Design and Motion Analysis of a Soft Modular Robot for Diverse Environments

This article introduces the design and development of a modular soft robot capable of performing multiple movement modes. The core unit module features a four-chamber soft structure, separated by a cross-shaped thin plate. By selectively applying pneumatic pressure to different chambers and changing connector configurations, the robot achieves diverse modular configurations and movement modes, enabling it to adapt to various environments. To address the challenges posed by the material's nonlinear behavior and its infinite degrees of freedom, a three-dimensional spatial mathematical modeling approach is proposed. This method, grounded in classical plate theory and the chained composite model, establishes a static model for the soft robot's spatial bending motion with constant curvature. In addition, a single-controller framework based on a central pattern generator is developed to facilitate the generation of multiple movement gaits. By tuning parameters such as oscillator phase, frequency, load factor, and amplitude, the controller can generate a wide range of movement patterns. To validate the proposed theoretical and experimental models, we developed a pneumatic control platform that demonstrated the robot's multimodal locomotion capabilities through systematic testing in terrains with varying complexity.