A Proposal of a PID Feedback Controller with High Precision and Wide Dynamic Range : It s Application to Seismometers

A rnethod of digital feedback control was established rnore than 20 years ago. It s applications have been developed in fuzzy and adaptive control rnethod used in washing rnachines. To date ， technologies of cornputers with high speed and ADC (Analog Di gital Converter) with wide dynarnic range have been advanced. Therefore ， the digital feedback control rnethod has enough potential to be ernployed to a servo-type seisrnorneter instead of its analog feedback circuit. However ， to use the digital feedback control ， the problerns to be overcorne still rernain. Those are the dynarnic range and the data acquisition speed of ADC/DAC (Di gital Analog Converter). This paper proposes an idea to obtain ADC/DAC with wide dynarnic range and high-speed data acquisition. In a case of DAC ， we use two devices for one data output. One is used to convert upper-half bits of the data and the other is for lower-half bits. ADC also has the sarne situation. By the above-rnentioned rnethod using the two devices with srnaller bit-width ， the higher data-acquisition speed and the data with a wider dynarnic range will be obtained. Now ， we will try to develop a PID digital feedback control circuit using the rnethod. The rnethod is patent pending.