High-speed digital controllers using an 8 bit microprocessor

Structures and algorithms for implementation of digital filters are described which enable high-performance controllers using 8 bit microprocessors to be designed. Using these techniques a typical controller for an electromechanical system incorporating two feedback signals, a phase advance compensator, a notch filter and a proportional-plus-integral term can operate at up to 750 Hz sampling frequency. The paper summarizes the development of the structure for the digital filters within the controller, describes the number format for the variables and coefficients, and outlines the software techniques employed to facilitate particular controller implementations.