"Just One Out of 100 is Enough"... A Remark by US Military Provoking Korean Scientist [Reading Science]

[Interview] August Scientist of the Month Award Winner Professor Park Hooncheol of Konkuk University
"Dedicated 15 Years to Developing Insect-Type Flying Vehicle Technology"
"Decision to Develop New Technology Inspired by a Single Word from an American Scientist"

[Asia Economy Reporter Kim Bong-su] A "beetle-type" flying vehicle capable of flying in thin atmospheres such as low Earth orbit or Mars by physical wing flapping without consuming excessive fuel like a rocket has been developed by Korean researchers. It does not crash even when colliding with obstacles, making it suitable for reconnaissance or nature filming. The protagonist is "KU Beetle," developed last year by Professor Park Hoon-chul of Konkuk University.

Professor Park focused on the biological characteristics of the stag beetle, which usually folds its wings multiple times to hide them and only unfolds them during flight. After 15 years of persistent research, he developed the "KU Beetle." The goal is to develop a flying vehicle that can fly in low-density atmospheres of extraterrestrial planets like Mars, where the atmospheric density is only 1/70th that of Earth's, by utilizing insect wing flapping.

Below is a Q&A with Professor Park, who received the "Science and Technology Person of the Month" award from the Ministry of Science and ICT in August.

▲ Congratulations on the award. How do you feel and what are your recent activities?

= Honestly, when I first started the research, I did not expect to succeed in controlled flight of a tail-less insect-mimicking flapping wing robot before retirement. I also did not expect to publish the research results in the journal Science. Of course, I never anticipated receiving the "Science and Technology Person of the Month" award. This achievement is thanks to the master's and doctoral students who worked hard for over 15 years to develop insect-mimicking flapping wing robots. This year marks the end of research projects related to insect-mimicking flying robots, so I am preparing new projects for follow-up research such as low-density atmospheric flight. I am also conducting research mimicking the characteristic of flying fish leaping from water into the air.

▲ You are researching flight that mimics insect flight?

= Insects fly based on principles different from aircraft or birds. Bird-mimicking flapping wing robots generate control moments necessary for posture maintenance from tail wings like birds or aircraft. In contrast, tail-less insects generate aerodynamic forces and control forces necessary for flight and posture maintenance solely by wing flapping. They produce more lift than predicted by conventional aerodynamics. Focusing on this feature, research on insect flight as a method of flying in the low-density atmosphere of Mars rapidly progressed in the early 2000s. However, insect flight is technically more difficult to mimic than bird flight, so flapping wing robots without tail wings that have succeeded in controlled flight for more than 5 minutes using an internal battery are still rare worldwide. Currently, on Mars, rotary-wing UAVs with a pair of wings rotating rapidly in opposite directions fly instead of flapping wings. The flight efficiency of insect-mimicking flying robots does not yet reach that of real insects, and many researchers are seeking solutions.

▲ What inspired your interest in small insects in nature?

= At the end of the 20th century, when aircraft and rockets dominated aerospace research, UAVs began to emerge one after another. In 2002, the American Institute of Aeronautics and Astronautics held its first UAV conference. At that time, the new research supported by the U.S. Defense Advanced Research Projects Agency was unprecedentedly unrealistic, and many American professors attending the conference expressed dissatisfaction. However, when a U.S. Air Force captain attending the panel discussion said, "We think it's enough if only one out of 100 funded projects succeeds," the room fell silent. I also got goosebumps from his words. From then on, I wanted to try something new. Shortly after, while walking by a lake at Konkuk University, I saw a ladybug folding and unfolding its wings to fly. Although I had seen this often before, strangely, that day it appeared as if a slow-motion video was playing before my eyes. It was amazing that the insect's wings, which have no muscles connected, could fold and unfold to enable flight. I thought of mimicking this and started research mimicking the flight and wing folding-unfolding of the stag beetle.

▲ Please introduce the research results of the beetle-type flying vehicle published in a paper last year.

= The paper contains two main topics. One is about the unfolding of the stag beetle's wings and collision energy absorption, and the other is the engineering mimicry of this. The stag beetle starts flapping its wings with only the forewings fully unfolded and the outer part of the hindwings folded. It was first reported that the aerodynamic and inertial forces generated by this initial flapping contribute to fully unfolding the hindwings. Furthermore, the fully unfolded hindwings, due to a central collision energy absorption mechanism, can fold the outer part of the hindwings upon collision with obstacles during flapping flight but quickly unfold again within a short time, allowing stable flight to continue, as demonstrated by flight experiments with stag beetles.

Secondly, mimicking the stag beetle's hindwings, a wing was developed with a collision energy absorption device composed of superelastic shape memory alloy wire and a hinge structure that stores collision energy as elastic energy in the front part of the wing. The outer part can fold in the wing plane and vertical direction. When colliding with an obstacle, the superelastic shape memory alloy wire folds around the hinge structure, storing collision energy as elastic energy. This wing was mounted on the insect-mimicking flapping wing robot (KU Beetle), and flight tests demonstrated stable flight even when the outer wing collided with obstacles.

▲ What memorable challenges did you face during the research process?

= Initially, the top priority was to develop a motor-driven flapping device capable of stable flapping over 180 degrees like the stag beetle. All devices had to be developed as simply and lightly as possible to enable flight. A method to automatically rotate the wings also had to be devised. After enabling large-angle flapping and automatic wing rotation, technology was needed to predict the aerodynamic forces generated by such flapping. Even if aerodynamic forces sufficient for flight are generated by flapping, control moments to maintain posture are necessary for stable flight. Unlike birds, insect-mimicking flying robots have no tail wings, so the wing trajectory must be continuously changed during flapping to generate both aerodynamic and control forces simultaneously. Next, feedback electronic control technology was required. By combining ultra-small electronic components used in small drones, a feedback control system was configured, achieving about 40 seconds of controlled flight in 2016. The control system implemented on an improved 1g integrated electronic board was developed in the laboratory of Professor Kang Tae-sam at Konkuk University's Department of Mechanical and Aerospace Engineering. In 2019, the KU Beetle equipped with this system succeeded in about 9 minutes of flight, setting the longest flight time among insect-mimicking flapping wing robots developed in university laboratories worldwide.

▲ What was the biggest obstacle?

= Above all, observing insect flight was difficult. Observing the movement of small insect wings was even more challenging. This is why the relatively large stag beetle was chosen as the research subject. However, stag beetles are nocturnal and only fly at night. Digital ultra-high-speed cameras using very bright light sources were needed to film the stag beetle's flight, but the light source prevented the beetles from flying even at night. It took a lot of effort and time to make the stag beetles fly and to film them. Moreover, insects are hard to tame, so even if they flew, they did not fly in the desired direction. Great patience was required to use various ideas and repeated experiments to make the stag beetles fly in specific directions.

▲ How can the research results be utilized?

= Insect-mimicking flying robots fly based on principles different from drones driven by multiple propellers. Their appearance and flight principles are relatively nature-friendly. If such robots perform functions similar to current drones, entirely different types of drones could be utilized in reality. Alternatively, they could be used differently due to limited flight time or performance. The KU Beetle might perform covert missions without being detected by enemies. Currently, many defense-related organizations have shown great interest. However, additional research is still needed for practical use. It can also be used as educational material explaining insect flight principles.

▲ What goals do you want to challenge in the future?

= The research so far has been an extremely difficult challenge, but many ask what the next challenge is. If I had more time and resources, I would like to research dual-mode robots mimicking creatures that move in two or more ways, such as locusts, flying fish (gongginori), and cormorants. The locust-mimicking robot has achieved some results but not satisfactory ones, and research on flying fish mimicry has just begun. Research on cormorant mimicry was proposed last year but did not receive good evaluations due to lack of preparation. In the short term, I plan to conduct research using the insect-mimicking flying robot KU Beetle to fly at altitudes where air density is about 70% of sea-level air density. If conditions permit, I will study methods for flying in even lower air densities and improving flight efficiency.

▲ Any advice for students dreaming of becoming future scientists?

= Scholarship is the greatest intangible world cultural heritage left and to be left by humanity. Among them, science is the greatest cultural heritage that has extended human life and advanced material civilization. Contributing to inheriting and developing this discipline called science is both the right and duty of future scientists.

This content was produced with the assistance of AI translation services.