Aaron Roth C2

Behavior or Capability

The ability to hover mid-winged-flight would be an important capability for a flying robot to posses. In the wild, it allows hummingbirds and bees to drink the nectar of flowers. Winged flight is superior to rotary-blade flight because of increased maneuverability. ([22]) It is no mistake that nature’s beast gracefully glide through the air on wings. Many creatures, however, are unable to hover. A robot which flew with wings and could suspend itself midair with the same, would bring to the world a kind of grace heretofore unseen with regards to the mechanized world.

It would enhance robots’ abilities to perform whatever are its primary functions. A hovering robot could suspend itself near climbers trapped on a mountain cragg or in a crevice, allowing them to climb aboard and live another day. A hovering winged robot could also function as an effective companion or human aide. Although not discussed here, the winged movement would allow it to easily navigate the human environment with minimal habitat conceits to the robot. Such a machine that could hover could retrieve objects and transmit them from storage to person or from person to person, or act as a temporary table of variable height. Other potential robotic applications that would benefit from this addition are weather recording, spying, movie filming, and for use in war and machines of destruction.

Capabilities of Existing Technology

Existing technology is discussed by the authors of [1]. Their paper specifically addresses the issues of wing movement required for hovering. They tried to imitate insects’ hovering, which they describe as

“oscillating (plunging) and rotating … their wings through large angles, while sweeping them forwards and backwards.”

Noticing that the traced pattern resembled a figure eight with noticeable pitching, the authors elected to create a mechanism derived from a double-spherical Scotch yoke. They designed these wings with a robot in mind weighing 50 to 100 g, and on the order of 150 mm in size. The authors envisioned the advantage of these sorts of robots as being able to navigate enclosed spaces such as tunnels and shafts. They are aware, as they build, of many of the requirements for a successful hovering wing motion, such as stroke plane parallel to the fuselage.

Through experiments, the researchers collected data on the wings they created and determined how closely they approximated nature.

Potential Biological Solutions or Bioinspired Approaches

In [2], a study is made of a live dragonfly. As may have become apparent, insects are the optimal-winged hoverers to emulate. [1], [2], and others reiterate this fact.

The dragonfly has precise and powerful hovering ability.

[2] investigated the factors that make up a dragonfly wing and stroke. They discovered data that can be translated into improving machines, such as that the mean flapping frequency is 33.4 Hz, and that the stroke plane angle is 53° for the forewing and 44° for the hindwing. The inclined stroke plane orients the aerodynamic drag so as to balance the vertical force. The authors also determined specific angles can reduce the power in generating the required force, and at which specific phase of the wings need not be exact.

Value of Quality Sources

I found a great source at [4] early in the search. At first it seems like the ideal source. It is from a respectable conference, has a great 95 citations in Scopus, and includes multiple authors with h-indices in the 20s and 30s. Indeed, it is a very high quality paper but cannot be used as a main or up-to-date source because it is from 2000. It might be helpful to use advanced search features to weed out old papers. At the same time, they can be useful for giving the background on a subject.

In future, it also might be reasonable to search immediately for the specific biocapability instead of a general term such as “flight” which can give many other things. Certainly initially broad terms are reasonable, especially one is defining one’s objectives. Searching for “flight AND wing AND robot” brought me, among more directly relevant papers, [5]. It talks about artificial butterfly wings and robotic imitations of them. This is not of value to our more narrowly focused topic of winged hovering flight, since butterflys don’t hover.

Legitimacy issues can occur as well, such as with [3]. In this case, paper was attractive in terms of content and information. After researching the authors and venues, however, it became clear that this was not necessarily a quality paper. It is in the bottom quarter of industry journals. Redeeming factors include the fact that Brill, the publisher, was founded in 1683 and the fact that one author has PhD and is an Assistance Professor at University of Delaware, and who received an NSF career award in 2006. To avoid spending time analyzing a paper that does not have credentials satisfactory to satisfy one’s standards, one might consider running a quick check on the journal and authors before delving into reading the report.

Open Problems

One issue that has not been sufficiently dealt with is that of adding an additional payload. Robots built in the literature I discovered could, when they successfully hovered, support their own weight. Most of them could not have supported additional mechanical, electrical, or sensory components that added to the weight without adding to the flight ability.

As [3] points out, it is always beneficial to work towards minimizing the size and weight of the robot while increasing the flapping frequency, for the purpose of increasing lift generation.



[1] documents the efforts to build a wing system that would move in a way that it was thought wings should move to enable hovering, and would be subjected to the same forces, and documents the resulting measurements and data. [1] is published by the Journal of the Royal Society Interface, which has an impact factor of 4.241 for 2009. It is ranked 4th in JCR’s multidisciplinary category. The authors are Cezary Galiński and Rafał Żbikowski, who have h-indexes of 4 and 10, respectively.


As a precursor to [1], [11] deals with the mechanical energy required for flying in various conditions. For example, flies may require increased force production and so increase wing beat frequency and wing stroke amplitude. The publication American Zoologist has a SNIP of 1.100. One author of [11] has an h-index of 31, another has an h-index of 15.

Wings are useless without the proper body on which to mount them, as the authors of [12] knew. They developed a thorax structure and wings, focusing also on wing rotation. This paper was presented at the 2000 IEEE International Conference on Robotics and Automation. Authors include those with h-index 21 and nearly 2000 citations, and with an h-index of 31 and over 2000 citations.


The authors of [9] built a small machine that can perform a constrained hover based on [1]. The journal, Mechanism and Machine Theory, has an SNIP of 3.450. It was 150 mm in size, but weighed even lighter than anticipated at 3.2 g.

A new direction is pursued with [10], with the Scotch yoke and related efficiencies adopted for use in making dolphin-like robots. Once again, a paper from Mechanism and Machine Theory. Two of the 4 authors have h-indices of 9 and 11, respectively.

Biology (Bioinspiration)

[2] is published in Physical Review Letters, which has an impact factor of 7.328. David Russell has an h-index of 40 and Zhi Jane Wang has an h-index of 19.


[7] is a previous study of the lift forces associated with a tethered dragonfly. In particular, [7] came to the conclusion that the lift forces are made large by unsteady flow-wing interactions. It is published in Science, which has an SJR of 4.777 and an SNIP of 7.720.

The author of [8] created a computer algorithm which he claims shows that hovering flight is possible. [8] is also published in Physical Review Letters, which has an impact factor of 7.328.


[13] proceeds along a very similar vein as [2], utilizing the dual forewing/hindwing structure and investigating interactions therein, noticing those factors which contribute to increasing the total lift force and decreasing the drag. It is published by Physical Review E, with an impact factor of 2.4.

The dragonfly wing is further developed in [14], as the authors demonstrate the aerodynamic efficiency of the dual-wing-pair system. This is also published by the Royal Society Interface, and one author has an h-index of 15 and almost 1000 citations.


Some numbers omitted such that numbers here and in C1 match up.

1. Cezary Galiński and Rafał Żbikowski // Insect-like flapping wing mechanism based on a double spherical Scotch yoke // Journal of the Royal Society Interface, 2005, (2), pp. 223-235
Their paper specifically addresses the issues of wing movement required for hovering. This is the core capability that I focus on. Insect-like flapping wing mechanism
2. Z. Jane Wang and David Russell // Effect of Forewing and Hindwing Interactions on Aerodynamic Forces and Power in Hovering Dragonfly Flight // Physical Review Letters, 2007, Oct 5; 99, (14) article number 148101
This paper investigates the factors that make up a dragonfly wing and stroke. It watches a live dragonfly fly while tethered. Effect of Forewing and Hindwing Interactions
3. DiLeo C, Deng XY // Design of and Experiments on a Dragonfly-Inspired Robot // Advanced Robotics, 2009; 23, (7-8), pp. 1003-1021
This paper talks about building a winged robot and also touches upon what is left to accomplish in the field. Design of and Experiments on Dragonfly-Inspired Robot
4. Fearing, R.S., Chiang, K.H., Dickinson, M.H., Pick, D.L., Sitti, M., Yan, J // Wing transmission for a micromechanical flying insect // IEEE International Conference on Robotics and Animation, 2000. Volume 2, 1509-1516
Wing Transmission for MEMs insect
5. Tanaka, H., Matsumoto, K., Shimoyana, I. // Design and Performance of Micromolded plastic butterfly wings on butterfly ornithopter. // IEEE/RSJ International Conference on Intelligent Robots and Systems, IROS, 2008; pp. 3095 – 3100, article number is 4651. Vol 102, (50), December 2005, pp. 18213 - 18218
6. Altshuler, D.L. , Dickson, W.B. , Vance, J.T. , Roberts, S.P., Dickinson, M.H. // Short-amplitude high-frequency wing strokes determine the aerodynamics of honeybee flight. // Honeybee
This paper measures the flight of a honeybee.
7. Somps, C. Luttges M. // Dragonfly flight: Novel uses of unsteady separated flows // Science, Volume 228, Issue 4705, 1985, Pages 1326-1329
A precursor to a previous study of the lift forces associated with a tethered dragonfly. Dragonfly flight
8. Wang, Z Jane // Two Dimensional Mechanism for Insect Hovering // Phys. Rev. Lett. 85, 2216–2219 (2000)
Uses theory to show that hovering with wings is possible. This is important verification. Two Dimensional Mechanism
9. Fenelon, MAA; Furukawa, T // Design of an active flapping wing mechanism and a micro aerial vehicle using a rotary actuator // Mechanism and Machine theory, Volume 45, Issue 2, February 2010, Pages 137-146
This builds on [8] to construct MAVs. Active Flapping Wing
10. Yu, J; Hu, Y; Huo J; Wang L // Dolphin-like propulsive mechanism based on an adjustable Scotch yoke // Mechanism and Machine theory, Volume 44, Issue 3, March 2009, Pages 603-614
Taking this solution from the dragonfly that were going to be used for flying and using them for dolphins instead. Dolphin-like protrusion mechanism based on Scotch yoke
11. Dickenson, Lehmann, Chan // The control of mechanical power in insect flight // American Zoologist, Volume 38, Issue 4, 1998, Pages 718-728
Discusses the mechanical energy requires for various conditions. Mechanical power in insect flight
12. Fearing, RS, Chiang KH, Dickenson MH, Pick DL // Wing transmission for a micromechanical flying insect // IEEE International Conference on Robotics and Automation, Volume 2, 2000, Pages 1509-1516
Developed a thorax structure and wings, focusing also on wing rotation. Wing Transmission for Micromachine
13. Zhang, Jie; Lu, Xi-Yun // Aerodynamic performance due to forewing and hindwing interaction in gliding dragonfly flight // Physical Review E, 80, (1), 2009
Further investigates the dual forewing/hindwing structure, noticing those factors which contribute to increasing the total lift force and decreasing the drag. Aerodynamic forewing and hindwing
14. Usherwood, JR; Lehmann, F-O // Phasing of dragonfly wings can improve aerodynamic efficiency by removing swirl // Journal of the Royal Society Interface, Volume 5, Issue 28, 6 November 2008, Pages 1303-1307
The efficiency of the dual-wing setup is further demonstrated. Aerodynamic Phasing of Dragonfly Wings