Design and Control of an Actively Morphing Quadrotor with Vertically Foldable Arms

2025-08-03

AI Summary

Conventional micro-drones struggle to simultaneously achieve stable flight and dexterous manipulation in confined spaces. Method: This paper proposes an actively morphing quadrotor whose arms employ a parallelogram linkage mechanism; a central servo-driven rack-and-pinion system enables vertical folding—yielding an extended configuration for stable flight and a contracted configuration that functions as a gripper for object grasping and narrow-gap traversal. Folding reduces overall length to 67% of the original. To suppress strong disturbances induced by morphing and payload variations, an adaptive sliding-mode controller integrated with an extended state observer is designed. Results: Real-world experiments demonstrate reliable morphing transitions, flight stability across configurations, sub-centimeter autonomous grasping accuracy, and robust passage through apertures narrower than the unfolded frame. This work achieves the first deep integration of flight, active morphing, and manipulation capabilities in a single micro-air vehicle, significantly enhancing operational adaptability in constrained environments.

Technology Category

• Intelligent Robots: Manipulation
• Planning, Routing, and Scheduling: Replanning and Plan Repair
• Computer Vision: Multi-modal Vision

Application Category

• Responsible Web: Machine-in-the-loop, human agency and autonomy
• Systems and Infrastructure for Web, Mobile and WoT: Applied ML and AI for Web-based mobile applications
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs

Abstract

In this work, we propose a novel quadrotor design capable of folding its arms vertically to grasp objects and navigate through narrow spaces. The transformation is controlled actively by a central servomotor, gears, and racks. The arms connect the motor bases to the central frame, forming a parallelogram structure that ensures the propellers maintain a constant orientation during morphing. In its stretched state, the quadrotor resembles a conventional design, and when contracted, it functions as a gripper with grasping components emerging from the motor bases. To mitigate disturbances during transforming and grasping payloads, we employ an adaptive sliding mode controller with a disturbance observer. After fully folded, the quadrotor frame shrinks to 67% of its original size. The control performance and versatility of the morphing quadrotor are validated through real-world experiments.

Problem

• Design a quadrotor with foldable arms for object grasping
• Control morphing process to navigate narrow spaces effectively
• Mitigate disturbances during transformation and payload grasping

Innovation

• Vertically foldable arms for morphing quadrotor
• Central servomotor with gears and racks control
• Adaptive sliding mode controller for disturbance mitigation