Pneumatic soft actuators may not be a term often heard in everyday conversation, however more often than not, you’ve enjoyed their benefits. They use compressed air to generate movement, and when coupled with sensors, they’ve proved to be a vital support in many applications, including robotics, assistive wearables and rehabilitation technologies.
There’s an issue in the creation of these small, dynamic devices with advantages like high response times and high power-to-input ratios. They require manual design as well as a fabrication pipeline, which leads to lots testing and trial to determine whether the designs work.
Researchers from the MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) developed an scalable process that allows for the computational design and use of digital technology to create soft pneumatic actuators, dubbed “PneuAct.”
PneuAct utilizes a machine knitting process that is similar to the plastic needle your grandmother used for knitting, but this one operates on its own. A human designer can simply define the stitch and sensor patterns in software , which is used to program how the actuator moves and can be reproduced prior to printing. The piece of fabric is made using a knitting machine which is then fixed to an inexpensive off-the-shelf silicone tube to make the complete actuator.
The knitted actuator is equipped with the use of conductive yarn to sense it, which allows the actuators to “feel” what they touch. The team created a variety of prototypes, including an assistive glove as well as a soft hand, an interactivity robot as well as an e-quadrupedal walking pneumatic. Their prototypes, that through the use of yellow fabric, are a little like banana fingers, comprised an assistive glove as well as a soft hand. an interactivity robot as well as the pneumatic quadrupedal robot.
There’s been plenty of motion in the development of hardware for soft pneumatic actuators through the years — a prototype in 2019 of the collaborative robot made use of such actuators to replicate human-like gripping on its hands–the technology for design hasn’t advanced in the same way at the speed. Traditional processes usually use molding and polymers, however scientists employed a mixture of sensing and elastic stitches (with conductor yarn) which allows programming the bending of actuators as they expand and to incorporate feedback from the real world.
For instance, the group employed the actuators to create the robot which could sense when it was specifically touched by hands of humans and responded to the contact.
The glove of the team can be worn by a person to aid in the movement of fingers and reduce the amount of muscle work required to perform chores and actions. This holds many possibilities for people who have injuries, restricted mobility, or injuries to fingers. The technique could also be employed to construct an exoskeleton (wearable robotic devices controlled by a computer , which augment human movement and help bring back movement and mobility) For instance the researchers designed a sleeve to aid users to bend their knee, elbow or any other body part.
“Using digital machine knitting, which is a very common manufacturing method in today’s textile industry, enables ‘printing’ a design in one go, which makes it much more scalable,” says Yiyue Luo, MIT CSAIL Ph.D. student and lead writer of a paper on the research. “Soft pneumatic actuators are intrinsically compliant and flexible, and combined with intelligent materials, have become the backbone of many robots and assistive technologies–and rapid fabrication with our design tool can hopefully increase ease and ubiquity.”
Understanding sensors
One kind of sensing that which the team integrated as “resistive pressure sensing,” in which an actuator “sends” pressure. When creating an automated gripper such as a gripper, for instance when it grasps something it will detect how much force is exerted on it and will then try to determine if the grip succeeds or fails. The other kind of gripper is “capacitive sensing,” where the sensor detects information about the materials the actuator is into contact with.
The actuator is robust and no yarns were damaged during their research However, one drawback to this system was that it was restricted to tubes-shaped actuators since it’s very simple to purchase off the shelves. The next step would be investigating actuators with different shapes to avoid being restricted by one shape. Another possibility that scientists will investigate is extending the application to incorporate the task-driven, optimization-based design where users are able to define their desired poses and best stitch patterns that are generated automatically.
“Our application is quick and simple to use. It provides a clear and accurate preview of the designs of users which allows them to swiftly create virtual prototypes, and only having to create one time. But , the process is still some trial and error from humans. Could be a computer determine how textiles should be programmed into actuators in order to enable sophisticated, sensing-driven behaviors? This is the next frontier” Says Andrew Spielberg, a postdoctoral researcher with the Department of Materials Science and Mechanical Engineering at Harvard University.
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