Bio-inspired robot: Fly like a living being

My undergraduate major is computer science, especially in embedded systems, which means embedding chips, circuits or algorithms into almost all the electronic devices seen on the street, like vending machines or scrolling advertisement screens. But when I want to create a robot, I am stuck. I asked myself: why do we need a robot? I asked several friends majoring in different subjects either, and their answers are: I don't know, maybe help me to finish my work. But they truly don't want to be unemployed. So I set my sights on animals, plants and the environment. I mean, human science and technology are more and more advanced, while the living space of animals and plants is getting smaller and smaller and the environment is getting worse. I hope to know more about them and provide valuable help without disturbing their lives, which is actually also helping ourselves.

At present, the technology of unmanned aerial vehicles (UAV) is becoming mature, and it, along with mechanical arms and unmanned driving, has become a common carrier of robotics techniques. Drones for agriculture made by DJI can help people improve the efficiency of sowing and fertilizing with high performance. DJI Agras T40 can fly for 3-5 hours with remote control from 5 km away. Just like the one from DJI, drones can do lots of cool things for people but still not enough, right? The mechanical materials and computer algorithms alone can't make UAVs smart enough to integrate into the ecosystem. Imagine that: there is a bird, which can close contact with trees and other birds, and regularly feed back the perceived problems to us, acting like an emissary between animals and humans.[1] And this bird is our drone. It seems unrealistic, but if we broaden our views, we will find solutions hidden in other disciplines (not only computer science), and some pioneers have made initial achievements.

Introduction of agricultural drone, DJI Agras T40

Soft Body

Aircraft made of hard materials need to rely on a large number of complex control algorithms to complete steady flight, while aircraft made of soft materials with more flexible bodies can exploit principles of physics, like fluid dynamics to simplify these control logics to some extent.[4] Soft materials also make it possible for aircraft to have intelligent bodies. For example, rigid drones need infrared sensors to measure the distance to avoid a collision, while a soft drone can judge whether a collision occurs by detecting the deformation of the body, which is equivalent to covering the whole body with sensors. In addition, if we can make drones with soft materials, it means that some degradable and edible chemical materials, like Polylactic acid, can be used. This will enable robots to integrate into nature better.

A research group from the University of Bristol proposed a deformable motor and used it to drive a pair of insect-like flapping wings, which makes big progress.[3]

Fig 1. Flapping wings, driven by the deformable motor. Source from: Power optimization of a conical dielectric elastomer actuator for resonant robotic systems. Extreme Mechanics Letters, 35, [100619].

Biomimetic Robot

Festo, a technical company found in Germany, integrates new technologies and develops a series of bionic aerial robot prototypes, which are impressive. Their newly designed BionicSwift in 2021 imitates the plume of birds to drive the flight with less energy.

Fig2. Bionic aerial robots from Festo. From left to right are the Air_ray, AirPenguins, SmartBird, BionicOpter, eMotionButterflies and BionicFlyingFox.

BionicSwift designed by Festo

When learning from these fly experts, we can always find some compelling abilities they obtained. The BionicOpter's biological prototype, dragonflies, can fly at a high speed in nearly all directions and have excellent hovering and inverted flying skills. And birds can land quickly and stably, while large planes need a long buffer to stop. A group from Bio-Inspired Flight Lab in Bristol Robotics Laboratory (BRL) are investigating bird flight aerodynamics and trying to get bio-inspiration from those flying guys.

Inspiration from birds

Another potential advantage of biomimetic robots is that their appearance may help to get a closeup of creatures. And the flapping-wing flying mode will be quieter and less strange than traditional flying modes such as multi-rotors, which may cause less disturbance to creatures.

Bio-inspired Design

We probably intuitively think that bionics is to make robots look like and act like animals, but the biological system is too complicated to reproduce the complete mechanism of a living being, even if it's just a small fly. Therefore, it is more common for scientists only study a certain mechanism existing in nature to improve a certain aspect of robot performance. Moreover, these bionic studies can cover not only animals but also plants.

A bio-inspired design published by 'Science Robotics' introduces a samara-like drone.[2] It reduces the power consumption of the drone by using the principle that the biplane seeds gyrate when they fall. This design allows the drone to fly for ten to twenty minutes. For an aircraft with only 35.1 grams, this endurance time is amazing.

Samara-like aircraft

The above examples provide new ideas for creating robots integrated into the ecosystem from three different perspectives. I believe that combining knowledge from these interdisciplinary fields to empower robots with various abilities will make a big difference in the future, e.g. a robot with a soft body may achieve to gain tactile perception and a bionic appearance may be more acceptable to animals. Plus, it's also significant to endow robots with enough spatial intelligence, which means letting robots manage all their senses like animals or humans, make reasonable responses to external stimuli on their own and feedback on the world they experienced to us. Based on this, we can fabricate a better robot inspired by biology, and then use this robot to understand creatures and the environment more deeply, forming a virtuous circle.

There is still a long way to go and it is necessary to realize the importance of interdisciplinary cooperation: chemistry and materials science can help us find more suitable materials for making robots; Fluid dynamics and morphology can help us understand the mechanism of drones and optimize their performance based on robust theory; Biology and environmental science inspire us to create environment-friendly robots that can be integrated into the existing ecosystem; Computer science and electronic technology make robots have smarter brains, and soft robotics further enhance robots' bodies with multi-functions.

Reference

[1] B. Mazzolai, C. Laschi, A vision for future bioinspired and biohybrid robots. Sci. Robot. 5, eaba6893 (2020).

[2] Songnan Bai, Qingning He, Pakpong Chirarattananon, A bioinspired revolving-wing drone with passive attitude stability and efficient hovering flight. Sci. Robot. 7, eabg5913 (2022).

[3] Cao, C., Gao, X., Burgess, S. C., & Conn, A. T. Power optimization of a conical dielectric elastomer actuator for resonant robotic systems. Extreme Mechanics Letters, 35, [100619] (2020).

[4] Sareh, S., Siddall, R., Alhinai, T., Kovac, M. Bio-inspired Soft Aerial Robots: Adaptive Morphology for High-Performance Flight. In: Laschi, C., Rossiter, J., Iida, F., Cianchetti, M., Margheri, L. (eds) Soft Robotics: Trends, Applications and Challenges. Biosystems & Biorobotics, 17, 65-74 (2017).