An inter - disciplinary approach to investigating the use of virtual reality environments for people

A device for controlling the grinding of a piezo-electric element is designed to convert the frequency of an electric signal produced with grinding of a piezo-electric element into a lower frequency, using frequency converters and a local oscillator and then to select, by means of filters, a frequency generated from the frequency converters at the time when a desired grinding of a piezo-electric element has been obtained so as to bring the grinding operation to a stop in response to the selected signal.