Soft Robotics

This week we will explore the field of soft robotics. Learn about robots that have no rigid parts, can be actuated with air or liquids, and even self construct.

Papers to Read

There will be a discussion surrounding these papers on Saturday, July 22nd at 8:00 PM PST and Sunday, July 23rd at 9:00 AM PST. Please join the discussion in the #soft_robotics channel.

Soft Robotics: A Perspective—Current Trends and Prospects for the Future

Majidi Carmel

Abstract - Soft robots are primarily composed of easily deformable matter such as fluids, gels, and elastomers that match the elastic and rheological properties of biological tissue and organs. Like an octopus squeezing through a narrow opening or a caterpillar rolling through uneven terrain, a soft robot must adapt its shape and locomotion strategy for a broad range of tasks, obstacles, and environmental conditions. This emerging class of elastically soft, versatile, and biologically inspired machines represents an exciting and highly interdisciplinary paradigm in engineering that could revolutionize the role of robotics in healthcare, field exploration, and cooperative human assistance.

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A Resilient, Untethered Soft Robot

Michael T. Tolley et. al

Abstract - A pneumatically powered, fully untethered mobile soft robot is described. Composites consisting of silicone elastomer, polyaramid fabric, and hollow glass microspheres were used to fabricate a sufficiently large soft robot to carry the miniature air compressors, battery, valves, and controller needed for autonomous operation. Fabrication techniques were developed to mold a 0.65-meter-long soft body with modified Pneu-Net actuators capable of operating at the elevated pressures (up to 138 kPa) required to actuate the legs of the robot and hold payloads of up to 8 kg. The soft robot is safe to interact with during operation, and its silicone body is innately resilient to a variety of adverse environmental conditions including snow, puddles of water, direct (albeit limited) exposure to flames, and the crushing force of being run over by an automobile.

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Design, fabrication and control of soft robots

Daniela Rus and Michael T. Tolley

Abstract - Conventionally, engineers have employed rigid materials to fabricate precise, predictable robotic systems, which are easily modeled as rigid members connected at discrete joints. Natural systems, however, often match or exceed the performance of robotic systems with deformable bodies. Cephalopods, for example, achieve amazing feats of manipulation and locomotion without a skeleton; even vertebrates like humans achieve dynamic gaits by storing elastic energy in their compliant bones and soft tissues. Inspired by nature, engineers have begun to explore the design and control of soft-bodied robots composed of compliant materials. This Review discusses recent developments in the emerging field of soft robotics.

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A Hybrid Combining Hard and Soft Robots

Adam A. Stokes

Abstract - This article describes a hybrid robotic system combining hard and soft subsystems. This hybrid comprises a wheeled robot (an iRobot Create; hard) and a four-legged quadruped (soft). It is capable (using a simple, wireless control system) of rapid locomotion over flat terrain (using the wheeled hard robot) and of gripping and retrieving an object (using the independent locomotive capabilities of the soft robot). The utility of this system is demonstrated by performing a mission requiring the capabilities of both components: retrieving an object (iPod Nano) from the center of a room. This class of robot—hybrids comprising hard and soft systems functioning synergistically—is capable of performing tasks that neither can do alone. In contrast to specialized hard robotic arms with grippers (capable of performing some of the functions we describe here), which are complex, relatively expensive, and require sophisticated controls, this hybrid system is easy to construct, simple to control, and low in cost. The soft robotic system in the hybrid is lightweight, disposable if contaminated or damaged, and capable of multiple functions.

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An Untethered Miniature Origami Robot that Self-folds, Walks, Swims, and Degrades

Daniela Rus et. al

Abstract - A miniature robotic device that can fold-up on the spot, accomplish tasks, and disappear by degradation into the environment promises a range of medical applications but has so far been a challenge in engineering. This work presents a sheet that can self-fold into a functional 3D robot, actuate immediately for untethered walking and swimming, and subsequently dissolve in liquid. The developed sheet weighs 0.31 g, spans 1.7 cm square in size, features a cubic neodymium magnet, and can be thermally activated to self-fold. Since the robot has asymmetric body balance along the sagittal axis, the robot can walk at a speed of 3.8 body-length/s being remotely controlled by an alternating external magnetic field. We further show that the robot is capable of conducting basic tasks and behaviors, including swimming, delivering/carrying blocks, climbing a slope, and digging. The developed models include an acetone-degradable version, which allows the entire robot’s body to vanish in a liquid. We thus experimentally demonstrate the complete life cycle of our robot: self-folding, actuation, and degrading.

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Videos to Watch

Soft Robotics Inc.

Joshua Lessing, Director of Research and Development

Josh joined Soft Robotics Inc. after working as a postdoctoral fellow in the laboratory of Prof. Whitesides at Harvard University. As the Senior Scientist at SRI, Josh is responsible for the design and fabrication of a fundamentally new class of chemically inspired robotic actuators. He holds a Sc.B. in Chemistry from Brown University and a Ph.D. in Physical Chemistry from the Massachusetts Institute of Technology. His unique perspective on robotics has allowed for the creation of soft and adaptive robotic actuators through a novel combination of materials and fabrication methods.

Rajat Mishra

PhD Candidate, National University of Singapore

Rajat is currently a PhD candidate, developing control and mission planning algorithms for Autonomous Underwater Vehicles (AUVs) and also experimenting the application of soft bodied robots. He was also one of the developers of Humanoid iZac, which got national acclaim in India for its flexible motions. Additionally, he has worked on projects which required skills like Artificial Intelligence, Embedded Systems and Image Processing. Prior to becoming a PhD candidate, he was briefly working as an R&D consultant for developing medical devices, funded by NIH.

You can download the podcast here.

Projects to Work on

Project 1: Build a soft robot earthworm

You have seen several soft robots in action and have even heard from some of the folks in the field, but now it is time to build your own soft robot!

Inspiration for this robot comes from a YouTube member named Xyzaiden who has built a lot of soft robots in the past.

To make this earthworm robot you will need:

Two (2) large syringes (60 CCs are recommended) without the needle
1/8" Plastic tubing
1/2" Braided expandable tubing
2 Latex long balloons (the type you make balloon animals with)
Two (2) 5/16-Inch by 18-Inch Nylon Insert Lock Nuts

You will also need the following tools:

Duct tape or electrical tape
Scissors
A lighter

Steps

1 . Insert the tubing into the syringes. You only need about 3-6 inches of typing per syringe.

2 . Slide the nylon lock nuts onto the expandable braided sleeving. You may need to burn the ends of the nylon a little bit to keep it from splitting apart at the ends, but make sure you don't close it because the balloon still needs to fit inside the sleeving.

3 . Next, insert the balloon into the sleeving with the open-side of the balloon facing outwards. To insert the balloon is a bit tricky, but the best approach is to condense the sleeving, push the tip of the balloon as far into the sleeving as possible and repeat this pattern more or less. Focus on the tip of the balloon and the rest of the balloon will follow.

4 . After that, insert the tubing into the balloons and secure the ends with tape to prevent the balloon from falling off when being inflated. Slide down the nylon lock nuts to hold the tubing in place with added pressure. The final product should look as below.

That's it! You now have a soft robot that is made with inexpensive parts. When you inject air into one-side of the robot, this side will compress, moving the robot in the direction of the syringe used. While that side is still compressed, compress the other side of the robot, this will move the body towards the other syringe. Now, deflate the balloon of the first syringe expanding the body. Finally, relax the other side of the syringe. Repeat this motion and you can make your robot (very, very slowly) walk across the surface.

Project 2 Build your own "Metamaterial"

Introduction

As we saw earlier with Oribotics, materials that fold, bend or compress can change a robots capabilities. For this lab, you are going to make your own "metamaterial" out of ordinary paper. Miura-ori is a tessellation pattern that compresses and preserves its shape. When deformities are introduced, these can either strength or weaken the material under certain types of compression.

Creating a Miura-ori Pattern

The template for the Miura-ori pattern can be found here

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