State–dependent system identification for control of a hydraulically–actuated nuclear decommissioning robot

Abstract

This article considers the identification of state–dependent parameter (SDP) models for the hydraulically actuated dual–manipulators of a mobile robot used for nuclear decommissioning tasks. A unified framework for calibration, data collection and system identification is developed, and utilized to investigate potential state–dependencies. The latter are associated with nonlinear system dynamics and can cause irregular joint movements when the device is controlled using linear control algorithms. The analysis suggests that a univariate SDP model is suitable for control design. The model has a state–dependent gain, characterized directly from experimental data using a numerically optimized polynomial function of the delayed input variable. In order to demonstrate the practical utility of the SDP model, closed–loop results using a novel non–minimal regulator for joint control are briefly considered.