Which motor type offers fine multi-step positioning and is often used open-loop or with microstepping?

• A. Servo motors
• B. DC motors
• C. Stepper motors
• D. Induction motors

Answer: (C)

Fine multi-step positioning is a defining trait of stepper motors. They move in fixed angular increments, so you can place the rotor very precisely by issuing a specific number of steps. Because each step is a distinct position, they can be driven without feedback in many open-loop control setups, provided the load is predictable and the torque at each step is sufficient to prevent missed steps. When even higher resolution or smoother motion is needed, microstepping uses carefully shaped currents in the windings to interpolate between full steps, effectively creating intermediate positions and increasing positional accuracy without adding sensors. Other motor types don’t rely on discrete steps inherently: DC and induction motors run continuously and require feedback or specialized control for precise positioning, while servo systems provide precise closed-loop positioning but rely on feedback rather than natural stepping.