Trajectory Tracking Control of an Electro-Optical Stabilized Platform Using Frequency-Domain Precompensation and a Bandwidth-Separated Cascaded Extended State Observer

This paper proposes a composite control method integrating frequency-domain precompensation (FDP) with a bandwidth-separated cascaded extended state observer (BSCESO), hereafter termed FDP-BSCESO, for high-precision line-of-sight trajectory tracking of an electro-optical stabilized platform. First, the reference trajectory is reconstructed offline using the identified closed-loop frequency response. Within the effective closed-loop bandwidth, inverse magnitude and phase compensation is applied to reduce amplitude attenuation and phase lag without increasing the feedback bandwidth. Second, the BSCESO employs a low-bandwidth first-stage observer and a higher-bandwidth residual observer to hierarchically estimate and compensate disturbance components with different temporal characteristics. The boundedness of the observer errors and the input-to-state stability of the closed-loop tracking error dynamics are analyzed. Comparative simulations against PID, ADRC, and SMC under disturbance-free, band-limited random-disturbance, and multi-frequency deterministic disturbance conditions show improved tracking and disturbance-rejection performance. Across the tested external-disturbance cases, the root mean square tracking error is reduced by 38.83–65.11% relative to the best-performing benchmark in the corresponding cases.