TU Wien's open-source FPGA framework enables real-time LQG control for nanomechanics

Vojtěch Mlynář and colleagues from TU Wien and the AIT Austrian Institute of Technology have introduced an open-source framework that brings advanced real-time control to nanomechanical systems using the low-cost Red Pitaya STEMlab FPGA board. The system implements a Linear Quadratic Gaussian (LQG) controller—combining a discrete-time Kalman filter for state estimation with a Linear Quadratic Regulator (LQR)—capable of handling up to three coupled oscillatory degrees of freedom. Complementing the controller, the framework includes a hardware-in-the-loop (HIL) simulator that models a configurable second-order stochastic plant with nonlinear input/output mappings, enabling realistic closed-loop testing under fixed-point and real-time constraints.

A MATLAB-based workflow automates model configuration, controller synthesis, numerical scaling, and FPGA deployment, lowering the barrier for experimentalists without specialized hardware expertise. As a end-to-end demonstration, the team stabilized a levitated nanoparticle in a two-dimensional double-well potential, showcasing the complete pipeline from simulation to real-time feedback. This work opens the door for affordable, reproducible control experiments in levitated optomechanics, MEMS/NEMS, and quantum sensing—fields typically reliant on expensive, custom hardware.