felixrising wrote:Submit a patch for a third controller based on LQR
Just reading through those papers... this stands out to me as a potential problem: "However, as a method the determination of PID parameters are easier to obtain using LQR method." people often struggle with PID tuning already. Also, it appears that although LQR achieves the desired state very quickly, some damping or de-tuning may be required for a multirotor application to allow the motors to change speeds at efficient rates and provide time to overcome inertia of the craft.
Yes I'm thinking the same thing. Such adjustment is necessary and not very difficult, after all people just tune the Q (or sometimes called Q1) most of the time, so we have only one parameter here, sounds very attractive. If the overshoot is too high, just reduce Q a little bit or increase R (Q2) until satisfied. Multiwii has already real time data reading in the GUI, this could help tuning a lot.
PID tuning can sometimes be very frustrating for people if the system has some bad poles at low frequency, like DJI frame that has soft arms. If it's not tuning right, one may crash his copter. LQR seems better at this point, not that easy to go crazy like a badly tuned PID though. BTW the lowpass filter of MultiWii does work very well with such frames onces it's set right.
