Nickel-Titanium SMA Springs Actuated Bioinspired Soft Robot for Pipeline Inspections

Soft continuum system-based robots which can interact with different environment are becoming a novel mechatronic system in varied fields. Many soft continuum robot can easily crawl, roll, steer, and climb. These innovatively designed systems are safe, effective and easy to control. In this study, two different soft continuum robotic prototypes are developed for locomotion in pipeline inspections. The motions of these soft robots were inspired from the locomotion behavior of the caterpillar. Unlike other types of soft robotic systems, the developed soft robots do not rely on pneumatic or hydraulic actuators, but can be operated electrically using nickel-titanium (NiTi)-based shape memory alloy (SMA) springs. These soft robot systems are fabricated via casting process using silicone elastomers. The linear locomotion profile of the soft robots are investigated carefully. Prismatic and tubular forms are used for designing of the soft robots to move within the pipelines via actuation of the NiTi shape memory alloy springs. The soft body of the robot systems are made of RTV-2 grade silicone rubber due to its hyperelastic response. A thermo-mechanical training process is applied on the NiTi SMA springs for achieving the linear motion inside of the silicone-based body. A microprocessor is used for creating the locomotion sequence of the soft robotic system. The periodic optimal locomotion sequence of the soft robots is determined by means of experimental investigations.