A Review of Soft Crawling Robots with Different Driving Methods

Background: Traditional rigid robots are difficult to adapt to complex unstructured environments due to their limited degree of freedom and lack of flexibility. Therefore, soft crawling robots are concerned widely by their powerful deformation ability, infinite number of degrees of freedom, and effective interaction with humans. Objective: This paper aims to report the recent progress of soft crawling robots and provide a reference for readers in this field. Methods: By reading and summarizing the patents and papers related to soft crawling robots in recent years, they are divided into three categories according to different driving methods. The structure, motion mechanism, characteristics, and applications of each class of robots are compared and analyzed. Results: The advantages and disadvantages of each driving method are analyzed, and the key issues in soft crawling robots are pointed out. Based on this, the future development direction of this research field is predicted. Conclusion: The study shows that according to the driving method, soft crawling robots are classified as pressure driven, motor-wire driven, and soft active material driven. In addition, the characteristics of each drive are summarized. In the future, soft crawling robots will have more potential applications in biomedicine, outdoor survey, rescue search, and inspection and maintenance of equipment.