With the rapid development of flexible robots, people are more and more aware that cold, rigid is only our stereotype of robots. Recently, the internationally renowned journal Soft Robotics published the work of the team of Professors of Cold Jinsong, Harbin University of Technology, and Professor Norman M. Haveley of the University of Maryland, USA, entitled “The New Bending and Helical Extensile/Contractile Artificial Artificial Muscle Force Sauered By Elephant(a new curved spiral inspired by the elephant nose that stretches/shrinks pneumatic artificial muscles).
Inspired by elephant noses, the team developed a new type of flexible robot based on pneumatic artificial muscles (pneumatic muscles, PAMs).
In this study, “pneumatic artificial muscles” were a core element.
Pneumatic artificial muscles are a type of artificial muscle. Artificial muscle, or electroactive polymer, is a new type of intelligent polymer material, according to biological principles by proline, proline and glycine these three amino acids in a certain order of composition, can be applied under the electric field through the internal structure of changes to stretch, bend, tighten or expand, very close to the muscle fibers of living organisms.
Pneumatic artificial muscles, literally understood to be, are artificial muscles driven by external compressed air push and pull movements, with the advantages of softness, lightness, greenness and so on. This material is light in weight (minimum is only 10g), but it can provide a lot of power, with “four or two kilos” to describe it can not be more appropriate.
In fact, pneumatic artificial muscles have been widely used in software bionic robots, rigidity hydrostatic bones and other fields due to their bionic braiding structure, which is similar to biological muscle fibers and similar characteristics to skeletal muscles. In addition, these materials play an important role in medicine, robotics, military, aerospace, optics and other fields, with great commercial potential.
Researchers began studying this field as early as the 1940s. In July 2019, the MIT team also published a paper in Science about their new artificial muscles, which use two polymer-based polymer materials with different coefficients of thermal expansion, high density polyethylene and cyclolefin copolymer elasticity, which, once heated, can be freely retracted and lifted 650 times heavier than their own. The study also appeared on the cover of Science.
Pneumatic artificial muscles Source Baidu Encyclopedia
“Image nose” flexible robot
In recent years, many research teams have been inspired by petals, falcons, snakes, pigeons, fish, rabbits and so on, to design a variety of forms of flexible robots. The team was inspired by the elephant nose to design a new type of flexible robot.
The team points out that pneumatic artificial muscle movement is limited to a limited amount of single-axis contraction and stretching, which also limits its development.
To this end, the team designed a new type of curved spiral to stretch/shrink pneumatic artificial muscles (HE-PAMs/HC-PAMs) based on pneumatic artificial muscles that can be stretched/contracted.
According to the paper, HE-PAMs/HC-PAMs consist mainly of end fittings, elastic tubes, braided tubes and embedded flexible frames (see below).
When HE-PAMs/HC-PAMs expand, they produce a curved, rotating motion around the shaft, causing the actuator to spiral, similar to the elephant nose bending rotation process we’ve seen in zoos.
The distinction between stretching and contraction depends largely on the “weaving angle” – HE-PAMs at 54.74 degrees (i below) and HC-PAMs at weaving angles of 54.74 degrees (below ii).
On this basis, the team explored the potential applications of HE-PAMs/HC-PAMs in the field of flexible robots through a high degree of freedom flexible arm of a similar image nose. The researchers say HC-PAMs are highly loaded and he-PAMs can produce more deformations.
It is worth mentioning that this study proposes a unified theoretical approach that will provide a reliable reference to other researchers, who have developed a broad bending behavior model of pneumatic artificial muscles through experiments and analysis, and have studied the properties of axial, curved and spiral pneumatic artificial muscles within the same theoretical framework.
It is understood that axial, bending and spiral pneumatic artificial muscles can be widely used in all directions, such as software classification robots, search robots, biological robots, motion-assisted exoskeleton, force feedback wearables and so on.
Flexible robots to enhance human-machine interactivity
In fact, artificial muscle materials have become the forefront and hot topic of today’s research, which is closely related to the growing concern in the field of flexible robots.
100 years ago, the Czechoslovak writer Karel Chapek coined the word “robot” in his science fiction novels, based on Robota (Czech “labour, hard work”) and Robotnik (Polish “worker”). After 100 years, robots are no longer just rigid, icy machines, flexible robots are entering our field of vision, and industrial flexible robots and bioflexiblt robots are the two main branches.
Flexible robots can have features such as material softness, excellent environmental adaptability, superior safety, and good human-machine interactivity. As Wang Wei, Dean of the Institute of Robotics of the Hong Kong University of Science and Technology and Professor of Mechanical and Aerospace Engineering, said at the 2018 World Robotics Congress:
Compared with rigid body materials, soft materials are much more interactive, if the use of soft materials to make new robots, may open up new applications.
However, there are many technical challenges to perfectly combine these characteristics, and researchers are now looking for a breakthrough, such as Liu Jing, a researcher at the Institute of Science and Technology at the Chinese Academy of Sciences and a professor at Tsinghua University, who considered the application of room temperature liquid metals in flexible robots; , hydraulically driven way to drive the robot movement.
Although the field of flexible robot is still more “conceptualized” at this stage, its application prospects are extensive, and the future will bring about new changes.
About the author
The paper is written by Professor Cold Jinsong, A Ph.D. tutor at the Institute of Composites and Structures of Harbin University of Technology’s School of Aerospace.
Photo Source Baidu Encyclopedia
Since 1992, Professor Cold Jinsong has been conducting research on intelligent material systems and structures at KST, focusing on intelligent material systems and structural systems, fiber optic sensors, structural health monitoring, composite structural design and process technology, variable wing aircraft, structural vibration active control, fiber optic communication and microwave optoelectronics, Micro-electromechanical systems and so on.
In addition, Professor Leng Jinsong is the editor-in-chief of International Journal of Smart and Nano Materials, and has worked at Smart Materials and Journal of Associate Editor of international magazines such as Intelligent Material Systems and Structures. In 2006, he was selected to the Ministry of Education’s New Century Talent Program, in 2007 he was selected as a Distinguished Professor of Changjiang Scholars, and in 2018 he was elected a Foreign Fellow of the Department of Physics and Engineering of the European Academy of Sciences(Members of the Academy of Sciences).