Morph-EUS: Morphable OmnidirEctional Unmanned System

Ivan Bao*, José C. Díaz Peón González Pacheco*, Atharva Navsalkar*, Andrew Scheffer*, Sashreek Shankar*, Andrew Zhao*, Hongyu Zhou*, Vasileios Tzoumas
University of Michigan, *Ordered Alphabetically
ICRA 2025 OCRAIM Workshop
Paper

Our novel quadrotor offers omnidirectional control over position and orientation for improved inspection capabilities

Abstract

Omnidirectional aerial vehicles (OMAVs) have opened up a wide range of possibilities for inspection, navigation, and manipulation applications using drones. In this paper, we introduce MorphEUS, a morphable co-axial quadrotor that can control position and orientation independently with high efficiency. MorphEUS uses a paired servo motor mechanism for each rotor arm, capable of pointing the vectored-thrust in any arbitrary direction. As compared to the state-of-the-art OMAVs, we achieve higher and more uniform force/torque reachability with a smaller footprint and minimum thrust cancellations. The overactuated nature of the system also results in resiliency to rotor or servo-motor failures. The capabilities of this quadrotor are particularly well-suited for contact-based infrastructure inspection and close-proximity imaging of complex geometries. In the accompanying control pipeline, we present theoretical results for full controllability, almost-everywhere exponential stability, and thrust-energy optimality. We evaluate our design and controller using high-fidelity simulations showcasing the trajectory-tracking capabilities of the vehicle during various tasks.

CAD Model of the Quadrotor
Quadrotor CAD model with an additional primary joint and secondary joint per rotor

Method

We present a novel variable-tilt co-axial quadrotor and a control pipeline that achieves a significantly higher level of maneuverability, dexterity, and efficiency. This system builds on prior work by improving omnidirectional flight capabilities while avoiding inefficient thrust cancellations. To realize this, each of the rotor pairs can be independently oriented using a pair of servo motors. This allows for full 6-DoF control of position and orientation. In the paper, we prove that the proposed controller is exponentially stable almost everywhere and energy-optimal in terms of control allocation.

Drone Fabrication
Autonomous pipeline for the proposed variable-tilt morphable quadrotor.

Real World Testing

In future work, we plan to apply these algorithms in real-world experiments. Progress has already been made in this direction, including:

  1. Extending the algorithms to the PX4 software-in-the-loop flight stack

  2. Fabricating the drone

    Drone Fabrication
    Prototype of morphable quadrotor: 1. Dynamixel Servos, 2. NVIDIA Jetson Orin Nano, 3. Pixhawk 6x Flight Computer, 4. Intel RealSense Camera, 5. Coaxial Propellor Motors, 6. ESC + PDB Stack

  3. Conducting preliminary flight tests

    Preliminary Flight Test
    Preliminary, tethered flight test of the MorphEUS quadrotor using PX4 flight controller and VIO localization.

BibTeX

@inproceedings{iral2025morpheus,
    title     = {MorphEUS: Morphable OmnidirEctional Unmanned System},
    author    = {Ivan Bao and Jos{\'e} C. D{\'\i}az Pe{\'o}n Gonz{\'a}lez Pacheco and Atharva Navsalkar and Andrew Scheffer and Sashreek Shankar and Andrew Zhao and Hongyu Zhou and Vasileios Tzoumas},
    booktitle = {Proceedings of the ICRA 2025 OCRAIM Workshop},
    year      = {2025},
    note      = {To appear},
    url       = {https://iral-morphable.github.io/}
}