Nanoradian digital stabilization of a suspended table for scientific experiments

Digital control design of a suspended table for scientific experiments is presented. The problem was suggested by an experiment to measure the universal gravitational constant G. It requires two residual rotations of the table with respect to the horizontal plane to be kept below 1 nrad. The problem was tackled by assuming a 2D inclinometer 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 version of the digital control unit show that the requirements might be met.