Advances In Piezo Nanopositioning Controllers – Digital Vs. Analog

History of Digital Motion Controllers
Position control for magnetic motors has been almost exclusively digital for nearly three decades. In the mid-1980s, digital motion control chips began to be available, such as the pioneering HCTL-1000 chip from HP. These chips were easy for controls engineers to interface with the position feedback encoders of the era that provided simple, incremental quadrature signals suitable for digital processing. Also, for motors, the drive signal is a velocity or force command, so only low output resolution was necessary, regardless of axis travel. 10 bit analog or 8 bit PWM output resolutions were common, and these were very tractable for controller designers to employ in cost-effective designs. With the exception of analog tachometer feedback integrated as a supplementary loop for higher-performance systems of that era, magnetic motor control has been virtually all-digital ever since.