Hierarchical disturbance/uncertainty estimation and attenuation for integrated modelling and motion control: Overview and perspectives

Advanced motion control with higher precision and faster dynamic response is emerging as an enabling technique for higher performance mechatronic systems. In this paper, a systematic hierarchical disturbance/uncertainty estimation and attenuation (HDUEA) motion control framework is presented for cutting-edge and higher-precision mechatronic systems under various working conditions to counteract the most deleterious factors, including a wide operating range, nonlinear characteristics, unmatched/multiple disturbances, and uncertainties. This article will review the state-of-the-art of basic components for modelling, analysis, and motion control of mechatronic systems. Built on this, the promising framework of HDUEA consisting of three layers is elaborated. The first layer is on feature analysis and classification of nonlinearities, disturbances and uncertainties. The second layer focuses on modelling and identification of modelable nonlinearities, observation and reconstruction of estimatable disturbance/uncertainties. In the last layer, a composite hierarchical control strategy includes nonlinearity cancellation-based nonlinear feedback, feedforward disturbance compensation, and robust feedback suppression of unmodelable/unobservable nonlinearities, disturbances and uncertainties. Based on this HDUEA framework, the challenges faced by motion control systems are resolved comprehensively. Finally, the article ends with a discussion of open problems and perspectives in this research area.