Performance quantification of conducting polymer actuators for real applications: a microgripping system

In this paper, we report on modeling, characterization, and performance quantification of a conducting polymer actuator, driving a rigid link to form each finger of a two-finger gripping system, which is what we call a microgripping system. The actuator, which consists of five layers of three different materials, operates in a nonaquatic medium, i.e., air, as opposed to its predecessors. After the bending displacement and force outputs of a single finger are modeled and characterized including the effect of the magnitude and frequency of input voltages, the nonlinear behavior of the finger including hysteresis and creep effects is experimentally quantified, and then a viscoelastic model is employed to predict the creep behavior. The experimental and theoretical results presented demonstrate that while the hysteresis is negligibly small, the creep is significant enough so as not to be ignored. The response of the actuator and the finger under step input voltages is evaluated, and found that the actuator does not have any time delay, but only a large time constant. Two of the fingers are assembled to form a microgripping system, whose payload handling and positioning ability has been experimentally evaluated. It can lift up to 50 times its weight under 1.5 V. The payload handled was a spherical object covered with industrial type tissue paper. The friction coefficient between the object and the carbon fiber rigid link has been determined experimentally and used to estimate the contact force. All the theoretical and experimental performance quantification results presented demonstrate that conducting polymer actuators can be employed to make functional microsized robotic devices.