Abstract: General, high-precision theoretical modeling method is not well developed in the field of soft robotics, which holds back motion control and practical application of soft robots. The concept of modularization brings novel structure, novel locomotion patterns as well as novel control method for soft robots. This paper presents the concept of hierarchical control method for modular soft robot system and a H-configuration pneumatic modular soft robot is designed as the control object. The H-configuration modular soft robot is composed of two basic motion units that take worm-like locomotion principle. The locomotion principle of the basic motion unit is analyzed and the actuation sequence is optimized by evolution strategy in VOXCAD simulation software. The differential drive method is applied to the H-configuration modular soft robot with multi motion modes and vision sensor is used to control the motion mode of the robot. The H-configuration modular soft robot and the basic motion unit are assembled by a cubic soft module made of silicone rubber. Also, connection mechanism is designed to ensure that the soft modules can be assembled in any direction and posture. Experiments are conducted to verify the effect of the hierarchical control method of the modular soft robots.

Key words: Soft robot, Modular robot, Locomotion pattern optimization, VOXCAD simulation software, Vision feedback control