DJI E310 Thrust Coefficient

Question

I am reading Denis M. Filatov et al.'s paper "Parameters identification of thrust generation subsystem for small unmanned aerial vehicles" (https://www.semanticscholar.org/paper/Parameters-identification-of-thrust-generation-for-Filatov-Friedrich/9ec916f9907810e41368f1ac2a6885a0bf2c2ee4). I need to use their characterization data of the DJI E310 motors for my undergraduate research project dealing with a quadcopter. In Table I, their unit for torque is "mH m". I assumed that this was a typographical error since the symbol H represents the SI unit for inductance and that the authors meant "mN m". With this assumption, I then took the torque-to-force ratio of their first data point in $\frac{N\cdot m}{N}$ and got $1.6\times10^{-03}$. The ratio that Mark W. Mueller et al. found in their paper "Stability and control of a quadrocopter despite the complete loss of one, two, or three propellers" (https://flyingmachinearena.org/wp-content/publications/2014/mueIEEE14.pdf) was $1.69\times10^{-2}$. This is more than ten times higher than from the ratio I computed in Filatov et al.'s data. I simulated a quadcopter using the same DJI E310 420s motors and F450 body frame that Filatov et al. used. The minimum settling time for the yaw PID control turned out to be $30s$ which is absurdly way too long compared with the settling time I observe in experience which is usually within $5s$. Did the authors mean "N m" or anything else? My analysis tells me that "mN m" would make their torque readings too low compared with what standard quadcopters using DJI E310 and DJI F450 would give. I tried emailing the authors to clarify this but I got no response. I hope someone with experience or who knows the answer can help me on this.

Answer 1

I found a new paper titled "Quadrotor Parameters Identification and Control System Design" (https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=7910684) by the same authors published on the same year, presumably using the same quadcopter platform. They provided formulas relating torque in Newton-meters and PWM percentage from 0 to 100. The results in "Parameters identification of thrust generation subsystem for small unmanned aerial vehicles", using "mN m" or milliNewton-meter as a unit for the torque instead of the typographical error "mH m", match with their formulas in "Quadrotor Parameters Identification and Control System Design".