Idea: hanging 2DOF seat

I've seen several 2DOF designs here in the forum, recently. When it comes to optimized cost you can't beat the 2DOF approach. The U-joint, usually in the center under the seat, supports all of the weight so the motors don't need much power.

I've never tried out one myself. But from the theoretical point of view there's something I find somewhat disturbing. With the center of rotation under the seat every roll movement also generates a sway impulse and every pitch a surge. Unfortunatelly, sway and surge goes in the opposite direction as you'd normally need.

Example: First, lets assume an unlimited 6DOF simulator. When you accelerate this requires a surge forward cue. If the acceleration takes longer the surge has to be followed by a pitch up so that the pilot is pushed back into the seat. But with a 2DOF seat with bottom U-joint both cues are mutually exclusive. Pitch up generates a surge backward which should, in my point of view, give a false cue of braking instead of accelerating for a short moment.

So how about moving the pivot point above the seat?

Has anybody tried or at least considered this? Is the false surge/sway cue noticable? It can't be too bad, otherwise the 2DOF with U-joint under the seat wouldn't be so sucessful and wide-spread.

Ah yes, I forgot about that. If you pitch forward the fixed pedals put force on your feet which feels like a surge backward with the pedals coming closer.