Design and modeling of an active steerable end-effector

A model has been developed in MATLAB to design a new active, steerable end-effector. The end-effector design consists of a number of bimorph actuator sections in series with each active layer being individually controlled. Each section may behave as either a bimorph or a unimorph actuator, where in the case of unimorph one of the active layers is passive. By varying the strength and direction of the electric field across each section, a prescribed overall shape can be achieved to allow the user to steer the device. The focus of this paper is on the model of the end-effector using electroactive polymer (EAP) materials. In the EAP model, experimental data for the electrostrictive P(VDF-TrFE) copolymer is used to model the nonlinear relationship between the electric field and the induced strain. Due to the large deflections achievable with the EAP, a pseudo rigid-body model for large deflections beams is also used. The behaviour of piezoelectric ceramic is compared to that of electro-active polymer (EAP). The target application for this steerable device is a small-scale smart surgical instrument for minimally invasive surgery.