An Inchworm-inspired Crawling Robot

This paper introduces the design and fabrication of a crawling soft robot controlled by a Shape Memory Alloy (SMA) wire. The robotic smart structure was inspired by the inchworm’s abdominal contractions during locomotion. The SMA wires were embedded longitudinally in the robotic body to imitate the inchworm’s longitudinal muscle fibers that are used to control the inchworm’s abdominal contractions. A ratchet structure was used to imitate the inchworm’s feet and provided friction with the ground during moving. Based on the resistor self-feedback of the SMA wire, we proposed an adaptive control strategy to avoid overheating. Experiments were conducted to evaluate the robotic locomotive performance for crawling, avoiding an obstacle, and the effect of the adaptive control strategy. The maximum speed of the robot was 48 mm·min⁻¹, and the SMA wire’s temperature was kept below 69 °C to prevent overheating. Those results show that this robot is with the ability to adapt to different environments.