Analytical modeling of a segmented unimorph actuator using electrostrictive P(VDF-TrFE) copolymer

Abstract

An analytical model is developed for a segmented unimorph actuator consisting of electrostrictive P(VDF-TrFE) copolymer. The segmented actuator consists of individually controlled segments of the active polymer so that varying curvature along the length can be achieved. The analytical model incorporates large deflections and can be used to predict the free deflection and blocked force along the length of the actuator. The target application is active instruments for minimally invasive surgery (MIS), where steerable tool tips are needed to increase dexterity and provide nonlinear access. Results are presented to illustrate predicted free deflection and blocked force for various electric fields. An optimization procedure is also employed to design an actuator for maximum tip deflection, blocked force and out-of-plane stiffness. The predicted deflection performance of the optimized design is shown to be suitable for application to minimally invasive surgery.

An electromechanical model for characterizing sensing and actuating performance of unimorphs based on “plain” dielectric polymers

“…It can be seen that the performance characteristics of high performing dielectric polymer nanocomposite PU-3.5 wt% o-CuPc are comparable to that of best performing electrostrictive and piezoelectric materials. segments can be controlled independently, as studied in [15][16][17], are also important but shall be considered in subsequent works. Unimorphs are slender structures with length to thickness ratios of over 100.…”

Review of robotic fixtures for minimally invasive surgery

“…The snake is suitable for use as an endoscope. Pennsylvania State University has also designed another EPAM snake-like endoscope for low invasive tasks (17) . Three layers form the segmented actuator; a central passive substrate sandwiched by two layers of EPAM ( Fig.…”

Design, Fabrication, and Modeling of an Electric–Magnetic Self-Folding Sheet

“…Analytical models have been developed to account for the interaction of active materials with specific beam geometries. They have been utilized to develop a design concept for a variable curvature electrostrictive polymer beam [25] as well as a model of a multifield terpolymer-MAE bimorph [26]. While very few assumptions are made regarding the crease and active materials models, analytical models are limited to geometries for which analytical kinematic solutions exist.…”