Imagine a search and rescue situation where a robot combs through rubble to save a trapped individual or an agile robot is administered to detonate a bomb. The machines ideal for these types of scenarios are soft robots that can be built with a higher level of mobility at a much lower cost. Soft robots hold enormous potential to save lives and improve manufacturing, and the TU Department of Mechanical Engineering is adding this type of project to its current list of research initiatives.
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Just announced with an official start date of January 2020, a National Science Foundation Emerging Frontiers & Multidisciplinary Activities grant worth $1.9 million has been awarded to Associate Professor Joshua Schultz and his biological robotics team. The NSF funding is the largest award Schultz has received in his career as a principal investigator and will support efforts to improve the mobility and control of fabric-reinforced inflatable soft robots. When applying for the grant, Schultz recruited the expertise of materials scientist and TU Associate Professor of Mechanical Engineering Michael Keller. Schultz and Keller are teaming up with two co-principal investigators from Brigham Young University: Assistant Professor of Mechanical Engineering Marc Killpack and Assistant Professor of Computer Science David Wingate. Schultz said robots built at TU and soft robotics research underway at BYU will explore functions and capabilities that aren’t possible in traditional models. “Soft robots can bump, scrape and push against the world,” he explained. “They can accomplish tasks by running into a wall on purpose and then using the wall to support itself when it reaches for something.”
Autonomous robots
The concept of soft robotics also involves devices that can reach under a door to retrieve an item, entwine objects or squeeze into a small gap between a door that’s ajar. Soft robots can conform to features in an unknown environment and change shape, and when they collide with another object, neither the robot nor the other item is damaged. Equipping the device with smart technology allows it to detect that contact occurred and behave intelligently to complete the task. “We are trying to make these robots autonomous, so they can operate on their own without a human continuously issuing commands in real-time,” Schultz said. “Previous soft robots needed the ingenuity of a human to complete the tasks that the robot was doing. We will use new mathematical models, smart materials and sensors, and machine learning, so that robots can do the task autonomously without supervision by a human.”
The faculty plan to host graduate students at both TU and BYU to assist with the project and add a TU post-doctoral fellow to conduct research in kinematics and materials science. For the next four years, the group will focus on developing concise models for the motions of a fabric-reinforced rubber tube that can be evaluated quickly by a computer. Schultz described the device as an arm made of silicone. One side of the arm is made from a fabric similar to the canvas of a tent while the other is constructed of a more flexible material. The arm’s fabric can set up, bend, move and fold, but it won’t stretch. As the arm inflates, the stretchy side stretches but the fabric side will only bend. “As this robot is made, it can only trace out one path in space,” Schultz explained. “It can’t reach robotics workspace, but we want the robot to be pear, ring or cone in shape — we want it to have some volume in which it can reach everywhere inside its range of motion.”
Adapting to workspace with smart technology
Keller and Schultz are experimenting with materials that can be patched to the arm and communicate with a computer. By turning on one patch or a combination of patches at different times, the arm’s wall stiffness will change and expand its potential workspace. “The robot will be able to reach in some useful volume to do tasks, so that’s progress in the device functioning like a robot instead of just a conversation piece,” Schultz said.
Once the robot can reach a given volume, it must move to a specific spot within that space, so controlling movement and alleviating bounce from the stretchy material is key. Schultz and Keller hope to change the stiffness and inflation of the robot’s walls in a way that if it is bumped and begins to bounce, they can stop the interference and smoothly move it to pick up something or move against something. “Robotics is used in all kinds of industries, but the reason robots are limited in their application is because they can easily bump into something, and they lack dexterity to do a task,” Schultz explained.
Scientists and engineers have successfully demonstrated soft robotics designs in the past but adding the component of smart technology poses a challenge. Schultz said the elastomeric materials of soft robots allow for many sensors to be molded into the robot to measure touch, proximity and the shape of objects. If successful, the project will produce improved algorithms to process sensor inputs and enable the robot to distill them into meaningful information about itself and the world. Schultz said that while the designs they plan to develop are technologically advanced, they are financially feasible. “An industrial robot might cost upwards of $20,000, and you have to make a big purchase before you can find out if it suits your company’s needs,” he said. “Soft robots are more like disposable income — they’re made from pretty inexpensive materials.”
Overcoming challenges with soft robotics
Basic models developed by the team will present an algorithm that will configure a variety of possible shapes for the robot at each instant. Data gathered by the platforms will help the soft robot learn how to select the appropriate commands, which include the combinations of pneumatic valve signals and tunable stiffness patches in the rubber walls, to autonomously complete useful tasks where the robot must push on the environment.
“We want our robot to be able to overcome challenges like hanging drywall and reaching into clutter amongst trees, tall grass, rocks or debris to bend around anything in its path,” Schultz said.
To learn more about biological robotics at The University of Tulsa, please contact Professor Schultz at joshua-schultz@utulsa.edu.