Prioritized Control Allocation for Quadrotors Subject to Saturation

This paper deals with the problem of actuator saturation for INDI (Incremental Nonlinear Dynamic Inversion) controlled flying vehicles. The primary problem that arises from actuator saturation for quadrotors, is that of arbitrary control objective realization. We have integrated the weighted least squares control allocation algorithm into INDI, which allows for prioritization between roll, pitch, yaw and thrust. We propose that for a quadrotor, the highest priority should go to pitch and roll, then thrust, and then yaw. Through an experiment, we show that through this method, and the appropriate prioritization, errors in roll and pitch are greatly reduced when applying large yaw moments. Ultimately, this leads to increased stability and robustness.