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Engineers Have Created A High-Speed Multitask Soft Robot

Engineers Have Created A High-Speed Multitask Soft Robot

American engineers have developed soft pneumatic actuators for fully soft robots and based on them created a Multitask Soft Robot that can move faster than real jellyfish. The design uses pre-deformed elements, due to the stress in which the actuators can quickly change their shape under the influence of compressed air and switch between stable States. The article is available in the journal Advanced Materials Technologies.

Soft robots created from completely soft materials have long attracted the attention of engineers and scientists. Such devices can be useful where safe interaction with the environment or a person is required, for example, in medicine. The mobility of fully soft robots is usually based on stretching, compressing, bending, and twisting. Their actuators are made of soft elastic materials, and they are actuated using Pneumatics or hydraulics.

The study's lead author, Yining Chi, and his colleagues at the University of North Carolina and temple University have developed an advanced pneumatic actuator for soft robots. Their new work was a continuation of a previous project in which engineers created a robot based on a soft actuator with a bistable spine with a spring so that it could move at a gallop.

As part of the new research, engineers built actuators in two forms: in the form of a short tape and a disk. Each of these devices consists of layers of elastomeric material (Ecoflex silicone). The lower layer was subjected to preliminary stretching: the tapes were stretched along a long dimension, and the disks were stretched radially. As a result, the tapes became arched, while the disks took the form of a dome. At the next stage, the stretched layer was bonded with an undeformed layer of the same material, inside which air channels pass. Due to mechanical stresses in the lower stretched layer, the entire resulting structure was deformed, maintaining this stable state.

Under the influence of compressed air supplied through air channels, the actuator changes shape, and the final result depends on the ratio of the thickness of the layers: in the case when the thickness of the pre-deformed layer exceeds the thickness of the undeformed one, there is an increase in the existing bend, and the reverse ratio leads to a deviation of the actuator in the opposite direction. Also, the direction and value of the final deviation are affected by the amount of pre-deformation of the first layer and the value of the pressure of the injected air.

Depending on the conditions listed above, the developers have identified two modes of operation of the actuator: in the first case, the shape changes under the action of the supplied compressed air, followed by a return to the original state, and in the second — switching between two bistable States.

To demonstrate the capabilities of the developed devices, engineers have created prototypes of robots: Multitask Soft Robot and robot sonic. As it turned out, robots based on new actuators that imitate the movements of jellyfish and caterpillars are faster than similar structures that were created earlier using other technologies, as well as some types of real jellyfish and caterpillars. For example, the Multitask Soft Robot in the study was able to develop a speed of 53 millimeters per second, which is about twice the speed that the jellyfish Mitrocoma Cellylaria and Philalidium Gregarium develop (about 25 millimeters per second) at the same rate of body contractions.

The engineers also created a soft manipulator consisting of fingers fixed in the holder. In order to open the manipulator, it is necessary to supply air to the actuators, but it is able to hold the load without additional energy costs, only due to its own pre-deformation of the actuators.

This is not the first time that robot creators have been inspired by the movements of Medusa. For example, in one of our previous notes, we already talked about how German engineers created a Multitask Soft Robot controlled by a magnetic field. It is able to grab objects with its tentacles and dig holes in the bottom.