Session: 04-07: Novel Actuators

Paper Number: 111012

111012 - Soft Actuators From Flexible Auxetic Metamaterials and Shape Memory Alloys Springs 

Flexible materials and bioinspired design have enabled structurally reconfigurable soft robots characterized by adaptive, flexible interaction with unpredictable surroundings. Unlike traditional rigid metal-based robot systems with multiple joints, soft robots designed with elastic materials can be simpler and cheaper to manufacture and exhibit nonlinear behavior favorable for cooperation with humans. Soft robots have great potential for applications such as medical diagnostics and minimally invasive surgery, life search and rescue in emergency or hazardous environments, marine or space exploration, and assistive devices for people with musculoskeletal disorders. For the operation of soft robots, control strategies that use traditional actuators (pneumatic, hydraulic, and motor-based systems) or smart material actuators (electroactive polymers, shape memory alloys and polymers, and ferromagnetic elastomers) have been proposed and demonstrated. Despite the rapid increase in soft robot-related publications in the last decade, most research has focused on pneumatic/hydraulic actuation approaches. Soft actuators or artificial muscles that rely on hydraulic, pneumatic, or motor-based systems are usually composed of a deformable chamber. The global deformation of the actuator is induced by the change in volume or pressure of the inner chamber by the external input. Using the force applied to both ends of the actuator is the primary operating principle of most current soft actuators. This bladder-based approach inevitably widens the cross-section of the actuator while it deforms. This is a characteristic commonly found in most studies of soft robots or grippers that mimic human hands. In this research, I specifically aimed to develop a soft actuator that is free from the aforementioned issues by using the extraordinary properties of the auxetic metamaterials and shape memory alloy (SMA). I assume that only electrical input will be used to create the motion of the soft actuator. In the designed soft actuator, the SMA and the auxetic metamaterials play the roles of actuation and biasing spring, respectively, which enables the soft actuator to produce repetitive actuation displacements. To achieve a large stroke length in the finished actuator, I used SMA in the form of a helical spring. In addition, for the overall flexibility and elasticity of the soft actuator, I decided to 3D print the auxetic metamaterials using a flexible filament. As a result, I developed a soft actuator that does not use a pneumatic, hydraulic or motor-based system to actuate the soft actuator and exhibits a negative Poisson's ratio when deformed. This research presents a new structural approach that combines smart materials and auxetic structures to create soft actuator systems with novel kinematic performance. Ultimately, this could help to simplify the overall design and manufacturing process of existing soft robots with multiple tubes and internal chambers, including the mold production process.

Presenting Author: Janghoon Woo University of Minnesota Twin Cities

Presenting Author Biography: I am a third-year PhD candidate pursuing a PhD in the Department of Mechanical Engineering since the fall semester of 2020. I earned my undergraduate and master's degrees in Electrical and Electronic Engineering from Yonsei University. Before to the United States, I conducted research on wearable technology from the perspective of electronic materials in S. Korea. I am currently conducting research on soft robotics using smart materials such as shape memory alloys and auxetic structures at DAMSL.