In this chapter, we explore state-feedback and output-feedback control strategies for a class of Euler–Lagrange systems under input saturation, actuator faults, and measurement constraint. In practical applications, a large magnitude of control input is often required for achieving fast tracking convergence [9]. However, due to the limitations of physical mechanisms, the control input is inevitably constrained within an effective region. Due to the complex saturation nonlinearities, how to cope with these effects has become a challenging research topic. Moreover, most works are followed by the assumption that all the system states are available. The unmeasurable systems states make the traditional state feedback control in applicable. To address the abovementioned problems, we develop a series of nonlinear control designs for Euler–Lagrange systems and the main contributions are summarized as follows: To compensate for the saturation nonlinearity, a virtual auxiliary system is constructed, and a backstepping-based constrained control is proposed. A novel saturation constraint mechanism for the control input derivative is designed for alleviating the chattering phenomenon. Inspired by the second-order sliding mode control, a novel second-order dynamic surface control is developed, which not only ensures the finite-time convergence of the closed-loop system but also satisfies the input saturation constraints. Finally, we further consider actuator faults and unmeasurable states. A finite-time output feedback control is designed where fuzzy logic systems are utilized to estimate the unmeasurable states. The effectiveness of the proposed control designs is verified by numerical simulations.