Question

Why don't stepper motors need encoders? Good accuracy of stepper motor without encoder?

Answer 1

A stepper motor is a motor capable of position control without feedback, and its movement is controlled by a current signal. Therefore, compared to conventional servo motors, stepper motors do not require an encoder to feedback position information.

The rotor of a stepper motor has a fixed number of step angles, and the position of each step is fixed, so its position can be determined by the number of pulses sent by the controller at each step. The controller of the stepper motor can accurately control the step angle and the number of steps, thus achieving precise position control.

In addition, the controller of the stepper motor can monitor the status of the motor in real time and adjust the output pulse to ensure that the motor stops at the correct position, thus avoiding the need for encoder feedback on position.

In general, stepper motors do not need encoders mainly because they have fixed step angles and programmable controllers that enable precise position control and condition monitoring. This makes stepper motors an efficient, reliable and cost-effective solution in many applications.

Answer 2

A stepper motor is essentially a stupid open-loop control thing. Rely on the internal cogging structure of the motor to position, as long as it does not need to rotate fast and does not need to be strong, it can be well positioned.

As for the stepper motor with servo now, it is indeed better, but it feels overdesigned. 

I don't know if it is better to use a servo motor plus a rotary encoder, whether it will be more expensive. From the outside alone, if it is possible to use only the combination of motor and rotary encoder without adding a grating ruler, the complexity of the mechanism is no different from that of a stepper motor.

Answer 3

Stepping can realize the positioning control of the motor rotor through the control of the winding current, so in most stepper motor applications, the position control of the motor can be achieved without an encoder, just because of the open-loop control, the positioning accuracy will be worse in the absence of an encoder, generally the step angle of the stepper motor is positioned as positioning accuracy.

Answer 4

Why don't stepper motors need encoders?

Stepper motors do not need an encoder because their motion is based on quantitative pulse control rather than on continuous rotation or position feedback. 

Once the motor receives a pulse signal, it moves precisely to the next specified position. Therefore, if the current position of the stepper motor needs to be determined, the position of the motor can be deduced by counting the pulse signal sent before.

Answer 5

Due to the unique structure of stepper motors, no encoder is required.

Answer 6

The movement of a stepper motor is controlled by the current pulse sent by the motor controller based on a certain number of step angles. Because the motion of stepper motors is divided into a corresponding number of step angles, they can accurately control the step angle of motor rotation to achieve displacement and speed control; The encoder is used to feedback the position and speed of the actual movement of the motor to improve the control accuracy; Therefore, stepper motors do not require encoders to feedback position and speed information.