Development of a waterproof servo unit for amphibious robots

Amphibious robots based on hybrid locomotion mechanisms have better environmental adaptability than conventional wheeled or tracked mobile robots, and therefore have great potentials to be valuable robotic assistant for aiding search and rescue operations after natural or industrial catastrophes, such as tsunami, floods, or mining disasters. However, their locomotion mechanisms and sensory circuitry are complex and vulnerable to water and dust contaminants, which prevents them from being practically used at disaster sites. In this paper, implementation of a waterproof servo unit is proposed as a simple and economic protection measure based on decentralized sealing strategy for two of the most vital components in amphibious robots, namely the servo motor and the absolute encoder. Crucial design considerations relating to waterproof function of the motor and accuracy of the encoder are discussed. Prototypes of the motor shield and the waterproof encoder are fabricated. Finally, the proposed idea and designs are verified by experiments.