Reconfigurable Control of a Class of Multicopters

TL;DR

This paper introduces a reconfigurable control scheme for multicopters that maintains controllability despite rotor failures by using a new control authority index and a nonlinear control approach, demonstrated through simulations.

Contribution

It proposes the Available Reduced-Control Authority Index (ArCAI) and a reconfigurable control scheme for multicopters facing rotor failures, enhancing fault tolerance.

Findings

Control scheme maintains stability under rotor failures.

Simulation shows effective control with multiple rotor failures.

New index improves controllability assessment.

Abstract

In this paper, a reconfigurable control scheme for a generalized class of multicopters is presented to overcome single or multiple rotor failures. In a multicopter, the rotor failure heavily affects its dynamics and thus its controllability. Limited controllability leads to limited or no reconfigurability. \emph{Available Control Authority Index} has been recently developed \cite{Du2015} as a measure of controllability of multicopters. In this work, the notion of \emph{Available Reduced-Control Authority Index} (ArCAI) is introduced, which shows that in some uncontrollable failures it is still possible to control reduced set of states. Based on this notion, a reconfigurable control scheme is presented, which comprises a \emph{Nonlinear Dynamic Inversion} based baseline control law, a constrained control allocation scheme along with some modifications to incorporate reconfiguration, and a simplified fault detection and isolation technique. Simulation results for a commonly used configuration of Hexacopter are presented in the presence of single and multiple rotor failures.