Like the one on a "Tupperwolf"?
The bit sticking out of the middle of the beanie? OADS.
Another view
Apparently the VIMI?? system in the Tiger uses swashplate displacement/VTG and computes it from that. Only works adequately with a type with low C of G range though.
Then again a pilot with some semblance of situational awareness and experience could probably tell you the same thing from control displacement and close enough to a visual reference and achieve a similar result. As quoted it would be a bit hard in the dark!!