Nanoradian digital stabilization of a suspended table for scientific experiments

Digital control design of a suspended table for fine scientific experiments is presented. The problem was suggested by an experiment to measure the universal gravitation constant $G$, requiring two residual rotations of the table with respect to the horizontal plane to be below 1 nrad. The problem was tackled by assuming a 2D clinometer and accelerometers as transducers. As actuators, linear electric moving-coil motors are necessary to avoid contact between the building and the table. The digital control was designed and tested using a fine numerical simulator of the plant and of environmental disturbances. The simulation tests of a first simplified version of the Digital Control Unit showed that the requirements may be met