent the last week reading about control theory and auto tuning and the math notation just gets to cryptic for me, I understand the math if I can find some implementation in code; regardless of language.
I have tried applying Z-N heuristics, but I still get wild swings and it is really hard to compensate for overshoot; is hard to tolerate much overshoot when you can only decelerate at a fraction of the rate you can accelerate. imagine a system with no active braking and only relying on passive drag to slow down
