Yes good info there. Good to have the "vibration on upshift" clarified. It seems its a torsional vibration issue excited by unusual combustion pressure signatures. It was only occurring on upshift where engine revs drop significantly in a few milliseconds thanks to seamless shifting.
My interpretation is that turboshaft inertia and/or response time of the DBW throttles results in an inappropriate intake manifold pressure for a short time after the shift. I am surprised they weren't able to cure this by either:
- anticipating the shift and commencing movement of the DBW throttles to the ideal post-shift position - before the shift actually happens. (Driver commands upshift, throttles start moving, upshift occurs . . )
- controlling one of the faster response parameters (ignition timing, injection duration or injection timing) to avoid the vibration.