This paper presents an approach to designing the input signal for an identification experiment, in which the process model estimate is to be used to formulate and sol e for a robust (in a worst case sense) optimal controller. The input signal is designed to contain the information that is relevant for the end use of the model, that is for control purposes. The proposed approach uses sensitivity analysis to determine the input signal frequencies that are important with respect to a certain measure of achievable controller performance in conjunction with a frequency sampling filter model of the process. Based on the sensitivity analysis, an iterative experimental design methodology is suggested. (C) 2005 Elsevier Ltd. All rights reserved.