H-ModQuad: Modular Multi-Rotors with 4, 5, and 6 Controllable DOF

TL;DR

H-ModQuad is a modular multi-rotor system that can adapt its payload and controllable degrees of freedom by assembling different modules, enabling enhanced versatility and performance in aerial tasks.

Contribution

This work introduces a novel modular design allowing multi-rotors to increase controllable degrees of freedom from 4 to 6 by connecting heterogeneous modules.

Findings

Validated with real robot experiments

Demonstrated increased payload capacity

Showed independent translation and orientation control

Abstract

Traditional aerial vehicles are usually custom-designed for specific tasks. Although they offer an efficient solution, they are not always able to adapt to changes in the task specification, e.g., increasing the payload. This applies to quadrotors, having a maximum payload and only four controllable degrees of freedom, limiting their adaptability to the task's variations. We propose a versatile modular robotic system that can increase its payload and degrees of freedom by assembling heterogeneous modules; we call it H-ModQuad. It consists of cuboid modules propelled by quadrotors with tilted propellers that can generate forces in different directions. By connecting different types of modules, an H-ModQuad can increase its controllable degrees of freedom from 4 to 5 and 6. We model the general structure and propose three controllers, one for each number of controllable degrees of freedom. We extend the concept of the actuation ellipsoid to find the best reference orientation that can maximize the performance of the structure. Our approach is validated with experiments using actual robots, showing the independence of the translation and orientation of a structure.