A review of modular soft robots: Drive modes, motion modes, and connection modes

Modular soft robots demonstrate significant advantages such as reconfigurability, environmental adaptability, and motion flexibility by integrating the characteristics of modular design and flexible materials. In this paper, we systematically sort out the current research status of modular soft robots, and analyze their design features and application scenarios according to the three composition modes of assembled, reconfigurable, and self-reconfigurable. In terms of drive modes, the paper focuses on the principles, performance and limitations of fluid drive, shape memory alloy (SMA) drive, electromagnetic drive, and other technologies. At the motion modes aspect, the principles and realization methods of bionic for crawling, jumping, rolling, and other modes are elaborated in detail. In addition, the innovations and challenges of inter-module connection technologies are systematically summarized in terms of connection modes, revealing their key roles in robot functional diversity and reconfigurability. Finally, this paper looks forward to future research directions, including the development of high-performance smart materials, drive efficiency optimization, artificial intelligence fusion, and application expansion in medical and industrial fields.