The dynamics of hydraulic systems are highly nonlinear. Aside from the nonlinear nature of hydraulic dynamics, hydraulic systems also have large extent of model uncertainties, either due to parametric uncertainties or uncertain nonlinearities. These nasty characteristics make the precision motion control of hydraulic systems rather difficult. As a stepping stone toward the systematic design of high performance control algorithms for hydraulic systems, a nonlinear model based adaptive robust control approach is presented and carefully examined through both rigorous theoretical analysis and experimental verifications. Specifically, nonlinear physical model based analysis and design is used to address the inherent nonlinearities of hydraulic dynamics. Adaptive robust control (ARC) is applied to deal with various model uncertainties effectively. This book starts from the precision motion control of one Degree-of-freedom (DOF) hydraulic servo system. The coordinated motion control of multi-DOF electro-hydraulic robotic arm is then studied. Extensive experimental results are presented to validate the effectiveness of proposed control algorithms