A 26-Gram Tailless Butterfly-Inspired Flapping-Wing Robot with Onboard Attitude Control

Abstract

Butterfly-inspired flapping-wing robots use broad compliant wings and low-frequency actuation, but pronounced wingbeat-synchronous body dynamics and time-varying inertia complicate onboard control. Here, we introduce AirPulse, a 26 g two-winged tailless flapping-wing robot with integrated venation-inspired wings, sensing, computation, and power, representing the lowest flight-ready mass among compared butterfly-inspired platforms. We analyze the robot's dynamic structural coupling and map prescribed modulation parameters of flapping kinematics to experimental six-axis wrench profiles for systematic control channel allocation. To enable stable flapping motion, we formulate Stroke Timing Asymmetry Rhythm (STAR), a phase-domain modulation strategy that ensures smooth stroke velocity changes while preserving mean flapping frequencies. Coupled with state estimation, the onboard feedback control architecture demonstrates successful untethered pitch and directional tracking during climbing and turning maneuvers. Ultimately, the AirPulse robot offers an experimentally validated framework for stabilizing strongly oscillatory, low-mass bio-inspired platforms, providing a basis for future operation in sensitive, confined environments.