Experiment to evaluate the feasibility of the Smart Disc concept

Performance of contemporary high-tech equipment is more and more determined by accuracy. Positional deviations due to high frequent vibrations in the floor can be suppressed by mounting the equipment on a frame that acts as a low-pass filter, but low frequent deviations and deviations due to motions inside the machine can only be reduced by increasing the machine frame stiffness. When only passive elements are used during design, large stiffness can only be attained with rigid bodies, which often exhibit bad dynamic behaviour. In case a machine should be both accurate and fast, a design with active elements should be considered. The Smart Disc is an example of such an active element. It integrates a piezoelectric sensor, a piezoelectric actuator and control electronics, such that it expands when it experiences a compressing force, and vice versa. Insertion of Smart Discs at discrete locations in a machine might compensate for the lack of frame stiffness. To evaluate the feasibility of the Smart Disc concept an experimental set-up has been designed. Though only one prototype Smart Disc is utilised, the set-up resembles a large class of machines suffering from deviations caused by the non-infinite frame stiffness and non-filtered vibrations in the floor. Experiments with this set-up show a reduction of the positional error of interest in the order of 20 dB in a frequency range of 0.1 to 10 Hz.