Design of a triphibious robot with positive buoyancy for stable water-air cross-domain transition

This article introduces the design, analysis and experiment of an aquatic-ground-aerial triphibious robot capable of stable transition across water, land, and air environments, which is named BaiLong. Based on a multi-dimensional performance evaluation and comparison system, BaiLong is designed based on a coaxial dual-layer structure, utilizing four coaxial rotors and propeller thruster as aerial and underwater actuators, and a single-joint multifunctional undercarriage equipped with active wheels for ground motion. The coaxial dual-layer structure combined with positive buoyancy characteristics enable stable water-air cross-domain transition. The mathematical models of BaiLong have been established, and the influence of buoyancy characteristics on BaiLong’s mobility was investigated by the conservative potential energy model and buoyancy model. The simulations and experiments demonstrate the effectiveness of these designs and theories, and confirm the robot’s operational capabilities in different environments and its ability of stable water-air cross-domain transition.