Liquid-amplified zipping actuators for micro-air vehicles with transmission-free flapping

Tim N Helps*, Christian P Romero, Majid Taghavi, Andrew T Conn, Jonathan M Rossiter*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

24 Citations (Scopus)
391 Downloads (Pure)


Flapping micro air vehicles (MAVs) allow access to a wide range of locations, including confined and high-risk spaces such as the inside of industrial plants and collapsed buildings, and offer high maneuverability and tolerance to disturbances. However, current flapping MAVs require transmission systems between their actuators and wings, which inevitably introduce energetic losses and additional mass, hindering performance. In this article, we introduce a high-performance electrostatic flapping actuation system, the Liquid-amplified Zipping Actuator (LAZA), which induces wing movement by direct application of liquid-amplified electrostatic forces at the wing root, eliminating the requirement of any transmission system and their associated downsides. The LAZA allows for accurate control of flapping frequency and amplitude, exhibits no variation in performance over more than one million actuation cycles, and delivers peak and average specific powers of 200 and 124 W kg-1 respectively, exceeding mammalian and insect flight muscle and on par with modern flapping MAV actuation systems. The inclusion of 50 mm long passively pitching wings in a dragonfly-sized LAZA flapping system allowed the rectification of net directional thrust up to 5.73 mN. This thrust was achieved while consuming only 243 mW of electrical power, implying a thrust-to-power ratio 23.6 N kW-1, similar to state-of-the-art flapping MAVs, helicopter rotors and commercial drone motors. Finally, a horizontally moving LAZA flapping system was able to accelerate from at-rest and travel at speeds up to 0.71 m/s (around 18 body lengths per second). The LAZA will enable a new class of low-cost, lightweight, high-performance transmission-free flapping MAVs for long-term remote exploration and search-and-rescue missions.
Original languageEnglish
Article numbereabi8189
JournalScience Robotics
Issue number63
Publication statusPublished - 2 Feb 2022

Bibliographical note

Funding Information:
Last, to evaluate the potential for LAZA-generated thrust to deliver flight, a horizontally moving LAZA system was constructed (Fig. 6A). Electrical power was provided by lightweight enameled copper wires, and the weight of the LAZA system was supported by

Publisher Copyright:
© 2022 American Association for the Advancement of Science. All rights reserved.


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