Effective enhanced model for a large deformable soft pneumatic actuator

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Soft pneumatic actuators have been widely used for implementing sophisticated and dexterous movements, due to numerous fascinating features compared with their rigid counterparts. Relatively speaking, modeling and analysis of an entire soft pneumatic actuator considering contact interaction between two adjacent air chambers is extremely rare, which is exactly what we are particularly interested in. Therefore, in order to establish an accurate mechanical model and analyze the overall configuration and stress distribution for the soft pneumatic actuator with large deflection, we consider the contact interaction of soft materials rather than hard materials, to produce an effective enhanced model for soft contact of a large deformable pneumatic actuator. In this article, a multiple-point contact approach is developed to circumvent the mutual penetration problem between adjacent air chambers of the soft actuator that occurs with the single-point contact approach employed in linear elastic rigid materials. In contrast to the previous simplified rod-based model that did not focus on contact interaction which was adopted to clarify the entire deformation of the actuator, the present model not only elaborates nonlinear large deformation and overall configuration variations, but also accurately delineates stress distribution law inside the chamber structure and the stress concentration phenomenon. By means of a corresponding static experiment, a comparison of the simulation results with experimental data validates the effectiveness and accuracy of this model employing a multiple-point contact approach. Excellent simulation of the actual bending deformation of the soft actuator is obtained, while mutual penetration is successfully circumvented, whereas the model with single-point contact cannot achieve those goals. Finally, as compared with the rod-based model, the results obtained using the proposed model are more consistent with experimental data, and simulation precision is improved.