Colloquia

Samenvatting

Modern semiconductor inspection systems demand extreme precision due to their nanometre-scale features. Even minor environmental vibrations, particularly ground-borne ones, can degrade performance. As these disturbances are difficult to eliminate at the source, they are mitigated using passive, active, or hybrid vibration isolation platforms. Designing such systems requires careful trade-offs in performance across the operating frequency range.

Previous research at the University of Twente explored active vibration isolation, but this study shifts focus toward real-world implementation. It centres on developing an isolation platform for a precision motion system used in the semiconductor industry, aimed at minimising position jitter, high-frequency oscillations during standstill. This involves dynamic characterisation of the system, modelling key disturbances such as floor vibrations, sensor noise, and actuator dynamics, and synthesising robust controllers via combined H2/Hinf optimisation.

A key element of the approach is Dynamic Error Budgeting (DEB), which traces disturbance propagation through the system and quantifies its impact on performance. DEB informs system modelling, disturbance shaping, and the design of weighting filters used in robust control synthesis.

Building on this foundation, the second part of the study evaluates and improves system performance. Experimental data is used to extract modal parameters and refine the model. Transmissibility functions support multi-degree-of-freedom (MDOF) analysis. A series of structured case studies explores variations in control strategies and physical design choices. These include tuning controller bandwidth, modifying feedback architectures, and adjusting dynamic parameters to improve vibration isolation.

This methodology significantly reduces transmissibility to external disturbances, thereby improving suppression of vibration-induced jitter. By integrating DEB with robust H2/Hinf-control co-design, the framework enhances disturbance rejection and noise shaping while maintaining system stability and robustness. This comes at the cost of higher high-frequency control effort, a trade-off inherent in active systems.