Motion Control and Power Distribution of H-Shaped Multi-Modal Transformable Rotorcraft

Abstract

Multilink transformable rotorcraft demonstrate exceptional flexibility when navigating confined spaces, yet face critical challenges including time-varying center of gravity, body misalignment, and the absence of a unified control strategy during dynamic reconfiguration, which severely restrict motion continuity and operational capability. To address these limitations, we propose an H-shaped multi-modal transformable rotorcraft. Its novelty lies in the co-design of a specialized mechanical architecture with 6 controllable degrees of freedom (CDOF) and an integrated control allocation framework, enabling the aircraft to achieve stable and continuous aerial transitions between high-passability, high fault-tolerance, and high-torque configurations. A dynamic PID control law based on motion characteristic values ensures system robustness against uncertainties, while a novel competency-based power distribution strategy uniquely constrains propeller thrust and lever arms to generate feasible control commands for each configuration. Experimental results demonstrate that our platform successfully overcomes stability challenges, maintaining positional deviation within 0.04 m during traversal through constrained spaces. The aircraft can reduce its footprint by up to 55.8%, sustain flight under single-propeller failure, and switch to a fault-tolerant configuration within 1.2 seconds, while exhibiting high-torque output capability sufficient for rotational operations. This work provides a comprehensive ontological platform that effectively bridges the technological gap between transformable reconfiguration and fault-tolerant control, enabling multi-scenario operational capabilities.