Investigation of Lateral Compression Effects in Fiber Reinforced Soft Pneumatic Actuators

Soft material robotic systems are a comparably new field of research. In contrast to classical robots, soft material robotic systems (SMRS) are characterized by their low stiffness. This gives them a high degree of flexibility and compliance. The associated inherent safety makes them a promising technology for applications which require human-machine interaction or a high level of adaptability. Still there exists no generic methodology for modeling and control of these systems. One approach is to use the sophisticated Finite Element Method (FEM) or classical beam models. This paper deals with the modeling of fiber reinforced soft pneumatic actuators (SPAs). We present an approach to convert the input pressure to equivalent forces and to implement them into a Cosserat rod model. FE analyses provide a high level of detail, thus, they indicate a strong influence of compression effects on the chamber wall. We consider the forces resulting from this lateral compression when setting up a Cosserat rod model. Identification of the rod's parameters and subsequent validation against FE simulations show good accordance up to a certain pressure limit. The influence of geometrical features on the compression effect is demonstrated and quantified by a compression factor α.