Robust vibration isolation by frequency-shaped sliding surface control with floor velocity/acceleration measurement

This paper studies control of 1-DOF Active Vibration Isolation System (AVIS) using Frequency-Shaped Sliding Surface Control (FSSSC) approach based on the measurement schemes of the relative displacement and the floor absolute velocity/acceleration. Seismic velocity/acceleration sensors usually have large dimensions and mass which sometimes cause difficulties to fix them to the payload. The FSSSC approach has been recently applied to AVIS control and generalized as a two-step AVIS control design method. It is simple and has validated robust performance. Assuming linear regulation, both sliding surface design and the robustness of the realized performance are studied. The realized transmissibility is limited by the displacement sensor noise at high frequencies. The FSSSC designs of an example 1-DOF plant with the measurement schemes of the relative displacement and the floor absolute velocity/acceleration are provided. Theoretical calculations show that the robust low-frequency vibration isolation can be achieved but the performance robustness is limited at high frequencies due to the displacement sensor performance.