My overarching research vision is to create computational material robots -- robots with advanced functionality through the algorithmic design of their material properties.
Robotics is traditionally the combination of three fields: mechanical engineering, computer science and electrical engineering. Recently, there has been more of a push to add a fourth field to the mix, material science, creating new material robots that use the embedded intelligence within their material properties to create new techniques. My goal is to create customizable computational material robotics so that given a task, robots can be autonomously designed, optimized and fabricated for any application.
In this vein, I have been primarily focused on soft robotic manipulators, creating new actuators and sensor integration with the potential for computational optimization and mass-customizable production.
This work introduces a new kind of metamaterial called handed shearing auxetics (HSAs). Auxetic materials are those with a negative Poisson's ratio, meaning that they expand perpendicularly when pulled in tension (unlike most materials which contract when pulled). Shearing auxetics expand with a bias rather than just isotropically expanding. By adding chirality to a shearing auxetic pattern, we can create new structures that have a strong coupling between twisting and extension, as well as structures with selective stiffness based on the pairing of chirality. We have demonstrated the potential of HSAs by using it to create a compliant linear actuator and as a soft robotic manipulator without the need for pneumatic actuation.
Published in Science, DOI: 10.1126/science.aar4586Abstract: In nature, repeated base units produce handed structures that selectively bond to make rigid or compliant materials. Auxetic tilings are scale-independent frameworks made from repeated unit cells that expand under tension. We discovered how to produce handedness in auxetic unit cells that shear as they expand by changing the symmetries and alignments of auxetic tilings. Using the symmetry and alignment rules that we developed, we made handed shearing auxetics that tile planes, cylinders, and spheres. By compositing the handed shearing auxetics in a manner inspired by keratin and collagen, we produce both compliant structures that expand while twisting and deployable structures that can rigidly lock. This work opens up new possibilities in designing chemical frameworks, medical devices like stents, robotic systems, and deployable engineering structures.
Published in 2018 IEEE-RAS International Conference on Soft Robotics (RoboSoft), 2018.
Abstract: In this paper, we explore a new class of electric motor-driven compliant actuators based on handed shearing auxetic cylinders. This technique combines the benefits of compliant bodies from soft robotic actuators with the simplicity of direct coupling to electric motors. We demonstrate the effectiveness of this technique by creating linear actuators, a four degree-of-freedom robotic platform, and a soft robotic gripper. We compare the soft robotic gripper against a state of the art pneumatic soft gripper, finding similar grasping performance in a significantly smaller and more energy-efficient package.
I am currently working on building on this prior work about programmable viscoelastic materials for further applications.