Recently, Professor Feng Wei of the School of Materials Science and Engineering of Tianjin University has developed a 4D printing soft robot with autonomous action ability and tactile strain. The robot has thermal unconstrained rolling ability after one printing and forming without any other subsequent processing procedures.
The research results were published in the top journal “Substance” under “Cell” Press.
Traditional manufacturing methods limit the “intelligence” of soft robots
Soft robots are a new type of flexible robots that can adapt to different unstructured environments and interact with humans better and more safely. Compared with traditional robots, they are flexible, adaptable and less dangerous. But at present, soft robots are mainly manufactured by manual assembly processes. The limitations of the manufacturing method cause production difficulties, limit the range of material selection, and it is difficult to obtain complex driving performance, especially unrestricted autonomous movement and perception capabilities.
In contrast, 3D printing (additive manufacturing technology) can automatically and accurately transform design ideas into complex parts based on digital models, thereby significantly improving production efficiency and manufacturing flexibility.
“On the basis of 3D printing, we add a’time’ dimension to the manufacturing of soft robots-that is, 4D printing, processing smart materials into dynamic structural materials that respond to thermal stimuli.” Feng Wei introduced that we hope to use 4D printing A smart soft robot with perception and adaptability can be obtained instead of an actuator that only deforms. If soft robots can have richer driving phenomena, they can imitate the behavior of more animals or people and realize intelligence, that is, artificial intelligence. Most of the current researches are based on bending and deforming actuators, which are only preliminary stimulus response performance.
4D printing directly obtains intelligent software robots
Obtaining intelligent software robots directly through 4D printing is a huge challenge.
Feng Wei’s team used 4D printing to accurately process liquid crystal elastomer smart materials, and directly obtained smart software robots with perception and adaptability. “Liquid crystal elastomer is a cross-linked polymer network that can connect anisotropic rigid mesogenic units in the polymer network. Its special structure organically combines the elasticity of rubber and the anisotropy of liquid crystals to produce Special optical and physical properties.” Feng Wei introduced that due to the directional arrangement of atoms in the crystal, the properties of the liquid crystal are different in all directions, which is anisotropy.
By transforming the 3D printer based on fused deposition technology, the team realized the precise ink direct writing printing technology of liquid crystal elastomer. In this process, the rigid mesogen unit is directly written into a three-dimensional structure with a controllable molecular sequence. Since the mesogen arrangement order is set through the printing path, different arrangement orders can achieve different stimulus response performance.
Feng Wei’s team obtained a 4D printed soft robot with autonomous action ability and tactile strain through the new phenomenon of thermal drive of liquid crystal elastomer. The robot has thermal unconstrained rolling ability after one printing and forming, without any other subsequent processing procedures, simple and fast production, and good repeatability.
“What surprises us most is the autonomy of this robot and its intelligent bionic behavior when encountering obstacles. The robot’s rolling is stable and powerful, and the speed and direction can be adjusted by changing the shape and size.” Feng Wei said.
When placed on a hot stage at 160°C, the 4D printed rectangular soft robot deforms into a spiral tube and automatically starts rolling on the heating plate. Adjusting the size can change the scroll speed of the robot. The direction of rolling is controlled by the direction of curvature of the spiral tube and can be easily changed. The entire driving process of this tubular robot is automatic, without changing environmental factors, and can complete tasks without manual control. Since the soft robot exhibits certain viscoelastic properties and considerable rolling driving force, it can still roll up even when placed on a tilted heating plate at a certain angle.
Can load 40 times the robot’s own weight
Compared with performing precise and repetitive tasks in daily environments, robots’ work in extreme environments is more irreplaceable. Performing intelligent and controlled tasks under conditions such as extreme heat, cold, radiation, deep water, vacuum and other conditions is extremely challenging for all types of robots. Compared with ordinary metal robots with rigid systems, soft robots have more limited working capabilities in extreme environments, especially under extreme high temperature conditions.
The current soft robots, especially those composed of a single material, have a long and difficult road to artificial intelligence.
The 4D printed soft robot developed by Feng Wei’s team this time, due to the characteristics of the spiral cylinder’s curvature direction controlling the rolling direction, makes this soft robot have tactile perception capabilities similar to insect antennae, and can detect obstacles on the road ahead. The realization of the level of surpassing or turning back, reflects a certain degree of intelligence from the perspective of behavior. For example, when the robot traverses an unknown fixed-length path, three scenarios can be realized: crossing within a predetermined time means that there are no obstacles in the rolling path; slower than the predetermined time means that the unknown path is slightly blocked; the robot returns to the starting point It means that the unknown path is severely or completely blocked.
In addition, cargo transportation is also an important application of unconstrained soft robots. “Although our robot can only move forward and backward, it can still be used for point-to-point cargo transportation.” Feng Wei said: “The hollow cylinder of the tubular robot provides loading space for linear objects. In order to test the tubular robot in Africa For the transportation ability of linear objects, we designed a small traction device similar to the cattle, the whole device can move at a constant speed on the heating plate. This shows that this kind of soft robot can be used to carry out cargo transportation in extremely high temperature environments Task.”
By increasing the length of the sample, the soft robot can significantly increase the transportation capacity. If the sample length is increased to the meter level, the transport capacity of the tubular robot may increase by an order of magnitude, and the maximum capacity of the loaded goods can reach 40 times the weight of the robot.
Source – https://bit.ly/2Xjnl7t