The field of modern control was established in the 1960s by controls theorists; its techniques provide robust, optimal control and are inherently capable of stabilising multiple input / multiple output (MIMO) systems.
MIMO systems are ubiquitous in interferometric gravitational wave detectors (GEO600 makes use of over 250 partly-nested control loops for operation), yet so far this valuable resource has not been used. Using techniques such as Kalman filtering the power of modern control can be exploited to more robustly stabilise highly complex systems, such as certain subsystems of interferometric gravitational wave detectors.
Our group has been participating in an effort to use modern controls for the local control of triple-pendulum-suspended test masses for the AEI 10 m prototype. This work is being carried out in collaboration with members of the AEI prototype group and Prof. Kenneth Strain (U Glasgow, UK). We are currently in the process of constructing a model triple-pendulum system that will resemble the actual suspensions to be employed in the AEI 10 m prototype as closely as possible.