Yaw Head Tracking

For those who don’t want to read all of this, flying with yaw head tracking works and is flyable.

I have flown a dual-axis gimbal (pitch and roll) head tracking setup, but until recently had not tried using yaw head tracking. There are a few reasons for that I’ll get into later but considering the head tracker is three axis and all it takes is adding a mix in for the existing yaw channel, I am surprised I hadn’t tried it until now.

I met a lot of great pilots at Rampage 2022 including Jamie a.k.a. Little Steller Fox, we met up to fly recently and I got her to try flying with one of my head tracking FPV gimbal setups. Not only did she fly it without crashing or getting disoriented, but she was already starting to use the gimbal dynamically in the first flight, same for the pros that flew it at Rampage, I should’ve gotten DVR of all of them. It’s awesome seeing people fly with it, I’m very grateful for the opportunity to introduce people to it, more than once I have heard people say it’s “kind of freeing”, I can’t agree more with that statement.

After flying it, she mentioned that it felt like yaw head tracking would be nice, and that some of the people from Rampage had mentioned that as well. I explained that the reason I hadn’t tried it was because you can already yaw a multirotor freely without affecting flight path, essentially a normal FPV drone is a flying yaw gimbal, you can spin a force vector all you want. I also mentioned that admittedly, particularly when in flow state, I turn my head when flying despite having good discipline for head position in relation to pitch. Usually when I turn my head, I am just naturally trying to track something the same way I do with the gimbal/pitch.

Side note, I had thought that having yaw controlled via normal head tracking, where the channel value is an offset from a center point (i.e. based on position), may be very hard to control and feel unnatural, because if you keep your head turned the drone will continue to yaw until you come back to center. I had thought about the possibility having the channel value based on angular velocity instead, so that as you moved your head it would yaw but then as your head came to a stop the drone stopped yawing. I may look into if there’s a way to use an OpenTx Function to convert position to velocity, if that’s not possible I may talk to Cliff (open source head tracker project creator) about how difficult this would be to implement that in the head tracker itself. But that’s for another day.

I explained that to Jamie and she said that she thought normal head tracking with yaw wouldn’t be hard to control, and that it may work better than the angular velocity idea. I responded saying that normal head tracking with yaw should be extremely easy to try, and that we could even try it right then if we wanted to, she asked “why not?”.

Another side note. I love moments like this, exploring unknowns is exactly what started this whole project.

I started setting up my transmitter to mix yaw into the existing yaw channel, setting the ‘weight’ of the head tracking mix low (20%) to give the best chance of not crashing, I recommend the same thing for learning to fly with the gimbal. I asked Jamie if she wanted to do the honors and try it first and she declined saying I would have the best chance given that I had already been flying with head tracking for pitch.

I took off and was pleasantly surprised to find that it wasn’t hard to control and felt pretty natural as well. It wasn’t allowing me to do anything I couldn’t normally, but it was working, and it was fun, and I could see how someone might want to use it as the primary yaw control with the stick acting as a backup control, allowing throttle to have it’s own stick. You could also use the stick for yaw like normal but still have the head tracking active so that when you turn your head instinctively it helps control yaw.

I recorded DVR but it is hard to tell that I am using head tracking for yaw. We also discussed that it would be nice to have the head tracking for yaw have a dead-band in the center to allow finding center to be a little easier, as at higher weight/sensitivity it was difficult to find center and get yaw to completely stop. It was a pretty cool exploration and I attribute it to Jamie’s feedback and encouragement, especially considering I could’ve done it anytime since starting to use head tracking, but hadn’t.

Later in the day I started working on creating a custom curve to allow dead-band in the center, as well as doing some test flights with various ‘weights’ for the yaw mix to try and find the sweet spot. The pics bellow show my curve and channel mixes.

I did a flight later in the day where I hovered near myself, and you can see the yaw working as I turn my head, here’s a clip from that DVR:

That’s all I have on this for now, I am not sure if it is something I will actually want to use but it is good to have finally tried it and I will leave the configuration in place with a switch to enable it even if only for those who want to try flying with it to give it a shot.

UPDATE 11/23/22:

STRIKING FPV got a working version of the ‘velocity based control’ I mentioned earlier in this article. He made a video on it I am linking bellow, will be getting this working on my ‘try it out’ rig as the current yaw control via position isn’t particularly usable. His video includes a guide for anyone wanting to try it!