Pipeline robots: a comprehensive review of drive mechanisms, control strategies, and emerging challenges

Pipeline robots represent intelligent systems engineered for confined and complex pipeline environments. They feature compact and flexible architectures, diverse locomotion modalities, and a high degree of functional integration. These systems have been widely applied in industrial equipment inspection, energy infrastructure maintenance, and the management of urban underground utilities. This review systematically analyzes the technological characteristics and recent advancements in pipeline robotics, with a focus on drive mechanisms and motion control strategies. It presents the evolution and comparative analysis of three primary drive architectures: passive-driven, self-driven, and compound-driven, with representative applications, advantages, and limitations. In addition, an integrated research framework is proposed that encompasses energy efficiency management, drive systems, adaptive mechanisms, perception, navigation, and intelligent adaptive control to address critical challenges in environmental adaptability, energy efficiency, and autonomous task execution. Finally, the review outlines emerging trends and unresolved technical bottlenecks, providing theoretical insights and practical guidance to support ongoing innovation and real-world deployment of pipeline robotic systems.