  The ability of aerial robots to operate in the presence of failures is
crucial in various applications that demand continuous operations, such as
surveillance, monitoring, and inspection. In this paper, we propose a
fault-tolerant control strategy for quadrotors that can adapt to single and
dual complete rotor failures. Our approach augments a classic geometric
tracking controller on $SO(3)\times\mathbb{R}^3$ to accommodate the effects of
rotor failures. We provide an in-depth analysis of several attitude error
metrics to identify the most appropriate design choice for fault-tolerant
control strategies. To assess the effectiveness of these metrics, we evaluate
trajectory tracking accuracies. Simulation results demonstrate the performance
of the proposed approach.
