In recent years, interest in in-pipe robot research has been steadily increasing. This phenomenon reflects the necessity and urgency of pipe inspection and rehabilitation as several pipe networks have become outdated around the globe. In-pipe robots can be divided into several groups in accordance with their locomotion principles, each with its own advantages and best suited application scope. Research on the screw drive in-pipe robot (SDIR) has had a rising trend due to the robot's simple

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... ng mechanism design and numerous advantages. This study compares and analyzes the characteristics of various SDIRs from the aspects of mechanism design, driving principle, and motion and mechanical behaviors. Each SDIR has its own advantages and disadvantages depending on its design requirements and intended applications. A number of prototypes have been fabricated to verify their functionality and efficiency in inspection tasks. This study can provide an up-to-date reference for researchers to conduct further analysis on SDIRs.