Characterizing pitch and roll torque coupling in insect-sized flapping-wing robots using a microfabricated gimbal

2026-04-23

AI Summary

This study addresses the challenge of quantifying pitch-roll moment coupling in sub-gram flapping-wing aerial robots, which has been hindered by the absence of high-sensitivity dual-axis torque sensors. The authors propose a micromachined gimbal mechanism that enables, for the first time, high-precision simultaneous measurement of pitch moment, roll moment, and thrust. Integrated with a piezoelectric-driven flapping-wing platform and analyzed using linear regression and cross-correlation methods, experimental results demonstrate excellent linearity with coefficients of determination (R²) of 0.95 and 0.98 for pitch and roll moments, respectively. Crucially, the cross-coupling coefficients are nearly zero, and thrust fluctuations remain within 5.8% of the mean, confirming that pitch and roll moments can be approximately controlled independently. These findings provide critical experimental validation for decoupled control strategies in miniature flapping-wing vehicles.

Technology Category

• Intelligent Robots: Manipulation
• Planning, Routing, and Scheduling: Activity and Plan Recognition
• Application Domains: Mobility, Driving & Flight

Application Category

• Responsible Web: Machine-in-the-loop, human agency and autonomy
• Security and Privacy: Large-scale security measurements
• Web Mining and Content Analysis: Web measurements

Abstract

Sub-gram flapping-wing flying insect robots (FIRs) are challenging to model because of mechanical complexity in their wings, unsteady aerodynamic flow, and the difficulty of making precise measurements at a small scale. Coupling effects between roll and pitch torque actuation have not previously been measured because a two-axis sensor that is sensitive enough has not been realized. To address this shortcoming, we introduce a microfabricated gimbal design capable of precisely and simultaneously measuring roll and pitch torques as well as thrust. We then used it to measure the extent to which a pitch torque command affects roll torque and vice versa on a 180 mg piezo-actuated flapping-wing flying platform. Our results show a high coefficient of determination in the linear regression for both pitch (0.95) and roll (0.98) and low cross-correlation coefficients (-0.001 and -0.085, respectively) across the full range of simultaneous torque commands, indicating negligible cross-axis coupling. Similarly, thrust force deviates by a maximum of only 5.8% from the mean thrust value. These results validate the assumption that pitch and toll can be considered independently in control and will inform future models of how inputs affect the aerodynamics of resonant flapping-wing systems.

Problem

• flapping-wing robots
• torque coupling
• pitch and roll
• microfabricated sensor
• aerodynamic modeling

Innovation

• microfabricated gimbal
• torque coupling
• flapping-wing robot
• pitch-roll decoupling
• sub-gram aerial robot