Utilizing Bioinspired Soft Modular Appendages for Grasping and Locomotion in Multi-Legged Robots on Ground and Underwater

Soft robots can adapt to their environments, which makes them suitable for deploying in disaster areas and agricultural fields, where their mobility is constrained by complex terrain. One of the main challenges in developing soft terrestrial robots is that the robot must be soft enough to adapt to its environment, but also rigid enough to exert adequate force on the ground to locomote. In this letter, we report a pneumatically driven, soft modular appendage made of silicone for a terrestrial robot capable of generating specific mechanical movement to locomote in the desired direction. We used Finite Element Analysis (FEA) simulations to assess the soft leg's bending behavior, validated against the physical leg. In addition, we performed blocked force analysis to understand its force generation capabilities. We developed a soft-rigid-bodied tethered robot prototype and tested it on ground and underwater environments to evaluate its locomotion performance. The robot demonstrated successful forward and backward movement as well as left and right turns, both on the ground and underwater. We explored the object manipulation and transportation capability of the robot by adding two additional soft appendages as a gripper. The robot demonstrated its ability to effectively manipulate and transport objects of varying nature, including rigid items such as a 3D-printed plastic box and fragile objects like an egg. The maximum load-carrying capacity of the robot was also investigated both on the ground and aquatic medium. Our design approach provides a straightforward, cost-effective, and efficient method for creating versatile soft appendages for a robot that is capable of terradynamic locomotion. This approach showcases its potential applicability in underwater search and rescue missions.