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Insect-Scale Tailless Robot with Flapping Wings: A Simple Structure and Drive for Yaw Control

Tomohiko Jimbo, Takashi Ozaki, Norikazu Ohta, Kanae Hamaguchi

TL;DR

The paper tackles yaw control in insect-scale tailless flapping-wing MAVs by introducing a four-paired tilted-wing design driven directly by piezoelectric actuators. It develops a control-oriented model with unknown lift-offsets, analyzes controllability via a Gramian, and designs an adaptive controller to compensate offsets, outperforming an LQI baseline in simulations. Numerical results and a tethered flight demonstration show yaw drift suppression and robust attitude/vertical control, suggesting potential for untethered, battery-powered flights below 10 g. The work combines a simple, transmission-free actuation scheme with adaptive control to enable reliable yaw control in ultra-light flapping-wing robots, paving the way for practical, safe operation in constrained environments.

Abstract

Insect-scale micro-aerial vehicles, especially, lightweight, flapping-wing robots, are becoming increasingly important for safe motion sensing in spatially constrained environments such as living spaces. However, yaw control using flapping wings is fundamentally more difficult than using rotating wings. In this study, an insect-scale, tailless robot with four paired tilted flapping wings (weighing 1.52 g) to enable yaw control was fabricated. It benefits from the simplicity of a directly driven wing actuator with no transmission and a lift control signal; however, it still has an offset in the lift force. Therefore, an adaptive controller was designed to alleviate the offset. Numerical experiments confirm that the proposed controller outperforms the linear quadratic integral controller. Finally, in a tethered and controlled demonstration flight, the yaw drift was suppressed by the wing-tilting arrangement and the proposed controller. The simple structure drive system demonstrates the potential for future controlled flights of battery-powered, tailless, flapping-wing robots weighing less than 10 grams.

Insect-Scale Tailless Robot with Flapping Wings: A Simple Structure and Drive for Yaw Control

TL;DR

The paper tackles yaw control in insect-scale tailless flapping-wing MAVs by introducing a four-paired tilted-wing design driven directly by piezoelectric actuators. It develops a control-oriented model with unknown lift-offsets, analyzes controllability via a Gramian, and designs an adaptive controller to compensate offsets, outperforming an LQI baseline in simulations. Numerical results and a tethered flight demonstration show yaw drift suppression and robust attitude/vertical control, suggesting potential for untethered, battery-powered flights below 10 g. The work combines a simple, transmission-free actuation scheme with adaptive control to enable reliable yaw control in ultra-light flapping-wing robots, paving the way for practical, safe operation in constrained environments.

Abstract

Insect-scale micro-aerial vehicles, especially, lightweight, flapping-wing robots, are becoming increasingly important for safe motion sensing in spatially constrained environments such as living spaces. However, yaw control using flapping wings is fundamentally more difficult than using rotating wings. In this study, an insect-scale, tailless robot with four paired tilted flapping wings (weighing 1.52 g) to enable yaw control was fabricated. It benefits from the simplicity of a directly driven wing actuator with no transmission and a lift control signal; however, it still has an offset in the lift force. Therefore, an adaptive controller was designed to alleviate the offset. Numerical experiments confirm that the proposed controller outperforms the linear quadratic integral controller. Finally, in a tethered and controlled demonstration flight, the yaw drift was suppressed by the wing-tilting arrangement and the proposed controller. The simple structure drive system demonstrates the potential for future controlled flights of battery-powered, tailless, flapping-wing robots weighing less than 10 grams.
Paper Structure (23 sections, 2 theorems, 29 equations, 9 figures, 3 tables)

This paper contains 23 sections, 2 theorems, 29 equations, 9 figures, 3 tables.

Table of Contents

  1. Introduction
  2. Modeling
  3. Tilted-wing arrangement and yaw torque generation
  4. Representation of unknown offsets
  5. Flight dynamics
  6. Control-oriented formulation
  7. Controllability
  8. Flight controller
  9. Velocity control
  10. Attitude control
  11. Vertical control
  12. Lift-force demand and flapping-amplitude control
  13. Simulation
  14. Controllability analysis
  15. Simulation setup
  16. ...and 8 more sections

Key Result

Theorem 1

On applying the control input of (eq:adapt_tau) and the adaptive law of (eq:adapt_tauo) with (eq:s_omega) to (eq:Euler) and (eq:tau-delay), the sliding variable $s_\omega$ satisfies $s_\omega \rightarrow 0$ as $t \rightarrow \infty$.

Figures (9)

  • Figure 1: Flapping-wing robot fabricated with four paired wings tilted by $\beta=20$ degree and $\gamma=60$ degree, equipped with eight piezoelectric actuators, a glass-fiber-reinforced plastic body, carbon-fiber-reinforced plastic legs, a wingspan of $110$ mm, and a weight of $1.52$ g.
  • Figure 2: Wing arrangement and lift force direction
  • Figure 3: Controllability Gramian $BB^\top$
  • Figure 4: Step responses. The diamonds, circles, and squares represent delay, overshoot of $10 \%$ or greater, and settling times, respectively.
  • Figure 5: Performance metrics
  • ...and 4 more figures

Theorems & Definitions (4)

  • Theorem 1
  • proof
  • Theorem 2
  • proof