Pertubation Compensator based Robust Tracking Control and State Estimation of Mechanical Systems This monograph investigates a practical way to achieve robust motion control and state estimation (Kalman filtering) of mechanical systems which is a promising approach in terms of the perturbation compensator. The book presents novel approaches for design and analysis of perturbation observers as well as an extension to robust motion control and robust state estimation. The book is written in a self contained manner including experimental results in each chapter clearly validating the developed theories. TOC:Introduction. Robust Tracking Control with Hierarchical Perturbation Compensation. Robust Performance of the Multiloop Perturbation Compensator. Discrete Time Design and Analysis of Perturbation Observer. Combined Observer Design for Robust State Estimation and Kalman filtering. Control of Coarse Fine Dual Stage Positioning System. Concluding Remarks