Because of size and complexity concerns, implementing feedback control for ionic polymer-metal composite
(IPMC) actuators is often difficult or costly in many of their envisioned biomedical and robotic applications.
It is thus of interest to develop open-loop control strategies for these actuators. Such strategies, however, are
susceptible to change of IPMC dynamics under varying environmental conditions, a predominant example being
the temperature. In this paper we present a novel approach to open-loop control of IPMC actuators in the
presence of ambient temperature changes. First, a method is proposed for modeling the temperature-dependent
actuation dynamics. The empirical frequency response of an IPMC actuator, submerged in a water bath with
controlled temperature, is obtained for a set of temperatures. For each temperature, a transfer function of a
given structure is found to fit the measured data. A temperature-dependent transfer function model is then
derived by curve-fitting each zero or pole as a simple polynomial function of the temperature. Open-loop control
is then realized by inverting the model at a given temperature based on the auxiliary temperature measurement.
However, the obtained model for IPMC actuators is of non-minimum phase and cannot be inverted directly. A
stable but non-causal algorithm is adopted to implement the inversion. Furthermore, a finite-preview algorithm
is proposed to enable near real-time tracking of desired outputs. Experimental results show that the proposed
approach is effective in improving the tracking performance of IPMC actuators under varying temperatures.