Mechatronics

Chapter 2

Modeling and Control of Ionic Polymer-Metal Composite Actuators for Mechatronics Applications ¹

This chapter presents the full design process through to the implementation of two innovative mechatronic devices: a stepper motor and a robotic rotary joint both with integrated soft IPMC actuators. Firstly, electromechanical modeling of the IPMC actuation response is presented. This model is then used as a tool for the mechanical design of the devices. Novel implementation of control systems to adaptively handle the highly nonlinear and time-varying response of the IPMCs and achieve successful device performance is undertaken. Experimental results are presented to validate the designs for the systems. This work demonstrates the capabilities of IPMCs and the benefits of implementing them as valid alternatives to traditional actuators.

2.1. Introduction

Ionic polymer-metal composites (IPMCs) are a novel type of smart material transducer. They are a class of electroactive polymer (EAP), acting as an actuator under the influence of an electric field and conversely producing an electric potential when mechanically deformed. Typically IPMCs have been operated in a cantilever configuration (see Figure 2.1) where a voltage is either applied or measured at the base through a set of clamped electrodes. A beam type actuation greater than 90° can be achieved with small applied voltages, typically less than 5 V. Sensing voltage is usually orders of magnitude lower than the voltage ...