0.21.1 ASAS too weak.

[triffid_hunter]

I find that the new SAS is a little stronger, but equally as stupid as the old ASAS. The I term in the PID is too high and the D term too low; so my ships keep oscillating back and forth over the actual target heading for ages. I still get wild unbounded oscillations with smaller ships too :/

It's not just watching the ships that tells me this and is certainly not a case of insufficient struts with the control pod flapping around - the axis indicators will still be sitting several ticks on the wrong side of zero while the heading merrily swings straight past the target on the navball, and slide across after the fact just in time for the next part of the oscillation.

Is there any clear reason that a momentum/impulse model wouldn't work better than PID? I know about PID, it must be specifically tuned for the load otherwise poor performance is inevitable, and I haven't noticed anywhere in KSP to re-tune SAS PID for a craft in various stages of launch... At least with momentum/impulse we can go "we have 30 whatsits of rotational momentum, if we shed them at 8 per second then we should reach zero just as our heading hits the target" - exactly the same math as stopping distance for cars.

Also, PID is for systems where the sensed value lags behind the actual instantaneous value.. Surely we know the craft's rotational rate precisely and instantaneously on a frame by frame basis? Or at least can work it out by summing all the individual parts to get an overall value for the ship, like weight or orbital velocity?