Gimballed Rotor Mechanism for Omnidirectional Quadrotors
J. Cristobal, A. Z. Zain Aldeen, M. Izadi, R. Faieghi
TL;DR
The paper addresses the underactuation of conventional MRUAVs by introducing a four-rotor gimballed mechanism that tilts each rotor via onboard servos, integrated with PX4/ROS to realize an $SE(3)$-capable omnidirectional quadrotor. The approach combines a modular rotor design, a derived 6-DOF dynamic model, and a PX4-based control allocation that computes $u = B^{\dagger} v$ and derives $T_i$, $\Omega_i$, and $\beta_i$ for actuation. Key contributions include the gimballed rotor hardware, the accompanying dynamic model, the modified control framework, and indoor flight demonstrations demonstrating level attitude maintenance and lateral maneuverability with minimal frame modification. This work offers a lightweight, repairable, and accessible path to omnidirectional flight using off-the-shelf components and standard software, broadening the practical deployment of omnidirectional quadrotors in constrained environments.
Abstract
This paper presents the design of a gimballed rotor mechanism as a modular and efficient solution for constructing omnidirectional quadrotors. Unlike conventional quadrotors, which are underactuated, this class of quadrotors achieves full actuation, enabling independent motion in all six degrees of freedom. While existing omnidirectional quadrotor designs often require significant structural modifications, the proposed gimballed rotor system maintains a lightweight and easy-to-integrate design by incorporating servo motors within the rotor platforms, allowing independent tilting of each rotor without major alterations to the central structure of a quadrotor. To accommodate this unconventional design, we develop a new control allocation scheme in PX4 Autopilot and present successful flight tests, validating the effectiveness of the proposed approach.