Disturbance Observer‐Based Fixed‐Time Super‐Twisting Sliding Mode Control for Vibration Isolation Platforms in Lithography Machines

ABSTRACT To improve the capability of the 6‐DOF vibration isolation platform for lithography machines to suppress both ground vibration and internal direct disturbances, this article proposes a fixed‐time super‐twisting sliding mode control strategy based on a disturbance observer (FTSMC‐DOB). This article applies the disturbance observer (DOB)‐based super‐twisting sliding mode control (SMC) algorithm to the lithography machine vibration isolation platform, which effectively overcomes the system's nonlinear and strongly coupled characteristics, significantly enhances the disturbance rejection capability, and provides a new approach for precision control in this field. Aiming at the shortcoming of traditional sliding mode algorithms whose convergence time depends on the initial state, a fixed‐time super‐twisting convergence control law is designed, achieving fast and predictable convergence performance, and the super‐twisting control technique greatly mitigates the inherent chattering problem. Within the improved algorithm framework, a fixed‐time disturbance observer (DOB) is integrated to achieve high‐precision real‐time compensation for disturbances, thereby enhancing the system's robustness. A comparative co‐simulation in ADAMS and Simulink under two typical working conditions—ground vibration isolation and direct disturbance suppression—demonstrates that the proposed method significantly improves vibration isolation accuracy, exhibits better stability and recovery capability under disturbances, delivers superior performance across the full frequency range, and greatly enhances the ultra‐low frequency isolation effectiveness, verifying its effectiveness and superiority in precision vibration isolation applications for lithography.