Aerial+vehicles
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Robotic Herding of a Flock of Birds Using Drones
A joint team from KAIST, Caltech, and Imperial College London, presents a drone with a new algorithm to shepherd birds safely away from airports
Researchers made a new algorithm for enabling a single robotic unmanned aerial vehicle to herd a flock of birds away from a designated airspace. This novel approach allows a single autonomous quadrotor drone to herd an entire flock of birds away without breaking their formation.
Professor David Hyunchul Shim at KAIST in collaboration with Professor Soon-Jo Chung of Caltech and Professor Aditya Paranjape of Imperial College London investigated the problem of diverting a flock of birds away from a prescribed area, such as an airport, using a robotic UVA. A novel boundary control strategy called the m-waypoint algorithm was introduced for enabling a single pursuer UAV to safely herd the flock without fragmenting it.
The team developed the herding algorithm on the basis of macroscopic properties of the flocking model and the response of the flock. They tested their robotic autonomous drone by successfully shepherding an entire flock of birds out of a designated airspace near KAIST’s campus in Daejeon, South Korea. This study is published in IEEE Transactions on Robotics.
“It is quite interesting, and even awe-inspiring, to monitor how birds react to threats and collectively behave against threatening objects through the flock. We made careful observations of flock dynamics and interactions between flocks and the pursuer. This allowed us to create a new herding algorithm for ideal flight paths for incoming drones to move the flock away from a protected airspace,” said Professor Shim, who leads the Unmanned Systems Research Group at KAIST.
Bird strikes can threaten the safety of airplanes and their passengers. Korean civil aircraft suffered more than 1,000 bird strikes between 2011 and 2016. In the US, 142,000 bird strikes destroyed 62 civilian airplanes, injured 279 people, and killed 25 between 1990 and 2013. In the UK in 2016, there were 1,835 confirmed bird strikes, about eight for every 10,000 flights. Bird and other wildlife collisions with aircraft cause well over 1.2 billion USD in damages to the aviation industry worldwide annually. In the worst case, Canadian geese knocked out both engines of a US Airway jet in January 2009. The flight had to make an emergency landing on the Hudson River.
Airports and researchers have continued to reduce the risk of bird strikes through a variety of methods. They scare birds away using predators such as falcons or loud noises from small cannons or guns. Some airports try to prevent birds from coming by ridding the surrounding areas of crops that birds eat and hide in.
However, birds are smart. “I was amazed with the birds’ capability to interact with flying objects. We thought that only birds of prey have a strong sense of maneuvering with the prey. But our observation of hundreds of migratory birds such as egrets and loons led us to reach the hypothesis that they all have similar levels of maneuvering with the flying objects. It will be very interesting to collaborate with ornithologists to study further with birds’ behaviors with aerial objects,” said Professor Shim. “Airports are trying to transform into smart airports. This algorithm will help improve safety for the aviation industry. In addition, this will also help control avian influenza that plagues farms nationwide every year,” he stressed.
For this study, two drones were deployed. One drone performed various types of maneuvers around the flocks as a pursuer of herding drone, while a surveillance drone hovered at a high altitude with a camera pointing down for recording the trajectories of the pursuer drone and the birds.
During the experiments on egrets, the birds made frequent visits to a hunting area nearby and a large number of egrets were found to return to their nests at sunset. During the time, the team attempted to fly the herding drone in various directions with respect to the flock.
The drone approached the flock from the side. When the birds noticed the drone, they diverted from their original paths and flew at a 45˚ angle to their right. When the birds noticed the drone while it was still far away, they adjusted their paths horizontally and made smaller changes in the vertical direction. In the second round of the experiment on loons, the drone flew almost parallel to the flight path of a flock of birds, starting from an initial position located just off the nominal flight path. The birds had a nominal flight speed that was considerably higher than that of the drone so the interaction took place over a relatively short period of time.
Professor Shim said, “I think we just completed the first step of the research. For the next step, more systems will be developed and integrated for bird detection, ranging, and automatic deployment of drones.” “Professor Chung at Caltech is a KAIST graduate. And his first student was Professor Paranjape who now teaches at Imperial. It is pretty interesting that this research was made by a KAIST faculty member, an alumnus, and his student on three different continents,” he said.
(Figure A. Case 1: drone approaches the herd with sufficient distance to induce horizontal deviation)
(Figure B. Case 2: drone approaches the herd abruptly to cause vertical deviation)
2018.08.23 View 8915 -
Aerial Vehicle Flying Freely with Independently Controlled Main Wings
Professor Dongsoo Har and his team in Cho Chun Shik Graduate School of Green Transportation in KAIST lately developed an aerial vehicle that is able to control the main wings separately and independently.
Aerial vehicles in a typical category have main wings fixed to the body (fuselage) in an integrated form. Shape of main wings, namely airfoil, produces lift force, thanks to aerodynamic interaction with air, and achieves commensurate energy efficiency. Yet, it is difficult for them to make agile movements due to the large turn radius. Banking the aerial vehicle that accounts for eventual turn comes from the adjustment of small ailerons mounted on the trailing edge of the wings.
Aerial vehicles in another typical category gain thrust power by rotating multiple propellers. They can make agile movements by changing speed of motors rotating the propellers. For instance, pitch(movement up and down along vertical axis) down for moving forward with quadcopters is executed by increased speed of two rear rotors and unchanged or decreased speed of two front rotors. Rotor represents revolving part of motor. However, they are even less energy-efficient, owing to the absence of lift force created by wings.
Taking these technical issues of existing types of aerial vehicles into account, his team designed the main wings of the aerial vehicle to be controlled separately and independently. Their aerial vehicle (named Nsphere drone) executing all the thinkable flight modes, pitch/yaw(twisting or rotating around a vertical axis)/roll(turning over on a horizontal axis), is sketched in Figure 1 and actual flight of the aerial vehicle carrying out all possible types of flight modes is shown in Figure 2. Nsphere drone facilitates controlling the tilting angles of main wings and thus the direction of thrust power created by motors on the leading edge of main wings. Additional motor at the tail of Nsphere drone provides extra lifting force when trying vertical take-off and offers extra thrust power, by tilting the motor upward, while flying forward. Nsphere drone can change flight mode in the air from vertical to horizontal and vice versa. Due to the ability in rotating wings as well as changing the direction of thrust power come by the tail motor, the Nsphere drone with independently controlled wings can take off and land vertically without runway and auxiliary equipment.
Someone might say that it is similar to aerial vehicles that have tilt rotors attached to fixed wings for vertical take-off and landing. However, advantage of Nsphere drone is the ability in tilting each main wing entirely, thereby changing angle of attack of each wing. Angle of attack indicates the angle between the oncoming air or relative wind and a reference line on the aerial vehicle or wing. In general, lift force is affected by the angle of attack. Therefore, Nsphere drone can freely control the amount of lift force gained by each wing. This allows agile movements of Nsphere drone in the horizontal flight mode. Nsphere drone can fly like a copter type aerial vehicle in the vertical flight mode, and like a fixed-wing type aerial vehicle in the horizontal flight mode.
The trial to separate main wings entirely from the fuselage is very challenging. The separation of the main wings is realized by using supports that hold the main wings. One support penetrates both wings and two separate supports grab wings individually. It is also possible to apply this technology to large size aerial vehicle by including the fuselage as a part of the support for tilting wings. Part of the fuselage can be redesigned and integrated with main wings, taking plug-in structure to be coupled to the main fuselage and to stand thrust and air pressure.
Figure 1. Flight modes with independently controlled wings
Figure 2. Aerial vehicle with independently controlled wings demonstrates the capability in executing vertical and horizontal flight modes, as well as vertical take-off and landing.
Nsphere drone controls each wing independently according to target flight mode. The output of the control is sensed by sensors installed in Nsphere drone and undergoes an adjustment process until desired flight operation is achieved. Through this operational process, the Nsphere drone can make agile movements in ways that might not be attained by other aerial vehicles.
The team expects that the Nsphere drone, which is able to acquire energy efficiency, swiftness and speed, can be adopted for short and mid-distance air traffic delivery. Particularly, it can be distributed like the flying taxi announced by Uber and NASA in November 2017 and it can be effectively used for logistics delivery services such http:// as Amazon’s Prime Air.
Professor Har said, “Nsphere drone can be used for various fields, including airway transportation, military aerial vehicles, surveillance, general safety management, and logistics delivery services. Separate and independent control of the main wings gives us the chance to employ diverse and effective flying methods. Imagine a jet fighter that is able to evade a missile by the separate control of main wings http://. Just a bit of control could be enough for evading. Our flight mechanism is valid across the range of flight speed”.
At the beginning of the design process in 2016, his team filed patents to countries including Korea, U.S., and China, on various implementation methods, including plug-in structure coupled to the main fuselage, for separate and independent control of main wings.
Click the image to watch the clip of Nsphere Drone
2018.01.12 View 6166