A tortoise-inspired quadrupedal pneumatic soft robot that adapts to environments through shape change

Multi-terrain adaptation and landing capabilities pose substantial challenges for pneumatic bionic robots, particularly in crossing obstacles. This paper designs a turtle-inspired quadrupedal pneumatic soft crawling robot with four deformable bionic legs to mimic the structure and movement of turtle legs. Finite element software is used to design and optimize the wall thickness of the soft actuator. Experimental tests are conducted under different pressures to verify the bending capability of the upper leg (0-40 kPa) and lower leg (0-60 kPa). Four gait models of the robot are achieved by controlling the airflow in different chambers of four soft actuators. Then the corresponding test scenarios are established to confirm gait control effectiveness. The soft actuator is designed with adjusted gait overlap ratios (0, 0.25, 0.5, 0.75, 1), enabling the soft robot to overcome obstacles up to 25 mm in height, showcasing superior obstacle-crossing capabilities. In addition to moving straight (maximum speed: 0.41 BL s^-1) and turning on rigid surfaces (45° s^-1), the robot is capable of crawling on various complex terrains (cloth, sand, flat ground, and slope) as well as water planning. These characteristics make the robot suitable for a wide range of applications, such as search and rescue, exploration, and inspection. The robot's ability to traverse complex environments and its robust performance in various conditions highlight its potential for real-world deployment.