From Propeller Damage Estimation and Adaptation to Fault Tolerant Control: Enhancing Quadrotor Resilience

TL;DR

Propeller damage poses a critical challenge for quadrotor resilience. The authors develop a cascaded geometric controller augmented with an L1 adaptive scheme that both infers propeller damage and compensates for it, with an optimization based damage estimator and a seamless transition to fault tolerant control when damage is severe. The approach relies on an outer loop attitude/position controller and an inner loop attitude controller, plus a state predictor and a low pass filtered disturbance compensation, enabling real time operation without direct RPM measurements. Experimental results on a 700 g quadrotor show accurate damage estimation and reliable transitions to fault tolerant mode, outperforming standard PID baselines in damaged scenarios. The work demonstrates a practical pathway to robust aerial robotics under actuator degradation.

Abstract

Aerial robots are required to remain operational even in the event of system disturbances, damages, or failures to ensure resilient and robust task completion and safety. One common failure case is propeller damage, which presents a significant challenge in both quantification and compensation. We propose a novel adaptive control scheme capable of detecting and compensating for multi-rotor propeller damages, ensuring safe and robust flight performances. Our control scheme includes an L1 adaptive controller for damage inference and compensation of single or dual propellers, with the capability to seamlessly transition to a fault-tolerant solution in case the damage becomes severe. We experimentally identify the conditions under which the L1 adaptive solution remains preferable over a fault-tolerant alternative. Experimental results validate the proposed approach, demonstrating its effectiveness in running the adaptive strategy in real time on a quadrotor even in case of damage to multiple propellers.

Figures (9)

• Figure 1: L1 adaptive and fault-tolerant control with one damaged propeller (circled in red dash). The fault-tolerant controlled quadrotor is forced to spin (over $1000$ deg/sec).
• Figure 2: MAV model with inertial and body frame definitions.
• Figure 3: The cascaded control scheme, shows the L1 Adaptation Controller (blue), receives the partial state feedback from the system. The Fault Tolerant Controller (pink) is activated only once damage estimate exceeds $50\%$.
• Figure 4: A comparison between estimated damage and true damage with a real-world MAV during a $1.1~m/s$ flight. Propeller damage is estimated using eq. (\ref{['est_prop_dam']}). True Propeller damage is solved by measuring the coefficient on a thrust bench.
• Figure 5: Tracking RMSE averaged over 3 axes vs Propeller Damage at hover with various levels of propeller damage.