Huh.. I thought about a smoother but I personally didnt think it was necessary. Once the drift goes away and you recenter the position it works very well. All the code will be open sourced once I post it so feel free to mess with it.
No worries, I always have used the raw sensor data coming out of the IMU, but perhaps you are using the internal DLFP or whatever it's called? In my work we have our own 15-state kalman filter that estimates orientation that is augmented by gps so it converges to true heading (without needing a magnetometer.) But we are navigating a UAV ... for a head tracker that would be total overkill and our system actually needs the aircraft movement to converge (your head will be relatively stationary.) I'm just tossing out ideas in case they are helpful.
Also the reason I'm using a 5v regulator instead of a buck converter is due to the coils. I didnt want anything to interfere with the gyros or the video signal. I'm also not that experienced with this stuff so I didn't know how much it would interfere so I just went the regulator route. Again Im no expert so if you think a buck converter wouldnt mess with the gyros at that distance then give it a go. I dont really know what the devices mah ussage is so the step down from 7.4 to 5 didnt seem like inefficiency would be a big deal.
I'm confident the buck converter won't interfere with the IMU, but I have no idea if/how it would affect video. I think if you are happy with your current solution and it's solid, then it's great. In a past project I used a castle creations BEC (both the 10amp little one and the 20 amp dual output with heat sync.) It was always a chore to dial up the output voltage so under load I would get about 5v. When I switched to the traco power regulator it was nice to have a rock solid exact 5.00 volts no matter what I plugged in. But we were attaching more things including GPS, 800mhz linux computer, 100mw radio modem, and possibly servos ... so I'm sure our load was substantially more than yours.
Mostly it's fun to see people mix in some arduino bits into their hobby projects, so I enjoy jumping in with my tiny slice of experience.
My latest tech-crush is micropython (or circuit python). I've started to push in the direction of a 100% python UAV autopilot. I'm not sure I'll get there exactly. It will probably have major subcomponents still written in C++ (with python wrappers) but I'm maybe 50% of the way there with my currently working system (a hybrid of C++ and python and linux and arduino-- err teensyduino ), so time will tell. It seems like most of the UAV DIY'ers evaporated into other interests, but I made the mistake of drinking the coolaid, and now I also do this stuff for my day job at a university.)
Curt.