A two-loop linear control utilizing ΔΣ modulator

The traditional approach of controller implementation is based on multi-bit signal processing. The present paper proposes an alternate approach of controller implementation based on single-bit signal processing. This requires less interface channels between the controller and other parts of the system and thereby consumes significantly less hardware resources compared to traditional multi-bit processing. The effectiveness of the proposed single-bit or bit-stream controller is experimentally illustrated by designing two single-bit PID controllers for controlling the position of a D.C. Motor. The outer loop PID controller is designed to provide appropriate reference for the inner speed control loop, which is controlled by an inner loop PID controller. Various functional blocks are designed to implement Proportional, Integral and Derivative action in single-bit environment. Experimental results from a laboratory prototype illustrate that the single-bit based PID controllers effectively controls the position and consumes approximately 500 logic elements (LE) on an Altera Cyclone FPGA.