Design and fabrication of a crawling robot based on a soft actuator

Inspired by biological systems, soft crawling robots provide unique advantages in terms of resilience and adaptive shaping during robotic motion. However, soft robots actuated by motors and pumps are usually heavy, noisy and bulky. In this paper, based on the principle of liquid-vapor changes of ethanol, a novel soft crawling robot that demonstrates more silent actuation and lighter weight compared with other robots is proposed. To increase the crawling speed of the robot, silicone mixed with liquid metal with a volume ratio of 20% is used to fabricate the actuators. The deformation of the actuator is analyzed and can be predicted using a theoretical model. To obtain effective crawling performance, a crawling locomotion sequence consisting of the three different parts (central, head and tail) based on the variable friction mechanism of actuators B and C is presented. The experimental results demonstrate that the robot can achieve forward movement on a horizontal surface and along vertical pipes and sticks. This study will provide further inspiration and guidance for the future development of crawling robots.