Mechanical Modeling and Optimal Model-based Design of a Soft Pneumatic Actuator

Soft pneumatic actuators are widely used for soft grippers, which are known for their compliance as compared with traditional grippers. The generated force/torque of soft pneumatic actuators directly determines the grasping force. This paper introduces a computationally efficient soft pneumatic actuator (SPA) design methodology. The complex structure of the pneumatic actuator is approximated by a cantilever beam. The relationship between input pressure and output torque is derived by standard mechanical analysis. The design problem is formulated as a model-based optimization problem by treating the input-output mathematical model as the objective function. By solving the optimization problem, the optimal design parameters are obtained. Finite element analysis is applied to preliminarily verify the design parameters without the time-consuming fabrication of many actuators. Three soft actuators with different design parameter sets were fabricated to validate the optimal parameters. This work shows the utility of surprisingly simple calculations and assumptions for rapid parametric design studies.