On the general dynamic modeling method for soft bending actuators with multiple fluidic chambers

The complex structure, infinite degrees of freedom, and non-linearity of soft actuators make dynamic modeling one of the most challenging tasks in the field of soft robotics. Furthermore, few studies on general dynamic modeling methods for soft actuators with varying structures has been conducted to date. This paper introduces a novel modeling approach for symmetrically chambered soft bending actuators, offering a simple, low-cost, and highly practical solution. First, the actuator with a rectangular cross-section is taken as the standard type to build an analytical prototype model. Next, a structural equivalence method is proposed to convert non-standard actuators into standard types, making them suitable for the prototype model. Finally, the dynamic model of the non-standard actuator is developed by combining the prototype model with error compensations. Four soft actuators with different cross-sections were fabricated to verify the modeling approach's feasibility. The results proved that it is simple to obtain the dynamic models of various soft actuators using the proposed method. Model-based angle tracking experiments for these four actuators were conducted to confirm the effectiveness and usefulness of the dynamic models developed with the proposed modeling method.