Robust Tubular Prescribed Performance Control for Euler–Lagrange Systems With Actuator Dynamics

ABSTRACT Transient performance is critical for guaranteeing operational safety of Euler–Lagrange (EL) systems, but conventional robust control and prescribed performance schemes often fail to strictly enforce transient constraints and typically neglect actuator dynamics. In this article, a robust tubular prescribed performance control (TPPC) method is proposed for EL systems subject to external disturbances, actuator dynamics, and input saturation. Asymmetric tubular performance boundaries are constructed from the step response of a canonical second‐order system, which allows classical time‐domain specifications such as overshoot and settling time to be encoded explicitly via the natural frequency and damping ratio. This design leverages the intrinsic second‐order structure of EL dynamics and links prescribed performance directly to physically meaningful parameters. Actuator dynamics are modeled as first‐order systems followed by amplitude saturation, and an auxiliary anti‐saturation mechanism is introduced to compensate for actuator limitations. Robustness against unknown disturbances is achieved by integrating an immersion and invariance (I&I)‐based observer into the TPPC framework. A rigorous Lyapunov analysis establishes closed‐loop stability and proves that the tracking error remains strictly within the prescribed tubular boundaries. Comparative simulations demonstrate that the proposed TPPC effectively suppresses overshoot and oscillations, preserves input feasibility, and maintains robust performance under actuator dynamics and external disturbances.