Researcher(s)
- Kyle McKee, Electrical Engineering, University of Notre Dame
Faculty Mentor(s)
- Nathan Lazarus, Electrical and Computer Engineering, University of Delaware
Abstract
Robots made of soft, flexible materials are more versatile and resilient than traditional robots due to their ability to change shape and absorb impact. Sensors and actuators are needed on any robot to detect its surroundings and interact with its environment. Many current soft robots achieve this using external pneumatic pumps that require the robot to be tethered. On-board stretchable strain sensors have been achieved using liquid metal coils. However, having different mechanisms for sensing and actuation complicates the fabrication process and clutters the robot. This project implements multi-functional liquid metal coils into a fully soft swimming robot for sensing and actuation. The inductor was created by injecting the liquid metal Eutectic Gallium Indium (EGaIn) into a coil of plastic tubing, attaching copper contacts on the ends, and embedding the coil in a block of silicone to simulate the soft robot’s structure. The coil’s strain sensing was characterized through uniaxial tensile tests. A 21.7% inductance increase could be seen with 100% strain. The coil’s actuation was characterized by deflecting a silicone fin with an embedded permanent magnet. Consistent contacts between solid wires and liquid metal are difficult to make, so a copper coil was used for this testing. A deflection of 49.25 degrees was seen when applying a current of 2 A. Two coils were embedded into a soft swimming robot propelled by an external pump. In the future, the coils will be able to determine the current robot state, detect external objects, and deflect the fins to provide steering control to the robot. Feedback and control will also be added to create a fully autonomous soft swimming robot capable of steering and object detection.