AMPHIBIOUS ROBOT WITH ROCKER-BOGIE MECHANISM AND A UNIFIED PROPULSION SYSTEM FOR MOTION ON RUGGED TERRAIN AND IN�WATER

Abstract

Amphibious animal locomotion gives excellent bioinspiration for developing locomotion mechanisms for amphibious robotic systems. Reconnaissance, environmental monitoring, and search and rescue operations on land and water demand an amphibious style of locomotion. However, amphibious locomotion is complex as it involves maneuvering on rough and uneven land terrain and in shallow water at the land-water interface. The present amphibious robots for ground environment locomotion, particularly on rough terrain, employing leg-based mechanisms, have lower speed while those that use wheel-based mechanisms have lower terrainability. Locomotion on both land and in water using the same propulsive mechanism could be able to reduce the burden of multiple propulsion systems. However, while transitioning between multiple environments, the composite mechanism requires an additional switching mechanism to switch between the modes, which, in turn, increases the complexity of the control architecture. Consequently, there is a need for a single unified mechanism-based locomotion of amphibious robots with higher terrainability and speed. This research developed an amphibious robot that employs a rocker-bogie mechanism that provides passive suspension for higher adaptability on rough land terrain, integrated with serrated paddle wheels for increased mobility and locomotion performance in the water environment. The maneuverability performance of the proposed model was simulated using ADAMS (Automated Dynamic Analysis of Mechanical Systems) and CFD (Computational Fluid Dynamics). The maneuverability on the ground environment is simulated on uneven terrains with some geometric profiles with obstacles in the ADAMS environment. Simulation using CFD achieved a 0.6 m/s speed of the paddle-wheel propulsors and maximum drag force of 0.0243 N across the paddle wheel. Experimental validation for the robot was performed on the benchmarked terrain for terrainability and mobility performance analysis. The results demonstrated that the amphibious robot with 6cm radius wheels successfully maneuvered over obstacles of 5.5cm height. The maximum speed of the robot achieved was 0.92 m/s on flat terrain, while the speed over the rough and uneven terrain was 0.76 m/s. The proposed amphibious system requires further investigation for its realization in real-life applications.