Steady-state dynamic analysis of a nonlinear fluidic soft actuator

The internal channel networks embedded within a soft structure can be a fruitful mechanism to create and activate actuators in the research fields of soft robotics. The deformation of the supporting elastic structure from the pressurized viscous fluid into the channels needs an accurate investigation. In this paper, accurate modeling and dynamic analysis of this nonlinear soft actuator is our goal. In this modeling, the soft actuator is considered the Euler-Bernoulli beam with large deflection and nonlinear strain. After implementing Hamilton's principle, the assumed mode method is used to achieve the mathematical model in terms of the multi-mode system that is more similar to the flexible nature of the actuation system. Steady-state dynamics is investigated by a combination of the complex averaging method with arc-length continuation. The accuracy of the proposed modeling is validated by comparing simulation results to those obtained with a nonlinear finite element method and numerical method. It shows that only one-third of the degree-of-freedoms used for the finite element method are sufficient to obtain equivalent converged solutions with the proposed model. The effect of nonlinear strain and multi-mode consideration in the analysis of the proposed modeling is investigated. It is advantageous to analyze the system performance by looking into the geometrical parameters and fluid properties.