How to Double the Yaw Inertia of a DJI Mini2, to Dampen Jerky Videos

There are many threads in this forum about jerky videos during yaw turns of a Mini2, and I have contributed to a number of them. One possible contributing factor floated for these jerks is the relatively low yaw moment of inertia for this tiny drone, coupled with the rather coarse virtual stick frame rate sending commands to the drone during flights. To test this theory, I added outrigger weights to the Mini2 that raised its yaw inertia from a measured 8,130 gm-cm^2 up to 19,613 gm-cm^2, a factor of 2.4 or so. With very limited testing, I can see no difference between videos of yaw sweeps using DJI Fly and those using Litchi, each being “butterly smooth” as we like to say.
The outrigger was made from two soda straws with 5/16" bolts on the ends, connected to the drone with coffee stirrers at the drone center of mass. The combined weight of the bolts was only 19 grams, so the drone flew well. I measured the yaw inertias of the two configurations using a Bifiliar Tortional Pendulum, a fancy term for a pendulum with two strings supporting the drone. The inertia is calculated as I = MgT^2b^2/(16Pi^2*L), where M is the support mass, g is the acceleration due to gravity, T is the period of torsional oscillation, b is the distance between the strings, and L is the pendulum length. Here’s a picture of the rig with the upside-down drone at the bottom:


If I can figure out how to post a video of the rig in action, I will do so. Lots more testing to do, but promising early results.

That’s a very ingenious solution to the problem. Please keep us posted on your finding. Here we were looking for an electronic solution and you’ve provided a mechanical solution.

Yep, guilty, I’m a mechanical engineer, but do ESP32 electronics and software and have a 3d printer too. So I’m very dangerous in what I will try. I now have a little more flying experience under my belt, and I still see some lumpiness in the really slow yaw scans, but it looks different. Next step is to raise the yaw MOI even more (maybe 5X nominal) and see what happens. The Mini2 flies the same in all other regards with the extra 19 grams of mass. Just the yaw and roll axes are seeing the extra MOI, not the pitch axis.