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Robust Feedback Control and Updating for large scale distributed systems

Project members:  prof. M. Verhaegen, Post Doctoral Position (3 years) and 2 PhD Positions (Vacancies)
Keywords:  Control of high-resolution imaging, Distributed estimation and control, Robust control, Spatial-temporal large-scale systems, Optics and imaging
Sponsored by:  European Research Council
For the restoration of images knowledge of the spatial-temporal dynamics of the aberrations is crucial. In the new context of the iCON Advanced Grant Research Project sponsored by the European Research Council, image restoration will be addressed within the context of real-time feedback control, making use of actuators like deformable lenses or mirrors in addition to classically used image sensors. Using the mathematical model information and updating of the aberration dynamics as acquired via the new Subspace Identification methods, real-time Robust Feedback control methods will be developed in this project. The challenges for the new robust control methods for image restoration are twofold:

- The 2D spatial and temporal dynamics: The requirement of high resolution imaging generally leads to the use of a large number of actuators and sensors to attain the necessary spatial resolution. Considering these numbers in the order of 104 with a temporal data acquisition in the order of a few kHz, excludes the use of present centralized subspace identification methods. Instead a distributed methodology allowing execution on a multi-core GPU/GPU where each core has access to a small subset of sensors and actuators only. In addition for data reduction the algorithms will be integrated with compressive sensing.

- Both linear and Wiener nonlinear, time-varying dynamics: The used imaging sensor determines whether there is a linear or nonlinear relation with the aberrations. For example when using Shack-Hartmann sensors linear relationships can be assumed. However when making use of CCD readings the relationships becomes (spatially) non-linear. Combining this with linear temporal dynamics leads to either consider linear time-varying or Wiener time varying dynamics. The time varying nature needs to be considered since the aberrations dynamics vary in time and acquire falsification resp. updating of the current controller.

The new algorithmic developments will be demonstrated in 2 state of the art laboratory demonstrators that will be built up in the Smart Optics Laboratory of Prof. Michel Verhaegen. The first demonstrator is a breadboard emulating the large dimensionality of the Adaptive Optics control problem in the European Extreme Large Telescope and the second is about multi-photon microscopy. iCON is sponsored by the Advanced Grant Program of the European Research Council. This funding will bring a core team of 6 temporary researchers together with world wide leading experts for a period of 4 years starting early 2015.


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