Controllability Analysis and Degraded Control for a Class of Hexacopters Subject to Rotor Failures

TL;DR

This paper analyzes the controllability of hexacopters under rotor failures and proposes a fault-tolerant control strategy for degraded systems, validated through simulations and experiments.

Contribution

It provides a novel controllability analysis for hexacopters with rotor failures and introduces a fault-tolerant control method for degraded control.

Findings

Hexacopters become uncontrollable with a single rotor failure despite over-actuation.

Degraded control is feasible when maximum rotor lift exceeds a certain threshold.

Simulation and experimental results confirm the effectiveness of the proposed control strategy.

Abstract

This paper considers the controllability analysis and fault tolerant control problem for a class of hexacopters. It is shown that the considered hexacopter is uncontrollable when one rotor fails, even though the hexacopter is over-actuated and its controllability matrix is row full rank. According to this, a fault tolerant control strategy is proposed to control a degraded system, where the yaw states of the considered hexacopter are ignored. Theoretical analysis indicates that the degraded system is controllable if and only if the maximum lift of each rotor is greater than a certain value. The simulation and experiment results on a prototype hexacopter show the feasibility of our controllability analysis and degraded control strategy.