On the numerical speed control of electrical drive systems using stepping motors

The paper focuses on the speed control of stepping motors in a closed-loop configuration. An incremental optical encoder is used as the position transducer, allowing the achievement of a minor loop. The numerical control algorithm is implemented using an IBM PC together with a specialized interface for stepper motors. The solution was obtained in two steps: the first was a nonlinear control law and the second was the improvement of the first one by using a PI part.