Design of an Amphibious Spherical Robot Driven by Twin Eccentric Pendulums With Flywheel-Based Inertial Stabilization

This article presents the design of an amphibious spherical robot with a sole focus on its mechanical design to achieve high torque, versatile motion modes, compact and lightweight structure, and high stability and traction, without relying on optimal control strategies. To achieve this, we unified the use of twin eccentric pendulums for high torque, flywheels for inertial stabilization and enhanced traction, and flywheel brakes for instantaneous torque to overcome obstacles. Dynamic analysis is performed, which gives an insight into the robot's motion and helps in making design decisions. High-level and low-level design decisions are discussed based on robot dynamics and intuition. Finally, a prototype of the designed spherical robot is assembled, and subjected to performance evaluation through terrestrial and aquatic locomotion experiments. The experimental results validated our design decisions, showing the design approach yields a spherical robot with stable and versatile locomotion, building the foundation for further improvements via optimal control and sensing.