Predicting force output of trilayer polymer actuators

This study aims at (i) deriving a mathematical model to predict the force induced at the tip of a trilayer bending type polypyrrole (PPy)-based actuator under input voltages and (ii) experimentally verifying the model. As opposed to the previous versions of these actuators, the actuator operates in air. The model has been extended to estimate the force produced by a robotic finger made up of the PPy actuator and a carbon fibre rigid link. All theoretical and experimental results presented show that the force model is accurate enough to predict the force at the tip of two actuators with the dimensions of (10 mm x 1 mm x 0.17 mm), and (5 mm x 1 mm. x 0.17 mm), and the robotic finger with the dimensions of ((5 + 5) mm x 1 mm x 0.17mm) under a wide range of input voltages. The response of the actuator and the finger under step input voltages is also evaluated and found that the actuator does not have any delay time, but has a large time constant. Two of the fingers are assembled to form a robotic gripping system, whose payload handling and positioning ability has been experimentally evaluated. The gripper can lift payloads as much as 50 times its total mass under a 1.5 V. (c) 2006 Elsevier B.V. All rights reserved.