# Attitude Control of a Novel Tailsitter: Swiveling Biplane-Quadrotor

## TL;DR

This paper introduces a novel swiveling biplane-quadrotor design that overcomes yaw control limitations in traditional tailsitters, with a geometric control approach ensuring stable attitude tracking demonstrated through simulations and flight tests.

## Contribution

It presents a new vehicle design with a swivel mechanism for yaw control and a geometric control method for attitude tracking, addressing underactuation issues.

## Key findings

- Successful numerical simulations demonstrating control effectiveness
- Flight tests confirming practical viability
- Almost-global asymptotic stability achieved

## Abstract

This paper proposes a solution to the attitude tracking problem for a novel quadrotor tailsitter unmanned aerial vehicle called swiveling biplane quadrotor. The proposed vehicle design addresses the lack of yaw control authority in conventional biplane quadrotor tailsitters by proposing a new design wherein two wings with two attached propellers are joined together with a rod through a swivel mechanism. The yaw torque is generated by relative rotation of the thrust vector of each wing. The unique design of this configuration having two rigid bodies interconnected through a rod with zero torsional rigidity makes the vehicle underactuated in the attitude configuration manifold. An output tracking problem is posed which results in a single equivalent rigid body attitude tracking problem with second-order moment dynamics. The proposed controller is uniformly valid for all attitudes and is based on dynamic feedback linearization in a geometric control framework. Almost-global asymptotic stability of the desired equilibrium of the tracking error dynamics is shown. The efficacy of the controller is shown with numerical simulation and flight tests.