Big data abstracts are reproduced with permission from the Robot Lecture Hall
Watch out for this mechanical insect showing off the latest flying stunts!
I saw it land smoothly on the vertical glass door, glide a little, and then take off easily.
The series of movements is light and silky, almost indistinguishable from the flight mode of a real insect!
After this video was posted on Douyin, netizens began to think about its future development and application:
Some people said: "I dare not think that if I cooperate with the swarm technology of the National Defense Science and Technology University, there will be many pieces of minework!" ”
Another netizen said: "You can study the southern cockroach, no matter which angle can go straight to the door." ”
This mechanical insect comes from Nanjing University of Aeronautics and Astronautics and is an "amphibious insect" that can crawl and fly.
Not only can it land and take off freely on glass, but even walls, wooden doors, marble, tree trunks, and even tents will not be able to defeat it:
And its advantage is not simply "climbing far" or "flying high", but the seamless connection between the two states, or on the vertical wall, which is an important ability that amphibious robots lack at present!
Imitate the "fly" + "climb" of insects
For cockroaches can fly, in addition to the scalp numbness when you think about it, it also shows the strong flight movement ability of insects.
Insects can not only flutter their wings, but also fly to various walls to attach and crawl, and the two states switch freely, providing scientists with an excellent bionic model.
Speaking of "flying", there are already a lot of flapping wing robots; When it comes to "climbing", wall-climbing robots are not few.
However, the combination of the two is a rather challenging subject, and the existing hovering flapping wing system is difficult to generate enough lift to support the wall-climbing robot; Wall-climbing robots that can attach crawls to multiple types of surfaces are not comprehensive enough, and existing bionic robots rarely have these sports capabilities at the same time.
Robots that can shuttle between the air and the wall belong to the "multi-modal movement of cross-domain robots", in order to achieve this, it is necessary to study a new conversion control method between "flying" and "climbing", which can not only improve the overall movement performance of amphibious machine insects, but also have great significance for understanding the take-off and landing of insects!
So what is the mystery of the body structure of insects?
The insect has a fairly flexible control over flapping its wings and body posture: when hovering, it flaps its wings to generate upward lift, while body posture can be changed arbitrarily. Especially when landing or taking off on a wall, it is necessary to complete a series of complex modular movements, including body slowing down and body rotation at large angles.
Inspired by this, researchers at Nanjing University of Aeronautics and Astronautics also incorporated this "large-angle rotation" into bionic robots.
Flapping wing hybrid layout
The mechanical insect adopts a hybrid flapping wing and rotor layout:
The appearance looks like a dragonfly, a pair of wings (flapping wings) are symmetrical on the horizontal axis, 2 rotors are under the head and tail, the wall-climbing rotors on the sides of the head resemble two large eyes, and the tail is a battery.
This hybrid layout provides stable attitude control for the robot:
- Head-tail rotor differential rotation - generates pitch moment, providing the robot insect with the control of pitch movement and longitudinal movement;
- Left and right flapping wing differential flutter - generate rolling torque, providing the robot insect with the control of rolling movement and lateral movement;
- The vector deflection servo drives the head rotor power pack to deflect, generating a heading deflection torque, which provides the control of the yaw movement for the robot insects.
The structure of the mechanical insect allows efficient and controlled flight, but the climbing part is different from the insect and is designed above the robot's body. The power of the robot when flying can provide aerodynamic negative pressure adsorption for the climbing part, and can also create synergistic effects with the crawling mechanism with biomimetic adhesion characteristics, while also resisting the overturning moment caused by gravity.
In order to better study the attitude of mechanical insects in both directions when flying and crawling, the researchers also performed kinematic and dynamic analysis.
Through analysis, they determined the attitude of the robot during flight by three Euler angles, which was related to the rotational angular rate of the robot in all directions, and analyzed the form that is prone to instability during the movement of the robot to determine the relationship between the adsorption force of the rotor negative pressure system and the parameters such as gravity and wall friction coefficient.
Coordinate control policies
To achieve fly-land-flight cross-domain movement on vertical walls, in addition to relying on a hybrid layout, a coordinated control strategy of actuators is required.
The transition plan is as follows:
- Flight - landing
The robot slows down and slowly approaches the wall, and when the adhesion pad at the front end touches the wall, it maintains flight stability, self-calibrates the pitch and roll attitude, gradually reduces the pitch angle, and stops flapping. When the pitch angle exceeds the critical angle, the expected pitch moment gradually decreases until it fully touches the wall.
- Landing - flying
The robot maintains the thrust of the rotor of the head so that it is in constant contact with the wall; reduce tail rotor power; When the pitch angle is judged to -60°, the flapping wing is automatically started; When subsequently leaving the wall, it is necessary to accurately control the pitch angle and angular velocity, and it is also necessary to enhance the tail rotor power in advance to restrain the gravity effect, and reduce the drop speed and pitch angle velocity to almost zero before the robot reaches a horizontal attitude, so that the robot enters a stable and controllable hover flight.
In these processes, it is important to have adequate air and wall control. Specifically, the hybrid of aerial wall-climbing robotic flapping wings and rotors must be able to provide enough torque on all 3 axes to achieve attitude control during flight and stability during wall climbing.
To verify whether the design parameters of the dynamics provide sufficient control, the researchers compared the effects of different control signal inputs on the robot's control ability.
Finally, the maximum time for the robotic insect to complete a continuous landing flight transition was 6.1 seconds. The fly-to-climb transition process took 0.40 ± 0.03 s, the climb-to-fly transition process took 0.70 ± 0.09 s, and the crawling speed on the vertical wall was 6 cm/s.
Not only that, but this method also improves the flight speed, and the maximum speed of outdoor flight of mechanical insects is 6.8 m/s!
Investigator profile
The study, published in the journal Research, is titled "An Aerial–Wall Robotic Insect That Can Land, Climb, and Take Off from Vertical Surfaces."
At the end of the article, the researchers believe that current mechanical insects still have shortcomings: for example, lack of control of climbing direction, large energy consumption when maintaining balance, etc.
In the future, the team will further optimize the layout design and improve the crawling mechanism and the control of the rotor on the direction of robot movement during the crawling stage. It will also increase the microscopic hook claws of robotic insects to achieve a crawling mechanism more similar to that of real insects.
In addition, in the future, it is also planned to supplement the navigation, perception, autonomous control and long-distance communication of robotic insects, use machine learning to optimize the power distribution of the fly-climbing conversion process, or autonomously detect, identify and track specific targets.
The corresponding author of the article: Ji Aihong, is currently a researcher and doctoral supervisor of Nanjing University of Aeronautics and Astronautics. The main research areas include: motion bionics and intelligent robots (mainly including medical robots, wall-climbing robots, flying robots, continuum robots, parallel mechanisms, cross-domain technology, etc.)
Another corresponding author: Zheng Xiangming, is currently a researcher and doctoral supervisor of Nanjing University of Aeronautics and Astronautics, mainly engaged in the overall design of aircraft and the design of new concept micro aircraft. He participated in the development of the mainland's first micro-small autonomous flight reconnaissance UAV and other types of aircraft, and won two first prizes for national defense science and technology progress.
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