Multicopter attitude control for recovery from large disturbances
This work addresses safety-critical recovery scenarios for multicopters, though it appears incremental as it builds on and improves existing control methods.
The paper tackles the problem of multicopter attitude control for recovery from large disturbances by proposing a novel controller that prioritizes thrust direction error, showing it outperforms an existing similar controller in experiments.
We present a novel, high-performance attitude control law for multicopters, with a view to recovery from large disturbances. The controller is compared to three well-established alternatives from the literature. All controllers considered are identical to first order, but differ in their computation of the attitude error. We show that the popular use of the skew-symmetric part of the rotation matrix is problematic from a safety perspective, and specifically that the closed loop system may linger at large attitude errors for an arbitrary duration (leading to potential failures of practical systems). The novel proposed controller prioritizes the error in the vehicle thrust direction, and is shown to outperform a similar, existing controller from the literature. Stability follows via a Lyapunov function, and the controller is validated in experiments. This novel controller is especially attractive in safety-critical situations, where a multicopter may be required to recover from large initial disturbances.