Preliminary mechanical analysis of an improved amphibious spherical father robot

Amphibious micro-robots are being developed for complicated missions in limited spaces found in complex underwater environments. Therefore, compact structures able to perform multiple functions are required. The robots must have high velocities, long cruising times, and large load capacities. It is difficult to meet all these requirements using a conventional underwater micro-robot, so we previously proposed an amphibious spherical father–son robot system that includes several micro-robots as son robots and an amphibious spherical robot as a father robot. Our father robot was designed to carry and power the son robots. This paper discusses improvements to the structure and mechanism of the father robot, which was designed to have a spherical body with four legs. Based on recent experiments in different environments, we have improved the father robot by adding four passive wheels, and we have redesigned its structure by means of three-dimensional printing technology, resulting in greatly improved velocity and stability. Moreover, due to the complexity and uncertainty of many underwater environments, it is essential for the father robot to have adequate structural strength. We analyzed the movement mechanisms and structural strength using finite element analysis to obtain the deformation and equivalent stress distributions of the improved robot. The results provide support for further analysis of the structural strength and optimal design of our amphibious spherical father robot.