Answer: C. The function is to convert the electrical pulse into angular displacement.
Analysis: Stepper motor is a digital motor, and its internal structure is composed of a ferromagnetic rotor and a control winding. When the control winding receives a pulse signal, it generates a rotating magnetic field that causes the rotor to rotate at an angle.
Therefore, the function of the stepper motor is to convert the electrical pulse signal into angular displacement, that is, every time a pulse signal is received, the rotor rotates a certain angle, so as to achieve accurate angular displacement control.
The advantages of stepper motors are simple control, high precision, fast response, etc., so they are widely used in automation control, computer peripherals, robots and other fields. However, stepper motors are sensitive to interference and need to take corresponding anti-interference measures. In addition, stepper motors do not have load capacity and rely on drives for energy.
Therefore, option C is correct and options A and B are wrong. At the same time, the "error will not accumulate" in option D is also wrong, because the stepper motor may accumulate errors during operation, especially in high-precision and high-speed applications, and corresponding error compensation measures need to be taken to ensure accuracy and stability.